I read an article on the B26 where a former pilot just after the war in the Pacific was flying a new A26 Invader and he said he pulled up next to a Navy fighter plane, shut down the engine on that side, waved to the Navy fighter pilot and proceeded to outrun him on one engine. It did not state what fighter the Navy pilot was in, but I figured it had to be an FM2. Don't know if it is true or not.
Ta152H questions
- Thread starter Milosh
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Hello Milosh
This fact is logical and mentionned by JY Lorant works, a more than enough qualified and well known specialist over the FW family, i hope.
Everybody that went in school can remember (or should remember) the ice skater problem, that turning faster on itself when arms are closer to the body.
I never saw precise numbers, but we can try a "scientifical" approach.
First, and foremost in our case (dogfight) the roll rate is not such an important as the angular acceleration, and control respunse. I would say it's 100 times more important to launch an immediate roll and stop or invert it at only 60°/s such immedialtly, than reach 240°/s roll rate at "not before" the 26-27th full barell, with 9°s per 360° acceleration-deccelaration increase rate. This is just an example, showing that "max roll" alone without any roll (radial) acceleration is useless.
This is the inertia moment problem, proporionnal to M. L². Since the new wing will be heavier and 14.8/10.51 bigger this would affect (increase) resistance to movement at quadratic law (x^4) at least. So (1.4)² for L, no problem it's in the formula, 1.4² also for wing weight M, considering with simplification that wing structure density (kg/m²) would to be kept at same dimension. Well I have intentionnaly negligated the fact that "all proportions kept" a 1.4 bigger wing should have 1.4² more aera and 1.4^3 more weight, by leazyness, but it's rather a conceptual than physical problem. Moreover the high aspect ratio new wing would be affected by a serious adverse yaw, that should have been much lighter on previous short wing variant. (Ask to glider's pilots).
So before considering any rate of roll problem, the plane (Ta -152) with the new bigger wing would have very long and sluggish reaction to the control column, and very poor radial acceleration compared to the "normal" Dora.
Now, considering the established roll rate in itself, it has little relationships with the inertia moments. See high roll rate of the P-38 and french Corsair with assisted ailerons. But the time for them to use this astonishing roll, a lot of things could be done against them in the meanwhile with Yak-11s, P-40's and even A 6 Texans at la Ferté Alais Warbirds collection base.
The roll rate is depending on a lot of factors, such as wing shape, aileron design, wing rigidity, and mobile to fixed aera ratio...
In that case the champion in all warbirds category should have been the 1934's Polikarpov I-16 tip 4 with 360°/ in 1-1,2s. For "modern" fighters probably the La-7 with 9.8% mobile aeras (less than 6% for the 109).
Otherways: my proposal is to modellise the whole plane as a two bladed wind turbine with very low output. Applying Betz forulas, all that we see is that power absorbed by the passive propeller* is proportional at the cubic law (x^3) of the diameter (blade lengh). Do not confuse with active propeller, in this case it's on (x^5) law.
*The "rule" of the passive propeller is played by the plane in the flow, wings are simulating poor efficiency blades.
That mean it takes 1.4^3 (2.74) less power taken from theese used to fly, to roll the D-9 than the Ta-152, at the same roll rate. This is of course a very approximate formula, rather a tendency, many others thinks could interfere before.
Well, 2.74 times roll rate reduction seems a hudge decrease. It's not impossible that the Ta-152 could take more power over the global system to feed it's roll compared to the Dora. But there's no miracles in the world of physics. Until the opposite is proven, Pitts are rolling much faster than 747th's...
Regards
This fact is logical and mentionned by JY Lorant works, a more than enough qualified and well known specialist over the FW family, i hope.
Everybody that went in school can remember (or should remember) the ice skater problem, that turning faster on itself when arms are closer to the body.
I never saw precise numbers, but we can try a "scientifical" approach.
First, and foremost in our case (dogfight) the roll rate is not such an important as the angular acceleration, and control respunse. I would say it's 100 times more important to launch an immediate roll and stop or invert it at only 60°/s such immedialtly, than reach 240°/s roll rate at "not before" the 26-27th full barell, with 9°s per 360° acceleration-deccelaration increase rate. This is just an example, showing that "max roll" alone without any roll (radial) acceleration is useless.
This is the inertia moment problem, proporionnal to M. L². Since the new wing will be heavier and 14.8/10.51 bigger this would affect (increase) resistance to movement at quadratic law (x^4) at least. So (1.4)² for L, no problem it's in the formula, 1.4² also for wing weight M, considering with simplification that wing structure density (kg/m²) would to be kept at same dimension. Well I have intentionnaly negligated the fact that "all proportions kept" a 1.4 bigger wing should have 1.4² more aera and 1.4^3 more weight, by leazyness, but it's rather a conceptual than physical problem. Moreover the high aspect ratio new wing would be affected by a serious adverse yaw, that should have been much lighter on previous short wing variant. (Ask to glider's pilots).
So before considering any rate of roll problem, the plane (Ta -152) with the new bigger wing would have very long and sluggish reaction to the control column, and very poor radial acceleration compared to the "normal" Dora.
Now, considering the established roll rate in itself, it has little relationships with the inertia moments. See high roll rate of the P-38 and french Corsair with assisted ailerons. But the time for them to use this astonishing roll, a lot of things could be done against them in the meanwhile with Yak-11s, P-40's and even A 6 Texans at la Ferté Alais Warbirds collection base.
The roll rate is depending on a lot of factors, such as wing shape, aileron design, wing rigidity, and mobile to fixed aera ratio...
In that case the champion in all warbirds category should have been the 1934's Polikarpov I-16 tip 4 with 360°/ in 1-1,2s. For "modern" fighters probably the La-7 with 9.8% mobile aeras (less than 6% for the 109).
Otherways: my proposal is to modellise the whole plane as a two bladed wind turbine with very low output. Applying Betz forulas, all that we see is that power absorbed by the passive propeller* is proportional at the cubic law (x^3) of the diameter (blade lengh). Do not confuse with active propeller, in this case it's on (x^5) law.
*The "rule" of the passive propeller is played by the plane in the flow, wings are simulating poor efficiency blades.
That mean it takes 1.4^3 (2.74) less power taken from theese used to fly, to roll the D-9 than the Ta-152, at the same roll rate. This is of course a very approximate formula, rather a tendency, many others thinks could interfere before.
Well, 2.74 times roll rate reduction seems a hudge decrease. It's not impossible that the Ta-152 could take more power over the global system to feed it's roll compared to the Dora. But there's no miracles in the world of physics. Until the opposite is proven, Pitts are rolling much faster than 747th's...
I don't know, but it has more probability to happen than with short wings. It's still not a prove, i have practiced some gliders that had a much more impressive aspect ratio than Ta-152, without encountering (fortunatly) any problem with that. But again, this is rather a conceptual problem (wing aeroelasticity, water ballasts, efforts repartition etc...) than purely geometrical.
Regards
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Had French Corsairs really got power-assisted ailerons? It's very interesting.
I know that Lightnings had boosted ailerins and probably Do-335 had the same, but Corsairs?
As far as I know they had spring tabs (Flettner tabs = servo trimmers) on their ailerons as F6F-5 had. But looking on Ta-152H schemes I see that tabs on them look like Flettner tabs.
And one more note: as far as I remember P-47N had a higher roll rate than P-47D. But its wingspan was bigger than P-47D wingspan.
FLYBOYJ
"THE GREAT GAZOO"
The F4U actually had a "boost tab" installed on the inboard portion of the aileron. The tab moves in the opposite direction as the aileron, lightening controll forces and increasing mechanical advantage. It was actually a servo tab.
drgondog
Major
I agree with all Altea's basic points with few small reservations. I would observe that a.) the rolling moment of intertia is very important, not only to the final sustained roll rate but also the initial acceleration. Having said this, the aileron forces are paramount, and b.) also the control forces... so aileron area as a percentage of wing span and the amount of stick force required to initiate and control the sustined roll - as well as rudder effect to offset the yaw introduced by the roll (the incremental increased lift on the up wing also increases the drag on that wing - as Altea mentioned)
The effect of "Spinning Rotors" to the Euler equations is linear with respect to Roll angular momentum - positive contribution in one roll direction, negative in the opposite direction.
Aeroelastic response due to the inputs of the ailerons and rudder in roll influences the aerodynamics and controls
Although the general approach Altea uses to compare the two a/c is very sound, the overall effect of wing span comparisons would need much refinement to drive a true analytical result. He prefaced his comments in a similar way - just simplifying for general understanding.
For example - the actual wing of the Ta 152, while increasing in span, is also tapered and the airfoil section t/c reduces spanwise, thereby reducing the effect of weight of the added wing span well below a 'cube law' relationship to span,
Equally interesting is a question of the spanwise distribution of lift comparison between the two wings, as well as the internal structure/stiffness... both are important when the questions surrounding aeroelastic effects and flutter arise.
The effect of "Spinning Rotors" to the Euler equations is linear with respect to Roll angular momentum - positive contribution in one roll direction, negative in the opposite direction.
Aeroelastic response due to the inputs of the ailerons and rudder in roll influences the aerodynamics and controls
Although the general approach Altea uses to compare the two a/c is very sound, the overall effect of wing span comparisons would need much refinement to drive a true analytical result. He prefaced his comments in a similar way - just simplifying for general understanding.
For example - the actual wing of the Ta 152, while increasing in span, is also tapered and the airfoil section t/c reduces spanwise, thereby reducing the effect of weight of the added wing span well below a 'cube law' relationship to span,
Equally interesting is a question of the spanwise distribution of lift comparison between the two wings, as well as the internal structure/stiffness... both are important when the questions surrounding aeroelastic effects and flutter arise.
Yes they are. I spoke with some Aeronavale pilots demonstrating the plane since mid 80ies. I was told "It's Fun. At beginning it's (roll) slow but then pshhhhhhiit , surprisingly it goes boosted. But there's a limit, it's still not a Yak-11 anyway." They were practicing Yak because it's cheaper, to maintain handling level on warbirds.
