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RV-12 with CS prop?

David-aviator

Well Known Member
Just an update.
I?ve been helping friend complete RV-12 and have decided to go EAB certification rather Vans LSA.
I may end up with this airplane and looking forward, a CS prop like Katana.
Anyone here thinking likewise?
Am adjusting to Rotax after Lycoming Subaru back to
Lycoming. Rotax is much better than Subaru, but jury is still out compared to Lycoming. Rotax sure has more hoses, tubes, wires, complexity with 2 carbs than Lycoming but lots of guys like the engine.

dd
 
I can't imagine a constant speed prop being a substantial improvement on an RV-12.
The -12 has a relative small speed range envelope and jumps off the ground with a F/P.
Plus it can never be flown by a sport pilot, even if you later changed back to a F/P.
 
If you are considering E-AB, perhaps the UL350IS would be a better powerplant than the Rotax. Do a search around here.

Also, is it possible to have the pitot tube thru the hub with a CS prop? Or will it now be wing mount and now the wings are no longer removable?

I think your friend doing the build should be asking the questions about this, as an E-LSA RV-12 has a bit higher resale value than a E-AB. 2nd owner of an E-LSA can take a 16 hour course and do annual and 100 hr inpsections themselves, instead of paying an AP to do it, as required on an E-AB lowering the cost of maintenance and flying per hour.

There's no guarantee you'll be the second owner. I'd think most builders would want to get top $ for resale out of the plane they built.... E-LSA seems to be the best way to recoup the money spent up front.
 
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RV-12 with CS prop

I am not advocating for this but I saw a RV-12 at Sun 'N Fun with a UL Power engine on it. The thing that was most notable to me is that there is room to work in the engine compartment with the UL Power engine. I don't know about reliability of the engine and I agree with others that the resale on an EAB RV-12 is lower. But I really admired the ability to work in the engine compartment with the UL Power engine.
 
constant speed on a 12

Personally I think a constant speed would be a great improvement on a 12 like it is on any plane. It would not be a LSA but I expect about a 300' take off and 1600 fpm climb and a top speed of around 130 kts. I have played with different pitches from climb to cruise on my fixed pitch and have seen similar numbers at the extremes. A constant speed would insure you always had the magic 5200 rpm + at high manifold pressure to avoid detonation.
 
Personally I think a constant speed would be a great improvement on a 12 like it is on any plane.

CS prop is definitely not an improvement on any airplane. Depends on the airplane and weight. CS props are heavy. The bigger the plane, the less weight penalty there is. Airplanes toward the light and slow side do not benefit from a CS prop and they may even be detrimental. You don't see the experimental Super Cub guys who value weight and performance converting to CS props. Just one example.
 
CS prop is definitely not an improvement on any airplane. .

CS or fixed, just like nose or tail wheel or prime or not, is an opinion. I equate a fixed prop to driving a standard transmission car in just one gear. It works but not optimum for all situations. Just my opinion with over 500 hours in RVs for each way. I'm building my 7 with a CS and I think using one on a 12 would expand the capabilities of an already great little plane.
 
CS or fixed, just like nose or tail wheel or prime or not, is an opinion. I equate a fixed prop to driving a standard transmission car in just one gear. It works but not optimum for all situations. Just my opinion with over 500 hours in RVs for each way. I'm building my 7 with a CS and I think using one on a 12 would expand the capabilities of an already great little plane.

I think he meant "CS prop is not an improvement on just any airplane."
 
Personally I think a constant speed would be a great improvement on a 12 like it is on any plane. It would not be a LSA but I expect about a 300' take off and 1600 fpm climb and a top speed of around 130 kts. I have played with different pitches from climb to cruise on my fixed pitch and have seen similar numbers at the extremes. A constant speed would insure you always had the magic 5200 rpm + at high manifold pressure to avoid detonation.

I can attest that you do not need a CS prop to get those numbers. If you use a UL350iS and a WW GA-UL350-2B prop and pitch accordingly, you can be off the ground in 300’, climb between 1200-1700 fpm depending on weight and do 136-138 KTAS in level flight at 7500’ (with wheel pants and gear leg fairings...)

While I like the idea of a CS prop, I agree with Mel that there isn’t much value achieved for the cost.

As for resale, a topic that has been discussed ad-nausea on this forum, I’ve already been offered a very good price for my E-AB RV12 (I passed, as I still need my little bird for right now), but it was definitely contrary to the context that “E-AB is worth less than E-LSA”.
 
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No one has ever shown that there is a real value difference between the same aircraft model built as EAB vs. ELSA. There are advantages and disadvantages for each. It's simple a matter of a different prospective audience.
 
Thanks for replies on subject of CS on RV-12.

I got the idea from hangar neighbor who has Katana experience with 912 and CS. He showed me how easy it would be to convert, engine has pad for regulator and is CS ready except for prop, which has not been ID'ed. I don't know what the Katana is turning.

Just an experimenter thinking, Ive done crazier things than this. Will probably never happen, have a number of hoops to jump through yet for certification.
I will end up owner of this airplane, is done deal.

And am moving it to Minnesota later, have husband-wife ceremony coming up with friend from HS school days from 65 years ago. She's as crazy as am I at this age. :)
 
I’ve had the chance to fly quite a few Rotax powered LSA-class airplanes in the past few years, and Vern in the low and slow regime, I prefer a light CS prop over a fixed pitch, if for no other reason than you don’t have to worry about RPM when maneuvering. But that’s trivial compared to the ability to use the full range of the airplane - from climber to speedster.

I can think specifically about the Kitfox’s - flown them both ways, and when someone is handing out keys, I always grab the one with the Airmaster prop.

The caveat here is that I am not paying for them - so yes, cost is a definite consideration the buyer needs to think about. But as a pilot....interesting idea!

As for the ELSA vs. EAB, I think that BasicMed has changed the landscape on that considerably.
 
As for the ELSA vs. EAB, I think that BasicMed has changed the landscape on that considerably.

In the context of the RV-12 at least, I don't think it really matters, since a sport pilot can fly an E-AB or E-LSA RV-12, as long as they both meet the performance requirements of light sport. The only real difference between the two (in regards to resale to a second owner at least), is the ability to do the condition inspection. For E-LSA a second owner can take teh course and be able to do it. For E-AB, he will have to get an A&P (or the original builder, if they are willing) to do it.

Basic med has likely pulled some people away from light sport though.
 
In the context of the RV-12 at least, I don't think it really matters, since a sport pilot can fly an E-AB or E-LSA RV-12, as long as they both meet the performance requirements of light sport. The only real difference between the two (in regards to resale to a second owner at least), is the ability to do the condition inspection. For E-LSA a second owner can take teh course and be able to do it. For E-AB, he will have to get an A&P (or the original builder, if they are willing) to do it.

Basic med has likely pulled some people away from light sport though.

You?re right about all that Scott - my intent was to point it that with BasicMed, it doesn?t make any difference if. You keep an airplane within the LSA parameters or not - heck I can fly my jet on BasicMed if I wanted to!

So where it used to be really important to keep an LSA in that category, it doesn?t really matter now, as just about anyone that can fog a mirror can get a BasicMed sign off.
 
I can attest that you do not need a CS prop to get those numbers. If you use a UL350iS and a WW GA-UL350-2B prop and pitch accordingly, you can be off the ground in 300’, climb between 1200-1700 fpm depending on weight and do 136-138 KTAS in level flight at 7500’ (with wheel pants and gear leg fairings...)

While I like the idea of a CS prop, I agree with Mel that there isn’t much value achieved for the cost.

As for resale, a topic that has been discussed ad-nausea on this forum, I’ve already been offered a very good price for my E-AB RV12 (I passed, as I still need my little bird for right now), but it was definitely contrary to the context that “E-AB is worth less than E-LSA”.

How close is 136 KTAS at 7500' to Vne ???? at or over? Potential for wing flutter? I think most people here know that rongawer's E-AB build is an exceptional high performance RV-12 build with a lot of goodies in it that are quite desireable. Not all E-AB's are built or designed equally. If Ron keeps it as long as needed to build his other RV, while commuting in the RV-12 almost daily, he may have 1000 hrs on the tach meter and frame, when it finally goes up for sale. I've no idea how buyers prorate the price of a plane based on hours on tach and frame, and motor. I'm not familiar with rebuild process or potential of the UL-350IS, or if it's even possible.

The basic Rotax 912 series of motor is a whole different ballgame. It's Jet ski/ Personal Watercraft/ Snowmobile design/ mfg techniques, adapted to an airframe, with a crank that is pressed together inside of the big end of the connecting rods. No idea how you even measure tolerances at 2000 hrs, since you can't get the connecting rods off to insert plastigauge to even get a tolerance or gap reading, unlike conventional connecting rods in the automobile gas and diesel engine industry.
 
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You?re right about all that Scott - my intent was to point it that with BasicMed, it doesn?t make any difference if. You keep an airplane within the LSA parameters or not - heck I can fly my jet on BasicMed if I wanted to!

So where it used to be really important to keep an LSA in that category, it doesn?t really matter now, as just about anyone that can fog a mirror can get a BasicMed sign off.

Gotta

I wasn't thinking in that context because the conversation seemed to be related to resale value.
Doing a modification to an S-LSA compliant RV-12 (whether it be E-LSA or E-AB), that made it not comply with LSA requirements could have a negative impact on resale value, because the moment that mod is made, the airplane can never be flown by a Sport Pilot. I.E., it can never go backwards. Even if the mod. was reversed. Whether anyone would know is a whole different discussion........
 
You?re right about all that Scott - my intent was to point it that with BasicMed, it doesn?t make any difference if. You keep an airplane within the LSA parameters or not - heck I can fly my jet on BasicMed if I wanted to!

So where it used to be really important to keep an LSA in that category, it doesn?t really matter now, as just about anyone that can fog a mirror can get a BasicMed sign off.

I just got Basic Med, good for 4 years.

The required on line course is a good exercise too. Did the AOPA version.
 
Doing a modification to an S-LSA compliant RV-12 (whether it be E-LSA or E-AB), that made it not comply with LSA requirements could have a negative impact on resale value, because the moment that mod is made, the airplane can never be flown by a Sport Pilot. I.E., it can never go backwards. Even if the mod. was reversed. Whether anyone would know is a whole different discussion........

Keep in mind that a modification on an E-LSA that made it not comply with LSA parameters would not only "could never be flown by a sport pilot", it could never be flown at all by anybody. Once that mod happened, the Airworthiness Certificate would become invalid and there is no path to reinstate it.
 
Keep in mind that a modification on an E-LSA that made it not comply with LSA parameters would not only "could never be flown by a sport pilot", it could never be flown at all by anybody. Once that mod happened, the Airworthiness Certificate would become invalid and there is no path to reinstate it.

Yup
I figured the thread had drifted far enough from the center line as it was so wasn't going to go even farther with the nitty gritty.
 
How close is 136 KTAS at 7500' to Vne ???? at or over? Potential for wing flutter? I think most people here know that rongawer's E-AB build is an exceptional high performance RV-12 build with a lot of goodies in it that are quite desireable. Not all E-AB's are built or designed equally. If Ron keeps it as long as needed to build his other RV, while commuting in the RV-12 almost daily, he may have 1000 hrs on the tach meter and frame, when it finally goes up for sale. I've no idea how buyers prorate the price of a plane based on hours on tach and frame, and motor. I'm not familiar with rebuild process or potential of the UL-350IS, or if it's even possible.

The basic Rotax 912 series of motor is a whole different ballgame. It's Jet ski/ Personal Watercraft/ Snowmobile design/ mfg techniques, adapted to an airframe, with a crank that is pressed together inside of the big end of the connecting rods. No idea how you even measure tolerances at 2000 hrs, since you can't get the connecting rods off to insert plastigauge to even get a tolerance or gap reading, unlike conventional connecting rods in the automobile gas and diesel engine industry.

At 7500', Vne is based on KIAS, so the 136KTAS I referred to is below Vne, at around 117KIAS or so. The ride is smooth and stable and no discernible difference in flight characteristics from say, 120 KTAS.

This is off-thread, but since you posed the question...
A UL350iS is a very simple and well designed engine, and therefore an easy overhaul. You can either buy the parts and do it yourself, or have one of the UL shops to do it for you. It can be completely disassembled fairly quickly. In fact, my engine, I purchased used with 19 hours on it, but it had sat for a few years and I was concerned about it's condition internally, so bought a full set of gaskets, seals and crush washers, completely disassembled the engine, inspected (found it to be in new condition) and reassembled it on a Saturday. It's pretty simple with only a few "special" tools needed, which can either be improvised yourself or purchased from Wick's aircraft. (or possibly borrowed).
 
I just got Basic Med, good for 4 years.

The required on line course is a good exercise too. Did the AOPA version.

Anyone can weigh in if my understanding is incorrect, but the 4 year interval is for receiving the endorsement from a physician. One is still required to take the on line course every 24 months to maintain their Basic Med certification.
 
Anyone can weigh in if my understanding is incorrect, but the 4 year interval is for receiving the endorsement from a physician. One is still required to take the on line course every 24 months to maintain their Basic Med certification.

This is correct!
 
Anyone can weigh in if my understanding is incorrect, but the 4 year interval is for receiving the endorsement from a physician. One is still required to take the on line course every 24 months to maintain their Basic Med certification.

True....and a lot easier than a 3rd class medical.
 
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