I know the Spitfire needs a starter cart, to start the engine on the ground, but if the engine should be stopped in the air, whilst flying - can it be restarted?
Spitfire engine
- Thread starter Harry Bloomfield
- Start date
I think I've see old films with prop planes that have been in the same boat and whether it's artistic licence or not, they have gone into a very steep dive so as to make the prop turn the engine over. Does make you think though, what's the compression ratio of a serious engine like that. Is there a valve decompressor on all 12 pots? Ahhh...
I don't know! I was just watching something on TV, about the RR Merlin, where they were having trouble with the original design, where the engine would stall in a steep dive, cured by 'Miss Shillings Orifice'. I just wondered how disastrous an engine stall might be.
Yeah, not a clue about the prescribed way of restarting it. I just skimmed the wiki article on the "orifice" and ironically, putting it into a steep dive is how you undesirably flood the engine thereby stopping it in the first place Ha ha. Having said that, I guess it would only be the initial part of the dive that that would neg-g it. As soon as the plane was completely nose down doing 150/200MPH or whatever I suppose the neg-g would go away, less than one G would come about and the prop would be wind milling enough maybe? Presumably you'd need carp loads of altitude to get that airspeed though. I used to fly RC planes (not that you’d get a model to do it) and have a tiny bit of knowledge... I think ? : - )
More like a cough & splutter but enough to give advantage to the other side, no worries about a big prop windmill turning the engine over as I recall compression was only about 6:1 remember lots of charge compression came from the enormous centrifugal blower that took 3-400Hp to drive it!
Before Miss Shillings solution was found the pilots worked out how to get into a dive without negative G with a clever roll into dive maneuver I believe. Amazing engine but some real bunfights during it's development in the 1930's see Merlin history for example
Interesting stuff 42. I always think of powerful engines as having high compression, but it was way back then when the strokes were long etc. was just reading that the opposition had injection engines... Always were good at that stuff. Such clever people mislead by a nut case, so sad.
There was a good reason Rolls did not and that was charge cooling by fuel evaporation that dramatically reduced detonation problems (and increase charge density) before really high octane fuels became available later in the war. They added simple single point injection into the blower eye much later maybe to save space at the back end to help shoehorn the two stage blower into the Spitfire airframe). Remarkably later they managed to shoehorn the Griffon a 37 Litre engine in there as well the Merlin being just 27 Litres, engineering at it's best.
Last edited:
I think the introduction of a carburettor cured the problem at altitude when the aircraft was in a steep climb.
Injection engines. OK fair enough, Rolls knew what they were doing – no surprise there, certainly was engineering at its best and under the pressure of conflict. Makes you wonder where all our brit genius engineers are today. As far as the shape of it (non clipped vers), it makes you wonder what thoughts ran through the head of the first pilot that came up against one. It must have been like when we all got to see the F-117. What a wonderful aircraft the spitty was.
Odds - yeah sure, aspiration played a big part in honing this planes performace throughout it seems.
Odds - yeah sure, aspiration played a big part in honing this planes performace throughout it seems.
I like the fact that the engineering allows the pilot to alter the pitch of the prop' blades (as with most propellors), whilst in flight. I thought it was a clever bit of engineering on the Merlin engines. Makes sense when you think about it.
It's the sound of that engine which always gets me - and i don't know why. I mean, the war was over 20 years before i was born but there's something about the sound that just makes you look up whenever one of those planes flies by. It's such a beautifully designed aircraft, like one of those 1920s sports cars, finished with wood interior and a hood ornament that glints in the sun.
Over forty aircraft were fitted with the Merlin but only one commands an iconic status like a Spitfire.
Over forty aircraft were fitted with the Merlin but only one commands an iconic status like a Spitfire.
I visited an indoor radio rally down in Lincs once, and a special, low altitude flypast of the Spitfire, Lancaster, and Hurricane had been arranged, on route to, or from some other event. That building, cleared in seconds, as everyone rushed out at the sound of those Merlins.
Some years ago the local town council festival, just a few thousand people, had the full battle of britain flypast, it turned out the ex raf mayors assistant had the right connections and arranged for the display. I believe they do several on the day so we were probably en route, but an amazing sight, they did quite a few passes.
Blup
The sounds and the shape of the Spit are well demonstrated in this video Spitfire
As an engineer I sometimes think of the Merlin as an early gas turbine with an unusual reciprocating combustion chamber
Stanley Hooker might agree!
Anybody interested in this line of thought could look up the post war Napier Nomad for probably it's ultimate expression.
As an engineer I sometimes think of the Merlin as an early gas turbine with an unusual reciprocating combustion chamber
Stanley Hooker might agree!Anybody interested in this line of thought could look up the post war Napier Nomad for probably it's ultimate expression.