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T-18 Serial 649 N587 Restoration http://t18.net/thorpforum/viewtopic.php?f=36&t=8814 |
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Author: | Hagle347 [ Wed Feb 07, 2024 11:09 am ] |
Post subject: | Re: T-18 Serial 649 N587 Restoration |
There are 2 items of concern on the 'bob weight'. The weight itself should be sandwiched between the angle stock. AND the part should be straight - not 'adjusted'. Both point to the collar on the stab being installed at the wrong angle. I've seen that on another Thorp I was involved with on a much smaller scale . The result of this mod will not allow you to get the full and proper angle of up and down horizontal stab movement . That also negatively affects aircraft handing. - With regards to the front spar shims....were the rear spars shimmed as well? Keep posting and asking questions - We'll get it correct! |
Author: | James Grahn [ Wed Feb 07, 2024 12:03 pm ] |
Post subject: | Re: T-18 Serial 649 N587 Restoration |
I think it’s worth saving!! But I would return it to plans configuration. I’m not an engineer, but I can tell you that unintended consequences often happen with even minor mods. Those are not minor mods! Terry is right, the 510 might have been installed at the wrong angle. Not sure how to fix that. I would move the wing back to the normal position. With a fixed pitch prop, you should be right in the sweet spot of the CG. Cubes |
Author: | James Grahn [ Thu Feb 08, 2024 12:49 am ] |
Post subject: | Re: T-18 Serial 649 N587 Restoration |
Awesome! You do quick work. Cubes |
Author: | fytrplt [ Thu Feb 08, 2024 10:17 am ] |
Post subject: | Re: T-18 Serial 649 N587 Restoration |
A quick check of your stabilator and the placement of the 510-1 bracket may tell the tale. The 510 is to be installed 14 degrees 2 minutes slanted up from the horizontal axis of the stab. A not so uncommon mistake of the early builders was to install it at right angles to the stab. Many early builders were building ahead of John Thorp's final release of drawings. Several were being built in the Atlanta area and even had round fuselages. The fatal accident that resulted in the redesign of the horizontal tail was caused the bracket installation mistake and subsequent fix. The builder drilled out the rivets on 510-1 and correctly positioned it and redrilled the holes and re-riveted it. He essentially perforated the tube spar. A sharp pull up after a highspeed pass was all it took to fracture the spar. The spar doubler, redistributed bobweights, and the oh so important stainless steel straps on the tab were a result of this accident. If you make your way to Sun 'n Fun this year, I would be glad to meet up with you and show you my finished plane and the one I have under construction. I am based in Lakeland Florida. |
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