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My FT Delta maiden...

#1
It left the ground under it's own power, so technically it qualifies as flight...
Ready for takeoff.
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Pitches up and yaws left HARD.
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This isn't going to end well.
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As expected.
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Might have a slight thrust angle issue after that landing.
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I swear the CG was spot on, control surfaces trimmed and set to 19 degrees throw with dual rate on (so about 10 degrees max throw). Aside from the smashed firewall there's no damage to the wing, and I was planning to rebuild the power pod anyway. Time to fire up the hot glue gun again and try to work out what went wrong.
 
#2
I ended up with the CG about 1/4 - 1/2" farther forward and make sure you keep some speed. For a beginner plane it was tough to get flying but once I did it was lots of fun. Are you running a 3S of 2S battery? I also found that my original setup with a 1700kV motor and 2S 800 was just too light to be stable. I changed to a 1500kV 24g and a 3S 1300. Flies very nicely now.
 
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Winglet

Active member
#3
Hi Drake,

Sorry about that. It is fairly commonly known that the CG on the plans is WRONG! You should balance it about 3/4 of and inch or so further forward of the CG shown on the plan. Also....very important to set a little reflex into your elevons. (your elevons need to have 4 or 5 degrees of up set in at neutral) All flying wings are this way. I fly mine on 3 cells. I think it would be pretty sluggy on 2. I would use 3 cells and takeoff with about 1/2 power until you get the hang of it.

Quite a lot of airplane for a beginner. I would suggest that you whip up a Flyer and save the Delta for a little later.
Hope you get her going. A fun airplane.
 
#4
It is fairly commonly known that the CG on the plans is WRONG! You should balance it about 3/4 of and inch or so further forward of the CG shown on the plan. Also....very important to set a little reflex into your elevons. (your elevons need to have 4 or 5 degrees of up set in at neutral)
Ahhhh, I thought it was a little strange that I had to push everything so far back to get it to balance - I even flicked through the FT Delta episode to check where they had the battery and simply assumed that my foam board was heavier than theirs, plus I'm running a fairly heavy motor setup: Emax CF2812 1534kv (about 40g), 3S 1200mAh, 35A ESC (overkill). With an 8x4 prop it easily pulls my FT Flyer vertical and cruises on less than half throttle.

I already have an FT Flyer, and although I haven't been flying long I seem to have the hang of it. Having the correct CG would have definitely helped the Delta. Once I finish building a new power pod I'll do what I should have done before this mornings "flight" - a glide test:black_eyed:

Thanks for the advice, hopefully with that and some good 'ole 20/20 hindsight the next flight will be a little longer than 1.2 seconds (but at least it was only a short walk of shame)
 
#5
Well I finished a replacement power pod last night, and despite it being too windy for a proper flight decided to take it out for some straight line testing... and it flew! Maybe only head high for the length of the cricket pitch I use as a runway (22 yards), but with the CG 3/4" forward of the plans and a bit of up trim on the elevons I managed a (brief) stable level flight and only bent the landing gear a little on landing.

Now, the bad news... I can't taxi at more than a crawl without ground looping to the left and when the tail's that close to the ground giving it left aileron will cause it to yaw right, and right aileron will just make it go left harder. Once it's off the ground it behaves itself - wind was coming straight down the runway and by keeping the wings level I landed it about a meter to the right so there's little to no yaw in level flight. To get off the ground I had to get it rolling then punch the throttle before it had a chance to yaw left

My thinking is a little right thrust on the motor might neutralise it's tendency to loop left, and the strange yaw while taxiing is just a result of ground effects and having the elevons almost scraping the ground?

Anyway, thanks for the CG tip - it flew well enough for a novice pilot in too much wind to get it up and down safely so that's a big improvement, and if I can't sort out the ground loops I'll just hand launch like I do with my Flyer.