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What influences plane's manouverability


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#41 ZachariasX

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Posted 30 March 2016 - 19:45

I read that someone building a replica discovered that the fabric attachment method was flawed, but for historical reasons they used the same method for the replica.
 
 
Yes the RoF N28 could just do with another problem couldn't it?
 

With the ailerons on the lower wing, provided that the upper wing didn't break-up or detach, the main problem facing the pilot should have been a much higher landing speed than normal. Perhaps other pilots didn't appreciate that fact.
I'm wondering whether the responsiveness of the tail group could be compromised by turbulence generated froim the damaged wing.

AFAIK only a minority was able to land safely after such an incident. So it is certainly not trivial to land like that. But that may also reflect the fact that pilots had no training for emergency situations. Even spinning would kill them in flight school. So they were like sailors who can't don't learn to swim. What good is that anyway if you go overboard in the middle of the ocean...

The N.28 as we have it is like as if it was toned down to what an average pilot dared to do as maneuvers without the fear of losing wings. The upside is, our N.28 is also too fast ;)
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#42 =HillBilly=

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Posted 30 March 2016 - 19:57

 

 

 The upside is, our N.28 is also too fast  ;) 

Depends on source, most say 198 kph @ 2,000 meters, store says 177 kph @2,000 meters. If I read the French gauge right says it will go 220 kph, but who knows for sure. ;)  


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#43 ZachariasX

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Posted 30 March 2016 - 20:12

Depends on source, most say 198 kph @ 2,000 meters, store says 177 kph @2,000 meters. If I read the French gauge right says it will go 220 kph, but who knows for sure. ;)


Ok, then it's (maybe) not too fast. But the engine doesen't blow up if blipped > 2 sec. And it sounds funny. That's something.
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#44 =HillBilly=

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Posted 30 March 2016 - 22:04

. And it sounds funny. That's something.

LOL Yes they do. :D This is a Gnome 9n in a Fokker DVIII.


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#45 Ben_Twings

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Posted 31 March 2016 - 02:02

Ben I'm really surprised at this attitude, after all you're the one crying about realism. 

 

I would be happy to accept that weakness in place of its implausible elevator response.


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Polish-infested London


#46 ZachariasX

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Posted 31 March 2016 - 09:05

I would be happy to accept that weakness in place of its implausible elevator response.

 

That is? In your words?


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#47 =HillBilly=

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Posted 31 March 2016 - 13:01

I would be happy to accept that weakness in place of its implausible elevator response.

Implausible elevator response? How is it implausible? Could you please explain, does it over-control, under-control, what?  


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#48 JoeCrow

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Posted 02 April 2016 - 22:18

I think this is a little over simplified.  Thrust must be equal to drag to maintain level flight.  Excess thrust beyond what is required to overcome drag is used to climb.  Drag is dependent upon lift drag and form drag.  Lift drag is dependent upon weight and airspeed and wing shape (AR and airfoil).  This means I can affect the total drag with the wing shape.  If I manage to decrease total drag (with a higher AR for example), then I have more excess thrust for climbing higher/turning. 

 

No, I'm afraid that I don't agree. Thrust must indeed be equal to weight at cruise-speed but it is maximum airspeed that is affected and not cruise-speed. The thrust/weight ratio relative to L/D only affects speeds above cruise speed purely because there is always an excess of thrust over weight at cruise-speed up to absolute ceiling. The rate of fall-off would indeed be different at cruise-speed but not so at maximum-speed (in level-flight) at increasing altitude.

Cheers.


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#49 xvii-Dietrich

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Posted 02 April 2016 - 22:37

I disagree with both.
 

Thrust must be equal to drag to maintain level flight.

 

Thrust and drag are anti-parallel forces. If thrust equals drag, then the net forward force on the plane is zero. That means that the acceleration is zero. (Newton's second law, F=ma).

If thrust is greater than drag, the plane accelerates. But, because drag is usually velocity dependent, this results in a new equilibrium being achieved.

 

Thus, thrust/drag affect the aircraft forward velocity.

 

Thrust must indeed be equal to weight at cruise-speed but it is maximum airspeed that is affected and not cruise-speed. The thrust/weight ratio relative to L/D only affects speeds above cruise speed purely because there is always an excess of thrust over weight at cruise-speed up to absolute ceiling. The rate of fall-off would indeed be different at cruise-speed but not so at maximum-speed (in level-flight) at increasing altitude.

Thrust does not need to equal weight at cruise speed. These are orthogonal forces. They are related by lift, but you can have high-lift, low thrust (e.g. a solar-powered plane) or low-lift, high thrust (e.g. a modern jet fighter) and still maintain level flight. Thrust capability and weight are often coupled (due to the mass of engines), but this is coincidental and is not an outcome of the physical laws describing the motion.


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#50 JoeCrow

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Posted 03 April 2016 - 03:08

I disagree with both.
 

 

Thrust and drag are anti-parallel forces. If thrust equals drag, then the net forward force on the plane is zero. That means that the acceleration is zero. (Newton's second law, F=ma).

If thrust is greater than drag, the plane accelerates. But, because drag is usually velocity dependent, this results in a new equilibrium being achieved.

 

Thus, thrust/drag affect the aircraft forward velocity.

 

Thrust does not need to equal weight at cruise speed. These are orthogonal forces. They are related by lift, but you can have high-lift, low thrust (e.g. a solar-powered plane) or low-lift, high thrust (e.g. a modern jet fighter) and still maintain level flight. Thrust capability and weight are often coupled (due to the mass of engines), but this is coincidental and is not an outcome of the physical laws describing the motion.

That is why I originally said that the lift/drag ratio (as a whole) changes relative to airspeed. The lift/drag and thrust/weight forces are inverse. It is not cruise-speed but maximum level-flight speed (above cruise-speed) that is affected. When usable excess thrust-over-weight falls to zero then you are at your ceiling because of the inverse affect of thrust/weight on the lift/drag ratio (as a whole). Nothing is left at the absolute ceiling because the maximum level-flight speed, minimum level-flight speed and cruise-speed all become equal.  So, consider the effect of adding thrust without increasing weight or the inverse.

 

Of course, if you are comparing two different aircraft you will obviously get two vastly different results but the aerodynamic cube-law rule still applies to both.

 

Don't forget that drag also rises in proportion to lift and the lift/drag ratio (as a whole) rises and falls in proportion to airspeed, which takes us right back to the thrust/weight ratio.

 

Cheers.


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#51 Chill31

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Posted 12 April 2016 - 17:24

No, I'm afraid that I don't agree. Thrust must indeed be equal to weight at cruise-speed but it is maximum airspeed that is affected and not cruise-speed. The thrust/weight ratio relative to L/D only affects speeds above cruise speed purely because there is always an excess of thrust over weight at cruise-speed up to absolute ceiling. The rate of fall-off would indeed be different at cruise-speed but not so at maximum-speed (in level-flight) at increasing altitude.

Cheers.

 

Erm...So if my plane weighs 1000 lbs, I need 1000 lbs of thrust?  Nope!  I need 1000 lbs of lift.  I need only enough thrust to overcome drag and maintain a speed that produces 1000 lbs of lift.  Yes, thrust and weight are related in the overall performance of the plane, but not in the exact way that you are describing.  https://www.grc.nasa...ane/forces.html


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#52 Chill31

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Posted 12 April 2016 - 17:34

I disagree with both.
 

 

Thrust and drag are anti-parallel forces. If thrust equals drag, then the net forward force on the plane is zero. That means that the acceleration is zero. (Newton's second law, F=ma).

If thrust is greater than drag, the plane accelerates. But, because drag is usually velocity dependent, this results in a new equilibrium being achieved.

 

Dunno why you disagree with what I said...it is 100% accurate.  If thrust > drag, the plane accelerates, generates more lift, and without a change in flight controls, will pitch up (excluding supersonic aerodynamics), climb, and slowdown.  If thrust < drag, the plane decelerates, lift decreases, pitches down, and the plane accelerates by force of gravity.  If you're referring to the ability to change control forces and maintain level flight while changing airspeed, then yeah ok, you got me. 


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