Brewster Buffalo dive speed and handling

[WMLute]

I just encountered a Brewster today in an F4F. I had 2K of alt and obvious E (him getting off a climb, same as me. Probably me going about 300 and him going 250. I pull vertical and he does too, except he climbed right up to me and pinged the crap out of me. Any other plane I would have been  dead .

I had 2k alt in a jug25 last night vs. a brew that had just finished a fight.

Merged, went vertical and like you said it climbed right up there with me.
(gentle merge w/o much Energy bleed btw)

There is indeed something not quite right about the Brew if it can out zoom a jug when it has less alt and e.

[dtango]

I had 2k alt in a jug25 last night vs. a brew that had just finished a fight.

Merged, went vertical and like you said it climbed right up there with me.
(gentle merge w/o much Energy bleed btw)

There is indeed something not quite right about the Brew if it can out zoom a jug when it has less alt and e.

Why do you think it's wrong?  Please explain .   And please don't tell me because the Jug is heavier thus it has more "N-R-G" .

[Ardy123]

I had 2k alt in a jug25 last night vs. a brew that had just finished a fight.

Merged, went vertical and like you said it climbed right up there with me.
(gentle merge w/o much Energy bleed btw)

There is indeed something not quite right about the Brew if it can out zoom a jug when it has less alt and e.

I've experienced this too, but I have always thought it was because the Brewster did a little dive, prior which led me to think that the e-retention of the Brewster was in some way off.

By the way a p47D-40 should out climb a Brewster

[dtango]

Are you talking zoom climb or steady climb? Why do you think the p47d40 should outclimb the brewster?

[dtango]

double post.

[BnZs]

Are you talking zoom climb or steady climb? Why do you think the p47d40 should outclimb the brewster?

Uh, because it does okay?

According to the chart, the Jug DOES outclimb the Brewster.

The ratio of thrust-to-weight is better, as evidenced by the D40's superior climb rate.

The ratio of thrust-to-drag is better, as evidenced by the D40's vastly faster top speed.

Thrust is good, weight and drag are bad, the more thrust you have in relation to these two, the better in a zoom, right?

So how can the Brewster BEGIN to match the zoom performance of the D40?

[Plazus]

Dont forget that weight does help with E retention. The heavier an object, the greater the mass, and thus, the better it stores momentum. This explains great E retention in planes like the Jug, P38, and Mossie.

I just dont understand why the Brewster zooms so well if it is lightweight and underpowered? Then there are people saying that the Brewster has some instability problems in real life that is not present in game.

If somone is knowledgeable about this, please shed some light for me.

[dtango]

So many things amiss with statements above but I'm headed out the door to see a movie with the kids!  No time to reply.  Will be back later .

[Stoney]

I had 2k alt in a jug25 last night vs. a brew that had just finished a fight.

Merged, went vertical and like you said it climbed right up there with me.
(gentle merge w/o much Energy bleed btw)

There is indeed something not quite right about the Brew if it can out zoom a jug when it has less alt and e.

Lute and Spikes, with respect to both of your experience, did you guys film these engagements to know definitively the relative e-states of yours and the other aircraft?

Power Available - Power Required = excess power.  Excess power equals the ability to either accelerate or climb.  So, what we should consider is whether or not there are situations where a Brewster may have more excess power than the Jug.

[Stoney]

Dont forget that weight does help with E retention. The heavier an object, the greater the mass, and thus, the better it stores momentum. This explains great E retention in planes like the Jug, P38, and Mossie.

I just dont understand why the Brewster zooms so well if it is lightweight and underpowered? Then there are people saying that the Brewster has some instability problems in real life that is not present in game.

If somone is knowledgeable about this, please shed some light for me.

Personally, I think the Jug stinks at retaining energy, unless the nose is pointed down, and I've fought it in just about every possible situation in this game.  Its heavy, and the engine is constantly having to work hard to keep the big, fat, beautiful hunk of American Iron airborne.  The advantage the P-47 has it that it keeps 2200-2800BHP under the hood.  A large part of the reason the P-38 and Mossie "retain" energy as well as they do is because they have two engines creating a lot of thrust, not because they are heavy.

You say "I just don't understand why the Brewster zooms so well if it is lightweight and underpowered?"  Is the Brewster underpowered?  What's your definition of "underpowered".  You've got a 5000 lb aircraft with 940 HP compared to a plane that weighs 14,000 lbs when its svelt, that makes 2600 HP.  In that comparison, the Brewster has a slightly better power to weight ratio than the Jug.

Honestly gents, if you want to learn about this stuff, do some research on power required and power available.  Then, read up on specific energy and how you can use it to compare dissimilar aircraft performance.

[Stoney]

Last comment...

dTango reminded me of this thread in an offline discussion we were having.  If you read through the entire thing, you'll find the most thorough treatment of this topic on the boards.

http://bbs.hitechcreations.com/smf/index.php/topic,266321.0.html

[dtango]

OK guys, I don't have a lot of time to explain so I'm going to be brief.  I'm headed to Central Texas for the long weekend and playing aero babysitter isn't anywhere near the top of my list of things to do so .

1) Specific Excess Power (Ps)
Ps gives us a measure of the energy rate of change for an aircraft.  Want more info on it you can dig it up from this thread among other places:
http://bbs.hitechcreations.com/smf/index.php/topic,209163.msg2488778.html#msg2488778

The general equation for it is:

Ps = (T - D) * V / W = dh/dt + (V/g)*dV/dt

Honestly I have no idea how you guys can magically estimate what an aircraft's "energy retention" should be in your head without working through what the value of Ps in every situation and flight condition.  For a constant speed climb at least it's easier to calculate but for a zoom I have to resort to numerical methods to solve it to have even a clue because being a mere mortal I can't do the math in my head with the number of variables and non-linearity involved.  You guys are gods to do all that ciphering in your head!  I bow down, unworthy.

To show that E retention is wrong you have to show where the Ps relationship has been violated.

2) F4F vs. B-239
This one is a little easier to explain because we can use the steady climb charts to demonstrate.



As you can see the B-239 pretty much outclimbs the F4F across the envelope in a steady climb.  In a steady climb dV/dt=0 therefore our Ps equation resolves to:

Ps = (T - D) * V / W = dh/dt where dh/dt is the rate of climb

As alluded to by Stoney specific excess power tells us about the amount that T>D which can be used for accleration or steady climb.  Because the F4F W > B-239 W we can safely assume that the B-239 will probably also out zoom an F4F just as the RoC difference indicate for steady climb.

3) Well what about the P-47's you say?
That's a little more complicated.  Firstly let's just plot out a couple of RoC charts.





First thing to notice, without WEP the P-47 D11,25,40's are outclimbed by the B-239 roughly below 5k at Military Power.  But at WEP for the most part the D11 (marginally except below 5k), D25 & D40 all have better RoC's.  So there must be something wrong with the B-239 then right??? Not so fast.

a) the speeds that you're comparing the climbs matter.  The charts above are at best RoC for each aircraft and they are different.  If the P-47 however is climbing in a steady climb but at a lower speed than it's best climb speed then it's RoC will get worse because of greater induced drag.

b) this is different than the F4F vs. B-239 case because the P-47 is much heavier bird than the B-239 so you have to understand what the impact of that's going to be in an accelerated zoom climb.  The forces in the direction of travel in a zoom climb resolve to:

F = ma = T - D - W*sine(climb_angle)

At steady climbs climb_angle is small therefore the impact weight is lower.  However where climb_angle increases the impact of weight increases.  In a zoom climb the climb_angle is pretty high which means weight has much more of a detrimental impact on zoom climb peformance.  So it's totally conceivable that the B-239 could zoom better than the P-47 D11, D25, & D40.  Again I have no idea how you guys can factor all that in your head to know what the impact is for sure.  To figure out how the above relationship varies I have to resort to numerical methods for resolving integration of partial differential equations to even estimate it.

4) But doesn't greater weight mean more mass which means heavier things retain energy better?
This is a partial truth which is wrongly applied to aircraft.  Where airplanes are concerned increased weight overall reduces zoom climb performance.  See mace and my posts in this thread for an explanation of this fact (Stoney - thanks for pointing the thread out):

http://bbs.hitechcreations.com/smf/index.php/topic,266321.msg3328531.html#msg3328531

Bear in mind that I'm only assuming 1g load factor in all the above.  In n>1 Apples to apples this would generally make it even worse for the heavier plane.  Bottom line for me: Could there be something wrong?  Yes.  However maybe folks should start asking why what you observe is actually RIGHT instead and look for the explanations for why it's right instead of assuming it's wrong.

[dtango]

I'm paying special attention to your post BnZs because you should know better !!

Uh, because it does okay?

According to the chart, the Jug DOES outclimb the Brewster.

The ratio of thrust-to-weight is better, as evidenced by the D40's superior climb rate.

See my post above for explanations.

The ratio of thrust-to-drag is better, as evidenced by the D40's vastly faster top speed.

You've over-generalized.  This is true for a portion of the flight envelope.  However thrust and drag are nonlinear across the entire peformance envelope and you can't assume this relative relationship between planes remains the same across the entirety of the flight envelope.

Thrust is good, weight and drag are bad, the more thrust you have in relation to these two, the better in a zoom, right?

Yes this statement is true.  But for our specific situation you're assuming you know what the values of thrust and drag are and discounting the effect of weight.

And yes, my fingers do get really tired of typing all this stuff to you too!

[BnZs]

I'm paying special attention to your post BnZs because you should know better !!
See my post above for explanations.

Uh, actually in this case I don't really understand.

Ok, first, how I define a zoom climb for our purposes-Straight vertical, or darn close to it. The wings are unloaded or close to unloaded at this sort of angle. The way it usually gets down in combat. I can easily see how the Brewster might climb better at 120mph IAS than the D40, even though the D40 climbs better at its Vy. But I don't think we are talking about an angled climb when we speak of vertical performance generally, we are talking about maneuvers that involve pointing the nose at the noonday sun until one of you runs out of airspeed. Lighter wingloading would seem the Brewster's only performance advantage over the D40. In this case, I don't see why lighter wingloading would come into play as an advantageous factors, cause like I say, the wings are unloaded anyway. This is the sort of climbs where people are finding Brewsters with lower initial airspeeds chasing them up for surprisingly long amounts of times.

You've over-generalized.  This is true for a portion of the flight envelope.  However thrust and drag are nonlinear across the entire peformance envelope and you can't assume this relative relationship between planes remains the same across the entirety of the flight envelope.

Yes this statement is true.  But for our specific situation you're assuming you know what the values of thrust and drag are and discounting the effect of weight.

Well, like I say, I thought better climb rate was a pretty dead indicator of better better thrust-weight. And I thought top speed was a good indicator of thrust versus drag for the airplane at low AoA. An airplane zooming straight up is at low AoA, in fact like I say, its unloaded. As for weight, isn't weight unimportant except as it relates to thrust? Same thing with drag? So I still can't see why the D-40 doesn't hold all the cards in vert performance against the Brewster.

Edit: I was a little stunned to learn that the Brewster's charted climb rate is so poor. Just from playing around in the pond with them, I had figured they'd have roughly the same climb rate as an A6M5b. And Lute posting also caught my eye...that's not some random yahoo who can't judge E states speaking there.

[Wmaker]

Then there are people saying that the Brewster has some instability problems in real life that is not present in game.

There are lot of people saying lot of things on this BBS and everywhere else. Regarding the Brewster on this BBS roughly about 5% of the comments stated have anything to do with reality.

Regarding the stability, the stability problems were in the longidutinal axis on the later models when the CoG was close to it's aft-limit. This happened when the plane was close to it's maximum take-off weight ie. the aft fuselage tank was full of fuel. These problems have absolutely nothing to do with the variant we have in the game.

A good source for further describtions is Dean's America's Hundred Thousand.