Scale Build-Off - Mignet HM.14 Flying Flea

[rockyboy]

As a fun challenge that will still fit in my limited plane storage space, I'm going to see how far I can go building a Flying Flea Mignet HM.14 indoor flyer using the el-cheapo Banggood $15 kit. http://www.banggood.com/TY-Model-NO_7-292mm-Wingspan-Wood-Park-Flyer-RC-Airplane-KIT


(Image from Banggood)

In addition to the HM.14 there were several close variants of the Flea and once I assess the kit components I'll pick a final version to go after from a scale match perspective. In particular I need to plan out the engine area approach as the "out of the bag" kit doesn't match up too well with the variants I've been researching so far. https://en.wikipedia.org/wiki/Mignet_Pou-du-Ciel

And yes, the Steven's Aeromodel S-Pou is a much better looking (and probably better performing) kit and I'll probably do one of those in the future, but I'm pressed for budget and space at the moment so the 12" wingspan of the Bangood kit is a small risk that might be a lot of fun.

I've ordered the recommended electronics, also from Banggood, and will give honest feedback about the shipping, packaging, kit design, and performance. I've seen more than a few horror stories about poor packaging leading to damage in shipping, but I'm hoping for the best here.

By using the recommend electronics I'm also provided with an excuse to get a FlySky radio module for my Taranis. Some days I wonder if my real hobby is customizing and expanding the capabilities of my Taranis, and airplanes are an extension of that.

 

[rockyboy]

Progress!! Problems!! Obstacles!! And neat looking things Created!!

So the package arrived from Banggood before the holidays, a flimsy plastic bag that I was expecting based on the experience of others. I was certainly worried about the safety of the balsa inside...



But the goodies inside were wrapped in a ton of semi-rigid foam. I think it would have been cheaper for Banggood to use a cardboard box than this huge amount of packing.



But everything - balsa kit, recommended receiver, JR radio module, and two motor/propeller packs came out of the bundle safe and sound!



The balsa quality is actually quite good, and the cuts in the plywood and balsa are all very well executed.



So I downloaded the instructions from Banggood and started trying to figure out how to put this thing together. The pictures in the instructions do a good job illustrating how to assemble the airframe. But there are no English words on the page.






So it's now a pretty little plane - but the problems are starting to pop up.




The recommended electronics linked from the website don't match the instructions. I think I can make the receiver work
with a little cutting and bending of control linkages (it's mini rotary servos mounted on the board instead of of low profile linear servos).

But the motor mount is going to be a bit trickier. The kit is expecting one that has 4 mounting screws to attach to the firewall. The mounts that arrived are all rounded and expect a "stick insertion from the back" style instead of screw mounts. So I'm going to try and fabricate some lightweight motor straps for this to avoid a permanent expoxy mount - I would like to be able to swap out a bad motor in the future without cutting away glue.

Also, the pictures in the instructions around the mechanical linkages and wiring leave a lot to be desired - and while there is a fair amount of Chinese writing on that page, it's of no help to me - my friend who speaks Chinese well is out of the country till spring.

So I'm just going to make the rest of it up as I go along.

 

[Joker 53150]

From someone who has built too many Chinese balsa kits, throwing away the "instructions" is often your best choice. Information is often lacking or just plain wrong.

 

[rockyboy]

She flies!!

 

[willsonman]

Congratulations!

 

[Joker 53150]

Nicely done! Are you planning to finish it off with some color, or would that add too much weight?

 

[rockyboy]

Thanks!

I'm definitely interested in adding some color, but I've never done anything on balsa other than iron on covering. Since this is sheet construction, I thought perhaps I could do some sort of paint or dye application - need to do some research on that - any tips would be welcome!

From a flying review perspective, this thing has a surprising amount of power with the $3 brushed motor and gear box. I've never had it over 50% throttle, and usually it cruises in the 20-30% range. It flying surprisingly well for a such a cheap pile of parts - after 4 or 5 flights I had it confidently following the pattern around the gym, and behaving very responsibly with very little stick input. I plan to dial back some of the throws as it really doesn't need very much 'elevator' input - if I'm too heavy on the sticks it can get a bit swoopy.

Actually, given how much extra power this thing has, an ultralight covering might work out just fine.... hmmm....

 

[wilmracer]

Congrats! Wish I could have come out to Westfields yesterday. I'm not much of a morning person on the weekends

 

[Joker 53150]

It's not cheap, but the lightweight SoLite would probably work well.

 

[rockyboy]

It's not too big, so a little covering will go a long way. Steven's Aeromodel has some lightweight covering in little $5 packs that look like they would work well. One of the other flyers at Westfield this weekend had the SA Flying Flea and the lightweight covering looked very sharp. I think I'll be placing an order shortly.

 

[NatefromOgden]

Well I'm pleased to see that yours flies as I have one of these just completed on my shelf and have not had any opportunity to try and fly it. As for the motor, my LHS connected me with a Champ motor and gearbox and it has 4 pins that fit into those 4 screw holes perfectly. So now I'm even more motivated to find time and a place to try and get my odd little airplane airborne.

 

[rockyboy]

Started covering last night - this is my third time using iron-on covering, so there are plenty of techniques I need to improve. That said, this covering job is benefiting greatly from a Mono-kote razor blade guide - the seams look so much better than my last plane.

About half way there now - body is done, working on the wings tonight. I'm a little unsure of the best way to proceed with the wings though. There are only 2 ribs on each side of the wings, and then the two ribs in the center that make the mechanical connection and are taller than the outer ribs.

On one hand, I think the additional lift from covering it across the ribs and creating a flat bottom air foil could be good to offset the added covering weight. But would a flat bottom airfoil really add much compared to the concave shape of the current sheet wing? Or should I just paint the ribs and run the covering on the top only, or up tight against the sheeting on the bottom to save the concave shape?

Oh well - it an always be done twice, right?

Attached is the color scheme I'm going for...

 

[Joker 53150]

It was my understanding that the open bottom of the wing produced more lift than a covered bottom. But I may be wrong...?

 

[rockyboy]

Not sure Joker, but I'll have some real-world experience to compare next weekend at the next indoor flying event here - cause it's ready to go!

Here's the colorized version! I feel pretty good about it for having just a little bit of covering experience. Next steps are make sure it still flys well, and print up some tail number decals and perhaps a name decal as well.

Thanks willsonman for organizing this contest and everyone else participating for inspiration!

 

[Crash and Burn RC]

Wow, that looks really nice, this one could be an SBO winner.
Do you have any flight videos of the covered version?
Colin

 

[rockyboy]

Thanks!! The next chance I have to get this up in the air is next Sunday - will definitely share (good or bad) of how it performs covered.

However, seeing the amazing quality of the other SBO planes on the site, I think my best chance for a win would be if nobody else qualifies in the kit category. Which could certainly happen.

 

[willsonman]

Looks pretty awesome to me! Can you show the underside of the wings better?

 

[BobK]

Looks great! Those wingtips and especially an undercamber wing are really hard to cover..nice job. If you have some covering left over you could try messing with a little hotter temp on your iron by covering a piece of scrap wood and see how that effects the covering and give you an idea of what shrinks out wrinkles and when it is too hot. When covering round wingtips I usually cut the overhang about every half inch making little tabs and folding each over one at a time as I go.

I have had one of those Monokote edge trimmers for years..never could get it to work for me, so you are doing better than me.

 

[rockyboy]

Thanks for the kind words guys!

Bob - I definately need to try your "wingtip relief slices" on the next one - I was able to get a pretty regular crimping pattern by gently running the hot iron back and forth over the cover flap before sticking it down (I know - poor description - words not working tonight). This picture also has a nice shot of the wheels. Same plywood wheels that came in the kit, just took a black and a silver sharpie to them. Much better now.



In this photo you can see the upper wing mounting setup. Without covering, there was plenty of room to slide the two carbon rods through the holes in the wing and pylon. After covering, the back hole was completely under the level of the film. So I had to make some slices, put in the rod, and then patch the covering back up. You can still see the back carbon rod between the pylons, but the ends are nicely hidden away. Now the wing isn't coming off without surgery though...


In this picture you can see how I blacked out most all of the white plastic on the motor mount and gearbox to be a little more "engine like". You can also see the 3d printed black motor mounting bracket I came up with. It's pretty much a "pillow block" half round thing with a screw hole in each end. Held very firm, even through a rough touch and go that knocked the propeller clean off.


And here's a full on belly shot. My fingers are too big to use the tiny laser cut hole in the middle of the hatch, so I made a fingernail cutout on the bottom left side of the hatch instead. Works much better this way.

 

[NatefromOgden]

Rockyboy, after looking at your pictures and description, I have a question about your wing installation vs. my wing installation on the same kit. It appears that you ran some carbon fiber rod through the wing mount pylon and ribs? There was one picture in the instructions that I could not figure out that seemed to indicate the same thing. But when I got ready to install my wing I had 4 matching tiny screws that seemed to be appropriate to use to mount everything, (2 screws on each rib/pylon). Did I do it wrong?

Could you advise on how you did it/how its supposed to be please?