Rotax 915iS in RV9

[EdH]

Rotax certified the 916iS last summer, 157hp for 5 mins then 134hp max continuous from sea level to 23,000ft. No fanfare... for a covert client.

[tjo]

The problem with the Rotax 915 from my perspective:
- weight and balance
- high cost
- could run mogas, but impractical due to on airport availability (or lack of)
- limited or expensive constant speed prop availability
- roll your own FWF package

If you can overcome these, or they are not an issue for you, then do it. Performance should be fine. My choice, though, is a Lycoming.

Tim

[jliltd]

Originally Posted by NinerBikes

Need to add some weight to the nose? Get a constant speed prop for the 915iS

My understanding is that the 915is needs a constant-speed prop to operate properly. It has something to do with how the oil circulates through the crankshaft. At least that was what Rotax stipulated four years ago when the 915is was hitting the real production market. That was one of the "no go" items for USA-based by LSAs as constant speed props ae not allowed. Plus having one could easily have pushed the slicker LSAs past the maximum allowed. Perhaps there has been an accommodation like a crankshaft oil bypass valve for fixed-pitched propellers in the last 4 years.

Jim

[NordicDave]

An STC is now available for the Rotax retrofit to a Cessna 150.

[jliltd]

That's an amazing development for the Cessna 150. A Rotax 915is with constant-speed prop STC. Add a tailwheel conversion to an early model and it would be a great bush plane.

[Major-Tom]

Originally Posted by Diego9

combination of moving the engine FW and adding some mass in the engine area

A ballistic parashute system would be a nice extra mass for many builders! The european version of the CH650 has ist BRS firewall forward.

[ccast04]

I'm sure this has been posted before, but seems like the mothership is thinking the same thing and it works. Would be interested to hear what they have done to fix potential W&B issues.

https://registry.faa.gov/AircraftInq...umberTxt=179RV

[Dreamin9]

The Rotax engines are a different breed. Might want to be sure you have a local “wrench” who is knowledgeable/experienced in their quirks.

Resale might be an issue, much smaller market for buying a used plane with what many consider, right or wrong, an oddball engine.

Carl

[hpmicrowave]

In a discussion with a reliable source at the end of Sun n Fun this past weekend I was told about an ongoing flight test program with a RV9 and a Rotax915is. The source said the upgraded RV9 can easily keep up with the RV fleet at 9k and above. The conversion package his company is working on will be complete with prop, cowling, and firewall forward and will be brought out soon when all the testing and details are complete.

On the other hand this might just be a Rotax POC working with Vans Aircraft developing the firewall forward design details for the RV15??

From my experience with the 915is I believe it's one, if not the most sophiscated reciprocating aircraft engine available today. It's fully computerized with redundant computer, fuel and ignition systems, turbo charged and inter cooled, gets full power to around 15k, computer will always work to get the most efficient fuel power combination with the single power lever. Burns mogas including ethanol mogas as well as avgas. And uses oil like a modern car engine does. Oil changes every 100 hours using unleaded fuel and 50 hours with leaded avgas. It's not cheap but it's operating costs will make it a good option for many folks.

[GeoffM]

Updated 9 kit with final-size holes, more pre-fabed parts, updated plans, etc. and the option for a 915is? Sign me up.

That's the RV I'd build. Simplicity of the new kits with modern engine and kit would be amazing.