My little frustration build

[techbear]

I was finishing up an FT mini speedster, and I found that I'd really misjudged my CG, and it would take a lot to fix it.

So in frustration, I set that aside and quickly scratch-built a very straightforward little plane. Turns out, it flies wonderfully, so I wanted to share it with you.

 

[techbear]

I used the airfoil shape from the mini speedster, but I cut it as a simple rectangle. In fact, it's as long as a DTFB sheet, and 7 inches wide. Since I didn't want to fuss with polyhedral, I knew I needed to make ailerons, so I cut them and glued on a couple 5g servos to control them.

My fat fingers were incompatible with the deep narrow fuselage of the ft mini speedster, so I wanted to make it wider and shallower. BUT, I wanted to use the same mini power pod, so I wound up making the fuse 5cm wide (inside), and putting in 2 spacers on each side of the power pod. Nice that the DTFB seems to be exactly 5mm thick.

The tail went together quick and easy, just cutting it to what looked right.

I put an angled former into the fuse just to stabilize and strengthen it, and found that (including the spacers for the PP) it was already quite stiff, so I didn't feel the need to add a bottom, or a top near the tail.

After having been so frustrated with the CG I messed up on my mini speedster, I decided to make the wing adjustable. I put panels on either side of the fuse, but only glued to the wing. A saddle. Then I was able to lightly tape it in place, and move it around until I found a CG I liked. Once again, I referenced the mini speedster; I used its CG point, just in front of the wing fold. Once I was happy with the CG, I didn't go back and glue the wing; I just added more tape. Packing tape is SO STRONG (not that I have to tell you).

My fat fingers have such a problem with clevises and linkage stoppers. I'm so happy to use the FT technique of simply bending wire to the right length, and gluing the (centered) servo in as a last step.

I bought the crappy colored packing tape from Amazon a while ago; I wasn't happy. This time I read these forums, and bought from northland wholesale, and the colored tape I got was very good. My decoration isn't beautiful, but was designed to help me with perspective in the air.

 

[techbear]

It flies on rails. Straight and true. Absolutely refuses to tip stall. When I land it right, I pull full up elevator by the time I land.

It doesn't float; when the power's off it wants to come down. I assume that's just because it's not super light. I'm flying with an F-pack motor and a 1300 3cell. That's actually too much power for my taste, so I adjusted the throttle top on my transmitter to 70%. I like to fly like a grannie. No need to punch holes in the sky.

The rudder works fine; I'm just not used to flying 4 channel, and I usually ignore my rudder. I gotta work on that.

 

[techbear]

I'm really interested in figuring out WHY my plane refuses to tip-stall. It turned out very flat and straight, so I don't think it's simply washout. I figure there are 3 possibilities.

1) The turbulence of the servos and servo wires causes inboard stall before outboard stall.
2) The turbulence coming off the fuselage causes inboard stall before outboard stall.
3) The notches on the leading edge tips change the AOA on the tips, making them stall later.

I really hope it's the tip notches, 'cause that's really easy to add to almost any wing.

 

[techbear]

The first time I landed it, I cartwheeled it. There wasn't any damage, except that the back of the fuse folded and creased. I managed to push it back in place, but clearly the back of the fuse is a weak point. I could stiffen it a great deal simply by adding the missing turtle deck. Doing so might make the empennage break off (in a cartwheel landing), though.

But that might be preferable to lasting fuselage damage. Do you think so?

 

[cranialrectosis]

Exciting!, isn't it?

Video or it didn't happen.

Part of the 'fun' is building versions 2 and 3 until you 'perfect' it.

They are never perfect. It's still exciting. You build more and better to make it more exciting. This is what our addiction looks like.

Welcome to the FliteTest forums.

 

[techbear]

I built another, going for lightness. I used 2 servos instead of 4, an A pack motor, and a 600 2s battery. Despite the weight loss, it flies exactly like the first (pictured) one.

I'm gonna bring both of them to Flite Fest East 2018, so see you there!