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FTFC19 Tron Legacy One-Man Light Jet by DamoRC

DamoRC

Well-known member
Mentor
#21
This build makes me happy. I was wanting to it aswell in the future. You might need a dummy tho on the seat to balance it out. maybe I missed something but where do u plan on putting the battery?
Thanks!
In the final model there is a rider prepared (there are some pics in the design thread). I will probably have the rider sit out the maiden to protect his life (and also to minimize obstructions to the EDF inlet). The batteries (2 x 4S 2200mAh) are in the pods at the front of the pylons, this is the only way I can balance the plane.

Your builds never cease to amaze me!
Well, it looks fantastic. So even if the maiden doesn't go well at least it'll look good! Good luck, hope to see some vid of it flying!
GREAT work @DamoRC !:love: At worst you have plans for a rebuild. (for FTFC19:Build-ruary)
Good luck with a maiden. Break some foam (equivalent to break-a-leg)
Thanks guys!
 
#22
Yeah i was gunna suggest that actually. Its hard to tell how big those gun tips are. I know there are stick batteries that might fit but those are a bit old school, or even run a 'aa' or 'aaa' line :p.
 

jaredstrees

Well-known member
#31
He cheated.. Its just black with orange tape... Which is really smart IMO. My planes dont last long enough yet to justify paint.
most of my planes are colored packing tape as well. Honestly, if you want to do it right, I think tape is the harder way to go. You have to do a lot of cutting to make it look great. Paint, while detail work takes skill, is just point and spray with a little masking. At least for me it is.
 

DamoRC

Well-known member
Mentor
#33
Thanks Guys!

Unfortunately - she didn't fly. Twice. Didn't even make a decent attempt - like throwing a rock.

I will post pictures of the carnage with some post crash analysis and a path forward, if there is one.

Oh well, at least I got the trophy pics.:)
 

DamoRC

Well-known member
Mentor
#36
So what's the takeaway? was there potential?
Hard to tell given the rock-like performance today.

As the build finished up it was clear that I was not going to hit my target of 56oz. Ended up at 58-59. The 70mm EDF and tube is only putting out 40 oz static but I though that with a hard enough launch, I could get her to fly at a 0.65-ish thrust to weight.

I simulated the launch last night at home (loaded batts, held her using two small holes in the under side of the wing just at/behind the CG, and gave her wide open throttle). I realized that because the wing is so long, I was hitting myself in the back of the head. "Note to self, hold it high when you launch." The other thing I noticed was that at full throttle she was pushing the plane over (and down) on my hand. It was subtle but reproducible. I checked the EDF alignment and it seemed okay.

Warmed up the thumbs on the Gee Bee R3 and the Diamond and prepped for maiden. Shame to say, on the first attempt to launch I forgot to hold her high and clear and the left wing clipped my head as it went by. So she went down sideways and a little hard. Not too much damage done, one of the battery pods came off and a slight crack in a pylon. Some hot glue and extreme packing tape field repairs and she was good to go.
On second launch I managed to keep my big head out of the way but she flew straight into the ground. I suspect that the edf is pushing her over a little and I can't get her up to speed before reaching zero altitude. Second time l, damage was beyond field repairable but I think I can get her back together.

Question is what to do next. I will check and recheck the EDF to see if I can confirm that it's causing a push over. But even if I find and fix this, I am wary of throwing her back up so underpowered. So I am also considering adding two motors/props to the front of the pylons. For an additional 8 -10 oz weight I should be able to get 30 more oz of thrust which would give me a little over 1:1 thrust to weight. Wings should be big enough to carry the weight.

Just need to think about this a little more.
 

Namactual

Well-known member
#37
Man that sucks, that was such a beauty.

Looking at it, I don't see any reason it would have thrust angle issues. The only thing I can see is maybe since the wings are so much ahead of the fuse, your "grip" CG is well aft of the lift CG. Maybe if held by hand to test thrust feel, slightly releasing your grip during run up would make it drop the nose? I am not saying that is what in fact happening, but just my best guess.

Also the short coupled design would amplify any CG and/or pitch/trim issues.

It will fly, it looks too good not to.

Edit:
Oops, had a reading comprehension fail. I do not see the holes under the wings or how they relate to the lift or thrust CG, but If your grip is below the thrust tube the results would be the same.

I would try moving the CG back a bit and see where that gets you.
 
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