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Goldberg/Brodak Shoestring Wing

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Goldberg/Brodak Shoestring Wing

Post  akjgardner on Sun Jul 03, 2016 8:16 am

I bought a Goldberg Shoestring kit from E-bay. The seller said he thinks all parts are there . When I received it , I found that all the wing parts where missing. My question is , Will the Brodak laser rib kit make a wing that will fit the Goldberg wing cutout slot ? Thanks for any help.
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Re: Goldberg/Brodak Shoestring Wing

Post  GallopingGhostler on Sun Jul 03, 2016 8:51 am

Don't know about Brodak, but you can contact him. Someone on Stunt Hangar or Stuka Stunt forums might be able to point you in the right direction. There ought to be someone out there who can laser cut ribs for you, who already has the patterns.

Outerzone has the plan, http://www.outerzone.co.uk/plan_details.asp?ID=6873. It shows the root and tip rib, so one could make up a kit if push came to shove.

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Re: Goldberg/Brodak Shoestring Wing

Post  getback on Sun Jul 03, 2016 9:33 am

Joe Hello , I got the plane CG that needs some attention and have been wanting to get down from upstairs , What are the measurements of the wing cut out ? Eric
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Re: Goldberg/Brodak Shoestring Wing

Post  Ken Cook on Sun Jul 03, 2016 10:10 am

The answer is no. In fact, I find it to be a extremely poor design. A perfect way to ruin a classic. The entire wing was redesigned. The outline is the same but the leading edge is a sheeted 1" leading edge with no strength . They also used too wide of a spar on the high point of the wing which doesn't sand out well which leaves a speed bump on the high point. It also is very susceptible to horse starving when sanded due to the lightweight sheeting. Unfortunatley, I spent last weekend smashing and jumping on planes that I felt I was never going to use again and one of them with a perfectly good wing was a Shoestring. Do you have the leading edge stock? Do you have the trailing edge stock? Do you have the wingtips? These are the toughest to replicate. Ken
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Re: Goldberg/Brodak Shoestring Wing

Post  Marleysky on Sun Jul 03, 2016 12:46 pm

Ken Cook wrote:The answer is no. Unfortunatley, I spent last weekend smashing and jumping on planes that I felt I was never going to use again and one of them with a perfectly good wing was a Shoestring.? These are the toughest to replicate. Ken

Awe man......that sounds just cruel. Didn't want to eBay 'em or offer them up to others for the cost of shipping??   Babe Bee

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Re: Goldberg/Brodak Shoestring Wing

Post  GallopingGhostler on Sun Jul 03, 2016 1:34 pm

I gathered that for an early 1950's design, very much Sterling S-1 Ringmaster like, probably flies similar to the Ringmaster. Over time, designers have found what works best, improved construction design as well as better and thicker airfoils.

Just like the Ringmaster, a few have revised for better building and flying. Not long ago, someone won or placed high in a large national CL contest with a Ringmaster. Goes to show that properly set up, the right pilot will make it perform.

Besides, not all us are competition minded. These are good sport designs. Back when they were selling in the 1950's to 1960's, they were decent performing machines, even with the cheaper quality kit wood and above all, affordable. Not all aim to fly picture perfect AMA patterns, it is the fun of flying that is more important, IMO.

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Re: Goldberg/Brodak Shoestring Wing

Post  Ken Cook on Mon Jul 04, 2016 6:51 am

George, many have used the Ringmaster in contests. Older designs of that era were handicapped as far as maneuverability. Too short of wingspan and thin airfoils were very typical. However, the Ringmaster while it also suffers the same fate, it can out perform pretty much all that was available back then. Another + was it's cost, they were cheap. Goldberg kits had a lot more engineering involved and the overall kit and instructions were superior to a Sterling kit. Sterling kits are just plain awful. The funny thing is the C-series Sterling kits offered  very clear and detailed instructions. Almost every Sterling kit builds nose heavy even using the lightest engine of the period. Many opted for no landing gear as this greatly assisted the flying ability. Not the case with a Goldberg Shoestring or Cosmic Wind or even the Buster. These planes are generally tail heavy requiring a bit of lead in the nose to calm down the twitchy flying. While both planes have identical wingspan, the Shoestring offers a thicker airfoil which just outright flies the plane better over the Ringmaster. The Shoestring offers a slight advantage having just a few more sq inches.
              What I did  notice is that the Shoestring can develop a case of BAD vibrations. This is due to the wing construction. The Shoestring has two ribs in the center spaced equally so that the fuse is directly over top of it. This void can transmit vibrations right back into the nose and leading edge of the plane. Making the center rib a solid 1/2" rib takes care of this problem and prevents leading edge and cheek cowling cracks.


Last edited by Ken Cook on Mon Jul 04, 2016 7:56 am; edited 1 time in total
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Re: Goldberg/Brodak Shoestring Wing

Post  akjgardner on Mon Jul 04, 2016 7:10 am

Thanks for the replies guys. I actually have another shoestring I can copie the ribs from, Just though it my speed things up if it where a good fit. Sounds like i will be making some ribs
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Re: Goldberg/Brodak Shoestring Wing

Post  GallopingGhostler on Mon Jul 04, 2016 10:36 am

Ken Cook wrote:What I did  notice is that the Shoestring can develop a case of BAD vibrations. This is due to the wing construction. The Shoestring has two ribs in the center spaced equally so that the fuse is directly over top of it. This void can transmit vibrations right back into the nose and leading edge of the plane. Making the center rib a solid 1/2" rib takes care of this problem and prevents leading edge and cheek cowling cracks.

Ken, regarding vibrations, for real shakers like the older Fox .35 stunt, I've gathered that this is why many prefer full body fuselages over profiles. They better dampen vibrations. However for me, I like profiles because they are so much easier to build. And yes, as you illustrate here, there are room for improvements to construction. But then, 66 years have past. As you pointed out, kits were cheap then. No doubt that a few compromises were made to keep kit prices down.

It amazes me how much the hobby industry provided much employment. Companies turned out kits in the thousands each week. Kind of reminds me of a song (words rephrased Very Happy )

sung to Paul Revere and the Raiders 'Indian Reservation' wrote:They took our whole C-L generation
Locked us out of parks in our nation
Took away our ways of flight
Unmuffled engines and the circles so tight.

Took away our right to fly
And taught our children kit building was nigh
All the kits we made and sent
Are now a day's make from the Orient

Plane building people, plane building tribe
So proud to live, so proud to fly!

But maybe someday when they learn
Control Line building will return, will return,
will return, will return, will return!

lol!

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