Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: Stoney on May 01, 2009, 11:56:43 AM
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Gents,
Just curious as to a method for comparing zoom climbs in-game. I had thought about:
Accelerate aircraft at sea level to 300mph TAS, then hit [alt-x], record peak rate of climb, and altitude at which the autopilot began introducing nose-down pitch trim. Repeat this process at different speeds and starting altitudes.
I've got some other ideas, but they would be very dependent on the pilot, and very hard to maintain precision. What factors from the above method would cause false comparisons?
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Stoney ever consider auto angle?? that would allow equal angles of attack,say zoom at 60 degrees 45 degrees etc.
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Stoney ever consider auto angle?? that would allow equal angles of attack,say zoom at 60 degrees 45 degrees etc.
How would you know you had a precise pitch angle? We don't have any instrumentation in the cockpit to know what pitch angle we're using--it would simply be a swag.
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you might 1st want to define your definition of a zoom climb.......
some people refer to a zoom climb as , as you put it climbing at a set rate of climb angle ( meaning Alt X )
others sometimes refer to a zoom climb as morefiend mentioned, pulling back and climbing at different angles 45 degree nose up, 60 degree nose up, etc...
while even others ( this is my thoughts as well , btw ) think a zoom climb is where you pull up nose above the horizon in a smooth quick motion, anywere from 45 to say 70 degrees while moving along at a significant amount of speed ( 300 to say even 450 ias, or could be slower say 225 ias perhaps ) then unloading the stick ( unloading the G's to either your normal 1 G + , or to a more extreme of "No Load Zoom Climb" meaning you rest the G-meter on zero G's..........
the latter, is your fastest zoom climb possible because of being at zero G's ........ as you begin to level off at the top of your zoom climb, you should still be around 180 to 220 IAS ....which is most times enough speed left to maneuver with if the need arises.....
so, what definition do you want to test towards?
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The simple method of simply diving to 400 or so, doing say a 3g pull up to vertical and using auto-angle works well enough.
A word about "unloading" in a zoom climb...
When the airplane is pointed straight up, the airplane *is* unloaded. The G-meter will be at 0. So induced drag is no longer a factor, the method yields a *pure* test of the airplanes thrust and inertia vs. gravity and drag. And that is what we are after, is it not?
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BNZ, that is why I asked him for his definition of what he considers a Zoom Climb........
got to lay the definitions, the methods/logic and the testing procedures/criteria out 1st........
using Alt-X is just utilizing the games ( the planes ) pre-determined best climb rates/angles..........unless someone ( whoever is testing ) has gone in and changed the preconfigured settings ( but I think these reset each time one launches a new Plane, correct? )
on a sidenote........BNZ, do you think if you were doing 400 IAS at say 3,000 ft alt...and performed a 3 G pull to Pure Vertical Climb.( as you put it a Vertical "Unloaded/ 0 G Climb ) would you climb faster and higher than if you was to fly at 400 ias at 3,000 ft and pull up nose high to roughly 60 degrees/70 degrees above horizon with a very quick & smooth 5 or 5.5G pull and unload to 1G+ or even unload to "No Load/ 0 G climb? lets use a P51B for the test platform...
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Well TC, I don't understand the value of angles other than the pure vertical for testing this.
First, if you can tell that you are at exactly 70 degrees pitch say, you're a better man than me. Perpendicular to the horizon is pretty easy to determine though.
Second, most of these planes will climb with the nose held at very high angles, even below Vy. So where does "zoom climb" performance end and "climb-climb" performance begin?
Third, the idea of pulling up to some high pitch angle, then pushing forward on the stick to 0? That will level you out rather quickly, will it not?
Fourth, I believe zooming straight up best reflects vertical capability as is useful in actual ACM.
Fifth, I believe the only reason people are trying to come up with more complex methodologies is that it has been proven that planes with excellent power-loading perform as well or better in the vert than planes with low power-loading and excellent mass/drag ratio in this game, and some folks just don't want to accept that. :devil
BNZ, that is why I asked him for his definition of what he considers a Zoom Climb........
got to lay the definitions, the methods/logic and the testing procedures/criteria out 1st........
using Alt-X is just utilizing the games ( the planes ) pre-determined best climb rates/angles..........unless someone ( whoever is testing ) has gone in and changed the preconfigured settings ( but I think these reset each time one launches a new Plane, correct? )
on a sidenote........BNZ, do you think if you were doing 400 IAS at say 3,000 ft alt...and performed a 3 G pull to Pure Vertical Climb.( as you put it a Vertical "Unloaded/ 0 G Climb ) would you climb faster and higher than if you was to fly at 400 ias at 3,000 ft and pull up nose high to roughly 60 degrees/70 degrees above horizon with a very quick & smooth 5 or 5.5G pull and unload to 1G+ or even unload to "No Load/ 0 G climb? lets use a P51B for the test platform...
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I would say the most accurate way would be to go Alt-X and pick a standard speed. When the autopilot noses over and climb rate drops below 1,000 fpm stop the test. I believe most planes will even lose some altitude after a zoom climb in autopilot. This would give you identical control inputs and flight paths. Peak FPM climb will depend on a few variables and for me personally isnt that critical.
Your comparing relative stats in order to establish a plane "rank" right? If so the specific flight path need not be perfect.
However, going pure vertical may most accurately depict what you would do in the game.
Strip
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Well, a test of any definition of "zoom" is not reliable unless we can constrain the flight parameters to something that is quantifiable, repeatable, and capable of precision every single test.
I agree TC, that there are different types of "zooms". The problem as I see it is that when using a 3g pull to auto angle, you'll not know how precise your final climb angle is. On the other hand, using auto-climb will allow a lot more precision between aircraft and give something that is repeatable. The reason why I asked the first question was to find out if anyone had any issues with the methodology, or if the methodology wouldn't illuminate anything of substance.
So, if we define the "zoom" as accelerate the aircraft to 300mph TAS and then engage auto-climb until nose-down pitch trim is introduced, does anyone have any problem with the methodology or think that the test will not reveal anything of substance?
Lastly, BnZ, going vertical is not the most efficient method of recovering kinetic energy (speed) and turning it into potential energy (altitude). There are formulas which I will include at a later date that will prove this correct, so for now, you'll have to just push the "I believe" button, or not. The AoA that maximizes lift and minimizes drag is typically close to the AoA for best climb rate, which also corresponds to a speed. In-game, this is close to the auto-climb speed. It changes with altitude due to the drop in dynamic pressure, but typically only changes 5-10 mph. The reason that I believe the auto-climb will be the best way to measure (apart from the precision and repeatability) is that the way the trim system in AH works (to my knowledge), is that pitch trim positions are mapped to speeds for each aircraft. It doesn't matter what attitude the nose is at, the pitch trim matches that of the speed of the aircraft. That's why you have such a hard time getting the nose down when you go "over the top" in a loop, or pulling out of a very high speed dive with combat trim engaged. So, when you engage auto-climb, the game automatically trims the aircraft for that best climb rate speed, or Vy. It doesn't matter how fast you are going. I would imagine that for some aircraft, the pitch trim may reach its maximum trim position during the climb, but we'll have to simply accept that, in my opinion.
Now, to answer your zoom climb to climb climb question, the transition begins when you reach best rate of climb speed out of the zoom. So, when you decelerate to 160mph IAS, for example, out of the zoom, that is the moment that you transition from zoom to climb. That is also the reason why I chose the moment that the auto-climb begins to institute nose-down pitch trim to signify the end of the zoom.
You can call it a ham sandwich test instead of a zoom climb test if you want. I just want to know if this methodology will give us any sort of significant comparison between aircraft? Anyone, please correct anything I've said wrong so far, or criticize the methodology, from an aerodynamic standpoint.
Thanks.
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Pure vertical and some other shallower test like in the first post would complement each other pretty well, I reckon.
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Pure vertical and some other shallower test like in the first post would complement each other pretty well, I reckon.
How do I ensure precision in the pure vertical?
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How do I ensure precision in the pure vertical?
Look out the side to make sure you're at right angles to the horizon, hit shift-X, see how much alt the plane regains before it runs out of speed and stalls.
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I can't see any perfect way. I'd work it out so I was doing some arbitrary speed at the start of measurement (say 400mph), and then auto-angle. You'd have to have the same angle everytime and exact vertical might not work with auto-angle, since IIRC it acts funny near the vertical. But if you found some tell-tale like when the chase view mode (F4) camera starts to roll to keep its position relative to the plane as you near exact vertical, then you could set the angle to a near enough value for all planes.
The flaws are, first, that this is pretty inaccurate but IMO still at least a little useful. Second, on some planes the auto-level fails pretty bad. On a few planes it fails much earlier than the rest.. e.g. the very torquey ones. SpitXIV, K4, etc. But I think the data would still be worth having despite its low resolution.
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Stoney,
Here is an easy way to fly pure vertical......set the time for noon and point the pipper towards the sun. I think you can turn the brightness down in the arena settings. Worse case set it for midnight and use the moon as a refrence. Use the G-meter to control rate of pitch up and climb angle. If you want 70 (or ?) degrees set the time so the sun is where you want it.
Edit:Just changing the sun color to blue makes a nice target for a vertical zoom.
<S> Strip
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on a side note : autoclimb default speed changes with the planes
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Here's how I measure zoom climbs:
Dive the aircraft to ~50' asl, engage auto-level. When the airspeed drops to 400mph ias, I engage climb-on-speed set to 100mph. Once the maximum pitch is attained (about 80 degrees), I engage auto-climb-on-angle. Record maxiumum altitude achieved.
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The auto pilot will respond differently on all planes.
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The auto pilot will respond differently on all planes.
Hitech,
just the auto-pilot Level? or all the auto pilot features ? X = autopilot level, Alt X = autopilot climb, Shift X = autopilot angle
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How would you know you had a precise pitch angle? We don't have any instrumentation in the cockpit to know what pitch angle we're using--it would simply be a swag.
You might try this.
Get a piece of string and put a piece of tape at both ends – you are going to use this as a calibration line across your monitor for aligning the horizon.
Use an AH map with ocean and set the arena parameters for clear visibility to the horizon.
Up a plane, level out at 3,000 ft or so, and set auto pilot for level flight.
Go to F3 (outside view) and then go to side view of the plane (4 or 6 on the keypad) so that you can see the horizon. Probably best to find a small weight to put on the key to hold it down so you don't have to.
Open the clipboard – E6B – size it and move it so you can still see the horizon.
Reach the speed you want to run for your tests.
Pull back on your stick till you get an angle you like, set auto pilot angle to hold the angle and keep wings level. Quickly tape the line so that it lays on the horizon.
Now you have your calibration line for angle of climb.
When testing planes with superior climb the horizon line on screen will drop a little because of altitude, so it's important to get the angle set quickly at the start.
Monitor E6B for speed. When the plane decreases to a certain speed, say 140, press F1 to hop back in the cockpit, level out and check your alt.
Best.
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Hitech,
just the auto-pilot Level? or all the auto pilot features ? X = autopilot level, Alt X = autopilot climb, Shift X = autopilot angle
All of them.
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I have a very simple visual test control... Offline, I make sure the time is 12 noon (lock the time, if not already so). I take off, accelerate to a specific speed. As I attained that speed, I pull the nose vertical (3g) until the sun is in my windshield. I keep it there as long as possible. When no longer possible, I state such for the film. Do that for all aircraft and you have a reasonable standard for comparison.
My regards,
Widewing
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I mention that earlier widewing....it does a respectable job. Changing sun color takes away most of the corona effect.
Strip
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This is the test methodology I'm currently working on. It seems to be a pretty consistent methodology so far, however it's not a true "unloaded" zoom climb.
1.) take off with 50% fuel and lightest internal gun package (film on auto start)
2.) level at 500 feet and accelerate to maximum military speed (zero climb on the E6B) (I use CT and auto pilot to ensure the correct altitude to less than +/- 20 feet)
3.) set auto speed to 100 (lowest speed allowed)
4.) as soon as I reach max speed (E6B climb = zero) note max speed (TAS & IAS)
5.) then engage auto speed (with and with out WEP)
6.) observe climb and E6B during climb
7.) test is complete once IAS drops to 100, save film for later review
so as a comparison of my first few tests here are the numbers for the Me262 and the P-38L
Me 262
Initial TAS: 521mph
Initial Alt: 500 feet (exactly from the film viewer :) I'll never get that lucky again )
Max G: 2.4
Climb Time: 42 seconds
Max Alt: 10,670 feet
Zoom Alt: 10,170 feet
Zoom FPS: 242.14 feet per second
Zoom FPS / Initial TAS: .464765560 FPS/PMPH
P-38L (WEP on climb)
Initial TAS: 334mph
Initial Alt: 505 feet
Max G: 2.6
Climb Time: 25 seconds
Max Alt: 5,005 feet
Zoom Alt: 4,500 feet
Zoom FPS: 180 feet per second
Zoom FPS / Initial TAS: .538922156 FPS/PMPH
So while the 262 climbs higher, the P-38L actually is more efficient in the climb test.
You guys are much smarter than me, so I'm sure you'll come up with a better test methodology that's repeatable.
:salute Baumer (Jr. test pilot)
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Baumer thats actually a pretty good methodology and its quite interesting. By that test CoAlt-CoE the P-38 would out zoom a 262. To me this is the most useful information. Knowing who will fall out the sky first is a great bit of knowledge when deciding whether to go vertical.
Strip
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Sorry about talking about competing game but I made last year some dive and zoom testing on Il-2 using a app called Autopilot by LesniHU. It had a command to fly at constant pitch but I found out that using speed and variometer data it was possible to determine angle of the flight path. This worked out beautifully once the plane was settled to the steady climb or dive and I told about that to LesniHU. Within couple weeks he had implemented the idea to the Autopilot and testing was quite simple after that. The results are not important but picture below gives an idea about the paths on 20deg dive and zoom. There is also undocumented command for constant g pullout but I have not really tested it yet.
(http://img76.imageshack.us/img76/4585/divez.jpg)
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Id love to fly the last two in AH.... :(
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How would you know you had a precise pitch angle? We don't have any instrumentation in the cockpit to know what pitch angle we're using--it would simply be a swag.
artificial horizon is in every plane{I think} ussually displays 30 dergrees and 60 degrees....
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I'm with widewing, .time 12 0 0 sets the time to high noon and locks it.
Pull from a given set speed, put the sun in your gunsight. Different planes are going to need different exit speeds.
Tiffy is going to need more than the D3a1. So note the exit speed you pulled out at and final alt.
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This is the test methodology I'm currently working on. It seems to be a pretty consistent methodology so far, however it's not a true "unloaded" zoom climb.
so as a comparison of my first few tests here are the numbers for the Me262 and the P-38L
Me 262
Initial TAS: 521mph
Initial Alt: 500 feet (exactly from the film viewer :) I'll never get that lucky again )
Max G: 2.4
Climb Time: 42 seconds
Max Alt: 10,670 feet
Zoom Alt: 10,170 feet
Zoom FPS: 242.14 feet per second
Zoom FPS / Initial TAS: .464765560 FPS/PMPH
P-38L (WEP on climb)
Initial TAS: 334mph
Initial Alt: 505 feet
Max G: 2.6
Climb Time: 25 seconds
Max Alt: 5,005 feet
Zoom Alt: 4,500 feet
Zoom FPS: 180 feet per second
Zoom FPS / Initial TAS: .538922156 FPS/PMPH
So while the 262 climbs higher, the P-38L actually is more efficient in the climb test.
You guys are much smarter than me, so I'm sure you'll come up with a better test methodology that's repeatable.
:salute Baumer (Jr. test pilot)
Using the "sun in the windshield" test, I find that the Me 262 has miserable zoom climb ability. I set a base line speed of 344 mph, that being the max speed of a P-38L at 50 feet ASL. I tested by pulling into a pure vertical climb at 4g, keeping the sun in the windshield as long as possible, but also noting where vertical speed became zero.
All test samples were either dived to speed or, in the case of the 262, P-51D and Yak-9U, were allowed to accelerate to speed (to make sure max thrust was available).
I tested a Me 262 with full fuel, P-38L with full fuel and an A-20G with full fuel.
Takeoff Weight (zero fuel burn) were:
Me 262: 15,685 lb
P-38L: 17,700 lb
A-20G: 22,000 lb (18,738 lb @ 25% fuel)
Rounded to nearest 50 foot increment, peak altitudes starting at 344 mph from 50 ft ASL were:
Me 262: 3,600 ft
P-38L: 4,350 ft
A-20: 4,200 ft (dropping fuel to 25%, the A-20 managed 4,350 ft)
For reference, I also tested two other fully fueled fighters, but didn't record weights.
P-51D: 4,300 ft
Yak-9U: 4,400 ft
Repeating the test using auto-climb typically resulted in far less altitude gained, with the 262 most adversely effected.
I prefer pure vertical zoom testing for one simple reason: It better defines what you will encounter in a fight. It also demonstrates why trying to escape a Co-E A-20 in the vertical is futile. Likewise, it shows why a low and slow Me 262 is usually dead in short order.
My regards,
Widewing
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Widewing did you use WEP during your tests? I assume you must have, to get 344mph with the P-38L I was just wondering.
The reason I choose to perform my test at max speed (no WEP) was to achieve a consistent result for all aircraft. In my opinion, by selecting an arbitrary airspeed it changes the premises of the original question. By running the test at the assigned speed, you are in essence comparing an aircraft at it's maximum E state (P-38L) to one that's only at 64% of it's potential E state (Me 262).
However, I do see the value of this kind of testing it equate it to "real world" situations. But, there needs to a much more comprehensive set of tests done at various speeds to best understand an aircraft's zoom potential.
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But, there needs to a much more comprehensive set of tests done at various speeds to best understand an aircraft's zoom potential.
Absolutely..
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Hmmm...the 262 test surprises me. I thought a 262 was a couple of rather low thrust jet engines strapped to a slick airframe. I had assumed the mass/drag ratio would be quite high. Hmmmm...
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Widewing did you use WEP during your tests? I assume you must have, to get 344mph with the P-38L I was just wondering.
The reason I choose to perform my test at max speed (no WEP) was to achieve a consistent result for all aircraft. In my opinion, by selecting an arbitrary airspeed it changes the premises of the original question. By running the test at the assigned speed, you are in essence comparing an aircraft at it's maximum E state (P-38L) to one that's only at 64% of it's potential E state (Me 262).
However, I do see the value of this kind of testing it equate it to "real world" situations. But, there needs to a much more comprehensive set of tests done at various speeds to best understand an aircraft's zoom potential.
Real world data is considerably more useful to the average AH2 pilot than data taken using scientific method.
The problem with scientific data is that it is meaningless in the fluid, constantly changing realm of combat. This is especially true for zoom climb. Zoom climb is always related to E state. A Zero will run down a somewhat slower flying 109K-4 in a vertical climb. Zoom climb can vary based upon weight and based upon induced drag. It depends on many circumstances that will change from minute to minute, even second to second. A straight zoom climb is not a safe tactic unless the relative E states are vastly different. Indeed, I have killed many a fast fighter that I forced into an overshoot, but who simply flew by in a straight climb. The E state of bullets is always superior.
Scientific data is interesting, but reference knowledge is more practical in combat. Who would guess that a twin-engine medium bomber could easily run down a Co-E 262 in a vertical zoom? Likewise, there is little difference between a Ta 152 and the 262 when both start at 520 mph. indeed, there is not much difference between most fighters if they begin at equal E states.
In a fight, few aircraft will be anywhere near maximum speed. Those that are, are not really in a fight, per se. In a fight, the knowledge of the ability of any aircraft to transfer E into vertical displacement at relatively low E states is far more valuable than knowing how far up it can zoom at maximum level speed. Excluding the minor variances associated with mass and drag, the ultimate determining factor in zoom climb height is E state. Another factor significant to jets is available thrust. Early jets had relatively low thrust powerplants. At 100 mph, the Spit14 has far greater thrust than the Me 262. At 400 mph, this is reversed and the prop is now a major source of drag. This is one reason why the Spit accelerates so much faster than the 262 at low speeds (the other obviously being weight). If you map the zoom climb of the Ta 152 and 262 as I tested them, you will see something interesting.
Initially, the 152 decelerates faster than the 262. As speeds decrease, the rate of deceleration equalizes, with the 262 decelerating faster than the 152 as speeds approach 100 mph. The 262 pulls out a 400 yard lead, but as speeds drop, the 152 cuts that in half. This is due to the 152 having much less thrust at the beginning, but more thrust nearing the apogee of the climb.
My regards,
Widewing
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How could you best illustrate all this data? I'm thinking bar graphs like the ones on Gonzo(?)'s, but animated. Each graph with a different initial speed. The bars grow in real time or by a standard multiplier, up to an annotated peak.
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I agree that practical data is more useful to most players of Aces High, the same argument can be said for the turning data that's presented in the other performance tools and references. I have spent several hours flying as directed by badboys bootstrap calculator. And to equate those data points to the actual combat experience is just as complicated. btw, thank you all so much for doing all that test flying. It's very tedious and demanding to get that data, so a big <S> to badboy, murdr, widewing and anyone else contributed to all that data.
Just as a comparison, I re-ran my P-38L test incorporating your configuration and this is the data from an auto-speed test. Once I reach max airspeed I initiated an auto-speed climb and engaged WEP.
P-38L
Weight: 17,700lb
Fuel Burn Rate: 0.001
Initial TAS: 331mph
Initial Altitude: 61 feet
Max G: 2.8G
100mph IAS Altitude:4,305 feet
TAS at top of Zoom: 110mph
Zoom FPS:163.23 feet
Time of Zoom: 26 Seconds
So our testing yielded very similar results in max altitude with about a 50 foot difference, with you at Zero IAS and me at 100mph IAS. And interesting note, once the P-38 hit 100mph IAS it settled into an oscillating climb varying from 500 to 3000 fpm on the VSI. I assume that you reached your max altitude more quickly than I did, so that's probably another difference.
Thanks for the feedback Widewing, it's an interesting topic for sure.