Doing some heavy fighter performance tests, need Bf110 advice

[Mister Fork]

What performance data are you looking for? (remember, I did the first acceleration tests for Aces High back in 2001).

[Karnak]

Turn rate and radius under various load conditions is the bit I have the most trouble with.  To be honest, I simply haven't worked on those numbers yet.  Climb rates at sea level are also something that I am not sure how to test.  Auto speed doesn't stabilize fast enough.

[Tank-Ace]

find the speed the plane wants to climb at, get upto that speed on the deck, and then hit auto-climb.

[Krusty]

It's not that easy tank ace.. You're still accelerating upward and there is a spike. By the time the spike steadies out you're past 1k and going up... Getting that initial sea level rate of climb is a bit difficult.

[Karnak]

It's not that easy tank ace.. You're still accelerating upward and there is a spike. By the time the spike steadies out you're past 1k and going up... Getting that initial sea level rate of climb is a bit difficult.

Exactly.  Using that tactic the Mosquito VI will spike to well over 4,000ft/min and won't stabilize until nearly 3,000ft up.

[PR3D4TOR]

Stabilize at stall speed on auto climb. Add power slowly. Should eliminate the spike and give you a better reading at low alts. For a sea level reading you'll have to ask HiTech to model Holland first.

[Karnak]

Stabilize at stall speed on auto climb. Add power slowly. Should eliminate the spike and give you a better reading at low alts. For a sea level reading you'll have to ask HiTech to model Holland first.

The altitudes I have been testing at are 100ft, 5,000ft, 10,000ft, 15,000ft and best altitude for the aircraft in question.  Only climb at 100ft presents a problem.

[PR3D4TOR]

Best you can hope for is probably 1000 ft. Hit auto climb/speed and throttle back until you start losing altitude - stabilize as close to sea level as you can (using throttle only), and then add power slowly to avoid the spiking auto-climb usually does, you should get a reliable reading at perhaps 1000 ft.

[Krusty]

It's been tried. It doesn't work that way, because as soon as you apply throttle when climbing you spike still.

[Karnak]

You could apply throttle very slowly, but I bet you'd be well over 1000ft by the time you were at MIL.  WEP would cause a spike regardless.

[PR3D4TOR]

Then HiTech need to model Holland so you can start from below sea level...  Though I cannot help but ponder how you can get past 1000 ft so fast in aircraft that climb 2000-3000 ft per minute.

[Karnak]

Then HiTech need to model Holland so you can start from below sea level...  Though I cannot help but ponder how you can get past 1000 ft so fast in aircraft that climb 2000-3000 ft per minute.

It doesn't stabilize fast at all.  If trying via the slow throttle method you'd have to advance the throttle so slowly that you'd be over 1000ft before you were at MIL.  WEP would be right out.

Keep in mind that many (most?) of these fighters have an initial climb rate of between 3,000 and 4,000ft/min.  The Mosquito VI with 50% fuel and clean has an initial climb rate of about 3,600ft/min, and it is not seen as a particularly stellar climber.

[PR3D4TOR]

How about a quick burst of WEP then throttle back and finally stabilize? Just brainstorming here...

[Krusty]

Again, by the time you even remotely stabilize or can take an accurate reading you're well over 1000 feet.

For now, the best thing to do is guesstimate and mention that there can be errors near sea level. Although if you do every 1000 feet up to 5000, it takes a little more writing down but can give you a better realistic estimate of sea level.

I did some climb testing before and I'd just have the E6B up and a pre-written table on paper, ready for me to just glance at the E6b the second my altimeter touches "1000", "2000," 3000," etc... and I'd write down the value and watch that altimeter again.

Then if you have 1,2,3,4K and you know the lower ones are off, you can kind of predict how the climb rate would extrapolate.

For example, here's a chart I did that way:



You can see how 1k and 2k don't match up, but if you draw a line from the others you can extrapolate where it would realistically end up.

[Stoney]

Turn rate and radius under various load conditions is the bit I have the most trouble with.  To be honest, I simply haven't worked on those numbers yet.  Climb rates at sea level are also something that I am not sure how to test.  Auto speed doesn't stabilize fast enough.

If you use Badboy's Bootstrap method at any load, it will compute rate and radius for you.  Its all about determining stall speed at that weight.  As far as rate of climb tests, you could do an extrapolated value based on altitude, if you can correct for power differences due to altitude.  P-47 might be a good one to test the method for, since it doesn't experience a change in engine power with altitude because its turbocharged.  Then once you can make the method work for the Jug, you could try and apply it to the supercharged aircraft by accounting for power changes due to altitude.  If you really want to get detailed, you could just perform some specific excess power analysis, although this would be pretty involved to get close to accurate.