Building a Comet 54" Chief from Volare

[randoloid]

Always wanted to build a big rubber powered plane and am nearing completion of the Comet Aeronca Chief from Volare. 

Was wondering if it would fit any class for outdoor competitions.

I live in the mountains of VA where the fields are small and the trees are large. I'll definitely be taking it with me when I go to some competitions, even if I only fly it for fun.

Just wasn't sure if it would fit into a class-  Although it's based on a real plane, I've designed my own livery so pretty sure that rules out scale. 

Don't think it's old enough for old time. and really was just curious about that. 

[bcarter1234]

Please post some images and let us know what test glides and trimming are like. I hope to try something that size at least once but I would probably be intimidated by winding it. ;-)

[One Cut]

It should qualify as giant scale or the other fac large scale.  Not sure about doing your own livery though.  That has always been a problem for me, to have a model done up like I would want the real one to look if I owned it, but have it not accepted because I can't document the finish. 

[Jmk89]

IMHO in this case, it qualifies to compete but to the extent that the finish cannot be supported, it should not get any points for accuracy of finish. In that case, you should be allowed to enter but you have almost no chance of winning. However, if the rules of the relevant contest require that your documentation include a photo of the actual plane modelled, you should ensure that you use the registration shown in one of your photos - in that case you can say that you satisfy the requirement, it's just that you did a lousy job with the finishing!

As a final thought, what a ripper idea for a contest! Scale except for finish accuracy with finish judged on visual appeal and quality.

[randoloid]

Thanks all for the comments.  I was just curious, and in any case if I could get it accepted in some sort of scale class, I'd still have nearly a zero chance that I could place / win... My builds aren't any where close to other builders scale details. (and I'm totally okay with that).

I'll just keep this one in the "fun of flying" category and enjoy the plane.

I've started covering it this weekend so including an obligatory progress pic.  Should have chalked the white tissue, but oh well.

[OZPAF]

That looks great! It's a very effective scheme and the tissue printing is very sharp.

I'll just keep this one in the "fun of flying" category and enjoy the plane.

That sounds like a good idea to me.

What size prop and rubber motor does this beast need?

Happy building and flying.

John

[bcarter1234]

That looks fabulous. I look forward to watching it progress.

[randoloid]

That looks great! It's a very effective scheme and the tissue printing is very sharp.

I'll just keep this one in the "fun of flying" category and enjoy the plane.

That sounds like a good idea to me.

What size prop and rubber motor does this beast need?
Happy building and flying.

John

Using a 17" 3d printed prop and will use 5 loops of 3/16

[randoloid]

I'm progressing on my build and would love some opinions / guidance on the motor.

The plans note: 17" prop and 5 loops of 3/16 Rubber.

The build weight target listed on the kit makers website list 130-150g. My weight without rubber should be right around 140g

Distance motor peg to hook is approximately 18"

I made up a motor of 5 loops at 2x 18" (36") and then braided.  The braided motor is right at the 18" of the peg to hook measurement.

I know there are challenges weighing a rubber motor with a digital scale but I attempted to insulate the rubber and I weighed before braiding. Total weight was 45G which seems like a good size for the weight of the plane. 

Realize this is a lot bigger plane than I've ever built / flown but something doesn't feel right-- when winding the braided motor the torque climbs really quickly and even 400 turns feels like it's getting close to Max - This is just going by feel, I don't have a torque meter.  I would think that I'd need a longer motor run - for a really nice flight.

I guess I should start here and see how it behaves but thought I'd ask others to share their knowledge.  Should I go with a  longer length to get a longer run time?

[calgoddard]

"I made up a motor of 5 loops at 2x 18" (36") and then braided.  The braided motor is right at the 18" of the peg to hook measurement."

This statement is confusing. What is the cross-section of your braided rubber motor? In the photo you posted it looks twice as thick as it should be.

The 45 gram weight sounds about right.

The rubber motor can easily be 2 x the hook-to-peg distance if braided without rubber motor bunching problems, provided that you use a wobbly motor peg. The latter is a length of Aluminum tubing held in place in the rear ends of the loops that has an ID that is slightly larger than the OD of the motor peg. As the braided rubber motor unwinds the wobbly motor peg rocks back and forth on the motor peg and reduces and/or eliminates rubber motor bunching that leads to CG shifting and diving or stalling. Braiding is needed because it helps the rubber motor form "grapevines" which are evenly distributed along the length of the rubber motor once it is completely unwound.

[cvasec]

5 loops of 3/16" 36" long would have a max number of turns of about 1250 so it should be good for 1000.
Ron

[Stunthenk]

How much larger should the alu tube of the wobbly motor peg be compared to the motor peg? And how long (or wide, seen from above) should it be? About as wide as the fuselage at the motor peg station or narrower?

[calgoddard]

The wobbly motor peg just needs to be able to rock back and forth on the motor peg that it surrounds. In the attached pictures the motor peg has a 1/8-inch OD and is surrounded by what is probably a 3/16-inch diameter wobbly motor peg. Both are made of Aluminum tubing. The length of the wobbly motor peg just needs to be large enough to hold the loops of the rubber motor. A dental rubber band surrounds the rubber motor at the end and is cinched up tight to the wobbly motor peg to hold the loops in place. I usually flare the ends of the wobbly motor peg by inserting Philips screw driver tips at each end and suaging the Aluminum tubing. The flared ends of the wobbly motor peg help retain the loops of the rubber motor in place.

For larger models like the 54-inch Comet I would use a larger motor peg, with an OD of 1/4-inch. The wobbly motor peg would then be a shorter segment of 5/16-inch or 3/8-inch OD Aluminum tubing. The latter OD may be a little too large and I would need to check my inventory of rubber motor parts for my large Old Timer Rubber (OTR) ships to confirm the appropriate diameter of the wobbly motor peg that is used with a 1/4-inch OD motor peg.

You will need to fashion the ends of your stuffer stick with flanges that are suitably spaced apart and with appropriate size circular recesses to hold the wobbly motor peg.

Aluminum tubing of these sizes is available in the US from K & S Metals.

[Stunthenk]

Thanks! I think it would help if the stuffer stick with the motor on the wobbly tube would engage positively in the location of the motor peg.

[randoloid]

"I made up a motor of 5 loops at 2x 18" (36") and then braided.  The braided motor is right at the 18" of the peg to hook measurement."

This statement is confusing. What is the cross-section of your braided rubber motor? In the photo you posted it looks twice as thick as it should be.

I made 5 loops @ 36" and braided it down to 18". 

I agree it looks awfully thick. 

And Yes I'm using a wobbly peg to keep the motor from bunching- My motor peg is 3/16 and I 3D printed a 1/4 ID bobbin