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RV-9 LSA Discussion

David-aviator

Well Known Member
I was in the middle of replying to this thread and it simply disappeared, gone, no can locate....

Anyway, here's the gist of what my thoughts are on the subject.

Set Operating Limitations to LSA standards and it is an LSA airplane. Isn't that what CubCrafters has done with the Carbon Cub - and with FAA blessing?

THE LIGHT SPORT CATEGORY LIMITS THIS AIRCRAFT TO:
900 lb empty weight and 1320 lb gross weight on wheels.
Maximum continuous speed of 138 miles per hour.
Maximum takeoff power limited to five minutes.
Maximum continuous power limited to 80 HP after five minutes.

The engine is a Lycoming 0340 rated at 180HP but only for take and climb, not for cruise. You must pull the power back to 80HP as per operating limitations so as to not exceed max speed to 138 mph.

Seems like the same could be done with any amituer build airplane, simply write it into the program letter and make it a part of the operating limitations. Of course all the other limits of LSA, like 2 seats, FP prop, stall speed, etc would have to be complied with.

There are a ton of airplanes on the market that meet LSA limits. Why not a modified RV-9? The precedent has been set at Cub Crafters. Rather than design an airplane to max LSA limits, simply set operating limits so as to not exceed those limits.
 
Weight

Mostly because most RV-9s weigh in around 1,000 lbs empty. The LSA Max at 1320 limits you to one 180 lb pilot and 20 gal of gas.
 
Actually there are already a number of RV9's that are registered EAB-(which the builders claim are LSA compliant). The SLSA from Cub Crafters is a bit different of a story than EAB-(that meet LSA compliance) or even ELSA's. It can be done, but I think pretty much it's frowned on because you can't really make a good LSA out of it just purely due to empty weight as say compared to something like the ELSA (that you could build as EAB) that Van's already offers - that being the marvelous RV-12!

I think that since Van's now offers such a good lineup of airplanes, one should just look at purchasing the airplane designed for the task. It's kind of like if you want an RV9 that does a bunch of Aerobatics, then just get a -7. If you want a -9 that is an LSA, then just get a -12. If you want an RV-9 that has 4 seats, then get an RV-10....you get the point. :)

Just my 2 cents as usual.

Cheers,
Stein

PS: This link : http://www.liteplane.com/home.html is usually what gets people going on this entire topic. Note his sales of "RV9/A ELSA's"....I won't get involved in that one!
 
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Save even more by not insuring.

You can have any amount of discussion about building an RV-9 as an LSA.

Since the aircraft can never be certificated as an LSA, the only problem arises when you encounter a problem like trying to get an insurance settlement following an accident.
You can fly a "Rocket" as an LSA if you want to. But, it is up to you to show LSA compliance when challenged.

BTW, there is no maximum empty weight for LSA. That limit is only for SLSA (Light-Sport Category).
 
LSA stall speed maximum is 45 kts (54 mph). Ours stalls at 51 mph indicated. So you're probably close but OK on that. I'll bet it would cruise at way more than 120 kts, even with 100hp, unless you artificially dirtied it up.

I'd hate the intentional ineffeciency.
 
Remember...

The 45 kt. max stall speed for LSA is "CLEAN" stall speed. Stall speed with flaps doesn't count.
 
LSA stall speed maximum is 45 kts (54 mph). Ours stalls at 51 mph indicated. So you're probably close but OK on that. I'll bet it would cruise at way more than 120 kts, even with 100hp, unless you artificially dirtied it up.

I'd hate the intentional ineffeciency.

vortex generators should help both speeds get lower..
 
Never saw the original post, so I am wondering, Why? Why try to make an RV-9 LSA? Was there a builder who lost medical while building, etc? Or was the intent to make it more "marketable" if they needed to sell later?

As an aside, the Arion Lightning started out as a 120HP E-AB aircraft that would do about 155 knots maxed out. They added some wing tips, left off the gear fairings, limited cruise RPM on the Jabiru and BAM! LSA compliant and available from the factory as a completed aircraft. I guess it can be done...
 
Would you like some beachfront property....

....in Kansas?

This house of cards will more likely than not come tumbling down.

Best,
 
There's a DAR in central Fl that has built two 9s for the purpose of flying as LSA. Basically he builds as normal amateur built and keeps the parameters within LSA reg. He had one at Sebring, O-235 and 2 blade wood prop with a very sparse panel--I think it was 930 empty.( I know--it's marginal useful load) He says he even had a letter from Vans himself stating that the aircraft met the lsa parameters. Just to be clear--these are NOT LSA aircraft but they fall within the metrics to fly with a light sport license.
 
I too was left wondering what happened to the original thread...

I'm not sure if this is the same 'guy' that flybuddy is referring to...but the RV-9 and RV-9A "LSA's" being exhibited at Sebring this year were built by 4 retired firemen. They've been building 1 plane per year (sez the guy...), they moved the redline on the tach (to meet the speed requirement), they added vortex generators on the wing to beat the stall speed, and they are known real well by the FSDO guys' (sez the guy...), the implication being that this is an entirely legal arrangement.

FWIW I thought the build quality was a bit weak (even to my untrained eye...), the planes were being hawked like it was a carnival of sorts, and there were many 'winks' and unfinished sentences when I asked Q's like 'What's the endurance of the a/c as an LSA?' ('Well...you know, it kinda depends on how much gas you put in the tanks (wink, wink...) and, you know, what you do is what you do...')

The whole affair left the two of us feeling like we'd picked up some scum on our clothes from the encounter. If the way in which Mitch Lock presents the RV-12 and represents Vans is at one end of the 'This is how it should be done in the LSA World' continuum - and he is - then this was W-A-Y at the opposite end of what I think flying should be about.

Jack
 
the RV-9 and RV-9A "LSA's" being exhibited at Sebring this year were built by 4 retired firemen. They've been building 1 plane per year (sez the guy...), they moved the redline on the tach (to meet the speed requirement), they added vortex generators on the wing to beat the stall speed, and they are known real well by the FSDO guys' (sez the guy...), the implication being that this is an entirely legal arrangement.

Are they building these airplanes for "sale"? What category are the aircraft certificated in? SLSA? ELSA? EAB?
SLSA would be the only "available" route for this type of operation, and that takes a pretty large investment the show ASTM compliance for aircraft, engine, and operation.
 
I thought they were licensing the airplanes as EAB, but were building them to comply with all of the LSA limitations by limiting the redline, limiting the gross weight, adding vortex generators, etc. Then, they can be flown by sport pilots, just like a Cub, or an early model Ercoupe can be flown by sport pilots. Is this correct?
 
My point was...

I thought they were licensing the airplanes as EAB, but were building them to comply with all of the LSA limitations by limiting the redline, limiting the gross weight, adding vortex generators, etc. Then, they can be flown by sport pilots, just like a Cub, or an early model Ercoupe can be flown by sport pilots. Is this correct?
1/ They are claiming to have built 4 airplanes in 4 years. That sounds like they are building them for sale. You can't do that under EAB.

2/ If you buy one of these airplanes, and operate it as a sport pilot, it will be YOUR responsibility to show that it is LSA compliant.

Operation is at your own risk!

3/ I have quite a bit of experience with Light-Sport Category and Experimental Light-Sport aircraft and I don't believe that there's any practical way to bring the RV-9 design into LSA compliance.

And the designer agrees!
 
I agree 100% with all of your points Mel. (and the designers too!) I was just asking because some folks have been suggesting the airplanes were licensed as LSA. I can't see how that would be possible, so was trying to confirm if they are licensed EAB.

But, if a legitimate builder wanted to build an RV-9, and limit the GW to 1320, and comply with the other LSA requirements, would there be any reason not to issue the EAB airworthiness certificate?
 
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Mel, I'm just speculating based on the discussion at the booth...but with 4 ex-firemen builders involved and building 1 a/c per year, I can imagine they rotate the official registration ownership and take the position 'Hey, built one 4 years ago, sold it and decided to build another one.' They were being pitched as E-AB completed but available to be flown under the LSA rules given the mods made to them (sez the guy).

Oily, distasteful experience.

Jack
 
RV-9A LSA

I understand that the RV9A can be qualified as LSA. Interested in feedback from those that have gone down this path.

Pat
 
There should be a lot of info already here------try using the search, and dont forget to set it to any date, not the default of one year.
 
listing less than Vans gross weight

From what I have been reading on this thread, I, the builder can pretty much set the max weight to whatever I want. I understand I may have to justify it to FAA or insurance company at some date.

My question is, could I set the weight for a -9 at 1320lbs even though Vans says 1600-1750? And yes, Im trying to find a loophole to build the -9 as an LSA. I would still have to deal with the speed, but if I painted it like the Piper 140 I saw the other day, speed wouldn't be an issue. It looked like they used a paint roller and house paint!
 
Yes, you can initially set your gross weight at 1320 lbs.
This would be the easiest part of trying to comply with LSA limitations. Other problems include max speed and clean stall speed.
 
speed would be the issue

Yes, you can initially set your gross weight at 1320 lbs.
This would be the easiest part of trying to comply with LSA limitations. Other problems include max speed and clean stall speed.

The clean stall speed appears to be ok for LSA. lsA requires 45 knots, the -9 says 44mph on Vans site. As for the speed, I may need to swipe the lancair speed brakes from my friend and mount them open at all times or some kind of air anchor!
 
The clean stall speed appears to be ok for LSA. LSA requires 45 knots, the -9 says 44mph on Vans site. As for the speed, I may need to swipe the Lancair speed brakes from my friend and mount them open at all times or some kind of air anchor!

I believe the 44 mph stall speed listed on Van's website is with full flaps.
 
51 mph

Correct. The LSA exact is 51mph clean. Depending on the engine in the -9, it is pretty close. Im not sure how the FAA would check, maybe it would involve an actual demonstration. Im looking for loopholes here or a way to make it possible. If I am the manufacture, maybe I can just test it and say it meets the requirements. It can't be that simple, but Im looking for anything I can to make it work.
 
Van has an LSA , it's an RV 12:)

Trying to squeeze a -9 into the LSA is a waste. I know a guy who did it here, and I just can't see the sense in it.
 
reason

David, I understand RV has an LSA. The 12 is a great plane. Im not here to argue about that. As for it being a waste or you seeing a reason for it, you don't have to. As for me, there is a good reason. I want a -9 because I live in Colorado and in my opinion, the high altitude performance in the 9 is better than the 12. I currently can not qualify for the medical needed for the 9. There is a chance that the FAA will pull their head out of their orifice and include planes like the 9 as acceptable for LSA.

So you see David, there doesn't have to be a reason that is acceptable to you. The Vans is an experimental airplane. I had one of my engineers look at the structure of the 12 to see if I could mount a Rotex 914, and he said it would be difficult, but possible. I suppose I could build a 12 now, sell it and then build a 9 when the rules change, but I don't have that much time. If I can build the plane I want now to meet the LSA requirements then modify it later, that is a better option for me. That is why for me, there is a good reason to explore the possibilities.
 
There is a chance that the FAA will pull their head out of their orifice and include planes like the 9 as acceptable for LSA.
I suspect they'll do that about as quickly as some builders and pilots stop turning a blind eye to common sense.
 
goes both ways

I suspect they'll do that about as quickly as some builders and pilots stop turning a blind eye to common sense.

Maybe when the FAA starts using common sense and make regulations based on facts and statistics, some of us won't have to look for ways to get around those regulations. As I said, you don't have to think it is a good idea or concern yourself if I am using common sense or not. It is up to me to decide if it is a good idea or not.
 
Risk Perception

I love it when Navy guys talk about taking too much risk.

Honestly.

Those men have commited to taking the most riskiest flying known to man. way, way WAY over the risk thresholds of any of the civilian sectors.

When I was an officer in the Army I have had friends of mine shoot live rounds past me at less then an few feet by accident and then run past and say "oops sorry dude".

The Military for those reasons gets taught to be extremely risk averse but thats because they take HUGE risks. Any Navy pilot that tells you their lifestyle is safer is just kidding themselves. Thats why it takes balls of steel to do it right, because if you don't, your dead!

I know a guy that flew from London to Capetown with 2200 pounds in an RV 7 and he put the CoG as far back as he could. I am not even going to tell you how far back it actually was. He flew through an African thunderstorm on the way back. Not that I think thats a good idea but he did. The RV was OK.

If you really want to understand risk perception listen to this. Fly up really high with a friend in an RV 10 then in the middle of the flight just open up the door and jump out, but so you don't get hurt grab a big piece of cloth and tie some little ropes to the edges and just hold on to the little ropes on the way down and you should be OK.

There are people in this forum that thing that doing this is far safer than flying an RV7 at 1900 lbs.

Sky diving, sure, an extra 100 lbs, your mad.

Your living inside of a risk paradigm.

Its not physics, its not best practices its a way of thinking and most people will argue the merrits of their paradigm.

The reality of risk is that its a concept.

The events brought about by action, that is different. That is consequence.

And that is determined by God, who here would have thought that an RV7 with 2200 pounds, going mostly at 185 KTAS ,with the CoG all the way back that goes through a thunderstorm would be OK.

Perception is what this post is about and I think all of it is healthy conversation that allows people to view other perspectives. If it makes anyone think twice about anything both in an adventurous way or a conservative way then I think this forum is functioning well.

... but then again, thats just my perception
 
Army pilots too

Let's acknowledge some naval aviators have ovaries of titanium! :)
Agree on the Navy and Air Force, but don't forget the Army pilots. My son is an AH 64 Apache pilot. I would suggest flying the Apache might be as exciting as any of the RVs. The hellfire missles help with the thrill factor!
 
thanks for link


Thanks Pierre. I did a search earlier to see if this had been discussed, but somehow missed that thread. After reading all the posts, I am encouraged that it has been discussed and done by other builders. As for those posting about how dirty it was and they felt soiled because someone was trying to get away with something, that's an OK position to take.

For me, it looks like it may be possible to get around a rule that is in the process of being changed - hopefully, without having to build 2 planes. For me it is the chance to be flying again in a plane that I consider safer because of the high altitudes where I live. If I could put a larger engine on the 12, I would do that. I could put a climb prop on and I am sure that would help. I admit - it is a way to get around a regulation written years ago that I don't believe is based on facts or statistics. If there were accident reports showing Sport Pilot licensed pilots were crashing because of medical issues, or if I felt I was not medically fit to fly, I would continue to fly right seat and not be concerned what plane I built.

With all the posts now and from this link, I think this has been discussed about as far as it needs to be. Thanks to all those who offered information and their feelings about a -9 that meets the requirements to be flown by a sport pilot.
 
For me, it looks like it may be possible to get around a rule that is in the process of being changed - hopefully, without having to build 2 planes.

First I would like to make it clear that no rule is "in the process of being changed."

At best, what AOPA and EAA are asking for is an "exemption" for certain aircraft to be flown by pilots without a current medical. Even it this does happen, which I hope it does, it will not be a rule change per se.
 
At best, what AOPA and EAA are asking for is an "exemption" for certain aircraft to be flown by pilots without a current medical. Even it this does happen, which I hope it does, it will not be a rule change per se.

Just for the educational content, the medical exemption is now written into our new rule set, and prior to that being released we will have an exemption instrument in place. Yes it happened down under, thanks to the SAAA with support from AOPA Australia.

I think you willbe far happier with your RV-9 under this system.:)
 
change

Just for the educational content, the medical exemption is now written into our new rule set, and prior to that being released we will have an exemption instrument in place. Yes it happened down under, thanks to the SAAA with support from AOPA Australia.

I think you willbe far happier with your RV-9 under this system.:)

That is great and gives me hope it can happen here too. Maybe it will give more data for the FAA to consider. (lol)

I completely agree that I would be happiest with the -9, and that is what I will probably do. I may build it and do what is necessary for it to be LSA compliant, or just play the FAA game and pass the medical.

I understand what has been proposed and what the chances are - as much as you can understand government. I have spoken to the FAA, EAA, AOPA, and several certified flight physicians. It isn't as simple as it could be. The easiest would be to allow up to 180 or 200hp airplanes to be flown with a Sport Pilots license under the same rules they currently have. That is too simple.

My understanding of the proposed changes are to fly one of the planes included, I would have to get a class 3, get my pilots license, let the medical expire, and I would be allowed to continue to fly that plane under sport pilots rules. The added step of having to get the class 3 is ridiculous to me. If I would be allowed to fly the plane with an expired medical, why did I need it in the first place?

Just from the former pilots I know, eliminating the class 3 requirement for 180 or 200hp and under planes will give aviation the biggest increase since after WWII. That may be the problem. The FAA knows that and I don't think they are interested in growing general aviation. That is sad.
 
Just from the former pilots I know, eliminating the class 3 requirement for 180 or 200hp and under planes will give aviation the biggest increase since after WWII. That may be the problem. The FAA knows that and I don't think they are interested in growing general aviation. That is sad.

I do not have data to support my view but I doubt that the 3rd class medical is even a minor impediment to MOST new pilots. I suspect that the high cost is a bigger barrier to the few people who have an interest in the first place.
 
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I do not have data to support my view but I doubt that the 3rd class medical is even a minor impediment to new MOST pilots. I suspect that the high cost is a bigger barrier to the few people who have an interest in the first place.

Until the price of flying comes down, I don't think there is much chance of younger people even taking flying lessons. The price isn't coming down anytime that I can see so the only other thing is to get pilots who were forced out of the left seat back into the air.

When I was raising my kids, I didn't have enough money to keep flying. Now that we are empty nesters and I have progressed in my career, we have the extra money to spend on flying. I say we because my wife wants to fly too. We could just buy a plane, but building one has always been my dream. For business, we have the company plane we take. I just want to fly around and have fun!

I know at least 4 guys that have their own plane, but can't legally fly it because they can't renew their medical. Im not saying they don't fly, just that their medical has expired. I know several other former pilots that are afraid to try to pass their medical so they won't be disqualified for a Sport pilot license. Just ask the guys hanging around the airport talking rather than flying. I think the number is larger than you think. I have no data other than the pilots and former pilots i know, but just those guys probably doubles the starts last year!
 
How to take 9A gw up? Not the builder!

I believe the 44 mph stall speed listed on Van's website is with full flaps.

Mel, If I bought a 9a EAB Light Sport compliance what do I do to get it back to regular 9a gross wt 1730 ? I know however once it’s gw is back up it can’t come down again. Thanks
 
Mel, If I bought a 9a EAB Light Sport compliance what do I do to get it back to regular 9a gross wt 1730 ? I know however once it’s gw is back up it can’t come down again. Thanks

To change the gross weight, you will need to place the aircraft back into Phase I and complete testing at the new gross weight.

Your operating limitations cover this procedure.
 
893 lb 9a

It is possible to build a 9a to meet the 900lb max empty weight. I built my 9a to meet the Recreation Aviation Australia spec's which has the same MTOW and Stall as LSA. The aircraft weighed in empty at 893lb with a 0-235 C2C Lycoming and Kato prop. the light weight gives the 9a a flapped stall of 35 kts and 38 kts clean. You would never lighten up an existing aircraft to get it down to anywhere near 900 lbs but if you keep focused on the goal of building one to meet that weight it is possible as long as you stay focused and don't even deviate for 1/2 a oz. Do your research well and stay focused. As an example there is 41 lb difference between the lightest 0-235 and the heaviest.
Be warned...… the lightest components are usually the most expensive!!!!
The most important thing....STAY FOCUSED!!!!!...STAY FOCUSED!!!!!....STAY FOCUSED!!!!!!!!!!!!!! And you can do it.

Did I mention STAY FOCUSED!!!!:eek: :D

Bob
 
Van has an LSA , it's an RV 12:)

Trying to squeeze a -9 into the LSA is a waste. I know a guy who did it here, and I just can't see the sense in it.

That’s your opinion David not mine!! How old are you mate somewhere around 50? I have not seen you for a couple of years so I may be a bit off?? I’m pushing 80 so when you get to my age and your class 3 is not available I bet your opinion will change!!

Barnacle Bob😘
 
It is possible to build a 9a to meet the 900lb max empty weight. I built my 9a to meet the Recreation Aviation Australia spec's which has the same MTOW and Stall as LSA. The aircraft weighed in empty at 893lb with a 0-235 C2C Lycoming and Kato prop. the light weight gives the 9a a flapped stall of 35 kts and 38 kts clean. You would never lighten up an existing aircraft to get it down to anywhere near 900 lbs but if you keep focused on the goal of building one to meet that weight it is possible as long as you stay focused and don't even deviate for 1/2 a oz. Do your research well and stay focused. As an example there is 41 lb difference between the lightest 0-235 and the heaviest.
Be warned...… the lightest components are usually the most expensive!!!!
The most important thing....STAY FOCUSED!!!!!...STAY FOCUSED!!!!!....STAY FOCUSED!!!!!!!!!!!!!! And you can do it.

Did I mention STAY FOCUSED!!!!:eek: :D

Bob


What did the O-235 C2C Lycoming weigh with engine mounts?

What other key items did you use or skip altogether?

No paint?

Glass EFIS?

No wheel pants or fueselage and pant fairings?
Carbon fiber cowling?
No interior?
Fiberglass bucket seats with air cushions for seats and backs?

I would think if one could afford it, using the Rotax 915IS, though expensive, would lose a LOT of weight, quickly, over a O-235? Or a Big Bore kit on a Rotax 912 ULS that bumps it to 120 HP, normally aspirated?

The devil is in the details, maybe share some of the big hitter details for putting a RV-9A on a Weight Watchers diet.
 
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ultralight 9a

What did the O-235 C2C Lycoming weigh with engine mounts?

What other key items did you use or skip altogether?

No paint?

Glass EFIS?

No wheel pants or fueselage and pant fairings?
Carbon fiber cowling?
No interior?
Fiberglass bucket seats with air cushions for seats and backs?

I would think if one could afford it, using the Rotax 915IS, though expensive, would lose a LOT of weight, quickly, over a O-235? Or a Big Bore kit on a Rotax 912 ULS that bumps it to 120 HP, normally aspirated?

The devil is in the details, maybe share some of the big hitter details for putting a RV-9A on a Weight Watchers diet.

Hi NB,

The 0-235 C2C as received (used) weighed in at 245 lb and after re-build and fitment of all the lightest bolt on's weighed in at 217 lb but that was not with engine mounts.

Most of the weight savings was in the interior and under the cowls so everything where possible in the aircraft was moved forward for COG.

This was a quick build kit but nothing was modified on the supplied build.

I studied the RV12 for ideas and cut 45% off the weight of the seats when I constructed them and fitted a D180 EFIS as part of that study.

Moved the battery mount over in line with the starter motor, this meant about 50% less cable was required and this as well as the low compression engine meant a smaller cable as well as a smaller battery could be used.

The cowls are standard fiberglass.

light paint was applied to 25% of the aircraft.

first up there was no wheel pants or intersection fairings fitted to the mains but with some further weight savings else where in the aircraft I was able to fit pants and fairings to the mains and still keep the weight under 900 lbs.

To give you all details of the weight saving build I would need to write a book. But basically never fit anything to the aircraft without studying it first, looking at the job it has to do and trim off all ballast on that piece before fitting even if you think it is not worth the micro weight saving!!

Always, SAFETY MUST COME FIRST!!!

The most important things.... Dedication and stay focused on the end product. Back when I first posted first flight with the weight of the aircraft ( April 2011) I had builders from all over the world wanting advise and guidance to build light but most had lost the plot before they were even half way through their build. this is why I keep saying STAY FOCUSED!!

I'm not too sure how you would go with COG with a Rotax….. may be longer engine mount and this would mean longer cowls etc and that means adding more weight to save weight. From memory the Lycoming 0-233 LSA engine which wasn't released when I built mine is about 5 lb lighter than my 0-235 C2C.

Bob
 
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Hi NB,

The 0-235 C2C as received (used) weighed in at 245 lb and after re-build and fitment of all the lightest bolt on's weighed in at 217 lb but that was not with engine mounts.

Most of the weight savings was in the interior and under the cowls so everything where possible in the aircraft was moved forward for COG.

This was a quick build kit but nothing was modified on the supplied build.

I studied the RV12 for ideas and cut 45% off the weight of the seats when I constructed them and fitted a D180 EFIS as part of that study.

Moved the battery mount over in line with the starter motor, this meant about 50% less cable was required and this as well as the low compression engine meant a smaller cable as well as a smaller battery could be used.

The cowls are standard fiberglass.

light paint was applied to 25% of the aircraft.

first up there was no wheel pants or intersection fairings fitted to the mains but with some further weight savings else where in the aircraft I was able to fit pants and fairings to the mains and still keep the weight under 900 lbs.

To give you all details of the weight saving build I would need to write a book. But basically never fit anything to the aircraft without studying it first, looking at the job it has to do and trim off all ballast on that piece before fitting even if you think it is not worth the micro weight saving!!

Always, SAFETY MUST COME FIRST!!!

The most important things.... Dedication and stay focused on the end product. Back when I first posted first flight with the weight of the aircraft ( April 2011) I had builders from all over the world wanting advise and guidance to build light but most had lost the plot before they were even half way through their build. this is why I keep saying STAY FOCUSED!!

I'm not too sure how you would go with COG with a Rotax….. may be longer engine mount and this would mean longer cowls etc and that means adding more weight to save weight. From memory the Lycoming 0-233 LSA engine which wasn't released when I built mine is about 5 lb lighter than my 0-235 C2C.

Bob

The Rotax 912 UL, fitted with a Zipper Big Bore kit should go about 122 # plus engine mounts, prop and such. Find a later model 912 UL built after 2007 and talk to Hal Stockman at Zipper Big Bore kits in Ely, NV, USA, and you could build a very light RV-9A, on a used block Rotax 912 UL. Saving 100# will make what HP you have available more useful.

Most RV-12's go 775 # with paint. A really skinny one with no paint and no interior might go 750#, and they start with a 95 HP Rotax 912 ULS motor, only 95 HP due to dual air filters instead of a single air filter. So I don't see under 900 # with 115 HP being much better or worse. It might be a 140 to 145 MPH bird.

Of course, if built with a 115 HP 914 Turbo, the 9-A will do much better at elevation, where it shines.

The RV-9 will, of course, have more drag than the RV-12, longer wings, and the CG is further aft. In a RV-12, you sit FORWARD of the wing Spars, your butt sits maybe 4 to 5" in front of the leading edge of the wing spars, due to the lightness of the engine.

Myself, I would love to see a RV9 built around a Rotax, 915IS Turbocharged motor making 141 HP. But as you said, the plane would need some sort of redesign, or maybe a RV-15 model or RV-16 model, to make it possible. I think that if it was the first turbocharged powerplant available from Van's, and capable of something a bit above utilitarian G load rating wise, so you don't exceed the "envelope" at 15k, it might fill a nice niche.

But don't quote me on it, Van's knows more than anyone else, what sells and what it's customers want. I am new to the game, and I'm not impressed with a motor that eats a quart of oil every 6 to 10 hour. A Rotax rarely does that, if at all, if run on Mogas and Full Synthetic motor oil. Or at least mine doesn't.
 
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No matter what engine you use different people have different opinions of engines. I've flown a lot of hours behind Rotax's and they are a great little engine but I have also flown behind Lycomings and they are my old favourite.

The Rotax is a performance engine that produces more horsepower pr cube than the Lycosauris and it also has the gearbox to help get more torque to the prop. the Lycoming was designed back in the 1940's (from memory mine is a 1956) and their idea back then to get more power was to bolt on a supercharger and increase the cubes. So what you do is up the performance of the Lycoming.

I stayed with the low comp pistons but I fitted P Mags (electronic ignition gives a better spark and timing= more power), Fitted a Rotec TBI (that gives better atomisation of fuel-air mixture= more power) 1 1/2" crossover performance exhaust system(=more power). While the "more power" may not add up to much it does improve the 0-235's performance.

I have 2 Cato props for the 9a, A climb prop and a cruise prop (it takes me about 15-20 minutes to change a prop).
The climb prop with 2 up and fuelled to keep it under 1320 lb MTOW it will climb out at 1000' a minute and cruise at 120 kts IAS @ 2450 RPM sipping 3.7 GPH of Mogas or avgas.
The cruise prop with the same load climbs out at 800' FPM cruises at 130 kts @2450 RPM sipping 3.8 GPH.

Because oil is cheap compared to engines I change the engine oil and filter every 25 hours. the engine now has just on 600 hrs on it but I never have to add oil between oil changes.

Bob
 
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