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?

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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Originally Posted by Mike Switzer

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.

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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.

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.

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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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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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.

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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

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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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Originally Posted by steveinindy

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.

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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.

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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Originally Posted by David Darnell

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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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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Originally Posted by David Darnell

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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http://www.seqair.com/FlightTest/Kil...lYourself.html

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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.

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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.

Steve, many of the accidents I found were not in the US, I have no idea how many were built overseas. Without those numbers it is difficult to come to a meaningful conclusion, but I believe the stall/spin figure of 30% of the fleet is probably an exaggeration. If it is 30% of the total accidents, as your figures indicate, that is on par with several certified designs.

In case anyone else is interested, I had sent an email to Classic Sport Aircraft as I could not find the price on their website for the plans for the S-18, I just got an email back that they do not sell the plans by themselves, you have to buy the kit to get them. I guess the only plans built option for the Thorp is the T-18 & widen it yourself if so inclined.

Personally, I prefer to do things myself if I can save some money (unless the part requires special tools that I don't have already).

Let me do some digging. I have some friends at the AAIB and TSB of Canada as well as the German accident investigation board (BFU). Give me a few day to a week and I'll see what I can come up with. I have a serious disdain for numbers be repeated that can't be verified. LOL

Steve - looking at the FAA registration database, it appears there are currently 108 Sidewinders listed & 61 with valid registration - I don't know if the ones listed without any info never had AW certificates or what. After I got tired of working outside today I read all the NTSB reports that come up for "Sidewinder" & while there are some stall/spin accidents, unless I overlooked something, ALL of the accidents appear to be human error of some kind. Either Cowboy flying, stupid pilot tricks, or stupid mechanic tricks.

Yeah, it seems like the common problem was people either coming in too slow, too fast or not paying attention to their fuel. Toss in the (sadly) "standard" fuel system issues of homebuilts and you have your entire loss rate more or less explained.

A couple that stood out to me: (paraphrased from memory, I'm not going to try to find them again)

The fuel tank had been cleaned by a local radiator shop. Fine grit was found in the fuel screen. (if I remember correctly there was quite a few years between condition inspections on that one)

The wooden prop departed the aircraft. The prop hub bolts were installed without a backing plate & the holes & bolts showed signs of wear (before the bolts sheared)

Then there are the non-rated pilots, & the high speed passes into near vertical climbs.

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Originally Posted by Mike Switzer

the high speed passes into near vertical climbs.

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No, no....get it right....that's "phase IV flight testing". You know, the one where you have to determine the amount of force required to pull the wings off the plane like a butterfly in the hands of a sociopathic kid.