Spitfire & Hurricane flight model & engine performance thread. (1.09 patch)

JtD · #1 10-13-2012, 11:41 AM

I'm afraid zeno is inaccurate here. I think I have the Spitfire II pilot notes without any amendments, at least the amendment list is there and empty. This should be the original version dated July 1940. In there, the engine limitation for all out level is 9lb boost.

It appears that the all out level increase was at latest added with amendment list 31 / L, at a date that is not known to me.

The zeno version is missing the amendment list and does not shed any light on the "when".

Osprey · #2 10-13-2012, 11:58 AM

It doesn't matter. If you had a 109 on your backside or gave chase then you'd hammer the thing. I'm pretty sure that most 19 year olds don't drive 'according to approved ratings' but it doesn't mean it can't do it

JtD · #3 10-13-2012, 12:14 PM

It does matter, because it was necessary to modify the automatic boost control in order to have it deliver 12lb when in override. It would always have been possible to override it, but in the worst case you could end up with boost exceeded 30lb and destroy the engine instantly.

Kurfürst · #4 10-13-2012, 12:17 PM

Indeed JtD.

bongodriver · #5 10-13-2012, 12:19 PM

And there you have it....12lbs boost up to 1000' for take off or for a maximum of 3 minutes otherwise.

I'm sure nobody is suggesting 3 minutes was used to get to 1000'

JtD · #6 10-13-2012, 12:24 PM

A different system, bongodriver. It was limited to low altitude and could not provide boost at higher altitudes. Simply put, it had a full throttle altitude of 1000 feet, which would give you less than 9lb at altitudes exceeding 4000 feet. It's really just a take off setting.

Osprey · #7 10-14-2012, 08:31 AM

Quote:

Originally Posted by JtD

It does matter, because it was necessary to modify the automatic boost control in order to have it deliver 12lb when in override. It would always have been possible to override it, but in the worst case you could end up with boost exceeded 30lb and destroy the engine instantly.

Not with the Spitfire II which is what Kurfurst is talking about. This has a Merlin XII engine designed for 100 only.

I am not sure why Kurfurst agreed with you in the subsequent post unless he forgot which aircraft he was talking about

Quote:

Originally Posted by JtD

A different system, bongodriver. It was limited to low altitude and could not provide boost at higher altitudes. Simply put, it had a full throttle altitude of 1000 feet, which would give you less than 9lb at altitudes exceeding 4000 feet. It's really just a take off setting.

I agree, I don't have a problem with that, but it's the clearance to use it I'm talking about.

When I was 18 I didn't have clearance to take my engine in my Ford Fiesta 1300S into the red all of the time but when my six was occupied by another kid in an Escort or Golf I pulled the tit and away we went down those country roads like dickheads. After a while I blew the camshaft out of the side of the block, I'm pretty sure Ford didn't recommend this.

I should scan a photo of my heap of crap, I would've killed for one of these.