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The Fokker DVII


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#1 Panthera

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Posted 05 January 2012 - 19:37

Hello fellow pilots :)

I'd like to talk a little about the Fokker DVII and its' flying characteristics ingame.

In my experience the ingame Fokker DVII has trouble turning with some of the other fighters ingame, namely the Sopwith Camel.

Now according to what I've read and been told it was the other way round in reality, the Fokker DVII being one of the most maneuverable fighters of the great war, and also considered the best fighter of the war by most experts thanks to its excellent blend of agility & performance.

Anyway the key to the Fokker DVII's success apparently lay in its' wing design which used a much thicker and different profile airfoil than the other aircraft of the time.

Now when most of us amateurs try to figure out how well an aircraft turns we simply divide the weight of the aircraft with it's available wing area. However this is apparently a very dumbed down and inaccurate method to use, and at best it only tells half the story, as one wing can be much more efficient at creating lift pr. given area than another one.

Now this efficiency at creating lift is normally expressed as the wings 'coefficient of lift' or "CL", and the higher it is the more lift the wing generates pr. area. And this is where the Fokker DVII supposedly had a big advantage, its' wing generating a very high lift coefficient compared to wings of all other aircraft.

Anyway I wonder if the Fokker DVII's higher efficiency at creating lift has been taking into account when making its' flight model for this game?

Cheers! :S!:
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#2 gavagai

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Posted 05 January 2012 - 19:48

Yes, it has Panthera. Our D.VII is something of an oddity because of the three engines used in the D.VII, ours has the weakest and least common type.

Most D.VII's had an overcompressed D.IIIau Mercedes engine, but there is no reliable test data for this configuration. German data was likely destroyed in WW2, and the Allies didn't know to add Benzol to the fuel, so the results of their tests were unimpressive and did not correspond to the aircraft's actual performance.
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#3 Panthera

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Posted 05 January 2012 - 21:38

Now I just realized that there's another version available for purchase, the DVIIF which has the 230 hp BMW engine. Perhaps this one hangs around the turns abit better?

Anyway, turn performance wise the Fokker DVII was one of the best of the war, and I'm wondering if this is reflected in this game as-well ?

Reason for me wondering this was my inability to outturn a Sopwith Camel at one point online, something I believe the DVII quite readily was capable of in real life thanks to its, at the time, very advanced wing design.
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#4 WhoCares

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Posted 05 January 2012 - 21:52

The DVIIF is the best "Jack-of-all-traits", very maneuverable and also one of the fastest (depending on the altitude), easy to handle, good visibility, …
However, if you expect to outturn a Camel, the most maneuverable Entente plane, or outrun a Spad or Se5a on the deck, you will be up for a bad surprise.
In fact, on the deck you will even have a problem with running from a Camel (in its current state) :xx:
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#5 hq_Jorri

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Posted 05 January 2012 - 23:48

The D.VII (any version) was never exceptional in any area, but it was built to be an all-rounded that was friendly to fly and could be handled well by any pilot, even those with less experience.

So it has a nice top speed, a nice climbrate, an average rollrate and an OK turnrate. But in every area, there will be a plane that exceeds it.

In WWI, that didn't matter as much. Especially in 1918, German aces were getting scarce and there were more and more pilots with little experience on the scene. The fact that the D.VII was easy to fly and fight in, proved to be its primary quality.

It was just a good, solid plane.

Then, at the armistice, it was lifted to a mythical status because it's the only weapon that was named in the armistice treaty, and every example of it was to be handed over to the allied forces.

Now, it might have been a good plane but it's not like they wanted to equip their own airforces with the D.VII after the war. So why this demand?

Its good overall performance certainly had something to do with it. But equally as important, were the fact that it used some extraordinary design features.

The Fokker D.VII had a welded steel fuselage. The wings were of a very thick profile, and were strong enough to not require any bracing. The engine bay was built in such a way, that it was very easy to exchange the Mercedes or BMW engine for another without having to significantly rework the frame.

So the 'captured' D.VII's were sent to the victors, mostly to America, where they were received by aircraft manufacturers to be studied and copied in their own designs.

This was not as much due to its performance, as it was due to its design.

And so, the Fokker D.VII became the father of many aircraft designs in the interbellum. Just compare the struts on the Stearman to the D.VII, for example. The steel N-shaped struts were a typical Fokker design feature.

So all of the above is the reason behind the Fokker D.VII's fame.

Unforunately, none of this involves outturning a Sopwith Camel at ground level with 20% fuel.
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#6 J2_Adam

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Posted 06 January 2012 - 07:10

The D.VII (any version) was never exceptional in any area, but it was built to be an all-rounded that was friendly to fly and could be handled well by any pilot, even those with less experience.

So it has a nice top speed, a nice climbrate, an average rollrate and an OK turnrate. But in every area, there will be a plane that exceeds it.

In WWI, that didn't matter as much. Especially in 1918, German aces were getting scarce and there were more and more pilots with little experience on the scene. The fact that the D.VII was easy to fly and fight in, proved to be its primary quality.

It was just a good, solid plane.

Then, at the armistice, it was lifted to a mythical status because it's the only weapon that was named in the armistice treaty, and every example of it was to be handed over to the allied forces.

Now, it might have been a good plane but it's not like they wanted to equip their own airforces with the D.VII after the war. So why this demand?

Its good overall performance certainly had something to do with it. But equally as important, were the fact that it used some extraordinary design features.

The Fokker D.VII had a welded steel fuselage. The wings were of a very thick profile, and were strong enough to not require any bracing. The engine bay was built in such a way, that it was very easy to exchange the Mercedes or BMW engine for another without having to significantly rework the frame.

So the 'captured' D.VII's were sent to the victors, mostly to America, where they were received by aircraft manufacturers to be studied and copied in their own designs.

This was not as much due to its performance, as it was due to its design.

And so, the Fokker D.VII became the father of many aircraft designs in the interbellum. Just compare the struts on the Stearman to the D.VII, for example. The steel N-shaped struts were a typical Fokker design feature.

So all of the above is the reason behind the Fokker D.VII's fame.

Unforunately, none of this involves outturning a Sopwith Camel at ground level with 20% fuel.

Nicely told, Jorri.
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#7 Panthera

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Posted 06 January 2012 - 07:36

The D.VII (any version) was never exceptional in any area, but it was built to be an all-rounded that was friendly to fly and could be handled well by any pilot, even those with less experience.

So it has a nice top speed, a nice climbrate, an average rollrate and an OK turnrate. But in every area, there will be a plane that exceeds it.

In WWI, that didn't matter as much. Especially in 1918, German aces were getting scarce and there were more and more pilots with little experience on the scene. The fact that the D.VII was easy to fly and fight in, proved to be its primary quality.

It was just a good, solid plane.

Then, at the armistice, it was lifted to a mythical status because it's the only weapon that was named in the armistice treaty, and every example of it was to be handed over to the allied forces.

Now, it might have been a good plane but it's not like they wanted to equip their own airforces with the D.VII after the war. So why this demand?

Its good overall performance certainly had something to do with it. But equally as important, were the fact that it used some extraordinary design features.

The Fokker D.VII had a welded steel fuselage. The wings were of a very thick profile, and were strong enough to not require any bracing. The engine bay was built in such a way, that it was very easy to exchange the Mercedes or BMW engine for another without having to significantly rework the frame.

So the 'captured' D.VII's were sent to the victors, mostly to America, where they were received by aircraft manufacturers to be studied and copied in their own designs.

This was not as much due to its performance, as it was due to its design.

And so, the Fokker D.VII became the father of many aircraft designs in the interbellum. Just compare the struts on the Stearman to the D.VII, for example. The steel N-shaped struts were a typical Fokker design feature.

So all of the above is the reason behind the Fokker D.VII's fame.

Unforunately, none of this involves outturning a Sopwith Camel at ground level with 20% fuel.

I have to disagree with your theory of how things were hq_Jorri as this is not what is told by the experts and the people who flew the Fokker DVII, according to them it was so much sought after because of its performance and maneuverability where it excelled over the allied fighters.

Now you say a Camel turns tighter, but I find that hard to believe considering how thin its' wings are. The DVII's wings were sure to produce a whole lot more lift pr. area than the Camel's, and as such the difference in turning performance doesn't just come down to which aircraft has the lowest wing loading.

Infact it wouldn't suprise me if the Fokker DVII has a 30-40% advantage in the amount of lift created by its' wings, in which case it should outturn a Sopwith Camel. Furthermore the 230 HP engine will allow it to keep its turn for longer, or power through a turn where most other fighters would stall out.

Anyway it would be nice to get some actual specifications on the table, such as the CLmax of each aircraft's wings etc etc.. and the available thrust.
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#8 Finkeren

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Posted 06 January 2012 - 08:46

Panthera: I'd like to see your scources for the D.VII outturning the Camel. I've never heard this anywhere. Lift and wing loading are not the only factors determining a planes turn rate. The Camels exceptional maneuverability and unbeatable turnrate in the horizontal plane is largely due to its inherent instability and the gyroscopic force of its rotary engine. That together with its very compact weight distribution, huge control surfaces and low overall weight (with 50% fuel load it's a full 250kg lighter than the D.VII) makes it an extremely nimble aircraft rivaled only by the Dr.1.

It just so happens that in RoF the D.VIIF is quite possible the best CP plane to fight the Camel (together with the Dr.1, if you can handle it) but not because the D.VIIF outturns the Camel! The reason it was so sought after was just as Jorri said because of its ease of piloting (which is supremely important in a real life war, where you can't learn by trial and error) and simply because it outshined everything the else the Luftstreitskräfte had at the time, even if the Entente had planes that were better in some aspects.

Overall I agree with Jorri, the D.VIIF is the perfect jack-of-all-trades (more like a queen-of-all-trades actualy) in RoF, but it is not superior to all other aircraft in any one aspect.

EDIT: Somehow I forgot some of the D.VIIFs biggest assets: It's a great diver and virtually never overrev's, and it has an awesome combination of great acceleration with good ability to hang by its prop and is able to retain energy very well in tight manuvers, it's really the best of two worlds.
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#9 Flashy

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Posted 06 January 2012 - 09:03

Panthera, there are already plenty of threads on FM discussion (especially of the Camel), so you should also read through all of those because your questions regarding wing loading and CLmax etc will probably already have been answered in there.

But with regards to this thread, the Camel was widely regarded as the most maneuverable aircraft of the war (with the possible exception of the Dr. 1), and could turn tighter to the right than just about anything. I'm not sure which sources you have which say that a DVII could outturn a Camel in a pure turn fight (maybe you could post them here?) but I have never come across any reference to the DVII being a better low-altitude turn fighter than a Camel or Dr.1.

What it boils down to is that you have to clarify what you mean by words like "performance" and "maneuverability". At what altitude for example? At high alt, the DVII would perform a lot better than a Camel due to the amount of power the Camel's rotary engine would lose at that alt. Also, the tactics of the war had changed quite a lot by the time the DVII came into service. Pure turn fighters were outdated and high-alt BnZ fighters were the order of the day. That is why the SPAD's and SE5a's and DVII's were favoured (and replaced) planes like the N17, Camel and Dr.1 - they could get up high and dictate the terms of the fight and disengage at will - far more important to pilots than trying to out-turn each other like madmen. In this respect then, the DVII did outperform the Camel because it had the advantage in Bnz and high-alt combat, but that does not imply that the DVII was superior (or even equal!) to the Camel in a low-alt turn fight!
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Just because I can give multiple orgasms to the furniture just by sitting on it, doesn't mean that I'm not sick of this damn war: the blood, the noise, the endless poetry...


#10 hq_Jorri

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Posted 06 January 2012 - 09:13

Another quality of the D.VII, which also comes from the welded steel fuselage and braceless wires, is that it's relatively cheap to manufactuer and cheap and easy to maintain.

That's also a reason why Fokkers are popular with replica builders :)
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#11 Panthera

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Posted 06 January 2012 - 09:26

I tried searching the forums for answers to the question of wing CLmax etc for these two aircraft but found nothing.

As for the Camel's high maneuverability and inherent instability: Whilst for sure the gyroscopic effect of the rotary engine caused this, one must also understand that this will only help you roll quicker in one direction, it won't make your airplane turn tighter circles.

To turn tight circles you need to have the lift needed to do so, and the more lift you have pr. amount of weight, the tighter circles you will be able to turn.

Now I do not doubt that thanks to its inherent instability the Camel was extremely difficult to outmaneuver in certain types of flight, seeing as how quick it would be able to roll to one direction. But in a pure turning contest the much higher lift generated by the DVII's thicker wings, coupled with the much lower power-loading, should allow it to pull tighter turns for longer than the Camel. I feel it's the exact opposite ingame, where the Camel even seems to be able to run along with the DVII in level flight on the deck - quite odd for an aircraft with 100+ less hp which by the time of the DVII's introduction was considered awfully slow and outdated.

Anyway I'd love to see a scientific comparison between these two aircraft if anyone could provide it, even if by means of a link or book reference :)

Thanks :)
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#12 Finkeren

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Posted 06 January 2012 - 09:37

Ok your last post evened out you brash statements. You are indeed touching upon something important here, but it has nothing to do with the D.VII.

The Clerget-engined Camel we have in RoF is indeed too fast and it's gyroscopic effect is much much too weak and hence it's far too easy to handle. Try out the Nieuport 17 for a taste of how the gyroscopic effect should feel (it's overdone in the Dr.1) However, even when these things are fixed in a future FM-review, the Camel will still outturn the D.VII by a large margin.

About the wings: Even if the wing design of the D.VII is superior the Camel still has a significant advantage in wing loading, especially with a half-empty fuel tank.
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#13 Panthera

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Posted 06 January 2012 - 09:45

About the wings: Even if the wing design of the D.VII is superior the Camel still has a significant advantage in wing loading, especially with a half-empty fuel tank.

I still do not understand why this would be the case however, cause the DVII's wing will as mentioned be producing a whole lot more lift, and the lower powerloading should allow it to maintain its turn for longer - infact even climb in a tight turn where the Camel will be unable to follow.

Also why would we compare two aircraft in a manner where one has a full tank and the other a half full one? With both airplanes running on half full tanks the difference would likely be the same between both aircraft as when both are flying on full tanks.
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#14 Finkeren

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Posted 06 January 2012 - 09:56

I still do not understand why this would be the case however, cause the DVII's wing will as mentioned be producing a whole lot more lift,

True, but due to its lower weight, the Camel still has a wing loading advantage of close to 30%, and I highly doubt that the Fokker wing design was that much better.

…and the lower powerloading should allow it to maintain its turn for longer - infact even climb in a tight turn where the Camel will be unable to follow.

At lower altitudes only the D.VIIF has a significant powerloading advantage over the Camel, the normal D.VII doesn't, and you can feel it. The D.VIIF however has exceptionally good energy retention in a sustained turn, as good as the Camel. The Camel just turns tighter. Indeed the D.VIIF can easily beat the Camel in a chandelle. I do it online quite often.

Also why would we compare two aircraft in a manner where one has a full tank and the other a half full one? With both airplanes running on half full tanks the difference would likely be the same between both aircraft as when both are flying on full tanks.

Because 1. The D.VIIs were operating almost exclusively over German territory, while the Camels that engaged them would often be on long offensive patrols. 2. The Camel has an extremely large fuel tank (almost twice the size of the D.VIIs) and a rotary engine with a much worse fuel economy and thus burns off a lot more fuel (and thus more weight)in a shorter time
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#15 Kwiatek

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Posted 06 January 2012 - 10:12

As Finkeren said but also important is that more thick wings casue much more drag at higher angle of attack which to counter is needed a lot of more power.

Thicker wings in Fokker DVII cause that these plane could make really sharp turns which im sure Camel cant follow beacuse it would stall. Many times flying online Camel against DVII i cant follow for a while DVII in sharp turns beacuse i fell then my wings were in stall.
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#16 Finkeren

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Posted 06 January 2012 - 10:15

As Finkeren said but also important is that more thick wings casue much more drag at higher angle of attack which to counter is needed a lot of more power.

Thicker wings in Fokker DVII cause that these plane could make really sharp turns which im sure Camel cant follow beacuse it would stall. Many times flying online Camel against DVII i cant follow for a while DVII in sharp turns beacuse i fell then my wings were in stall.

Good point Kwiatek. The D.VIIF can pretty much be yanked hard in any direction without spassing out. Try the same thing in a Camel and you'll spend the next 10 sec and 1000ft pulling out of the spin.
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#17 hq_Jorri

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Posted 06 January 2012 - 10:18

At the same time, fights in ROF happen quite low, where the Camel is at an advantage. The Camel in ROF is quite overpowered. And the Fokker D.VII in ROF does not have the correct engine.

So if we take that into account, I don't think there is anything wrong with the flight model of the D.VII in ROF and only the above prevents it from fully living up to its name.
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#18 Finkeren

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Posted 06 January 2012 - 10:30

As Gavagai said in the 3rd post: It's not fair to compare the D.VII to anything, because it's modelled with a weak engine compared to the majority of real life D.VIIs. The D.VIIF is a much better indication of why the D.VII was loved by its pilots.
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#19 Tom-Cundall

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Posted 06 January 2012 - 10:35

Sopwith Camel pilots definitely didn't enjoy tangling with the Fokker 'Biplanes' I think in a similar way to the SE5a for the RFC/RAF it had the ability to make an average pilot appear competent/good and a good pilot into a terror - that is the sign of a good plane. The D.VII was certainly the 'ace maker' of the Germans.

Flights of Camels didn't relish combat with them - even on even terms. Unlike the Albs (and to some extent the Fokker Triplane) which if they could be enticed to fight they had a good chance against.
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#20 Finkeren

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Posted 06 January 2012 - 10:43

…it had the ability to make an average pilot appear competent/good and a good pilot into a terror - that is the sign of a good plane. The D.VII was certainly the 'ace maker' of the Germans.

That's certainly true on the NEWBIE-server. I've watched newcomers rank up K/D-scores into 2-didget numbers when flying the D.VIIF.
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#21 MattM

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Posted 06 January 2012 - 10:56

True, but due to its lower weight, the Camel still has a wing loading advantage of close to 30%, and I highly doubt that the Fokker wing design was that much better.
Litloading advantage is closer to half that much though.

But yes, D.VII with uncommon (not "wrong") engine + Camel performing better than it should (and being heavier with full fuel load), just makes it useless to compare those two planes in ROF.

The normal D.VII in ROF is a lame duck. Can probably stand in for a D.Va, but that's pretty much it.
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#22 Panthera

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Posted 06 January 2012 - 12:16

True, but due to its lower weight, the Camel still has a wing loading advantage of close to 30%, and I highly doubt that the Fokker wing design was that much better.

Well looking at the difference in shape & thickness it looks like the difference could be as much as +50%.

Also if I remember correctly the DVII's airfoil high resembles the NACA 23XXX series, which is known for its' high average max lift coefficient between 1.50 to 1.65.

By comparison airfoils of the same thickness and shape as that used on the Camel usually have a average max lift coefficient ranging from between 1.01 to 1.12 or lower.

At lower altitudes only the D.VIIF has a significant powerloading advantage over the Camel, the normal D.VII doesn't, and you can feel it. The D.VIIF however has exceptionally good energy retention in a sustained turn, as good as the Camel. The Camel just turns tighter. Indeed the D.VIIF can easily beat the Camel in a chandelle. I do it online quite often.

Now ofcourse I am only comparing the BMW engined DVII with the Camel here, but even so I cannot make a blanket statement as to exactly how big the real difference is in terms of thrust, as I don't know the actual effectiveness of each aircraft's propeller. However considering the DVII is a later designed aircraft I think it is safe to assume that it's propeller was either as or more effective than that of the Camel. (In my comparison below I will just assume they are the same)

Anyway based on the observations I have made so far from looking at expert opinions, pilot accounts as-well as basic performance and aerodynamic properties I have so far (important to stress 'so far' as I am by no means 100% sure) come to following conclusion in terms of each aircraft's properties:


Fokker DVII (BMW):
Loaded weight: 850 kg
Wing area: 20.2 m²
Engine: 232 hp (250 hp isn't included ingame I presume?)

Predicted CLmax: ~1.55

Power-loading: 0.27 hp/kg
Wing-loading: 42 kg/m²
Relative wing-loading after considering CLmax: 27.1 kg/m²

Predicted top speed: 200-205 km/h

Preticted stall speed: 75 km/h

Sopwith Camel:
Loaded weight: 660 kg
Wing area: 21.46 m²
Engine: 130 hp

Predicted CLmax: ~1.01

Power-loading: 0.19 hp/kg
Wing-loading: 30.7 kg/m²
Relative wing-loading after considering CLmax: 30.4 kg/m²

Predicted top speed: 180-185 km/h

Predicted stall speed: 77 km/h

Now ofcourse this comparison is open to critique and debate, seeing as no doubt a lot assumptions are being made, and ofcourse I welcome any additional insight on each aircraft.
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#23 Nixou

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Posted 06 January 2012 - 12:23

Hello fellow pilots :)
In my experience the ingame Fokker DVII has trouble turning with some of the other fighters ingame, namely the Sopwith Camel.

Now according to what I've read and been told it was the other way round in reality,


Reason for me wondering this was my inability to outturn a Sopwith Camel at one point online, something I believe the DVII quite readily was capable of in real life.
I have to disagree with your theory of how things were hq_Jorri as this is not what is told by the experts and the people who flew the Fokker DVII


Can i have your sources for such subjective and hardly believable statements please?

I have three encyclopedias about WW1 and online data, i have never ever read anywhere that a Fokker DVII outturned the Camel. :)
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#24 ImPeRaToR

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Posted 06 January 2012 - 13:19

The D.VIIF might indeed outturn the Camel if both met with full fuel, but that's hardly going to happen either IRL or in-game.
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#25 rolikiraly

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Posted 06 January 2012 - 14:55

Panthera: I'd like to see your scources for the D.VII outturning the Camel. I've never heard this anywhere. Lift and wing loading are not the only factors determining a planes turn rate. The Camels exceptional maneuverability and unbeatable turnrate in the horizontal plane is largely due to its inherent instability and the gyroscopic force of its rotary engine. That together with its very compact weight distribution, huge control surfaces and low overall weight (with 50% fuel load it's a full 250kg lighter than the D.VII) makes it an extremely nimble aircraft rivaled only by the Dr.1.

It just so happens that in RoF the D.VIIF is quite possible the best CP plane to fight the Camel (together with the Dr.1, if you can handle it) but not because the D.VIIF outturns the Camel! The reason it was so sought after was just as Jorri said because of its ease of piloting (which is supremely important in a real life war, where you can't learn by trial and error) and simply because it outshined everything the else the Luftstreitskräfte had at the time, even if the Entente had planes that were better in some aspects.

Overall I agree with Jorri, the D.VIIF is the perfect jack-of-all-trades (more like a queen-of-all-trades actualy) in RoF, but it is not superior to all other aircraft in any one aspect.

EDIT: Somehow I forgot some of the D.VIIFs biggest assets: It's a great diver and virtually never overrev's, and it has an awesome combination of great acceleration with good ability to hang by its prop and is able to retain energy very well in tight manuvers, it's really the best of two worlds.

I also think that the d.vii was less likely to have structural (wing) damage cause of its steel structure (even if it cant be the main reason why they appreciated it so much)
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#26 neuro

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Posted 06 January 2012 - 15:15

I'm an average pilot and not exactly a Camel expert, and I had some problems fighting a D7 on the deck.
The point being, a D7 with a good pilot in it may be more than a match for a Camel with an average pilot in it.
On the other hand, we have a whole bunch of Camel-dedicated pilots in this game, they fly nothing but the Camel and mostly with less than 25% fuel. Those guys are very hard to fight even by a good pilot in a Dr1…
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#27 gavagai

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Posted 06 January 2012 - 16:02

Now ofcourse this comparison is open to critique and debate, seeing as no doubt a lot assumptions are being made, and ofcourse I welcome any additional insight on each aircraft.

Production Camels with a license-built 130hp Clerget engine were not as fast as the prototype figures we usually see. 180kmh was around the maximum TAS in level flight, @sea level.

Level airspeed figures for the Fokker Dr.1 are similarly overblown, as quoted figures frequently come from the manufacturer's specification.

It's the same thing as when the car manufacturer says 40mpg. You'll be lucky to get 35. ;)

———————

These fit better here:

Image

Image
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#28 Chill31

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Posted 06 January 2012 - 17:53

The D7F in ROF will out fight the Camel above 2500m where the Camel struggles to keep fighting energy.

At 100% fuel, the D7 (not D7F) is at a 36% disadvantage in wingloading. At ALL fuel loads less than 100%, the Camel gets a greater advantage in wingloading maxing at 51% advantage with 10% fuel in both planes.

1.01 for the Camel CLmax…if anyone has the wing profile, let me know. It just sounds low to me without knowing the airfoil.

1.5 for the D7 also seems rather high. The 23000 series refers only to designed lift coefficient and percent chord for max camber…so you could have a very thin 23000 series airfoil and still have low CLmax…again without the D7 airfoils on hand, 1.3-1.4 would probably be appropriate.
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#29 Armincles

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Posted 06 January 2012 - 18:04

The D.VIIF might indeed outturn the Camel if both met with full fuel, but that's hardly going to happen either IRL or in-game.

Thats why fuel lock sucks!
;)
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#30 Panthera

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Posted 06 January 2012 - 18:18

1.01 for the Camel CLmax…if anyone has the wing profile, let me know. It just sounds low to me without knowing the airfoil.

1.5 for the D7 also seems rather high. The 23000 series refers only to designed lift coefficient and percent chord for max camber…so you could have a very thin 23000 series airfoil and still have low CLmax…again without the D7 airfoils on hand, 1.3-1.4 would probably be appropriate.

The NACA 23XXX series varies between 1.50 to 1.65 in CLmax in the thickness ratios of 12 to 18%, and the DVII's wing looks to be within that range of thickness.

The Camel's wing on the other hand looks unusually thin, with a thickness ratio somewhere between a 5-7%. With that in mind I can definitely see why it had such sharp stalling characteristics.

In short I believe that the Fokker DVII's wing possessed a CLmax roughly 50% higher than that of the Camel's wing, and that coupled with the DVII's much lower power-loading should enable it to turn tighter than the Camel.
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#31 Chill31

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Posted 06 January 2012 - 23:02

Where are you getting the CLs from? I would like to have a nice new data source myself

I've been using JavaFoil to approximate CLs. http://www.mh-aeroto...ls/javafoil.htm" onclick="window.open(this.href);return false;">http://www.mh-aeroto...ls/javafoil.htm
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#32 Panthera

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Posted 07 January 2012 - 01:02

Where are you getting the CLs from? I would like to have a nice new data source myself

I've been using JavaFoil to approximate CLs. http://www.mh-aeroto...ls/javafoil.htm" onclick="window.open(this.href);return false;">http://www.mh-aeroto...ls/javafoil.htm

Check out NACA's Technical Reports, they're loaded with CL figures for the different airfoils :)

Here's the figures for the NACA 23XXX series:
Image

This chart also shows Cl figures from 6 to 21% thickness ratio, the DVII's airfoils were somewhere in between 9-14% in thickness as far as I can tell.
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#33 Chill31

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Posted 07 January 2012 - 05:53

Ok, after some digging…reference: http://ntrs.nasa.gov..._1993091108.pdf" onclick="window.open(this.href);return false;">http://ntrs.nasa.gov/archive/nasa/casi. … 091108.pdf

this document doesnt have the actual Camel and D7 airfoils in it, BUT you will quickly see the effects of 1) camber and 2)thickness on CL, CD, and subsequently L/D. I like this document because its from 1933 and they do include reynolds number in the wind tunnel test. I didnt go back to check their numbers with the assumption that they knew what they were doing…hopefully that is the case.

So for the Camel. If we take the same thickness of wing, and increase the camber by just 2 percent of the chord length (leading edge to trailing edge) the CLmax goes from 1.05ish to 1.2ish. If we increase the thickness by just 3% of chord length(without changing camber) then the CLmax goes from 1.05ish to 1.5ish. So you can see how sensitive an airfoil can be to small changes in its shape.

If we say the D7 has a wing very similar to the NACA 6315, then we would expect a CLmax of about 1.5. Looking at the Camel wing, it has a shape most similar to the NACA 4306 which has a CLmax of about 1.2.

At the "Camels" CLmax, the "D7" would have the same L/D (energy retention based solely on airfoil). So this means that in a steady state turn, the D7 and Camel would have about the same sustained turn capability, (though not the same turn rate).

The Camels CLmax is about 1.2. If the D7 tries to match energy retention (have the same L/D) it will also have a CL of about 1.3. With the Camel having a wing loading about 30-50% less than the D7, you can see he is devoting more of his lift to turning, and thus should have a higher turn rate.

Could the D7 cash it all in and try to get a shot off? sure, but he's going to be losing airspeed and with it lift which is essential to his turning ability.

**some caveats, you can see how sensitive the CLs are to airfoil shape and I did NOT use actual Camel and D7 airfoils. Only what looks the closest in the available data in my opinion. Also, this "analysis" is based solely on a specific airfoil section. The D7 has a tapered wing and two different wings on each plane, not to mention airframe drag. So there is room for error! But I think there is enough data to show that the Camel has the potential to out turn the D7 even with CL disparity. I hope that answers the OPs post.
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#34 Panthera

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Posted 08 January 2012 - 20:13

Hi Chill,

As far as I can see the airfoil that resembles the DVII's the most in there is the NACA 6412 (12%), which has a CLmax of 1.68, where'as the airfoil which resembles the Camel's the most would be the NACA 2406 (6%) which has a CLmax of 1.05.

Also keep in mind that the Camel's airfoil has a sharp leading edge, and this is something that will reduce the CLmax whilst at the same time reduce drag. This sharp leading edge will no doubt also be a leading culprit in the nasty and sudden stall characteristics of the Camel.

By comparison the DVII's airfoil has a very wide and round leading edge and about the same camber, making for a very high CLmax. On top of this the DVII's airfoil is twice as thick as the Camel's, and the thicker the wing the more air is displaced = the more lift you produce.

Here's the Camel's airfoil profile:
Image
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#35 Panthera

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Posted 08 January 2012 - 20:16

A comparison between the airfoils used [Top to bottom: SPAD 13, Sopwith Camel, Albatros DIII, Fokker DVII):
Image

As you can probably already extrapolate from the illustration above the Fokker DVII's airfoil was no doubt a giant leap forward in terms of lift production, outperforming the rest in CLmax by between 0.5 to 0.8 with an average CLmax of between 1.55 to 1.65.
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#36 winger2

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Posted 08 January 2012 - 20:24

A comparison between the airfoils used [Top to bottom: SPAD 13, Sopwith Camel, Albatros DIII, Fokker DVII):
Image

As you can probably already extrapolate by just looking at this the Fokker DVII's airfoil was a giant leap forward in terms of lift production, outperforming the rest in CLmax by between 0.5 to 0.8.

Very interested in seeing where this will lead. My stomach tells me nowhere since the windmills youre fighting here are always stronger:P
I wish you the best of luck!

Winger
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#37 Kwiatek

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Posted 08 January 2012 - 22:31

Image
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#38 Panthera

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Posted 09 January 2012 - 00:52

That's a nice chart showing the drag of the airframe Kwiatek, thanks for that :)
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#39 Finkeren

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Posted 09 January 2012 - 13:28

It's nice to see a thread that started out as something of a flame war (for which I was partly responsible) evolving into a serious discussion based on facts. We are already past the point where my knowledge of aerodynamics falls short, but I'm very interested in the results. :)
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#40 242Sqn_Wolf

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Posted 09 January 2012 - 13:32

Image

That is a nice chart kind interested where you found it?
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