Fw190A8's speed/climb

[Xasthur]

Xasthur... welcome to the world of Bf-109 pilots. How do you think I feel in my Bf-109G6? Keep in mind, I NEVER take Gondolas.

Haha, look at my avatar mate. I've been flying 109's since day one 

[RRAM]

you wrote that or your lawyer ? 

lol Straffo. I just thought that with the past I have in this forums, and the fame I (deservedly) earned some years ago, I had to clearly explain where do I stand,what I wanted this thread to be like (and what I didn't want it to turn into), and that I like AH2 and HTC's work. And I had to do all that before I started writting about the topic itself.

It's also true that many discussions concerning german planes have turned into ugly debates with personal attacks involved. I wanted none of that here, and so I politely asked everyone to keep this civil and to discuss facts only. Something, BTW, that I think so far we have achieved between everyone.

[RRAM]

Does that help a lot, or just enough to be noticeable?

donkey

It helps a lot, it's noticeable, and it's done automatically . with 100% fuel load, the auto system drains AUX first, AFT second, FWD in the end. It's the way the historical Fw190A8s drained their tanks aswell. Burning the fuel in the aft tanks moved the plane's CoG forward, and the Fw190 handled much better with that CoG's change. And so does AH's 190.
Something I liked a lot when I came back to AH2 was noticing that at lesser fuel loads, the tanks weren't equally loaded (as it used to be in AH1), but they are loaded according to the plane's needs. For instance, if you take 75% fuel you won't get 75% in each of the tanks, but the AUX tank wont' be even loaded, while the FWD is 100% and the AFT is partially loaded. The plane ,so, starts already with a good fuel weight distribution that helps it's maneouverability.

Try it offline: drain in FWD-AFT-AUX order ,and do some maneouvers. Compare the handling with the 190 draining tanks in the correct order and you'll see the difference by yourself.

[BnZ]

Here is what I don't understand...

Removing weight from ahead of the CG of the aircraft would move the CG backward somewhat, which would reduce stability in the pitch axis, and reduce the amount of downforce the horizontal stab needs to produce to the aircraft in straight-and-level flight or change the pitch angle...doesn't this reduction in downward force needed from the tail to hold change pitch angle actually make for a somewhat reduced load on the wings? I thought this was the justification for canard aircraft designs vs. conventional tail aircraft, despite the former's stability problems.

[Stoney]

Here is what I don't understand...

Removing weight from ahead of the CG of the aircraft would move the CG backward somewhat, which would reduce stability in the pitch axis, and reduce the amount of downforce the horizontal stab needs to produce to the aircraft in straight-and-level flight or change the pitch angle...doesn't this reduction in downward force needed from the tail to hold change pitch angle actually make for a somewhat reduced load on the wings? I thought this was the justification for canard aircraft designs vs. conventional tail aircraft, despite the former's stability problems.

Well, a plane loaded at the aft limit of the CG envelope reduces trim drag, and allows the plane to fly at a lower angle-of-attack, which reduces profile and induced drag.  So, two equivalent aircraft, at the same weight, one with a load at the forward limit of the CG envelope, and one with a load at the aft limit of the CG envelope; the plane loaded at the aft limit of the CG envelope will be faster.  Obviously we're talking about a small increase in speed here.

But, I would think that the better handling with the aux tank empty, while partially due to CG issues, can also include some benefit just because the plane is lighter.

[TimRas]

... and reduce the amount of downforce the horizontal stab needs to produce to the aircraft in straight-and-level flight...

Tail load does not have to be down for the whole aircraft to be stable, in most cases it is up.

[Charge]

"I did read it from the beginning, but apparently forgot you wrote that.  I do have 2 separate Lednicer articles, both of which include the 190.  You may have both."

I don't. I only have the EAA Jan 1999 article. I didn't know there were two of them...

"Well, it talks about the wingloading, wing geometry, coefficients of lift, etc.  What would engine cooling and prop effects have to do with the aerodynamic advantages of the smaller wing?"

The article mentioned above tells about modeling the whole airframe and in both Anton and Dora the cooling system is built around propeller spinner, where as in P51 and Spitfire the cooling drag is located differently. Since propeller can effect the stall characteristics the propeller probably has an effect on cooling drag too. IIRC some Antons (or Fs) were tested with cooling fans with more blades but while providing more cooling they also increased drag (IIRC that is). That may also give a clue of how much the propeller actually affected the cooling drag and thus the total drag of the airframe. I brought this up because I'm interested about the total drag figures of 190s.

But as I wrote earlier the venting of the cooling air is also one factor which needs to be considered to have a good idea of the actual cooling drag of a radial engine and Lednicher report does not offer any conclusion to that. It is just a calculation from a 3D model.

I brought this up before because I'm interested about the total drag figures of 190s and it would be interesting to calculate what would be its top speed in theory and what are the factors that would make it to exceed it or fail to achieve those figures. Being crappy with maths I only hope that somebody in addition to Mr Lednicher would provide such interesting analysis.

BTW if you look at the Figure 2 in article mentioned before it escapes me how the P51 and FW190 can have nearly identical Cl plots despite the radical difference in their airfoils, both NACA profile selection and in size? And what would they look like with different speeds and AoAs? That is what I'd like to see and that is what that article leaves totally open. I'm sure Mr Lednicher would have more data on the subject and trying to squeeze it all in a few pages in a magazine would be impossible so he had to use the space efficiently -resulting in an interesting article with little new to offer for enthusiasts like us.

-C+

PS. I have posted this earlier but maybe this is more appropriate place for it: http://findarticles.com/p/articles/mi_qa3897/is_199808/ai_n8826530/pg_1

PPS. Also notice that the trim drag is further reduced by the tailplane which moves as a whole reducing form drag.

[Denniss]

Some A-9 and maybe some F-9 were tested with a 14-bladed cooling fan instead of the standard 12-blade fan. It did not improve cooling (at least not really noteable) but required even more power to be driven so they reverted to the standard 12-blade fan.

[Charge]

Found this. Particularly interesting is the section describing drag build-up.

http://www.hq.nasa.gov/pao/History/SP-468/ch5-2.htm

Drag increase of 12% between radial and "inline" configuration and added 6.6% for opening the cooling exits.
Thats how I read it.

-C+

[Nilsen]

I fly the A8 alot. Please dont improve it

Few fly it, and i would prefer if it stayed that way