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REV 2.4 - Wed Aug 10 18:49:03 2011

Geminee Thunder
13326 Preuit Place
Herndon, VA 20170-4341
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SPECS: 23.25" x 23.25" - oz
ROCKSIM FILE: MISSING - please submit here
SpaceCAD FILE: MISSING - please submit here

(Contributed - by Frank G. Whitby - 05/17/05)

Geminee Thunder is an upscale version of the Edmonds Geminee twin glider.

Edmonds Gemini Thunder

As with other Edmonds gliders, the kit comes complete with detailed instructions and well designed, precision cut balsa parts ready to be assembled. All of the parts were in perfect condition and high quality balsa was used throughout.

The assembly was very simple. Rob Edmonds justifiably prides himself on producing kits comprising the minimum number of parts and requiring no re-fitting of pieces prior to assembly. All pieces were dry fit and then glued with very small amounts of 5-minute epoxy. The instructions suggested using wood glue, but I did not have any on hand. I used epoxy sparingly so as to prevent unnecessary addition of weight.

The motor mount and coupler that joins the two halves of the glider required some careful adjustment during assembly. Alignment of the fin tips was aided by laying out the pieces on wax paper for gluing. The instructions recommend balancing the gliders with clay, but I could not lay my hands on any. I used some lead shot and masking tape to weight the nose of each glider instead. I did not measure the final constructed weight of the gliders.

The construction can be accomplished in an hour or so, but I spread out the construction over a few days. Construction is well within the ability of novice builders and the gliders have a very nice, stout feel to them. The biggest problem I faced was transporting the gliders to the launch site without inadvertently sitting on them in the car or other rough handling.

I did not paint the glider.

Construction Rating: 5 out of 5

Edmonds Gemini Thunder

The instructions suggest using a D12-3, so that is what I used. I made a small thrust ring of masking tape and then taped the motor securely in place. The glider boosted very nicely to 200 feet or so and separation was very near apogee or just a bit past. The two gliders fell away from each other, began to descend, turned gently away from each other and came back up wind in a beautifully symmetric pair of spirals. The two gliders nearly met at the middle of their long sloping turns and then touched down at almost exactly the same moment about 100 feet apart traveling in opposite directions. The rear glider snagged a 12 inch tall clump of weeds at the last moment, causing it to twist as it hit the ground and caused the nose piece to break off. The front glider landed gently with no damage.

The motor mount tube was badly scorched by the heat of the D motor. The tube is crusty and slightly misshapen. I think I will have to replace it before the next flight. The nose of the rear glider can be glued back on and should be just fine. I think the noses of both gliders have slightly too much weight in them, so I could probably achieve a slightly shallower and more stable glide path if I removed a gram or so of nose weight from each glider.

Flight Rating: 4 ½ out of 5

Construction and flight of all Edmonds kits that I have built to date have been very satisfying. The Geminee Thunder is simple to build and would be an excellent choice for a beginner modeler wanting to show off with a beefy glider. It looks to me like the gliders should be able to withstand boost on an E impulse motor, so I plan to try this next. Despite the damage to the motor mount from the engine, the design appears to be flawless.

Overall Rating: 5 out of 5

(Contributed - by Hank Helmen [Who's Who Page] - 01/29/06) Edmonds Geminee Thunder

The Edmonds Geminee Thunder is a twin glider with a single 24mm rear engine. The gliders are supposed to boost up on D12-3 and then separate using the ejection charge. Glider should then circle slowly back to earth!

Included in the kit is one balsa nose cone, one balsa "plug" (to join the glider body tubes), two 25mm body tubes, four sheets of 1/4" laser cut balsa parts, a chunk of clay, and a 3/16" launch lug. The balsa is very light weight (soft).

Geminee's instructions consist of two 8-1/2" X 11 notebook sized pages black and white printed on both sides with good diagrams. I found the gliders easy to build, but I have built many R/C airplanes and rockets before.

Edmonds Geminee Thunder Instructions are OK but more information would really help this kit. The engine mounting details and the glider testing department are lacking. There was no instruction as to how to prepare the engine mount other than "use masking tape to tape the engine in tightly". Also the instructions did not tell that the engine stays in the second glider during the recovery glide, and therefore should be test flown with a spent engine casing in place.

The instructions that are there are easy to follow. The fit of laser cut parts is good. The only special tool that you need is a true flat surface large enough to accommodate the 23 1/2 inch wing span of this beast! I used a vertical milling table and weighted the 1/4" balsa down to keep it perfectly flat.

There is no guidance in the instructions as to how to paint or finish the model. I assume this is because if you want maximum glide performance, you need light weight. Testors spray paint or most any other typical paint will add a whole lot of weight to these big wings and change the center of gravity drastically.

Edmonds Geminee Thunder Competitive rocketeers know that painting boost gliders hinders performance so they don't do it! I chose to give the Geminee two coats of Aerogloss clear dope thinned 50% in order to give it more strength and help protect it from wet grass, etc. I also used bright permanent markers to aid in tracking and recovery. There are no decals in the kit. Titebond yellow carpenters glue was used for wing and fin joining.

Construction Rating: 3 ½ out of 5

The only recommended motor is the D12-3. Preparation is easy, just stick the engine in and insert your igniter. No wadding is required.

On my first and only launch the gliders began straight on lift off but after about 40 feet up began to arch over toward St. Louis! Under full engine power the Geminee nosed straight down into terra firma! The engine then ejected with a very sharp and loud "boom!" The engine casing may have flown higher than the gliders! I used a 24mm C11-3 for the first flight. I'm not sure if this affected the flight. Perhaps the D12 would have accelerated faster and given a straight boost? I dunno. Once again there are no troubleshooting flight tips in the instructions such as what type of launch rod to use or what size engine not to use, etc.

There is no shock chord on this model. All of the balsa is very lightweight 1/4" stock.

Luckily the ground was soft from recent rain and the only damage was that the nose cone was pushed in flush with the front body tube along with a lot of mud.

Edmonds Geminee Thunder I'm thinking that I should have used a larger diameter and perhaps longer launch rod. I used only a 36" long 1/8" diameter rod. I think this thing needs to get some speed up for dynamic stability before letting it go free.

For some reason I took the upper glider and gave it a "test glide" after pulling it out of the dirt. The forward part of the fuselage snapped in two where it joins the body tube on landing again, right along the grain. This was the second or third time this had happened. Repair was easy and I plan to fly this thing again as soon as we get a calm day and I have the time.

Flight Rating: 2 out of 5

This is a pretty good kit but it needs some improvement in the instructions department. The main PRO of the Geminee Thunder is of course its size and excitement of twin gliders floating down.

The CONs are that the instructions should give more information on test gliding in tall grass to verify center of gravity of each glider. They also need more information on how the engine should be mounted and how the glider uses the ejection charge to separate therefore the engine must remain in place during the entire flight. The fuselage balsa should to be stronger, I have used 1/2" Carbon Fiber Laminate "tape" from Hobby Lobby International to reinforce my fuselage sides where they join the glider body tubes.

Overall Rating: 3 out of 5

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03/06 - "Follow up to above review: Repaired Geminee Thunder glider fuselage and nose cone. Re-balanced both glider with hand toss test flights. March 11, perfect clear, no wind day. Made a new launch gantry consisting of 3/16" steel launch rod 4.5 feet long. Two 24 inch crossed two by fours for a base and a two foot extention post to hold the gliders up off the ground. Geminee Thunder on D12-3 launched well but began to arch over at 75 feet altitude. Looked like a classic nose dive into the ground but the gliders pulled out of the power dive at 30 feet and flew horizontally at Mach 2 for 50+ yards when it began yet another strange turn then... Exploded Spectacularly from the ejection charge! Balsa rain! Trailing edges of both glider's wings were badly burned from the engine exhaust. Had to extinguish wings with water bottle. Nose cone is Gone and balsa joiner piece is black and shredded. Probablly the most exciting rocket launch I have ever witnessed~! Repairable? Have to wait and see, Geminee is currently in a deep coma, on operating table (workbench) ... Hmmmmmm Hmmmmmm ... tick tick tick. What if it comes back to life and then goes back to its same bad habits?" (H.W.H)

01/06 - "Interesting review. Accurate in that my forward glider's glider to body tube balsa broke every time I flew it. I did not have a good boost on a C11-5 engine. I got a St. Louis Arch to a lawn dart with the engine ejecting out of the back with a loud Bang! I'm wondering what diameter and length launch rod to use? I did not paint mine either." (H.W.H.)

[Enter Rocket Specific Tip]

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[Enter Flight Log]
Date Name Motor Ejection/
Wind Notes
01-26-2006 Hank Helmen Est SU C11-4 Very Late
(40 ft)
0-5 mph winds - St. Louis Arch flight, probably too short/small launch rod.
03-25-2006 Hank Helmen Est SU D12-3 Very Late
(123.5 ft)
0-5 mph winds Event: RAF field meet 2
- Third St Louis Arch for this vehicle! Ejection on ground. Shouldn't expect different results from same process. Seperated lower motor mount from wing. Second glider wing fractured at glue joint. Front glider broke body same place as previous flights.

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