Spit IIa Performance graph

[Crumpp]

Be carrefull with overboost at high altitudes

Which is realistic. At high density altitude, you will see a performance decrease at high boost and rpm. What happens is the prop tip speeds become excessive and you lose efficiency. So instead of increasing thrust, you actually reduce the thrust the propeller is able to produce.

In otherwords, at standard conditions and low density altitude you have the chance of realizing a performance increase at high boost and rpm.

You can also see by your test that the 2800 rpm data is almost an exact match looking at SL and your test FTH on a standard day. Your recorded FTH is off though for a standard day.

However, the FTH does not match 29.29inHg at 66.2F.

What are the temperature and pressure you recorded the data under?

I am not sharp shooting your effort. Trying to help you guys get the data you want to make sure all the FM's are correct. If you don't give the developers the information they need, then they cannot find the issue and fix it.

Some details that need to be included in each test:

Take off weight

There is a control somewhere to set the temperature and pressure. If you can set them too:

SL Temperature 15C
SL pressure 1013.25mb

Climb speeds

Engine settings and rpm

FTH

You have a well organized set of data that is easy to work with combined with visual graphs to spot trends. That is great.

Don't forget too that the details of the RL performance are extremely important as well. How the aircraft is set up, weight, configuration, etc...

All of these effect performance.

Lastly, aircraft performance is a percentage range so looking at a single set of data from a real aircraft may not be representative of the typical performance of the type.

For example, the Spitfire test P7280 does not seem to have a rear view mirror listed.

This aeroplane was fitted with a bullet-proof windscreen, armour plating over the petrol tank and externally, apart from the radiator, was similar to the Rotol Spitfire I, N.3171, previously tested at this establishment.

http://www.spitfireperformance.com/spitfire-II.html

The absence of a rearview will effect the Vmax of the airplane in the Spitfire. The presence of the mirror is noted in RAE test's.

Aircraft performance is all about the specific conditions!

[Seadog]

Originally Posted by Crumpp

Which is realistic. At high density altitude, you will see a performance decrease at high boost and rpm.

I'm getting really tired of your B&*(&*^t. It was virtually impossible to destroy an engine at high altitude because the engine simply can't produce enough boost to cause damage. High RPM was necessary to produce sufficient boost for the engine to develop maximum power. The boost at altitude graph that I posted earlier shows the engine holding 8.8lbs to 17550ft at 2990 rpm. The idea that somehow the engine would destroy itself at these boost levels is complete nonsense and shows how the simulation at it's current state of development is complete crap.

[Blackdog_kt]

Watch your language...

On the topic at hand, going fine pitch/high RPM while flying in low-density air decreases performance after a certain point. The air is "thin" so you need to coarsen the pitch (lower RPMs) to get a sufficient bite of air, otherwise the prop just spins around really fast without pushing the needed amount of airflow.

It's modeled the same way in 109s by the way (you get better performance if you drop your RPMs a bit at higher altitudes) and it's one of the first things i noticed and really liked in the sim.

[Seadog]

Originally Posted by Blackdog_kt

Watch your language...

On the topic at hand, going fine pitch/high RPM while flying in low-density air decreases performance after a certain point. The air is "thin" so you need to coarsen the pitch (lower RPMs) to get a sufficient bite of air, otherwise the prop just spins around really fast without pushing the needed amount of airflow.

It's modeled the same way in 109s by the way (you get better performance if you drop your RPMs a bit at higher altitudes) and it's one of the first things i noticed and really liked in the sim.

The engine cannot produce maximum power unless the supercharger is spinning at maximum speed to provide maximum boost. The effect of prop tip speed is practically unnoticable with BofB RAF fighters at RPMs of 3000 or less because the props were designed to provide full power at this RPM and were sized accordingly.

[CaptainDoggles]

I thought we decided that the atmosphere in game was way off the mark?

[bongodriver]

Originally Posted by CaptainDoggles

I thought we decided that the atmosphere in game was way off the mark?

Not completely, there is a setting on the FMB which brings the atmospheric temparatures in line with ISA, but by default it seems the atmosphere is modelled as ISA + 10 which is perfectly feasible in the real world in summer time, with ISA +10 we can expect to see an underperformance from what is stated in aircraft flight manuals, the results of my atmospheric tests are in the hurricane speed thread.

http://forum.1cpublishing.eu/showthread.php?t=32523

at some point I wan't to check the pressure lapse rate but I don't think it makes for as big an issue as temparature.

[CaptainDoggles]

Originally Posted by bongodriver

but by default it seems the atmosphere is modelled as ISA + 10 which is perfectly feasible in the real world in summer time

That might be a map-wise setting, hard-coded lke we used to see in 1946. Be interesting to test if/when BoM comes out.

[=AN=Felipe]

Good afternoon gents

so, takeoff weight = maximun takeoff weight

Temperature and pressure default, default settings and weather...

Climb speeds at 160mph @2600rpm - full throtle - better setting to climb.

Tests under 115ºC water temp. oil temp under 95º - maximun ºC permited under emergency purpose.

[bongodriver]

Temperature and pressure default, default settings and weather...

Actually if you want a good comparisson to the flight manual data then it would be worth creating a quick mission with a parameter changed which brings atmosphere to standard, look for Breeze/Thermal factor in the mission parameters in FMB and set it to 0, if the performance is off under those conditions then we know there is a problem.

[Crumpp]

Originally Posted by Blackdog_kt

Watch your language...

On the topic at hand, going fine pitch/high RPM while flying in low-density air decreases performance after a certain point. The air is "thin" so you need to coarsen the pitch (lower RPMs) to get a sufficient bite of air, otherwise the prop just spins around really fast without pushing the needed amount of airflow.

It's modeled the same way in 109s by the way (you get better performance if you drop your RPMs a bit at higher altitudes) and it's one of the first things i noticed and really liked in the sim.

That is one of the details I really like about the sim too.

The best thing is the mindset it forces upon a player. You have to keep a scan going even during a dogfight and above all "fly the plane". That fact alone makes it a better simulation than anything to date.