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  #1  
Old 05-16-2010, 02:30 PM
GlueyFingers GlueyFingers is offline
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Default Suggestions on upsizing/downsizing sky dart?

Anyone able to offer suggestions on how much to upsize / downsize the sky dart plans to either fly to limited altitudes on a C6-3, or fly at all on an A4-3T? I'm rolling the body tubes anyway, and it's easy to print the wings at any scale...
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Old 05-16-2010, 03:09 PM
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georgegassaway georgegassaway is offline
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To fly to a limited altitude, you say?

How about, build it to 100% scale, and fly it on a B6-2?

OK, how about scale it to 133% to use BT-55 tubing?

- George Gassaway
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  #3  
Old 05-16-2010, 04:04 PM
GlueyFingers GlueyFingers is offline
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Thanks, I may go with something around the 133%

Is there any particular advantage to the side ports of the boost pod with internal weights, vs. an open end and taped on weight around the outside? It seems like this would be less likely to suffer burn damage.
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Old 05-16-2010, 11:26 PM
AstronMike AstronMike is offline
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Quote:
Originally Posted by GlueyFingers
Thanks, I may go with something around the 133%

Is there any particular advantage to the side ports of the boost pod with internal weights, vs. an open end and taped on weight around the outside? It seems like this would be less likely to suffer burn damage.


If you do use an 18mm pod within a BT55 main body tube, then by all means tape/glue your pod weights on the outside of the pod since there is plenty of space for this. That bit of 'vent holing' a pod with weights filling the end usually results in the pod breaking or plain blowing apart upon a nuclear ejection charge (prevalent nowadays).

As far as upscaling goes, I currently have a BT-70 based SkyDart, which does well on E15s and 24/40 loads. Have many other gliders even larger, but not exact SD scales.

One good way to make your 55 upscale easy is to use Adams Readiboard for the wing/rudder surfaces, this is available at Dollar Tree. Cheap, and lighter than the balsa youd normally use. Also, you can just notch the underside of the rudder, as in the original SD plans, and have the elevator hit this for your stop. Just make the elevator raise only about 1/4" to 3/8", assuming youre ending up with a BT55 scale version. May have to add some glider nose weight for final trimming or 'dam' the elevator with a paper clip on the rudder.

Another good size to work with is a BT60 version on a D12, which I also have and flies well enough. You may well consider this instead as it looks 'meatier' enough.
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Old 05-16-2010, 11:37 PM
GlueyFingers GlueyFingers is offline
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Think I will stick with 18mm engines for now, but the readiboard is an interesting idea, do you use it as is or remove the paper?
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Old 05-17-2010, 12:37 AM
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rokitflite rokitflite is offline
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Quote:
Originally Posted by GlueyFingers
Thanks, I may go with something around the 133%

Is there any particular advantage to the side ports of the boost pod with internal weights, vs. an open end and taped on weight around the outside? It seems like this would be less likely to suffer burn damage.



I prefer to build my internal pods with a baffle system. This prevents the extreme build-up of ejection charge "gunk" on the inside of the glider body. No "gunk" means that the pod will fit the same from flight to flight and there will be no damage to the inside of the glider.
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Old 05-17-2010, 12:41 AM
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Old 05-17-2010, 06:31 AM
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gpoehlein gpoehlein is offline
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Quote:
Originally Posted by rokitflite
I prefer to build my internal pods with a baffle system. This prevents the extreme build-up of ejection charge "gunk" on the inside of the glider body. No "gunk" means that the pod will fit the same from flight to flight and there will be no damage to the inside of the glider.


I did something similar with my BT-60 upscale (I used the stormcaster nose cone on it). I've flown it twice on a D12, but I still haven't got it balanced quite right. Inside the boost pod, I put a hunk of stainless steel "sponge" - a bit heavier stuff than steel wool intended for cleaning that I purchased at the grocery store. It catches the ejection debris just fine.

Greg
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Old 05-18-2010, 09:38 AM
AstronMike AstronMike is offline
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Quote:
Originally Posted by GlueyFingers
Think I will stick with 18mm engines for now, but the readiboard is an interesting idea, do you use it as is or remove the paper?


No, just use it as is. In fact, the Readiboard uses a real paper coating that glues very well, whereas standard foamboard usually has the clay based coating.

Since you want to do the BT55 version on just a C6-3, heres a few hints along the way:

1/ Try to use the lightest NC you can. Now, if you wind up using a heavier NC, this isnt totally bad even if you need more elevator deflection to induce glide. However, a thin plastic NC usually results in a glider needing less deflection - and therefore a better glide.

2/ If you do use a plastic NC, try to cut out most of its shoulder. This has two plusses. First, you save some weight on the glider itself. Secondly, you get more room up inside the NC for the pod to extend into, meaning a given amount of ballast gives more moment effect.

3/ If you wind up with a heavier NC that you must use, you can sort of compensate by upscaling the elevator a bit beyond 1.3x. Span better than chord for this.

4/ No matter how well and light you try to make this, it will be draggy and pretty stout for an 18mm motor. Great for smaller fields and impressive. Since the Quest C6-3s do not lift well, I do not recommend these, even though I have a glider actually a bit larger than a 1.3x SD that does well on those. Not to mention, you get three 'real seconds' of delay, and that is loooong if you get an arced boost and its coming in hot from apogee.

5/ Elevator hold down clip: Just use a paperclip bent just right and taped to the rear of the pod. I do this for all sorts of gliders, and even up to HPR ones.

If you keep the weight down this should be a perfect reasonable flyer.
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  #10  
Old 05-18-2010, 10:23 AM
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ghrocketman ghrocketman is offline
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Those neubauer sky dart semi-clones are a real bargain...
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