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Old Oct 20, 2007, 06:01 PM
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Hamilton, New Zealand
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Build Log
Super Dragonfly

Hi all,

Just about to get started on my next project the Super Dragonfly that I picked up from Dolphinman through the for sale forum.
The model was sent very quickly and well packaged. Thanks again!

I have spent this evening going through everything and thinking about how I will go about the build. I have never built a model with foam core wings or a fiber glass fuselage so this will be a fun new experience for me.

One update I am concidering is to install a rudder and I would appreciate any feedback from anyone who has done this mod to a Dragonfly, some idea as to the size and shape.

Any advice or tips people have please speek up so that all us beginners can learn something.

Happy building,

Chris
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Old Oct 20, 2007, 06:07 PM
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Orange County, CA
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What kind of wood was supplied for the leading edge of the wings? I would at least use Basswood, or Oak with balsa tip blocks.

PRE-TEST!!!!! the glue for sheeting on the outside of the core beds before sheeting.

DOUBLE CHECK the straightness of your building surface.


The last plane you built was beautiful this one will by just as impressive, I predict.
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Old Oct 20, 2007, 06:13 PM
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Virginia Beach, VA
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Chris

Glad to see you getting to it so soon! I'll will enjoy this thread, and will add my $.02 on occasion, I'm sure. You're gonna love this ship!

Scott
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Old Oct 20, 2007, 06:47 PM
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Hi Chris,

I would definitely recommend the rudder mod to this plane; I don't understand why it wasn't part of the original design. This is a wonderfully aerobatic model and benefits immensely from a rudder. I am able to fly extended knife edge, clean 4 point rolls, snaps, hammerheads, etc. with the addition of the rudder on mine. See the picture; it's self explanatory. Try to keep this plane light as it is quite the aerobat when built as designed. Mine weighs 2 lb, 7.5oz ready to fly.

Doubletap
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Old Oct 21, 2007, 08:04 AM
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Hamilton, New Zealand
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Thanks for the kind words.

Scott had already sheeted the wings with thin plywood and attached the hard wood leading edge and balsa traling edge.

I have started by attaching the hardwood TE to the aileron stock and trimmed to length.

I have noticed that the wing sits up from the building board in the middle, is this normal? Should I just trim the aileron stock to fit?

Take a look at the photos, that should explain it better that I can.
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Old Oct 21, 2007, 08:51 AM
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Virginia Beach, VA
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Quote:
Originally Posted by fooesboy
Thanks for the kind words.

Scott had already sheeted the wings with thin plywood and attached the hard wood leading edge and balsa traling edge.

I have started by attaching the hardwood TE to the aileron stock and trimmed to length.

I have noticed that the wing sits up from the building board in the middle, is this normal? Should I just trim the aileron stock to fit?

Take a look at the photos, that should explain it better that I can.
Chris,

I think that what you are seeing there is a bit of a warp in the wing, and I would say that it is not "normal". Although, I think that kind of warp would not affect flight performance noticeably, unless there is an actual twist in the wing.

I sheeted those wings about a year ago and used my very flat drafting table and the wing saddles to do the sheeting, along with a bunch of books for weight. The wings have been stored in the saddles since then, but not weighted. So, I'm not sure how that occurred, and there is certainly nothing you have done to cause it.

There may be some advice here on the boards on how to straighten the warp. Otherwise, I would be inclined to let the trailing edge stock "match" the slight curvature of the wing as opposed to trimming the stock to fit. In any case, I suggest you fully shape the trailing edge cap first. Not sure what the instructions say, but on the last Super Dragonfly I built, I tack glued the trailing edge stock to each wing in about three or four places with dot of CA and sanded it to shape to match the lines of the airfoil. Then, once the sanding was completed, I carefully cut the trailing edge away with a sharp knife, cut the ailerons to length, beveled them, and glued the fixed portions of the trailing edge stock on each wing.

Is there a twisting warp in this wing at all? How about the other wing? How does that one look?

Scott
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Old Oct 21, 2007, 09:11 AM
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Sheeting Method

One thing I forgot to mention above is that the wings were sheeted using 3M 77 spray contact cement. The leading edge and trailing edge cap were glued in place using 30 minute epoxy. This may be important for those who would want to weigh in on how to straighten the warp.

I have an idea on how to do it, but let's see what the others say first.

Scott
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Old Oct 21, 2007, 11:06 AM
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Hi Scott,

I can not see if the wing is warped or just has some washout. Both wings have this gap, the RHS is almost 5mm at the highest point and the LHS is just over 2mm. I have not sanded the LE flush with the ply yet so the gap is not yet defined.

You are right when you say that the instructions call for the aileron stock to be tack glued to the TE and then sanded to shape it's just that the aileron stock is so stiff that it does not easily bend to follow the "curve" of the wing.

I think that I would like to straighten the wing as I believe that a straight wing is the key to a good flying model so lets hear everyone suggestions!

Thanks!

Chris
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Old Oct 21, 2007, 11:22 AM
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This is why I really prefer epoxy to the 3M77 spray for sheeting.

Here's something you can try:

Heat the wing with a covering iron set on low, keeping it moving all the time, so as not to melt any foam. Warm up both sides. You may alternately try an electric blanket, but it's probably NOT hot enough. an oven, if big enough at 120-140*F might work better...
Once warmed, put the wing immediately back into the beds weighted, but shim the tip and root, and weight the middle of the bed so as to impart a curve to the wing opposite of the curve it currently has. You'll have to work fast before the warmth leaves the glue.
It may be that to get this to work, you have to cut off the LE, STE and tips, to allow the sheeting to travel a bit.
Other than that, vacuum bagging some fiberglass onto the finish sanded wing, before ailerons are cut, and using the same reverse-curving trick, might work.

I'm interested in how you'll get along. Please report your results to us.

G/L,
Target
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Old Oct 21, 2007, 11:25 AM
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Virginia Beach, VA
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Quote:
Originally Posted by fooesboy
Hi Scott,

I can not see if the wing is warped or just has some washout. Both wings have this gap, the RHS is almost 5mm at the highest point and the LHS is just over 2mm. I have not sanded the LE flush with the ply yet so the gap is not yet defined.

You are right when you say that the instructions call for the aileron stock to be tack glued to the TE and then sanded to shape it's just that the aileron stock is so stiff that it does not easily bend to follow the "curve" of the wing.

I think that I would like to straighten the wing as I believe that a straight wing is the key to a good flying model so lets hear everyone suggestions!

Thanks!

Chris
Chris

I agree with your approach. And, certainly you are correct that the straighter the wing, the more true it will fly. So, you have not observed any "twist" in the wings, correct? You got my attention when you used the word "washout", in that washout is a twist that puts the trailing edge of the wing higher at the tip of each wing.

What I am seeing from your photos is that the wing is not twisted, but rather "bent" along its length, with hopefully no "twist".

Sorry about your trouble. Hope we can resolve this adequately for you. In the meantime, you can work on the fuse and/or tail feathers.

Scott
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Old Oct 21, 2007, 11:29 AM
Slope Junkie
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Virginia Beach, VA
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Quote:
Originally Posted by target
This is why I really prefer epoxy to the 3M77 spray for sheeting.

Here's something you can try:

Heat the wing with a covering iron set on low, keeping it moving all the time, so as not to melt any foam. Warm up both sides. You may alternately try an electric blanket, but it's probably NOT hot enough. an oven, if big enough at 120-140*F might work better...
Once warmed, put the wing immediately back into the beds weighted, but shim the tip and root, and weight the middle of the bed so as to impart a curve to the wing opposite of the curve it currently has. You'll have to work fast before the warmth leaves the glue.
It may be that to get this to work, you have to cut off the LE, STE and tips, to allow the sheeting to travel a bit.
Other than that, vacuum bagging some fiberglass onto the finish sanded wing, before ailerons are cut, and using the same reverse-curving trick, might work.

I'm interested in how you'll get along. Please report your results to us.

G/L,
Target
Target,

I was thinking along the same lines in regards to correcting the "bend". Perhaps warming the wing in the sun or by some other means of getting a uniform heating would also work.

Scott
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Old Oct 21, 2007, 12:00 PM
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I would do what Target suggests. Use some heat and reverse bending. That may just do the trick.

Doubletap
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Old Oct 21, 2007, 12:35 PM
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Harbor City, CA
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Quote:
Originally Posted by Dolphinman
Target,

I was thinking along the same lines in regards to correcting the "bend". Perhaps warming the wing in the sun or by some other means of getting a uniform heating would also work.

Scott

Maybe a hi-temp electric blanket? You'll need to get the glue hot enough to let go a bit...If just putting it in the sun worked, I would think that the glue wouldn't be very good for our use anyway. the sheeting would de-lam on one good day in the California heat on a summer day!

T
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Old Oct 21, 2007, 12:41 PM
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You can try heating it up by CAREFULLY waving it over your barbecue/outdoor grill.

Doubletap
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Old Oct 21, 2007, 12:47 PM
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Orange County, CA
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STEAM


I would consider heating each pannel up in a steam box/bag. That is how I have seem foam bent in a shop before. Ii is also how woodworkers make curved wood pieces, like rails on a rocking chair.

HIGH HUMIDITY HEAT is what I would try. That wat the wood parts of the wing will soften in the moist heat and hold shape once dry and cool.

STEAM BABY

Dave
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