Brewster vs. P-38 Zoom test

[Boozeman]

Hmmm, whats all this fuzz about the B239 lately? 

[Bubbajj]

When you look at a the numbers, assuming that the Brewster is using the same engine as the FM2 and the F4F, you can see why a Brew' might seem to have an obviously better "climb" in some circumstances. An F4F with 4 guns and half a tank of gas weighs in at 7503#. An FM2, same configuration weighs 7108#. The Brewster weighs 5161#. That's a whole TON less. Power to weight, a Buff' should be a monster. Given the way an FM2 and an F4F can dance around, it's no wonder a Buff can turn the way it does. If the numbers are correct, this really isn't a mystery.

[Bronk]

None of you are fooling anyone.

This, coming from you scorpion boy?

[Grendel]

Even the Finnish records dont say much about performance other than it didnt have trouble against Hurricanes and was showing age by the time of the La-5 or Yak 9.

And you base this on what evidence?
There are complete flight tests with several airframes, comparisons to Finnish test's numbers to Brewster factory papers, technical journals and books researching the performance, flight capabilities, handling and about every possible detail in the plane.
But well, if you haven't seen it, it doesnt exist?

[uptown]

Hmmm, whats all this fuzz about the B239 lately? 

Basically the thing it racking up kills, so clearly it's over modeled. 

[Wmaker]

I just did. Maybe you cant work it through but Im sure there are some that can.

Heh, ok.

Considering the original post of this thread, your opinion on whether or not the Brewster should have been included to the planeset is totally irrelevant when it comes to this thread. As is  that anecdote you posted even though it is very interesting bit of history and very interesting read. AH has neither the "AVG-edition" of the P-40 line nor the Buffalo Mk.I.

I very seriously doubt there was all that much special about the Brewster that Finland had in their defense than any of the other Brewsters from the same factory. You should bear in mind that the Finnish aircraft had only 900 h.p. compared to 1200 h.p. available to the model tested in the 'anecdotal' competition with a P-40.

You don't think 800-900lbs does anything to the maneuverability of an aircraft? I don't have my AHT at hand as I'm out of town but IIRC G105-Cyclone didn't produce 1200hp. The take off power that I seem to remember is 1100hp. So based on that Buffalo Mk.I would be roughly 800lbs heavier while having only 100hp more. No a very good trade off and totally irrelevant variant when estimating the performance of the B239 we have in AH. Someone with AHT can double check my figures.

Also the P-40 that AVG flew had ~200hp more power compared to the AH's P-40B and also at least ~480lbs less weight as AH's seems to be currently over weight by that amount. So the comparison is totally apples to oranges. But because of the way you posted it, someone who doesn't know these facts will compare AH's Brewster to AH's P-40B and more confusion is created. That is why I dubbed the link as "noise" as far as this thread is concerned, even though it is an interesting historical account.

[Karnak]

One thing I have observed through my decades of interest in WWII aircraft is that most people have expectations that the differences in performance between one extreme, say A6M2, and another extreme, say F6F-3, were much greater than they were in actuality.   In a dive, the F6F-3 will pull away from the A6M2, but it won't end up a mile ahead after a short dive like people seem to expect.  Generally, whatever your intuition tells you the difference should be in a dive or zoom test, quarter it or eighth it and you might be in the ball park.

[Becinhu]

Anecdotal yes, germane to this discussion?  No. 

ack-ack

The *&^ dang Germans ain't got nothing to do with it!
Sheriff Buford T Justice of TEXAS!!!

[dtango]

That right there proves your true agenda and lack of real argument.

No I pointed out the aircraft the engine came from so you could look up the power straight away. Nice attempt at nit-picking one possible intention while ignoring the real and stated reason.

You and three others (now four) in this thread specialize in bloviation only on this BBS with a side-helping of self-congratulation. None of you are fooling anyone.

I disagree with your allegations in your response, but don't see any value in further debating them because it will just ratchet up the rhetoric.  There is a topic you bring up that I want to elaborate on however and that’s my agenda.  Yes I do have one.

In my experience the majority of FM disputes follow this approach:
1)  I think theres’ something wrong with [blank].
2)  I don’t have to prove why or how my assertion is right, but someone else must prove why or how my assertion is wrong.

Philosophically I have a problem with this approach. 2ndly let’s say you know why or how someone’s assertion is incorrect but to demonstrate it means painstaking effort to explain it.  If you want to correct the assertion I see two ways of doing it:
A)  Spend all sorts of time and effort yourself to explain why or how the assertion is flawed
B)  Have the person making the assertion spend the time and effort to work through why or how the assertion is flawed

Which would be more convincing?  I find myself in the camp B nowadays.  Two reasons worth mentioning are IMO 1) someone is more easily convinced when they discover the flaw for themselves & 2) that someone will actually learn more in the process of discovery.

So yes, I do have an agenda in FM disputes where there is misinformation and that is to hint, needle, prod, question, & cajole folks to prove themselves why or how their assertion is right instead of putting that burden on someone else in hopes they will discover for themselves why it's actually flawed.  If I've come across as a pompous bellybutton in the process then I sincerely apologize to anyone I've offended including you.  I certainly don't intend to come across arrogantly and can see where I can't be the best judge of that because I can't predict how someone will receive what I say & the way I say it.  

In this specific thread I judged that I've had enough "dialog" with BnZs over the years on this BBS that it was OK for me to tease him in what I thought was a good natured way while tossing questions back at him to get him to think.  As complicated as the topic can be I have total confidence he can eventually sort it out and doesn't need me to do so for him.  But if he honestly wanted some help in the process and was really really stuck, then I'd be happy to help if he asked for it.

Tango

[BnZs]

Yeah, I'm a little dismayed by your post to Tango, I don't deserve this. From what I've read, (from stuff YOU posted), the prime factors that influence zoom climb are power vrs. weight and power vrs. drag. I just haven't seen the figures where the B-239 is all that great in either category. Now, not knowing exactly what engine HTC has modeled the Brew with, the only thing I have to go by to guess at these two factors is climb rate and top speed. I'm ASSUMING that ROC correlates pretty strongly with power to weight ratio  (I've heard Hitech say it does), and I'm also ASSUMING that power to drag ratio in level flight corresponds pretty well to thrust drag, because, well, as far as I know it does. Now if you can show me some various detailed and tedious figures on why the B-239 should outzoom the faster, better-climbing Zero, I would be much obliged and forgive the undeserved pictorial commentary. You'll note for instance, you haven't heard me say a thing about the airplane's formidable turning ability, the wingloading figures jive pretty well with what it can do there, so I'd appreciate it if you'd not treat me like an idiot who is doubting the FM because of an isolated combat anecdote or the like.

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

(Image removed from quote.)

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

 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)?


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

[bozon]

...Now if you can show me some various detailed and tedious figures on why the B-239 should outzoom the faster, better-climbing Zero, I would be much obliged...

The Brewster consistently regained 5K.

The Zero consistently regained 4.9K.

This counts as the same zoom. Is your accuracy really better than 100 feet out of a 5000 ft zoom?

[Stoney]

Now if you can show me some various detailed and tedious figures on why the B-239 should outzoom the faster, better-climbing Zero, I would be much obliged...

Because you can't whip up this type of analysis quickly or easily.  What Tango was trying to say earlier is that the burden should rest with the person highlighting the perceived error.  Otherwise, just push the "I believe" button on the assumption that HTC did their part right.  The correct methodology to make this comparison was in the Brewster vs. P-47 thread.  Tango put together a very detailed analysis, that probably took a number of hours.  You want him to repeat that again?

Obviously if the Brewster can "out zoom" the Zero in your test, there is more to the comparison than simply those characteristics you've identified so far.

[dirtdart]

Gents... I am the PERK THE BREWSTER! guy.  That said, a component you are all missing is the cd.  Look it up, you may be amazed, I know I was.  Drag and gravity are what slows a plane down in the vert.  The Brewster is ridiculously slippery.  How they got the airframe that slick, I don't know.  I am a combat engineer, not an aero guy.   

The Brewster does so well because people get into its fight, not staying in the fight of the ride they are in.  This is a tough one to fathom, Wmaker got me to swallow my pride on that several times since the plane was introduced.  Has to do with folks just not taking the time to look at the numbers.  HP has nothing to do with this discussion.  Hell you want to prove that one, do the test with the climb master, a K4.  It has a 1000 hp advantage to the Brewster.  Yet, CO E, the Brewster has a much lower cd and therefore offsets part of the HP difference.  Yes it will not out zoom the K4, but it will remain in gun range until the K4 stalls.  So.....

1.  Stay above a Brewster.
2.  Don't give up E to turn into one, he will reverse and you will die.
3.  Work on your aim and shoot them piecemeal.......
4.  PERK Wmaker. 

[Wmaker]

I have been told that the model in the game was elevated to its current abilities through anecdotal evidence (actually no evidence at all except a verbal "no thats not quite right").

You've been told so? Right, ok. You do realize that not everything that gets told is correct and true. I hope you've already heard about the Santa Claus and Tooth Fairy? If not, you're in for a real shock, sorry.

Anyways, here's the thread discussing about the changes made to the Brewster's flight model in the last version update: http://bbs.hitechcreations.com/smf/index.php/topic,270213.0.html

[THRASH99]

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.
(Image removed from quote.)
(Image removed from quote.)

Since when did zeros and brewsters get WEP?