Hand launch problems. Latest problem child was a Hobby King Raptor and launch. On a good day, it will kiss the ground on a launch, others it just hit’s the ground. A search on the web, found everyone had that problem. One solution was to change the angle of the motor. I bit, and shimmed the motor. Can’t say it made it any better, or worse, but looked like it was headed for the reject pile. The problem - it flew great, once you got it up. Another solution was landing gear and ground take off. Nose can’t rotate As the gear prevents it until speed it built up. Didn’t want the gear. This thing came with ailerons, and the option for flaps. I did the flaps. Test flights, showed a radical nose pitch up, with a lot of flaps down. Solution? Yep! Problem is in the design. Easy Star has it, Bixler, you name it. Motor is on a pylon, above the wing and horizontal stab. Air flow from the prop, misses both until it is up to flying speed. Motor wants to pull the nose down, and there is no air flow over the flight Surfaces. I gave some thought to hacking the tail and making it a “T” Tail. Never got to it. Give it a try. Flaps down on hand launch. Just remember to retract them Once you get up to speed. ( they steal air from the tail feathers and things get ugly ) If you don’t have flaps, try flapper- on, or radical camber with the ailerons. Just do your experiments way up there., until you see what you can get away with. Anything that will pitch the nose up will work. Love it now! It thinks it is a glider with the motor off. Full power, it is fast. Time to load it up with bigger batteries, camera and gadgets. LEM
I've had several planes that seem to want to fly into the ground on launch like you're talking about. I've also had some planes like my Stryker that have the same basic problem only because I'm afraid to turn on the motor until it's well out of my hands (I really like my fingers!). All I've ever done to fix the problem, and it works very well, is to program a mix on one of the TX switches to give me extra elevator during launch. I flip the switch on to throw it and as soon as I get both hands back on the transmitter, I flip the switch off. Doing this, you can give it any amount of up elevator for the launch and get rid of it a few seconds later when you don't need it. If you had three hands, you could do this without the mix, but I only have two so this is what I do. It probably sounds to simple, but all I can say is try it. I've never had a plane it didn't work on. I even set this up on the Bixler-2 I just got to make life a little easier on launch. I'm sure the flap solution works well to, but then most of my planes don't have flaps and everything out there has an elevator. ...Tiger
Good point! Another thing I seem to have over looked, it appears to be power related. Perhaps if I just throw it with no, or little power, and then bring the power up slowly? Something else to try, but it may go out the window when the weight starts piling up. I'm just a bit reluctant to flip switches. The sticks and sliders are more forgiving. I seem to be gifted with the ability to hit the wrong switch at a bad time --
Yep - When you load it up with FPV gear all this gets a little more challenging. I know what you mean about switches, but in this case, just be glad you have them. Don't know what TX you have, but I fly Futaba 10C's so I have sliders, switches, knobs, and whatever. Let me tell you how I do it in a little more detail... I'm right handed so I throw with my right hand. That means my hands are off the most critical controls (Elev/Ail). If you're like me, if someone throws for you, I always have a happy outcome. That's because you have all the controls in your hands at all times. The trick is to find a substitute for your right hand while you throw and then scramble to get your right hand back in position (before the crash). So... What I do is always use a switch on the left side of the radio as close as possible to the throttle lever. I also try to use one of the long handled switches to make things more foolproof. If all your switches are the same length, you can put a plastic sleeve or a piece of tubing over the switch of choice. I always program my radio so that in the default flight mode ALL my switches are forward (keeping things simple). When I'm doing the hand launch, I pull that top left long switch down to lift the elevator. Your left hand is already stable on the radio so after the launch it's not at all awkward to flip that long switch handle back up to the default (no elevator boost) position. Another thing I should mention that I didn't go into before is that when I'm setting the TX up to do this, I program the elevator (boost) travel distance with a knob. That way it's easy to tweak in the perfect compensation during the first couple launches. On some planes I leave that control on the knob. On others, where I don't think I'll ever want to tweak it again, I take the travel adjustment off the knob and give it a fixed amount equal to what I liked while using the knob. I know some guys with other radios don't have all the flexibility that I have with the Futaba, but still the basic scheme works for them. Using a slider like you mentioned has the advantage of not having to take your hands off the throttle (nice), but I like the switch because the function is either ON or OFF and there is nothing in between to screw you up like if you didn't move the total travel of the slider. I also do a lot of other things with my slider so I wouldn't want to give it up just for launch compensation. I think if you try doing the switch the way I'm doing it, you'll find it's pretty convenient. Works for me anyway! Glad you did your post here. I think it's really nice to share these kinds of ideas with other guys. I wish everyone did that. There are a lot of clever guys doing clever things out there that make the hobby more fun. Not all ideas work for everyone, but kicking things around like this always seems to stimulate people to try new things. ...Tiger
Update on the Problem Child. Great day to fly today! Old friend and perfect weather! Solution for the bad hand launches, was really quite simple. Wasn’t bad design. Just the wrong mind set. More isn’t always better. Full power on launch was my bad idea. With that behind me ( somewhere in there, the brain started working ). At full power, before launch, I could feel the radical down pitch in my hand. Don’t go there! I simply spooled the motor up, until I felt it, backed off A bit, and launched. Problem was gone, and plenty of time to get back on the sticks, and slowly bring the power up. From there. All options were open. Vertical or anything else. Matt suggested I try a ground take off, just letting it skid along the ground. I advised it had been tried, and not enough power, but gave it another try. It didn’t want to move, so I gave it a bit of push with the foot. Bingo! It was off to the race! With, or without, flaps, it was in the air in about 20 feet. No landing gear, No wet grass. I had met the enemy. I was me!
