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Jun 16, 2017, 02:01 PM
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trident58's Avatar
Build Log

RCM Gitano 60- first pattern plane!


Just started building my first semi-classic pattern plane, an RCM Gitano 60. I had purchased the plans a long time ago, back when RCM was still afloat, but never got around to building it. I've just finished getting together all the parts and accessories I need, so I started work on it today.
Power: Cobra 4130 540 kV motor on 6s
Retracts: The World Models electric retracts with 4.5 mm struts
Wing and stab cores from Eureka Airtcraft

Plan link: https://aerofred.com/details.php?image_id=97967
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Jun 16, 2017, 02:41 PM
Raised on 80's Pattern
Fatherof4's Avatar
Great!! Will look forward to watching.

You might want to consider the HV Lipos. I went with Revoletrix 6s 5900 mAh packs on mine and I'm very pleased with the increased capacity and power.

Hopefully you will come and join one of our So Cal Pattern events with it when its done.

Doug
Jun 16, 2017, 08:33 PM
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trident58's Avatar
Spent today getting the wing skins glued together. Trimmed them to shape, and just need to sand them a bit before sheeting the cores.
Speaking of which, this is only the second set of cores I've ever sheeted. On the last set, I used Gorilla glue. Seemed to work really well, but I was wondering if you guys have anything else that you prefer.
Jun 16, 2017, 09:02 PM
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doxilia's Avatar
Z-Poxy Finishing Resin. A slow cure glass layup or laminating epoxy.

I just like to have that added time before the glue starts to kick. Allow to cure overnight before removing from the shucks.

David
Jun 16, 2017, 10:53 PM
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Quote:
Originally Posted by trident58
On the last set, I used Gorilla glue. Seemed to work really well, but I was wondering if you guys have anything else that you prefer.
Either polyurethane glue (such as the GG) or a good laminating resin. I think it is easier to keep the glue weight down with PU as compared to epoxy, but either one will give you a great finished product if you do it right.


Mark
Jun 16, 2017, 11:53 PM
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Gitano 60 Build


Hello. I scratch built one with fixed gear a few years back. I first put a OS Max 61 SF in it and it worked out pretty well. I ,later, put in a Super Tigre 90 which worked out very well. When I built the plane I used contest grade balsa everywhere I could. It helped considerably as the finished plane came in at 6 1/2 pounds, which is pretty light for an 800 square inch wing. If memory serves correct, I think that they used plywood plates supported with dowels to mount the retracts. I think that I would use plywood 1/2 ribs in the foam cores to support the retract mount instead. I covered it with Monokote. It was a very good, true flying, plane. You will like it !! Good luck !! Keep the pictures comming !!
Jun 16, 2017, 11:57 PM
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Gitano 60 Wing


I used the Z poxy laminating resin to sheet the wing. The complete wing, sanded and ready to cover, weighed 16 oz.
Jun 17, 2017, 07:40 AM
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trident58's Avatar
I think I'll give the z-poxy a try, just to be different.
Haven't thought too much about the retract mount, but in looking at the plans, I might just increase the size of the mounting plate, just so it mounts more securely to the core itself. I think adding the dowels should secure it pretty well. BTW, this is also my first plane with retracts, so it'll be a learning experience.
Jun 17, 2017, 09:06 AM
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The dowel method works if your field is pretty smooth and you make decent landings. I have had gear plates mounted with the dowel method loosen after a lot of landings on a reasonably smooth grass field. RC Acro1's suggestion really works well for durability and longevity. I used to sandwich 1/16 ply between two pieces of 1/16 balsa for the support ribs. I would tie them into them leading edge and run a 1/4 square stringer about 1/2 way between the leading edge and the plate that extends 2" on either side of the ribs top and bottom. I can guarantee the plates will hold for at least 600 flights or a catastrophic crash :-(
Good luck and keep posting photos if possible.
Jun 17, 2017, 09:47 AM
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OK, that's interesting about the 1/2 ribs to support the retracts. I fly off a nice, paved runway, and my landings are usually smooth, but maybe I'll look into something like that.
Jun 17, 2017, 10:56 AM
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Had a chance to think this one out. So here's my plan (and please tell me if you think I'm about to do something stupid):
Before sheeting the cores, I'll mark out the location of the retract mount plates. I'll then make two 1/8" vertical cuts through the core, one at the inboard and one at the outboard end of the mounting plate, that extend from the leading edge back to the rear of the mounting plate. I'll then make two 1/8" ply half ribs to place in the slots, extending from the top to the bottom of the cores. That way, when the cores are sheeted, the half ribs will be tied into the top and bottom sheeting and the leading edge, in addition to being bonded to the surrounding foam. I can then epoxy the mounting plates to the half ribs and still use dowels, if needed.
Jun 17, 2017, 12:11 PM
AMA 32832 - SPA L27-VRCS 1138
This is a great treatise on foam wings. Bob Noll's "Perfect Foam Wing Construction" DVD is excellent also.


http://www.mackrc.net/patternwings2/index.htm
Jun 17, 2017, 12:51 PM
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trident58's Avatar
Quote:
Originally Posted by Dave Swanson
This is a great treatise on foam wings. Bob Noll's "Perfect Foam Wing Construction" DVD is excellent also.


http://www.mackrc.net/patternwings2/index.htm
Thanks!
That's very helpful. Lots of good info there.

Jon
Jun 17, 2017, 04:46 PM
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doxilia's Avatar
Jon,

Your half rib approach is sound. However, I would have the ribs "support" the 1/4" plates so the plates overlap the ribs on either side (inboard and outboard). To do this you'll need notches in the ribs the width of the plate so the latter seats into the ribs. To that end, extend the ribs a little further back than the rear of the plates, say, 1/2".

Some people like to "box them in" using lateral lite ply inserts along the length of the plate again on either side or on the underside. A shear web of sorts using lite ply. You can do this by first making your rib slots, sanding tree ribs to foil and then doing your lateral (shear) slots between the ribs for and aft of the plate. When that's done, you can cut the rectangular foam section out to seat the retract plate. For added comfort, rather than use dowels you can drill angled 1/16" holes through the plates and into the shear ply. Then add bamboo toothpicks dipped in epoxy through the plates, foam and shear webs. Four each side and maybe 3-4 at each end and that mount is going nowhere after its all bound together and has cured.

David
Last edited by doxilia; Jun 17, 2017 at 08:09 PM.
Jun 17, 2017, 08:02 PM
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Starting to lay out the retract installation and trying to get an idea where I have to make the cuts in the core for the 1/2 ribs. Going to have to take into account that the retract actuation unit is outboard, so I'll have to make a clearance hole in the outboard rib for it.
Wanted to get this done today, but with the heat wave in SoCal, the interior of my garage is about 105 degrees! Maybe early tomorrow morning.


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