Scale Build-Off - Mignet HM.14 Flying Flea

rockyboy

Skill Collector
Mentor
I think in the plan they suggested using the 4 tiny screws, but I ended up dropping 2 of the little buggers and lost them in the clutter on my shop floor. So I switched to using some of the extra carbon fiber rod. I don't think either way is particularly right or wrong - so long as it stays on the plane it's all good. ;)
 

rockyboy

Skill Collector
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Pictures and video coming soon, but initial results with the fully covered model were not positive. :( Just too much weight I think.

It made it off the ground a couple feet hanging by the propeller - which looked like a cool 3D maneuver but I think ate battery voltage quick. Once voltage dipped after a few moments, she came back down a little hard. I pushed my luck for one more takeoff, and it came back down a little bit harder. Not a great idea.

Since I fixed the previous problem of having propellers fly off by melting the prop hub onto the motor shaft, the prop stayed firmly in place when it hit the floor this time. Instead, the motor came flying out of the mounting bracket. Overall, I think this was a good thing - no damage to the motor bracket or airframe or prop. However, I didn't have nearly enough slack in the wire and it ripped the positive connection right out of the motor. Luckily the motors are only $3 each, and I have a spare :)

So my next steps are to replace the motor, remove the covering from the bottom of the wings, and start cutting out some balsa to reduce weight as well. I have a little digital scale on order, and once it arrives I'll start measuring the gram-by-gram dieting progress to see what it takes to get her back to performing well. Cause I'm not giving up on the new good looks. :)
 

rockyboy

Skill Collector
Mentor
Here's the video of the entertaining little 3D hover.


I'm going to try pulling the covering off most of the model, carefully removing sections of sheet balsa, and then recovering. I have a little digital scale on the way to help me figure out how many grams I'm at and make a target for the diet plan. Thankfully it's such a small model I have plenty of covering left in those little folded packets.

Oh well - such is the way of modeling. Some days she flies great and that's fun - and some days you get the chance to practice repair skills which can be fun too. :)
 

rockyboy

Skill Collector
Mentor
After more research and some weighing on the scale, I think my problem might be more related to the loss of the under camber wing profile than the extra gram and a half added with the covering. So in the hopes of keeping her pretty without a complete rebuild I've stripped away the covering from the bottom of the wings and am eagerly waiting for either the next indoor flying event or a really calm day.

Neither one seems to be coming soon enough however - and I just don't think this thing is going to fly in 15-20mhp gusting winds. So I wait.

IMAG2300.jpg IMAG2301.jpg
 

DarkFire

Member
Has it been blowing 20 mph winds for the past 10 months or did you give up on this thread? I want to see a flight video! I'm also interested in this model because i'm looking for a cheap, good-ish, unique model.

Dark
 

rockyboy

Skill Collector
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Resigned to this being an indoor model - and for various reasons haven't made it to a single indoor flying event since last spring. Which pretty much sucks.

However, I'd rate this model as very cheap, pretty unique, and sort of good-ish if you keep it very very light.
 

Snowblind

Propeller Balancer
As far as what I understand about airfoils, the loss of undercamber was basically the only problem, It drastically reduces lift and drag thus making the plane require, as well as more easily reach, a much higher flight speed. If you were unable to get it to nose down and speed up, it may have been tail heavy.

That was a huge change in airfoil, you should expect a huge change in it's flight envelope across the board.

All that said, I loved the way it flew in the first video with the undercamber, regardless of how much I wonder about how fast it would fly with flat bottomed wings.
 

DarkFire

Member
Is the motor you used relatively similar to the Champ? I've got a board with linear servos that I would prefer to use in case the board sold by Banggood can't bind to my Dxe
 

rockyboy

Skill Collector
Mentor
I think you're right on point about the airfoil @Snowblind - even after removing the covering from the bottom, I still don't think it will fly quite as relaxing as when it was bare. Going to need more airspeed cause of the weight.

And yes, using full Champ electronics is a perfect fit, motor and board. I had to shoehorn in the other board - a linear servo one would have lined up the control rods much better.
 

rockyboy

Skill Collector
Mentor
I finally made it to an indoor flying event this weekend, and ran into a new problem. The motor pulled right out of the mount! :black_eyed:

The 3d printed pillow block style motor mount I made is just slick enough against the motor, and the balsa it pushes the motor into must have compressed just a little bit - cause the motor wiggled itself free twice!

I really don't want to glue this motor in if I can avoid it - so I'm thinking I'll reinforce the balsa with a little CA glue, and then glue thin strips of 400 grit sandpaper to the mounting surfaces to create a solid grip.

Back to the workshop for this one! There is a 6 hour indoor flying event coming up in a couple weeks and I really want this one in good shape for some soaring again!
 

Joker 53150

Mmmmmmm, balsa.
Mentor
Since it's such a light-duty motor, how about something similar to what is done with the UMX micro planes, where they use silicone sealer to hold the parts? If you had a rough enough surface to work with that may be all you need, plus you could always remove it in the future if necessary.
 

rockyboy

Skill Collector
Mentor
That's a cool idea I hadn't thought of... pretty sure I've got an opened tube of silicone bathroom caulking hiding somewhere...

Thanks!
 

rockyboy

Skill Collector
Mentor
My opened tube of silicone dried up and needed to hit the trash can, so I went with a small strip of 400 grit sandpaper CA'd to the motor mount. With the motor tightly held in place, I took her to an indoor flying event this morning and she flew great! Multiple times even!!

On about the third or fourth battery, I landed a little rough and the following flight she didn't behave right - went right up into a hover orientation on takeoff, and then came down hard on the rudder. Snapped the vertical stabilizer cleanly off the body.

So time for a little CA and a close investigation to see if there is any other damage or shifting going on. I had about 10 combined minutes of flight time on her today and very much enjoyed circling her around the gym. Need to get her back in shape for the next indoor event!