Yet another C RC-Rocket Glider

Since the contest season is just around the corner I though I would create another new C-RG for the regional and NARAM 56 events. My RC Boost Glider version worked fantastic but this design would not allow me to use the new Aerotech long burn 18mm reloads they’ve recently came out with. My C-RG designs needed to much work getting them to boost straight so I am going to use the shorter wingspan of the BG with the same tail section and use a new body design that has the motor tube simply mounted on top of a pylon up front in the same location as the BG had. I will try to keep the weight low on this version and if it flies good I’ll make another one for a back up.

Basically the entire structure is 1/16” sheet balsa, with 1/8” balsa sticks in all the corners and wing saddle locations. The Formers are all cut out of 1/8” Light Ply. I will cut out a hatch at the lower front of the model just like I did with my other full body design. The pylon at the top front of the model looks kind of small but the upward slop of the body hinds the fact that it is much higher then the wing location. As seen in the photo the fuselage and pylon weigh in at 14.4 grams.

John Boren

Interesting shape. Is there some angle in the motor pylon or are you just relying on the distance above the wing to counter the wing lift on boost? Hard to tell from the 3/4 top view?

kj

There is NO angle in the motor pylon. None of my BG models have angles in them so I went this route. I can always modify the pylon if needed after test flying.


John Boren

Hope it works for you that way, but I'd expect for an RCRG to have a little angle there to cancel out the wing lift and provide for more hands off boost. BG's don't normally need it due to the pod mass. It doesn't have to be much, more than 2-3* and you'll be fighting to pull up.

kj

BG's don't normally need it due to the pod mass.

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I'm sure your right. I'll start with 1 degree of thrust angle instead of zero degrees.

John Boren

The photo's look like a boat keel. It will be interesting to see the final model. The bulkhead plates look like you have access to a balsa laser cutter.

I've been meaning to ask: what laser cutter do you use and how do I get one?

Great work as always.

what laser cutter do you use and how do I get one

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You can send you files off to a number of companies that will cut parts from your files. All of these parts can in fact be cut out at home if you take your time. China produces some very cheap 5K to 7K laser cutters. The only issue is getting it here.


John Boren

Ah. I always figured you had one in your basement. Currently, I have access to one at my school, but I'd like to get my own at some point. Maybe even make one.

What wall thickness are you using for the slab sides?

What wall thickness are you using for the slab sides?

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I am attempting to make this model light for competition flying. All the sheet balsa on the model is 1/16". The body is very rigid. I will tissue and dope the fuselage and tail feathers for added strength.


John Boren

Today I cut out to blanks of 3/16” balsa for the two sets of wings I plan on making. I screwed up and made these wings 2” shorter in span then I wanted so I will most likely make a second set on longer wings, fly both and see which ones I like better. The wing has 90 square inches of area. As seen in the photo the model comes in at 40 grams. I still have 11 grams of radio gear, tissue covering of the fuselage and tail sections, pushrods and other stuff before this model is complete so I’ll make a guess and say it will come out at 60 grams ready to fly minus motor.


John Boren

I decided I needed to make a bigger wing for my C-RG so I wiped this thing out. Not Really. I figured I would build the Estes “Sweet V” I’ve had in my basement for almost a decade now. I have a love hate relationship with the Obeche wood sheeting use to cover the foam core panels.. You look at this stuff wrong and it chips, splits and just causes you all kinds of head aches, but once it’s down and sanded smooth its great stuff plus there are NO seams to worry about. The foam cores in the kit were cut real nice except for the fact the root cord of the tip panels didn’t exactly match the tip cored of the inner panels. I’ll putty things up a bit to blend them in before fiber glassing each joint. I plan on flying this thing before and during NARAM sport launch days. If it flies well I may even let others fly it, if there is any interest.


John Boren

JumpJet said:

Today I cut out to blanks of 3/16” balsa for the two sets of wings I plan on making. I screwed up and made these wings 2” shorter in span then I wanted so I will most likely make a second set on longer wings, fly both and see which ones I like better. The wing has 90 square inches of area. As seen in the photo the model comes in at 40 grams. I still have 11 grams of radio gear, tissue covering of the fuselage and tail sections, pushrods and other stuff before this model is complete so I’ll make a guess and say it will come out at 60 grams ready to fly minus motor.

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John, how do you hold down the win and what radio are you using?

I have an older thread showing my first, second and third go at this. the wing gets held down with a 4-40 nylon bolt. The radio is taken out of seires of micro airplanes produced by Hobbico\Great Planes.


John Boren

My new C-RG is about 98% complete. I just need make a battery extension since the battery is now located under the trailing edge of the wing to help get as much weight towards the rear as possible. I will most likely still need to add 3 or so grams in the tail to get the final CG but I’ll need to do so test glides first. Usually always need to add weight in the nose but I underestimated how much the empty engine weight was going to change things being so far forward. I glade I made replacement stab parts out of 3/32” balsa instead of the original 1/16” balsa. I also made a new wing so I have 100 square inches to support this bird. Right now with the reload casing in place but without it’s burnt out reload remains in place the model weights in at 85 grams. This is a full 10 grams heavier then by C- BG model that has the same size wing. Hopefully the composite C3 motor will put this model up a lot higher, plus it is a much cleaner flying model since everything is inside. My final choice between the two is going to be how well the new RG boosts since the BG boost perfectly straight up.


John Boren

Got the Estes Sweet V all framed up, covered and painted. Now I just need to install a radio.


John Boren

Cool colors on the Sweet-V. What do you plan to fly it on?

Also, I'm pretty sure it's an optical illusion, but the left wing looks like it has a ton of excess washout in it.

ton of excess washout in it

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Just an optical allusion as you stated.

Might try some E12 motors, not sure at the moment.


John Boren

JumpJet said:

Got the Estes Sweet V all framed up, covered and painted. Now I just need to install a radio.


John Boren

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Just friggin BEAUTIFUL !!!!

I finally got around to test flying my new C-Rocket Glider. I didn't have to add and weight to the tail or nose. First flight was on a C6-0. Straight Boost,lost it in the sun since thats the direction the wind was coming from, never needed to touch the stick on the way up. It flew for just under 2 minutes. Second flight I used one of the those new Aerotech RMS C3 motors. The first couple of hundred feet was straight as can be then it slowly pitched up by this time it was right above my head so I had to do a 180 to see it and gave it some inputs that most likely didn't help but it still flew straight enough. I was standing way to close to model, so next time I'll step back quite a ways so I'll have a better view. It flew for only 1:20 on this flight but i was messing around more with the trims to find just that right glide speed and not trying to find lift. I think two clicks on down trim would result in a straight hands off flight from start to end. Although it flies fine I think I'm going to make another longer span wing to get the wing loading down a bit. I wan't this model to be a real floater.


John Boren

Do you launch it from a special pad or just a normal rod?

I made a special pad for it with four carbon rods that go along side the fuselage and top and bottom of the wing to guide it.


John Boren

I flew this model twice more with the new AeroTech composite C3 motors and it boosts as good as one can hope for. I am very please with this design although I do plan on making another wing with greater span to get my wing loading down.

John Boren

Today I built myself a larger wing for my glider. My old glider wingspan is 25-5/8” long with 99.68 sq. inches of wing area and weighs 26 grams. The new larger wing has a wingspan of 33-1/2”, contains 138.8 sq. inches of area and weighs 33 grams. I’ll take this increase in weight any day for higher the aspect ratio wing and 38% more wing area. The only issue is will it stay together during the boost.

One image shows the new wing covered in a clear heat shrink plastic. The covering material added 7 grams of weight. I'll shoot a light coat of color over the wing which may add another gram or two. The other images shows the old wing laying on top of the new wing.

John Boren

That's so cool!! Great job!!

Nice work. I hope you post a flight comparison of both wings used on the same day to see just how much difeerence there is between the two. I have not seen a comparison of such and would like to know the effect of going bigger. Hieght loss vs extended glide etc.


Richard

I did a test flight today of my new wing down here at a regional in New Mexico. The wing was fluttering like crazy during the boost. Luckily it glided back just fine but I won't be flying that wing again unless I can make some major changes to stiffen it up.


John Boren

Since I really want to use this larger wing I decided to add some cross ribs to stiffen it up. It appears to be much stiffer now and hopefully once it's covered it will be good enough to withstand flight loads.

John Boren

I hope you post a flight comparison of both wings used on the same day to see just how much difeerence there is between the two.

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Not sure if anyone is still interesting about this model but I flew the new larger crossed ribed wing today. It still fluttered going up, although not as bad and since I had some down trim in it at lift off and I needed to pull up to get it going straight up it only got maybe got 300 feet of altitude. Once in the glide the new wing was FANTATIC. I got 2-1/2 minute flight without really trying. It's the difference between gliding and soaring is the best way to describe it. I then mounted my smaller wing took out the down trim and flew a second flight within 5 minutes of the first fligt. This time straight boost to 600 plus feet and I was down 1-1/2 minutes later. This small wing glides fine but it simply doesn't soar. So now I need to see what I can do to make this wing stiffer while at the same time making a completly new wing out of foam and fiberglass.


John Boren

JumpJet said:

So now I need to see what I can do to make this wing stiffer ....

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I'm no free flight builder but I've read of a technique of applying carbon fiber tow across the tops and bottoms of the ribs in things like B and C Gas models as well as some of the more energetic rubber-powered models.....of course you'd need to strip the covering off to do that.

Perhaps a stiffer covering like Litespan?