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Twin Needle Thermal Hopper with a Cage Mount.



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Post  rsv1cox Thu Oct 21, 2021 1:04 pm

Hitched up a coat hangar trial bridle.

Big Brother - Round one P1011890
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Made a CG finder out of a dowel, piece of string, and a clip

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Perfect CG
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Not so perfect CG

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No matter we are going to crank this thing up and see what happens.  I had bench tested all three Golden Bees last week, and all ran very well.  Not today, nose GB would not start past the prime.  Swapped out with the right side GB that started right off.  Plan is to do a circle with just the nose engine running then add the other two.

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Didn't happen, went hard right against the tether line.  Got adjusting to do.

Mark came up with a good idea. Bend the bridle as shown with two interior wheel collars and adjust inward until the sweet spot is found. Saves a lot of bending and trial and error.

Big Brother - Round one Scan_103
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Post  davidll1984 Thu Oct 21, 2021 3:30 pm

As I went down the page I thought That we were going to see her in action bounce Flying The idea with the collars is good Thumbs Up Can't wait to see it in action Biplane
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Post  Yabby Thu Oct 21, 2021 3:56 pm

Same, and now we know how much it weighs, I reckon its really going to go! with three engines all running! Keen to see or hear how it goes. :-)

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Post  NEW222 Thu Oct 21, 2021 4:15 pm

Fingers crossed in anticipation here!
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Post  rsv1cox Thu Oct 21, 2021 6:18 pm

Everybody is way to optimistic  - this thing ain't gonna lift off the ground, much less fly.  We are talking over two pounds of dead weight here.  

It might IF I remove the pontoons and replace with a tricycle landing gear assembly.  Lot's of drag on those four wheels and the two front wheels fight each other in the turns, and it's all just one great big turn.  I am thinking about removing the two front wheels and replacing with a single wheel located in the middle of the front axle.  

My goal is to get it to go around in a circle, if it does lift off I will be happy to eat my hat.  

Bob
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Post  Cribbs74 Thu Oct 21, 2021 7:50 pm

I am not entirely sure what Mark is talking about but my thought is to mount the bridle so it yaws outward. Maybe that is what Mark was saying.

Another thought would be to dial some drag into the outboard wheels.
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Post  rdw777 Fri Oct 22, 2021 3:27 am

You might try canting the the wheels to naturally follow the arc of the circle instead of rolling straight….. Probably most efficient if done both front and back…. Bridle adjust should help too…Watching…. And good luck!!
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Post  rsv1cox Fri Oct 22, 2021 7:39 am

It's all about the center of gravity, or in this case - the center of pull.  Rolling resistance too.  I replaced the two front wheels with a single larger wheel and it reduced the rolling resistance dramatically.  One finger push now and it just rolls.  

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Tried a Cox Mercedes tether car with just a single point of attachment for the bridle.

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Begs the question - why not just epoxy an eyelet into the cg point of the lower wing......................

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Post  rsv1cox Fri Oct 22, 2021 8:18 am

@Cribbs74 wrote:I am not entirely sure what Mark is talking about but my thought is to mount the bridle so it yaws outward. Maybe that is what Mark was saying.

Another thought would be to dial some drag into the outboard wheels.

That was the problem, it yawed outward too much as the center of pull was wrong. It just headed out from the circle crabbing instead of staying parallel to it. Moving the center of pull forward toward the nose will cure that.

I had thought about inducing drag into the outboard wheels (if it tended to come in on the tether line) by adding silicone tubing between the pontoons and the wheels and adjusting compression.
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Post  getback Fri Oct 22, 2021 8:37 am

Yea Bob , as usual there are adjustments to bee made , I think the single wheel in the front looks better anyway . That CG with the eyelet may be the trick (sounds good anyway ) Laughing Popcorn I Love This Forum! Does Mark have a YouTube acct? If so why not get him to video the action and post ,, If he is there of coarse .
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Post  rsv1cox Tue Oct 26, 2021 12:34 pm

Found out why the Golden Bee wouldn't run.  No venturi gasket.  I think I built this engine from parts with a later plastic backplate that has vents, not a problem on this as it won't be doing any loops.  

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Replaced the gasket and working on struts.  Lot's of different styles, V's, N's, but I came up with my own - call them H's Smile  Experimental trial fit.  Paint to follow but won't put them in until I have ran it a couple of times.  Thinking about removing the bridle and just tethering it with the wing eyelet unless someone has a better idea.  

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Neither one of us have a youtube account Eric, maybe there is another way to post a video.
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