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Bristol Fighter: planes we hope one day to fly


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#1 WW1EAF_Ming

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Posted 20 May 2010 - 19:15

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#2 Viper69

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Posted 20 May 2010 - 19:16

Wow! what a read!
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#3 J2_squid

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Posted 20 May 2010 - 20:06

This stuff is gold dust ming :D
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#4 Miggins

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Posted 20 May 2010 - 23:05

Thanks for getting these Ming.
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#5 Lormar

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Posted 20 May 2010 - 23:41

This is great, and invaluable, and not just to ROF. The Old Rhinebeck Aerodrome collects these sort of documents, and you just added to our collection! So thanks!
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#6 piecost

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Posted 12 November 2010 - 12:32

P1lot magazine June 2000

Bristol Fighter

The slashing rain had stopped. A largely leaden sky tramped slowly by, revealing golden linings full of temptations to fly. The 1917 Bristol Fighter was there and serviceable, the bodies eager to swing the prop, an empty airfield and nothing else to inter­fere. A perfect formula, excepting the pilot's lack of preparation.

The Brisfit stood proudly, distinctly British, rocking gently in the breeze. I saw it clearly, perhaps for the first time. A beautiful scimitar, highly varnished propeller with serious brass leading edges heading a curious oval-shaped radiator, with finely-crafted Venetian blinds. Huge cowls in battleship grey cover the most glorious example of Rolls-Royce V12 early combustion engineering. Long black exhausts flank the boxy fuselage, strangely ovoid in plan and elevation. The horizontal stabiliser moves for trim and is surmounted by the prettiest, surely too small, but racy-looking teardrop-shaped fin and rudder. The whole character fuselage is suspended between a pair of enormous thin wings, separated by eight substantial interplane struts. The gear looks somewhat narrow for the wingspan and the tubular steel hoops under the lower wing look ominously as if ready for an inevitable groundloop.

The cockpit sports a nifty little aero screen surmounted by a telescope sight for peering at the enemy. The top wing is crowned with a nautical-looking compass. The cockpit coaming is finished with a substantial leather roll, presumably to stop the pilot breaking a fingernail or being scalped. The panel is dominated by the cocking handles of a fixed Vickers machine gun, which passes through the main fuel tank, the V of the twelve cylinders, a hole in the radiator and thereafter avoids putting shells through the prop by means of an ingenious hydraulic interrupter gear, named after a Romanian gent by the name of Constantinescu.

The wooden dashboard is scattered with exquisite instruments, one of which tells your time, another your height, another your speed and the rest whether your motor is happy or complaining. A viper's nest, posing as a 'fuel selector panel', looks firmly designed to catch the unwary. More like a Victorian petrol experiment in serpentine brass, with a nickel-plated air pressure relief valve, obscurely scripted engravings indicate this myriad mess of little brass cocks and levers. Surmounting the mystery is a splendid brass fuel pressure hand pump with a wooden walking stick grip, close enough to the cockpit coaming to take the back off your sheep­skin gloves.
The pilot is seated on top of an auxiliary fuel tank, in a wicker half-Fortnum & Mason hamper Mark 1 made for the intermediate set of buns. God knows how one got in with the period sheepskin leggings and three-quarter-length coat. With suitable cord bindings and leather straps, the stick and rudder are Bentleyish in construction, as indeed are the throttle, mixture, advance and retard. The trim lever operating the stabiliser is a hefty piece of kit, which would not look out of place in a 1920s' steam locomotive. The radiator shutter lever is equally quaint but effective.

Behind is the gunner, situated in the middle of a rotating Scarff ring with a highly pivotal Lewis gun and its ingenious Norman vane sight. He sits comfortably on a plank of wood, which in turn straddles a reserve ammunition box-battle damage being of minor concern.

After ten years of meticulous restoration work, tramping the world to find the right bits, countless debates to progress the project and continuous assessment of each fine incremental step toward flight readiness, she was now finally ready for me and I was not ready for her.

Perhaps it was the sense of relief that a torrent of hard-earned money had temporarily stopped flowing into this aviation monument… possibly the realisation that I could give an accurate costing of each constituent part of the aircraft and recall each step of the complex negotiations to obtain the rare items incorporated… possibly the recall of countless pilgrimages to contractors and sub-contractors- but, somehow, I had stupidly failed to learn anything substantial of how it might fly. I confess to faint recollections of an experienced portly chap warning of "the deadly crossed controls" and another russet gentleman kindly writing abbreviated handling notes (five lines), mostly starting with 'Do Not… '

Fortunately, at that moment Peter Kynsey appeared, followed by Stewart Goldspink, both gentlemen having uncanny instincts for when hangar doors are about to open. I suspect they had earlier made arrangements that ensured my strategic absence and the Brisfit's availability for them to conclude the test flying.

Despite misgivings about weather (improving), my lack of Bristol-based baggage, with two experts for briefing and some expansion on the 'Do Nots…' plus a few 'Do's…' it was time to saddle up. Leather jacket, leather helmet (no radio), leather boots, leather gloves, leather scarf (… well not really). Mounting the beast for real seemed infinitely more complex than the occasions I had climbed aboard the project for a little inspirational hangar flying. The advance and retard lever needed to be in retard, like me. Both sets of magneto switches were off, as we rehearsed the starting drill, so that I neither decapitated nor unnecessarily fatigued the triplex start team.

The attending experts had not flown it on such a cold damp evening, so it needed oodles more prime than briefed. Much credit is due to the vigour of the prop team. I leave all the dinky little Victorian brass cocks of the fuel system exactly where I last left them. A further load of fuel pumping, "Contact" is yelled, a flash of hands and suddenly I am sitting behind the sweetest turning, elegantly purring aero engine you can imagine.

Meanwhile, my leather helmet and goggles were being blown off my head, which sat higher than the aero screen and was neatly intersected by the upper mainplane. My left knee was operating the advance, which needed to be in retard and the right unnecessarily activating the trim. Was I wetting myself? No, the excess of unlocked primer fuel was dripping onto my parental equipment - we did not need a fire in the immediate future. Having decided that in 1917, Bristol ergonomics were probably not an advanced science, or that most WW1 pilots were of the Shetland variety, evidenced by our worthy experts, I threw out the meagre leather cushion, slid my buns forward, crouched behind the screen and with temps and pressures rising normally (including mine), waved away the chocks with a 'confident' air.

One downside of the briefing was that I would now have an expert audience. I also overlook to mention that various brave souls of both sexes had offered their bodies as ballast in the gunner's compartment. Not anxious to reveal my incompetence to others, nor subject them to my learning curve, I sagely ignored the women beseeching me, accepted water ballast and made a note of the 'leverage' available for future flights.

My wing-walkers, having recovered from swinging the prop, now had alternate bursts of trotting and walking as I learned to taxi the beauty downwind. Flushed despite the cold, they were waved away by me as I made a visual scan of the empty circuit and took a green from the Tower. A quick pump to ensure fuel pressure, simultaneous ignition advance and throttle plus judicious opening of the radiator blinds. Miraculously, this giant melange of spruce, wire and Irish linen cocked itself accurately into wind, put a wing down with the torque from its sweetly bellowing Rolls Falcon III and simply went flying, in less than 100 yards.

At the end of the airfield I had circuit height and banked gingerly, mindful of the deadly crossed controls". The inverted slip-ball works the opposite way to nowadays and the monster ailerons produce buckets of adverse yaw but, despite its debutant captain, the Brisfit made a creditable first climbing turn.

Down wind, I kept ascending and base legged toward the centre of the airfield passing through a surprising 2,000 feet QFE, everything still in the proverbial green, apart from my body temperature, which was in the deep blue. At four thou', under the edge of the unnecessarily largest
TMA in the world and away from the more leaden bits of sky, I felt comfortable enough to try more aggressive turns - which I admit required some considerable co-ordination (my compliments to the Shuttleworth display pilots). Slow flying and stalls power-off are most benign, although power-on stalls produced a few grins. I know not whether to blame my fuel-soaked parentals, the onset of hypothermia, lack of experience, or uncharacteristic prudence in front of the experts, but I now had highly developed homing instincts and put off trying any aerobatics.

Running off height without overcooling the engine proved a slight challenge but soon I was in a sensible downwind position with no traffic, to try landing before my peers and the growing crowd of curious. Slightly too high, as ever, I felt comfortable enough with the Bristol's characteristics to side-slip onto a low flare and, luck of the Celts, such a short field greaser that I felt obliged to go around again and tempt repetition.

Flushed with success, I turned early and low, entered downwind much closer to the airfield and remained high on base leg with a curving WW2-like descending turn to short final and, with great glee, another greaser. Time to quit whilst it still looked good.

Having shut down, amidst a babble of questions, my first impressions were:
•What a privilege to fly an 80-plus years-old WW1 fighter
•What a splendid aeroplane
•What a tribute to the restoration team
•What a dumb day for a first flight
•What a dumb way to prepare oneself
•What a climax to a long, tortuous and expensive adventure
•God am I pleased
•Jeez am I cold
•Man, what a magnificent piece of kit, and
•Where can I get sheepskin leggings?

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#7 Millst0ne

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Posted 12 November 2010 - 12:39

wow! that would be good in ROF!


ID love to fly it!
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#8 Endy

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Posted 12 November 2010 - 13:24

Yes, one of my fovorite WW1 planes.

Question — does anyone know what the black curved bar is, just above the joystick?

Thanks for posting by the way.
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#9 Viper69

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Posted 12 November 2010 - 14:37

Looks like some tubular bracing.
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#10 piecost

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Posted 12 November 2010 - 23:34

Yes, its a steel tube brace of some sort
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#11 piecost

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Posted 15 November 2010 - 17:13

Bristol Fighter trim curve
Roll-rate, yaw-rate and sideslip versus incidence [not necessarily a Bristol Fighter]
Bristol Fighter Rudder angle to Trim with different throttle settings


Extract from:

Proceedings of the Seventh Meeting, Second Half, 61st Session.

THE TAILLESS AEROPLANE, Captain Hill

"…Let us now examine how well, or ill, we are served by the controls fitted to the normal aeroplane; for convenience the whole control system may be divided into its three components; longitudinal, lateral and directional.

(i) Longitudinal. Fig. 1 shows a typical example of the variation of elevator angle with incidence; it refers to a Bristol Fighter when gliding, and it will be remarked that at 19° incidence, just beyond stalling point, the full limit of the control has been reached; and while there is a good margin of control at all normal speeds, say down to 52 m.p.h. which is about 14° incidence, yet as we go below this speed, the whole of the available control is used up in maintaining trim. Thus the range of possible attitudes for steady flight is strictly limited, and should for some reason the aeroplane become stalled, the elevator control will be ineffective; in other words, the aeroplane will be out of control.

FIG 1. Bristol Fighter. Elevator Angles Gliding

(ii) Lateral -Apart from counteracting the engine torque, which is small, no portion of the lateral control is eaten into by the requirements of trim; The next question therefore is how much control is required for maintaining the rates of roll, yaw and sideslip which constitute "good manoeuvrability"? Fig. 2 indicates the rates of rotation and sideslip, in a non-dimensional form, which may be expected from the normal control system if a straight flight can be maintained, as is the case below the stalling angle.

Confining ourselves at first to this range of angles below stalling, we know from practical flying experience that an aeroplane having the characteristics shown in Fig. 2 is under good control, and we may therefore co-ordinate the test results with common language by saying that motions represented by the diagrams constitute" good manoeuvrability."

FIG 2. Lateral Control of Aeroplanes of Conventional Type. [Not stated to be of Bristol Fighter]

Proceeding now to a consideration of the motion at and after stalling, we are faced with the more complex state of affairs due to the interaction of the lateral and directional controls, which now may render straight flight, the basis on which the diagrams in Fig. 2 are founded, impossible. This interaction of the controls is fairly clearly understood and arises from the fact that the normal type of ailerons, when set over to produce a rolling. couple, also produce a yawmg. couple; if this yawing couple cannot be neutralised by the rudder, then the aeroplane will yaw, and its act of yawing will tend to roll it against the ailerons. At normal angles of incidence, i.e., well below stalling point, the tendency to yaw is small and causes no trouble, but near and beyond stalling the undesirable yawing couple produced by the ailerons is so large as to overcome. anything which the rudder can cope with, with the result that the ailerons are ineffective as an organ of control.

(iii) Directional. A small rudder angle is usually required to maintain straight flight. The reason for this is that the rotation in the propeller slip­stream causes a lateral force on the fin, and the turning tendency thus produced must be counteracted by setting the rudder across. Fig. 3 shows the angles required on a Bristol Fighter under different conditions, and it will be seen that they are small compared with the maximum rudder angle, which is 35º

FIG. 3. Bristol Fighter Rudder Angles

Thus, as with the lateral control, so we find with the directional control, that nearly all is availab1e for the maintenance of definite rates of roll, yaw and sideslip. The required rudder angles for a normal aeroplane are shown graphically in Fig. 2.

As before, we will first examine that part of the diagrams below the stalling angle. It will be seen that the rates of motion described above as "good manoeuvrability" are within the capacity of the rudder, and the control is satisfactory. Above stalling, however, there is a large region between 20º and 30º incidence in which is required a rudder angle greater than the maximum of 35º. This of course means that the rudder control provided is insufficient to maintain straight flight when rolling.

(iv.) Influence of Stability on Contro1. No discussion of the control of an aeroplane would be complete without some reference to the influence of stability on the margin of control which is required for safety. No one has yet succeeded in putting this subject on a quantitative basis, thus we are thrown back to a more general survey; perhaps the best plan is to concentrate at first on the most important aspect of the problem, viz., the lateral instability which occurs after stalling, including the phenomenon of autorotation. On reference to Fig. 2 it will be seen that between 20º and 30º incidence for 0º aileron angle there are two possible values for the rate of roll and the zero value, i.e., straight flight, is an unstable value. The instability in flight associated with this condition is most violent, and I suggest that it is when in this state of instability that wind gusts are responsible for their most evil effects. It is a notorious fact that normal aeroplanes which can be flown stalled with fair success in dead calm air become uncontrollable when stalled in bumps. One lesson to be learnt from this is that ceteris, paribus, more powerful controls must be provided where there is instability, but the more useful deduction is that it is better, if possible, to avoid
the instability.

(v.) Summary. Summing up, we are faced with the conclusion that while the controls of a normal type of aeroplane are adequate so long as the stalling angle is not approached, they all become ineffective in stalled flight while at the same time serious lateral instability develops."

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#12 piecost

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Posted 15 November 2010 - 17:25

Bristol Fighter Rudder Effectiveness versus Incidence

See: Data Topic for Airplanes Performance. Post No. 40
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#13 piecost

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Posted 16 November 2010 - 17:47

Influence of Propeller rotation on pitching moment versus incidence for Bristol Fighter

Taken from: Proceedings, Fifth Meeting, Second Half, 62nd Session, THE JOURNAL OF THE ROYAL AERONAUTICAL SOCIETY: THE SPINNING OF AEROPLANES

7.6 The Pitching Couple due to Rate of Pitch

m_q, the pitching couple due to rate of pitch, is of some imiportance in the balance of pitching couples in a spin, since, as we have seen, q, besides being appreciable in a typical spin, my have either sign.

FIG 21

We are dependant for the estimation of this quantity on tunnel measurement of the rotary derivative M_q by the oscillation method. This applies in strictness only to small values of q, but as the rate of pitching moment in a fast spin is never great, the application to spins may be a fair approximation. M_q has been determined for incidences up to 35º on a 1/5 scale model of the Bristol Fighter. In applying these results we must assume that m_q is proportional, at a given alpha, to qS/V, according to the formula:

(V/qS) (m_q) = (1 / S s^2 rho ) ( M_q / V)

Fig 21 shows values of (V/qs)(m_q) for the model with the airscrew removed and also with the airscrew running in the high speed condition. It was observed in the course of the experiment that the decrease in (V/qs)(m_q) at stalling is largely an effect of the wings, the moment from which is actually positive at stalling.The tail provides a moment which is roughly constant at all incidences.

The increase in (V/qs)(m_q) whjen the airscrew is running is an effect of the increased velocity over the tail.

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#14 piecost

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Posted 16 November 2010 - 17:48

Aileron Rolling and Yawing Moment for Bristol Fighter at high incidence


Taken from: Proceedings, Fifth Meeting, Second Half, 62nd Session, THE JOURNAL OF THE ROYAL AERONAUTICAL SOCIETY: THE SPINNING OF AEROPLANES


7.7.3. The Aileron Control- Ailerons at least those of the conventional type differ from elevators and rudder in providing a couple which varies in direction as well as, in magnitude with aileron angle, incidence and rate of rotation, and above the stall the axis of the couple is far from that coincidence with the chord axis, which would complete the ideal triad of controls, one about each axis of the body system. This property of conventional ailerons, an example of which is shown in Fig. 24, makes it very difficult to assess their action in relation to a given manoeuvre.

…It is there established that the yawing moment of conventional ailerons is, above stalling, such as constantly to stultify the use of the control as a producer of rolling moment. For instance, if the ailerons are used to check a given rate of roll, the yawing moment initiates a cycle of changes which ends in increasing the rate of roll. It is not surprising in face of this complication that aileron action in the rapid rotary motion of spinning is at present very little understood. Most pilots appear to be in agreement that the ai1erons are of little use in recovery. The only well documented fact that has come to light is that it is in general easier to spin with conventional ailerons crossed, i.e., set so as to oppose the rolling motion of the spin. The reinforcement of the' rudder by the yawing moment due to the ailerons when the controls are crossed results in a more rapid spin at higher, incidence, although the ailerons are producing a rolling couple tending to reduce the rate of roll.

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#15 piecost

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Posted 16 November 2010 - 17:51

Breakdown of Pitching Moment versus Incidence of Bristol Fighter

taken from: Proceedings, Fifth Meeting, Second Half, 62nd Session, THE JOURNAL OF THE ROYAL AERONAUTICAL SOCIETY

THE SPINNING OF AEROPLANES

BALANCE OF COUPLES FOR BRISTOL FIGHTER AND B.A.T. BANTAM

We are now in a position to collect the various component couples of which a survey has been given and to attempt their balance. The Bristol Fighter and RA.T. Bantam aeroplanes are convenient examples to take because, besides being well known and contrasted types of which the first has proved safe to spin and the second very dangerous, a fairly complete collection of'model data exists for each.

The differences, most relevant to the present discussion, between these aero­;planes are:­

(a) The Bristol Fighter has a positive stagger of 18°, the Bantam has zero stagger.
(b) The inertia couple coefficient is in the Bantam more than double its value for the. Bristol Fighter at given a and ps / V.
© The decrease" in rudder efficiency at large incidence is much more pronounced for the Bantam than for the Bristol
(d) The Bantam has the more backward C.G; 0.40 compared with 0.35.

8.1 The Equation of Pitching Couples

8.1.1. In. the pitching equation:­

m_i + m_i1 + m_alpha + m_eta + m_q + m_p + m_v = 0

We have already considered every term except m_p and m_v, the contribution from rate of roll and sideslip, both of which ae of secondary importance

The sideslip effect on pitching moment has been investigated on models of several different aeroplanes. For incidence above stalling m_v is nearly always positive, it is greatest just above stalling, it is almost negligible unless Beta [sideslip angle] exceeds 10º and it is mainly an effect of the tail unit. As to m_p, we should expect that the influence of rate of roll on pitching moment would be drawn both from the wings and the tail unit. Observations of the wing contribution have been made in one or two cases, but there is no experimental evidence regarding the tail. The value of this quantity is therefore rather conjectural, but it is not of great importance except in extreme cases. Figs. 27 and 28 exhibit on two diagrams, one for each aeroplane, the various pitching couples set out above. The Bristol' Fighter diagram shows, between alpha=20 and 35:­

m_i for ps/V = 0.3, 0.5, 0.7
m_i1 for airscrew rotating, engine off, in a sense opposite to that of the spin.
m_alpha for h=0.35, alpha_T (the tail setting) = -3°.
m_eta for eta=20º (rudder angle)
m_q for qs/V = 0.1 and –0.1
m_v for Beta = ± 20º
m_p for ps/V = 0.5 (this is an outside estimate)

In the Bantam diagram m_i1 is missing and m_alpha is for h = 0.40

8.1.2. These diagrams show very clearly the importance of the inertia couple in the group of pitching moments. Consider for instance the Bristol Fighter diagram, Fig. 27; If we exclude for the moment the damping couple m_q there is no positive aerodynamic couple of any magnitude to balance the large negative value of m_alpha except the control. The possibility of balance appears to depend to a large extent on the sign of the damping couple, i.e. on the sign -f q. We have already seen that there is no theoretical reason why theta should not exceed 90º, and values exceeding 90º are consistent with several observations of full-scale Bristol Fighter spins. When theta is greater than 90º, q is negative and m_q is positive. Curves of m_q corresponding to qs/V = +0.1 are drawn on the diagram.

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#16 piecost

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Posted 04 January 2011 - 15:26

Aer0plane, Nov 2006

The Bristol Fighter World War One's Mosquito ?

This standard 1918-production F.2B, D8096, was one of two acquired shortly after the war by my near namesake, C.P.B. Ogilvie. Intending to restore it to flying health, he had it registered as G-AEPH, but he made no progress. Ogilvie had an understandably stubborn desire to retain his prize piece, but as he lacked the resources to restore it to airworthiness he was eventually persuaded to part with it by the late Leonard ("Jacko") Jackson, then manager of the Shuttleworth Collection. Subsequently the air­frame returned to its original home, the Bristol Aeroplane Company, for restoration, while its Falcon III engine received comparable treatment at its Rolls-Royce birthplace. The two were then reunited, and the born-again Bristol Fighter flew from Filton on February 14, 1951. A second engine was overhauled by Rolls-Royce apprentices, inhibited and displayed statically at Old Warden for availability as a spare.

Before we move on to the flying aspect, readers may be interested in a directive surprisingly issued in June 1924 by the Air Ministry, which at that time handled matters relating to both Service and civil aviation. This states that no Certificate of Airworthiness for a Bristol Fighter will be issued or renewed until the I-section front spars on the top mainplanes have been strengthened by gluing and screwing half-inch three-ply to their undersides. In Part One I mentioned the report by the commanding officer of 48 Sqn (the first Royal Flying Corps operational unit to receive the type, in April 1917), stating that they dived vertically to a speed estimated as 230 m.p.h. I have found no stories of battered wing­less Bristol fuselages strewn over the fields of France as a result of the subsequent pull-outs, so what caused this late panic? It seems even less relevant in the post-war years, when extreme speeds and violent maneuvers were less likely.

Now let us look at the Bristol F.2B as a flying machine.

Already two features had sunk in. The very large two-bladed propeller left relatively little ground clearance, so it would be important not to lift the tail high on take-off; and below the instrument panel was a complex of pipes and taps that controlled the pressurisation of the fuel system. The former was easily manageable, but the latter took time to assimilate. I wondered how, in stress of battle, a pilot finding a drop in pres would be able to think sufficiently coolly to play the taps in the right sequence, which was critical. Apparently, though, if the engine pump and a wind-driven pump misbehaved it was possible to continue flying at low power, relying on gravity feed from the main of the two tanks. (Luckily I never needed to prove that.)

Apart from the fuel system the cockpit has just seven instruments arranged rather haphazardly on the panel, and the view outside is better than that of many biplanes, for the fuselage is positioned midway between the upper and lower wings.

Starting the engine, after pumping up the fuel pressure, calls for two or three prop-swingers operating in harmony with linked arms, as the Falcon's compressions are too strong for one person to overcome. The pilot's procedure involves energetic winding of the handle for the starter magneto, but this needs careful co­ordination with the workers outside. Alternatively, the engine may be fired into life by means of the Hucks starter, a mechanical device mounted on a Ford chassis. Once running, the Falcon sounds, feels and is purposeful. The only difficulty is the position of the magneto switches, which are not only outside the cockpit but out of view!

Taxying calls for wing-walkers, as the F.2B's large slab-sided fuselage gives it a strong determination to turn into wind, with no brakes to prevent it from doing so. Take-off is impressive, with a rapid acceleration and less tendency to swing than one might expect. It is airborne after a very short run, especially if care is taken to keep the tail fairly low to prevent a propeller scrape. Although rate of climb is one good measure of an aeroplane's value as a (useful fighting) machine, in the interests of the Falcon's age I avoided a full-throttle ascent and turned to published records for the answer, but the results were frustrating. I found figures varying from 875 to l,300ft/min, but, as no weights were quoted to check whether these were comparable, I was barely any the wiser. From "feel", I am sure that the higher figure is nearer the truth.

In normal flight the rudder is relatively light and the elevators are even lighter, but the ailerons are unexpectedly heavy, needing two hands at higher speeds. Perhaps the most noticeable feature of the Brisfit's handling, though, is its behaviour in turns, which must come as a surprise to any pilot with a relatively modern mind.

On more recent aeroplanes the ailerons operate differentially, which means that a down­going control (on the outside of the turn) moves less than its opposite partner travelling upwards, but there is no such luxury on the Brisfit. As a result, an attempt a turn on ailerons alone, or with insufficient use of rudder, causes the machine to bank correctly but to change heading in the wrong direction. This is because the full­travel down going aileron generates drag when it is least needed; so to keep the aircraft in balance and achieve the desired result calls for generous use of the feet/ preferably applying into-turn rudder slightly before moving the control column in the same direction, This must have added to the problems of accurate gun sighting, but the successes achieved prove that the pilots of the day knew what they were doing.

When becoming familiar with a new type, a pilot is wise to discover how it behaves at slow speeds, especially before carrying out even the mildest form of display. With a Shuttleworth aeroplane, in particular, this must be done at the earliest opportunity, for (very rightly) no flying time can be wasted. Perhaps I was fortunate to be able to fly the Brisfit twice before my first public appearance on type, but I was pleased to find the aircraft's conduct impeccable. From several different styles of approach to the stall, a gentle buffet preceded an equally mild break-away/ with only a modest tendency to drop a wing.

As a high-drag aeroplane the Brisfit is not very fast. The published maximum speed is 125
m.p.h. at sea level, only 5 m.p.h. below the permissible limit on the Shuttleworth machine/ but this is no handicap in the relatively gentle demonstrations that are the order of the day. A large trim lever on the right side of the cockpit serves well to relieve fore-and-aft loads between different airspeeds. It is important throughout a flight to keep constant checks not only on the oil pressure, but also on the fuel pressure and coolant temperature, the last of which is controllable from the cockpit by use of radiator shutters.

The landing is critical, and it is important to do this as nearly as possible into wind. The final over-the-fence approach speed is a very modest 55 m.p.h. and with a touchdown at about 40 m.p.h. and a helpful tailskid, the subsequent ground run is very short, though still long enough to display a tendency to swing into a ground loop. The Brisfit gives its pilot a pre-flight visual warning of this for there are hoops under each lower wingtip to prevent it from scraping the ground on the way round.

Some aircraft are best forgotten, but the Bristol Fighter is one that leaves a favourably positive mark on the memory. In a critique of its pure handling qualities, it lacks well co-ordinated flying controls, but this is compensated by a number of matching virtues. By measurements of its time it was (and fortunately still is) a big and powerful “adult” aeroplane that called for and received a high level of respect.
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#17 piecost

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Posted 07 January 2011 - 12:43

taken from: British Aviation, The Great War and Armistice 1915-1918 by Harold Penrose
page 284

Years later I flew the final version of the Bristol Fighter as my first Service type. Compared with the Bristol P.T.M. on which I had learned, the wings seemed enormous from the cockpit, and massively boxed by struts and wires. Though the centre-section hardly impeded the vista above and ahead, one could understand the recurring war-time criticism that the lower wings of machines like the D.H.9 and the Bristol Fighter obstructed immediate downward view for reconnaissance; though the D.H.9 was worse because the pilot was farther behind the wing, whereas in the Fighter he saw steeply over its leading edge, and the R.E.8 was better still.

We had no parachutes; cushions were piled high on the upright basket seat to give enough forward view. Beneath the seat rested the rear fuel tank, and a forward gravity tank was under the fairing in front of the pilot. The instru­ment board was simple, with ASI, altimeter, side-slip bubble, revolution indicator, oil pressure gauge; on the centre-section rear spar was a small eye-level compass with degree scale fixed peripherally on the needles. A wind-driven pump maintained 3lbjsq in pressure in the main tank, but if it failed there was a stand-by hand pump mounted slantingly in the cockpit. To a novice pilot the petrol system seemed intimidating as there were six cocks controlling air pressure, and the instruction book baldly stated: "If either tank is allowed to empty during flight, the air pressure is released, the air passing to the carburetors, thus starving the engine and causing serious risk of carburettor fire. The pressure gauge was therefore the object of constant attention.

Having checked that wheel chocks were in place and mechanics either side were holding down the tail, the simple cockpit drill was to ensure switches off, set the trimmer, waggle controls for freedom, crane downward at the fuel gauge on the top of the rear tank, turn on appropriate fuel cocks, and pump up pressure. The big propeller was pulled round by a couple of men while the pilot primed the engine with a small 'Ki-gas' pump. Half a dozen turns and they were waved clear. Swinging the prop was de trop, for the engine featured a hand-starter magneto which was spun vigorously with main switches on. There would be a convulsive kick and a grating rumble, then a continuing and distinctive chatter from the gear-box as the propeller whirled into an easy tick-over.

A few minutes warming and a run at full throttle while the mechanics sprawled over the tailplane with overalls streaming in the slipstream, then chocks and crew were waved away, and the Fighter, rolling slightly, taxied out, turning cumbrously at bursts of greater power for added slipstream on the vigorously angled rudder. Taxi-ing up-wind was easy, but unless there was a mere breeze, down-wind was another matter with a man at each wing-tip to prevent swinging wildly, though skilled pilots could manage at slow speed, using sharper, shorter bursts of engine.

Turning into wind, one stopped, surveyed the sky behind and the ground ahead to make sure no aeroplane was near, then opened up. With stick well forward to lift the tail, the Fighter ran like a magnificent eagle, sailing into the air in stately fashion at merest hint of backward stick from the pilot. We might gasp for breath in the thundering gale of slipstream, but she flew with steady precision, stability adequate, response to controls easy and confident; though as speed increased the ailerons became rapidly heavier and on attaining 150 mph in a dive it took considerable strength to move the stick sideways, giving false impression of slow response. It was not aided by the exposed and flailing control cable between fuselage and outer wing-bay. Nevertheless the Fighter called for aerobatics. By trial and error I learned how to loop and roll and spin, and the machine always responded with easy confident steadiness.

In those days it was regarded as a breach of faith to 'rumble' the engine during an approach, for the glide gave a comfortable and commanding angle, and with a little excess speed near the ground the machine would steadily float while the tail was gently lowered to hold off, resulting in remarkably consistent three­point feather-light landings, despite the undamped shock absorbers. Yes, we loved the Bristol.

The Experimental Flight of the Royal Aircraft Factory was endeavouring to put handling assessments of aeroplanes on more scientific basis…

His group of pilots agreed that the Bristol Fighter had pleasant lateral control, but they found the machine difficult to roll with the original small rudder. One reason suggested for the pleasantness of the Fighter was that it differed from machines like the, R.E.8 in having a more comfortably disposed cockpit, with the hinged bottom of the control stick farther forward and the pilot's legs unrestricted sideways, thus giving greater lateral freedom of stick movement and con­sequently greater maximum control.
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#18 piecost

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Posted 12 January 2011 - 18:10

Taken from:

ИPI’ in the Sky, A history of No. 22 Squadron, Royal Flying Corps & R.A.F. in the war of 1914/18
, by W.F.J. Harvey, M.B.E, D.F.C.*, T.D. (privately published 1969)

APPENDIX VIII, THE BRISTOL FIGHTER

A curious feature of the types of British aircraft of 1914/18 was there marked individuality (like so many of those who flew them). 'Stick and string' they are dubbed now by those who confuse the pre-19l4 products with those of 1918, and fail to realise that four years showed development which might have taken forty in peacetime conditions. Stick, string and doped linen they were, but all were very different and the latest ones, at least, were a triumph of design against stress and strain.
Some were hated; some, like the pretty kittenish Sopwith Pup, loved; some, and the old workhorse F.E.2b., respected for their sterling qualities -The Farmans were funny jokes; one or two others were jokes in rather poor taste. And there was the Camel, that fantastic brainchild of Sopwith, which was both feared and respected. There was only one was both respected and loved - the Bristol Fighter

Much has been written about the Bristol, most of it by those never lucky enough to take one off the ground; some by those who flew them in peacetime conditions but never in their natural element of twelve to twenty thousand feet where their true qualities became apparent. This was classic aeroplane, in looks, in performance for its period, and of a curiously perfect tactical design at a time when the future requirements of a fighting aircraft were not fully understood, nor the strategy and tactics of fighting in the air fully developed.

During the spring of 1916 Captain F.B. Barnwell of the Bristol Co. designed a reconnaissance biplane, the R.2a, as a two-seater replacement for the Royal Flying Corps. The120 h.p. Beardmore engine for which it was intended was found to be insufficiently powerful and the project was temporarily shelved. Later that year a scaled down of the Rolls Royce 'Eagle' engine, designed early in 1915 by Henry Royce and his assistant A.G. Elliott, became available; Barnwell immediately remodelled the R.2a for the new engine, and. the Bristol Fighter was born.

The revised design was named the F.2a and work on two prototypes began in July 1916, the first teat flights taking place on September 9th when a ludicrous incident caused by a faulty altimeter persuaded both Bristol's and Vickers’s test pilots for an hour or so that the machine could not climb above 6,000 ft. Both prototypes exceeded estimated performance by a large margin and 50 F.2a.s were ordered and sub-contracted to the Tramways works at Brislington. At this point it was decidedl to cover the open structure of the lower centre section and, more important, to slope down the horizontal portion of the upper longerons forward of the rear cockpit. Not only did this result in a narrowing of the engine cowling and therefore a small blind spot ahead, but the cutaways on the sides of the pilot's cockpit enabled him - if he card to take the trouble - to see and take measures against the unnerving habit of hostile aircraft, particularly the Fokker Triplanes, of creeping up underneath. 200 of this modified design were ordered and became the final F.2b.

The growing pains of this matchless aircraft were unusually protracted. Not, only were there alterations and modifications common to a new type, but there were strikes which held up supply of airframes, and Governmental refusal until nearly too late to accept the forward looking advice of Claud Johnson, managing director of Rolls-Royce, for expansion of engine production necessary.

Fairly docile and well mannered in skilled hands, the F.2b. no dual control, and early flights by those converted from the slow and stable B.E.2c. or rear engined Farmans and F.E.2bs were perilous. Many accidents during training and the usual rumours of a new type's structural weakness gave the machine an unwarranted bad reputation, and No. 48, the first squadron to be equipped, which reached France in March 1917, was thrown unprepared into the disastrous air war of that spring. Its losses were such that Von Richthofen declared "The new British aeroplane was not to be feared.” So bad had its reputation become by the late in training had to be urged to volunteer for transfer to the Bristol.

One way and another, production rate of machines and pilots was than sufficient to replace losseS9 But, slowly, Nos. 11, 20 and 22 [may be some missing text here] squadrons serving in France had their obsolete F.E.2bs replaced by Bristols in the summer of 1917, losing heavily while learning to handle a different tactical arrangement of aircrew, and with difficulties in maintenance of a new type airframe, engine, gun and gun gear. Delay in equipping these squadrons and the sorry story of early build-up are shown in the production figures quarterly from December 1916 to December 1918:­ 12-40-80-138-207-346-543-749-986

The last setback occurred during the winter of 1917/18 when the use of inferior timber enforced by the United States embargo on their export of silver spruce and Port Orford cedar resulted in wing collapses of several new machines. Reinforcement was done by squadrons in France the Bristol came into its own, the genius of its designer vindicated.

[this text inserted from a different part of the book] But there was a dark side to improved performance. Near the end of the year, the first cases of Bristols collapsing in the air occurred, and for a time pilots flew cautiously straight and level, with the exception of Lieut. Oades who threw his machine about recklessly to maintain morale. The cause reached back to America's official entry to the war in April 1917 when, in aid of an optimistic programme of building 20,000 aircraft by early 1918, an embargo was placed by the U.S. on export of silver spruce for airframes. The second grade timber which Bristol Aeroplane Company was forced to use after first grade stocks were exhausted proved inadequate for increased horse-power and higher speed used in manoeuvre. Under advice from the Company, squadron riggers stripped and strengthened the wings, one by one, and after the last collapse in early February there was no further trouble. [this text inserted from a different part of the book]

Squadrons used the comparative quiet of the air war during that winter in target practice (including an aerial gunnery inter­squadron competition at Berck, in which No. 22's three Flights took the first three places), and in strict training in the formation flying which Kitchener had insisted on in 1914. It was realised that the proper use of the Bristol was in formations of four or five, open and individual in offence, and closed up in defence so that all rear gunfire was concentrated. The strategy and tactics of two-seater fighting were worked out by young flight commanders who had survived their first 30 or 40 shows, and without advice from above. Bristol pilots were not considered eligible for fighting instruction at Turnberry or Marske - such as it was ­ and the only instruction given to the present writer, for one, was aimless circling another machine during training, camera gun practice against a level flying target aircraft, and the receipt in 1918 of a pamphlet 'entitled 'Fighting in the Air' and dated early 1916.

The accepted legend that Bristol pilots turned their Wholly unprotected backs to the enemy so that the rear gunner was left to duel with, an adversary partly protected by the engine before him and with three times the fire-power is very contrary to the spirit of pilots one remembers.

It is true that in an air war conducted over enemy territory there often came the moment when shortage of fuel and the prevailing west wind made it necessary to turn one's back on the enemy for home. This is where a well trained close formation was impregnable except against a suicidal enemy, and the reason why Bristol offensive patrols, escorts and reconnaissance’s penetrated deeper than the single-seaters.

So, throughout 1918 Barnwell's F.2bs played a full part in the air war of that year, were a sure shield to those whom they escorted and when properly handled, were looked at askance by the enemy even when deep into his territory. Nor was this respect confined to German pilots. On a day in August 1918 When, due to heavy losses, many SE and Camel squadrons had a high proportion of inexperienced pilots, a Bristol flight commander flying alone over the lines and wearing his leaders streamers, 'collected' successive formations of these until more than 60 were following him.

As a fighter, the setting of the fuselage between the wings and its knife-edge taper at the tail ensured the minimum of blind spots, which could be uncovered by the slightest of tail switching. The back to back seating of pilot and rear gunner, classic position of those fighting against odds, made possible instant change from offence to defence, and back again. So close was the seating that an experienced Bristol war flying pilot could be recognised by the scar across the back of his flying coat, caused by friction from the Scarff gun mounting. And the point of an elbow into the rear gunner's kidney would spur him to action quicker than any inter-com.

No. 62 Squadron arrived in France I in February 1918, being with No. 22 the only purely fighting Bristol squadrons normally without 1'econ­No. 88 a fourth F/R squadron followed in May. During summer the Long Range Artillery Co-operation Flights also received some Bristols, but engined by the deplorable Sunbeam Arab. No. 139 fighting in Italy was re-equipped, and No. I (Australian) Sq. in Palestine soon achieved air superiority over the German/Turkish air force in the desert. A number of Home Defence squadrons flew Bristols, and one of their pilots shot down over Joyce Green near Dartford during a German day­light raid may have been the first Englishman to be killed on English soil by an overt foreign enemy since 1066.

There were, of course, deficiencies in equipment. Twin forward firing Vickers would have; more than doubled offensive potential. Many casualties to rear gunners (often leading to loss of pilot and machine) been avoided by a sheet of armour at the rear of his cockpit. Rubber casing of the thin gauge petrol tanks which, under pressure of 2.5 to 3 1bs. p.s.i. opened out when hit would have reduced the number lost in flames. Heavy padding to the steel butt of the Vickers before the pilots head might have saved many lives in medium crashes; and simple fixed to the rudder wires which passed through the rear cockpit could, with the emergency stick, have helped many rear gunners with a dead or unconscious pilot to put their machine down without fatality. Even a first aid box might have been useful sometimes.

But it was not the habit of senior officers in those days to discuss the points of their aircraft with those who flew them in action. There was a tendency common with any war machine - land, sea or air ­ to add bits and pieces which reduced performance and ended with an hermaphrodite compromise. One well-meaning idea from higher command to attach bombs to this aircraft not designed for weight lifting and fitted with bomb sights. Enthusiasm reached the point when the last straw kept a Bristol earthbound; two 112 lbers. were dangerous flying; one 112 lber left it neither a bomber nor a fighter. And these bombs were usually jettisoned haphazard at the earliest possible moment. A more useful step would have been to re-calibrate the Aldis gunsights which remained at 100 m.p.h. for two years, although during 1918 many initial engagements took place at 150 m.p.h. or more, and many German pilots escaped by the skin of their tails. There follow a few items from the present writer's records not likely to be found in any official manual of the F.2b:­

(a) A flight of five Bristols with full war load reached 20,350 ft. still climbing in formation in July 1918, a tribute to the quality of the Flight mechanics. Cold and lack of oxygen ended the climb.

(b) A Falcon III powered Bristol without war load and 1 cwt. ballast in place of the rear gunner was able to maintain level flight near ground with six of twelve cylinders out of action.

© A Bristol left uncontrolled with tail plane set neutral and throttle slightly open, descended from 16,000 ft. in a series of letters 'J', of which the verticals were 4,000 to 5,000 ft.
(d) From the observed behaviour of the ASI which circled two and one third times before breaking, the speed of a Bristol dived with full engine was calculated by the wise men of Filton at between 234 and 245 m.p.h., possibly a world speed record for an aircraft which returned. This machine survived a sharp pull-up. The rigging was somewhat deranged and the steel main member of the tail distorted.

(e) Another instance of the strength of the 'stick and string' Bristol was the difficulty found in breaking one which had an undiscoverable jinx in both engine and frame, and which undoubtedly would have caused the death of a crew, sooner or later. It took three 'landings' at 10 to 15 ft.up and with two unhappy 'volunteers' in the back seat to break a longeron, and so make the machine a write-off. The official ИMachine Report' gave the cause of crash as "Ran into an agricultural implement", an imaginative effort on someone's part.

(f) A delightful quality of the Bristol was the perfection with which it could perform the rarely seen 'falling leaf' acrobatic. After being put into the first sideslip with throttle nearly closed it would continue to slip to alternate sides almost without direction, and mixed with hovers and spins the series could be repeated with ease until landing out of a last turn.
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#19 piecost

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Posted 12 January 2011 - 18:19

From: British Aeroplanes 1914-18, J.M. Bruce

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#20 catchov

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Posted 13 January 2011 - 00:47

You deserve a medal piecost :) And just in time for the release of the RoF Biff (he says all hopeful like :oops: )
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#21 piecost

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Posted 13 January 2011 - 01:23

Thanks, but the information raises some difficulties in the modeling…

How will the RoF team implement the observer elbowing the pilot in the kidney ? :)
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#22 catchov

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Posted 13 January 2011 - 02:55

Elbow modelers of course :P

more power to your elbow
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#23 piecost

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Posted 21 February 2011 - 16:43

Accelerations & Air Speeds During Various Manoeuvres on a Bristol Fighter

February 1919 THE AERONAUTICAL JOURNAL page 59

By permission of the Controller of the Technical Department of the Department of Aircraft Production I am able to show three typical records, two of accelerations on a scout and a two-seater during a mock fight (Fig. 13) and one of acceleration during various stunts (Fig. 14). Many other experiments have been made, loops, rolls, spins, etc., being shown very beautifully.

This instrument not only gives us, in any circumstances, the resultant air force on the aeroplane - information which is essential for fixing a proper standard of strength - but it also measures the time of rapid manoeuvres. It is no exaggeration to say that it is one of the most valuable instruments for aeroplane experiments - and, indeed, for any other experiments where rapidly changing accelerations have to be measured that has been devised.

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#24 piecost

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Posted 21 February 2011 - 16:52

From Bleriot to Spitfire, Flying the historic Aeroplanes of the Shuttleworth Collection, David Ogilvy

The Bristol Fighter

Wing Commander R. F. Martin

In the course of the past twenty-five years, I have been lucky enough to have flown most of the aeroplanes in the Shuttleworth Collection. All of them, of course, are interesting, as they give an insight into the ways that past generations of designers and pilots evolved the handling qualities and performance of the aircraft of their time and the criteria by which they judged them. However, if
the truth were told, there is not all that much fun attached to flying some of the very earliest aeroplanes. Satisfaction - certainly. But one is usually far too concerned in not hazarding an irreplaceable piece of history to extract much enjoyment from the proceedings, bearing in mind the limited controllability and susceptibility to weather conditions of veteran aeroplanes.

Because it is free of so many of these anxieties and preoccupations, the Bristol Fighter is, perhaps, the aircraft in the collection for which I have the most affection. It was also, in the days when I first flew for Shuttleworth, the only aeroplane in which we flew cross-country to air displays. Like 'Peanuts', one was able to imagine oneself the World War i fighter pilot on leave from the Western Front, map reading one's way up the country to shoot a line to the locals.

My first cross-country, and indeed first flight in the Bristol Fighter, was from Old Warden to Newcastle (in 1952) with 'Jacko’,(l) in the rear cockpit. Now the cockpit is pretty basic. Throttle, mixture control, and hung below the quadrant, an advance and retard lever. On the right cockpit side, the elevator trim. Most of the other items are concerned with the fuel system. There are two fuel tanks, on one of which one sits; the other is further behind, behind the engine. a tank selector cock mounted on the left below the instrument panel which is somewhat obscurely marked, and on the right-hand instrument panel, a complex of brass pipes and taps controlling the pressurization of the fuel system. A priming pump and hand-operated pressure pump complete the system,

We set course from Old Warden to Sherburn-in-Elmet, where we planned to 'tech stop' and refuel, but over Leicester I changed tanks and the engine stopped. As I still had fuel in the tank on which we had been running, I switched back again and the engine picked up, but then followed a lunatic discussion of the problem with the 'Flight Engineer'. In order to make his views known,

'Jacko' practically climbed into the front cockpit and, without warning, wrenched up the side of my helmet and bellowed into my right ear. To prevent myself being deafened, I closed the throttle, so that he now only needed to shout, and in this fashion we glided down arguing at the top of our voices. Discussion then had to be abandoned while I climbed up, and resumed when the engine stopped as I changed tanks again, which 'Jacko' at last got over must happen if I kept turning the selector the wrong way!

A year or two later we had a period of mysterious engine failures. The bafflement lasted several months and it was amusing to see the number of experts who came to Old Warden to diagnose trouble only to retire discomforted. The symptoms were these:- the engine would start as readily as it had always done, and on run-up, rpm and magneto drops were normal. Airborne, the engine ran normally for about twenty minutes and then started to miss. If the magnetos were checked at this stage there was usually no dead cut, but of course the engine ran even more roughly on one magneto. It then progressively lost power until height could not be maintained and a forced landing ensued. Then the engineer would come along, start the engine and run it up. All normal 'Ground tested and found serviceable'!

My first encounter with this phenomenon was en route to a display at Waddington, again with 'Jacko' in the back. It was a gorgeous summer's day, and the engine having died away, we glided down into a convenient stubble field. While 'Jacko' prodded into the works, I lay sucking a straw in the sunshine. The only person to query the goings on was a farm labourer, who did not understand what it was all about but went away and kindly returned with a flask of tea. We were back in the First War era.

The cowlings replaced, 'Jacko' swung the propeller and the engine caught and ran up with no sign of a miss or a magneto drop. Setting course once more, it was again about twenty minutes before we missed a beat. In spite of all my juggling with the throttle, mixture and ignition, the power gradually dropped offand I made a one-eighty towards Leicester East, which We have had seen a little while previously.

In fact we only just made it downwind and with two feet to spare over the hedge as the power died away completely. The story of how we hitch-hiked ignominiously back to Old Warden in the back of a Fairchild Argus must keep for another day.

As it seemed highly unlikely that both ignition systems were failing at the same time, all the early efforts to diagnose the problem were concentrated on the fuel system. Eventually, both magnetos were removed and run on the bench, when it turned out that the insulation was breaking down at the same time. As a matter of interest, the Rolls-Royce Falcon in the Shuttleworth Bristol Fighter is the oldest Rolls-Royce aero engine still operating anywhere in the world.

As may be surmised from all this, the aircraft has no vices and is very docile and easy aeroplane to fly. Although it has no wheel brakes, the braking action of the tailskid combined with a touchdown speed of 40-45 mph gives a very short landing run. In the air, the elevator is light, the rudder very light and the aileron control increasingly heavy with speed. Because of this lack of control harmonisation and the amount of aileron drag, coordinated turns without slip or skid need practice if one is used to modern aircraft. It must have needed good co-ordination to sight accurately in a dogfight.

1 'Jacko', the late Squadron Leader L. A. Jackson. He was Richard Shuttleworth's first engineer and became Manager of the Collection until he retired in December 1966.
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#25 piecost

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Posted 21 February 2011 - 16:58

Bristol Fighter Radiator & Overheating

Testing of the Time Taken to Boil Coolant Water Away
­
November, 1921 THE AERONAUTICAL JOURNAL page 563
PROCEEDINGS. FIRST MEETING, 57th SESSION.

AEROPLANES IN TROPICAL COUNTRIES.

12. Now as regards the engines. I could not find any trouble specially due to the climate either in Egypt or Mesopotamia. Of course for most machines an additional radiating surface is necessary; for instance, on the D.H.9A the size of the standard radiator is 6.65 sq. ft., and an auxiliary radiator has to be fitted with an area of 2,5 sq. ft.; on the Bristol Fighter the sizes are, main radiator area 4.1 sq,ft., auxiliary radiator 1.54 sq. ft. With these radiators the water can be kept well below boiling even in the middle of the day.

The most important thing, as most people know, is to prevent the water beginning to boil. Once it has started, it is very difficult to stop. On one occasion I made my pilot take off a machine not fitted with extra radiators at 4 p.m. in the middle of the desert. Both the engines started to boil before we got off the ground, and by the time we got into the air we resembled a locomotive. We had to give it up after about ten minutes, and during that time lost 10 gallons of water out of the 16, in the whole system. Making up 10 gallons is rather a serious problem when you are carrying nothing but drinking water, with the next well 120 miles ahead. During some experiments carried out at Martlesham on this subject, it was found that 72 per cent of the total water in the system could be lost in three minutes. It is therefore very important to keep a close eye on one's radiator thermometer in the tropics and not to do foolish things, such as leaving one's radiator shutters closed by mistake.

Fitting an auxiliary radiator is much preferable to merely enlarging the size of the standard radiator, because in the cold weather the radiating surface is too large with the extra radiator, and the latter can then be taken off, thus reducing the head resistance.
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#26 piecost

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Posted 23 February 2011 - 22:18

Flight Test Measurement of Lift & Drag of Bristol Fighter

THE JOURNAL OF THE ROYAL AERONAUTICAL SOCIETY, PROCEEDINGS, ELEVENTH MEETING, [piecost: 1924 IIRC]
THE WORK OF THE AERONAUTICAL RESEARCH COMMITTEE'S PANEL ON SCALE EFFECT

W. S. Farren M.B.E.

[piecost note: Old British Drag Coefficient KD = 0.5 x CD, old British Lift Coefficient KL = 0.5 x CL ]

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#27 piecost

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Posted 23 February 2011 - 22:22

Flight Test & Wind Tunnel Model Drag Polar of Bristol Fighter

THE JOURNAL OF THE ROYAL AERONAUTICAL SOCIETY, PROCEEDINGS, ELEVENTH MEETING, [piecost: 1924 IIRC]
THE WORK OF THE AERONAUTICAL RESEARCH COMMITTEE'S PANEL ON SCALE EFFECT

W. S. Farren M.B.E.

We have finally to make allowance for the main feature in which the model and full scale experiments are not geometrically similar, which is due to the presence of the wind tunnel walls in the model work. I do not propose to enter into a discussion of the Prandtl theory, but you, are aware that it enables us to estimate the effect of the tunnel walls on the characteristics of an aerofoil, and that exhaustive experiments have shown that the correction does bring into agreement tests on the same model in wind funnels of various sizes. The correction has been applied to all the results shown below, and you will be able to judge the extent to which it improves the agreement from Fig. 5, which shows the comparison between one set of full scale experiments and the corresponding model results with and without the correction.

[piecost note: Old British Drag Coefficient KD = 0.5 x CD, old British Lift Coefficient KL = 0.5 x CL ]

[piecost note: curves represent wind tunnel & corrected wind tunnel, dots are flight test measuremens]

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#28 piecost

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Posted 23 February 2011 - 22:32

Flight Tests & Wind Tunnel Lift & Drag Measurements of Bristol Fighter with 3 Sets of Wings

THE JOURNAL OF THE ROYAL AERONAUTICAL SOCIETY, PROCEEDINGS, ELEVENTH MEETING, [piecost: 1924 IIRC]
THE WORK OF THE AERONAUTICAL RESEARCH COMMITTEE'S PANEL ON SCALE EFFECT

W. S. Farren M.B.E.

The first set of results shown in Figs. 6 and 7 are those referred to by Mr. Wood in his paper a year ago as being then incomplete. They were made on a Bristol Fighter aeroplane with wings of three different aspect ratios. You will observe that the agreement on lift is almost complete, including now the maximum lift which has hitherto been rather uncertain. Owing to an improvement which has been made in the full scale method of measuring air speed, and also to the experience which the pilots now have in flying steadily in the neighbourhood of the stall, the accuracy of the full scale determination is considered to be practically as good as at higher speeds.

In drag there is fairly uniform discrepancy. The full scale results agree with the shape of the model curve, but are generally below it by an amount which is considered to be greater than the probable error of the experiments.

[piecost note: Old British Drag Coefficient KD = 0.5 x CD, old British Lift Coefficient KL = 0.5 x CL ]

[piecost note: curves represent wind tunnel, dots are flight test measurements]

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#29 ImPeRaToR

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Posted 10 March 2011 - 09:14

"While the Bristol Fighters could not match the Fokker's speed or agility, they could be formidable opponents, appearing from a distance to be cumbersome, less-manoeuvrable two-seat reconnaissance aeroplanes."

Further: "The Bristol Fighter's 'pilot had the widest possible field of vision … [and his back-seat] observer was was given a wide field of fire' that provided the aeroplane with excellent defensive capabilities."

source: Black Fokker Leader, Peter Kilduff, he quotes Carl Degelow here who he interviewed in 1967.
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#30 piecost

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Posted 18 April 2011 - 15:59

Wind Tunnel Data for Bristol Fighter Wing Section

A.3.a. Aerofoils-general, 69. ADVISORY COMITTEE FOR AERONAUTICS. REPORTS AND MEMORANDA (New Series)~ No. 377.

TESTS ON TWO AEROFOILS FOR THE BRITISH AND COLONIAL AEROPLANE CO., LTD.
By C. H. POWELL, B.8c.

Reports and memoranda (New Series), No. 377. October, 1917.

Summary-Two Bristol wing sections; F2B and Scout E, were tested over the usual range of angles for lift, drag and centre of pressure at a wind speed of 40 ft. /sec.

A comparison is made between the performances of an aeroplane fitted with wings of RAF 16 and the above two sections. Of these three sections, RA F 16 is superior to Scout E, the better of the two sections at low lift coefficients, which correspond to the maximum speed of an aeroplane. For climbing, however, the F.2.B wing section is superior to RA.F 16.

Apart from its aerodynamical properties, RAF 16 takes a deeper front spar but a shallower rear spar than either F2B or Scout E.

These aerofoils are named F.2.B and Scout E. They were made of the usual rectangular shape, 18" span and 3" chord, in brass. After being cut, they were measured up and their dimensions are given in Tables 1 and 2. The profiles are shown in Fig. l.

The tests were carried out at a wind speed of 40 ft./sec. and at angles of incidence, -10°, -8°, - 6°,
-4°, - 3°, -2°, -1°,0°, 1°, 2°, 3°, 4°, 5°, 6°, 8°, 10°, 12°, 14°, 16°, 18°, 20°.

Lift, drag, L/D, normal force, longitudinal force, C.P. and moment about the leading edge are all given in Tables 3 and 4. The angles of incidence for the normal and longitudinal forces are given with reference to the common tangent of the under surface.

The results are also plotted in figs. as below :­

Lift coefficient against angle of incidence__________________________Fig. 2.
Drag coefficient against angle of incidence_________________________Fig.3.
L/D against lift coefficient______________________________________Fig. 4.
L/D against lift coefficient______________________________________Fig. 5.
Centre of pressure against angle of incidence______________________ Fig. 6.
Moment coefficient about the leading edge against angle of incidence___ Fig. 7.

In order to make a fair comparison of these wings wings with.others that have been tested at the National Physical Laboratory, it. is necessary to take into account the depth of the spar which a given wing can take as well as the aerodynamical properties of the wing sections.

Of the two wings under consideration, Scout, E appears to be the better for high speed work, inasmuch as it has a higher L/D at low lift coefficients (0,1, for example) and also a higher
maximum lift coefficient. It will also take a slightly deeper spar, as shown in the following table :­

TABLE.

Scout E front spar depth = 0.067 at 0.14 front leading edge
……………………………..= 0.068 at 0.17 to 0.2 from leading edge.
F.2.B. front spar depth .. = 0.062 at 0.14 to 0.21 from leading edge
R.A.F.15 front spar depth = 0.062 at 0·125 to 0.2 from leading edge
R.A.F.16 front spar depth = 0.070 at 0.125 to 0.2 from leading edge

The dimensions are given above as fractions of the chord.

It will be seen from Fig. 5 that Scout E has a higher maximum lift, and hence a lower stalling speed. and at the same time a higher L/D at 0.1 lift coefficient which may be taken as representing the top speed. If the wing areas be adjusted for equal stalling speeds, then F.2.B appears at. a still greater disadvantage. On the other hand, F.2.B has an appreciably higher value of L/D at. large lift coefficients, i.e., above the maximum L/D, and accordingly an aeroplane will climb more efficiently with F.2.B than with Scout E section.

R.A.F. 16 wing section is plotted for comparison. Apart from its aerodynamical properties, R.A.F. 16 takes a deeper front spar, but has a shallower rear spar than either Scout E or F.2.B.

As far as aerodynamical properties are concerned, R.A.F. 16 is superior to Scout E at a lift coefficient of 0.1, having a value of L/D of 11.2 as compared with 9 for Scout E. If, however, the areas are adjusted, as shown in Fig. 5, to give the same stalling speeds, the L/D ratios are respectively 10.8 and 9.

For equal wing areas F.2.B has a superiority over R.A.F.16 for climbing. But, again, if efficient climb be an important consideration, the wing area for the R.A.F. 16 machine con be increased by, say, 15 per cent., when we shall have the same value of L/D for climb, a reduction of L/D from 11.2 to 9. 7 at 0.1 lift coefficient, which is still higher than F.2.B with an L/D of 7.3 at this lift, and at the same time the stalling or minimum speed is lower.

This comparison, of course, neglects the extra weight of the larger wings and also the increased resistance of the struts and wires.

[piecost note:

The data uses the old British definitions of aerodynamic coefficients:

Lift Coefficient K_L = Lift / ( density x Velocity^2 x Area )
Drag Coefficient K_D = Drag / ( density x Velocity^2 x Area )
Moment Coefficient K_M = Pitching Moment / / ( density x Velocity^2 x chord^2 x span ) (IIRC)

This data was obtained before Reynold's number effects were well understood. The tested Reynold's number was approximatly 60,000. This is well below the number of the full-scale aeroplane of roughtly 6,000,000 (say, for a 6ft chord wing flying at 80 mph at Sea-level ISA). Significant differences between this data and full-scale are to be expected. It is likely that the model tests will:
under predict the lift curve slope
under predict the stall angle & maximum lift
Give different lift & pitching moment characteristics at the stall
Over predict the zero lift drag
Give different pitching moment

So, this data cannot be applied to a full scale F2B without modification. It may be reasonable to compare the data with other wing sections tested in the same National Physical Laboratory at the same conditions. This assumes that the Reynold's number effects are consistent between different aerofoils. A better approach would be to use a computational method such as XFOIL. The tabulated aerofoil geometry enables this.

It is not clear whether the model wing (of 18 inches span and 3 inches chord) extended over the whole width of the wind tunnel to give an "infinite aspect ratio" - hence the data representing (2-dimensional) sectional coefficients.

Or if the model wing was of less span than the tunnel width (or if the tunnel had an open-jet) then the effects of the wing tips becomes important. The data is not representative of a 2D section, but of an aspect ratio=6 wing. Corrections must then be applied to determine the sectional data. I believe this to be the case. ]

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#31 piecost

piecost
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Posted 26 April 2011 - 15:20

Reynolds number effect on Wind tunnel models of Bristol Fighter with RAF15 & RAF30 wings and BE2E with RAF19 wings


NACA report 279

[piecost note: these results show the significant Reynold's number effects on the models tested in the National Physical Laboratory 7ft wind tunnel, The NACA tunnel was pressurized to different levels to vary the Reynold's number]

http://aerade.cranfi...-report-279.pdf" onclick="window.open(this.href);return false;">http://aerade.cranfi...ac.uk/ara/1928/ … rt-279.pdf
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#32 piecost

piecost
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Posted 27 May 2011 - 15:47

The Lift & Drag of a Standard Bristol Fighter Aeroplane

Reports & Memoranda No 897. November 1923

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#33 JimmyBlonde

JimmyBlonde
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Posted 27 May 2011 - 16:04

Yes, one of my fovorite WW1 planes.

Question — does anyone know what the black curved bar is, just above the joystick?

Thanks for posting by the way.

II believe it is there to lock the stick in a central position and avoid having and tension on the control wires.
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#34 piecost

piecost
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Posted 27 May 2011 - 16:09

The Lift & Drag of a Standard Bristol Fighter Aeroplane with RAF4D Engine Comparitive Full Scale & Model Tests

Reports & Memoranda No 896. November 1923

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#35 piecost

piecost
  • Posts: 1318

Posted 27 May 2011 - 16:10

The Lift & Drag of a Standard Bristol Fighter Aeroplane with RAF4D Engine Comparitive Full Scale & Model Tests

Reports & Memoranda No 896. November 1923

…continued

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#36 piecost

piecost
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Posted 27 May 2011 - 16:28

Lift, Drag & Pitching Moment of the 1/5th Scale Bristol Fighter Model in the Duplex Wind Tunnel

Reports & Memoranda No 876. November 1923

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#37 piecost

piecost
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Posted 27 May 2011 - 16:34

Lift, Drag & Pitching Moment of the 1/5th Scale Bristol Fighter Model in the Duplex Wind Tunnel

Reports & Memoranda No 876. November 1923

…continued

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#38 =FB=Chapay

=FB=Chapay
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Posted 28 May 2011 - 15:25



Bristol fighter - buy and healthy - fly!
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#39 piecost

piecost
  • Posts: 1318

Posted 28 May 2011 - 16:34

Fantastic video, however I cannot see the aiming graticule. It nicely shows the rudder movement
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#40 piecost

piecost
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Posted 01 June 2011 - 21:39

Full Scale of a Bristol Fighter with Increased Rudder Control

Reports & Memoranda No. 972

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