mustang II vs s-18 thorpe

just curious both these planes are similar but the take off and landing runs are at opposite ends of the spectrum ? is it the airfoils or just the way that the designers listed or tested the planes .

Keefer,

I don't know where you got your numbers, but the two planes are almost idenitcal. The T18 and the MMII have the same fuse width. The S18 is a couple inches wider and five inches longer. Both designers worked together and apparently shared ideas. I've seen Bernie Fried wheel land his award winning Thorp T18 in 1000 feet.

The biggest difference I know of is in the wings. The MMII has a tapered wing, which is much harder to construct, and the THORP has a Hershey Bar. Everything on the Thorp wings is laid out to use four foot wide sheets of Aluminum. (JT wrote an article on the Sports Aviation Archive on EAA.org like: Birds have tapered wings) The Horizonital Stabilator (like on the Raptor) is unique.

The Folding wings are almost identical. I don't know who copied. But, it is the best system ever designed for one person.

The THORP T18 is usually about 100lbs lighter than an RV7, thus the better performance at half the price. A light Thorp weighs 850lbs. One was built at 701lbs, but it was pretty Spartan. Canvas seats, 1/2 Carbon fiber panel, .025 skins, etc.

As you can see I'm a little perjudice. John Thorp was ahead of his time. Designed the first Homebuilt Aluminum Airplane. Came up with "Matched Hole Construction". All flying Stabilator and a great, timeless Airplane. No jigs, everything is laid out to fit standard size supplies. Wings and controls are removeable for transport. Then you have Lu Sunderland's folding wing!! Still the best after forty years. Classic Sport Aviation has the S18 kits. The T18 plans can still be purchased from Richard Eklund for "plans built". Richard has John Thorps house and shop where he constructs parts on JT's original equipment.

Thanks,
N2t18s

I spoke to a guy who'd built a Mustang II. At least I think that's what he said it was. He said it scared him. I don't think because anything was awful about it, just that things happened pretty fast when flying it and by the time he finished it, he was old enough to be slowing down. Kind of sad, really.

The Mustang wing also has a laminar flow wing, which is supposed to be more difficult to build, and I hear this has some meeting performance specs with those high cruise speeds mentioned, while others are falling somewhat short of what they were expecting, due to not getting this aspect right.

I like the fact I can use smaller engines on the Thorp if one wants to go this route, and JT’s reputation as an aero engineer is legendary, so I feel comfortable with his design. How do others like the Thorp plans? I’ve started researching Thorp’s T-18’again, and it’s difficult to know what I’m getting into just yet. I prefer not to build as a kit, but materials mostly. I understand the plans are $300.00 and are quite comprehensive. I was told there is also a supplemental part for an extra $50.00. Not sure if this is needed or not. Then there was shipping, so I’m guess I’m looking at close to $400.00 for plans. I talked to the guy at Eckland Engineering that says his is the T-18 plans which don’t cover the folding wing, and not sure what else it doesn’t include, so I guess there would be even more additional supplements to buy, I dunno.

IIRC, the Thorp S-18 plans that offer the folding wing, wider cockpit, longer fuselage and also supposed to be an improved wing airfoil that lowers stall without affecting cruise and top end, but their plans have to be purchased with a kit. What are most building these days?

Does anybody have some used plans for sale? I would like to look things over to see if it is doable, before I took the nearly $400.00 plunge on these plans.

I’ve notice virtually every site I’ve looked at doesn’t mention take off or landing specs on the Thorp; just know it takes up quite a bit of runway. Not sure if the Thorp can actually out perform the RV-7 or not. On Van’s site the RV-7 lists 199 mph at gross weight for their cruise on 180 HP. Van’s forum seems to have many confirming these numbers. What few numbers I seen others share for their Thorps seem to be around 180 mph for the 180 HP, but again, haven't heard from that many Thorp builders. Not much data is given with altitude, temp, etc for me to really know and make a comparison. It seems the Thorp has the potential to make for a faster plane due to generally being 100 lbs lighter, and the wingspan is quite shorter as well, but haven’t read from anybody cruising around 200 mph with the 180 HP engine. Van’s aircraft certainly have way shorter take offs and landings. But gosh, their prices have been through the roof for some time now since their kits have gotten so comprehensive, and is why I think building a Thorp with materials and not a kit form is probably best for me. You’ll have a similar aircraft for about half in it of what the RV’s have in theirs.

T18 plans are now perfect, but a little overwhelming at first. The $50 supplement is a basic instruction manual. There are about 150 Newsletters available detailing construction and the Yahoothorplist.

Every nut, bushing, bracket, etc has a drawing. (JT had a drawing of a wingnut) The original T18 was totally plans built. Now, Richard Ecklund sells many of the hard to build parts and Classic Sport sells the complete S18 kits. Some of the original T18 builders did not build the wing perfect. So, there were some T18's that had a very abrupt stall with no warning. Now most T18's have Stall Strips on the leading edge of the wing to give a buffet warning.

Lu Sunderland came up with the S18, the more forgiving wing profile and the folding wing.. Many of the T18's have the Sunderland wing profile and/or the folding wing mechanism. I've added Pics of prints and a Bellcrank at:

http://www.angelfire.com/pro2/gsa/tools/

Bob