Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: funked on February 29, 2000, 07:45:00 PM
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Shouldn't the engine cut out under negative gees?
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Hummm, I thought it was a problem only for early Marks. Should be interesting to know wich MkV we have here now.
Some late war MkV's were real demons. Fd? (http://bbs.hitechcreations.com/smf/Smileys/default/wink.gif)
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I think it should. Even many early IX's did not have the negative G carb, let alone V's. I guess late war V's with clipped wings did have same carbs as the IX's so they should not cut under neg G's. But I think our V is early war V because of colour scheme and it engine should indeed cut under neg G.
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jochen
Geschwaderkommodore
Jagdgeschwader 2 'Richthofen' (http://personal.inet.fi/cool/jan.nousiainen/JG2) (Warbirds)
jochen
JG 2 'Richthofen' (Aces High)
If you ever get across the sea to England,
Then maybe at the closing of the day
The bars will all be serving German lager
Which means we won the war - hip hip hooray!
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Gatt, good point. I know there were V's serving until late in the war, some with modifications to improve performance. Maybe the neg-g carb kit was part of it?
[This message has been edited by funked (edited 03-01-2000).]
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I don't remember the details of top of my head, but i think the solution to this problem was NOT a neg-G carborator...
The fuel flow valve was modified in late Mk I's in such a fashion that it alliviated the cut-off problem ... something about simple but ingenious modification...
I'll see if i can find more details.
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(http://www.raf303.org/banner.gif)
Bartlomiej Rajewski
S/L fd-ski Sq. 303 (Polish) "Kosciuszko" RAF
www.raf303.org (http://www.raf303.org)
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A woman called Schilling at the RAE devised a small diaphram to fit in the carb that prevented cut-out in negative G manouevers. This was developed during the BOB so all later Spits should have at least this protection against cut out. Later Spits had better pressurised carbs, iirc.
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They still cut out though. I think Packard really fixed it when they started making the engines under license.
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Depends on the time-frame of the Spit V. Dec 41 is when they ordered retrofits of the carb mods to the MK V.
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Doug "Pyro" Balmos
HiTech Creations
"If it's stupid but works, it's not stupid."
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Hehee key word is "ordered". I "ordered" some pizza at the 99 WB Con and I still haven't received it. (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
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Funked, are you talking about Pizzaware 3.0?
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Juzz,
the Mk V should not have the neg-G cut out. A few did, but the vast majority were fuel injected. The first Spitfire to use the Packard Merlin was the Mk XVI, which I have read nothing particularly good about and was not introduced until after the Griffon equipped Mk XIV. Only the Mk I and Mk II should be affected by the float carbarater.
Sisu
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Here's what I meant: The AFDU report on the Fw 190A-3 written in summer 1942 mentions that both the Spitfire V and IX were having trouble in combat with engine cutout under negative gees. So whatever mods had been ordered in 1941 had obviously not been carried out by mid-1942.
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The problem with ADFU reports is that they usually recieved pre-production British planes for tests. Just because the plane they were using didn't have it doesn't mean it wasn't standard fit.
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It does if you're a LW weenie like Funked. (http://bbs.hitechcreations.com/smf/Smileys/default/wink.gif)
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SnakeEyes
o-o-o-
=4th Fighter Group=
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Nashwan - good point. However they weren't just referring to their test article, they were referring to planes in service as well.
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[This message has been edited by funked (edited 03-08-2000).]
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SnakeEyes, by your logic I would conclude that all Fw 190A-3's had derated engines with sparkplug problems. (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
Not a Luftwaffe weenie, just obsessed with accuracy.
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Aces High Instructor Corps
303 (Polish) Squadron "City of Cracow"
[This message has been edited by funked (edited 03-08-2000).]
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Agreed... as long as you assume that Pyro is modeling the Spit Vs that didn't have the injection. (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
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SnakeEyes
o-o-o-
=4th Fighter Group=
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Hang on, I misread something.
The complaints I've read were only about a Spitfire Mk. IX. The AFDU report does not describe negative-g problems with the Mk. Vb. Sholto Douglas' cover letter states that he has only 14 Spitfire IX at the time (7/17/42) and that none of them have negative-g carburation. That's all I've got.
P.S.
I don't believe that any of the Merlins in the V or IX had fuel injection in the true sense. It was an injection carburetor aka "throttle body injection". Not true port fuel injection like on a BMW 801.
[This message has been edited by funked (edited 03-08-2000).]
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And do not forget that since we have a 1944 plane set, any Mk V planes still in service at that point would definitly have the neccesary refits :P
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I'm simply assuming that, because this issue has been widely discussed for some time (since the WB 1.11 days at least), Pyro is certainly aware, and has decided to model the later models where the issue was resolved.
Given the planeset in AH, that at least makes plenty of sense from a playbalance perspective (combine the realism approach with playbalance by modeling a later variant).
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SnakeEyes
o-o-o-
=4th Fighter Group=
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Yep this thread should be closed, because I misread the UK document. I have no evidence of such a problem with the Spitfire Mk. V.
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I have read that the modified "Schilling" carb still didn't totally prevent negative-g cutout. But obviously Packard fixed it - has anyone ever heard any mention of negative-g cutout problems with the Mustang?
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negative, only early mkV planes had problems with it, and mostly from premature failure in designs from engineers in britain. Once the packard system was introduced the negative G issue never came up again. However, to tell the truth all mkV planes should have cut-out under more than -6 or -7G. This was approximatly the same amount of pressure upwards as the blower was forcing downwards and would result in flooding or lean out in the fuel. This was noted in several test flights done by the RAF against 109's. I think it's not modelled because it is really irrelevant. The odds of it happening are to rare and extreme to really worry about it not being there.
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If your in range, so is the enemy.
(http://www3.bc.sympatico.ca/sorrow/sorrow.gif)
[This message has been edited by Sorrow[S=A] (edited 03-09-2000).]
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Juzz, the Schilling modification was a fix that could be applied to the early engines, but RR did design a neg G carb that was fitted on later engines.
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Another perhaps more significant difference between the fuel injected 109 engines and the Merlin's carburetors was the throttle management. I have an older book that details some flight testing on a captured 109E vs. an early spit. One of the first things that is noted on the 109 is the ability to virtually slam the throttle to any position with instantaneous results. This was not so with the spit without a significant amount of coughing and sputtering.
Also how about changing the Mk. VB we have now to a Mk. VC. The C had 4 cannons instead of 4x.303 and 2x20mm. Taken together the Mk. V series were produced in greater numbers than any other variant and a full 10% of that number were C versions. My gunnery skills are so bad that I really need big guns (http://bbs.hitechcreations.com/smf/Smileys/default/tongue.gif)
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... and another quote from my dear old dad, ex 124 RAF Spit VII's etc ...
" ... it was known universally throughout the RAF as 'Miss Schilling's orifice' ... "
<grin>
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skeet - out
Aces High - Fight Stimulator
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Spirtle
The Vc could carry 4 20mm, so it would be an interesting load out option for an allied plane. The IX had the same capability though so if HTC was inclined to allow that (quite rare) load out, they could do so now.
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Pongo
The Wrecking Crew
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The spit V in AH is painted in 1941 colours. It should have a 1941 engine and a 1941 carb.
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Pongo
The Wrecking Crew
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Pongo,
I just picked the VC because there were probably more VC's than IX's with a 4x20mm load out. I could be wrong on that though.
Spritle
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I think you are correct. One of my books says that the only 4 cannon IXs were converted Vc airframes. But this is a Vc they are modeling here despite the Vb paint job. It has the ammo load of a Vc.
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Pongo
The Wrecking Crew
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Our paint jobs are chosen to match the variant of the actual plane modeled as well as providing something that is both interesting and different from other similar planes. Matching an exact sub-variant is not a part of our criteria. We are not going to model every sub-variant and paint scheme. The paint schemes of the P-38L and P-51D should preclude them from carrying rockets, but we're not worried about that.
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Doug "Pyro" Balmos
HiTech Creations
No sniveling!
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I just read a quote by Pierre Closterman (in Warplanes of the Third Reich by Wm. Green) where he describes engine cut-out problems while chasing a Bf 109G through negative-G maneuvers in a Spitfire Mk. V. The G model Messerschmitt was not in combat until the summer of 1942.
So whatever the orders were, the modifications had obviously not been uniformly carried out by mid 1942.
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Mike "FunkedUp" Waltz
Aces High Instructor Corps
Squadron Leader, 308 (Polish) Squadron "City of Cracow" RAF
(http://www.raf303.org/308/308logo.GIF)
[This message has been edited by funked (edited 03-17-2000).]
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What it really comes down to is this: most Spit Vs and IXs did not suffer from the neg-G cutout. Since individual aircraft are not modeled, and random problems/failures are not modeled it is best to model the fuel injected versions of the Spit. The Brits are already flying '41 and '42 tech, why handicap us even more?
Sisu
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Originally posted by Pyro:
Our paint jobs are chosen to match the variant of the actual plane modeled as well as providing something that is both interesting and different from other similar planes. Matching an exact sub-variant is not a part of our criteria. We are not going to model every sub-variant and paint scheme. The paint schemes of the P-38L and P-51D should preclude them from carrying rockets, but we're not worried about that.
Thats no prob with me..
"We wanted a distinctive paint scheme on the V vs the IX but we wanted to show a late production capable V in thsi plane set. So we combined the performance of a late Vc with the paint from an early Vb...Its our game. sue us."
(http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
Although the AS engined Bf109g6 would also fill your criteria quite well.
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Pongo
The Wrecking Crew
[This message has been edited by Pongo (edited 03-20-2000).]
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You know a 308 Squadron paint job on the Spitfire Mk. V would be nice. (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
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Getting a bit cocky aren't we? (http://bbs.hitechcreations.com/smf/Smileys/default/wink.gif)
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Hehehe!
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Originally posted by funked:
You know a 308 Squadron paint job on the Spitfire Mk. V would be nice. (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
Hey!!! I like the London Butcher (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif) (at least that's my opinion on what spit5 modeled in AH - see my other thread)
In regard of cut out. It was fixed in early production models of Spit5. Planes produced before that, were later fitted with a new system too. So I guess it is correct that we don't have neg G engine cut out.
mx22
[This message has been edited by mx22 (edited 03-24-2000).]
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Really...I like Pyros reason better. It makes more sense.
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Pongo
The Wrecking Crew