P-51D Engine AH and Pilot Handbook

[bozon]

Nitrous oxide was used by the British and the Germans in a few specialized high-altitude aircraft to increase performance above full pressure height. It didn't boost the engine above what was normal. It gave the engine the oxygen it needed when the supercharger no longer could deliver enough pressure.

RAF used N2O in night fighters to catch LW bombers and night-fighters in defense of Britain, where the typical altitudes were 20,000 feet, near the Mosquito full throttle height in F.S. gear.
I dont know how much speed it gave at 20,000, but this document from http://www.wwiiaircraftperformance.org says it gave NF.XIX (Merlin 25's like our FB.VI) about 17 mph at low altitudes:



394 mph at 2000 feet... not to bad for its time

[GScholz]

Nitrous will always give a boost in power even at sea level, that's why the ricers are using it.    However in WWII it was mostly used to increase performance at high altitude.

We have one NO2 boosted plane in AH, the Ta 152. Or at least I think our version of it has the GM-1 booster, though it seems to be underpowered at very high altitudes in AH. The real one could do 470+ mph at 40,000 ft using GM-1 boost.

[GScholz]

Yes, it has the same GM-1 saw-tooth pattern, but it seems to be under performing a bit up high.

[BnZs]

UNLIMITED WEP FOR EVERYONE!!!

(Image removed from quote.)

Truly realistic engine modeling would basically amount to unlimited WEP for the typical AH sortie. That is why Hitech's by-the-book limit and automatic switchoff is the best possible compromise in terms of realism.

[GScholz]

There are many different possible variations on WEP limits. HTC's solution is OK in my book.

[artik]

The HTC solution is MORE than ok - it works very well for game-play.

Believe me, when I look on some other games IL-2, DCS P-51D... it makes me feel nausea.

I just wanted to understand the difference I noticed in the pilot manual and AH plane.

[GScholz]

The mistakenly perceived difference you mean...

[BnZs]

There are many different possible variations on WEP limits. HTC's solution is OK in my book.

Historically pilots sometimes mistakenly left WEP on for much longer than it was meant to be used, like an hour or so, without engine failure. Power limitations are more about engine life than the small chance of the engine failing due to overuse. The leave wep on too long=engine failure modeling in other sims is unrealistic, for the most part.

[GScholz]

Depends on what engine you're modeling. I know of Merlin engines that have been run for hours on WEP, but they were on testbeds or in some cases bomber engines (Lanc). If a P-51 or Spit ran on WEP for an hour they would never have reached home due to fuel starvation.

[BnZs]

Depends on what engine you're modeling. I know of Merlin engines that have been run for hours on WEP, but they were on testbeds or in some cases bomber engines (Lanc). If a P-51 or Spit ran on WEP for an hour they would never have reached home due to fuel starvation.

One of the reports I'm thinking of involved a Spit and an hour I believe, but I'm honestly having trouble remembering the details. Must have been close to home. In any event, you can see that engine failure from WEP overuse is an unknown, thus leaving Hitech's solution the best one for realism in this case.

[GScholz]

A Spit doesn't have enough fuel to run on WEP for an hour. Very few planes do. In case of the Merlin WEP overuse rarely resulted in engine failure, but other engines were more high-strung and prone to damage. The Russian VK engines were already at only 24 hours between overhaul without any excessive abuse. The DB 605 could also explode if run too hard for too long. The Merlin was perhaps uniquely durable for a V-12 aero engine.

[danny76]

A Spit doesn't have enough fuel to run on WEP for an hour. Very few planes do. In case of the Merlin WEP overuse rarely resulted in engine failure, but other engines were more high-strung and prone to damage. The Russian VK engines were already at only 24 hours between overhaul without any excessive abuse. The DB 605 could also explode if run too hard for too long. The Merlin was perhaps uniquely durable for a V-12 aero engine.

That'll be the good 'ol British engineering 

[GScholz]

 

[TheCrazyOrange]

See Rule #4

[danny76]

See Rule #4