Spit/109 sea level speed comparisons in 1.08 beta patch

[Kurfürst]

Originally Posted by bongodriver

the 5 minute limit 'has' to be a guaranteed absolute minimum in order to be an allowed limit, the likelyhood of failure 'at' 5 minutes is low and increases proportionally with time beyond the 5 minutes, I don't care if the failure rate is 100% at 6 minutes it's just highly unrealistic to have guaranteed failure at 5:01.

I agree, I am pretty sure the Merlin could operate well beyond 5 minutes at maximum power, if the prescribed temperature limits are also observed at the same time. After all these engines usually went through 100 hour tests before service approval, tested for many many hours at full power, but with controlled oil and coolant temperatures.

As I understand the reason for Merlin engine failures in CLOD are probably related to:

a, Exceeding oil and/or coolant operating temperatures of the Merlin. Obviously engine failure is a very obvious conseqence of too high temperatures, so the real question is IMHO
aa, how long the Spit / Hurri could be run at + 6 1/4
ab) how long the Spit / Hurri could be run at + 12, which is about 30% more power/heat load.

b, Fall of oil pressure during negative-g manouvers, resulting that the engine is insufficiently lubricated, which can and will destroy an engine in very short order, any engine, and should be correct for the 1940 neg-g sensitve Spit/Hurri (which's manual specifically warns against negative-g and low oil pressure conditions), so I sense that Red pilots not knowing/ignoring this limitation may be at the culprit.

[Dami55an]

The graphs having different scales makes it very hard to compare

[Crumpp]

Which Graphs?

[JtD]

What is the input data for your calculation?
- clmax (or stall speeds used + source)
- cdo (or power output, boost, rpm and speed + source)
- weight (source)
- assumed wing efficiency
- assumed prop efficiency

I would think the relation is about OK, but both planes are turning too fast and I also think that the high speed relation is a bit off.

[Christop55her]

I don't care if the failure rate is 100% at 6 minutes it's just highly unrealistic to have guaranteed failure at 5:01.

[Crumpp]

What exactly would be your definition of good data?

Data that matches the characteristics of the engine and makes sense.

If our engine has a RAM FTH of say 12,000 feet and our data shows a FTH of 8,000 feet....

It is not the same engine in the airplane. If we use the power data from the wrong engine with the wrong speed....our result's will be just as incorrect!

[Crumpp]

NzTiffoon says:
109 the trim for all control surfaces had to be set on the ground

Crumpp says:
fixed trim

Grab a dictionary and look it up....

Also, go to the local airport and ask a mechanic about the number of airplanes that just have longitudinal trim controls. It is pretty common for a well designed control system. Most modern SE airplanes have fixed trim for everything but the elevator.

[Al Schlageter]

Originally Posted by Crumpp

It is pretty common for a well designed control system. Most modern SE airplanes have fixed trim for everything but the elevator.

So you are saying that the Americans did a bad job in designing the control system of their fighters as the had to put trim on the elevator, rudder and ailerons?

How many modern s/e a/c have a speed range of a WW2 fighter?
How many modern s/e a/c have a disposable load that a WW2 fighter has?
How many modern s/e a/c swing a 10' plus prop turned by 1500hp plus engine?

[NZtyphoon]

Originally Posted by Crumpp

Grab a dictionary and look it up....

Also, go to the local airport and ask a mechanic about the number of airplanes that just have longitudinal trim controls. It is pretty common for a well designed control system. Most modern SE airplanes have fixed trim for everything but the elevator.

So what? As per ususl Crumpp conflates modern civilian practices for sports aircraft and says this should have been the same on high speed fighters during WW2 How many high speed WW2 fighters has Crumpp flown?

Originally Posted by Crumpp

Why do you think the trim on the Bf-109 is set to 400 kph IAS???
Having a fixed trim condition is a great way to set the combat speed for your airforce.

Utter balony, it's a great way to ensure that once in flight pilots do not have the ability to trim the aircraft to suit the circumstances - the 109E rudder became increasingly heavy, to the point where it was almost impossible to use - it's interesting that later "tall tailed" 109 variants had a trim tab to help overcome this problem. Setting the "combat speed" to a uniform and abitrary 248 mph? What's the point of that?

Any WW2 fighter that used trim controls rather than fixed trim was, by Crumpp's definition, badly designed and therefore inferior to uber Luftwaffe aircraft.

[Robo.]

Originally Posted by NZtyphoon

Utter balony, it's a great way to ensure that once in flight pilots do not have the ability to trim the aircraft to suit the circumstances - the 109E rudder became increasingly heavy, to the point where it was almost impossible to use - it's interesting that later "tall tailed" 109 variants had a trim tab to help overcome this problem. Setting the "combat speed" to a uniform and abitrary 248 mph? What's the point of that?

Any WW2 fighter that used trim controls rather than fixed trim was, by Crumpp's definition, badly designed and therefore inferior to uber Luftwaffe aircraft.

It's not a question of which airforce had 'better' trim system.

It was just a different approach in USAAF and LW. LW fighters had no variable rudder trim and a/c was trimmed for certain cruise speed, so at most typical cruise speed pilot would not have to kick the rudder to compensate for sideslip. Allied fighter pilot would twist the rudder trim and climb or fly with feet off. No biggie imho, just more comfortable.

What Crumpp is saying that Emil was trimmed for 400kph because that was best combat speed. That is obviously wrong, 400kph was typical cruise speed (achieved at some 1.15ata and 2200 U/min). This worked in game btw, but then the devs changed the fixed trim value for 300kph for some reason, which is too low and now LW pilots complain because the Emil is very unstable during combat phase:

See bugtracker issue No. 387: http://www.il2bugtracker.com/issues/387

There is nothing wrong with 109E turning well at 400kph, it's actually pretty obvious to any virtual pilot in here, e.g. fast Emil will outturn slow Spitfire with no problem for long enough to score some hits. But as for sustained turn advantage in typical horizontal turnfight and as for 400kph turn used in TnB combat for long enough to be called sustained turn, that's all nonsense. 109 will win if the pilot keeps the speed up, but not via sustained turn performance advantage. At co-E situation, Spitfire would outturn and hit a 109 turning at 400kph flat with no problem. Just for long enough to score hits.

I'd say Crumpp is not entirely wrong here but his statements are irellevant to what is actually important in TnB combat (re: sustained turn argument). I don't blame him for he has no experience with combat sims.

He's wrong in his statement that 109E was trimmed for 400kph purely for combat purposes. Fixed trims are usually set for cruise speed even for fighter aircraft.