What am I doing wrong? 2-stage prop spitfires.

[Space Communist]

Originally Posted by Buzpilot

Could it be that MkIa two stage prop in reality use different coarse than ingame, like gear 1 and 2 instead of 1 and 4th gear?

Edit; It's coarse, not course like many in here use http://dictionary.reference.com/browse/coarse

Ah yes you are right of course. I am just so much more used to typing that rather than coarse.

I was actually kind of thinking along those lines (the pitch of the coarse setting being wrong) since the top speed of the MkII seems to be at around 2700 rpm, and the coarse setting of the Ia drops it down to less than 2200 in level flight. When I get a chance I will drop the rpm of the Mk II down to 2200 at full throttle and see what happens.

[Blackdog_kt]

The two-stage prop operation is essentially like exchanging one fixed pitch prop for another in mid flight.

What is the most tell-tale characteristic of such props? The fact that RPM is not constant for the exact same pitch value.

If you go faster the RPM will go up, if you go slower it will go down and all this while you're not even touching the pitch controls.

Why am i mentioning all this? Because even though setting the pitch to coarse might drop your RPM too much, you can still make it reach the 2700 RPM sweet spot by speeding up a bit

Give it a bit of a shallow dive and trim level as you pick up speed and it wants to pull the nose up, you'll see she picks up speed and keeps it in a much better way.
Hope it helps

[justme262]

I just did a test in Spit Ia and got IAS of 255mph @ 17300ft @ 2750rpm on coarse pitch setting.
I put that into a TAS calculator and got 342mph.
I was running level till the speed stabilized after a shallow dive at about 270mph IAS. But it was holding pretty steady for 20 seconds or so.

The course prop setting gives much higher RPM at altitude where the air is thinner. I have come to like de Havilland two speed props. I think they actually historically had a better top speed than the Rotol prop fitted versions. But the Rotol had better climb and acceleration. You just gotta be at high alt to get the most out of em...




http://www.csgnetwork.com/tasinfocalc.html

[robtek]

if that sideslip was there all the time you could have gon even faster by correcting it.

[justme262]

I'm sure I could have gone faster...
I was trying to fly as even as I could with just rudder and elevator trim. with out aileron trim I couldn't get it dead straight.

I had half a tank of fuel and full guns... radiator half open... and didn't even touch the boost cut out.

With 5% fuel, empty guns, fully closed radiator, and throttle pushed through the gate I think it might do 355mph TAS.

http://www.spitfireperformance.com/spitfire-I.html

[Ze-Jamz]

What high alt are you talking about? That Aicraft is horrible to fly at high alt, handles like a pig and is very easy to overcook the engine

[justme262]

The original poster said he tested at 4000ft. The spit mkI had it's best speed at about 17 or 18000ft. That's much higher altitude.
The spitfire flys beautifully at any altitude. At least when I fly it...
maybe you just need a little practice

Someone suggested the mkI and mkIa ingame are running on 87octane at 6.25lb of boost and the mkIIa is running on 100octane at 12lbs of boost. Supposedly the mkIIa's running 12lb of boost still had an old boost gauge that only went up to 8lbs though. I vaguely remember checking this ingame.

Anyway that would still make our mkI spits more like Battle of France performance not Battle of Britain performance.
The 3d model on the mkI is a DH prop and the 3d model on the mkIa is a Rotol prop. If you look at them from outside. Same prop models as on the hurricanes.