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Assessing alternative engine installation

D

Diego9

Member
Hello,
I am looking into the possibility to install an alternative engine on my 9 (under construction...).

The idea would be to use one of the standard engine mounts and cowling.
The first step is to get geometrical information or CAD and try to work out how to put the CoG in the right place (the engine is lighter than the o-320).
Vans was not very helpful with data...

Where can I find the following info?
- Engine mount geometry (or CAD) (conical mount looks easier for an adapter, I see Vans sell two types for o-320 and 0-290)
- Cowling geometry (or CAD). Also for this there are several versions... what is the difference? which one is the longest? How much extra material is provided on the flange to trim it to measure?
- o-320 geometry (mostly distance from the engine mount plane to the propeller flange)
- Typical mass and CoG of a full o-320 installation (need to establish a target that includes all FWF accessories)

The engine I would like to install is the turbo version of the MWFly Spirit 160 (not available yet but they are working on it...)

Thanks to anybody who can help getting the above information.
Regards
Diego
 
your message is typical of what new questions you will be asking every day of your build. it is way more work . and there is more chance that you make a bad decision that the engineer that designed the original plane never would have made. but i have done it.....twice. and the first i even had to build an engine mount and the main gear on the first. so if i can do it a lot of builders can. i would be careful of building anything around an engine that isn't even flying.
anyway, you've come to the right place for good answers.
 
Drawing 50 of the RV-6 plans has the dimensions of the dynafocal and conical mounts.
I believe the mount is identical between the 6, 7, and 9.

For you imm. need, the conical face is 10 5/8" from the firewall on the right side, and 10 7/8" from the firewall on the left side.

Watching a local fellow struggle with his VW powered Sonex installation (a very common, proven combo)... including a dead-stick landing.... You get my drift.
 
Dear all,
thanks for the feedback. I am aware that immature engines are a known source of pain (and risk...). At the moment I am just assessing the situation and I am still few years away from the first flight. The alternative would be a Rotax 915 which has gone through a test program recently on a customised 9.

About the MWFly engine, the aspirated version is flying since a few years. The first iteration had some problems on the reduction gearbox. These should be corrected in the second iteration (which is also flying already). The turbo version is aimed at keeping power at altitude and not to increase the sea level power. The engine was sized with this "upgrade" in mind.
If I decide to proceed with it, I will get assistance from the manufacturer for the FWF implementation.
The information requested in my first message is key to assess the complexity of the solution.
In my mind it will be a slightly longer cowling and some conveniently located ballast mass but need to run the numbers on some solid basis.

@blaplante: thanks for the first usable data!

Regards
Diego
 
I won't try to change your mind, though I'd echo the warnings others have mentioned. But hey, it's experimental aviation after all, so if you want to go down that path...

Van's publishes 3-view drawings of their entire fleet on their website. Combined with just a few measurements or plans pages, and the W&B template on Van's site, I think you could start piecing together a picture of what it would take for W&B. As you mentioned, the Rotax RV-9 would also be a good data point to reference. Robert Haag in the UK recently completed a pretty clean install of a Rotax in his RV-4, I'd think that his path to get there would be similar to what you'd go through. See the article below for some insight of what was required.

www.kitplanes.com

Rotax, Anyone? - KITPLANES

Robert Haag’s RV-4/600 is powered by a Rotax 915 iS engine.
www.kitplanes.com www.kitplanes.com

And for the 3-views.

www.vansaircraft.com

Downloads - Van's Aircraft Total Performance RV Kit Planes

Van’s provides a variety of downloadable items in support of kits and flying aircraft. Choose from the type of downloads you need below. RV-12/12iS avionics software downloads Dynon Skyview Garmin G3X Dynon D180 RV-12 and RV-12iS Electrical System Diagrams RV-12 misc. documents Canopy Warning...
www.vansaircraft.com www.vansaircraft.com
 
Experimental is just that, experimental, we don’t get innovation without it. That being said, the reliability and value of 2 similar aircraft with certified and alternative power plants aren’t exactly similar. I’m not saying certified power plants never fail. They can and do.

I’m going to point out the obvious. You’re going buy a -9 kit for in 50k+ and spend a couple 2-3 years of blood sweat and tears building it. You’ll probably put 20-30k in the avionics, and a similar amount for a certified engine and propeller. I don’t care what you insure it for. At the finish line, when your dream is about to take its first flight, do you want the safety and reliability of a certified engine? Or if things go sideways are you happy to get a check and (if you live long enough) the opportunity to do again?

Your choice. Not my circus, not my monkey. There is a reason most RV’s have certified engines out front.
 
rockyfatcat said:
Your choice. Not my circus, not my monkey. There is a reason most RV’s have certified engines out front.
Click to expand...
That's true - but most of that reason is because people are afraid to try something new (in general, not just engines in aircraft). A big portion of the fear of something new is hearing bad things about it from others, which is something you're not helping with right now.

If you have direct first-person information to share, that would be helpful. Standing up proudly and saying "That's dangerous!" is not helpful. Please tell us about your first-hand experience with an alternative engine, I'm sure we are all interested in the problems you faced and the solutions you found.
 
We see innovation in things throughout the world, including aviation. For me it is something to be applauded not feared. We now have electrically powered, hydrogen powered, alternative fuel powered planes not to mention the myriad of other innovations, none of which would have happened if some people were not willing to deviate from the historically normal. I admire those with the intestinal fortitude to be innovative and try the new ideas.

For me, I am not all that adventurous. The reality is with an alternative power plant you will probably sacrifice resale value and salability down the road as evidenced by the many Subie and other auto engine conversions. Just a consideration not a condemnation. I have personal experience trying an alternative fuel system (Rotec TBI) which did not work out well for me, although others had success. Not many O360 powered planes with that setup so little info to go on. I did not enjoy being a test pilot every time I went up while trying to figure out a solution, but that's just me. Back to the mainstream carb and all ok since. Personally I would split the difference between the brand new tech you are looking at and the somewhat tested "new" tech which is similar to what you are looking at. That being the UL Power line of engines. They have been around for almost 10 years and have a bit of a track record now. The big advantage I see is they are air cooled direct drive, so no gear box to fail, FADEC controlled and lighter than the Lycos with the same power availability. No liquid cooling system to deal with like the Spirit engine. Another big bonus is the fact that there are FWF kits available taking out a lot of the engineering requirements. Just my opinion, which is worth what you paid.

In terms of the OP, it's your plane. Build what you want, not what other people tell you. Do your research, make your decision and enjoy the ride! Best of luck!
 
RV7 To Go said:
…Personally I would split the difference between the brand new tech you are looking at and the somewhat tested "new" tech which is similar to what you are looking at. That being the UL Power line of engines. They have been around for almost 10 years and have a bit of a track record now. The big advantage I see is they are air cooled direct drive, so no gear box to fail, FADEC controlled and lighter than the Lycos with the same power availability. No liquid cooling system to deal with like the Spirit engine. Another big bonus is the fact that there are FWF kits available taking out a lot of the engineering requirements. Just my opinion, which is worth what you paid.
…
Click to expand...
I remember seeing MWFly motors on display at Sun&Fun back in about 2007. At that time they were in the 80 to 100hp engine market.
They were new to the North American market back then & looking for dealers, but was a well established choice in Italy & the European market, so there probably is a track record over there.
One thing that peaked my interest back then was that MW had a unique valve train system that smoothed out low rpm lumpiness & idle. Looking at their current offerings, they may have discarded this feature.
 
airguy said:
That's true - but most of that reason is because people are afraid to try something new (in general, not just engines in aircraft). A big portion of the fear of something new is hearing bad things about it from others, which is something you're not helping with right now.

If you have direct first-person information to share, that would be helpful. Standing up proudly and saying "That's dangerous!" is not helpful. Please tell us about your first-hand experience with an alternative engine, I'm sure we are all interested in the problems you faced and the solutions you found.
Click to expand...
As I said. It’s your choice. No risk no reward. I’m an A&P and KNOW certified engines, and know they work (mostly). My point was and still is that by the time you spent most of 100k and 3 or so years building your dream. Are you willing to roll the dice on an alternative engine? If things go sideways, your insurance will probably write you a check. But does that check put you in your dream-bird? Or will it just give you the funds give you enough to buy another 3 year project?
 
rockyfatcat said:
As I said. It’s your choice. No risk no reward. I’m an A&P and KNOW certified engines, and know they work (mostly). My point was and still is that by the time you spent most of 100k and 3 or so years building your dream. Are you willing to roll the dice on an alternative engine? If things go sideways, your insurance will probably write you a check. But does that check put you in your dream-bird? Or will it just give you the funds give you enough to buy another 3 year project?
Click to expand...
Really? How about those ECI cylinders? Superior crankshafts? The list of certified failures is long as well - just because they are "certified" doesn't mean they can't fail. Boeing seems to be having a swell time these days.

There was a time before "certified", you know. Moses didn't come down the mountain with PMA's to hand out.

Nobody is saying alternatives are "as safe" or "as good" as a certified powerplant until they have proven themselves in the market. But if you want to stand up and claim certified is all goodness and sunshine, I'm just going to have to giggle at you.
 
airguy said:
Really? How about those ECI cylinders? Superior crankshafts? The list of certified failures is long as well - just because they are "certified" doesn't mean they can't fail. Boeing seems to be having a swell time these days.

There was a time before "certified", you know. Moses didn't come down the mountain with PMA's to hand out.

Nobody is saying alternatives are "as safe" or "as good" as a certified powerplant until they have proven themselves in the market. But if you want to stand up and claim certified is all goodness and sunshine, I'm just going to have to giggle at you.
Click to expand...
Go back and read my original first post. Something about pointing out the obvious.

When did Boeing start making engines?

Do your own due diligence. Make your own best decisions. Nobody is stopping you or saying you are wrong.

Not my circus, not my monkey.
 
I remember when the Rotax got "certified" and started showing up on the diamond aircraft. Everybody saying I wouldn't fly behind a snowmobile engine, gearboxes are the devil, and pretty much all the same comments seen in every engine discussion on this forum and others.
I'm pretty sure some of those same people are making the same arguments for the Rotax, against the guys trying to develop the latest snowmobile engine from yamaha. People are funny.
 
Hello all,
interesting conversation... but I need some data please!
I will soon order the finish kit for my 9 and need to make up my mind about the engine choice. As mentioned before I am currently looking at the MWFly (I see they are at Sun'n'fun this year) and the Rotax 915.
If I decide to go to the Italian engine, I need to select the right engine mount and cowling as part of the kit.
For the engine mount I see Vans is offering two conical mounts (easier geometry if I need to have an adapter before the engine flange) for the O-290 and for the O-320. I understand the first is 2" longer to accommodate a lower mass engine.
For the cowling there are 3 options: O-235, O-320 and O-360. My understanding is that the first two engines have similar length between the mounting flange and the propeller flange and would expect the O-235 cowling is 2" longer than the O-320 one, to accommodate the longer mount.

Now, again, some questions:
Is the above about right?
I have been looking for the measures of the O-235 and O-320 (from mounting flange to propeller flange) but could not find it so far. Can anybody help? (measures cold be goor, a CAD file would be great!)
For the cowling, is this normally delivered "cut to measure" or is there some extra material (if so, how much more?) to be trimmed at the FW to tailor the installation?
Any weight information for a standard O-320 installation, including accessories, would also be useful.

Thanks again to the community,
Regards
Diego
 
Diego9 said:
Hello all,
interesting conversation... but I need some data please!
I will soon order the finish kit for my 9 and need to make up my mind about the engine choice. As mentioned before I am currently looking at the MWFly (I see they are at Sun'n'fun this year) and the Rotax 915.
If I decide to go to the Italian engine, I need to select the right engine mount and cowling as part of the kit.
For the engine mount I see Vans is offering two conical mounts (easier geometry if I need to have an adapter before the engine flange) for the O-290 and for the O-320. I understand the first is 2" longer to accommodate a lower mass engine.
For the cowling there are 3 options: O-235, O-320 and O-360. My understanding is that the first two engines have similar length between the mounting flange and the propeller flange and would expect the O-235 cowling is 2" longer than the O-320 one, to accommodate the longer mount.

Now, again, some questions:
Is the above about right?
I have been looking for the measures of the O-235 and O-320 (from mounting flange to propeller flange) but could not find it so far. Can anybody help? (measures cold be goor, a CAD file would be great!)
For the cowling, is this normally delivered "cut to measure" or is there some extra material (if so, how much more?) to be trimmed at the FW to tailor the installation?
Any weight information for a standard O-320 installation, including accessories, would also be useful.

Thanks again to the community,
Regards
Diego
Click to expand...
Diego, what you've stated is about right. Realistically it won't make much difference, because either of your engine choices will be such a far offshoot of the factory design, its a little bit like asking:
"I want to build a row boat, should I make it from guitar's or violins?"

Most cowlings come with around 2 inches extra to be trimmed. You're probably going to need closer to 10" to get that engine where you want. Again, the Lockwood/Rotax RV-9 will be the closest thing to what you're hoping to achieve.
I believe Lockwood is developing a firewall-forward kit for the 915/916 RV-9. The value of Phil and team's knowledge being poured into that cannot be overstated if you want to go down that (or a similar) path.
 
Diego- I would suggest you go with the conical 320 mount, you will most likely custom fabricate a tubular extension forward of that to the MW conical mount brackets.
Why 320 vs 290/235 mount (if there is a difference)? Would be easier to resell if the experiment doesn’t work out, or would be still viable if you were to change out to a 320 (minimally reasonably acceptable Lycoming engine for your airframe) at a later date.
Cowling, I would go with a 360 injected cowl. Why? Easiest to resell to someone later. What ever Vans cowl you choose will not easily adapt to a MW installation, you will end up extending it’s length significantly as well as needing to do a lot of inlet changes. You will be able to better map out all your custom dimensions if you do have a (what ever) cowl on hand. Also any Vans cowl will be CAVERNOUS around a MW installation.
 
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