Mosquito rpm issue

[dannytherat]

Strange one this evening - started a quick mission with the Mosquito and the revs I could get out of the engines were way lower than I would have expected (and indeed significantly lower than I got when I played yesterday). I was playing fully manual, with the a/c starting on the runway, and hadn't changed anything in my setup)

 

For example, when I throttled up to +18lb boost for takeoff (props set to max) I only got 2850rpm instead of 3000rpm. Also at +4lb boost I only got around 2200rpm (once again props to max) which is very low indeed compared to what I expected (and previously achieved)

 

To try to check that I hadn't done anything silly like setting the prop to auto, I tried the Hurricane and Spitfire IX (not least because they're both Merlin powered) and they managed 3000rpm (prop to max) for takeoff at +12lb boost (and indeed at significantly lower boost values than that).

 

Tech chat on the Mosquito indicated that I had indeed set the props to max but the rpms I was getting didn't really bear that out.

 

I'm not sure if this is a technical issue or user silliness, but I'd be grateful if anyone has any ideas.

[Jaegermeister]

Last time I heard something like that it had to do with "Engine warm" not being checked in the difficulty settings.

[dannytherat]

Funny thing. Just checked again and at +18lb boost I could only get 2850rpm during the takeoff roll but once I was airborne but still on full boost for the climb out, the rpm gradually increased to 3000rpm and thereafter continued in a more normal fashion.

Edited June 6, 2022 by dannytherat

[IckyATLAS]

On 6/6/2022 at 1:37 AM, dannytherat said:

Funny thing. Just checked again and at +18lb boost I could only get 2850rpm during the takeoff roll but once I was airborne but still on full boost for the climb out, the rpm gradually increased to 3000rpm and thereafter continued in a more normal fashion.

Something with the propeller governor simulation maybe. The angle of attack of the propeller blade may not be optimal to get 3'000 when the plane is sitting or rolling at low speed.

[dannytherat]

7 hours ago, IckyATLAS said:

Something with the propeller governor simulation maybe. The angle of attack of the propeller blade may not be optimal to get 3'000 when the plane is sitting or rolling at low speed.

Yes, I think you must be right

[Gingerwelsh]

Aircraft clean, full fuel.

 

Running up against the brakes, 18 or 20 boost , I got 2,860.

 

Let go brakes, the revs dropped to 2,730 and gradually increased to 3,000 by 120 mph.

 

rad temp starts at 40 deg. Warming to 100 deg made no difference.

 

Different OAT made little difference.

 

T/O rpm is supposed to be 3000.

The behaviour observed is as you would expect from a fixed pitch prop.

 

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Edited June 8, 2022 by Gingerwelsh

[FeuerFliegen]

Some planes, at their finest pitch angle (max RPM), is only fine enough to hit max RPM beyond a certain airspeed.  The Mossie could have been this way in real life, and if so, the sim is correct to act this way.

[Gingerwelsh]

4 hours ago, SCG_FeuerFliegen said:

  The Mossie could have been this way in real life,

Except that it isn't.

 

Part of a post service examination, is that the engines will obtain Max boost and 3000 rpm whilst static, because it's important to have max power at this critical point and maintain it throughout the take off stage.

 

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