Brewster Buffalo dive speed and handling

[Wmaker]

<sigh> I'm trying to skim it at work will still doing work... but here we go again, with your defensive confrontational attitude.

It is not my job to hold your hand and read it for you. Do your research. Pyro has. If you find something that you think is wrong, make a thought out thread about it.

[Ardy123]

It is not my job to hold your hand and read it for you. Do your research. Pyro has. If you find something that you think is wrong, make a thought out thread about it.

lol, wow, didn't ask you to, only asked a simple question which I believe your previous statement has caused me to revisit and already answer.

[dtango]

As I said before, I have a hunch that it may accelerate in a dive and hold that speed better than I expect. As I said before, I was working on some films, and 'skimming' the docs as we 'furiously type' but as for 'hard facts', other than films, what are expecting as 'numerically defined'?

“Numerically defined” as in actually based on physics vs. the anecdote converter flight model .

I'm not sure on all the math to calculate the 'projected dive speeds' or to calculate the drag created by the wings and fuselage of the aircraft to give an accurate mathematical calculation do you know the formulas?

Maybe we’ll make an aerogeek out of you yet.  Study away my friend and join the darkside!  I have a hunch.  My hunch is after you complete your aerodynamic pilgrimage you’ll come to the conclusion that HT and Pyro actually know a thing or two about aero and the B239 they’ve modeled is remarkably sophisticated & consistent with physics, and that you’ll beg HT to personally induct you into the sacred order of the propeller heads.

Tango
412th FS Braunco Mustangs

[Ardy123]

Maybe we’ll make an aerogeek out of you yet.  Study away my friend and join the darkside!  I have a hunch.  My hunch is after you complete your aerodynamic pilgrimage you’ll come to the conclusion that HT and Pyro actually know a thing or two about aero and the B239 they’ve modeled is remarkably sophisticated & consistent with physics, and that you’ll beg HT to personally induct you into the sacred order of the propeller heads.
Tango
412th FS Braunco Mustangs

lol, I never intended to create a whine thread, I was hard pressed to find stuff on the finish brewster so I asked, others have posted stuff they have found. I never intended to be an insult to HTC, I had a hunch and I wanted facts.

Sadly all I have is anicdotal information, "pilot A says a f4f could out dive a brewster", etc..

[dtango]

I had a hunch and I wanted facts.

You've got it backwards.  Let the facts lead you to your hunch.  How did you develop your hunch to begin with without facts??

Tango
412th FS Braunco Mustangs

[Ardy123]

lol
others agree with me, a hunch is needed to spurn the desire of facts

Stating a hunch is ok.  You're right in saying that's where it all starts.

ok enough with the circular bs, is there a Open source/Free Fluid dynamics simulator, at least I could plug in the NACA airfoil, wing dimensions and the air velocity and calculate how much drag is created by the wing? This would be a starting point to calculating its dive characteristics.

[dtango]

lol
others agree with me, a hunch is needed to spurn the desire of facts

Didn't your mother teach you by rhetorically asking you "if others jumped off a cliff would you do the same"?  All hunches are not equal; some are more equal than others , which tell us something about how good or how bad the hunch is let alone figuring out how you actually test them.

ok enough with the circular bs, is there a Open source/Free Fluid dynamics simulator, at least I could plug in the NACA airfoil, wing dimensions and the air velocity and calculate how much drag is created by the wing? This would be a starting point to calculating its dive characteristics.

What flavor of CFD would you like - RANS, LES, or DES?  That's some serious blackbelt aerogeek kungfu when you decide to skip past Kutta-Joukowski and Prandtl and deal directly with Navier-Stokes *whistle*.  Of course you could spend weeks trying to make sense of all that and only get an indication of drag for the wing or you could just look over flight test and wind tunnel reports and get the drag coefficient for the entire airplane like this...



...or drag polars like this....





...or even see how closely the B-239 in AH diving matches a real life ~5500 lbs F2A-2 diving from 20,000 ft like this..




And by the way, let me know if you find a good CFD program along with all the grid-generators etc. that will run on my pedestrian PC running Vista will ya?  Thanks!!

Tango
412th FS Braunco Mustangs

[Wmaker]

LOL Tango! 

You are far more patient than me!

<S>

AFAIK, that little under 0.03 Cd is after NACA's modifications to the cowling/etc. The original, before the modifications, was at 0.0377. When I plugged basic Brewster's parameters to the speed equation with the estimated prop eff of 0.8 and compared it to the speed obtained in Finnish testing at sea level, I got the Cd of 0,02957.

[Charge]

"The Navy ordered a final 108 Brewster fighters in January 1941. These F2A-3s featured a longer fuselage, increased fuel and ammunition capacity, additional armor and considerably greater weight. "

Thanks Gyrene81. I found this page where the changes were listed and indeed the -3 was longer than -1.

http://www.cybermodeler.com/hobby/kits/ca/kit_ca_4100.shtml

-C+

PS. An anecdote on diving: IIRC Cpt. Karhunen claimed to have dived BW fast enough so that upon pull-up the wingtips were slightly bent upwards, permanently! Afterwards the aircraft was sent for repairs and the wings were fixed/(replaced?).

[hlbly]

OK my hunch the flight model on the b239 is inaccurate . My evidence . In level flight with combat trim applied at 1k alt it ,acceleration was tested from 100 to 250 mph IAS against several other aircraft in AH2 . Results F4u4 super buff less then 3 seconds slower . Against the FW190 a5 and a8 it out performed both of them by a higher margin then the F4U4 was able to out accelerate the Finnish buffalo . Data on the 190 is easy to find . The Finnish buffalo , it is not . Every piece of information regarding stability in turns on the Buffalo , I am able to find . I find another  reference to conflict it . Now since I am unable to find adequate reference on Buffalo's Finland received . Since the majority of the data was provided by the Finns on the 239 to HTC to model the Brewster please allow us to see it to . My last test and the one that really made my eye brows raise . The Brewster EQUALED the D9's acceleration in my test in game . You will reject out of hand any reference provided concerning US versions of this aircraft that say that it is impossible for this to happen . I would say it is your burden to provide the data saying that it can . As far as high tech flight model accuracy , I have to agree . Over all it is the best there is . How ever there are some places I doubt it is as good as it can be . The stall characteristics of the F4U  leaps to mind . I won't post a film of how it stalls in game .http://www.youtube.com/watch?v=n-PwTTQz6Zw&feature=related Here is a film of it going into a stall and the comment on how it is "abrupt with very little warning  little to no buffeting " . Would you care to say that is how it is in game ? I will only argue about objective data with nothing that can be explained by different pilot skill level or any other subjective variable . My hunch , one that I won't argue is that the Finns did well against Russian and end of war German pilots . That the enviable k/d ratio achieved by them with this plane , is a result of the difference in pilot skill . Both the Russian and late war German pilot skill level was uneven at the very best . My hunch is the Finns were probably man for man the best in the world for this time period . Like the saying goes its the man not the machine . If I get any sarcasm or ridicule , I will know why there is always the whine comment . If I can be shown data that confirms my in game test , I will be relieved  . I really expect nothing but sarcasm and ridicule in answer . Wmakers reply where he actually provided data  concerning the 239 showed the 239 with a higher wing loading than an a6m5 . How ever in game it out turns the A6M5 .

[Wmaker]

I really expect nothing but sarcasm and ridicule in answer .

Why should you get anything else? You can't even type coherent sentences using some sort of paragraphing let alone present the results of your testing in any sort of logical manner. I mean seriously, you actually did something that gives you plain straight numbers to present. And you just ramble on without presenting your results properly.

I did some testing myself, here are the results:

Acceleration from 100mph to 250 mph at sea level:

Brewster: ~45s
Fw190A-5: ~32,5s
Fw190D-9: ~30s

Nothing suprising in those results that I can see.

[Stoney]

Any time someone does testing in this game, they should post their methodology along with the data.  That way we can either critique the methodology, or use it to replicate the test, and see if we get the same results.

[Wmaker]

Any time someone does testing in this game, they should post their methodology along with the data.  That way we can either critique the methodology, or use it to replicate the test, and see if we get the same results.

You are completely correct there. It's just hard to bother considering the quality of replies from the "other corner".

My methodology:

Using auto pilot I throttled back over sea at few hundred yards of altitude and let the plane decend on autopilot. Flaps were used on both of the Focke Wulfs so that 100mph flying speed could be reached. As the altitude was around 30-40ft above sea level and plane was stable at 100mph for a few secs I hit full throttle/WEP at the same instant as I started the stop watch and immediately pulled in the flaps as fast as they came in. Speed was observed only from the E6B during the test. As the speed hit 250mph the watch was stopped. The test was repeated two times per plane. Because the variation in the results was so small, two runs were deemed sufficient considering the purpose of the test.

50% Fuel on all planes. Zero fuel consumption, no wind, offline.

[dtango]

OK my hunch the flight model on the b239 is inaccurate . My evidence . In level flight with combat trim applied at 1k alt it ,acceleration was tested from 100 to 250 mph IAS against several other aircraft in AH2 . Results F4u4 super buff less then 3 seconds slower . Against the FW190 a5 and a8 it out performed both of them by a higher margin then the F4U4 was able to out accelerate the Finnish buffalo .

Wall of text responses are hard to read.  Let's just start at the beginning.  Testing methodology and the different numbers your tests vs. wmaker's are producing aside, let me give you kudos for actually testing something and providing data points.  On the logical front however, I'm sorry to say you haven't proven anything except how to collect some data points.  The piece that is missing is your physics logic behind why these numbers are wrong.  That's on you to demonstrate.

Let me throw you another riddle for you to ponder in hopes it'll make you think about the aerodynamics.  Looking at the AH climb charts how come the B-239 will actually marginally outclimb the 190D-9 below 4000 ft, outclimbs the 190A-8 up to 16,000ft, but not the 190A-5 at all? (military power only).

Tango
412th FS Braunco Mustangs

[dtango]

AFAIK, that little under 0.03 Cd is after NACA's modifications to the cowling/etc. The original, before the modifications, was at 0.0377. When I plugged basic Brewster's parameters to the speed equation with the estimated prop eff of 0.8 and compared it to the speed obtained in Finnish testing at sea level, I got the Cd of 0,02957.

Wmaker- I have a "hunch" if you haven't factored in exhaust thrust yet, just a few lbs of it would bring that number to .03 .

Tango
412th FS Braunco Mustangs