Spitfire engine failure in dive?
- Thread starter Major
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ccheese
Member In Perpetuity
One of the Brits may be able to help you, Major....
But, I'll welcome you to the forum....
Charles
But, I'll welcome you to the forum....
Charles
- Thread starter
- #3
It was the engine on the early marks of Spitfires. Had a standard, gravity fed carb. Would cut out in negative g. Brits fixed it with a "floating" carb. Seemed to do the trick.
Germans 109s used a fuel pump. My understanding is it was in the gas tank itself. Pretty smart engineering, if accurate.
Germans 109s used a fuel pump. My understanding is it was in the gas tank itself. Pretty smart engineering, if accurate.
- Thread starter
- #5
claidemore
Senior Airman
Not sure that "engine failure" would be the correct term to describe that phenomenon, usually it resulted in the engine sputtering and coughing as a result of reduced fuel flow, rather than complete fuel starvation. Pilot had to hold negative G for an uncomfortable length of time to cut the engine out completely and it would roar back to life as soon as they returned to positive G flight.
Starting during the production of the Mk V they used a modified carburator, designed by a female engineer, that was referred to as "Miss Shillings orifice". This partly fixed the problem.
The Bendix-Stromberg carburater in the Mk IX was the final solution and eliminated the problem completely.
The DB engines on the Messerschmitts were fuel injected.
Starting during the production of the Mk V they used a modified carburator, designed by a female engineer, that was referred to as "Miss Shillings orifice". This partly fixed the problem.
The Bendix-Stromberg carburater in the Mk IX was the final solution and eliminated the problem completely.
The DB engines on the Messerschmitts were fuel injected.
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- #7
claidemore
Senior Airman
They used the modified carbs (shillings orifice) on the Mk V's, the Bendix-Stromberg carbs came on the Mk IXs. I believe the B-S carbs (lol) were retro-fitted on MkVs, not 100% certain on that.
Claidemore
- Thread starter
- #9
K i just read this:
The first improvement was the shilling's orifice, after that rolls royce made an improved carburetor that could take sustained negative G's (they were put into all rolls royce engines from merlin 45 on), than the final version was the bendix, which were fitted on merlin 61's and above.
correct me if im wrong
The first improvement was the shilling's orifice, after that rolls royce made an improved carburetor that could take sustained negative G's (they were put into all rolls royce engines from merlin 45 on), than the final version was the bendix, which were fitted on merlin 61's and above.
correct me if im wrong
Flyboy2
Senior Airman
Its my understanding that to counteract this problem the Spitfire pilots would split-S a dive. They would roll upside down and then dive to maintain positive G's in the dive so the engine wouldn't sputter. This is opposed to the Bf-109 which could just go right into a dive because of thier injector system.
kool kitty89
Senior Master Sergeant
I thibk this was a "pressure carburetor" like those used by the V-1710. This is basicly the same type of mechanism as "single point fuel injection" (throttle body ingection in GM terminology) which uses a pressure pump to inject fuel through a spray nozzel into the intake manifold or throttle body.
This also explains why the V-1710 (and other US engines using these carbs, including the pre war R-1820 and R-1830, never suffered from -G or inverted flight cut-out problems)
kool kitty89
Senior Master Sergeant
As long as tou kept pulling +G's you'd be fine.
One thing I've wondered about though is what about the DH. Mossie and Westland Whirlwind. With the Mossie using early Merlins and the Whirlwind using Perigrines (which should have similar carbs), wouldn't simply rolling the a/c cause an engine (the one rolling downward experiencing -G's) to sputter, or if it was a hard roll (combat maneuvering) cause the engine to cut out completely?
That would pose a serious problem, and one that contemporary German and US designs didn't have to face with all combat engines using either pressure carbs or fuel injection. (though it was carburetor fed, I think the DB 600 used a pressure carb too, which was being replaced with the direct injected 601 aniway and the Jumo 210G, 211, and BMW 801 were all direct injected as well)
The neg g problems on spit 1 and Hurri Is were two fold. Initially at the onset of neg g the fuel and float would splash to the top of the float bowl, closing the needle valve and starving the engine of fuel. If the neg Gs were sustained the heavier fuel would displace the float downwards opening the needle valve flooding the engine and could potentially lead to engine hydrolock.
The first sloution was the famous shilling orifice. introduced after the BoB, that restricted fuel flow and prevented the second problem of flooding the engine and hydro lock.
The next improvement was a baffle in the float bowl that helped prevent the fuel and float from surging upward under limited neg gs. this allowed short neg g manouevres. This was used on spit v s Hurri IIs and merlin 61 Spit 9s afaik.
Latter merlins had the stromberg injector carbs(throttle body injection) allowing sustained neg g manouevres.
Slaterat
The first sloution was the famous shilling orifice. introduced after the BoB, that restricted fuel flow and prevented the second problem of flooding the engine and hydro lock.
The next improvement was a baffle in the float bowl that helped prevent the fuel and float from surging upward under limited neg gs. this allowed short neg g manouevres. This was used on spit v s Hurri IIs and merlin 61 Spit 9s afaik.
Latter merlins had the stromberg injector carbs(throttle body injection) allowing sustained neg g manouevres.
Slaterat
- Thread starter
- #14
Hmm I wonder how long the shillings orifice allowed the spitfire to peform neg G stuff, ive searched a little and it seems that no one knows the exact amount of seconds the spitfire could peform neg G stuff without the engine sputtering.
Also, did the Rolls royce Griffon engines have this problem also?
Also, did the Rolls royce Griffon engines have this problem also?
claidemore
Senior Airman
Major;
From a Rolls Royce Griffon book, Griffon engines had the Bendix carb.
I believe you can view that document at the link below, as well as a host of other Spitfire related info. I may have downloaded it from there too.
You should also check out the Techincal Section on these forums.
Spitfire Performance Testing
From a Rolls Royce Griffon book, Griffon engines had the Bendix carb.
I believe you can view that document at the link below, as well as a host of other Spitfire related info. I may have downloaded it from there too.
You should also check out the Techincal Section on these forums.
Spitfire Performance Testing
Attachments
kool kitty89
Senior Master Sergeant
To my earlier question: Does anyone know of problems from the effects of -G from rolling (particularly hard rolling) a twin engine a/c (ie Mossie and Whirlwind) with these carburetors of early Merlins (or Perrigrines)?
And from what I've read the Schilling's orifice (and other pre injection carb improvements) was that -G could be performed for limited time periods (a few seconds, not specified but probably much less than 30 sec) and inverted flight could not be maintained for useful lengths of time.
And from what I've read the Schilling's orifice (and other pre injection carb improvements) was that -G could be performed for limited time periods (a few seconds, not specified but probably much less than 30 sec) and inverted flight could not be maintained for useful lengths of time.
- Thread starter
- #17
One of the great problems, as discerned by pilots was the tendency for the carburetted engine to cut out under negative 'g'. Luftwaffe pilots learned to escape by simply pushing the nose of their aircraft down into a dive, as their fuel- injected engines did not cut out under these circumstances. Many authors have criticised this aspect of the Merlin design. In reality, like most engineering, it resulted from a design compromise. The drop in temperature developed in a carburettor results in an increase in the density of the fuel-air mixture when compared to that of a fuel injection system. As a consequence the Merlin produced a higher specific power output (horse power per pound) than the equivalent German engine. It was felt that this gave a higher power to weight ratio for the fighter and (rightly or wrongly) that this outweighed the disadvantages. By 1941 Miss Tilly Shilling in Farnborough had developed a partial cure for the problem. A diaphragm across the float chambers with a calibrated hole (the infamous "Miss Shilling's orifice"! I think 'restrictor' is the correct term, orifice sounds like someone's rude sense of humour.) allowed negative 'g' manoeuvres, and was fitted as standard from March 1941. Fitting the new carburettor to the Merlin 45 created the Merlin 50 series. Late production Mk Vs were fitted with the Merlin 50 or 50A and 56 optimised for high altitude, or the 55 with a two-piece engine block. To optimise low-altitude performance the blades of the supercharger blowers were cropped. These engines were identified with the suffix M. For the Mk V these comprised the 45M, 50M and 55M. Sustained zero 'g' manoeuvres were not sorted out until somewhat later. In 1942 an anti-g version of the SU carburettor was fitted to single and two stage Merlins. 1943 saw the introduction of the Bendix-Stromburg carburettor which injected fuel at 5psi through a nozzle direct into the supercharger and was fitted to the Merlin 66, 70, 76, 77, and 85. The final development was the SU injection carburettor which injected fuel into the supercharger using a fuel pump driven as a function of crankshaft speed and engine pressures, which was fitted to the 100 series Merlins.
- Thread starter
- #19
wow thanks. So from what I read there are 3 versions.
1. Miss shillings orifice
2. Anti-G version of SU carburettor
3 Stromburg carburettor
Do you happen to know if rolls, split-S's, loops, and the opposite of a split-S(forgot what its called) produced negative G's or positive G's? Im pretty sure that Loops are positive but im not sure of the rest.
1. Miss shillings orifice
2. Anti-G version of SU carburettor
3 Stromburg carburettor
Do you happen to know if rolls, split-S's, loops, and the opposite of a split-S(forgot what its called) produced negative G's or positive G's? Im pretty sure that Loops are positive but im not sure of the rest.
Hi Koolkitty,
>To my earlier question: Does anyone know of problems from the effects of -G from rolling (particularly hard rolling) a twin engine a/c (ie Mossie and Whirlwind) with these carburetors of early Merlins (or Perrigrines)?
I've never heard of such problems, and I suspect that the high rotational inertia that results from the twin's engines' outboard position made it difficult to achieve roll accelerations required to create carburetion problems.
>And from what I've read the Schilling's orifice (and other pre injection carb improvements) was that -G could be performed for limited time periods (a few seconds, not specified but probably much less than 30 sec) and inverted flight could not be maintained for useful lengths of time.
From the Pilot Training Manual for the P-51 Mustang (covering the D and K variants with Merlin engines):
"However, when the plane is in inverted flight, the oil pressure falls off because no oil reaches the scavenger pump. For that reason you must limit inverted flying to 10 seconds - which is plenty of time for any normal or combat maneuvers."
Regards,
Henning (HoHun)
>To my earlier question: Does anyone know of problems from the effects of -G from rolling (particularly hard rolling) a twin engine a/c (ie Mossie and Whirlwind) with these carburetors of early Merlins (or Perrigrines)?
I've never heard of such problems, and I suspect that the high rotational inertia that results from the twin's engines' outboard position made it difficult to achieve roll accelerations required to create carburetion problems.
>And from what I've read the Schilling's orifice (and other pre injection carb improvements) was that -G could be performed for limited time periods (a few seconds, not specified but probably much less than 30 sec) and inverted flight could not be maintained for useful lengths of time.
From the Pilot Training Manual for the P-51 Mustang (covering the D and K variants with Merlin engines):
"However, when the plane is in inverted flight, the oil pressure falls off because no oil reaches the scavenger pump. For that reason you must limit inverted flying to 10 seconds - which is plenty of time for any normal or combat maneuvers."
Regards,
Henning (HoHun)
