quote:

Originally posted by AKA_TAGERT:
The 109K-4 is the king of zoom..

Thanks for posting your test results!

One question remains tho...

Did you fill up all those fighters with 100% fuel and default armament?
I assume you did...

However...

In reality, online people tend to use 50% or in some cases 25% fuel in let's say - P-51D.
I fought 6 JAAF fighters for over 55mins and RTB'ed with 50% fuel on P-51D. There was a lot of 110%+Water Meth injection used...

If we take into consideration that you need 100% fuel in Bf-109K4 for such feature, conclusion is clear...

So while I have no reason to doubt your test results, i.e. I believe them, just this fuel issue should be considered too.

How having a considerably heavier fighter can impact overall performance and thus impact your field performance is not really doubtful.

quote:

IRL Zoom does not suddenly stop, it is a gradual process, the prop helping it along until gradually the prop takes over all togther and you are into powered climb.

It is impossible to determine without the engine at idle and prop feathered. But at the very least the tests should look only at the part of the climb in which the speed is somewhat greater than best climb speed, and be started at the same initial velocity. If Tagert had started the tests all at the same speed and plotted speed versus altitude then it would be easier to measure zoom climb. As it is his data measures a combination, muddled together, of dive performance, zoom, and sustained climb with not enough data to determine zoom.

quote:

So while I have no reason to doubt your test results, i.e. I believe them, just this fuel issue should be considered too.

I have NO* doubt that they accurately tested what they tested, but they did not test zoom climb in isolation and on an equivalent basis that allows the graphs to be used to compare zoom climb performance.

If Tagert reapeated them at the same initial high speed at the bottom of the climb then it would give a decent picture, with engine flat out, it would give a reasonable indication of what you could expect in real life as zoom begins to morph into sustained. If doing this, given that power varies with altitude you'd really want to test at some representative heighs (SL, 5000ft, 10000ft, 20000ft perhaps) and maybe a range of initial speeds, e.g. 300, 350, and 400 TAS where the planes can handle it.

Doing this would probably give a picture more similar to the AFDU and other results, e.g Tempest and Mustang doing well, 109 less so, but better than the Spitfire.

* misstyped this originally - now corrected!

without question..

In the game don't forget the P-63 It can follow an Me262 on a climb

Sustained climb, not ure about zoom.

quote:

Originally posted by cawimmer430:

How would you know you Mitsubishi Zero rice burner..?

quote:

Originally posted by Aaron_GT:
Doing this would probably give a picture more similar to the AFDU and other results, e.g Tempest and Mustang doing well, 109 less so, but better than the Spitfire.

Mustang III COMBAT TRIALS AGAINST Me.109G

Zoom Climb
... Unfortunately the Me. 109G appears to have a very good high-speed climb, making the aircraft very similar in a zoom climb.

Tempest V COMBAT TRIALS AGAINST Me.109G

... The Tempest is only slightly better in a zoom climb if the two aircraft start at the same speed, but if the Tempest has an initial advantage, it will hold this advantage easily providing the speed is kept over 250 mph.

Note : Tested against Bf 109G-2/trop captured damaged in the desert in late 1942.

Bf 109K-4 'C-3' (i.e. 2000 PS engine) has 700 HP more and is heavier by 300 kg than the G-2/trop tested there, and has cleaner airframe. Obviously its zoom climb properties are much better than those of the 109G-2.

So I don`t quite get the whining about it.

In a zoom climb in WWII prop fighters second for second and no funny BS misdirection pulled
the faster one going upwards by more than a miniscule margin will zoom higher.

If all planes start the zoom at the same speed then it's a matter of excess power throughout
the zoom.

Importance of start speed is a second order, ie squared, factor in ending height where all
other factors are first order only. That has been shown here more than once.

If you want to play tricks then you can exaggerate the H out of one plane over another when
in the pure combat zoom it does not. But it takes tricks.

Historic tests ran planes starting side by side and took end measurements both at the same time.

quote:

Originally posted by Kurfurst__:

quote:

Originally posted by Aaron_GT:
Doing this would probably give a picture more similar to the AFDU and other results, e.g Tempest and Mustang doing well, 109 less so, but better than the Spitfire.

Mustang III COMBAT TRIALS AGAINST Me.109G

Zoom Climb
... Unfortunately the Me. 109G appears to have a very good high-speed climb, making the aircraft very similar in a zoom climb.

Tempest V COMBAT TRIALS AGAINST Me.109G

... The Tempest is only slightly better in a zoom climb if the two aircraft start at the same speed, but if the Tempest has an initial advantage, it will hold this advantage easily providing the speed is kept over 250 mph.

Note : Tested against Bf 109G-2/trop captured damaged in the desert in late 1942.

Bf 109K-4 'C-3' (i.e. 2000 PS engine) has 700 HP more and is heavier by 300 kg than the G-2/trop tested there, and has cleaner airframe. Obviously its zoom climb properties are much better than those of the 109G-2.

So I don`t quite get the whining about it.

Thank you for the reality. Is the full report on the net and can it be linked to?
I would like to see if the tropical model 109G-2 had filters in place, etc, during those.

quote:

Originally posted by Aaron_GT:
If Tagert reapeated them at the same initial high speed at the bottom of the climb then it would give a decent picture, with engine flat out, it would give a reasonable indication of what you could expect in real life as zoom begins to morph into sustained. If doing this, given that power varies with altitude you'd really want to test at some representative heighs (SL, 5000ft, 10000ft, 20000ft perhaps) and maybe a range of initial speeds, e.g. 300, 350, and 400 TAS where the planes can handle it.

I kinda agree to this, especially regarding same speed at the beginning of the zoom.

I still respect Tagert's testing because I know what kind of PiTA testing (a lot of aircraft) can be.

quote:

Originally posted by stalkervision:
without question..
http://www.zap16.com/Me%20163/luftw06-me163-191904-2.jpg

Wouldn't be 100% sure...

We have two Bi-6 variants for engine sustained climb...

quote:

Originally posted by Aaron_GT:
Sustained climb, not ure about zoom.

+1

I was a bit harsh on Tagert. You are right, Dkoor, his testing is excellent and I baulk at trying to replicate the climb portions from given start speeds.

Kurfurst is also correct that the 109G used in the testing might have been the 109G2, although whether it was that or a G6 always seems to be a matter of debate.

M_Gunz is also correct in that engine power may well be more of a factor than I considered in my too hasty initial replies.

More bits from the Tempest AFDU report (note that all we have is not apparently a final production aircraft, but is at combat weight, but is several hundred hp short of production types depending on engine and boost, by 20% or possibly more).

Versus Mustang III (unknown boost)
"At similar performance height the Tempest has a better zoom climb. "

Against Spitfire XIV:
"Maximum Climb
33. The Tempest is not in the same class as the Spitfire XIV. The Tempest V however, has a considerably better zoom climb, holding a higher speed throughout the manoeuvre. If the climb is prolonged until climbing speed is reached, then, of course the Spitfire XIV will begin to catch and pull ahead. "

Which is important as it shows the distinction between zoom and sustained best climb rate (which is the usually quoted ROC figure).

Versus 190A:
"Except below 5,000 feet the FW.190 (BMW.801D) has a slightly better maximum rate of climb. . Because of the Tempest V's speed and clean lines however, the Tempest has a markedly better zoom climb, where the speed is kept high. "

Versus 109G
"The Tempest is behind the Me.109G at all heights, but being almost similar below 5,000 feet. The Tempest is only slightly better in a zoom climb if the two aircraft start at the same speed, but if the Tempest has an initial advantage, it will hold this advantage easily providing the speed is kept over 250 mph. "

Again in these two you see the distinction between sustained (Tempest less good) and zoom (Tempest better), showing that sustained ROC is not a guide to zoom.

In terms of combat usefullness zoom at the same speed is a useful comparison as it shows you whether, if you are on the 6 of a plane at high level speed and it decides to do a zoom climb whether it is worth trying to follow.

The 262 actually has good sustained climb rate, but the climb speed is high. Climb at a prop climb speed of 150 +- 50 mph and the climb rate is poor and the engine overheats! At 4000 ft/min it is behind some of the best ww2 prop planes, but at much higher horizontal speed a prop plane won't catch one at best climb speeds in a chase even with the highest ww2 prop sustained ROCs of around 4500 ft/min (e.g f4u-4 at 4770)

quote:

Originally posted by Xiolablu3:
I thik what Tagert is talking about is 'Zoom' in the real world rather than theoretical Zoom.

IRL Zoom does not suddenly stop, it is a gradual process, the prop helping it along until gradually the prop takes over all togther and you are into powered climb.

That's got nothing to do with "real" and "theoretical" zoom climbs.

Tagert test is combination of dive, pullout and zoom climb. All of these elements contribute to final result.Plane with best result is not necessarily best in any of individual categories.

Beside that test have fundamental error due to limitations in Autopilot utility. During test planes were flown at constant pitch but when you fly two different planes at constant pitch angle than you end up with different flight paths.

As dive and climb performance are directly dependent on dive and climb angle than it's obvious that planes didn't performed test at same conditions.

It same as comparing one plane flying with engine on idle and another at full power.

This can be easily seen in charts where worser diving planes dive steeper and thus get more help from gravity and than climb at shallower angle and are less affected by gravity than heavier planes.

Anyway, you can make zoom test to suit any agenda you might have if you play with climb angle and entry speed.

FC

The two 109Gs used in the AFDU tactrials were Bf 109G-2/trop 'Black Six', designated RN-something (221 IIRC) and Bf 109G-6/U2 with Rüstsatz III and VI (and droptank and gondolas). The G-6/U2 was however not used in AFDU trials against the Tempest, the brits crashed it so earlier trials with the G-2/trop were used in the report.

I have no idea what power output they used during the test (ie. 1,3ata 30-min or 1,42ata 5-min). Neither at which altitudes the tests were done. Generally the problem with the AFDU trials is that they are very unprofessional, and vague when it comes to details. Other trials I have seen, inc. earlier British tests are much more specific.

The Tempest in the trials appears to be a fully powered version. 'It is fitted with a Napier Sabre II engine of approximately 2090 h.p. (same as Typhoon IB)., though of course given the date (February 1944) its a Sabre IIA version. Its nothing to complain about, given the higher powered Sabre IIB did not appear until late 1944.

Xiolablu3, I have thought of doing the test again and shutting off the engine or turning throttle to 0 (I figure the planes that can feather props might have an advantage, maybe drag issue of shutting them completley off?) and see how much the results differ.. Maybe the P-47 would show better with a powerless zoom climb from close to max aircraft speed, or.. Maybe a lighter plane that doesn't have all that much horespower might do better? Not really a real world application as I believe you stated, but it might be a good way of knowing what parts of the aircraft are playing bigger factors into its performance.

quote:

Generally the problem with the AFDU trials is that they are very unprofessional, and vague when it comes to details. Other trials I have seen, inc. earlier British tests are much more specific.

This is very true.

quote:

The Tempest in the trials appears to be a fully powered version. 'It is fitted with a Napier Sabre II engine of approximately 2090 h.p. (same as Typhoon IB).,

The aircraft in the tests is JN.731, and the performance trials in April 1944 indicate that it could not manage the standard IIA boost of +9, but only +8.5. It was not fully powered. In the performance tests allowances had to be calculated to correct to +9lbs. If it was a IIA at +9 it should have been getting 90hp more than recorded (i.e 2180)

Later in the war the IIB managed 2420hp at +11 boost, and +13 use is attested to on squadron level by eye witnesses, givig more than 2420. I am not entirely convinced by Closterman's suggestions of 3000hp, although Napier did get a similar design to 5500hp on the bench.

quote:

Originally posted by Stiletto-:
Xiolablu3, I have thought of doing the test again and shutting off the engine or turning throttle to 0 (I figure the planes that can feather props might have an advantage, maybe drag issue of shutting them completley off?) and see how much the results differ.. Maybe the P-47 would show better with a powerless zoom climb from close to max aircraft speed, or.. Maybe a lighter plane that doesn't have all that much horespower might do better? Not really a real world application as I believe you stated, but it might be a good way of knowing what parts of the aircraft are playing bigger factors into its performance.

I'm not sure what this would tell you that common sense won't. Planes with more mass will zoom higher in the above scenario (given the same starting speed).

quote:

Originally posted by FatCat_99:

quote:

Originally posted by Xiolablu3:
I thik what Tagert is talking about is 'Zoom' in the real world rather than theoretical Zoom.

IRL Zoom does not suddenly stop, it is a gradual process, the prop helping it along until gradually the prop takes over all togther and you are into powered climb.

That's got nothing to do with "real" and "theoretical" zoom climbs.

Tagert test is combination of dive, pullout and zoom climb. All of these elements contribute to final result.Plane with best result is not necessarily best in any of individual categories.

He's not testing zoom climb. Those graphs assess the ability of each aircraft to convert potential energy to kinetic energy and back.