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Thread: Thorp

  1. #1
    Mike Switzer's Avatar
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    Thorp

    I have been working on designing my own plane, but I am beginning to realize that this is going to be a long process, & I want to be building now.

    It appears that a Thorp S-18 would come pretty close to satisfying my needs (although I would like a little more baggage capacity, but that is not a deal breaker)

    Most trips would be 2 guys 6'2" - 6'4" with wide shoulders (the reason for looking at the S-18 over the T-18), the heaviest pilot/passenger combination would be around 500 lb.

    According to the data on this page
    http://thorp18.com/forum/default.asp?CAT_ID=3
    it looks like it will do it.

    Anyone want to tell me their opinions of the Thorp?

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    The T-18/S-18 would be a good choice. I was building one in 68 when the National Guard put me on active duty. Something about pilots needed someplace. While I was gone, my basement flooded and trashed my project.
    JT designed it to go together fast and easy with no jigs. Building instructions were published in Sport Aviation. The T-18 Mutual Aid Society (you have their link in your post) was and is an effective resource. The T-18 was designed with a cockpit width of 38". It didn't take long for builders to widen that a few inches. The M.A.Soc. can help with that. The S-18 is mostly the same as a T-18. When JT died, Lou Sunderland took it over. The T-18 has a detachable one piece wing. The S-18 has an option for a folding wing.
    The T-18 has an excelent record. One bad spot was caused by stabilator flutter and resulted in a fatality in 68. November 1968, one plane's stabilator exploded in flight. I saw the pictures. He landed OK and it was blamed on flutter caused by accumulated slop in the linkage. Three months later, JT sent me 4 or 5 dwgs with changes to the stabilator and no problem since.
    I got a little stick time in the late 70's. Realy nice handling. Lands about 65. The two of us dressed out about 400-450. Full 29 gal fuel. Neck snapping t.o. It has differential ailerons and push rods.
    I still have my orrig dwgs (#457) about 199 sheets, some are 4 ft wide. Tried to sell them in june, no takers.

    Bob

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    steveinindy's Avatar
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    Quote Originally Posted by Mike Switzer View Post
    I have been working on designing my own plane, but I am beginning to realize that this is going to be a long process, & I want to be building now.
    LOL Tell me about it. Count yourself lucky....you can meet your needs with something off the shelf. I think the Thorps are neat little planes but have no first hand experience to report.

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    Mike Switzer's Avatar
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    I don't really care about the folding wing, but I do want the 2" wider cockpit. Some of the web sites say the S-18 has 100lb higher gross, but I'm not sure if that is true & I suppose it would depend on engine choice.

    I'm not real excited about riveted sheetmetal construction, what I have been working on is welded tube frame but the only thing that comes close to what I need that uses tube is the Smyth Sidewinder, and from what little I have found on it the Thorp handles better, and the Thorp has a much lower rate of stall/spin accidents.

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    Mike Switzer's Avatar
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    The one other design criteria I have is it has to be a lot faster than our club's 182 or Arrow, otherwise it doesn't make a whole lot of sense to spend time & money building.

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    steveinindy's Avatar
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    Smyth Sidewinder, and from what little I have found on it the Thorp handles better, and the Thorp has a much lower rate of stall/spin accidents.
    Where are you getting the stats from? And how many of those Sidewinders have been built? I have never even heard of it before If there's only a few of them, then you (as an engineer) know that have to be careful with drawing conclusions about rates of this or that.

    The one other design criteria I have is it has to be a lot faster than our club's 182 or Arrow
    I need higher speed, longer range and an ability to actually haul a full compliment of passengers and baggage. Hence why I am forced to go through the exercise that is designing my own aircraft.

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    Mike Switzer's Avatar
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    Quote Originally Posted by steveinindy View Post
    Where are you getting the stats from? And how many of those Sidewinders have been built? I have never even heard of it before If there's only a few of them, then you (as an engineer) know that have to be careful with drawing conclusions about rates of this or that.
    I'm still looking into it. I found a few webpages that claim 30% of the fleet has crashed due to stall/spin accidents. I'm not so sure I believe that, as so far the accident reports i have found (a handful worldwide) all seem to have had fuel issues, either ran it dry or had the fuel valve in the wrong position, most on takeoff, & failed to lower the nose when the engine quit. I'm not so sure that wouldn't happen in any aircraft with similar performance if you lost power & didn't lower the nose quick. There are some other references to it being "squirrely" but reading between the lines on those planes the fuselages may not have been welded up "square"

    The big issue for me would be cabin width, it uses the same canopy as the Thorp & Mustang 2 but the only page I found that listed a dimension said 36" & that wont work for me.

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    I've read the claimed 30 % loss rate on the Sidewinders as well, think it might have been on a Falco site

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    Mike Switzer's Avatar
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    Quote Originally Posted by David Darnell View Post
    I've read the claimed 30 % loss rate on the Sidewinders as well, think it might have been on a Falco site
    I think it may have been repeated a few places. I'm not sure it has the useful load I need, most places i have found say it is below 600lb, that wont work for me, but that may be with the original O-290

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    steveinindy's Avatar
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    Quote Originally Posted by David Darnell View Post
    I've read the claimed 30 % loss rate on the Sidewinders as well, think it might have been on a Falco site
    http://www.seqair.com/FlightTest/Kil...lYourself.html

    The Glasair III is a very-high-powered, high-wing-loading airplane. It was like jumping into a P-51 without proper training. Lose an engine, and you come down at 2600 fpm.
    Remind me again why I am purposefully going to plan for that and try to get a decent glide performance out of my design?

    According to Wikipedia, there were only like 40-some aircraft registered for the Sidewinder. There are 13 events listed in the NTSB records.
    NYC07LA241 Pilot apparently required CPR on scene but survived after a runway overrun following a hot landing. Honestly, given the fact that he survived most likely indicates that it was a medical problem that caused his cardiac arrest (since the survival rate for blunt traumatic arrest is pretty much zero).
    DEN04LA070 Forced landing after fuel contamination induced loss of power
    CHI02FA059 Base-to-final stall/spin. 2 dead
    LAX00LA238 Fuel exhaustion induced forced landing
    NYC00LA114 Partial loss of power for undetermined reasons
    FTW96LA301. Runway overrun
    FTW96LA257 Fuel exhaustion induced forced landing
    FTW96FA085 Spin stall during forced landing after loss of engine power due to fuel starvation. 1 dead
    BFO93LA160 Landed short of the runway
    CHI90DEE09 Runway excursion due to crosswindsATL88DMG04 Noseover
    DEN88DQA03 Spin/stall during attempted forced landing after prop separation 2 dead
    LAX85FA229 Spin/stall on final 2 dead

    So four of thirteen accidents were due to stall/spin= 30.7%
    Assuming 46 examples flying (from Wikipedia) that means 8.6% have been loss to this issue. If there are more that have been built, then the percentage is even lower.
    Last edited by steveinindy; 09-04-2011 at 10:57 PM.

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