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Oct 31, 2013, 07:15 AM
Retired CAD guy
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Build Log

36" span Mig-29 9mm Depron


For some time now I have been wanting to try a larger Mig-29.
I have built and flown Otto's Huge 1/2" foam F-22 and F-15 but
I hate the way the Pink foam cuts on my CNC machine.
Depron, on the other hand leaves a nice clean edge.
So, I decided to do a Mig-29 in 9mm Depron and modify it to
be capable of Slide On Ground use.
I started with Tomhe's Mig and deepend the Belly and scaled it up to 36" span.
I have an old tatterd original Tomhe Mig-29 in black depron.
I has a lot of miles on it.
I used Ailerons on it and it would Blurrrrr Roll at high rate.
I'll test this new one for awhile before trying Ailerons.

All the parts were done in 3D CAD and checked for fit.
9mm Depron was ordered from RCFoam.com and after setting up the Cutting files
I used a 1/8" bit to CNC the parts from Full sized 27" x 39" x 9mm material.

There is one already being flown, other than the prototype, by Jack Steinhouser. see pix below.
Last edited by birdofplay; Dec 27, 2013 at 11:15 AM.
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Oct 31, 2013, 07:29 AM
Retired CAD guy
birdofplay's Avatar
Here are some build shots of my prototype build.

I have the spar right on the Motor mount line.
I used a CF blade for the spar instead of the usual CF Tube.
It's 10mm so using it on 9mm depron left some out the bottom. oh well
My thinking is that CF tube is heavy in comparison and a vertical blade
supported in 9mm thick foam should be plenty strong.
This bird will do Cobra flips with ease and on it's club field debut I did a midfield
Cobra which promptly shucked the lipo Pak clear into the cornfield.
The fuse floated down flat and the guys retrieved the pak.
After inspection it was Flown again !
My Velcro Pak attachment simply needed be increased in area.
Suffice it to say that the wing didnt flex, SO I assume it should be strong enough for
anything else I can throw at it.

It's been flying regularly since.
I put a test flight Vid up on Youtube
It was made with a miserable new Turnigy DVR as my old one quit.
The new version has lower rez apparently :-(
I clip it to my Glasses so it's pointed at the subject but I still
managed to get things off center.
Mig29span36 (2 min 55 sec)
Last edited by birdofplay; Oct 31, 2013 at 08:09 AM.
Oct 31, 2013, 07:57 AM
Retired CAD guy
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The Motor mount is angled and glues up against the Spar.
It's High enough to clear the prop on the bottom so Slide On Ground works out nicely.
Oh .. be sure to put the spar in BEFORE the other bottom parts. Duhhhh
I forgot on the prototype and had to do some serious finagling to get it in !

After the MM Plate and hardwood angle glue set up,
I marked and cut some balsa block for the MM supports.
They fit up against the MM and spread the load into
the Wing and Center fuse vertical parts. See pix
Very Solid with very little weight.

It a bit tricky to get that angle against the MM but well worth the effort.

I had intended to try the HK donky motor but the very first flight it SMKOKED.
As it turned out there are some holes in the Bell that were flanged inwards and
they did not CLEAR the WINDINGS !
They burned out by the time it got to the downwind pass after take off.
My estimate is that there were NOT enough spacers on the shaft to allow for clearance.
I'll relieve them before reassembly after I rewind it this winter IF I can get the old windings off easily.
So much for a lightweight motor - C'est la vie !
Last edited by birdofplay; Oct 31, 2013 at 08:56 AM.
Oct 31, 2013, 07:58 AM
Retired CAD guy
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I used Slick Stuff on the bottom for a great slide.
It's a UHMW tape in 3mil thickness.
Much harder than regular ethylene tapes.
It's like the stuff guys put on their saw fences to make them slippery
just a lot thinner.

I am currently experimenting with the idea of simply Taping the bottom in place.
The Slick Stuff is in the Center and only the edges are used to attach the bottom to the sides.
It's working but showing signs of wear.
With the tabs and center fuse for support it's working fairly well.
I may try a different tape the next time around.

Leaving the bottom unglued allows for access if equipment needs service.
On my SOG F-15 I glued the bottom on but found it a challenge to
install and service the equipment. Thus this experiment on the Mig.

I place my Lipo Pak in the Nacelle and adjust it's location to achieve the CG
to be at or just ahead of the ends of the Fins' forward extensions.

More build a little later

Bob
Hoosier Cutout Service
Last edited by birdofplay; Oct 31, 2013 at 08:47 AM.
Oct 31, 2013, 12:27 PM
Allways the hard way!
georgy's Avatar
Hi Bob,

This looks like just the ticket for my long overdue return to my roots... Slot jets!

Some more info on the power requirements please

Regards
George
Oct 31, 2013, 12:55 PM
Retired CAD guy
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Georgy:

I am currently using a Suppo BL-2814/6 and a 7" prop.
I got it from Altitude when they started advertising here on RCG.
I think they are in Utah or Colorado I forget.

The Lipo Pak is a 2700 4 cell .

If you could stand watching the vid, It houls pretty well.
Actually my neighbor has one of my smaller F-15 Slide on Ground models
and we met in the sky a couple of nights ago.
He seemed to think that The BIG Mig was faster although on a fly by
I never would have guessed it.

Must be that Larger seems look like its Slower Effect !

I remember watching C-5's doing T&G's in GA and they "looked" like they were flying at a Walk !


I suppose if you really want slower then leave all the edges square ! :-)

I may be able to put up some more pix soon.

Bob
Hoosier Cutout Service
Nov 04, 2013, 12:17 PM
Retired CAD guy
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Here is another close up on my motor choice.

And then a few shots on the ground before flying on Sunday.

If there is interest I may add Ailerons.

That addition on my original Tomhe sized Mig turned it into a real
AIRSCREW that would roll faster than I can see !

Bob
Hoosier Cutout Service

PS it appears that either the cell phone cam or my Pic compression routine tended
to squeeze the photos in the X axis a smidge ! ? :-(
Nov 12, 2013, 07:54 AM
Retired CAD guy
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After flying this thing regularly for the last coupla weeks
I have decided to make a Modification to the bottom to hopefully improve the
slide on ground performance.

I find that it likes to run flat to get speed on the grass but then PoPs off.
I think it needs a little more clearance at the rear end for smoother rotation.
I have sliced off some of the fuse side from the Prop slot back to where the
round meets the angle at the end.

It managed to snow last PM so it may be a bit before testing gets underway.
Fortunately I did a final season mowing just last Sat.

In other news I have started a 38" span F-22 in 9mm depron.
It'll be a nice companion to the Mig.
I have blended some of Otto's slide on ground F22 and some of tomhe's F22
with the scale up on top of them both.

I also plan a 9mm F-15 version in the near future.

Best

Bob
Hoosier Cutout Service
Jun 20, 2014, 07:08 AM
Retired CAD guy
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My Mig has seen two instances of OUT OF CONTROL crashes due to Orange RX's.
Once with an older satellite type rx and again with the two antenna version.
ALL my oranges are now suspect.
I also lost my SlowBoat with an orange rx .
They seem to work until a few minutes into a flight then BAM one or two servos go crazy.
I ordered a bunch of Lemons to see if they work better.
So far, I am very pleased with my Lemons.

The Mig is being rebuilt for the 2nd time. Quite simple nose end replacement but my
motivation has been low with other projects already on the bench.

Which leads me to Announce that !!!
I finished my similar sized F-22, to clear that bench,and maidened it last PM.

Using a low cost 3010b motor from HK and a 3 blade prop from a large Quad experiment
and two 2S 1800 paks in series and a mere 2 ea 900 sizes servos.

No pix, no paint or deco just streaking 9mm white foam in post sunset sky's.

I'll get vid and pix up soon.

It practically leaped off the ground. I was expecting a longer run.
My only adjustment will be to add more throws.

I am thinking that this one is going to be my Favorite of the series.
F-22, F-15 and Mig 29 are all large Prop in Slot , 9mm Depron and Slide on Ground capable.

More l8r

Bob
Hoosier Cutout Service
Jun 20, 2014, 08:30 PM
Retired CAD guy
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OK the choice of a 3 blade slow fly Quad prop was NOT a good idea.

I'm using a 10x6 slow on my 50" Sbach with the same motor but only using 3 cells.
the little 3 blade 7x4 was spinning way too fast.

Threw a blade this after noon.
Which managed to NOT tear up the rear fuse.
But did disrupt power for a moment, surprisingly, so now the nose isn't as pretty as it was .\
The motor is a but noisy at the moment so I MAY NEED NEW BEARINGS.

I'll experiment with some other props tomorrow.

it was flying so nicely too. sigh ...

It's worth messing with to get it right .

More later

Bob
Aug 09, 2014, 11:43 AM
Retired CAD guy
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I 've finally gotten around to putting up a video of this monster.

Mig-29 (4 min 39 sec)


Enjoy

Bob
Hoosier Cutout Service

Also check out my F-22 in 9mm video

Yeah yeah is says F-15 but it's NOT it's the F-22

F-15-9mm (2 min 46 sec)
Last edited by birdofplay; Aug 09, 2014 at 02:07 PM.


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