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Aug 29, 2007, 08:11 PM
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Mini-HowTo

Ecee Thunder Rocket Glider R/C Conversion


Greetings all.

I have seen several posts from people interested in R/c rocket gliders... thought I might share mine with you. I was looking for something easy to build, that was a proven design and could be modified for radio control. What I found was the Edmonds Ecee Thunder. My conversion used the kit parts as patterns for pieces made from lighter contest grade balsa. The radio gear is housed in the center fuselage for and aft of the C.G. Two 3.4 gram servos are used to move elevons attached to the trailing edges of the main wing. (Aileron/Elevator mixing is done at the transmitter to provide pitch and roll control.) One 4.3gram servo is used to operate a cam mechanism that locks the canard flap down after motor burn out (instead of the ejection charge operated piston). The canard flap is allowed to float during boost. Flight pack includes a Spektrum AR6100 receiver (3.5 grams) and a 3.7v, 210ma LiPoly battery (3.6 gram). First flight was on an Estes E-9P (launced 30 degrees from vertical). The best results so far have been with the AeroTech E6-RCT RMS (24mm), although it also flys well on the E7-RCT loads. Launch weight, minus the motor, is around 10 oz.
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Aug 29, 2007, 08:22 PM
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I have four flights on it so far (with four scratch free landings) and it flys really well. Boost on an E6 long burn motor is nice and straight but it does have a strong tendancy to weather vane into the wind. Max altitude so far has been around 180 feet (estimated). It is very responsive to pitch and roll inputs and yet still relatively docile to fly. Glide duration is short... about 2-3 minutes. I didn't set out to build an award winning contest duration glider. I just wanted a simple trainer to practice setting up for an approach and landing after a vertical launch. It does that nicely.

This next set of photos show the radio/servo compartment and elevon details.
Aug 29, 2007, 09:29 PM
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2-3 minutes from 180 feet is pretty good. I'd of thought an E-6 would take it much higher than that but it is a draggy airframe. I take it that the canard once locked down remains in that position and is not used for elevator control as thats not needed with elevons so you would still need to properly balance the plane for best glide.

Cool conversion, a friend of mine is [he claims] doing the same thing but we'll see if that comes to fruition. Any video?

Richard
Aug 29, 2007, 09:54 PM
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Thanks Richard
Quote:
Originally Posted by The Tellurian
.... I'd of thought an E-6 would take it much higher than that ...
I thought it would too... since the last flight I have contoured the wing and fin leading edges. Weather permitting I will be able to test that mod this weekend. Will report results.
Quote:
Originally Posted by The Tellurian
.... I take it that the canard once locked down remains in that position and is not used for elevator control..
That is correct. Trimming for a good glide is critical... along with getting the C.G and canard flap deflection right.
Quote:
Originally Posted by The Tellurian
.... Any video?
Yes, but I'm not real happy with the quality. If I get some better shots this weekend I'll post'em.

Regards,

DJ Miller
Last edited by straitup; Aug 29, 2007 at 10:01 PM.
Sep 05, 2007, 05:04 AM
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...well, last weekends tests went well. With the leading edge mods and the refined control linkages, it seems I have myself a real sweet flying little model. However, to get max altitude (450-500 feet -estimated- on an E6-RCT) does require some "technique". You really have to fly this thing strait up during the boost phase, otherwise it will weather vane into the wind something fierce.
Sep 05, 2007, 09:54 AM
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Hey great photos DJ!

Thanks for the closeups of the Thunders linkages. And that launcher is an engineering master piece. Your folks must have given you Mechano sets for Xmas. The picture of the launcher plus Thunder in the van looks like something ready for a James Bond movie.

What is your glide time now with the modified leading edges? What no vids?

Richard
Sep 16, 2007, 07:58 PM
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Thanks Richard!

The linkages are titanium wire bonded/crimped inside telescoping aluminum tubing. Very light, very strong and easy to make. You only get one shot at adjusting them tho... The launcher is a separate story, probably deserving its own thread. Most of the machined parts are straight out of the 8020.net catalog (it's like having an Indusrial Erector Set to play with).

Glide time... hard to say since I haven't been trying for max endurance flights. Every flight so far has been used to check out stability and controllability... which means a series of rapid roll reversals, followed by wind up turns (left and right) and then a stall series. Those manuevers use up a lot of energy/altitude. However, I can say handling is much improved. Penetration in high winds is very good now and control near the stall is very "well mannered ". The stall itself is more of a mush with just a hint of nose bob. There is no noticable break (which is exactly what you want with a canard configuration). Overall I am quite happy with it. Sorry, still no vids... maybe next flight weekend.

Regards

DJ
Last edited by straitup; Sep 19, 2007 at 05:16 AM.
Sep 22, 2007, 12:34 AM
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clipper's Avatar
anyone---
How come the servo in not driving the canard all the time?

nice looking glider, have you tryed slope gliding?

Who supplies the E-6 RCT motor?

thanks
Last edited by clipper; Sep 22, 2007 at 12:43 AM.
Sep 22, 2007, 07:57 PM
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Hi Clipper

"How come the servo in not driving the canard all the time?"

The idea behind this was just a simple conversion. The canard can be used for an elevator but that would probablely add some complexity and basically is unnecessary, the elevons do the job well enough.

The E6 comes from here:http://www.aerotech-rocketry.com/

Richard
Last edited by The Tellurian; Sep 22, 2007 at 08:02 PM.
Oct 10, 2007, 02:27 AM
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clipper's Avatar
DJ

How tall is the launcher and is this the recomended height? What kind of lugs are you using? How about some close up pictures!

Many thanks
Oct 14, 2007, 02:43 PM
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Quote:
Originally Posted by clipper
How tall is the launcher and is this the recomended height?
The launch rail is 96 inches long. You could probably get by with one 72 inches long. The longer length ensures that the model leaves the rail with a velocity of around 35 feet per second. This allows me to launch in winds up to 20 kts.
Quote:
Originally Posted by clipper
What kind of lugs are you using?
I am using series 1000 rail buttons from railbuttons.com. They fit a standard 1 inch rail with a 1/4 inch slot. (To save weight I used nylon screws and nuts through a 1/32 inch ply backing reinforcement.)

Regards,

DJM
Oct 14, 2007, 03:56 PM
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Thread OP
Quote:
Originally Posted by clipper
How come the servo in not driving the canard all the time?
In order to answer that question, I need to address why the canard flap must "float" during boost. It is simply this: The "effective" center of pressure (C.P.) for the canard/wing combination is further behind the C.G. with a floating canard flap than a fixed one. The greater the distance between the C.P. and C.G the higher the static margin and the more stable a rocket you have. When the motor burns out two things happen. The C.G. moves forward and the requirement for a high static margin is gone. In fact, for a good flying R/c glider you want a much, much less "stable" model. Or put another way, you want the C.G. and C.P. to move fairly close to each other. Locking the canard flap down has the effect of moving the C.P. of the wing/canard combination forward (closer to the C.G.) The final element is nose up trim (positive pitching moment). This is the other benefit that comes from locking the canard flap down.

Here is the important part... the lift provided by the canard flap is a function of velocity and deflection angle. This means there is one unique setting that corresponds to the "trim speed" of the model. On the Thunder, that flap angle is about 2/3 of what you would need for good pitch (elevator) response. If the servo were connected to it "full time", you would run out of deflection while maneuvering (and probably stall the canard at the same time... a bad thing). This is why I donít use it as a control surface, but as a trimming surface. (ref: Stick-free static longitudinal stability)
Quote:
Originally Posted by clipper
nice looking glider, have you tryed slope gliding?
Thanks, but all credit goes to Rob Edmonds for the clever design. As for slope flying it... well the terrain in South Texas is really bad for that, so no.
Quote:
Originally Posted by clipper
Who supplies the E-6 RCT motor?
Google search for:Aerotech 24mm RMS-RC hardware... I found mine here.

Regards,

DJ Miller
Last edited by straitup; Feb 01, 2008 at 12:20 AM.
Oct 01, 2008, 04:11 PM
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R/C Thunder Launch Photos and Movies


Finally, some great launch photos courtesy NHRC member Dave Laney

Flicker Gallery

... and movies courtesy NHRC member Jewel Butler.

E7-P motor

E6-P motor

Thanks guys!

DJ
Last edited by straitup; Mar 18, 2009 at 10:17 PM.


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