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Old Nov 06, 2009, 12:21 PM
treefinder
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Build Log
60" span motor glider - OSG!

Starting a separate build thread for my entry in Outcastzeroone's contest thread http://www.rcgroups.com/forums/showt...1112240&page=8

I saw the contest idea while on a driving trip to texas, and having lots of time behind the wheel staring at interstates, started figuring out the plans.

In brief the contest is to make a plane from one sheet of Dollar store foamcore Handiboard (20"x30") for some intended purpose like speed, heavy lift, duration, etc. Pondering the duration idea, I wondered how long a span glider could be made from the handiboard. From that came the design for the motor glider.

Specifications:
Span: 60"
OAL: 28"
AUW 6.36oz without battery
Motor: ELE C20 2100kv with GWS 6030dd prop
Servos: 4.3gm (version 1 used Hextronix 5gm servos)
Battery: Have tried 2s 900mah Mystery, 2s 460mah Rhino and 3s 500mah Common Sense packs.

Glider video 1 (1 min 40 sec)


addition 8/12/10 This link is for a page with two pictures showing patterns for the credit card control horns and control rods with z-bends on ends and v-bend for micro adjustments: http://www.rcgroups.com/forums/showp...postcount=8810

3/16/2011 update: I've posted a picture of V3 with KFM2 wing, which is what I recommend as the best flyer and an easy build, and a text file that has the gear that will fly the glider nicely (not a rocket, but will climb to altitude easily in gentle winds). If ordering from HobbyKing, it comes to under 100 grams, so qualifies for their least expensive shipping.
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Last edited by springer; Mar 06, 2012 at 09:58 AM. Reason: video added
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Old Nov 06, 2009, 12:26 PM
treefinder
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Here's the foam layout for pieces on a 20x30 inch sheet. I found it easy to just draw lines on the foam lightly and cut from there, rather than cutting out templates. All lines are straight, and there is no scrap between pieces with the exception of the few small blocks that are colored white in the picture. I ended up using all of them as well for minor fillers, etc.

EDIT 3/25/10: here's an updated dimension pic (jpg) that shows the most recent thinking. it includes the full 30" span center section, with tow 15" tips, the 90deg to top fuse surface firewall. Steps are still 40%, but a couple of guys have built like that, Or you could slide the step back if you want to do a top step at 50% and sand the LE to eliminate the step on LE. Scrap triangles are useful for the wing stops, and minor fill in's like at front of wing seat, where there may be a small gap.
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Old Nov 06, 2009, 12:35 PM
treefinder
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After cutting out all the parts, the first glue up is the monobloc. It includes two large pieces with 3 smaller ones inbetween. I laminated them with Gorilla glue, which is used on most of the rest of the plane as well.

While it's curing, make two cardboard pieces like the smaller foam pieces as fillers to build thickness to the 1" fuse bottom width.

Glue the sides to the monobloc.
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Old Nov 06, 2009, 12:40 PM
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Next while the front of fuse is still held in place, glue the tail tips together. this makes inserting the triangle shaped aft fuse top and bottom easier. I glued the bottom triangle in first, but suggest that one glue the top one in first to make the horizontal stabilizer glueup easier.

Laying the fuse on it's side, you can glue in the fuse forward top piece.
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Old Nov 06, 2009, 12:46 PM
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The horizontal stablizer is two halves, that must be edge glued together before installing on the fuselage. I also used tape to attach the elevator to Stabilizer before glueing the assembly to the fuselage
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Old Nov 06, 2009, 12:58 PM
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Here's more pictures showing the tail empennage setups and the motor mount. The firewall is just a 1x1" piece of 1/8th ply.

Special note here: I am still working out the thrust angle to achieve a good half throttle climb without the nose popping up. The plans call for the firewall to be 90degrees to the fuse bottom. I'm finding that it may be more appropriate to make firewall 90 degrees to the top surface of fuse to start. More to come on this...
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Old Nov 06, 2009, 01:32 PM
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Wing construction: I found the handifoam without paper skins to be really easy to roll into a gentle UC airfoil over the edge of my work table. Doesn't need much. I roll the main wing to about the middle of the chord, and the bottom step across it's complete chord. The glue up of these parts is something I've done differently each time I do it. Best so far is to use masking tape to tape the leading edges together, apply Gorilla glue to one surface (the step) and moisten the other (main wing part) then put a weight over the aft edge of step, and a spacer (i used a Tsquare about 1/4" thick) under the leading edge to maintain the foil curve. Once they are glued, I carved/sanded the leading edge into a more airfoil-like shape, and sanded a groove in the lower surface LE to accept the skewer/dowel. I steam bent the dowel to the dihedral I wanted (1.5" per side to the start of wing taper) Then applied packing tape to the bottom surface, wetted the dowel, applied glue to the groove, pressed the dowel into the groove, and wrapped the tape around the LE. This is tricky and tedious, as you might expect. You can do one side at at time, but have to insure the center joint lines up and is tight as well. Tape on the bottom of center joint will help hold it together, and Glue in the top with tape over keeps th foaming glue contained.

Whew! long explanation!
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Old Nov 06, 2009, 01:37 PM
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A few more details:

The wing saddle is made from the long triangle piece cut from the tapered portion of wings. I made a template from the wing bottom surface and fitted it to the piece, then cut and glued it to the fuse sides so the wing sits right on the fuse top surface.
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Old Nov 06, 2009, 01:44 PM
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Final construction detail: Here's the battery/servo compartment picture showing how I set them up. Note that the elevator V bend is in this compartment for final length/trim adjustments, while the rudder is on outside.
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Old Nov 06, 2009, 06:10 PM
RC = FUN
Fort Wayne, Indiana
Joined Aug 2008
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That's hilarious! I was thinking of a glider I could build today out of my Cheap foam board and then searched and you just put this up today! Awesome Springer! Will build one soon! And what prop are you using? -Tyler
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Old Nov 06, 2009, 06:27 PM
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Fly: Glad it works for you! serendipitous, eh? Well, I hope you enjoy it. It's given me a new respect for the air we fly in.

I've tried a gws 6030dd, flys her ok, but is fragile for a plane without any landing gear; a Haoye (sp?) 7x5sf prop from Hobby King (currently on V2) and a 6x3 graupner folding prop currently on V1. The folder is probably the best to use generally as it seems to help in the glide (as one might expect)

I just recut the nose angle to be 90 degrees to the fuse top surface rather than bottom for more down thrust. I noted in the picture of motor mount that it might be necessary. Flew it a couple of packs this morning and she still (with two washers in top hole) wants to go nose up at anything over 1/4 throttle, but glides nice and level w/power off, so I'm pretty sure it's thrust angle. I think we're getting some relatively calm air Sunday morning, so will try then if not before and report results. Let me know how yours goes!
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Old Nov 06, 2009, 07:19 PM
RC = FUN
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It could also be the wing angle. Try adding a popsicle stick on the back of the wing and see if htis helps. It will decrease the angle a bit. That's what I had to do for my Supercub. -Tyler
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Old Nov 06, 2009, 07:53 PM
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Could be. Right now I have zero degrees incidence to Stab (both wing and stab on top of fuse. The foam's already cut, so I'll try the new downthrust out and then tinker with the wing incidence. The fact it glides power off so nice keeps me coming back to thrust angle, but I'm sure the incidence can be tuned as well.
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Old Nov 06, 2009, 09:21 PM
RC = FUN
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alright, well keep me updated. I don't get one thing though... How did you make the slight curve in the wing? I forget where the call it where the wing is like this: (

Maybe cambered? Or not, I'm not sure. But how did you add this in? -Tyler
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Old Nov 07, 2009, 10:18 AM
treefinder
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Yup, the curve is called Camber and the wing is under cambered hence UC wing. I just rolled the curve in over the edge of my work table. Here's a video by one of the Masters, Tony65x55, showing how he does it for the BluBabys that lots of us have made: http://www.rcgroups.com/forums/showt...ight=tony65x55
I found that the Handiboard foam without the paper skins really curves easy, and doesn't crease too bad (in other words it will curl but not break at the line of the table edge. What you want to do is compress the foam a bit on the inside of the curve.)
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