Brewster vs. P-38 Zoom test

[BnZs]

Due to my own observations of the Brewster's vertical hanging ability and the fact that several (non-idiot) AH pilots have commented on that same, I decided to put it to the actual test, against the gold standard of AH zoom performance, the P-38L. For an additional data point, I tested against the A6M5b.

Test consisted of multiple iterations of my usual procedure for testing zoom climb, dive to sea level, speed was allowed to bleed off 'till it reached 375mph IAS, at which point a 3g pull-up was used to bring the plane straight vertical, then shift-x was used to hold the plane in this attitude until it departed by its own devices.

The P-38L consistently regained 5.5K of alt in such a zoom.

The Brewster consistently regained 5K.

The Zero consistently regained 4.9K.


I find the closeness of these results quite startling, in light of the fact that the P-38 is a torque-free, low drag airframe with a superior climb rate-as I said, the gold standard for vertical maneuvering performance. I find the Zeke's inferiority in the vertical flat dumbfounding, since I cannot see a single factor that should give the Brewster even parity with the Zero in this area.

[E25280]

I think it has been said in other threads that you can not equate sustained climb rates with zoom capability.  Sustained climb rates use lift from the wings, whereas zoom climb is only thrust and momentum vs. drag and gravity.

Since your testing methodology is to go straight vertical, there is no lift benefit from the wings, so the sustained climb charts are not a valid comparison or necessarily a good predictor of zoom performance.

[bozon]

What did you expect? that the 38 will zoom into outer space while the zeke stall out after 500 feet?

The difference you got was 600 feet between the 38 and zeke, that is not a little.

[StokesAk]

I am never able to out zoom climb a zeke no matter how fast he is going, that prop will keep him in the air forever, or just long enough to kill me.

[AirFlyer]

As an avid A6M flier I wouldn't hold it light in zoom, usually one of the few things that actually scare me to zoom against are P38s. Few other things will match if the speeds are close and the original starting distance isn't too far.

This is my experience in MW of course, I'm not entirely sure how she hold against all the late 44' and up planes.

[Soulyss]

I'd be curious to see what the result were at other climb angles, however I imagine consistently getting the same angle on all three airframes would be a little difficult.

[Stoney]

Surely after all the discussion in the Brewster vs. P-47 thread a few weeks ago, you can sift through it, and understand a better methodology for comparing those three aircraft.

[dtango]

BnZs, the problem is you didn't learn gazinta's in math...you know like Jethro Bodine says- 2 gazinta 6 three times, 3 gazinta 12 four times, velocity gazinta's thrust and drag,...weight, thrust, drag, and velocity gazinta's zoom climb performance...etc.  So let me bet next to line up and try and slap some "gazinta" sense into you!

http://www.youtube.com/watch?v=i0GW0Vnr9Yc



Let's commence with the slapping shall we???

Due to my own observations of the Brewster's vertical hanging ability and the fact that several (non-idiot) AH pilots have commented on that same,

Presuming that there is an FM problem based on this is a logical fallacy- either an  “Appeal to Authority” or a reverse “Ad Hominem”.  “An appeal to authority is an argument from the fact that a person judged to be an authority affirms a proposition to the claim that the proposition is true.”  Deductively the strength of an argument lies on the soundness of the logic not the traits of an individual.  You can be an authority on a subject yet be completely wrong if your logic is wrong.  In our B-239 case no “authority” has yet to lay out an FM dispute on the B-239 based on sound physics logic.

 

I decided to put it to the actual test, against the gold standard of AH zoom performance, the P-38L. For an additional data point, I tested against the A6M5b.

Blah blah blah...test results...blah blah blah

Inconclusive for various reasons, some already mentioned.  Let’s demonstrate this by answering your questions with my favorite....more questions!

1) If the FM is wrong, how do you know which airplane the FM is wrong for- P-38L, A6M5b or B-239? 

2) How do you know the relative difference between the aircraft in question of thrust, drag, velocity, and weight does not change between steady best rate of climb vs. a zoom climb?

3) What were the weights of the aircraft (because that’s one of several variables that are terribly important)?

4) What is the rate of energy bleed of each aircraft during the 3g wings level pull-up to vertical and its impact on final zoom climb performance (hint: weight is a big factor in this)?

I find the closeness of these results quite startling, in light of the fact that the P-38 is a torque-free, low drag airframe with a superior climb rate-as I said, the gold standard for vertical maneuvering performance. I find the Zeke's inferiority in the vertical flat dumbfounding, since I cannot see a single factor that should give the Brewster even parity with the Zero in this area.
(Image removed from quote.)
(Image removed from quote.)

First regarding the closeness of the results:  what did you think the delta would be and why?  For instance let’s even assume that steady ROC differences mean something.  Wow, by looking at the charts that gap between the B-239 vs. the other airplanes is huge therefore the climb differences are huge!  That’s very deceptive though.  Here’s a really simple & crude example to illustrate using sea level ROC from the charts:

plane   fpmin   fps   25_s   d_ft   d_yds
b239   2850   48   1188   ---     ---
p-38l   3700   62   1542   354   118
a6m5   3350   56   1396   208   69

In 25 seconds of climb the a6m5b has an outstanding 208 ft / 69 yd advantage over the B-239.  Better yet, the “gold standard” P-38L has an incredible whopping 354 ft/118 yd advantage over the B-239.  Woooweee, now that’s something to write home about!!  The point is what on earth are you trying to compare and what quantitative values will that result in?

Second, here’s how I understand your argument:

A)  The B-239 has a worse steady rate of climb compared to the A6M5b & P38L
B)  Because best ROC is worse in the B-239, zoom climb should also be worse vs. the A6M5b & P38L
C)  My zoom climb test results show that B-239 zoom is different than steady ROC therefore the B-239 is wrong

The problem is that you presume that statement B is true.  However to show that statement B is true, you have to show that you’ve answered my question #2.  Until you do so it’s obvious why you “cannot see a single factor” that COULD give the B-239 even parity with the Zero because you haven’t gone through the analysis and eliminated all the factors yet.

I'm not saying there isn't anything wrong.  What I am saying is that the bar is set high to actually prove that something is wrong.

Slapping finished.  Next!

Tango

[Ghosth]

Dang Dtango, you done good!

[Wmaker]

Good post Tango.

1) If the FM is wrong, how do you know which airplane the FM is wrong for- P-38L, A6M5b or B-239? 

Yep, this was my first thought as well.

I'm not saying there isn't anything wrong.  What I am saying is that the bar is set high to actually prove that something is wrong.

Totally agreed. I'm not either, even though several people have implied that I'm somehow "defending" "my ride" ie. saying I'm biased. I've never said there can't be anything wrong. I just get irritated when the argumentation and logic is usually fairly flawed and the (I'm not really talking about this thread but the previous threads/posts.) knowledge of the subject matter is non-existant. There are so many people that have a lot to say about the Brewster but they don't know what they are talking about. It gets rather frustrating when there's roughly 5% signal and 95% noise.

The biggest reason (along with the Finnish community) why I've been flying this sim for so long are the flight models. For me, it's very important that the planes are as accurately modeled as they can be. I'm not here only to "win" in "a game". I'm here to "fly" the virtual counterparts of these planes. So there's really nothing in it for me if the plane I fly is somehow unrealistically better than it should be, on the contrary, it would be something that would drive me away.

The coolest thing about this sim is that the planes match their real life performance figures so closely. I really don't care were the radar alt/ranges are set up or anything else really. I'm just here to fly the planes. Of course those other things that I mentioned are important in creating action between players. But as long as there is action I really don't worry much about them. Ok, a bit OT, sorry.

If we take a look into the basic equations of speed and climb rate and think about the parameters that are basically not debatable (power output, wet area, etc.). If the max. climb rates and max. speeds match the real life data, that alone rules out quite a few things that can be wrong.

If the basic performance figures match, the only (plausible) thing that could cause better real life zoom climb performance on top of my head is wrongly shaped prop efficiency curve. I mean something that would be close to 1.0 at speeds below the sustained climbing speed. If the prop eff. would be at realistic levels at sustained climbing speeds and above but way too high at low speeds. This would enable a plane to "hang on its prop" better but at the same time produce realistic climb and speed performance. I still think that the effect of too high prop eff at low speed would be minuscule in a test of this type due to the short time spent in this speed region due to the vertical climb angle because the thrust to weight ratio would still be very very far from 1:1.

Of the WWII fighters, I've only seen prop eff curve for BF109G and even for that plane there is significant variation on the values between two different sources. So because of the fact that this type of data is quite rare and most probably doesn't even exist nowadays for all the planes in AH, it could be possible that there are some differences in thrust at different speeds in AH compared to real life. On the other hand, I have full confidence in Pyro/HT's ability to approximate things like this very accurately.

From flying faster planes with higher wing loadings like the Dora, I really haven't experienced anything out of the ordinary when it comes to Brewster's performance.

Tango, if I talked total BS here please slap away.

[Stoney]

...real life zoom climb performance...

What would this be anyway?  I've never seen any quantitative data on "zoom climb" rates among the various aircraft.  The definition of "zoom climb" itself is dubious at best.  We know that, in general, it refers to an aircraft climbing faster than its sustained rate as a result of excess energy.  Beyond that, we have no real idea how to characterize it.

There's really no way to dumb down this issue.  It is very complex and requires very detailed and focused analysis.  The task is exacerbated by the "retains its energy better" myth that heavier aircraft somehow have an advantage here.

[Wmaker]

The definition of "zoom climb" itself is dubious at best. 

Agreed.

I worded what I meant rather poorly obviously. Sorry.

What I meant to say was that the virtual aircraft would climb slightly higher in BnZs' test if it would have unrealistically high prop eff at low speed region compared to its real life counter part which obviously would have its "real life" prop efficiency through out the speed range.

I'm quite sure you still understood what I meant initially, though.

[Stoney]

I'm quite sure you still understood what I meant initially, though.

Yes.  I actually meant my comments to compliment yours, but didn't word them very well. 

[Yeager]

All I can tell you is whats in the game, and fighting the little buffalo thingy is like grabbing a tiger by the tail.  Lets thank gOD that at least they never installed 4x20s in the damned thing.

[dtango]

Dang Dtango, you done good!

Ha!  Channeling your inner Uncle Jed I see 

Tango