This is off a Grumman Cheetah/Tiger. Might have some clues as to Hoerner profile.
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| Wing Tips http://t18.net/thorpforum/viewtopic.php?f=3&t=8482 |
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| Author: | fytrplt [ Sun May 31, 2020 9:08 am ] |
| Post subject: | Wing Tips |
This is off a Grumman Cheetah/Tiger. Might have some clues as to Hoerner profile. |
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| Author: | Ryan Allen [ Sun May 31, 2020 2:10 pm ] |
| Post subject: | Re: Wing Tips |
Ah, I see the difference now in what I have. Thanks for posting |
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| Author: | hjubm2 [ Sun Jun 14, 2020 11:43 pm ] |
| Post subject: | Re: Wing Tips |
Has anyone built the Hoerner tips out of fiberglass? And if so how hard is the process? My tips are 40+ years old and the fiberglass is going bad so it might be time to replace the original tips with a new style. |
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| Author: | dickwolff [ Mon Jun 15, 2020 8:04 am ] |
| Post subject: | Re: Wing Tips |
Paul McMicheal in Seattle built a pair quite recently and he raved about the performance improvement. There is a good article in one of the newsletters describing how to build them. It may have been written by John Evans, but I’m not sure. |
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| Author: | Ryan Allen [ Mon Jun 15, 2020 9:15 am ] |
| Post subject: | Re: Wing Tips |
I would be all over buying a set of Hoerner wing tips if anyone has a set. As far as me building them, that's too much for my current fiberglass skill level. |
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| Author: | leewwalton [ Mon Jun 15, 2020 10:17 am ] |
| Post subject: | Re: Wing Tips |
Cubes sells them .. there's also a great 'how to' out there ... I can probably track down the exact newsletter. If I had to guess it's in the '90s era. |
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| Author: | Ryan Allen [ Mon Jun 15, 2020 11:46 am ] |
| Post subject: | Re: Wing Tips |
Didn't, think of Thorp Central. Well, I guess they will get some more of my money. |
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| Author: | dickwolff [ Mon Jun 15, 2020 4:29 pm ] |
| Post subject: | Re: Wing Tips |
Don’t hesitate to spend money at Thorp Central!!!! We need TC to stay in business. |
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| Author: | James Grahn [ Mon Jun 15, 2020 11:30 pm ] |
| Post subject: | Re: Wing Tips |
Our Hoerner tips are in the S18 profile. They would make a great start for someone who wanted them on a T18. All you would have to do is cut the splice about 1/3 of the way back, pull them down to the T18 profile, and reglass them. For the T18, we stock the original profile tips. Cubes |
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| Author: | Doug S [ Tue Jun 16, 2020 6:16 pm ] |
| Post subject: | Re: Wing Tips |
Tried to upload John Evens article but failed (maybe too big) Author date was Sept. 2003 if it helps. |
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| Author: | Doug S [ Tue Jun 16, 2020 6:39 pm ] |
| Post subject: | Re: Wing Tips |
Here's a drop box link https://www.dropbox.com/sh/o403ydna8v66 ... r6_Za?dl=0 |
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| Author: | pmandel [ Wed Jun 17, 2020 8:15 am ] |
| Post subject: | Re: Wing Tips |
Forgive my ignorance, but advantages of Hoerner on the T-18 are...?? According to https://www.aircraftspruce.com/catalog/ ... ngtips.php which is for C-150/172/etc: Typical Improvements are: • Increase cruise 3-6 mph • Increase rate of climb 75-100 ft./min. • Increase stability with more positive aileron control • Decrease stall speed 4-5 mph • Decrease distance for take-off • Gives a modern, more aerodynamic profile And according to https://www.eaa.org/eaa/news-and-public ... troduction -- "The result is a 5 percent improvement in cruise speed." (at least on a Sonerai, obviously much slower than our birds) Does anyone have actual numbers/advantages -- meaning measured, real world, not theory -- for the T-18? Please convince me that I want them. Very intriguing! (PS: My A&P would do all the modifying ("cut the splice about 1/3 of the way back, pull them down to the T18 profile, and reglass them"), fitting, painting, etc. I have zero ability in that regard, but he does.) |
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| Author: | jrevens [ Wed Jun 17, 2020 11:55 am ] |
| Post subject: | Re: Wing Tips |
FWIW - here is a portion of an email I recently sent to a couple of other Thorp owners... "There was no particular subjectivity in my testing of their performance. As I reported at the time I actually flew with one of the new and one of the original tips, with the new one on the left wing - the wing that normally was "heavy" with just me onboard, requiring a bit of the original roll trim (slightly lowering the position of that flap). Not only did I not need the trim, but I had to hold a considerable amount of left aileron pressure to compensate for what was obviously greater lift. It was surprising, right from lift-off, but increased as speed increased. Then I installed the other one and it was nicely balanced again. It's a little surprising and I have no explanation for it, but I saw no discernible difference in my full-throttle top speed - approximately 204 mph TAS at 7500' MSL. The biggest difference in handling was then during landing & especially when getting into ground effect... that extra lift was very obvious and I grew to like it a lot. I ended up lowering my approach/landing speeds quite a bit... seriously, about 10 mph. Richard Eklund had a friend who was quite a good metal-worker - I don't recall his name, but you probably know who I'm talking about. He & Richard carefully studied and took careful measurements of my tips one year at OSH. He then proceeded to build a set out of metal. They were very well done and matched the fiberglass ones pretty closely, except for a more rounded outer edge. He sold that first set to my best friend and hangar-mate, Dean Cochran. Dean put just one on at first, and performed the same test that I had. He actually took a spring scale up with him and measured the force needed to hold that wing down & level. I don't recall what it was but it was considerable, and he documented it in the newsletters I believe. Richard's friend later built a second set for Richard's airplane, and he confirmed similar results." I had enough Thorp time with the original design tips at the time to be able to make a good comparison of the new ones with my airplane. I can't attribute all of the decreased landing speed to the new tips, but they definitely made a very noticeable difference for me, making the landings more comfortable at those speeds. The level WOT speed referenced may have varied a couple of MPH one way or the other, but 204 is very close, with or without the "new" tips. 160 hp O-320-D2A and Aymar-Demuth prop. |
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| Author: | pmandel [ Fri Jun 19, 2020 10:35 am ] |
| Post subject: | Re: Wing Tips |
That is seriously cool info, John. Thank you. |
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| Author: | dickwolff [ Fri Jun 19, 2020 8:06 pm ] |
| Post subject: | Re: Wing Tips |
There is a series of videos on YouTube showing how to build Hoerner tips.... similar methods as what is described in the Newsletter article. https://m.youtube.com/watch?v=sDHynvw9Ozo https://m.youtube.com/watch?v=RoOh-fgI8oU https://m.youtube.com/watch?v=ULhZchv7ito D |
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