Bernt

[img]i/expressions/face-icon-small-wink.gif[/img] Help : looking for plans to build a Gremlin. Anyone know of a site, or the dimensions of this Combat plane.

Thanks for your help.
Bernt

Bernt

Helloooooooo
Wondering if everyone is busy?????????????


Can someone give me some idea????????


TX Bernt[img]i/expressions/face-icon-small-confused.gif[/img]

FHHuber

Sorry... been hoping someone had the actual dimensions handy.

I've built a Coroplast replacement wing for my Gremlin.. I don't remember if I exactly matched the original dimensions...

Wing:

48 inch span. EXCLUDING ailerons: root chord is 11 inches. Tip chord is 9 inches. Original Gremiln came with constant 2 inch chord aileron stock to be trimmed to suit the modeler. I've got 2 inch at root, tapering to 1 inch at the tip.

The fuselage is cut from 2.5 inch square PVC downspout. You can get a BUNCH of fuselages from the standard 10 ft piece of pipe sold at Lowes or Home Depot. [img]i/expressions/face-icon-small-wink.gif[/img] Overall, 19 inch length. The rear is cut off at an angle, bottom is 1.5 inches shorter than the top. The front is cut off in an "S" shape, the top of the cutout is 2.75 inch behind the front of the bottom. 9 inches back from the FRONT of the fuselage the top has a cutout, 9 inches long, that looks like someone planned on making a backward wing saddle for a fully symetrical airfoil. (If I remember, the original wing core just about fit that cutout at the wingtip...)

The fins are 7 inches lng at the base, 5 inches long at the top, 6.5 inches tall. The top rear is 10 inches behind the bottom front. 2 inch "chord" 3/8 inch thick (max thickness) taper TE stock is used as a spacer/angle guide for mounting the fins. The bottom rear of the fin should be directly over the elevon hinge at the fuselage.

The fuselage mounts to the wing with the base on the line from center of LE to center of TE (stock core) in a channel cut to fit the width of the fuselage. The balance is achieved by moving the fuselage (thus the engine and radio ) forward and aft (fins go on AFTER balance is figured) Correct CG is appx 1.5 inches from LE. (NEVER go back to 2 inches! its uncontrollable at that point.)

Control throws need to be slightly lower than you might expect. Its very sensitive. 20 deg up or down at max deflection is plenty. Initial launch should be with appx 1 to 3 deg up elevator (use the trim tab... about 3 to 4 clicks from neutral)

Full power with a .40 using a 11X4... it will go straight up indefinitely. They fly fine with a .25 using a 9X5 built from the "RA Cores" ( http://www.racores.com/ ) kit. The coro wing version needs a .40 to .46.

The kit is still available... Not a bad deal really.


That's enough info to build one.

Bernt

Thank you, thank you, thank you have to something with my time.


Bernt

dan v

Correction:
The rear bottom is .5 in. shorter. The angle is 67 degrees

dan v

I was wrong. The rear bottom is 1 inch shorter, or 69 degrees

MartyH

My Feedback: (16)

For $35 you can have a genuine Gremlin AND support the people that took the time to develop and bring it to us in the first place, RA Cores.

Propworn

My Feedback: (3)

Can you cut foam cores? If so I have a simple wing that out fly's the gremlin on a .25

aspeed

http://pulling-gz.blogspot.ca/2013/0...-gremilin.html Only took 12 years to find. Lots of other stuff too. Not a lot of dimensions.

jahatton

http://pulling-gz.blogspot.ca/2015/0...-and-plan.html

MartyH

My Feedback: (16)

What is this flying wing you are suggesting is better than the Gremlin. Do you have templates? that's a good looking wing.

Marty

Propworn

My Feedback: (3)

This is my own design when we flew combat everyone was using the Gremlin. This thing flew faster, turned harder and just out flew it period. Soon all the guys in the club were flying them and if you wanted it even more agile just lop off 4 inches on each wing panel. No need to rebalance the CofG adjusts to the new wing span. We were using Norvel .25 with an 8X4 APC and someone clocked it at over 100 mph. Somewhere I have the plans I can look it up and run you off a copy. Its a pretty rough drawing maybe even in magic marker.

Dennis

Propworn

My Feedback: (3)

I was asked to design something similar but for radios without mixing and no sliding servo tray. http://home.cogeco.ca/~denpratt/My%2...t/piranna.html

All my combat were white then as collected mid air victims I added the red blood to the wing. I cannot remember how many I flew right through with very little damage to the Wedgie. Its a foam wing fully sheeted with 3/32 balsa and later with 1/32 ply and carbon.

A good Norvel could turn an 8X4 APC somewhere around 15,000 on 15 to 20 %nitro.

Dennis

aspeed

Dennis, did you use tape hinges in post # 8? or was that just a mockup? http://www.spadtothebone.net/SPAD/si...torversion.htm that is another method of going with not mixing. A torque rod from the ailerons to the centre and then a horn on the elevator works. I haven't really tried it, but seen it on "For What It's Worth" a long time ago. The Spad To the Bone site has a bunch of cool stuff too. I am just making a couple right now. Saturday night Midget with a .15 should be a hoot.

dan v

His wing may out fly a gremlin but- The gremlin is also a nice slow flyer and no tip stall. I have 2 of them and they are way fast enough w/.46 OS or .35 OS max engines.
We had my .35 on my gremlin and came up w/131mph. Martyh built a nice wing. i'll stick w/gremlin.

Propworn

My Feedback: (3)

The control surfaces were taped on only for the mock up of the first one to get the control movements and geometry correct. The actual finished hinge line was the iron on covering. One inch wide the whole length of the control surface ironed on top and bottom. The aileron leading edge needs to be shaped tapered to the top edge for top edge hinging. I lay the aileron upside down on the top of the wing lined up edge to edge and iron on the one inch bottom strip. I then flex it down to maximum down holding it edge to edge and iron on the one inch top strip. When I cover the rest of the wing I do not go over the hinge again but cover up to the hinge line. No binding works like a charm never had one ever come apart even in the most violent of mid airs.

The University of Windsor liked the performance of the flying wing design so much they used the same configuration with a different airfoil for heavy lifting to compete at the Lockhede Martin SAE Aerodesign contest http://imageevent.com/sunparlorflyer...b349f3.eagle_s

On this model as well it was the covering that provided the hinging.

Dennis

Propworn

My Feedback: (3)

Well we flew a lot of Gremlins and they were prone to tip stall if you got them to slow. The model was designed for a .25 and flying competitive combat we tried many different engines and prop combinations. We found in every case the heavier engines made the thing fly worse. The heavier they got the worse the tip stall and the worse the tendency to snap under high G maneuvers. With the bigger motors they did not fly any faster and were less maneuverable. Those with larger engines couldn’t compete with the lighter ones. We could out turn them and because we were turning more rpm and lighter could out climb any of the 40/46 versions. The weakest part of the Gremlin was that downspout. You always had to have extras as the plastic was non repairable if it split which it had a tendency to do.

The Wedgie on the other hand with the sheeted wing and integral motor mount box glued into the model was much more durable. These were much lighter and more streamlined than the Gremlin as a result were faster with unlimited vertical acceleration. The wing tip fences allowed you to drag it in with the nose bobbing in a stall without dropping a wing something you could never do with a Gremlin. If you tried it with a Gremlin it would roll over like a shot duck and do a dirt nap.

As to the OS .35 going faster than the Norvel .25 I have a hard time believing that as some at our club went the bigger engine route and gave it up. To reach even theoretical speeds of 130 mph with no slippage you would need an 8 inch pitch prop at 17,000 rpm something an OS .35 is just not capable of and still stay in one piece.

The Wedgie with the Norvel was over a lb lighter.

yankee samurai

My Feedback: (175)

If it's so great how about sharing some spec's so others can build one?

Propworn

My Feedback: (3)

I'll ignore your sarcasm I will have to look up the prints.

Dennis

Propworn

My Feedback: (3)

Found the prints they are old first generation I can describe the changes that were made that made it even better. What is it you wish to know Grasshopper?

aspeed

Similar to a Stryker. They are pretty good. I remember seeing your other heavy lift plane go. 25 lbs. with a .61 was pretty good. It seemed like it would be impossible to even move it on the grass when I lifted it up, much less fly.

Propworn

My Feedback: (3)

Thanks for the compliment on the heavy lift project it was fun, the plane weighed 7 lbs at 1000 square inches and it lifted 23.5 lbs for just over 30 lbs all up. Wish there was enough interest to do it again.

The flying wings that work well are all very similar. Optimizing the wing loading with control deflection to get maximum speed and maneuverability was the priority for this one. As a result the later improved versions had a combination motor mount/fuel tank assembly instead of separate. As the electronics and servos got smaller the doghouse on the back was dropped and everything was inside the wing cleaning it up considerable. The wing tip plates became smaller and most changed them to a profile that personalized them.

The biggest innovation was finding out that once built and flown you could remove the tip plates and shorten the wing up to 4 inches a side and just reapply the tip plates and fly without having to readjust for the CofG. The plane flew the same except the roll rate increased dramatically again increasing the maneuverability. We actually tried reducing the span even more but performance started to suffer so we settled on a 40 inch span down from 48.

Dennis

yankee samurai

My Feedback: (175)

How much for a copy of the plans?

Propworn

My Feedback: (3)

As you noticed I live in Canada and the cost of copying is silly. I can walk you through it step by step with the improvements. Its really very simple. Do you have access to a foam cutter?

Dennis

dan v

The 131 mph was not theoretical, was on radar. But this is how I did it. Went to a high split S, hammered the throttle all the down then cam across the field.
All I'm really trying to say is it's hard to beat the Gremlin for a $35.00 plane. I beef up the front ends of my Gremlins. I put plywood under the fuse where the motor mount is and cover the front in epoxy, sheet w/ fiberglass.
Happy flying
Dan