warchild
Charter Member
progress notes..
esterday i was working on smoothing out the curves for the control surfaces to make controling the aircraft more precise and closer to realistic. I say closer because we only have anologies to work with from pilots and observers. I believe i have done ok with them but time will tell.. Today it was about props and getting them tuned to match the ones used on the p-61. The P-61 actually used one of two props. At first they used a Hamilton Standard prop wuth a faurly cinventional shape to it, but it was designed for and later used the Curtiss Electric prop whuch had a paddle shape out towards the tip. That paddle shape provided a percentage of higher power and therefore speed at higher manifold pressures. Our P-61 has been plagued with slow acceleration rates. That meant that even though we could engineer the drag and other aspects of it to take off with flaps in the proscribed distance, without flaps (such as in a scramble takeoff ) it would take over twice the length it should have needed.. I'd been baffled by that till this morning when i was talking with delta558 when it all fell into place.
The "paddles" on the tips of the propellers cause it to grab much more air when the pitch of the prpeller is advanced above 37 degrees, so i focused on changing only those curves in the table, the ones between 45 degrees and 60 degrees. this resulted in is a clean takeoff distance 9 no flaps 0 of about 2500 feet at 137 mph. Standard flaps ( 20 degrees ) causes the plane to be able to take off in a little under 2400 feet, and with 45 degree flaps, yoy can take off in a little under a thousand feet. Full flaps a little less than 900 feet..
I also noticed while flying around that when you banked the nose would yaw upwards instead of fall like its supposed too. Guess i was blind or something. I fixed that as well tonight..
Induced drag may be a bit high. she seems to be falling off her speed a bit fast in a turn, but that may be my imagination.. I mean, i can see a GA aircraft losing speed like that in a turn because it isnt designed for the purpose of fighting, but a fighter relies on the ability to maintain energy to some degree through a turn in order to maintain maneuverability, and this plane especially so. Part of me wants to think that momentum alone would help pull it through the turn, not to mention those big engines of hers.. She ways several thousand pounds mor than a B-25, and yet is only one man wide, carries only three crew, and no bombs. Well, at least no bombs during the earlier periods of her usefulness.. Shes a 30000 pound freight train. She shouldnt slow down quite so soon.. At least, i dont think she should.. maybe i'm incorrect though..
Work continues
..Pam