Help a newbie get his head around STOL engine options...

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Timstertimster

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Apr 18, 2014
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Hi everyone. Been lurking a while...

Peat this point I decided I will attempt to build a STOL from a commercial kit. Something like a Highlander or Zenith or similar. I'm most interested in short takeoffs and landings... The ability to land on a postage stamp is terribly exciting to me. As long as I can take off from said postage stamp, that is :)

Now I'm trying to understand engines better. I only have bookworm knowledge so far, and would like to get better at evaluating engine options.

What kinds of tried and true options are out there? I understand it's not enough info so I will attempt to narrow it down, even through I'm not 100% sure why.

Air cooled
direct drive
100 hp or thereabouts
lightweight
4 stroke
TBO should not be too low
Straightforward to understand engineering. I don't want to have to go to a mechanic for everything
cheap

Rotax is all well and good, but ouch my wallet...
Jabiru is apparently rather heavy
ULpower also interesting, but a bit pricey for me.
Honda looks interesting but also not super heap, or is it? The auto engines are.
Lots of old postings on this forum with links to defunct websites...

I would be thrilled to hear some people here point to solid engines that can be used for the purpose without breaking the bank. And if it has to be a rotax 582 I guess I'll have to get comfortable dealing with gearboxes I suppose...

Thanksmfor any pointers.
 

dcstrng

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As a general rule you’ll want to spin a fairly long blade for low-speed/STOL operations and with your no-PSRU requirement you’ll have to rule out the Honda/Rotax unless you’re thinking of some variation I’m not familiar with. On a budget, you could come up with a mid-to-high time O-200 or O-235 that would more than fill the bill (check Barnstormers, Ebay or even Craig’s List). Don’t have a lot of familiarity with the Highlander except for its sterling reputation, but the CH750 could take either engine, and with careful (no-frills) the O-200s have been used in CH701s.

I still harbor a fantasy of finishing a Spartan CH701 before I write the big check, but lately have been thinking of a super-light, austere bird similar to the originals but powered by a Rotax 670 – but one project at a time.
 

cheapracer

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Jabiru is apparently rather heavy
Apparently you would be wrong. Go to their website would be the easiest way to establish what they weight but 60kgs and 80kgs for the 4 and 6 respectively I believe doesn't sound like a lot to me. Some people have great runs out of Jabs and some enter a world of pain, best investigate thoroughly.
 

Max Torque

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Timstertimster,

From the list you posted, you should take a hard look at the Corvair engine (done according to the flycorvair manual). They are really nice engines. Especially, the 3.0 liter (see http://www.flycorvair.net and http://www.flycorvair.com ). There are hundreds of Corvairs flying. By building up the engine yourself, you will know the engine inside & out. The initial cost is fairly low, but the long term operating and rebuild cost is super and parts are available from the auto stores.
 

dcstrng

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Timstertimster,

you should take a hard look at the Corvair engine...There are hundreds of Corvairs flying. By building up the engine yourself, you will know the engine inside & out...
I agree the Corvair is a viable alternative (I’m building one for my project), but I think the builder who uses one outside of the CH750/CH650/KR world where they are well known will be uncommon. For some reason the KR and Zenith fliers are pretty comfortable with them and they don’t even raise eyebrows, but elsewhere they are often view as some sort of aviation alchemy…

The Corvair is not the lightest engine out there, but if the bird is configured to account for the extra 25-60# they have worked quite well. I disagree with the big-names in the Corvair world in trying to get 120-140hp out of them and for my configuration plan to detune (via smaller carb) so that it is more in the Bernie Piertenpol category – about 85hp – but that’s just me. Mine is actually a 100-110hp configuration with Integrated front bearing and the usual bells and whistles, but…
 

addaon

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San Jose, CA
I've spent a lot of time looking at the CH 701, started building one, flown several, and talked to quite a few owners. Everyone with a Rotax 912 is happy with their engine. It's more complex, more expensive, etc... but it works incredibly well in that particular application. As someone who generally dislikes the complexity of the Rotax, I think that anything else in the 100 hp STOL range would be a mistake. (At 80 hp and west of the Mississippi, I'd seriously consider the HKS 700T, but that makes the Rotax price seem good.)
 

addaon

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The O-200 / O-235 are a bit heavy for the CH 701, although workable; they're a much better fit for the CH 750 (as is, of course, the IO-233).
 

Vipor_GG

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Cayce, SC / USA
Also remember that take off and climb out are not the same. Getting off the ground is useless if you can't climb above the 50' trees at the end of the field.

[video=youtube_share;vpxDqe5gbcs]http://youtu.be/vpxDqe5gbcs[/video]
 

Timstertimster

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I love the d motor! So clean and compact, but liquid cooled.... I worry about flying a liquid cooled engine in northern Alaska. Not interested in getting stuck at Deadhorse Airport ;)

Poor is that worry unfounded?

Price looks good for the 4-cylinder version. I hope 95hp is enough to kick the plane into the air in a jiffy? I'm wondering if this engine is strong enough for a highlander. I could see it on an egull...

Choices, choices... Sigh.
 

Victor Bravo

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KWHP, Los Angeles CA, USA
STOL also leads directly into back country flying, and back country flying demands reliability.

The Zenair CH-750, using an O-200 or lightened O-320 will have exceptional performance, and more importantly have an exceptionally reliable engine. That may not matter at a local farm strip, but out in the wilderness three days' travel from any civilization it will matter a lot.

Go and talk to experienced, real-world STOL back country pilots about engine reliability before you make any decisions.Ask how many Super Cubs are operating out in western Alaska using the Rotax.
 

Timstertimster

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Apr 18, 2014
Messages
59
Location
Bay Area CA
Go and talk to experienced, real-world STOL back country pilots about engine reliability before you make any decisions.Ask how many Super Cubs are operating out in western Alaska using the Rotax.
Thats why I hang out here at HBA... To hear what experienced folks have to say about engines.

I think it's imperative to know every screw and washer on your plane if you're 500 miles away from the next gas station. Is it feasible to have an engine you know you can fix yourself with just the emergency tools you bring along? With cars, I've had a situation once... fixed cooling system leaks with duct tape and got my '67 mustang out of death valley into Vegas (the one genuine adventure of my life so far, where I was truly worried about making it)...

After that experience, I'd like to at least know what I'm doing before getting myself into trouble again :speechles
 

dcstrng

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I think it's imperative to know every screw and washer on your plane if you're 500 miles away from the next gas station. Is it feasible to have an engine you know you can fix yourself with just the emergency tools you bring along...
The beauty of homebuilding is that done properly (i.e. minimal “professional” assistance) you will probably know your bird better than anyone… Build it yourself, build it simple, keep it reliable, and keep it light…

If I were pursuing the backcountry STOL notion from scratch (my CH701 is on hold while I complete my current project), I’d be very tempted to go CH750 or Bearhawk (depending on your pilot-skills/shop-skills and proclivities) and power it with a mid-time O200… There are many other options, but these two have been soldiering on without drama for some time -- almost no surprises – of course if money is no object – then one of the Carbon Cubs would be my fantasy bird… ;)
 
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