Bug 174 on 12lbs boost. Review please.

Could you add any indications of the duration for which running at 12lbs / 12.5 lbs was allowed? They would have to model engine damage if the time was exceeded and is essential for any correct FM/DM

[Glider]

The official limit was 5 mins but there was nothing to stop pilots going for a lot longer than that. Dowding issued a memo to all pilots that warned them of overusing the boost. In some of the combat reports you sometimes see words along the line of switched guns to fire, lowered the seat and pulled the plug.

[Osprey]

@Banks: Thanks.
@Stormcrow: Pilot notes specify the limits.

[Bonkin]

Wow. That's a wealth of information that you have accumulated there Osprey.

I have an original Air Publication 1565A "The Spitfire I Aeroplane Merlin II Engine" manual which I thought might be useful - but I think those references you have must cover it all. I went through it specifically looking for performance charts but unfortunately there are none. There are change bars around the fuel and pitch sections though... and it states:

Fuel ....... Specification D.T.D.230
Note:- 100 octane fuel may be used, if the engine has been suitably modified.

Under the Automatic boost control it does mention +12lb/sq.in at sea level but does not tie this to 100 octane fuel.

[Osprey]

Just had a speed test in the Rotol Hurricane. Couldn't get more than 230mph ASi out of it, trimmed, level flight, at various RPm (best 2650). According to this:

http://www.wwiiaircraftperformance.o...rricane-I.html

I should get 261mph with the Rotol which is 290mph TAS.

[Biggs]

i have a feeling as well that we will not have correct speed performance for these engines for a while.

I applaud the efforts of you and others to try and keep this issue near the forefront... 1C needs to get it right.

Originally Posted by Biggs

i have a feeling as well that we will not have correct speed performance for these engines for a while.

I applaud the efforts of you and others to try and keep this issue near the forefront... 1C needs to get it right.

Same feeling. The tendency of the last beta patch is clear. Instead of improving the performance of all planes minus the spit 2 they degrade the spit 2 and the hurri. Even though now relative performance is restored historic wise we are now further from historic absolute values. I wonder if this is an integral part of the strategy in the light of the upcoming sequel.

(ok, I may be simplifying a bit but overall this is the tendency how I see it)

[IvanK]

Originally Posted by Osprey

Just had a speed test in the Rotol Hurricane. Couldn't get more than 230mph ASi out of it, trimmed, level flight, at various RPm (best 2650). According to this:

http://www.wwiiaircraftperformance.o...rricane-I.html

I should get 261mph with the Rotol which is 290mph TAS.

261 IAS converting to 291TAS is a huge difference at sea level. 30 Mph diff is not feasible.

[Osprey]

Apologies IvanK, I missed you off the list to review my OP, please advise anything you think is incorrect.

Regarding your comment though, what do you mean by 'not feasible' in this context? You mean it just shouldn't happen because it is a lot? Trouble is it is actually worse than just 30mph because this is WITHOUT 12lbs boost, so you can add another 25mph to that figure. Essentially the Hurricane is 50-60mph too slow. When I looked at the graphs too the 109 is faster than RL up to 6km too, so we have an inaccuracy of around 80mph!!