Thorp Air Command - T18.net

Hi all
I haven't seen much recent discussion on the list about alternative power-plants for the T18.
I have been giving it a little thought as I am yet to make the engine decision.

UL Power have what might be a viable alternative to the O290.
I have no personal experience with this engine and have only come across information on the web at http://www.ulpower.com/
The 130hp model UL350iS could possibly do the job of the O290 and being about 60 lb lighter than the O290 it might punch above it's weight so to speak.
Anyone willing to comment on
a) it's suitability and
b) the ease of installing a non lycoming motor.
Cheers
Stuart

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Stug

Stug,
There are quite a few power plants that offer comparable power to he lycomings. He problem is weight, surprisingly the lack thereof, the thorp was designed for a relatively heavy engine (the 0290), if you hang a featherweight engine on the nose you're going to have to find a chunk of lead somewhere to make the cg work out right.

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Lee Walton
Houston, TX
N51863,N118LW
KEFD

The need to add or shift some weight could be an opportunity rather than a problem.
Weight is easy to find and could potentially be made " useful" I had in mind a possible dual firewall mounted battery system but there would of course be other creature comforts that could add some pounds back in.
I guess the bottom line question would be can you come out ahead on total weight and with the cg OK?
If not then I guess the benefit is limited to the motor and any benefits that may be drawn from it alone.
Would there be any scope to move a lighter motor forward within the usual Thorp cowls and avoid the need to add weight?
Stuart

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Stug

It may be an interesting exercise, but I think you'll find that the distance you'll need to move the motor will create its own set of problems. 60 lbs is a lot to make up for with a pretty short arm. A lot of us run 0320/0290s with the battery on the fw anyhow. Off the top of my head I think you'll have prop clearance issues as you move the motor forward, which will warrant a longer gear, which will alter fact the over the nose clearance on the ground as well as the ground handling of the aircraft (longer gear = main wheels aft which opens another can of worms). I think you'll find the snowball affect starts to get a bit out of hand after a while.

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Lee Walton
Houston, TX
N51863,N118LW
KEFD

If you stick with the Lycoming "Family", I think you can make adjustments as to battery location, prop size/type and add whatever other "options" you want...(auto pilot, glass panel, etc) w/o having to make "major changes to the airframe and w/o major W & B mods (lead in the tail), but when you want to change the design called for power plant, then you are looking at a different engine mount (possibly). Fuel delivery changes, cowling modifications (if you love working in fiberglass then it won't be a problem !) Probably the biggest factor that Lee pointed out will be W & B issues. I think this discussion about powerplants was discussed about 2 years ago ? Check the NL's and Thorp List archieves.

Not sure how you would move a "lighter" motor foward in the Thorp cowl as it is mighty tight in there now to begin with the current power plants.

RB

For those who make it to OSH this year and can make it to the UL power stand I would be interested in any any feedback about their engines.
UL recently released a 6 cylinder range from 140hp up to 200hp and they may have one on display, the new motors are still lighter than an O290 and look to be more compact than the lycoming, so might fit within the existing cowl without reworking. I'd be keen to hear what the thoughts are.

Wow! Compact 6-cilinder, 6-cilinder engines are smooth, how much lighter is the 6 than the 0-290? I looked at the website and these are impressive. Honda and Continental Colaberated on a 200hp aviation engine, same configuration as the Lycombing, I did get to read the test on it and this was sometime back. It had liquid cooled cilinder heads and I guess it ran like a sewing machine, smooth as silk. Then I didnt hear anymore about it, it probably got tied up in a pile of paperwork and lidigation. I sure like the Idea of alternative powerplants, had I myself had more experiance with the Thorp, More flight hrs and experiance, I would have opted for an alternative. But at my regency of experiance I opted to use somthing tried and tested and all has worked out just fine. Who Knows, back in the dark corner of my Garage under a tarp someday I might have an alternative that I have bought or purchased, A fire breather simular the the beast that Cubes keeps in a cage for his Mach 2 cloud burner!! Dan

installed weight is claimed to be
100-110kg or 220-240lb

Hi Stug,

UL Power is interesting... the UL520is weighs about the same & is the same length as an O-235. Smooth 6 cylinder, pretty flat power curve, & 180 - 200 hp. Impressive. Full power fuel burn is about 15 gph, and if you get down around 100 hp it's about 7 gph. Hmmm...
Also, it is a pretty new engine, & I've heard there have been some problems, but factory support is reportedly good. Everything comes with the engine... add a fuel line and a few wires and you're good to go.

Still, it's hard to beat a good old Lycoming. You know exactly what you're getting, and the vast majority of all Thorps have been there already. Another possible important consideration is that it used to be that any deviation from the plans, or the tried & true, in Australia, was a considerable obstacle to certification, compared to the USA. I don't know if that's still the case.

If you move the engine forward you'll actually increase the prop ground clearance unless you're thinking about making it a nose-dragger, but will make it a little easier to "cut grass" when on the mains, You'd have to modify/lengthen the cowl... might mess up the looks of a beautiful airplane.

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

Agreed it's hard to beat the lycoming but I am curious to see if one of these newer generation engines would work.
If the 6 cylinder UL power engine can fit within the existing T18 cowling and with the prop ending up in about the same place as the lycoming then i would give it some real consideration. I most definitely don't want to mess with the looks or make a new cowl. For now it is an interesting idea while waiting for more information and experiences to become available.

Regulations in AUS were strict for many years but the current experimental building category now allows substantial variation from existing designs or even your own unique design. The aircraft still needs to be signed off by an Approved Person using a risk assessment system which provided a lot more flexibility than was previously the case. Stuart

It will probably fit, but as it has already been pointed out - you'll probably also have a weight problem (too little). That would be the main reason for extending the mount.

[quote="stug"]Agreed it's hard to beat the lycoming but I am curious to see if one of these newer generation engines would work.
If the 6 cylinder UL power engine can fit within the existing T18 cowling and with the prop ending up in about the same place as the lycoming then i would give it some real consideration. I most definitely don't want to mess with the looks or make a new cowl. For now it is an interesting idea while waiting for more information and experiences to become available.

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

If you get the UL520i then its only 6 pounds difference, which I'm sure you could make up with an extra battery or some thing of the sort if weight and balance is an issue, then the only thing we would have to worry about would be if there is enough room under the cowls, as well as other things like an engine mount and correct propeller choice. and then we get the same power as a IO 360 at twenty pounds less!

we just need someone to do it so I can have an other option when I get to the point of getting my engine, I am still stuck on the proven Lycoming, tossed around in my head about a jabiru 3300.... but this ul520i is attractive.

I don

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http://www.dixiefriedfabrication.com/

Checkout Beltedairpower.com. Jess Myers alternative engine package has a zero failure rate after all the years he has been in business. That is a pretty good record considering his package is automotive............Dan