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Old Aug 04, 2011, 08:54 AM
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Old Aug 06, 2011, 01:25 PM
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USA, CA, Oakley
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Whats the best way to test balance in the air on this thing? Seems like mine wants to pitch up when coming off the throttle. I'm currently balancing it at the rear of the receiver cage on the ground.

I've also removed the retracts after a few collapses on landings. Seems to fly better without all that added weight. Landings are a real challenge now as it glides far and fast coming in.
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Old Aug 06, 2011, 01:53 PM
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I've had issues landing mine (sans gear) as the nose wants to tip high once the throttle is chopped right before the flare point. I keep a little down elevator on my final approach to offset this nose-tip tendency. I'd rather deal with a hard landing on the belly then a vertical orientation on flare, landing very unceremoniously on the elevons! (Happened twice!)

This is a tricky bird to get down on all phases due to its very unique elongated fuse and short delta configuration. Once you get the CG just right, and understand precisely how to fly her, she will reward you like no other plane in your arsenal.
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Old Aug 06, 2011, 02:32 PM
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Arlington, TX
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Quote:
Originally Posted by hackdroot View Post
Whats the best way to test balance in the air on this thing? Seems like mine wants to pitch up when coming off the throttle. I'm currently balancing it at the rear of the receiver cage on the ground.

I've also removed the retracts after a few collapses on landings. Seems to fly better without all that added weight. Landings are a real challenge now as it glides far and fast coming in.
Roll it inverted to find out how much forward stick is required to hold it level. It shouldn't take more than about 1/4 stick. If it takes more, it's too nose heavy. If it's neutral, it's balanced just right. If you have to pull back stick, it's tail heavy.

RJ
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Old Aug 06, 2011, 02:59 PM
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United States, FL, Sebring
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there could also be a thrust line issue. If cutting power makes the nose rise, it's entirely possible that an alteration of the exit point of the thrust tubes needs to be looked at. (raised). If the exit is placed too low, it pushes the nose down under power and typically someone trims the plane based on that. Then when the power is cut, the nose rises. The opposite can hold true as well. If the exit is too high, cutting power makes the nose drop as under thust the nose is being pushed up (tail being pushed down). A little experimentation might be in order to determine if engine power on /off affects pitch.
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Old Aug 14, 2011, 08:53 AM
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DTW suburbs
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2nd flight video

finally got the SR71 up and on video,

http://www.youtube.com/user/skeeterz...14/c4qcrEtypjg
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Old Aug 14, 2011, 09:03 AM
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United States, FL, Sebring
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Quote:
Originally Posted by bmg50 View Post
finally got the SR71 up and on video,

http://www.youtube.com/user/skeeterz...14/c4qcrEtypjg
Nice.
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Old Aug 14, 2011, 10:32 AM
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Maple Valley, WA
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Nice job. Looks like you have a good understanding on how she's meant to be flown. Minimal wing rock, nose forward, goose that throttle on low passes...Very smooth liftoff and landings. Love the orange orientation trim as well!
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Old Aug 14, 2011, 01:16 PM
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Exit 4, South Jersey, USA
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Decent!
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Old Aug 14, 2011, 01:33 PM
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Arlington, TX
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I'm morning the demise of my SR71. I crashed it again on Friday and this time I think it's terminal. It ended up in 3 large pieces and several smaller ones. Haven't inspected the electrics yet but, they "look" OK (fans still have all of their teeth, etc.).
Takeoff was much better than the first attempt. More power and authority ...she climbed out well at full throttle. However, I again had the nose-heavy issue even though she balanced out fine on the machine.
I remember thinking that she lacked the speed. I must have done something wrong during the rebuild ...probably a mistake in the thrust tubes. Handling was twitchy but, not unmanageable. I was trying to fly her and trim the nose up at the same time and on my 3rd lap around the field I lost control at low altitude. Totally my fault. If I had more altitude I think I could have saved it.

I haven't decided if I'll order another airframe. It was a fun project and a good learning experience but, I think I'll leave this Blackbird too better pilots.

RJ
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Old Aug 14, 2011, 01:38 PM
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It's funny on this one. A lot of times it seems the maiden goes OK but it's the subsequent flights that do you in.
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Old Aug 14, 2011, 02:25 PM
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DTW suburbs
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its stock BH ESC/fan power set up but the tray area was carved way open length and width to fit a large 3700 3S pak and keep the cg right. That helps a lot i think, plus all the info this thread provides, the whale tail mixed in with elevon plus rudders i think help this plane.
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Old Aug 14, 2011, 02:46 PM
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I don't know what you guys are complaining about. I've only gone through six airframes.
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Old Aug 15, 2011, 09:47 PM
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Sacramento
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Quote:
Originally Posted by bmg50 View Post
finally got the SR71 up and on video,

http://www.youtube.com/user/skeeterz...14/c4qcrEtypjg
Well done! Nice job on the landing!
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Old Aug 18, 2011, 04:09 PM
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Sacramento CA
Joined Oct 2009
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Quote:
Originally Posted by bmg50 View Post
finally got the SR71 up and on video,

http://www.youtube.com/user/skeeterz...14/c4qcrEtypjg
Great flying and landing! Typical long roll-out on this plane as landing speeds are a bit higher than normal. And nothing cooler than taxiing back to the hanger after a successful mission...

Joe
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