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May 02, 2010, 01:42 AM
Gasbags & Gussets
jswain's Avatar

Wing spar ......

The wing spar that came with the kit didn't inspire confidence with me. I plan on replacing it with carbon fiber or insert a birch wooden dowel inside the kit supplied one. I put a wood dowel in my multiplex EZPro fiberglass wing joiner/spar and can launch it in a normal manner (not pedal-to-the-metal)on the club sailplane winch without worry so it a valid solution for this model i believe.

Thanks for the build log too, its interesting.

john s.

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May 02, 2010, 03:43 AM
aka MadMan
rjmanzuk's Avatar

RLG candidate

Anyone have any experience with these. Looks to me to be a good possibility.

RC Plane Jet Scale Electric Retractable Landing Gear Retract (0 min 34 sec)

sonicrcmodel — December 10, 2007 — Exciting new electrical retracts that weigh only 6.5 ounces for the total setup. Each strut has almost an inch of downward spring loaded travel for maximum shock absorption. Installation is as simple as mounting into your model and connecting the 3 retract units servo wire plugs into the master retract controller then plugging controller into your receivers gear channel. No air tanks, air lines, or complicated setups. Does require one servo for the nose steering. Struts are removable from retract unit allowing you to customize for your particular application.
Last edited by rjmanzuk; May 02, 2010 at 03:46 AM. Reason: added text
May 02, 2010, 01:41 PM
Sir Crash Alot

Sonic RC Models RLG

They look nice. I veiwed the video at their site and am impressed with their action. A table test with the gear operating without any support showed that they are well balanced and do not appear to be subject to any type of the movement shock that mechanical or pneumatic retracts are.

And the price is reasonable. I would just be concerned about their weight capacity. The website shows 6 lbs for the base model (not sure which ones you were looking at) and this model is going to be pushing that. I haven't even got the electronics in mine and it feels heavy.

They have some for about $120 that have a capacity of 7.5 lbs that I would be more comfortable with.

Let us know which ones you chose and how the install goes. I'd like to see it.
May 02, 2010, 02:33 PM
Sir Crash Alot
Originally Posted by jswain
The wing spar that came with the kit didn't inspire confidence with me. I plan on replacing it with carbon fiber or insert a birch wooden dowel inside the kit supplied one.
Please correct me if I am wrong. Make sure you are looking at the right component. It sounds like you may be mistaking the fiberglass elevator pushrod for the wing spar. There should be a round steel bar that acts as the wing spar.

In either event I too had considered replacing the wing spar with a carbon fiber rod too save a a little weight over the steel rod.

I can't do anything about it now without tearing open the wing and it may be a bit of overkill, but I would prefer to have a full length spar rod. It would be rediculous in length, but I would have warmer, fuzzier feelings about it.
May 02, 2010, 04:10 PM
Gasbags & Gussets
jswain's Avatar

Your correct, my bad

Originally Posted by NewEMan
Please correct me if I am wrong. Make sure you are looking at the right component. It sounds like you may be mistaking the fiberglass elevator pushrod for the wing spar. There should be a round steel bar that acts as the wing spar.
Your correct, i got these components backwards.

If you have not already seen, there are three construction videos, build, motor upgrade, and remote video camera on you-tube.

98" 4-Ch Brushless RC UAV/Drone Aircraft * Build & Maiden Flight * (13 min 33 sec)

May 02, 2010, 05:41 PM
Sir Crash Alot
Originally Posted by jswain
...i got these components backwards.
Glad you got it worked out. It happens. The guy in the build video had a similar problem that he attributed to a lack of instructions, using the fiberglass pushrod as a guide tube for a pushrod to the elevators.

I've watched all three videos numerous times. Mostly while waiting for my kit to ship/arrive.

The videos are a great resource like this forum, giving people a chance to see how others did it and take the advice or think of alternatives.
May 02, 2010, 05:47 PM
Sir Crash Alot

Front Landing Gear Construction Problem

Hoping for a bit of advice on this one. The manufacturer must have come up with a new formula for plastic that is impervious to all adhesives known to man and some not.

I have tried expoxy, CA and a plastics glue that claims to "bond to almost anything" and each time after adequate curing time I go to work on the strut cover, sanding/preping for paint and the two halves pop apart and whatever adhesive I had used practically falls right off.

I wonder how the MQ-9 would perform as a taildragger...

Any suggestions?
May 02, 2010, 07:31 PM
What goes up...
Krylon's Avatar
Duct Tape!

Failing that i don't know, got a pic of the offending part?
May 02, 2010, 09:24 PM
Sir Crash Alot
Originally Posted by Krylon
Duct Tape!
You think your kidding. I'm just about there. Now I just have to decide between black and aluminum.

Black is scale and aluminum is shiny...

I have never had this much of a problem adhesing something.

Between various adhesive trys I have completely cleaned out the old and scuffed the surface. In the pick you can see the remains of some Medium CA.
May 02, 2010, 09:36 PM
Sir Crash Alot

Horizontal Stab Install Mod

I previously reported that when I installed the horizontal stab spar I only inserted about 2" leaving about an 1 3/32" out so I can make the stabs removable.

I didn't like the idea of scrapping off or scratching up a whole bunch of area where the stabs mount, plus these things are almost as big as some wings so it may prove to be helpful.

Anyways. See the attached picture for my idea and give me any thoughts you may have.

While I have not finished the mod yet because I am lacking some washers and cotter pins, I think you will get the general idea.

You can see where the spar exits the tube there is about a 1/4" exposed. My thought was to put a well fitted washer over the exposed portion (black line), seating it firmly against the tube (I may add a layer of material to the tube to give it a bit more girth) and drill a small hole through the spar through which I will put a pin (yellow line) that rests snuggly against the washer.

Given the calculations I have done I think the top speed for this will be somewhere in the ares of the upper 60mphs with a stall speed of about 28mph and a comfortable cruising speed in the low 50mphs; so I do not believe the stabs will experience such a significant amount of drag that this alternative mounting method will cause grave danger.

Anybody disagree?
May 02, 2010, 09:48 PM
Sir Crash Alot

Possible Motor/Prop/Battery Combo

After given some long thought to the models characteristics and estimated performance specs I think I may go with the following (or similar):

Turnigy 4258-800: (Currently out of stock)

With an 11x7/11x8 3 blade prop and 4S 3000mAh 15C battery.

I'll probably go with a straight-up ESC, w/no BEC, and mount a receiver battery up front.


I attached a zip file with the specs for many of the Turnigy motors.
May 02, 2010, 10:12 PM
aka MadMan
rjmanzuk's Avatar

Another possible power system

Because I already have one still in the factory wrappers, I think I will start with:

Great Plains Electrify RIMFIRE 35-48-850kV

and buy a Great Planes Silver Series SS-60 (60A) HV brushless ESC

and start with an APC 3-bladed 11x7 and 3-bladed 11x8 (both of which I already have)

my starting battery will be a 3S 3300 mAh LiPo (of which I have several).

I'll go with a BEC if and only if I decide to run with the retractable LG.

That's my going-in picks for now, and the MotorCalc report looks pretty good for that mix, as long as I don't try to do much 3D stuff.
May 02, 2010, 10:16 PM
Sir Crash Alot
Originally Posted by rjmanzuk do much 3D stuff.
Do it! And send us pics of the clipped wing version after.

Great Planes, Great Planes...If I had the stuff lying around I too would probably use it, but over the past year or so I have started to fall out of love with Tower Hobbies, ergo "my" choice.
May 03, 2010, 05:11 AM
Confirmed UAV'aholic
Skynet-UAV-'s Avatar
In regard to wing spars, anything more than a third of the wing span is just adding weight.
May 03, 2010, 09:39 AM
What goes up...
Krylon's Avatar
If you're still having trouble gluing that plastic you could try NoNails, since all the non solvent adesives have been rigid glues, maybe it needs something with a tiny ammount of flex to stop the joint cracking.

This is the stuff, i expect you can get this or something similar where you are.

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