Mosquito supercharger guidance

[Harlequin]

Hi.

Going to start focussing on flying the mosquito for a while.  I have mostly flown German fighters so not famiar with the use of superchargers, but do understand the principle.

In the aircraft notes it mentions that for 150 octane fuel, you should manually change the supercharger gear at 3500ft (something like that specified in the notes).  My question is, is that for all conditions or only when trying to run at max power?  Do I just change the gear when I cross that height threshold and then just leave it alone?

 

Many thanks 

[LukeFF]

You need to switch it at low altitudes if you want max power with 150-grade fuel, otherwise you'll only draw about +18lbs boost.

[Hook_Echo]

When you are cruising above the recommended change over altitude, you can run it in low gear still and run the throttle all the way open or whatever throttle position gets you to the boost you want. That will get you better fuel economy as the supercharger draws less power off the engine in the lower gear. In cruising conditions I'm almost always in low gear unless I'm WAY up. If you can get the boost level required in combat mode you can leave it in low gear too, that would be right around the switching altitude. If you're in WEP you will need it in high gear to get all the boost.

 

Look at the recommended engine settings and then keep an eye on the boost gauge and adjust that accordingly. I mainly fly the Spit IX and Mustang with similar engines. Opposite to most advice for other planes it's best to adjust the boost first, then the rpm. The Merlins like to over rev and that hurts the engines. Also, in WEP if you pull the rpm back slightly to the combat setting (2850 rpm) but leave the throttle open all the way your WEP timer will extend to around 10 mins. But again keep an eye on the boost. If your boost drops at different altitudes you'll need to go back to full rpm to get all the power.

[Harlequin]

Ok. Thanks very much for the advice.  Will try things out and see how I get on.