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New engine for Sonex.

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tdpilot

Member
Joined
Feb 20, 2011
Messages
15
I am adapting a new engine for my Sonex. It is the most thoroughly engineered engine ever built in this world, puts out about 125 hp, is still being produced, is simple, water cooled, and available everywhere in the world. I am making absolutely NO changes to the engine at all, just installing a long prop adapter between its V-4 cylinders. The prop will be a 4-blade very coarse pitch wood prop. I anticipate over 200 mph when I get it all finished, and shorter takeoff greater climb rate than with any current engine. "how's that possible??" you ask.
Well, the engine STILL HAS its 4-speed WITH REVERSE transmission attached. Want REALLY short landings? Reverse. That's really getting carried away, and not really possible. You would have to brake the prop to a stop before reversing. But it could be done. When I am ready for takeoff, I use first gear. Climb on 2nd-3rd, cruise on 4th. Shift easily in the air just as original.
The engine uses regular ethanol-added car gas, just stop in at your local gas station on the way to the airport. Want oil filters, OIL? Available at Walmart. Want parts? Many thousands of dealers worldwide, and your local junkyard. Lots of them there. That's where I got mine. For $700. Low mileage, no damage at all.
Weight, firewall forward, is almost exactly the same as a Continental C-85 firewall forward.
What is this "miracle"? Just the most common most reliable engine in the world, almost. An engine out of a Honda CX-1600 motorcycle., Just under the flat-six Goldwing bike. Has been built for over 20 years, and is still in production. Stay tuned. The prop adapter shaft dynafocal belt-driven right off the normal power-out shaft is already installed. I'm waiting on time to get the rest of it done. Do have a few other projects, like getting Hurricane Storm Surge Barriers built for our local bay so that I don't lose my home in another Katrina, does take some priority. This is an experimental project, obviously, but I see no reason it won't work. I emphasize that I have made NO changes to the engine, at all. Just installing the prop adapter shaft and building a suitable motor mount. Cooling radiators, exhaust piping, etc. Lots of detail, time-consuming stuff.
If you are interested, I will set up an email update site, [email protected].
I plan on eventually producing the prop adapters. They aren't overly simple to get to work right. It is right now all aluminum welded construction, and the two support bearings are about 20" apart. Not many problems with weak shaft support. I would probably eventually make them from casting. The support is rather labor-intensive and requires expert aluminum welding right now.
Also, anyone interested in a virtually new Volkswagon engine with all the adapters, and baffling, ready to install in your bird? I took it out of mine after purchasing the plane from a dealer. I was only interested in the plane for my engine experimentations. It did have a minor idle-power wood-prop strike, broke one blade, on the initial test flight. No damage at all to the engine that I can see, but no guarantee because of its history. It had just been thoroughly rebuilt to factory specs by a local VW engine rebuilder shop. Around a $7-8,000 engine. $4,000.
 
NO SIR! Aside from a new induction manifold (needed to clear the prop shaft adapter) and new exhaust pipes, I have made NO changes to the engine AT ALL. I wanted to preserve the integrity of the original engine. I am not the hundreds of engineers who have developed this engine over the years, and I am not about to be so arrogant as to discredit their work by doing something different. I will caution everyone that this is still a work in progress. I won't be able to say anything more until I actually have it in the plane and flying for at least 100 hours. I just wanted to let everyone know there is someone who is working on an engine setup that I personally think will establish new standards in our engines, new availability, and supremely lower costs. Will it work? I think so. I would add that I have been around aviation, and experimentals, for over 60 years now. I am a 10,000 hour+ CFII, and 55 years as an A&P. I currently own five planes, including the Sonex that this engine will be going into. As soon as I can get the time to work on it again! Trying to get our local Hurricane Storm Surge Barriers built, so my home doesn't disappear in the next Katrina, (which my entire neighborhood did in that storm) does take some precedence.
 
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you might have missed the point of Danman's post.
The thing that keeps killing "alternate" engines with re-drive, or front-drive VW's with hard reduction drive, or heavy propellers, is torsional vibration. Or even Rotec's, possibly. Even many "factory" engines like Lycoming or Continental can break crankshafts or at least ruin bearings and detune (fail) the pendulum counterweights if the wrong prop, or wrong prop length, or wrong RPM with a given prop is used.

That said, I think your idea has a lot more merit than many & is probably worth the experiment.
You apparently have the experience to be the test pilot.
As i think you describe, cog belts are widely used as a somewhat soft connection to mitigate torsional vibration issues. (I don't know what a "dynafocal belt-driven" is? Also, there does not seem to be a CR -1600 motorcycle. Can you post a direct link, please? (I am aware of the 1800cc Honda V-4's)

Considering MC engines; Triumph makes a 2450cc dry sump inline triple with gobs of low end torque. :^)

It would seem that retaining the gearbox could complicate the unknowns for torsional vibration; though the dampers in the clutch may or may not improve things.

Looking forward to flying reports.
smt
 
Sorry for the confusion, Aviacs, I should have done a better job of my "editing." The engine is out of a Honda ST-1300, not 1600. It is the V-4. And your comments about torsional stress are exactly why I am going to the Dynafocal belt for a final drive. That is the belt that drag racers use to connect their blowers to the engine. They are wide, toothed belts that offer NO slippage, but do provide a great deal of torsional vibration isolation, particularly when used with an idler pully, which I intend to use, ----but may not, as not using one will save weight. As to the engine-to-prop connection, there are two clutches in the ST-1300 transmission, plus gears, all of which will serve the vital function, (in my opinion) of each absorbing their portion of the torsional forces generated by any piston engine. I feel that is so important, and why I am firmly against the Rotax and Jabaru engines. Those forward-mounted gearboxes with, IN MY OPINION, very short actual prop shaft support, and additional torsional loads and gyroscopic forces generated by the height of the gearbox itself, and rapid pitch changes----just plain scare me. I will fully admit that their experiences do negate my concerns, I guess. That I know of, there haven't been problems with the forces that scare me. That's why I designed my prop shaft adapter to have a separation between bearings of 20". There isn't anything magical about that number, it just happens to be the distance that my prop shaft adapter required. The adapter mounts on both the front and rear mount of the engine, and the bearings are both outside of the mounts. With the dynafocal belt, and the two clutches in the transmission, plus the multiple gears in the transmission, I anticipate the smoothest prop (by vibrations standards), ever. There should be NO torsional vibration at all reaching my prop shaft. Just pure torque.

Re your Triumph suggestion. Yep, that is a great engine. Ever tried to find one???? :>))) The Honda overcomes virtually all engines simply because of its availability, and L-O-N-G history of so many Honda engineers trying to keep their jobs! There has never been a more thoroughly engineered engine, and it is still in production. As you well know, there is no more thorough, more punishing test program as just plain daily use. The Hondas have been brutalized for a very long time, and they have been the recipients of all that "testing".
My retention of the transmission???? Stay tuned for the actual results. Right now I have seen only one engine that did this, and it was on an ultralight that had about a SIX-FOOT chain driving its prop! And since it was so speed-range-limited, I don't think anyone would see the real justification for the transmission retention on the application, except it made the conversion much simpler. It did work, and worked well. Separating the transmission from my engine? I'm not sure it could even be done. Plus I am so intrigued with my theory about using it, in combination with a very coarse-pitched 4-blade WOOD prop------Frankly, I can't wait to actually see if it is all going to work. If it does, I suspect it will completely revolutionize our choice of engines. I mean, an engine with these capabliities, this engineering level, this AVAILABILITY, turning a hand-made wooden prop. (cost of prop--just the wood) with a firewall-forward cost of maybe $1,000 from virtually any junkyard, with no miles and no damage????
 
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Another thing about my engine. Virtually all the AIRCRAFT engines have to turn at around 2,000-3,000 rpm, in order to have reasonable prop tip speeds. Very few piston engines produce any power at those RPM's. The Rotax/Jabaru engines solve that problem partially with gearing, but----they still only produce power, real power, at one prop speed. I think I will be able to turn the Honda at its rated HP speeds, around 5500, 6500 when I want to, with no problems of prop tip speed simply because of the transmission delivering that power to the prop, at a prop RPM that the prop is happy with. To the best of my knowledge, this has never been done before. In a plane with a very large speed range, such as the Sonex, this should be an interesting exercise. ------Then we put the engine to work with a ducted fan-------------
 
Kind of funny you talk of putting a motorcycle engine in an airplane because my motorcycle has an airplane engine. BMW with a Rotax engine :)
 
WOW,, Talk about Reverse-Engineering! Is that experimental, or a new BMW product? If it is a product, it is a huge advance for Rotax, because that is a whole lot better experimental database platform than aircraft ever will be. ------ Just as a curiosity thing, a good buddy of mine, Ron Shettler in Canada was responsible for the very first commercial Rotax utilization in an ultralight, and the father of the Rotax movement then. Ron really wasn't into man-carrying planes, he was much more well known as the developer of the Quadra chainsaw engines for giant R/C model planes. (I was the founder of the IMAA, for those of you familiar with R/C planes) That is how I met him, I was also heavily into the introduction of giant models. It was his introduction of those engines that made giant models initially possible. When I visited him one day up there, he had the very first 4-cyl Rotax 912 ever in the Americas sitting in his test stand, ready to mount on a plane. As far as I know, he never did accomplish that. I don't know what happened to that first engine. He died shortly after that.
 
I have flown many hours behind high RPM engines (mostly Rotax) and they have advantages. That said, isn't the practice when converting an engine to aviation use is to de-rate it? The 117 hp (87 kW) @ 8,000 rpm doesn't sound like there is room to de-rate it. The torque is 117 N⋅m (86 lb⋅ft) @ 6,500 rpm on the wiki and sounds awfully low. I am by no means an expert but the marketing says you get more torque from a VW Type 1 2180cc;
HP-Torque_graph.jpg
 
I have flown many hours behind high RPM engines (mostly Rotax) and they have advantages. That said, isn't the practice when converting an engine to aviation use is to de-rate it? The 117 hp (87 kW) @ 8,000 rpm doesn't sound like there is room to de-rate it. The torque is 117 N⋅m (86 lb⋅ft) @ 6,500 rpm on the wiki and sounds awfully low. I am by no means an expert but the marketing says you get more torque from a VW Type 1 2180cc;
HP-Torque_graph.jpg
The gearing at say 3.2 would produce a prop rpm of 2500 and that multiplies the torque to 275!
 
WOW,, Talk about Reverse-Engineering! Is that experimental, or a new BMW product? If it is a product, it is a huge advance for Rotax, because that is a whole lot better experimental database platform than aircraft ever will be.

It's the motorcycle's stock engine. It's a 798 cc twin Rotax. I didn't take an engine out of an airplane and put it in my bike, I just said it's an airplane engine because Rotax is more known for their aircraft engines than their powersport engines.
 
The gearing at say 3.2 would produce a prop rpm of 2500 and that multiplies the torque to 275!
Well, when you guys get this engine flying I would love to take a ride! Be sure to keep us all up to date. At 275 ft-lb you are easily replacing much, much more expensive engines and for a whole lot less fuel consumption and weight.
 
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It's the motorcycle's stock engine. It's a 798 cc twin Rotax. I didn't take an engine out of an airplane and put it in my bike, I just said it's an airplane engine because Rotax is more known for their aircraft engines than their power sport engines.
Take a look at what Kevin is flying with ~$900 ACE PSRU 2.31:1 ratio. Core 800 CC engine is a ROTAX ATV engine clone. If I tried to replace my 2276 CC VW with one I would switch it to a Carburetor for simplicity with Carb heat. The Ignition is controlled by a independent ECU from the fuel injection. Would seriously consider working up a fixed secondary ignition and run a common spark plug with two. MSD 8210 Coil combiners.

If anyone wants pioneer the effort for a Sonerai you are the mechanic in charge just like Kevin Armstrong on his trike. Mounts, cowl, Firewall forward plumbing all way more complicated than a direct drive aircooled VW but a 65hp twin turning a larger prop would make a great LSA tractor engine. You can use a legit ROTAX or a clone your choice with the ACE drive. I have no interest in ACE but John looks like a reliable enterprise with history with sound QC in place to deliver a quality option.

My conservative guesstimate is 65kg or less flying weight including engine mount exhaust and coolant but before Prop is added.

REF
Kevin the original ACE Drive designer/Twin conversion Pioneer in action

https://www.aceaviation.co.uk/redriveshttps://www.gk-engine.com/engine/8500ccengine/Kevin is using the 800cc 1000CC is also available...
https://www.summitracing.com/parts/msd-8210
 
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TD, I don't think your ST1300 setup will work as envisioned. It's only going to put out about 75 HP at 5500 rpm. Running it at higher power setting would probably be an invitation to engine failure. Those max power settings in motorcycle use are peak events of very short duration. A racing bike might be able to do it for an hour, but then is probably looking at a complete tear down before the next race. Bigger issue is trying to use the engine and shifting the transmission to control the power curve. Nothing inherently wrong with using the trans for the rpm step-down and drive bearing if its final drive can withstand the axial loads and does not exhibit harmonics. But you'd need to pick a gear that gives you the right prop tip speed with the engine running ~5,500. For prop engine setups, the transmission is the adjustable propeller that allows a fairly constant engine rpm that can bite the air at maximum efficiency as aircraft speed changes. Your proposed setup involving shifting the transmission would have prop speeds all over the spectrum and that's neither desirable nor efficient and would be making the prop go through a lot of variable stress events. Using a 4-blade wooden prop for 75 HP is not going to be efficient compared to a two blade, IMHO. There is a lot to be said for the KISS method in homebuilts. You'd probably be better off rebuilding your prop-strike engine, a direct drive corvair or even a Jabi. There are some new Suzuki engines being adapted to aircraft use that look pretty good, and they've already done the engineering.
 
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TD, I don't think your ST1300 setup will work as envisioned. It's only going to put out about 75 HP at 5500 rpm. Running it at higher power setting would probably be an invitation to engine failure. Those max power settings in motorcycle use are peak events of very short duration. A racing bike might be able to do it for an hour, but then is probably looking at a complete tear down before the next race. Bigger issue is trying to use the engine and shifting the transmission to control the power curve. Nothing inherently wrong with using the trans for the rpm step-down and drive bearing if its final drive can withstand the axial loads and does not exhibit harmonics. But you'd need to pick a gear that gives you the right prop tip speed with the engine running ~5,500. For prop engine setups, the transmission is the adjustable propeller that allows a fairly constant engine rpm that can bite the air at maximum efficiency as aircraft speed changes. Your proposed setup involving shifting the transmission would have prop speeds all over the spectrum and that's neither desirable nor efficient and would be making the prop go through a lot of variable stress events. Using a 4-blade wooden prop for 75 HP is not going to be efficient compared to a two blade, IMHO. There is a lot to be said for the KISS method in homebuilts. You'd probably be better off rebuilding your prop-strike engine, a direct drive corvair or even a Jabi. There are some new Suzuki engines being adapted to aircraft use that look pretty good, and they've already done the engineering.

We'll see. The only thing that can really happen is that it won't work as I envision. But, I have been around aircraft for about 55 years now, as an A&P, and this is something that I am basically fiddling with, and making one of the most completely engineered engine SIMPLY into something that can be used in aircraft, -------Especially one that can be eventually used by everyone, with only a rather simple bolt-on adapter, that can be built up by anyone, not necessarily a machinist expert, for less than $1,000, -----------
 
Take a look at what Kevin is flying with ~$900 ACE PSRU 2.31:1 ratio. Core 800 CC engine is a ROTAX ATV engine clone. If I tried to replace my 2276 CC VW with one I would switch it to a Carburetor for simplicity with Carb heat. The Ignition is controlled by a independent ECU from the fuel injection. Would seriously consider working up a fixed secondary ignition and run a common spark plug with two. MSD 8210 Coil combiners.

If anyone wants pioneer the effort for a Sonerai you are the mechanic in charge just like Kevin Armstrong on his trike. Mounts, cowl, Firewall forward plumbing all way more complicated than a direct drive aircooled VW but a 65hp twin turning a larger prop would make a great LSA tractor engine. You can use a legit ROTAX or a clone your choice with the ACE drive. I have no interest in ACE but John looks like a reliable enterprise with history with sound QC in place to deliver a quality option.

My conservative guesstimate is 65kg or less flying weight including engine mount exhaust and coolant but before Prop is added.

REF
Kevin the original ACE Drive designer/Twin conversion Pioneer in action

https://www.aceaviation.co.uk/redriveshttps://www.gk-engine.com/engine/8500ccengine/Kevin is using the 800cc 1000CC is also available...
https://www.summitracing.com/parts/msd-8210

This is a nice experiment, and should work. BUT, it is still a "rare" engine, and a one-off that would be difficult to achieve, AND it has none of the many-years-of-engineering-work that I am after. I want an engine that is totally reliable, has been the object of over 20 years of engineering work by the best engineers in the world, all of whom have been anxious to preserve their jobs! And is still being manufactured today. HAs parts available at every Honda dealer in the world, buy all your supplies either at the local gas station or Walmart, etc, etc. I will give up some things, like the lightest possible weight, for the advantages that the Honda possesses. I am especially anxious to see if ,y Coarse-Pitch-Prop/transmission idea will work out. As I have said before, my adaption makes NO changes to the engine, just the very simple attachment of a prop shaft adapter driven off the regular power output shaft of the engine by a dynafocal belt.
There can't be anything simpler, or more reliable, or less costly around. And potentially an engine combination that will give us the full capability of a very high-speed plane. It has cost me very little, and right now it is ready to put in the plane, except for the final fitting of the dynafocal belt.
However, I do have several other projects in the works that take precedence of this work. I am working on a virtually universal acceptance and use for my concepts of Hurricane Storm Surge Barriers. Simple, adaptable to the entire shoreline of the Gulf of Mexico, and Atlantic coastlines. About 1/100the the cost of current SSB designs. And totally reliable. Backed by the leading water control engineer for the ACoE, who says they will work. The engine work, tho, has my heart.
 
TD Good luck with the idea. I looked at the 1300 trans and engines parts on eBay, and the output shaft support looks flimsy by aircraft standards. Running a cog belt will probably help with the stresses but will not eliminate the power throughput issues and you are going to have lateral loads on the final drive bearing that is not designed for that use. Now here is my pea brain thought: the Honda is about 660 pounds and the engine drive with a heavy rider is only going to be pulling ~900 pounds max. Now consider the lowly Sonerai packed with two lard butts and pulling 4 gs. That's going to be in the neighborhood of 4,500-5,000 pounds being yanked around by the prop at max stress. That is a substantial load difference from the motorcycle, so your final drive and your engine drive power line (from pistons to prop) has to be able to handle that load. Maybe my thinking is wrong, but that is how I visualize the design problem. Consider a BRS for your test aircraft or maybe find an abandoned military airfield with miles of runway for testing, or both!
 
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