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Old Aug 19, 2006, 10:38 AM
Off 2 The Edge of Reality
TeamTEOR's Avatar
Scottsdale, AZ
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Chuck, what gearing are you using in that 12mm Feigao?
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Old Aug 19, 2006, 12:41 PM
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Syracuse, NY (USA)
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I'm finally starting to build my first PTM. I'm using Gorilla glue (first time ever) to keep it as light as possible. I'm using the Pico Moth directions pdf file someone posted on here - thanks!
The fuselage weighs 27grams (two halfs glued together, the stick, and the stock tail dragger).

Is the IPS a "friction fit" or do I glue the stick in? I think it's a friction fit - good thing I stopped sanding the stick before the stick got too small!

Replacing the stick when it breaks will be tough. I tried to resist using much glue on it.

The thrust line was not clear at first. I now realize it's just a visual aid to make sure the stick is sitting flat against the foam. The thrust angle is in the foam and angled such that the thrust line drawn on the stick should be barely visable and parallel to the foam. Doesn't seem necessary to draw the line to me.

Haven't decided if I'll cut plywood to glue onto the struts, or if I'll use any "wires".
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Last edited by Block; Aug 19, 2006 at 07:26 PM.
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Old Aug 19, 2006, 08:55 PM
Captain Carnage says......
AirWarriorBelgy's Avatar
Seminole (St Pete.), Florida/ Seminole Crash Fest
Joined Jun 2002
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Quote:
Originally Posted by TeamTEOR
Chuck, what gearing are you using in that 12mm Feigao?
"A"

but..it's the Feigo 25l for ducted fans.. gonna try an 8x6 in the morning.
The 7x6 SF was 3.3 amps static. I wanted to keep it to about 2 amps at the onset of this BL experiment, have the 8x6 installed now *went to LHS this morning* will check current draw at the flying field before flight.

Only using two cells on this set up anyway so as long as I don't exceed 5.5 amps I won't be pushing any of the system components to limit.

Chuck
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Old Aug 19, 2006, 09:01 PM
Captain Carnage says......
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Seminole (St Pete.), Florida/ Seminole Crash Fest
Joined Jun 2002
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Quote:
Originally Posted by Block
I'm finally starting to build my first PTM. I'm using Gorilla glue (first time ever) to keep it as light as possible. I'm using the Pico Moth directions pdf file someone posted on here - thanks!
The fuselage weighs 27grams (two halfs glued together, the stick, and the stock tail dragger).

Is the IPS a "friction fit" or do I glue the stick in? I think it's a friction fit - good thing I stopped sanding the stick before the stick got too small!

Replacing the stick when it breaks will be tough. I tried to resist using much glue on it.

The thrust line was not clear at first. I now realize it's just a visual aid to make sure the stick is sitting flat against the foam. The thrust angle is in the foam and angled such that the thrust line drawn on the stick should be barely visable and parallel to the foam. Doesn't seem necessary to draw the line to me.

Haven't decided if I'll cut plywood to glue onto the struts, or if I'll use any "wires".


Hi Block

welcome to the TM Sqaudron

as for Ply on the struts...skip it add .012 CF rods to the leading and trailing edges (look at the Blue max pics on prior page...you can easily see the rods). regular thin CA does this up nice and right.(keep your fingers out of it though )

as for the stick ...put a small servo screw in the side of the Gearbox into the stick...sooner or later everyone that has done "friction only" has had the motor slide off the stick in flight....sometimes the results are not too pretty.

as for flying wires...do em if ya feel the need....2 yrs on ol blue and no wires
just don't try drastic manuevers in higher winds...and stay away from negative "G" dives...and you should be okay.


Chuck
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Old Aug 19, 2006, 10:22 PM
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Syracuse, NY (USA)
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Thanks...someone simply glued balsa or basswood only to the vertical wing braces - that is tempting. It would also give me more surface area to glue to the wings. I'm surprised nobody has replaced the struts with a sheet of balsa with a circle cut out of the middle to save weight...it would work well, but not look too great I suppose.

I'm waiting for the Gorilla glue to dry on the lower wing (the single fold wing with the PVC on the gap). Tricky getting the PVC to stay flat aginst the wing - ended up using blue masking tape around the edges of the PVC.

I decided to not use Epoxy in the gap. Not so sure about the upper wing though since there is nothing to hide the ugly Gorilla glue. I have some ~4" wide black wing tape that I could use, but eveything adds weight....
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Old Aug 19, 2006, 10:37 PM
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Jacksonville, FL
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If you sit and stare at the gorilla glue while it sets (yes, I am seriously suggesting you sit and watch glue dry ), you can shape it into nice fillets as it expands. Even just checking it every 15 minutes or so will suffice. You can also accellerate the process by mixing a little bit of water into the glue before use.

Doug
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Old Aug 19, 2006, 11:03 PM
Off 2 The Edge of Reality
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Scottsdale, AZ
Joined Sep 2003
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Quote:
Originally Posted by AirWarriorBelgy
"A"

but..it's the Feigo 25l for ducted fans.. gonna try an 8x6 in the morning.
The 7x6 SF was 3.3 amps static. I wanted to keep it to about 2 amps at the onset of this BL experiment, have the 8x6 installed now *went to LHS this morning* will check current draw at the flying field before flight.

Only using two cells on this set up anyway so as long as I don't exceed 5.5 amps I won't be pushing any of the system components to limit.

Chuck
Chuck, bring out a temp gun with you as well. In personal experience with the 36L motor after 3.8amps it really started to get HOT and QUICK. A buddy of mine used one of the AON 12mm motors with very little luck (surprised the heck out of me too) the first motor siezed and the second also got hot quick, but he had be overproping a pinch. None the less it was the same wind as the 36L, and at 4.1 amps it didn't take too long till something happened. These motors work great, but are fragile. I hope it all goes well budddy. My TM will be out at the field tomorrow.
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Old Aug 19, 2006, 11:22 PM
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Yep, I'm going to the cellar every 15 minutes to push down the PVC and get a (very little) extra/expanded glue out. I put quite a few drops of water in the fold and then mixed in some glue - it foamed w/in minutes. I used a wet paper towel to smear more glue around on the wing and the PVC. But I think I should have used even more water so it would cure quicker. I'm going to wait and see if the dihedral holds nice (stiff) before I use Gorilla on the other wing instead of epoxy. Or is the wing flexing normal? My slow stick wing is very stiff (it has the rods and epoxy), so this wing seems odd (weak) to me.

The directions say at least 10% moisture is needed, 10-25% is ideal. I doubt foam has any moisture in it, so "lots" of water is probaly needed.
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Old Aug 19, 2006, 11:59 PM
Off 2 The Edge of Reality
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Did you laminate the plastic struts with carbon or balsa/ply? If yot that is why you would be seeing any flexing. This is a pico plane, it will flex, but once you put it all together it should be pretty solid for the most part.
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Old Aug 20, 2006, 07:57 AM
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No struts yet - I'm at the point of glueing the "fold" to set the dehedral in the wings. I like the way the slow stick goes together - those rods along the leading edges add a lot of strength and save the wing from dings. They are ugly though.

Quote:
Originally Posted by TeamTEOR
Did you laminate the plastic struts with carbon or balsa/ply? If yot that is why you would be seeing any flexing. This is a pico plane, it will flex, but once you put it all together it should be pretty solid for the most part.
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Old Aug 20, 2006, 09:25 AM
Off 2 The Edge of Reality
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Scottsdale, AZ
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Thats a Slow Stick tho, looks a little odd, but floats like a dream. Wait till you get it all together, it will feel good and solid. I almost always tend to overbuild planes, but this is one that doesn't need the rods on the wings. Laminating the struts will solve your problem. Try out the wing wires as well with some light string.
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Old Aug 20, 2006, 10:04 AM
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My lower wing came out pretty good - it is stiff enough.

But the wing does not fit well under the fuselage. The arched/recessed portion of the fuselage that the wing sits against is not quite long enough - is that normal? I think need to sand away 1/8" of the fuselage (or the LE or TE of the wing).

For the horizontal stabilizer, I sanded the joint (same as done on the slow stick) - it came out really good. Does the GWS hinge tape stick/hold OK, or should I use packing tape?
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Old Aug 20, 2006, 03:13 PM
Off 2 The Edge of Reality
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Scottsdale, AZ
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Block, it happens. I had to sand a little as well.

The GWS tape does not last to long, grab a roll of packing tape, but Blenderm works better. DuBro sells it as hinge tape.
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Old Aug 20, 2006, 04:51 PM
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Daytona Beach, Florida, United States
Joined Aug 2002
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Hey, Teor.. what's up in your world? I just thought I'd throw in another suggestion for hinges that Block might be able to use. I've taken old 5.25" floppy disks, pulled off the jacket, and cut hinges out of the material the disk is made of. Just notch each side of the control surface on the end, put a drop of foam safe CA in the notch and slide the small piece of disk material into the notch you made. Do that on both ends of, say the elevators, then notch the fixed rudder and stab ends in the same place and slide them in there also. I have used 2 hinges per side for the horizontal stab and two on rudders. They never wear out. Just my 2 cents worth.

Buzz
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Old Aug 20, 2006, 07:02 PM
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Jacksonville, FL
Joined Jun 2006
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On the poly glue - there's only so much water you can mix in to the glue before it becomes saturated. At that point, additional water either beads on the surface or sits inside the blob of glue as an "air bubble" of water. I don't mix in the water unless I'm in a hurry ... but then again, I live in Florida and it's August - sufficient humidity is definitely NOT a problem.

On the wing cutout - of the two moths I've built so far, and the third I'm helping a friend build, all 3 needed the rear of the wing cut-out in the fuselage enlarged. On my second moth, I also had to sand the profile of the wing cut-out a bit for a nice match to the wing surface. No biggee - just remember to take a wee tiny bit off, check the fit, then take some more off ... you can always take more off, but it's rather harder to put it back. :-)

On the tail hinges, for my second moth, I used the approach Buzz mentioned except that I used overhead projector transparency film instead of old floppies (which I now regret throwing away ). It works great, and I doubt I'll ever use anything else. To make it even easier, I took some sheets of the printer transparency material, and printed a 1/4" grid on them - this makes it easy to cut hinges the same size every time. Be very careful, by the way, cutting the slits for the hinge material - that foam is thin, and you want the slit to be straight down the middle (parallel to the top and bottom surfaces).

Doug
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