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Shortround6,once you are dealing with high speeds you have more variables to come out and play with
Drag goes up with the cube of speed.
Your Lift goes up with the square of the speed.
The engine power (as opposed to propeller efficiency) is a combination of air density (not much change in speed) and the RAM effect of the intake and the pressure ratio of the supercharger on WW II airplanes.
Some of this is somewhat academic.
If your plane will only fly at 330mph true instead of 345mph true at 10,000ft due to hot temperatures you aren't going to know it. You are going to be looking at IAS for airspeed and the airspeed indicator is reading the existing air pressure (density). If the enemy airplane is also by 10-15mph from it's "book" figures it is going to take a long tail chase to to figure out the speed difference.
The speed/climb differences at 80-150mph when taking-off and landing are what can kill you every time you take-off and land.
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I have no idea why they figured out the chart this way instead of using 59 Degrees (standard day) but the Army Charts are measured from O degrees C and 32 degrees F. (maybe they figure you know the difference between your boots sliding on ice or splashing through a puddle?). But at just about 92 degrees for the P-38 your take off distance will be 20% higher than the chart shows. North Africa can be worse.
Note that they are only figuring a 10% increase in time to climb compared to the 20% increase in take-off run.
I get that, my observation was, maybe aircraft with a little bit higher wing-loading and a shorter wingspan might have a bit more trouble in thinner air. Not saying that's it so, just speculating.
I know, but a production machine was tested in the as produced condition (where this discussion started). Things like aerials cannon blisters etc would be noted.Spitfires were extensively tested by the RAE in regards to the who what and when and their effects speed, aerials, guns, blisters, ejection ports, rear view mirrors, exhaust types, panel fit and over paint condition and fit and finish where all tested and they had no trouble getting a 20-30mph increase in speed from Mk1's through to MkIX's by incorporating all the above.
Schweik,It's one of those things that after near 40 years of reading about airplanes practically every day, I never really understood this until today. It's quite interesting and I suspect it does help explain why some types did better in tropical environments and some in cold.
When I first read that description of takeoff etc., I misread and thought you were describing the T-38 as a 'performance dud'.
Does the TOLD etc. have the same relevance once you are up high and it's colder ?
Here is another way to thinking about it. The plane flies like it's at the altitude it thinks its at. If you take off from hot, it flies like it's higher than it is (it wheezes sooner). High altitude fields make this worse as your take off performance is even more affected. Take off from cold, the plane flies at the altitude it thinks its at, which is lower than it really is (has more get up and go). High altitude fields reduce this some.I think it's sound thinking. A smaller wing develops less lift anyway, and it stands to reason that in less-dense air a smaller wing carrying the same weight will have more trouble.
Mine wasn't a correction to you, simply an added thought.
Here is another way to thinking about it. The plane flies like it's at the altitude it thinks its at. If you take off from hot, it flies like it's higher than it is (it wheezes sooner). High altitude fields make this worse as your take off performance is even more affected. Take off from cold, the plane flies at the altitude it thinks its at, which is lower than it really is (has more get up and go). High altitude fields reduce this some.
If you didn't have an altimeter / airspeed indiciator but knew how your plane flies / what power it makes and speed that gives. Then you would set 50" of manifold pressure and would expect to see 300 mph at 10k (this is an example). In reality, using those power figures and altitude guesstimates you see less than 300 mph which would lead you to believe you are higher than you guessed. In reality you are at 10k and it's hotter than standard. The plane doesn't know, it makes the power and speed it can given the altitude and the temp.
Cheers,
Biff
My guess in third world countries you will see more accidents due to poor training / decision making.Right, that's why we see more accidents in African highland airports, because while the plane knows what it needs to fly, the pilot still has ingrained patterns which can cause problems.
I guess that "listen to your airplane" is probably some good advice here.
Yes, I stand corrected! Sorry about that, no snub intended! I think Qantas has the hands down best safety record.Easy on. Australian & New Zealand are a long, long way from North America and Europe.
My guess in third world countries you will see more accidents due to poor training / decision making.
Here is an example. I've been briefed but am unable to share details.
There is a reason we have the safety stats we do. Be very very careful the further you get away from North America or Europe.
Drag goes up with the cube of speed.
Your Lift goes up with the square of the speed.
Then perhaps compare the accident rate for the P-38s of the 12AF that operated in the UK and then sent to North Africa in '42.
Two entirely different climates.
you are correct.Does not drag go up with the square of speed also?
Power required goes up with cube of speed.
This severely hampered B-26 operations in the South Pacific. A Navy report from mid 1943 rated the early B-26B with the R 2800-5 engines as having a combat ceiling of 12000' and a max bomb load of 2000 lbs. Take off run was longer than a fully loaded B-17.I think it's sound thinking. A smaller wing develops less lift anyway, and it stands to reason that in less-dense air a smaller wing carrying the same weight will have more trouble.
Mine wasn't a correction to you, simply an added thought.
The problem was that the P-38s used in the Med used different inter-coolers and quite possible different model superchargers (and possible different turbo controls ) over Europe in 1944 than they were using in early/ mid 1943.From what I've read, the -38 acclimated to the Med much better than it did in Northwestern Europe. Is this accurate? The reasons I've read refer to engine cooling and altitude flight. If you've got any insights I'd love to hear them.
The problem was that the P-38s used in the Med used different inter-coolers and quite possible different model superchargers (and possible different turbo controls ) over Europe in 1944 than they were using in early/ mid 1943.
I fixed the above dud comment to include the Mighty Bronco.
I suggested comparing the operational records of the 12AF P-38s groups that were first operating in the UK before being transferred to North Africa in 1942, because it would have the same aircraft piloted by the same guys.The problem was that the P-38s used in the Med used different inter-coolers and quite possible different model superchargers (and possible different turbo controls ) over Europe in 1944 than they were using in early/ mid 1943.