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Author
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Topic: Speed Bleed
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Tailslide
Pilot
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posted 06-06- 12:31 AM
   
Flew online with wolfhound, Mk, etc tonight.. I notice the 190A4 bleeds speed waay faster than the Spit V in a turn.. also way faster than the p47. I have no info on speed bleed.. right now it's pretty inconsistent between planes how can I check this against real life? TS
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Patch It! TS Aircombat
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Zurawski
Pilot
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posted 06-06- 09:14 AM
This is a good question ...I found with the P47 ...That if I "fudged" the surface area of the fuse, it could neither acheive operational alt. nore top speed ... (Right now the fuse surface area is "spec-on") ...  I'm not entirely sure what we are missing ... but surely we can't really model parsitic drag from the canopy ... radiators ... external store mounts ...paint ...etc. Michael? ... Your thoughts as to what me are missing/not seeing? [This message has been edited by Zurawski (edited 06-06-2000).] IP: Logged |
Tailslide
Pilot
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posted 06-06- 10:59 AM
I think the speed vs altitude thing is because of openplane not modelling horsepower change at altitude. Some pilots manuals I have list different horsepower values for different altitudes. I fudged the fuselage drag on the yak to get the right speed at sea level and at 15000 feet but the engine still has alot of power up high so its performance doesnt drop off. Re: speed bleed, we almost need someone who's flown these things for real to help.. TS IP: Logged |
biggels3
Pilot
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posted 06-06- 12:28 PM
my dad could
he has a good load of flying time in theis old warbirds
what do u want to ask him.------------------
scramble!scramble!scramble! "i have to go biggels3 out"
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Tailslide
Pilot
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posted 06-06- 09:15 PM
email on the way soon, I'll try and keep it under 20 pages !
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Gecko
Pilot
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posted 06-07- 06:15 AM
I believe that if you match the flight performance envelope correctly(sustained g vs. speed/altitude), the correct speed bleeds will come naturally. The left side of the 1g envelope for example represents the lift limit, which determines the behaviour at high AOA, while the right is associated with engine power, and these are the two sides that need to be matched best in order to get the correct aerodynamics and performance parameters. The speed bleed should turn out to be rather correct by itself.Or so I believe. -Gecko =FC= IP: Logged |
Sv
Pilot
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posted 06-07- 09:05 AM
Tailslide,I have come to the conclusion you have seemed to reach... what is real? Without stats for E bleed or turn rate, how do you continue work on these aspects of the FM? It seems that waht you don't know and try to "create" gets carried away fast. Kinda like when I try to cook (I am a bad cook) - I pout too much of everything in... yummm, sugar, more sugar! nutmeg... yumm, more nutmeg! heheh Also Gecko, what about the airfoil? Energy bleed in turns can be hacked right now by setting how much the drag increases related to AOA and at what AOA the drag starts to ramp up as well. It seems like OpenPlane was built so that you would enter the "real" airfoil data and it should work, but if you get stuck getting things to spec then it seems like you must hack the airfoil, even if just ever so slightly. Of course I get carried away and and up with a Frankenstein of a plane  ------------------
-Sv =FC=
WWI in SDOE!
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biggels3
Pilot
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posted 06-07- 09:12 AM
yeah thats why the p51 looses less speed in a max rate tern then a spit because the p51 has a laminer flow wing. ------------------
scramble!scramble!scramble! "i have to go biggels3 out"
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Gecko
Pilot
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posted 06-07- 09:28 AM
Sv,unfortunately I am not that familiar with how OP works (I always say to myself I need to get into it but never do). Usually entering the airfoil data should give the correct behaviour of the speed bleed and other parameters. There is just the issue of knowing the correct airfoil parameters, and how the airfoil cross section interacts with the shape of the wing, which, without full aerodynamic calculations is impossible to do. Also, the OP engine probably does not take into account the interactions between all aerodynamic properties of its separate parts. That's why some adaptations of the airfoil parameters should be done in order to better approximate the overall aircraft, not just the separate airfoil. In principle, after the fitting procedure, you would end up with a very correct 'effective airfoil' for the plane's wings. -Gecko =FC= IP: Logged |
Tailslide
Pilot
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posted 06-07- 10:42 AM
Actually I was flying the 190A4 last night (the other night I was flying the spit) and it doesn't bleed speed any more than the p51 or 109. The spit and p47 seeem to me much better than the 190,109,p51. There are too many factors that effect speed bleed to say 'we plugged in all the right numbers lets just assume it is right' TS IP: Logged |
Tailslide
Pilot
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posted 06-07- 10:47 AM
For example, with the same airfoil, if you decrease the wing efficiency (airK) you will get more speed bleed. If you move the weight forward a bit and increase elevator travel a bit you get more speed bleed. All with the same airfoil. Considering one of the hacks that appear to be done on the airfoils to keep them from stalling was to alter drag at the stall point, we can't be sure about those either. TS [This message has been edited by Tailslide (edited 06-07-2000).] IP: Logged |
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