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Building Tips and technical articles. => Building techniques => Topic started by: Rob Killick on March 13, 2010, 02:15:06 PM
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Gentlemen ...
I've recently started my RSM "Shoesting" build and I've run into a snag .
Here's the condensed story ...
I talked to Eric Rule about the stunter and he recommended that I use the 7 oz. GRW700BU tank , rather than the plan recommended 6 oz. tank , as I'm using a RoJett .61 BSE RE with pipe .
He also said to remove the leading edge of the wing (where the tank will extend into the wing).
My concern is , how to reinforce the cut out , so as to not weaken the wing structure ?
The tank is as tight to the header as I wish to allow , without turning the plumbing into a nightmare .
Here's a photo , showing the set up ...
Thanks ,
Rob K.
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Rob,
I've only done this once but I used lite ply (1/8") and built a box to fit the notch in the leading edge. Glued in with epoxy, it held up the life of the plane. Just make sure you don't interfere with the B.C. movement.
James
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Hi Rob,
Do ya have enough room to make your own tank????? You can away make the tank thicker so it will hold more ounces and design the fuel tube to work with the motor. I believe that would be better than cutting the wing spar. I'm using a double star 61 RE lite case with my shoestring and it doesn't use as much fuel. Just a though and yes making a tank will work, Gary
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On my shoestring i went with a plastic tank. I removed some wood from the motor mounts to move the tank up a little. Worked perfect with room to spare.Super great flying plane one of my favorites. Used both 46 vf & ro jet 61
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In reality the strength of the center joint is derived from the spar and its joiner at the thickest part of the airfoil. The only thing you really need to do is box the cutout section in with firm 1/16 and maybe .5 oz glass to tie it all together.
I have my Kevlar suit on.
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Hi,
This is how I did to give more room for the tank, because had to shorten the nose moment to get the CG right due to a heavier engine (Saito .72) installed.
What you see is just a 1/8" medium hard balsa box that closes the notch.
And I agree with Ryan: the spar strength is what matters!
(of course, don't forget to glass the wing center section...)
(...and I have hostages! LL~)
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Do ya have enough room to make your own tank????? You can away make the tank thicker so it will hold more ounces and design the fuel tube to work with the motor. I believe that would be better than cutting the wing spar. I'm using a double star 61 RE lite case with my shoestring and it doesn't use as much fuel. Just a though and yes making a tank will work, Gary
Good idea, I like that a lot better than cutting into the wing. It's relatively easy to get 8 oz of fuel into 6" of space, if you make the tank 1 1/4" deep and as wide as the fuse will allow (with the RO-JEtt, that's about 2 1/8" or a little more). You will probably need to do something to knock off the front bottom corner to clear the header, but that's not too difficult.
Brett
p.s. this is the bigger of the two tanks I have used recently - 7.7+a little ounces 6" long. BTW, if you set yours up the way I do mine, the 61 will take about 6.5-6.6 ounces of 10% at sea level and 15% in the Midwest in the summer.
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Hi Brett,
I thought about installing a buddy tank, a small one ounce tank, open it up and solder it to the front bottom of the six ounce tank. I don't think you would have to do anything special, cause with the plane flying the force should push the fuel to the back of the tank. This might work if he doesn't have enough room to make the six ounce tank any larger. Might have to cut out some of the tank floor support. Just a dumb question but might work, Gary
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Hi Fellows ,
First , let me thank all of you for the help with the Shoestring tank , etc .
I'm going to build a tank (as per Brett Buck's suggestion) and with a tapered , or slanted front , it will fit nicely under the header , with just millimters to spare for th wing leading edge .
I've built a card(paper) model of the tank to test the fit , already . Now I'm pumped to make the new tank (just waiting for the sheet metal),
Thanks again,
Rob K.
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I thought about installing a buddy tank, a small one ounce tank, open it up and solder it to the front bottom of the six ounce tank. I don't think you would have to do anything special, cause with the plane flying the force should push the fuel to the back of the tank. This might work if he doesn't have enough room to make the six ounce tank any larger. Might have to cut out some of the tank floor support. Just a dumb question but might work, Gary
Not dumb at all. Both Ted and David have won NATs championships with the screw tops off of acetone can soldered to the bottom of the tank for more capacity. Works fine, the fact that it's asymmetrical is not an issue.
Brett