The Rotax RV-9 IS real!

[BigCat77]

I had an interesting phone conversation yesterday afternoon with Phil Lockwood, of Lockwood Aviation, about this project. Just a few tidbits I gathered from the conversation...

• They are planning on releasing a full hardware "kit" to builders for their own installation. Their shop and their labor could be made available for the installation, but that's not being looked at yet, the plan is for owner-install of a FWF kit.
• Half-fuel solo climbs of 1800 fpm are being seen into the upper teens at full power - though the Rotax is time-limited for full power.
• Cruise speeds in the low 190's knots true in the 17k-19k altitudes in normal "go-fast" mode with higher fuel burn, and 10 knots slower in eco mode (LOP).
• Good cooling results with the second iteration of the cowl, but they are going to put the 916 in now and test with that to make sure enough cooling is available for the higher takeoff-rated power of the 916. Both the 915 and 916 are rated for 135 continuous.
• 135hp continuous is available to "about 19,000 feet" according to Phil, at which point it starts to taper off as the turbo is doing everything it can, there ain't nothing left.
• Service ceiling will be FL230 due to high bearing rpm on the turbo.
• They expect to be in production by the end of this year. We did not discuss price - I didn't ask and he didn't volunteer.
• The rudder on the test aircraft is different - some readers here have spotted that it was replaced with not-quite-matching paint, including me. Phil said the rudder was replaced due to damage (not related to testing) and is the exact same design. No control surfaces or empennage surfaces were changed for the increase in Vne (approved by Vans). He told me that Vans approved using the IAS of 182 knots for Vne at altitude as a limiting factor rather than true airspeed. I believe EAA reported 205 ktas (which would be about 147 kias at FL190, depending on temperature) being a limitation, so maybe there is more to this story. This indicates to me (my opinion and zero confirmation) that flutter is not the primary concern for the Vne on the 9/9A model, at least at these expected operating altitudes.
• A dorsal fin was added from the aft end of the canopy slide track (for a slider) back to the vertical stabilizer to improved yaw stability, in order to counter the longer cowl on the nose.

I would like to read the 205ktas EAA thing you referenced. I would also like to hear folks on this thread discussing on another turbo project for the airframe. Teal Jenkins put a 998T Yamaha (stock 205hp critical altitude 8,500 & and almost as lite as 915) in a rv9 and had several hundred hrs development time before a fuel line maintenance issue caused a fire and successful off airport landing. Anyway it too seems like a hell of a go fast idea. I am new here but will try to drop a YouTube link.

 

[Michael Seager]

Agreed. Down low any RV is going to have a rough ride in thermals or mechanical turbulence. The 9A wing lets you quite easily climb above it.

Wondering why you think the RV9 wing works better than an RV-7 wing at altitude. My experience is they both fly the same speed on the same horsepower. I never seen any climb advantage. The RV-9 wing does fly slower!!!!

 

[skylor]

Wondering why you think the RV9 wing works better than an RV-7 wing at altitude. My experience is they both fly the same speed on the same horsepower. I never seen any climb advantage. The RV-9 wing does fly slower!!!!

Anyone that doubts the earlier RV wing’s high altitude capability needs to read about Bruce Bohannon and the Exxon Flying Tiger!

Skylor

 

[NORDO Industries LLC]

rv916.com is now live.

Complete FWF kit, including MT CS prop. December 2024 delivery estimate. No pricing yet.

80 lb weight savings. You’ll probably want to spend some of that freed-up budget on an O2 system.

• 190 knots true ASI at 18,000 ft on 10.5 gph
• 180 knots true ASI at 18,000 ft on 7.9 gph
• 176 knots true ASI at 18,000 ft on 7.4gph
• 170 knots true ASI at 12,000 ft on 7.5 gph
• 180 knots true ASI at 12,000 ft on 10.5 gph
• 150 knots true ASI at 3,500 ft on 7.5 gph
• 160 knots true ASI at 3,500 ft on 10.4 gph

 

[scsmith]

Wondering why you think the RV9 wing works better than an RV-7 wing at altitude. My experience is they both fly the same speed on the same horsepower. I never seen any climb advantage. The RV-9 wing does fly slower!!!

High altitude performance is all about aspect ratio. And manifold pressure. But as far as the wing goes...The -9 is going to do better at 17,000 ft than the -7.

 

[jliltd]

High altitude performance is all about aspect ratio. And manifold pressure. But as far as the wing goes...The -9 is going to do better at 17,000 ft than the -7.

THIS /\ Steve the aeronautical engineer nailed it.

The 9 has less induced drag due to a higher aspect ratio wing. It's a similar reason that high performance sail planes and the U-2 have high aspect ratio wings. The difference being more pronounced with TAS in thinner air. That's why 180hp 9's can cruise right at or above Vne and the pilots of the big engine equipped 9's have to pull the power back in cruise to remain below Vne. Which is why Vans does not recommend larger engines in the 9. Remember the 9 was originally designed for an O-235. The standard stubby wings of the other Vans models are more of a sport/maneuvering/aerobatic wing. The 9's aren't as aerobatic but can out-run an equivalent 4/6/7/8 at altitude with a smaller engine. The 9 can also tend to be "bumpier" in turbulence due to the lighter wing loading.

I think a 9 matched with a Rotax 916is will be an incredible ride.

 

[jliltd]

Anyone that doubts the earlier RV wing’s high altitude capability needs to read about Bruce Bohannon and the Exxon Flying Tiger!

Skylor

The Flying Tiger had a higher-aspect ratio wing. They started with RV4 wings and then re-designed them with a longer span.

 

[rvbuilder2002]

Remember the 9 was originally designed for an O-235.

Slight clarification…
The RV-9(A) was right from the very beginning designed to use the 0–320, with an option to use a smaller engine, if the builder chose to.
Everything else you wrote I totally agree with, with the exception of implying that at high altitude, even with a smaller engine that the RV-9 is just as fast as the short wing airplanes because of the benefit of the high aspect ratio wing.
I flew the original prototype with the 0–235L2C (Cessna 152) engine some so I
know this not to be true, though it is pretty fast for what it is.