The flying monkeys got me...

Helis and fixed wing

AMA 957918
IRCHA 4345
AMA Intro Pilot Instructor

Monday, April 9, 2012

Flight of the Sbach: HOLD ON!

I have detailed my ongoing Sbach adventures and the build of my second one. Yesterday I got to take her up on her maiden flight. Conditions were very good. There were cross winds of 5 mph or so, clear skies, no turbulence.

I am flying her quite heavy. Her all up weight is 2.75 lbs, 1250gms. She is a 450 class airplane that is designed for up to a 480 motor, and her designed AUW is less than 2 lbs, around 900 gms. My first one had that motor and flew well (she died when for some reason she could not pull out of a dive. I think the 9gm servos could not pull her out of the dive as I was flying her with a 480 motor but this large 4S battery, so I am going with mini servos on the rudder and elevator with more than double the torque). I have her equipped with a HeadsUpRC Power 15 Sport motor behind a Xoar 10x5 electric wood prop from Graves RC. I power her with a 4S 3300mAh 30C battery, and a 40A ESC/L-BEC. She has two Fusonic mg-d-9g aileron servos from wowhobbies and JR MN-48 mini servos from Horizon Hobby (I prefer faster Hitec HS-82mg servos, but I have two of these MNs so used them. They are fine, just a bit slower and with nylon gears). I found a way described in my build post to get the wheel pants to work, and they performed flawlessly. They look very good! Check out the build post in the link above. My DX8 is programmed with flaperons, 30% expo, and rate sets of 30, 50 and 100%. I found she flew quite well on the mid rates. I usually fly 25% expo and may dial her down, but she seems pretty happy as I have her set up.

She takes a little more runway on takeoff, and sinks fast, but she is incredibly agile and fast! She had no problem with the cross wind. In the vids I am flying some serious aerobatics and she handles it all on 50% rates! The frame shows no stress issues. On full rates she rips the sky apart! She is stable, stops moves on a dime, but is so quick to respond that a moments inattention will end in disaster. In the vid there is one moment where I have to duck down under Vinsen's Revolver, and come withn a foot of the ground. Big time pucker factor, but she pulled it off.

I didn't film the first flight as my camera fell off my noggin. I didn't bother with it on the next two flights either. The video here is of the fourth flight, I think. I had evaluated her in takeoff, fast, slow manuevers, and light aerobatics, stall, approach and landing. In this flight I took her through rigorous high and low speed aerobatics. She is on rails and required almost no trimming. I planned the last flight to be an evaluation of the flaperons, but, well, the ESC failed and I had to deal with an inflight emergency where she glided marginally downwind with one heckuva sink rate.






  1. Congratulations! She's really beautiful!

  2. Hey!
    Nice job with your Sbach!
    I would suggest you move the cg a little back to reduce the load on stab and wing, did it on my Sbach and it really loosend up in the sky and glides much better now!
    Did that on my 46-size F3A-plane aswell nad it stopped stalling it`s stab in loops and pullups :)
    Best regards Johan Ohman, Sweden

  3. Thanks, Johan! I have not had a lot of luck with her... I have tried to lighten her flying 3S, but she is anemic, so going back to 4S. She ad been a bit forward on her CG. ai will pay particular attention to moving it back!

  4. Hi Ken!
    I just came home after flying my Sbach again, it still need the cg futher back, it flyes nice and glides really good now but it still jerks out from tight loops and pullups! I have a Turingy Park 480 with Birdie 30A and new 2250 3s 35C packs, I tried with my old 3s packs but I didn`t get the needed power/amps from them so I got new ones and now it hovers and have nice vertical :)!
    I have the pack tight against the wingtube, planning to build a ramp so that the battery can be moved back over the tube, the intruction says cg to be 60 mm from LE at fuse but I have now aprox 70 mm and I want it even futher back!

    Best of luck!