Hello Milosh
One often hears that the Ta152H's roll rate was not that good when compared to the Fw190 and this put the Ta152H at a disadvantage in combat with Allied fighters.
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.
What was the roll rate of the Ta152H? How did it compare to the roll rate of Allied fighters?
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...
With its long narrow wings would/did the Ta152H suffer from wing flutter in dives?
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