Mosquito Oddities

[Bert_Foster]

Boost cut out

Merlin 25 Mosquitoes did not have Boost cut out fitted, yet the cockpit model has the control fitted

https://i.postimg.cc/1XYgj7pV/Mosboostcutout.jpg

 

150 Octane and 25Lbs Boost

The only way I can get 25Lbs Boost is if the Supercharger switch is in AUTO ..this is an error imo. 25Lbs Boost should not be dependent on SC mode. In AUTO below 12,500ft then the SC will always be in Low (MOD) gear. 25Lbs Boost should still be available.

 

Take Off YAW

in the Sim the aircraft yaws RIGHT as power is applied. Aircraft should YAW LEFT on take off. Pilots notes Part II Handling para 49 Take Off " There is a slight tendency to swing to port ...."

Edited July 5, 2022 by Bert_Foster

[busdriver]

59 minutes ago, Bert_Foster said:

Boost cut out

Merlin 25 Mosquitoes did not have Boost cut out fitted, yet the cockpit model has the control fitted

 

Did you see that little red placard below the Boost Cut Out handle?

 

 

59 minutes ago, Bert_Foster said:

Take Off YAW

in the Sim the aircraft yaws RIGHT as power is applied. Aircraft should YAW LEFT on take off. Pilots notes Part II Handling para 49 Take Off " There is a slight tendency to swing to port ...."

 

The Devs have been reminded of this error from the gitgo.

Edited July 5, 2022 by busdriver

[Bert_Foster]

Nope didnt see should look closer next time

[FeuerFliegen]

1 hour ago, Bert_Foster said:

 

150 Octane and 25Lbs Boost

The only way I can get 25Lbs Boost is if the Supercharger switch is in AUTO ..this is an error imo. 25Lbs Boost should not be dependent on SC mode. In AUTO below 12,500ft then the SC will always be in Low (MOD) gear. 25Lbs Boost should still be available.

 

Been a couple weeks since I flew it so not sure if it's been fixed, but I recall that with 150oct that it seemed like the supercharger gear had to be switched manually, which is how I recall the Spitfire IX 150oct being (which it tells you in the notes), but the Mosquito, it does not tell you this in the notes.

[busdriver]

5 hours ago, Bert_Foster said:

Nope didnt see should look closer next time

 

No worries mate. ?

[-=PHX=-SuperEtendard]

7 hours ago, Bert_Foster said:

150 Octane and 25Lbs Boost

The only way I can get 25Lbs Boost is if the Supercharger switch is in AUTO ..this is an error imo. 25Lbs Boost should not be dependent on SC mode. In AUTO below 12,500ft then the SC will always be in Low (MOD) gear. 25Lbs Boost should still be available.

The first supercharger gear doesn't have enough compression to reach +25lb of boost at sea level, so at sea level with ram speed you get around +22 / +23 boost, as soon as you climb this will start to decrease as air pressure decreases and the supercharger is at full throttle already.




Notice here in the Boost part of the graph how the first supercharger gear is never at +25 boost and immediately starts losing manifold pressure as soon as you increase altitude, for this supercharger ratio critical altitude for +25 boost is effectively below sea level (with standard atmosphere).

However using the second supercharger gear to achieve +25 boost at sea level still gives less power due to throttling losses, as the graph shows (you can see a lower top speed at sea level with FS gear vs MS gear).

You need to be above 3500 feet to get more power out of the engine at +25 boost on the second gear, at least for level top speed. If you are climbing or maneuvering, the ideal altitude to switch gears would be a bit higher because of the lack of ram effect. Once you go below +20 boost in first gear is when switching to second gear for +25 boost would give a net gain in power.

Edited July 6, 2022 by -=PHX=-SuperEtendard

[Bert_Foster]

Okay thanks SuperEtendard. Read the report.

 

Also noted the in game Note when select the 150 Octane that SC Auto Shift is deactivated and needs to be done manually ... so now makes sense. That agrees with the report though in this case it was a test aeroplane with specific reference to the fact that the SC changeover was specifically moded to permit selection at will of MS and FS gear. I assume that this mod was then applied to Operational aircraft utilizing 150 Octane ?.... though cant find a source document that confirms this.

 

100 OCT AUTO SC Shift.

Most documents (and Test reports) indicate that the shift on the Merlin 25 occurs at 12,500' on the way up .... in the Sim its happening at 8000'

[Gingerwelsh]

6 hours ago, Bert_Foster said:

Okay thanks SuperEtendard. Read the report.

 

Also noted the in game Note when select the 150 Octane that SC Auto Shift is deactivated and needs to be done manually ... so now makes sense. That agrees with the report though in this case it was a test aeroplane with specific reference to the fact that the SC changeover was specifically moded to permit selection at will of MS and FS gear. I assume that this mod was then applied to Operational aircraft utilizing 150 Octane ?.... though cant find a source document that confirms this.

 

100 OCT AUTO SC Shift.

Most documents (and Test reports) indicate that the shift on the Merlin 25 occurs at 12,500' on the way up .... in the Sim its happening at 8000'

 

It's 12,500' in the 1944 Mk IV manual, but 7.000' in the 1950 Mk 6 manual.

Many other things suggest that the 1950 manual is being used for our Mosquito.

 

I get 7,600' change at full throttle 3000 rpm and 8000' at 2850 rpm.

 

With 150 oct the change can be made at any altitude, using the auto switch.. This isn't documented in either manual.

 

..

[Bert_Foster]

Thats interesting Gingerwelsh. Went looking at all the various pilots notes available. Indeed the post war notes talk about 7000' but all the wartime manuals and test reports for Merlin 25 variants list 12,000'.

 

I think the devs need a closer look at this.

[thrila]

It's my understanding that 150 octane fuel lowers a supercharger's full throttle height. The values you both observed match the heights in SuperEtendard's chart and supporting 150 octane trials documentation from the same website.

 

Edit: Sorry, I forgot to link document http://www.wwiiaircraftperformance.org/mosquito/hx809.pdf

 

Edited July 8, 2022 by thrila

[Bert_Foster]

We are talking about 100 Octane AUTO SC shift ht not 150Octane with Manual Shift change

100Oct Mosquito test:

 

http://www.wwiiaircraftperformance.org/mosquito/hj679.pdf

 

All Wartime pilots notes say the same:

 

 

Edited July 8, 2022 by Bert_Foster