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Engine options
- Thread starter Blain
- Start date
I'm afraid that the O-200 would be a bit heavy for the RV-12. You might be able to make it work but you would be sacrificing needed useful load.
I really like the UL Power engines. Their weight is within the Rotax range. And no re-drive, no coolant tanks, no radiators, hoses or external oil tanks.
The DA-20 with the Continental really is a delight to fly.
Phyrcooler
Well Known Member
There’s a couple folks that headed down the UL route with their RV-12’s. Search around here or on Facebook. The 12 was optimized around the Rotax. It’ll be interesting to see a couple with UL’s and compare their performance and W&B numbers. Might be even more interesting if MOSAIC ever comes to fruition.
I think if you compare all up "flying weight" including radiator, oil & coolant tanks, coolant, hoses, etc. you will find the UL Power comes in slightly lighter.
The UL 260is is about 160 lbs. The Rotax 912 ULS comes in closer to 190 lbs. The UL 350i is 116 hp @ 172 lbs. (flying weight).
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I won't try to convert you from the flat earth theory either.
Pffft. Round earth; how ridiculous.
Not sure the beliefs are comparable, although I do agree that one should remain open to persuasion via appropriate evidence.
Why look only to the past? The -12 is a light aircraft and going electric should be an easy (well, nothing about it will be easy) conversion. The batteries would need to be mounted firewall forward to help maintain weight and balance parameters.
Just this month someone on the ramp complimented me on my -12 paintwork then followed up with "but running 5,500 RPM that every flight is a crap shoot for when that engine will just fly apart into a thousand pieces."Not sure the beliefs are comparable, although I do agree that one should remain open to persuasion via appropriate evidence.
I asked him how Ferrari, with engines spinning in excess of 9,500 RPM, ever convinces anyone to buy one of those vehicles.
flightdoc101
Member
An oversquare engine is built to turn fast. The short stroke makes it a piece of cake.
I’m not a fan of Rotax mostly for the reasons Mel pointed out earlier.
Just finished doing a 912ULS on a Zenith and engine weight including accessories and oil came in @ about 179 lbs.
Even if you come in at 170, isn't that within the range of the UL @ 172 lbs?
I think an interesting parallel is the Vashon Ranger with the O-200D. Empty weight is advertised as 875 lb with a useful load of 445 lbs at LSA max gross weight. You could expect something similar weight wise for an RV-12, along with a forward CG that you might have to take some actions to fix (battery in the tail cone for example).
John Salak
RV-12 N896HS
sansoneservices
Well Known Member
I'm very familiar with the rotax 912 and I'm also not a fan. Unfortunately for the -12 you kinda have no choice. I would love a cont O200 but there goes your useful load
I’m curious what is included in the 160 -170 weight. Rotax claims a 912ULS is 121 - 128 pounds for the engine, oil tank, and hoses. The estimate for the exhaust system varies 13 - 22 pounds. Were you included the mount and propeller?
As already mentioned, I don’t recall the specifics (16 years ago) so it may have included engine mount assemblies, coolant radiator and exhaust, which were all custom designed components for the RV-12. Only the standard oil cooler and overflow bottle were used. It would also include three long oil hoses.
Might have also included propeller, but I don’t think so.
csmith3603
Well Known Member
Hi Blain; Flying a -12 with a Rotax 912iS is a scream! You pay attention to all Rotax notices and inspections!
Its fuel injection. The 912ULS has twin carburetor's that you must maintain!
I am finishing a -12 with a dinosaur engine using a Aero Momentum 117HP fuel injection engine, mount and hub.
Can wait to fly 40 hours off.... Grin
“Scream” explains it perfectly. I don’t want a power plant that turns 5800rpm. Nor do I want a radiator or a gearbox. I think it’s a generational thing. Just a retro air cooled 4 banger.
Why a -12 then??? Take a look at the -9; very nice timeless design.
MechaSteve
Well Known Member
I would be very interested to hear the measured Basic Empty Weight of any flying examples of alternate engines.
sansoneservices
Well Known Member
Call me old fashioned, I would put a continental c-90 on a rv12.. 90hp @207 pounds.. rotax 912 is 170 pounds if you include 20 lbs radiator.. I posted earlier the rv12 requires the 912, support is one reason, but I really dislike the ridiculous high RPM and the reduction
I previously posted that the RV 12 installation was 160 to 170 pounds.
That was to be conservative since I don’t remember the specific number, but I’m pretty sure it’s close to 160.
So that would put the C-90, about 45 pounds heavier.
That may not seem like a lot, but on an airplane whose empty weight is under 800 pounds, it is.
I have posted previously that I know of at least one RV 12 builder that installed an 0–200. After doing the weight and balance, the engine was replaced with a Rotax before even doing a single flight because it wasn’t going to be practical to get the weight and balance adjusted.
There’s not all that big a difference in weight between the 0–200 and a C – 90.
sansoneservices
Well Known Member
C90 is about 15 lbs lighter than a o200.. if my math is correct the difference between c90 and 912 is about 35 pounds. That could be neutralized with a lightweight prop. If cg is a concern the battery could be moved aft. As stated I dislike the very high rpm and reduction gearbox.
Engines with geared propellers are not new in aircraft, nothing to be afraid of. Here are a few examples of aircraft from the past that had geared engine / props.
P-51 Mustang (World War II)
Engine: Rolls-Royce Merlin V-12
F4U Corsair (World War II)
Engine: Pratt & Whitney R-2800 Double Wasp (Radial Engine)
Consolidated B-24 Liberator (World War II)
Engine: Pratt & Whitney R-1830 Twin Wasp (Radial Engine)
Lockheed P-38 Lightning (World War II)
Engine: Allison V-1710 V-12
De Havilland Mosquito (World War II)
Engine: Rolls-Royce Merlin V-12
P-51 Mustang (World War II)
Engine: Rolls-Royce Merlin V-12
F4U Corsair (World War II)
Engine: Pratt & Whitney R-2800 Double Wasp (Radial Engine)
Consolidated B-24 Liberator (World War II)
Engine: Pratt & Whitney R-1830 Twin Wasp (Radial Engine)
Lockheed P-38 Lightning (World War II)
Engine: Allison V-1710 V-12
De Havilland Mosquito (World War II)
Engine: Rolls-Royce Merlin V-12
sansoneservices
Well Known Member
Yes and the rotax gearbox is not robust by any stretch. I've assisted teardowns of P&W r2800 radials, been to the Rotax shop in Sebring, assisted repairs to their gearbox. They have acceptance with consumers, and a decent warranty, just not a big fan
How would you neutralize this with a lightweight prop when the RV-12/IS were designed around practically the lightest-weight composite prop out there (paired with an already light engine)?
The engineering team spend a lot time designing the 12's airframe to perfectly accommodate the 912ULS and iS, literally from the tailcone to the spinner tip. Taking advantage of that certainly outweighs (pun intended) gearbox frustration in my opinion.
sansoneservices
Well Known Member
My earlier post stated the 912 is the only practical choice. I'm saying my preference if I was building a -12 would be a Continental C-90.. certainly it would be more involved but I would succeed
My EAB Honda Viking 110's last W&B came in at 863 lb empty weight, however I just installed an E-Prop to replace the 2-blade Sensenich which should drop about 9.5 pounds of weight. I am running dual fuel pumps and dual Earth-X batteries in the tailcone to keep the CG in range. Weight adders include 100% custom wiring, Dynon IFR capable panel, Avidyne IFD540 (15 pounds), wheel pants, Comfort foam seats (worth the extra weight), full interior. I weighed the engine/GB and accessories (alternator & radiator) at 192 pounds.
I expect the lightweight O-200D used in the Vashon Ranger would yield somewhere near an 815-825 lb empty weight in an otherwise stock VFR RV-12. The problem is the forward CG would require moving the battery to the tailcone (somewhat standard RV solution) and perhaps some additional ballast as well. Too bad the EPI O-200D replacement engine has never made it to production (https://epi-eng.com/aircraft_engine_products/aircooled_4-cyl_aircraft_engine.htm). The UL Power 260iS might be a good choice for a direct drive engine at 168 lbs that would have minimal impact on the RV-12 design empty weight.
John Salak
RV-12 N896HS
I also went this route, RV12iS with AeroMomentum AM15 117hp, 3 Blade Sensenich Prop left turn, 9.8lbs
here the numbers, maybe this info helps for any decision
The empty weight on the scales including oil and coolant was 404.00 kg including 5.7 kg of
a lead block at the end of the empennage (access door), the weight of the front gear leg at this time was 95kg. Later I added another 4kg of lead, otherwise, I couldn't do a normal flare or even stall.
After some issues, I decided to switch to Rotax912iS. Luckily, I have built the plane to the firewall forward according to Van's plans, Rotax fuel pumps already in the back.
With the Rotax 912iS, 2 Blade Sensenich, fully equipped, the empty weight is now 365kg front wheel 68.50kg the plane flies as designed.
My personal summary for the RV-12, other aircraft and or engine type may be different.
Yes, it is possible to use a car engine conversion with the RV12.
I agree, the take-off and climb performance are impressive with more power.
But the price is high, time-consuming installation, lower usable weight, Engine reliability, engine wiring, ECU brand and parameters,
backup systems gave me a lot of headache during build and flying.
Unknown stress on the heavier nose gear leg and finally the resell value.
Building is cool, relaxed flying is great
If this is true, you must be using a really heavy propeller right now (something other than the Sensenich ground adjustable?)
The Sensenich propeller used on the rotax powered RV – 12 only weighs about 10 pounds.
890 lbs versus 804 pounds with the Rotax.I also went this route, RV12iS with AeroMomentum AM15 117hp, 3 Blade Sensenich Prop left turn, 9.8lbs
here the numbers, maybe this info helps for any decision
The empty weight on the scales including oil and coolant was 404.00 kg including 5.7 kg of
a lead block at the end of the empennage (access door), the weight of the front gear leg at this time was 95kg. Later I added another 4kg of lead, otherwise, I couldn't do a normal flare or even stall.
After some issues, I decided to switch to Rotax912iS. Luckily, I have built the plane to the firewall forward according to Van's plans, Rotax fuel pumps already in the back.
With the Rotax 912iS, 2 Blade Sensenich, fully equipped, the empty weight is now 365kg front wheel 68.50kg the plane flies as designed.
My personal summary for the RV-12, other aircraft and or engine type may be different.
Yes, it is possible to use a car engine conversion with the RV12.
I agree, the take-off and climb performance are impressive with more power.
But the price is high, time-consuming installation, lower usable weight, Engine reliability, engine wiring, ECU brand and parameters,
backup systems gave me a lot of headache during build and flying.
Unknown stress on the heavier nose gear leg and finally the resell value.
Building is cool, relaxed flying is great
Exactly about what I would expect.
All of the SLSA factory production Aircraft weigh between 795 and 805 pounds depending on whether they are the upgraded IFR versions or not, and this is with a pretty complex base coat, clearcoat paint scheme.
Same Sensenich prop and hub as a Rotax RV-12 with L vs R blades. The total weight of the 2 prop blades, hub, 2" spacer, 18 bolts, 6 prop flange threaded bushings, spinner backing plate and spinner was 15 lb 5 oz. E-Prop blades (3), hub, spinner, and 6 nuts were 6 lb 0 oz. on the same scale.
John Salak
RV-12 N896HS
If you're interested in a -12 with a UL Power engine, you might want to speak with Hangar10Aero.com. They've just finished building one. Ended up within a couple pounds of the 912iS-powered -12 I built, but CG is farther forward because of the different motor mount. Their prior work building the Hatz Bantam (also UL Powered) was featured in Sport Aviation; and they've built other kinds.
Thanks for the lead.
2 inch extension (not used on a Rotax powered RV-12) and the additional 6 bolts (only 12 used on the Rotax RV-12) explains at least some of the weight difference...
It is interesting to see people suggesting alternative engines (UL et. ) with barely any installation numbers to speak of ( and thus hardly any hard data regarding reliability ) vs Rotax with their 50 000 installations - because of “high rpm” or a “gearbox”
Personally I find it more entertaining to hear from the people who say they are choosing an alternative to avoid dealing with SBs.
So far the alternatives do not present benefits that outweigh the risks for me, but I'm pretty conservative or as some might say 'chicken stuff'. I love to see other people doing it and encourage people like Blain to do WTF they want. For us skeptics, one way to answer these questions is having more builders attempt to build a better mousetrap.
Please please build your continental powered RV-12. I want to see it.
Well, of course … it is called experimental aviation for a reason but I still think that vast majority of builders are here just to build a reliable and modern plane that they are in control of in terms of of maintenance and limit their “experimenting” to minor peripheral things …Personally I find it more entertaining to hear from the people who say they are choosing an alternative to avoid dealing with SBs.
So far the alternatives do not present benefits that outweigh the risks for me, but I'm pretty conservative or as some might say 'chicken stuff'. I love to see other people doing it and encourage people like Blain to do WTF they want. For us skeptics, one way to answer these questions is having more builders attempt to build a better mousetrap.
Please please build your continental powered RV-12. I want to see it.
The “ let me improve on this spar attachment setup cause I probably can do it better than Vans and frankly, there is not enough excitement in my life anyway so why not” mentality is probably pretty rare …
Now what about committing and givin'birth to that very first Super Rocket RV-12?
Of course, anyone will be respectful of those MTOM, W&B, Vne, structural and what else limits, and maybe some beefing up might be required after all...
For sure, some fancy Lycoming IO-720, or equivalent would nicely propel that unique RV
Of course, anyone will be respectful of those MTOM, W&B, Vne, structural and what else limits, and maybe some beefing up might be required after all...
For sure, some fancy Lycoming IO-720, or equivalent would nicely propel that unique RV
How about with a PBS Aerospace PBS TP100 then?Now what about committing and givin'birth to that very first Super Rocket RV-12?
Of course, anyone will be respectful of those MTOM, W&B, Vne, structural and what else limits, and maybe some beefing up might be required after all...
For sure, some fancy Lycoming IO-720, or equivalent would nicely propel that unique RV
