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  #1  
Old 04-08-2019, 07:53 PM
David-aviator David-aviator is offline
 
Join Date: Feb 2005
Location: Chesterfield, Missouri
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Default RV-12 with CS prop?

Just an update.
Iíve 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
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  #2  
Old 04-08-2019, 08:37 PM
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Mel Mel is offline
 
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Location: Dallas area
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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.
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North Texas (8TA5)
RV-6 Flying since 1993, 172hp O-320, 3-Blade Catto (since 2003)Sold
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  #3  
Old 04-09-2019, 11:19 AM
NinerBikes NinerBikes is offline
 
Join Date: Dec 2018
Location: Granada Hills
Posts: 129
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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.

Last edited by NinerBikes : 04-09-2019 at 11:25 AM.
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  #4  
Old 04-09-2019, 04:08 PM
pilotyoung pilotyoung is offline
 
Join Date: Jan 2018
Location: Birmingham, AL
Posts: 102
Default 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.
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  #5  
Old 04-09-2019, 05:20 PM
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scottmillhouse scottmillhouse is offline
 
Join Date: Apr 2007
Location: Madison, AL
Posts: 266
Default 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.
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  #6  
Old 04-09-2019, 05:32 PM
luddite42 luddite42 is offline
 
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Location: USA
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Quote:
Originally Posted by scottmillhouse View Post
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.
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  #7  
Old 04-09-2019, 06:17 PM
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scottmillhouse scottmillhouse is offline
 
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Location: Madison, AL
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Quote:
Originally Posted by luddite42 View Post
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.
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  #8  
Old 04-10-2019, 07:16 PM
AeroDog AeroDog is offline
 
Join Date: Aug 2011
Location: New London, NC (near Charlotte), Boulder, CO
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Quote:
Originally Posted by scottmillhouse View Post
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."
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  #9  
Old 04-10-2019, 08:54 PM
rongawer rongawer is offline
 
Join Date: Dec 2007
Location: Brentwood, CA
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Quote:
Originally Posted by scottmillhouse View Post
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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Last edited by rongawer : 04-10-2019 at 09:31 PM.
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  #10  
Old 04-10-2019, 09:13 PM
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Mel Mel is offline
 
Join Date: Mar 2005
Location: Dallas area
Posts: 10,271
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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.
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Mel Asberry..DAR since last century
A&P/EAA Tech Counselor/Flight Advisor/Nat'l Test Pilot School
Specializing in Amateur-Built and Light-Sport Aircraft
<rvmel(at)icloud.com>
North Texas (8TA5)
RV-6 Flying since 1993, 172hp O-320, 3-Blade Catto (since 2003)Sold
Legend Cub purchased 12/2017
FRIEND of the RV-1
Eagle's Nest Mentor
Recipient of Wright Brothers "Master Pilot" Award
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