Thorp Air Command - T18.net

Hi All, I had the IO 320 or 360(preferred) in mind for my S18(see projects board for introduction. I then came across the UL Power range of engines. Full spec's can be found at this link - http://ulpower.com/en/engines/ul520/ul520i

I short, this is a 6 cylinder engine delivering up to 180 hp and runs on minimum 95 oct mogas, with a ready to fly weight of 238 lb, and X, Y, Z dimensions of 28.4",28,97", 18.6". From what I
can see, this equates ro a saving of approximately 60 lb's over a 360. Dimensions are also more compact than a 360.

Would appreciate your opinion on:

1) the suitability of the UL520i as an alternative powerplant (apart from 4 vs 6 cylinders, seem to be of similar dimensions and design)?

2) opinions on the UL 520 engine peformance and reliability.

Regards
Ruben

This is the first I've heard of this power plant . Seems to be in limited production for only certain airframes . Sounds like they can develop a PP for a particular airframe , but not sure how the cost works out for that R & D ? As this company is based out of Belgium it seems more suited for the EU market as there is only one US distributor which would seem to make is difficult to obtain parts ? Looking at the cost of the 130hp version it is about the same as I paid for a zero time 0-360 . Then you have the problem of mounting the PP to the existing Thorp engine mount and containing it in the current cowl configuration . This would mean more time , $$$ and modifications to make an unproven PP work in an airframe that has used the proven Lycoming PP since day one . I guess if you have a lot of spare time , $$$ and patience you might be able to make the combination work ? It's an experimental aircraft and you can pretty much do what you want in the US . Not sure abroad ? Someone once said if you put enough horsepower behind a turd it will fly !

RB
BaBaLu

5.2Liters = 317 Cubic Inches, very close to a Lycoming 0-320.
Claimed power @2700 RPM = 165 HP, very close to a Lycoming 0-320.
180 HP is @ 3200 rpm, Unusual for a standard aircraft propeller, but can be used with a wood/composite prop if specified when ordering.
I like the idea of a 6 cylinder engine, they run smoother than a 4.
UL 4 cylinder engines seem to be doing well, but the 6 is a new product.
Time will tell.
PS, as a light weight engine, you might need to pay close attention to weight & balance. Mother Nature does not like tail heavy T-18s.

_________________
Scott Emery
EAA Chapter 326
T-18 N18TE

I have followed this Company in their progression of their product, and they are very Impressive. Their engine is a work of art and it is physically smaller than the Lyc and lighter, but it is powerful. It is a single control engine, no mixture no nothing except a throttle and that is about it, start it up,throttle in to go fast ,throttle out to go slow, it was designed by a group of Race folks and was designed for longevity and low maintenance. They do have a history that goes back into the 70s I believe and an incredibly good track record which is to be expected with the technology we have today. Check out you tube there are some point made on this power plant that are nothing shy of groundbreaking. I would hope that someone would utilize one of these rigs so we all could know what they are about first hand, I believe there is one on KVIS airport but havent seen it yet. (they are Pricey as Rich has pointed out) Dan

One of the "issues" with the advertising of these engines has been the horsepower figures at 3200 rpm. That is an inefficient rpm for most propellers with diameters that are commonly used with our airplanes. The fact that it's made out of wood or metal isn't the issue. It's the fact that propeller tip speed approaches or exceeds the speed of sound, and efficiency goes to hell, making the advertised horsepower at that speed irrelevant for the application. They are nice looking engines.

_________________
John Evens
Arvada, Colorado
T-18 N71JE (sold)
Kitfox 7 SS N27JE

There has been over the years different engines show up on the light airplane market and none have delivered what was advertised , I wish them luck with the development of their engines, I'm still of the opinion that if it does'nt say Lycoming on the valve cover it's not an airplane engine. There is an exception when it comes to round ones.

Here is a link to a tip speed calculator:
http://www.warpdriveprops.com/propspd2.html
I ran a 68" diameter prop (stock T-18) @ 3200 RPM and it came up with .84 Mach, which is darned good.
I was referring to custom propellers being able to run at 3200 RPM plus some overspeed factor, like 10%, say, 3520 RPM to be safe when you let the nose drop and the speed starts to build up!
I have easily seen 3000 RPM with my O-290 and Hendrickson 68x68 prop when arriving at a destination, descending from 10,000' full throttle. (How cum it's so LOUD in here ala suddin?)

For the curious; 68" prop @ 2700 RPM tip speed is .711 Mach

_________________
Scott Emery
EAA Chapter 326
T-18 N18TE

Thanks for that Scott... my comments were incomplete and inaccurate. Propeller design has a lot to do with the performance as speed increases, in other ways besides just diameter of course. I was repeating comments that I've heard so many times over the years that I just didn't bother to check or think about it much. It would be interesting to see how some of the popular propeller types used on T-18s actually perform at those higher speeds, like 3200 rpm. As you noted, they definitely get noisier. The little Formula 1 racers with the O-200's run way over 3000 rpm, and man they scream. I wonder what kind of Mach numbers they are at.

_________________
John Evens
Arvada, Colorado
T-18 N71JE (sold)
Kitfox 7 SS N27JE

it's going to hard to find a jug at dunmovin Ca. airport on a Saturday for the UL.

My question is what does "loses efficiency close to the seed of sound" mean? .84, .92, what's the magic #?

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http://www.dixiefriedfabrication.com/

Hi All, thanks for all the responses. This is mostly new to me, and clearly have a lot to comprehend.

Please keep the comments / discussions on the topic coming.

I will also contact the supplier to find out there opinion on the propeller.

Regards
RL

Wait a minute...I've been to Dunmovin CA. Airport !! If you want nothing to do go there !

RB
BaBaLu

RL;
ULpower should welcome your call. Be sure to have your S-18 specifications ready. Things like take off speed, stall speed, climb, cruise and max predicted speed and propeller diameter would be useful.
They might have a propeller in mind, or just provide some parameters that you would forward to a prop maker.
I don't think the Sensenich and Wirlwind carbon fiber ground adjustable pitch propellers are approved for 3200 RPM, but Craig Catto and the other custom wood/composite prop makers will build to your specs.
I had a custom 2 blade left hand turning prop made (Catto) for my RV-8 when it was powered by a turbocharged Mazda Rotary.
I was totally satisfied with that prop. Craig took the time to discuss my specs and tell me how he could re-pitch if required, but it was right the first try.
The other well established custom prop makers will probably do the same for you.

_________________
Scott Emery
EAA Chapter 326
T-18 N18TE

Cubes and I talked to the UL folks at OSH. Very interesting! Nice looking engine, but mounting/motor mount may present some problems in the Thorp.

_________________
Bob Highley
N711SH
SN 835
KLAL

That's funny Bob. I was typing a response the same time as you.
I came away quite impressed. Excellent engineering on these motors. They have thought of a lot of things most airplane engine guys have not. Such as altitude compensation.
However, they added a seven inch engine mount extension to make the W&B work. That would be hard to fit in a Thorp. I believe he said the firewall forward was in the neighborhood of 43 inches. Ours are typically about 33. That's a great big mountain to climb. So is the cost.
Cubes

Thanks All, will stick to the proven product, much easier. Still learned a lot from the disucssions though...

Cheers
Ruben