Spitfire Question
 

I was telling an ex Navy pilot and aircraft historian friend of mine about IL2-Sturmovik BOP game ...and he asked me to check something out. Since it will be hours before I can play again, I thought I'd ask the question here.

According to him, the Spitfire had a known issue with the float in the carburetor.... he said if it was flown inverted for too long that the engine would die. Can anyone confirm this as a fact...and does anyone know if it happens in game?

yes the merlin engine did have this problem ... but in game?? lets check it out... brb in 10 ;)
I know the mk XVI has the griffon engine... and I dont know if it had the same problem... so I will take another spit

nop....it keeps on flying (tried with the spit mk II because that one for sure has the earlier merlin engine)

The game doesn't have it, this is because they have accurately modeled the Mk 2 spitfire and not stuck the Mk1 in with a pair of cannons :D
By the time of the Mk 2 they had identified this problem as the fuel was forced through by gravity not a pump. I believe tall they had to do was place a piece of mettle inside the eenginethat swivels and was weighted in a way that in negative 'G' it would swing down and stop fuel flowing backwards. Although i may be wrong on the solution bit :D do correct me if i'm wrong!

did they fix it in the mk II allready? I thought all merlins till at least the mark IV had the problem (IV is the first one with the griffon engine right ? :rolleyes:)

Somehow I knew this would spawn an interesting conversation....you guys are fascinating to listen to. :)

I did some research and found that indeed did the pilots could help the engine by inserting a piece of metal... but that didnt really fix it. because for this 'fix' to work..they HAD to dive at full power, wich was not always what they wanted. It was only in the last 100 series merlin that they put in a direct injection fuel pump .

The 60-85 variants also had a fuel pump...but this one did not have enough power. The 100 variant was using the crackshaft speed.

Now...I do not know wich spit had exactly wich variant of merlin :P.. but I think the mk2 was to early to benefit from the fuel pump variants


EDIT: this is what I found on wiki
the Merlin's lack of direct fuel injection meant that both Spitfires and Hurricanes were unable to pitch nose down into a steep dive. The contemporary Bf-109E, which had direct fuel injection, could "bunt" into a high-power dive to escape attack, leaving the pursuing aircraft behind because its fuel had been forced out of the carburettor's float chamber by the effects of negative g-force (g). RAF fighter pilots soon learned to "half-roll" their aircraft before diving to pursue their opponents.[25] "Miss Shilling's orifice",[nb 5] a holed diaphragm fitted across the float chambers, went some way towards curing the fuel starvation in a dive; however, at less than maximum power a "fuel rich" mixture still resulted. Another improvement was made by moving the fuel outlet from the bottom of the S.U. carburettor to exactly halfway up the side, which allowed the fuel to flow equally well under negative or positive g.[26]

Further improvements were introduced throughout the Merlin range: 1943 saw the introduction of a Bendix-Stromberg pressure carburettor that injected fuel at 5 pounds per square inch (0.34 bar) through a nozzle directly into the supercharger, and was fitted to Merlin 66, 70, 76, 77 and 85 variants. The final development, which was fitted to the 100-series Merlins, was an S.U. injection carburettor that injected fuel into the supercharger using a fuel pump driven as a function of crankshaft speed and engine pressures.[27]


still ... I dont know what aplies to wich spit

I've read that the F4U used to stall on the starboard wing before the port one at low speeds

Yeah...I heard the same thing... but I could never figure out why this would happen :confused:. I can imagine it to happen at a go-around due to sudden torque effects... but I heard that the problem was mostly while landing on the carriers.
I understand that landing brings you close to stall speed...but why would one wing have this before the other one? prob because of the ugly looking wings :P

That would be the MkXIV with the Griffon.

OH DAVID!!! WHERE ARE YOU!!? :P :cool:

no right? mk XIV? I'm pretty sure the mk XII has it (not sure at all about the other one i mentioned).

David...we need you indeed :P

"The Mk XII was the first Spitfire powered by a Griffon engine to go into service."

If we dont have david...we use wiki :cool:
http://en.wikipedia.org/wiki/Superma...ed_variants%29

Yes, the Mk XII also had the Griffon engine. But it is the MkXIVs (I believe) that really proved the Griffon Engine, and they are better known to have the Griffon.

DAVID!!!! :cool:

This sight should give you some info on some varients: LINK

I asked a guy who did aeronautical engineering at uni how it was possible, and he didn't actually know.

I just learned another interesting fact about the Spitfire when it was converted for carrier use into the Seafire Mk47...in that because it was geared with a counter clockwise prop rotation (from the cockpit) that they had trouble during takeoff of hitting the flight control bridge to their right because of the opposite rudder control needed. I guess the new pilots were too used to right rudder, wow. Then came the counter rotating props to correct for this, damn, I learn something new every day. Thanks for the input all.

Please explain...

I didnt quite get what you were saying... but I read a few times over ... and only then I saw you were talking about the seafire 47 :P..
So you are saying... because the pilots were used to applying right rudder (because of the torque to the left)... the also used right rudder in the seafire 47 :P.. Even though the 47 was eliminating the torque effect with its 2 props :P. Thats ... well.. not hilarious... but still :P LOL

I don't understand how the starboard wing could stall prior to the port wing...It would be interesting to read about if anyone knows the answer. All single engine prop driven aircraft have left turning tendencies-P-Factor, Torque, spiraling slipstream, gyroscopic precession. P-Factor occurs at low airspeeds and high angles of attack when the descending blade(s) create more thrust than the ascending blade(s) due to a higher angle of attack. Because of this there is a center of thrust created on that side. This and torque are the primary causes for the left turning tendency in single engine aircraft. Because of this higher center of thrust on the descending side of the blade, there is a higher center of lift directly aft of this area which could perhaps explain why one wing would stall prior to the other. If this is true Corsairs must have been very susceptible to spins (spin=the result of an uncoordinated stall in which one wing is more stalled than the other). However this theory wouldn't work if the Corsair's propeller rotated clockwise because the port wing would be the first to stall.

I've read that the Corsair did have a tendancy to drop one wing in a stall,
don't know if it was always the same wing though.
Apparently the problem was rectified with a :!:strip of wood:!: acting as a spoiler on one or both wings.

I think it was always the right wing.. but I still wonder why... and what is that piece of wood changing...so it makes the wings stall at the same time :confused:. (not saying you're wrong...found the same thing about that 'piece of wood fix')

Well actually he is right. The first griffon powered Spitfire was the mk IV,It was the prototype mk IV then renamed to mkXX and then renamed again to mk XII. The Mk XIV was the next step on and was fitted with the same 2 stage supercharger that the Merlin Powered mk IX already had.

I'm pretty sure the Mk II's Merlin was effected by negative G's. It's disapointing that the game doesn't show this. It was one of the main things the 109 Emil was able to exploit to their advantage. In BoP the Spitfire mkII seems far better than the Emil.

Engine cut out due to fuel starvation is in the game though. It happens in the I16 and I153 almost instantly if you go into a steep dive. Its just anoying you can't get it started back up again.

I believe the strip was placed in a position that would disrupt the airflow
over the wing to reduce lift. Engineers back then were so clever!

Right, but it was just the early single prop version that gave them the grief, the problem was resolved with the dual, counter rotating prop.

The Spitfire MkI was always affected by negative G making the engine cut out, as were early MkIIs, but later MkII models were fitted with a makeshift but effective fix invented by a female engineer named Betty Schilling. Since the MkII in the game is the cannon equipped B model, it would almost certainly have the fix.

From the Merlin 66 engine onwards, Spitfires had pressure carburettors, which all but cured the problem.

Incidentally, if people are wondering why Rolls Royce kept using carburettors instead of fuel injection despite the obvious disadvantage under negative G, this was because it allowed the light and relatively small 27 litre Merlin to compete on power outputs with the bigger 33.9 litre DB601s and even the later 35.7 litre DB605s used by the Bf109 family. The carburettor system was even kept for the 37 litre Rolls Royce Griffon, which in its later forms was capable of over 2,400hp, where even the most powerful variants of the fuel injection DB605 could only produce 1950hp.

There we go :)... thnx for clearing it up david :)
Any idea as to why one wing of the F4U would stall before the other?

At a guess, the torque from the prop is affecting one wing more than the other. Say the prop is rotating clockwise from the pilots point of view, as on the Corsair, this will mean the plane will be trying to roll left. This will have the effect of increasing the amount of lift the left wing has to provide, so if you are on the point of stalling it will be the left wing that drops first, and vice versa if the prop rotates the other way.

This fits with the Corsair's tendency to stall and drop its left wing if power was suddenly increased when flying slowly, but I'm not sure why it also has a reputation for stalling and dropping the right wing if power was kept constant and the plane was allowed to slow down to stall speeds. I took a Corsair up in Il2 1946 to test this, and tried flying at a safe altitude with the flaps and gear down at low speed, and then seeing which wing dropped first, and it was always the left wing, regardless of whether I throttled up or let the plane stall on its own because of a lack of airspeed.

I really should look into this more, because I was just flying a combat mission with a Spitfire XIV and I pranged it on landing because I was coming in below the glide path, so I throttled up and the right wing dropped and smacked me into the ground. Plane didn't blow up, because I only dropped about 20ft, but it was a total write-off.