The Dark Side

I just got my Parkzone BF-109 plane. The latest addition to my livery. Hopefully, it will be nice enough this weekend to fly it while I wait for a replacement fuse for my Easy Star. I have been very happy with my T-28, and really would love to get a F4U corsair as well. These foam warbirds from Parkzone are really pretty good planes.

Update: (10/30/2009) I finished getting it all ready tonight, which included getting the CG set for the heavier 2650mAh Turnigy lipo and putting the optional flaps in and getting the Hitec Neutron 6S in and everything trimmed up and all the throws set. Everything I read (plus flying the simulator) says this plane really lands a lot better with the optional flaps. I cut out less flaps from the ailerons than it indicated (about 5" less), just to get more aileron control. If I end up needing more flaps, I'll cut in-board more and try to have that hinge down like I've seen a lot of folks do. I noticed that you could put the gear in backwards, which would have a less forward rake, and make it a lot more unstable. I wonder how many of the folks on the RCGroups boards have put them in backwards that are having so much trouble with nose-over landings? AUW was 39oz with the 2650mAh lipos (about 4oz heavier than the stock 1800mAh lipo). Will try to maiden her tomorrow, if the weather is fitting.

Update: (10/31/2009) Well, went out to maiden the plane today. Ran the eLogger in it and triple checked the throws and CoG. Things worked fine and seemed right. Throttled up slowly and was ready with right rudder/aileron for the tendancy on this plane to twist/torque roll left. It did want to do that, but compensated fine for it and I was in the air. Needed some minor aileron and elevator trim and got it coming in nice and slow, and seems nice and flat. It wanted to roll left with full throttle compared to slow trim, but probably just the fact of the torque. Rolls were AWESOME with this plane. It actually keeps a very nice straight line through the very responsive roll. Flew about 5 minutes trying some minor turns and approaches, and it was great. Then decided to try a loop. Bad idea. It pulled a tight loop and immediately flipped over on its back and twisted and I think the elevator (at least one side) stuck in full up position. Flipped and rolled and couldn't recover it at all. Full speed nose into the ground. Poof! Well, wing is fine. Prop is toast, as is the spinner. Sheared the fuse in 2 places and the canopy was broken. Think it will be pretty easily glued. Have to look closer to the control rods to figure out what went wrong. Nothing seemed wrong with the full throws I had on it when checking on the ground, but something sure died. Bummer.






Update: (10/31/2009)Well, figured out the problem.

EVERYONE CHECK YOUR CONTROL HORNS BEFORE FIRST FLIGHT!!!!!

I got everything glued back together and back in shape. No one had a spinner or cowl, and I got lucky and got the one and only 3-blade prop at one store. So, triple checked everything (throws and control rods were all tight) and while the body is a bit weak/flexed in the center where the canopy fits, it all looks mostly pretty good. Considering.





Anyway, it was still pretty nice and calm out (though cloudy/overcast, which makes the orientation on this plane really hard to pick out). So, I ran out real quick to fly before the little ones have to go trick-n-treating. :)

Took off, and the CoG was a little back, because of the missing spinner, I think, but it was flyable. Just really touchy (you know how bad flight characteristics get when you are tail heavy, slow flight is ugly). But, keep the speed up and it can compensate, just not great trim for various speeds.

Anyway, got it way up, and tried another full elevator loop. Damn thing snap rolls to the right. I don't mean tip stall, it is a full aileron snap roll. OK, recover with subtle elevator control. Bring it in and land. Great landing (the flaps really help a lot). Check how throws look. Good. Body isn't twisting or anything. Lets triple check PMix's. Hum...well, I have flaperon's from my T28 pgm I copied on, but it doesn't do anything with the dial at dead center (BAD to use dial since I'm Y-connected into ch4), ok, turn that off. Hum, I also have a 5% flaperon mix for elevator. OK, that might be it, since enabling the flaps actually just makes the ailerons turn with the Y-connector. OK, turn that off, but before I do, just watch real close. Hum, full up elevator and the ailerons can't even hardly be seen to move, but they are maybe 1mm at max elevator. Ok, lets give it a shot!

Moved CoG forward by pushing battery all the way up. Take off and it is MUCH better behaved for slow flight. OK, get up high and try full elevator loop again. Damn! Same thing, snap roll hard to the right. Try with power off and on, no difference. Watch it close and can't see that the tail is really flexing or anything. At this point, I'm not sure what is going on, but if it looks ok on the ground on the throws, it must be tail flex or something. Finished off the battery and tried an outside loop. Hum...interesting. It snap rolls to the left on outside loops. Sure seems like an elevator PMix, but.

As a final check when I bring it in (another good landing and roll out...make SURE you guys are bending the landing gear out infront of the LE of the wing each time...mine tends to bend back after landings in the rough field and on pavement), I try full up elevator sitting on the ground and start pushing on the control surfaces. DAMN IT! the left elevator can be pushed straight level without much pressure. Start looking closer, and the control horn is super loose. Tighten it down a LOT more, and now it is pretty snug, but it still doesn't look like it has great wide leverage with the pretty small surface area and the foam is pretty smooshy right there. I think I need to CA glue it to get some rigidity. But that is 100% the problem and cause of my maiden flight crash.

So, everyone, please triple check your control horns. On this elevator design, with two separate control horns, it is EXTREMELY dangerous if both are not tight. On a normal single horn elevator, the worst that would happen is reduced throws and responsiveness. But with twin horns, if one is weak, it will flip your plane. Sigh. Hope this helps someone else.