RV-12 with Honda/Viking Engine Flown

[Kyle Boatright]

Congratulations to Ron! I hope this powerplant proves viable. It would be great if Ron would publish test flight reports - I'm sure there are a lot of interested people.

[vernhendershott]

Originally Posted by Peterk

Since one of the requirements to fly as a sport pilot is that you are in an aircraft with several restrictions, one of which is speed. The speed "limit" is 120 kts at the manufacturer's recommended maximum RPM at sea level. If you go amateur built and put a Corvair/Honda/VW or whatever car engine on it, who is the manufacturer and if not the engine designer, who decides that maximum? And what is it based on? Just like you can't put any old wing on there (stall speed restriction) how can you register such an aircraft as LSA?

I know Van's certified their SLSA (RV12) to the guidelines, I'm not enough of an engineer to know how you do it with an alternative engine.

You are on the right track. The speed restriction is for 120 Kts. at sea level in level flight at maximum certified continuous power, there is a Cub look a like that uses the Lyc. 180 HP engine restricting the 180 HP to five minutes and then restricting Maximum Continuous Power to 80 HP and they seem to be getting away with it so far.

They did an interesting move when the FAA wrote the Light Sport Rules they said words to the effect that we could use any aircraft that fit the rules no mater how it was certified, so aircraft like J-3 Cubs and Luscombe 8-A's are legal to fly as Light Sport Aircraft by a Pilot flying on the privileges of a Light Sport Pilot; such as a older ATP rated pilot who no longer maintains his/her medical. The same is true for Experimental Home Built Aircraft, which is to say if the aircraft has always been compliant with the requirement of the Light Sport Aircraft Rules, in this case a RV-12 built as an EAB so that it could have an alternate engine like the Viking, so long as the aircraft stays within the LSA rules for aircraft it can be flown by a Light Sport Pilot. Should it ever fail to meet the requirements then it is just another fine home built and you must be a Student Pilot with a Medical or better to fly it. In the recent post on the Viking powered RV-12 touting a speed of 131 Kts in the airport pattern, if this were at the established Maximum Continuous Power Limit then the aircraft would no longer qualify for a Light Sport Pilot to fly it legally. I assume in this case they had a higher power setting and they will not receive a call from the FSDO anytime soon.

For an EAB aircraft the builder sets all of the operating limitations for the particular aircraft and they are accepted by the FAA inspector or DAR, who may be more restrictive if the inspector feels that the proposed limitations are not safe or reasonable. If you built a nice RV-8 which Van's recommends a Maximum Gross Weight of 1850 pounds and you ask the inspector to list the Maximum Gross Weight as 2500 pounds the inspector would likely say no or ask you to show some engineering documentation that the change from the Kit Manufactures recommendation was sound and reasonable. In the case of the RV-12 with the Viking Engine the builder could set the Maximum Continuous Power limit at any number of HP that would allow the aircraft to qualify as a Light Sport Compliant Aircraft, perhaps a limit of around 80 HP would serve the requirement. You can still use more power for Take Off or an En-route Climb as the restriction is normally set for 5 minutes at a higher power level.

For what it is worth Boeing will sell you a modification for aircraft like the B-767 that changes the Take-Off power limit from five minutes to 10 minutes as there are some commercial airports in values that you need full power for more than five minutes to clear all the mountains or you have to lower the Gross Take-Off Weight considerably for that airport to comply with the certification performance requirements for large aircraft.

The only kit aircraft that can be registered as Light Sport Aircraft are ELSA compliant kits such as the RV-12 and I have heard that the Rans 19 can be offered as an ELSA kit, but it is generally not. There may be a few others and as you know the manufacture must build a SLSA compliant aircraft and then all ELSA kits must be identical copies of the SLSA aircraft, this is a significant restriction for a kit builder to comply with and we can all be very proud of the way Van's has fully complied with both the letter and the spirit of the regulations in this area.

Best regards,
Vern

[skydiverlv]

The Viking has redundent electronic ignition systems and two fuel pump/filtration inlets all fused seperately. Single spark plugs per cylinder with seperate coils. A flick of a switch and you are on the redundent system. Also fuel injection.

Originally Posted by WingedFrog

If it's still competitive, that could be a game changer, even with its single ignition.

[rvbuilder2002]

Originally Posted by Peterk

Since one of the requirements to fly as a sport pilot is that you are in an aircraft with several restrictions, one of which is speed. The speed "limit" is 120 kts at the manufacturer's recommended maximum RPM at sea level.

The actual requirement is 120 kts at max. continuous power. Power is derived from RPM and manifold pressure. So, you technically can't just set a propeller pitch to limit sea level speed with flight at say, half throttle to stay below 120 kts, and be in compliance.

Originally Posted by DonFromTX

The ELSA RV12 apparently comes in quite a bit under the LSA figures according to Vans web site, so there is wiggle room for better than stock performance.

This statement is not true.
If you use maximum continuous power at sea level (as described above) as the baseline with a fixed pitch propeller (as required by LSA), you will not be able to attain that same speed at all altitudes.
Also keep in mind that the specified speed #'s on Van's site were without wheel pants and the nose leg fairing and at gross weight at 7500 ft.

[JoeM]

The origional post says 131MPH, not knots. Within LSA parameters.

[DonFromTX]

Originally Posted by rvbuilder2002;Also keep in mind that the specified speed #'s on Van's site were without wheel pants and the nose leg fairing and at [U

gross weight[/u] at 7500 ft.

Which means we builders don't even know if it is legal with pants and fairings. Can you divulge the actual tested speed at sea level at max cont power? Seems like something that should be available to us as builders rather than some 7500 foot figure that has nothing to do with ELSA.

[David-aviator]

Originally Posted by rvbuilder2002

The actual requirement is 120 kts at max. continuous power. Power is derived from RPM and manifold pressure. So, you technically can't just set a propeller pitch to limit sea level speed with flight at say, half throttle to stay below 120 kts, and be in compliance.

The interpretation you present is not consistent with the Carbon Cub kit. From their web site -

"The builder is legal to fly the Carbon Cub EX as a "Light Sport" pilot as long as the kit is certified at a maximum weight of 1,320 lbs. Our kit was tested to ASTM standards at a gross weight of 1,865 lbs. If you decide to set the gross weight at 1,865 lbs, you will not be allowed to fly as a "Light Sport" pilot; and you will need a medical and a private pilots license."

This airplane, which I saw at OSH, had a placard on the instrument panel limiting power to 80 HP in order to comply with LSA max speed rules. It is powered by a Lycoming 180 HP engine and is restricted to 5 minutes at take off power. After 5 minutes, it has rpm restrictions to meet the letter of the rule on speed. I do not believe the LSA rules preclude what Carbon Cub is doing to meet max speed rules or they would not be doing it.

If this air plane is approved by the FAA for LSA, the precedent has been set. Pulling the power back with any engine, as per a placard limiting HP, is one way to meet the max speed requirments.

[DonFromTX]

And if you "forget" to pull back on the throttle for the whole trip, you have not violated even one bit the LSA rules.
My question there is since the engine MANUFACTURER has not made this restriction in power, is it in fact OK for LSA requirements? For the 170 mph Sonex with 3300 Jabiru, it is not Sonex that is making the limit, it is Jabiru. Rumor has it that as engine maker, John Monnet is going to put a different plate on the AeroVee for the OneX just to keep it legal. The Viking may have to have a limit plate as well, easy to do if you are making the engine.

[Mike S]

Originally Posted by vernhendershott

there is a Cub look a like that uses the Lyc. 180 HP engine restricting the 180 HP to five minutes and then restricting Maximum Continuous Power to 80 HP and they seem to be getting away with it so far.

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In the case of the RV-12 with the Viking Engine the builder could set the Maximum Continuous Power limit at any number of HP that would allow the aircraft to qualify as a Light Sport Compliant Aircraft, perhaps a limit of around 80 HP would serve the requirement. You can still use more power for Take Off or an En-route Climb as the restriction is normally set for 5 minutes at a higher power level.

Originally Posted by David-aviator

"The builder is legal to fly the Carbon Cub EX as a "Light Sport" pilot as long as the kit is certified at a maximum weight of 1,320 lbs. Our kit was tested to ASTM standards at a gross weight of 1,865 lbs.

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This airplane, which I saw at OSH, had a placard on the instrument panel limiting power to 80 HP in order to comply with LSA max speed rules. It is powered by a Lycoming 180 HP engine and is restricted to 5 minutes at take off power. After 5 minutes, ] it has rpm restrictions to meet the letter of the rule on speed.

If this air plane is approved by the FAA for LSA, the precedent has been set. Pulling the power back with any engine, as per a placard limiting HP, is one way to meet the max speed requirements.

Originally Posted by DonFromTX

And if you "forget" to pull back on the throttle for the whole trip, you have not violated even one bit the LSA rules.

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Rumor has it that as engine maker, John Monnet is going to put a different plate on the AeroVee for the OneX just to keep it legal. The Viking may have to have a limit plate as well, easy to do if you are making the engine.

And folks wonder why the Experimental crowd is not looked on favorably in a lot of aviation circles, and why the FAA has been breathing down our necks.

If there was this much thought and effort put into trying to COMPLY with the intent of the regs, instead of figuring out how to exploit a loophole to get away with something clearly not part of the intent, then we might be able to stop looking over our shoulders quite as much.

[DonFromTX]

It should not be up to us to determine the "intent", not sure where you found the "intent" of the rules, not in anything I have found.
They COULD have simply said no faster than 120knots anytime, anywhere, if you are a sport pilot, but they did not. To the best of my knowledge the "intent" was to stimulate the aircraft industry and the number of pilots.