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RV-12 vs RV-9

W

WVM

Well Known Member
Hi,

I am currently in the process of selecting which RV model is right for me. This process takes already 9 months... and I want to start building. Because it concerns both the RV12 and RV9, I thought that it fitted best in the general discussion.

My interest in building an RV started by watching a member from our aero club going home with his Europa on a trailer. Quickly I noticed that this is probably not the best plane to build. I checked several other brands, but always come back to VANS.

The RV12 was the best choice if I wanted to have the removable wings and being able to fly MOGAS. I am from the heart of Europe and AVGAS is rather expensive over here. The ROTAX engine was meeting this MOGAS requirement.

But then I started to dig a bit deeper into the other models. Generally under the influence of other RV builders in my neighborhood. One of them told me that he is able to fly much more fuel efficient with his Lycoming then with the Rotax. This is the reason that I tend to go for the RV9(a) with the IO-320-B1AC2 (160 HP) from Superior.

The thing that seems to be difficult to get reliable information about is the fuel consumption. Most pilots tell me that I should expect a fuel consumption of about 23 liter (6.08 gallons) at 2300 RPM per hour on a IO-320. Some tell me that it should be 15% less on the Superior over the Lycoming. The Europa owner told me that he flies at about 16 liters (4,23 USG) of MOGAS at 5000 RPM. Rotax suggests 20 liters (5,28USG) at 5000 RPM in their graphs. What are your experiences concerning fuel consumption on these engines? What could I expect on both?

Second concern is the speed. We commonly operate from shorter (+/- 2000 ft) runways, sometimes grass strips. My flight instructor told me once: The more power usually the better. Not that you always want to use it, but if you need it, it is there for you to use. That is a concern I have on the Rotax in the RV12. Purely looking at the performance on the VANS website, it shouldn't be a problem to operate the RV12, but some RV owners told me that you easily could get bored with the 100 HP engine from Rotax. The Rotax owner on the other hand told me that he also cruises at 115 Kts with his Europa at 5000 RPM. A RV9A owner told me that he generally cruises at 125 Kts at 2300 RPM. If this is true the difference of 10 Kts seems not to be that big to be honest.

What are your experiences on the fuel consumption and cruise speed related to both?

Many thanks!
 
The other question you need to ask is what kind of trips you plan to fly. Do you just fly around the area sight-seeing or do you plan to make long trips? If so, how far, and how high, do you need to fly? The RV-12 is perhaps the best Vans for sight-seeing due to the seat/wing location - the visibility is amazing. I'm told the RV-9(A) is preferred by Vans' own employees for trips. Choices...
 
RV-12: local flying, occasional trips, less windy conditions.

RV-9: Longer trips, heavier pax, more windy conditions. Tailwheel option :)

Short fields: RV-12 with a ground-adjust prop can be adjusted to give more RPM and power on climb. RV-9 with CS is best, but higher cost and operating cost.

Fuel burn: The 912S will burn about 5 gal/hr at WOT, + or - based on density altitude and prop pitch. Lots of performance data on the -9 with various engines. There won't be a big difference between them, except that the -9 is faster. The 912S needs premium mogas, most Lycomings / Lyclones can use regular mogas.

Removable wings: -12 only.

I'd see if you can use an in-flight adjustable prop on the 912S (more common in Europe, not the same as constant speed), and that would be a winner. Example: in the US, the CTSW has a fixed pitch prop and -6 flaps, WOT cruise about 115kt. Europe can get the adjustable pitch prop and -12 flaps, cruise about 135kt.

TODR
 
I've worked building both of them - in many ways they are quite different machines.

My incentive to build the RV-12 was initially the removable wings - I couldn't find a hangar. Later, the Light Sport/No FAA Medical option - probably not a factor in Europe - became important. With the recent ruckus over sleep apnia, I'm glad I went in that direction.

Still, even while building the RV-12, I thought if the FAA broadens the Drivers License Medical to bigger airplanes, I'd probably go with an RV-9A with its bigger engine. As mentioned - more horsepower is nice to have.

Now, I have flown my RV-12 for about 8 months - 135 flights into 26 different airports - long and short, paved and grass. About 30% local flying and about 70% cross-country. It is a very nice x-c airplane - no problems whatsoever. I've considered taking it on 3000 nm trips and would have no qualms about doing so. In fact, looking forward to it. I fly to Eastern Washington from Seattle across the mountains - I climb very quickly and easily to 9500 ft, with my wife, bags, and full fuel.

No more RV-9A in my dreams.

My experience has been the performance numbers are very conservative - I like that. I can cruise faster than the book, and I seem to be getting much better fuel consumption. I have been figuring the 20 gals fuel made it a 3 hour airplane - keeping 1 hour reserve. I now really figure it is a 4 hour airplane with the same 1 hour reserve. I'm getting much closer to 4 gph than 5 gph, and I spend a lot of time analyzing my flights.

I can't get to Gross Weight! With me (210 lbs), my wife (110 lbs), fuel fuel (120 lbs) and max cargo (50 lbs) - I'm 85 lbs below the Max Weight. Try that in a Skycatcher! Most of the time, I'm 185 lbs below Max Wt.

As far as takeoff performance - well all I can say is the -12 is a very snappy airplane. I'm sure I could make a very decent take-off on half power. If I open the throttle at all slowly, I'm flying by the time I get it opened all the way. Those 100 ponies combined with this very efficient airframe do an amazing job!

The visibility is sensational - it's one of the best features of this airplane. I love to sight-see and take hundreds of pictures - you can't find a better visibility airplane. Period.

Bottom Line: I love my RV-12. And, it's earned my praise.

As far as choices - no one to check with other than Mr. Van himself. He commutes to the Aurora plant from his N. Plains home, and obviously has his pick of the litter. His choice - his RV-12.

Bob Bogash
RV-12
N737G
 
AllThumbs said:
The other question you need to ask is what kind of trips you plan to fly. Do you just fly around the area sight-seeing or do you plan to make long trips? If so, how far, and how high, do you need to fly? The RV-12 is perhaps the best Vans for sight-seeing due to the seat/wing location - the visibility is amazing. I'm told the RV-9(A) is preferred by Vans' own employees for trips. Choices...
Click to expand...

They are indeed both different planes. The RV12 is primary build with the E-LSA option in mind. I don't really mind about that; but thanks to that it is much more fuel efficient, and that is what interests me. Still I am also listening to other builders, how tell me that I could grow out the RV12. To give you an idea, this is what I calculated:

- RV9A: 22 liters x 2,5 euro/liter (AVGAS) = 55 euro/hour at 125 Kts (230 km/h)
- Rotax in Europa: 16 liters x 1,6 euro/liter (MOGAS) = 24 euro/hour at 115 Kts (213 km/h)

If this is true I would be able to do more than double as much flight time with for the same money (fuel only!). This sounds a bit to good to be true to me. Therefore I want to do a reality check.
 
the_other_dougreeves said:
RV-12: local flying, occasional trips, less windy conditions.

RV-9: Longer trips, heavier pax, more windy conditions. Tailwheel option :)

Short fields: RV-12 with a ground-adjust prop can be adjusted to give more RPM and power on climb. RV-9 with CS is best, but higher cost and operating cost.

Fuel burn: The 912S will burn about 5 gal/hr at WOT, + or - based on density altitude and prop pitch. Lots of performance data on the -9 with various engines. There won't be a big difference between them, except that the -9 is faster. The 912S needs premium mogas, most Lycomings / Lyclones can use regular mogas.

Removable wings: -12 only.

I'd see if you can use an in-flight adjustable prop on the 912S (more common in Europe, not the same as constant speed), and that would be a winner. Example: in the US, the CTSW has a fixed pitch prop and -6 flaps, WOT cruise about 115kt. Europe can get the adjustable pitch prop and -12 flaps, cruise about 135kt.

TODR
Click to expand...

I am very interested in data on the RV9 with an IO-320. Do you have any data on them related to cruising speed and fuel consumption?

About the MOGAS on Lycomings. I know a mechanic with loads of experience on Lycoming engines. He told me that it is not a good idea to fly them on MOGAS. They immediately see when you did during maintenance, especially on the cylinder heads.
 
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NASA515 said:
I've worked building both of them - in many ways they are quite different machines.

My incentive to build the RV-12 was initially the removable wings - I couldn't find a hangar. Later, the Light Sport/No FAA Medical option - probably not a factor in Europe - became important. With the recent ruckus over sleep apnia, I'm glad I went in that direction.

Still, even while building the RV-12, I thought if the FAA broadens the Drivers License Medical to bigger airplanes, I'd probably go with an RV-9A with its bigger engine. As mentioned - more horsepower is nice to have.

Now, I have flown my RV-12 for about 8 months - 135 flights into 26 different airports - long and short, paved and grass. About 30% local flying and about 70% cross-country. It is a very nice x-c airplane - no problems whatsoever. I've considered taking it on 3000 nm trips and would have no qualms about doing so. In fact, looking forward to it. I fly to Eastern Washington from Seattle across the mountains - I climb very quickly and easily to 9500 ft, with my wife, bags, and full fuel.

No more RV-9A in my dreams.

My experience has been the performance numbers are very conservative - I like that. I can cruise faster than the book, and I seem to be getting much better fuel consumption. I have been figuring the 20 gals fuel made it a 3 hour airplane - keeping 1 hour reserve. I now really figure it is a 4 hour airplane with the same 1 hour reserve. I'm getting much closer to 4 gph than 5 gph, and I spend a lot of time analyzing my flights.

I can't get to Gross Weight! With me (210 lbs), my wife (110 lbs), fuel fuel (120 lbs) and max cargo (50 lbs) - I'm 85 lbs below the Max Weight. Try that in a Skycatcher! Most of the time, I'm 185 lbs below Max Wt.

As far as takeoff performance - well all I can say is the -12 is a very snappy airplane. I'm sure I could make a very decent take-off on half power. If I open the throttle at all slowly, I'm flying by the time I get it opened all the way. Those 100 ponies combined with this very efficient airframe do an amazing job!

The visibility is sensational - it's one of the best features of this airplane. I love to sight-see and take hundreds of pictures - you can't find a better visibility airplane. Period.

Bottom Line: I love my RV-12. And, it's earned my praise.

As far as choices - no one to check with other than Mr. Van himself. He commutes to the Aurora plant from his N. Plains home, and obviously has his pick of the litter. His choice - his RV-12.

Bob Bogash
RV-12
N737G
Click to expand...

Always nice to get information from someone that owns an RV12.

Related to loving the RV12... I never had the chance to see one except on picture and video. Last weekend I had the chance to see a RANS 19S. Someone told me that the RV12 is very similar to the 19S. To be honest with you, and purely on the looks, I really didn't like the 19S at all. It looked like a cheap toy. :D I am now very surprised to see an RV12 in real life. They are not yet that common in Europe, but someone pointed me to a flying one nearby. I really hope that the RV12 is different!

Do you have a lot of experience with removing the wings? Generally people tell me that it is a nice feature, but not really designed to do so after every flight. Based on VANS information I think it is more with the idea to store it during winter in a garage. What is your opinion on this?

If you have a fuel burn close to 4 gallons; what is your cruise speed? At what RPM are you running the engine at that moment? An ex Rotax owner told me that as long as you stay below 5000 RPM, it is pretty reasonable. Go over it and the fuel consumptions goes up to the sky, even much higher that an regular Lycoming consumes.
 
RV-9 perfomance

The 9 performance is exactly as Van has indicated including all speeds and performance take off and landings. I have a RV-9A with about 500 hours with the o-320 and a CS prop. It has a carb and mags. I generally cruise at around 140 knots ground speed at about 7 gph, 2450 rpm and 19-20" manifold pressure, about 55% power. I think that is about as low as you can go for typical flying without fuel injection, LOP and cruising above 10,000'. But I can go over 160 knots if I want to burn the fuel and the climb rate is usually 1500-1700 fpm with well over 2000 fpm solo when cold. It is a great X-country plane.

After just visiting a 12 project, with the kit design and pulled rivets, I believe the basic 12 airframe could be completed in a third the time of the 7 or 9 so build time is another consideration. Also you can build a basic VFR 9 more cheaply if you want since you can use analog instruments and a used engine rather than the new Rotax and glass.
 
The visibility on the -12 is exceptional. And its handling is excellent. If you don't need the higher speed of the -9, the -12 is a very nice aircraft. Quicker to build, too.

Dave
 
WVM said:
I am very interested in data on the RV9 with an IO-320. Do you have any data on them related to cruising speed and fuel consumption?

About the MOGAS on Lycomings. I know a mechanic with loads of experience on Lycoming engines. He told me that it is not a good idea to fly them on MOGAS. They immediately see when you did during maintenance, especially on the cylinder heads.
Click to expand...

Have burned Reg car gas in 0-320 lyc for years and if anything, less problems. But, I have 0-320 with 7.5 - 1 comp pistons @ 150 hp. No lead fouling of plugs or oil. Also I never fly above 8-9 thousand ft. Hot weather has never affected my engine. Cylinders extremely clean. I generally run from 8 to 9 gph --rich down low and slightly leaned at higher altitudes. Not hung upon LOP or ROP. But then I don't believe everything I hear.;)
 
Something else to consider, if you're going to build, is the build time. The RV-12 will build faster than the RV-9 and can be built pretty much without help, where-as the RV-9 will require some help in places. Folks who have experience building both could provide more info on this.

Regards, Jim
 
mark schoening said:
Have burned Reg car gas in 0-320 lyc for years and if anything, less problems. But, I have 0-320 with 7.5 - 1 comp pistons @ 150 hp. No lead fouling of plugs or oil. Also I never fly above 8-9 thousand ft. Hot weather has never affected my engine. Cylinders extremely clean. I generally run from 8 to 9 gph --rich down low and slightly leaned at higher altitudes. Not hung upon LOP or ROP. But then I don't believe everything I hear.;)
Click to expand...

I agree with you that you don't have to believe everything. That is why I greatly appreciate others opinions. My point is that it is now that I have to decide which RV to build and I have to do it with the information that is available. Fuel prices are really a concern in Europa, but I also don't what to focus too much on it, especially not if it will impact my joy of flying. But based on my earlier post with the comparison on the RV9A and the Europa, if it is only about 10 kts in differences, for about half the fuel price, then I would not mind going a bit slower. I just want to ensure that I don't have to keep the plane in the hangar, because there is a bit to much wind or because my friends are flying to a grass strip that is out of reach for the RV12.
 
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Jim T said:
Something else to consider, if you're going to build, is the build time. The RV-12 will build faster than the RV-9 and can be built pretty much without help, where-as the RV-9 will require some help in places. Folks who have experience building both could provide more info on this.

Regards, Jim
Click to expand...

I understand that the build time is less because of the rivet type used on the RV12. It is another debate but aircraft engineers told me that these pop rivets are of less quality then the regular AN rivets on the other RVs. It is not that the frame will fall apart, but over time it can become an issue. Knowing that the RV12 is still a very young air frame design, it is hard to say what the future will bring on this. I have asked VANS if I could use AN rivets, and they told me that it would be "Impractical and probably impossible.". Purely on esthetics I don't really liked the rivet hats on the RANS 19S. I am waiting to see a RV12 to make an opinion on it.
 
First, the -12 is a great airplane! Other than being limited to two seats, it out performs a Cessna 172 and that says a LOT!

One of my EAA chapter member has a Europa and he does remove the wings to take it home for the annual condition inspection. Other than that, the wings stay on all the time.

Have put over 510 hours on my RV-9, the first 275 hours with a 135 HP O-290 and the remaining with a 180+ HP O-360.

The -9 performs as Van's states and flies like, well, it flies like an RV. Very similar to the -12.

I can cruise at 150 to 155 Kts while burning around 7.1 GPH. With the standard 7.5:1 compression, you can run premium auto fuel. (I realize you don't have ethanol in your auto fuel, which is good!)

The biggest issue is the cost and time to build. They can be equal or you can go overboard on the -9, it is all up to you. The -9 is more of blank canvas whereas the -12 is pretty much "paint by numbers".

Best of luck with your choice. Whatever you pick, you can't go wrong.
 
A 2000' runway? I WISH I had that!!! RV12 operating out of a 1260 foot home grass strip with no problems, just careful. Before I started operating here, I had the prop pitched for cruise, wheel pants on, and was getting 122kt at 5450 rpm at just less than 5GPH (US gallons) of auto premium fuel. When I started using this strip, I have temporarily taken off the wheel pants (lost 3 to 4 kt) and repitched the prop just slightly for better takeoff. Still getting 116 to 118 kts cruise at same fuel consumption. For a really short strip I recommend adding the AOA.
 
Rv-9A Performance

Here is the thread where I have been tracking Perf #'s coming out of my annual.

I have been known to mix in some mogas and if anything she is a hair faster.

The -9A will also loiter at 130KTAS on 5 gallons per hour.

The 12 is great plane, too. Hard to lose here.

From Rosie: Another related thread here.
 
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decide your purpose, time and budget

I built/fly an RV9A w/ an IO-320 160 HP. I got to custome panel, engine etc to what i wanted. Lop of 155 knots true at 8,000 burning just over 7 gph. Can throttle back to 50% down lower and see 125 true on just less than 6 gph for leisurely sightseeing. Performance numbers across board match Van's advertised.

Also building 12. Ready to fly assembly time under 800 hours, mostly single person construction with basic tools vice special dimpling & bucking etc. I've put wings on/off several with help of one person in under 10 minutes each time. Watch YouTube video and believe it IS that easy. I believe Van's numbers which means cruise diff much more than 10 knots.

Do you want, need and can you afford higher performance and gross at a tradeoff of longer build time, higher fuel cost and hangar or tie down cost as long as you own plane?

Either plane great but definitely more difference than 10 knots.
Good luck!
 
N941WR said:
First, the -12 is a great airplane! Other than being limited to two seats, it out performs a Cessna 172 and that says a LOT!

One of my EAA chapter member has a Europa and he does remove the wings to take it home for the annual condition inspection. Other than that, the wings stay on all the time.

Have put over 510 hours on my RV-9, the first 275 hours with a 135 HP O-290 and the remaining with a 180+ HP O-360.

The -9 performs as Van's states and flies like, well, it flies like an RV. Very similar to the -12.

I can cruise at 150 to 155 Kts while burning around 7.1 GPH. With the standard 7.5:1 compression, you can run premium auto fuel. (I realize you don't have ethanol in your auto fuel, which is good!)

The biggest issue is the cost and time to build. They can be equal or you can go overboard on the -9, it is all up to you. The -9 is more of blank canvas whereas the -12 is pretty much "paint by numbers".

Best of luck with your choice. Whatever you pick, you can't go wrong.
Click to expand...

Please note that we do have ethanol in our auto fuel. This is the main concern for owners to keep on using AVGAS. Even while there is a big difference in price: a gallon of AVGAS costs about 12,89 USD, while a gallon of auto fuel is about 8,34 USD.

The difficult thing is that there is generally none in, but fuel suppliers are allowed to add a percentage of ethanol if they want. Sometimes to do. To be on the safe side you will need to test each time you refuel and this is what keeps most of the owners away from doing so. On the other hand there are owners that do use it all the time. In general without problems. It depends on how far you are willing to go...
 
AF_Alan said:
I built/fly an RV9A w/ an IO-320 160 HP. I got to custome panel, engine etc to what i wanted. Lop of 155 knots true at 8,000 burning just over 7 gph. Can throttle back to 50% down lower and see 125 true on just less than 6 gph for leisurely sightseeing. Performance numbers across board match Van's advertised.

Also building 12. Ready to fly assembly time under 800 hours, mostly single person construction with basic tools vice special dimpling & bucking etc. I've put wings on/off several with help of one person in under 10 minutes each time. Watch YouTube video and believe it IS that easy. I believe Van's numbers which means cruise diff much more than 10 knots.

Do you want, need and can you afford higher performance and gross at a tradeoff of longer build time, higher fuel cost and hangar or tie down cost as long as you own plane?

Either plane great but definitely more difference than 10 knots.
Good luck!
Click to expand...

The 6 gallons at 50% power and 125 Kts comes close to what a RV9A owner told me last weekend.

Related to the wings. I have seen the video and it is easy. The only point is, was this designed with the idea to do it after every flight or only from time to time. The airports that I operate from have only yearly hangar contracts. You basically have to remove them after each flight or never remove them at all.

Concerning the building costs. I calculated, based on invoices from another builder, that the RV9 would cost about 14000 USD more, if you put the same instruments and options in it as the RV12 kit. It is true that you are pretty much forced to use a new Rotax on the RV12. In a RV9 you can easily put a second hand Lycoming, which are easier to find. If you do so the RV9 becomes cheaper to build than the RV12. The RV12 is a big winner on the building time.
 
WVM said:
Purely on esthetics I don't really liked the rivet hats on the RANS 19S. I am waiting to see a RV12 to make an opinion on it.
Click to expand...

For what it's worth, I have built several aluminum aircraft with flush pulled rivets where dome head rivets were provided in the kit. Other than a little extra time required for countersinking and dimpling, it was no problem at all and well worth the effort. One of these aircraft has almost 2,000 hours on it and has been around the country several times, showing no problems with the rivets at all.
 
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Mel said:
For what it's worth, I have built several aluminum aircraft with flush pulled rivets where dome head rivets were provided in the kit. Other than a little extra time required for countersinking and dimpling, it was no problem at all and well worth the effort. One of these aircraft has almost 2,000 hours on it and has been around the country several times, showing no problems with the rivets at all.
Click to expand...

This is what VANS told me about that:

Impractical and probably impossible. Nobody considered bucking address during design, because blind rivets were specified from the very first. Many rivet tails are just not reachable.

Rivet holes are pre-punched to blind rivet size (usually 1/8") and bucking rivets that big in .016 and.020 skins is going to get pretty ugly...

An aircraft engineer that I know, who is also a designer of home builds, is clear: "that type of rivet should no be used on aircrafts..." This is probably a bit too radical to my opinion.
 
I said I used pulled rivets. That is another term for blind rivets; not solid rivets.

There is no problem using blind rivets on aircraft as long as the aircraft is designed for blind rivets. The RV-12 WAS designed for blind rivets.
There are many aluminum aircraft designed around blind rivets flying all over the world without problems.
 
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Mel said:
I said I used pulled rivets. That is another term for blind rivets; not solid rivets.

There is no problem using blind rivets on aircraft as long as the aircraft is designed for blind rivets. The RV-12 WAS designed for blind rivets.
Click to expand...

Ok, but what type of rivet is actually used in the RV12? Apparently the Cherry rivets are similar and designed for aircrafts: http://www.cherryaerospace.com/product/blindrivets.html
 
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The "Cherry N" rivets would be my choice for the RV-12. I have used them on a Moni Motorglider and a Zenith CH601HDS. As mentioned before, the CH601HDS has almost 2,000 hrs and has flown around the US several times since 1995 showing absolutely no rivet problems.
 
Whatever you decide upon Vim, please keep us informed as you progress through the kit. And congratulations, you certainly have the right middle name! ;)
 
Since I have the keys to both in my pocket, I thought I might comment. I have been flying the 9A for about six years; the 12 for a year and a half. They really fly quite similarly, in my opinion. The 9 rides a little better in rough air, the speeds can be found on Van's website--they are accurate. Fuel costs do favor the 12, although the 9 can do similar speeds at similar fuel flows, throttled back. Cost comes into play with the difference between 100LL and mogas. Going places at some distance, the 9 has it. Shorter trips and just flying for the fun of it, I give the nod to the 12. I actually like the view from the 12 better, and it can be more comfortable, but that is very subjective. There is no doubt you can build the 12 quicker, and probably for less money, with similar panels. Very close call here for many mission types, and you can't go wrong with either. GREAT flying planes!

BTW, I am going flying for the fun of it today. It will be in the 12.

Bob
 
Keep in mind that just because the RV-12 was designed to be built using blind rivets, it doesn't mean that just any blind rivet you chose would be a proper choice.
A rivet with at least the same strength properties as the original should be used.
 
videobobk said:
Since I have the keys to both in my pocket, I thought I might comment. I have been flying the 9A for about six years; the 12 for a year and a half. They really fly quite similarly, in my opinion. The 9 rides a little better in rough air, the speeds can be found on Van's website--they are accurate. Fuel costs do favor the 12, although the 9 can do similar speeds at similar fuel flows, throttled back. Cost comes into play with the difference between 100LL and mogas. Going places at some distance, the 9 has it. Shorter trips and just flying for the fun of it, I give the nod to the 12. I actually like the view from the 12 better, and it can be more comfortable, but that is very subjective. There is no doubt you can build the 12 quicker, and probably for less money, with similar panels. Very close call here for many mission types, and you can't go wrong with either. GREAT flying planes!

BTW, I am going flying for the fun of it today. It will be in the 12.

Bob
Click to expand...

Thanks for your input! Can you give a comparison on the fuel usage in relation to travel speed for both types?
 
Wim,
Pretty much any side by side RV, regardless of the engine installed, can fly along side an RV-12 and burn very close to the same amount of fuel at the same speed. I do it regularly with my 180 HP RV-6A (I do a lot of local sight seeing flights throttled way back). Sure, we could have a conversation about the pumping losses on a larger displacement engine throttled way back, compared to the Rotax running at an efficient power setting... but in reality the effect is very small. Drag is drag and HP is HP. An RV-12 and an RV-9A moving through the air at the same speed will have a very similar drag flat plate area. It takes a specific amount of HP to pull that amount of flat plate area though the air. It takes a specific amount of fuel to produce that amount of HP.

My point is, a lot of other factors will have more influence on how the fuel flow of an RV-9 would compare to an RV-12 (at the same speed) than what engine you chose. A few examples.... what prop is installed, the finish quality of the airplane, alignment of fairings and attention to drag reduction, etc.).

Considering all of the other issues that are important in this decision process, looking at which airplane has the lowest fuel flow at a given speed should be way down the priorities list.
 
videobobk said:
Since I have the keys to both in my pocket, I thought I might comment. I have been flying the 9A for about six years; the 12 for a year and a half. They really fly quite similarly, in my opinion. The 9 rides a little better in rough air, the speeds can be found on Van's website--they are accurate. Fuel costs do favor the 12, although the 9 can do similar speeds at similar fuel flows, throttled back. Cost comes into play with the difference between 100LL and mogas. Going places at some distance, the 9 has it. Shorter trips and just flying for the fun of it, I give the nod to the 12. I actually like the view from the 12 better, and it can be more comfortable, but that is very subjective. There is no doubt you can build the 12 quicker, and probably for less money, with similar panels. Very close call here for many mission types, and you can't go wrong with either. GREAT flying planes!

BTW, I am going flying for the fun of it today. It will be in the 12.

Bob
Click to expand...

Bob I agree with you and your comparisons for the 2 planes. It really comes down to your missions, if speed is a factor the it is a no brainier. I have a good friend with a very sweet 9 and both fly very close. I think my 12 has a little more room for pilot and passenger. I am 6'4" and even thought the 9 states 40 - 43 inch and the 12 states 44 - 41 1/2 inch for the width the configuration seams to have more room. Also the 12 is easier to get into due to the tip up canopy and where it hinges forward in the 12.

Once again like others have said you will not go wrong with the 9 or 12. You need to fly both of you get the chance. :)
 
Performance numbers

"If you have a fuel burn close to 4 gallons; what is your cruise speed? At what RPM are you running the engine at that moment? An ex Rotax owner told me that as long as you stay below 5000 RPM, it is pretty reasonable. Go over it and the fuel consumptions goes up to the sky, even much higher that an regular Lycoming consumes."


Flight late afternoon Dec. 24 (scouting for Santa....) RV-12

0S9 to KPWT 33.9nm

OAT = 35 deg F
No wheel pants
Estimated weight = 1080 lbs
Typical data point:

Alt = 3011 ft
TAS = 113.9 kts
RPM = 4875
FF = 4.1 GPH (USG)

The flight was:
Hobbs = 31 minutes.
Tach Time = 24 minutes

During the cruise portion, the:

RPM varied from 4284 to 5332 RPM
Altitude averaged 3000 ft
TAS varied 104.3 to 121.6 kts - average about 112 kts
FF varied 3.6 to 5.4 GPH - Average 4.4 GPH

Estimated fuel consumed = about 1.8 gals (USG.) This is a little shaky as it's coming off the float and started from a level just above the float's upper cutoff - but pretty close.

Prem. Mogas @ $3.40/USG = Fuel cost for flight approx $5.98. USD.

Estimated cost in my Toyota Tacoma - 49.2 stat. miles @ 24 mpg @ $3.14/USG (Regular gas) = $6.44 USD.

The RV-12 wins!

Bob Bogash
RV-12
N737G
 
Many, many thanks Bob! Great!

Now I also understand why you guys don't see fuel an major issue... only $3.40 per gallon! Here we pay $8,5 for a gallon regular gas. For AVGAS that would be $13.65 per gallon.
 
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Often times when building my -9A I wished I had went with the -12 for simplicity and less time building.

One thing that swayed me that I thought I would dislike about the -12 is that the fuel tank is located in the baggage compartment, effectively reducing the baggage area... Never seen one in person so can't say for sure if that is an issue, but that is one difference I didn't like.
 
WVM said:
Many, many thanks Bob! Great!

Now I also understand why you guys don't see fuel an major issue... only $3.40 per gallon! Here we pay $8,5 for a gallon regular gas. For AVGAS that would be $13.65 per gallon.
Click to expand...

I don't think any of us have implied fuel is not a major issue. Fuel cost is the primary reason I cruise around at low power settings.

What has been emphasized, is that you should not be choosing one model over the other based on fuel economy. They can both have nearly identical economy if flown at the same speed. If you fly an RV-9A at an average speed of 112 Kts, it will also average about 4.4 GPH fuel burn.
 
Choices.

Up to about six months ago I was flying my 9A with a Wilsch Diesel in it. It used about 18 l/hr of Avtur cruising about 115kt. Work out for your self what that would cost you. The aircraft was forced landed possibly due to water in the fuel and written off but I will rebuild it.

I now fly my RV4 and the fuel bills were a real shock compared with the 9 but you need to compare build costs and equate in time. Whatever the difference in cost to build is can probably buy a lot of fuel.

Both the 9 and 12 are good aircraft (note no S, aircraft is a word that is both singular and plural).

Making a choice is always difficult I struggled between the 6 and the 4 for months but at some point you need to make that decision or walk away.
 
Fuel tank location

I personally don't like the fuel tank location either. Van put it there, I think, primarily to cater to the removable wings. Also possibly some CG and wing structure considerations.

I don't have a safety concern - which some people do - there are a lot of airplanes that have fuselage fuel - some right over your head or over your feet behind the dash! One of my RV-9A pals is an ex KC-135 driver, and when he mentions it, I point out all the fuselage fuel he carried around for years.....

My problem is primarily maintenance - a lot of jobs require removing the fuel tank, which means draining the fuel system and disconnecting (and then reconnecting) the fuel feed and return lines.

I also covet that baggage space which is pretty meager to start with. I wish the tank - if in the fuselage - were a different shape - say flat and shorter covering the whole baggage area where you could put stuff on top of it - or long and rectangular behind the pilot seats (someone has made that mod - check the archives.)

Really, I wish there were - say - two 15 gal tanks - one in each wing (especially the leading edge.) That would extend my range significantly, and use some of the available Useful Load that is currently being wasted (as noted in my first post.) However, the RV-12 is nose heavy as it is (when empty) and wing leading edge tanks would introduce all sorts of C.G. complications.

As Scott is fond of always reminding everyone, airplanes are full of design compromises - none are perfect. Plus, there are all these arm-chair engineers "helping" the designer. I'm a real engineer making it all the worse!

Bob Bogash
RV-12
N737G
 
rvbuilder2002 said:
I don't think any of us have implied fuel is not a major issue. Fuel cost is the primary reason I cruise around at low power settings.

What has been emphasized, is that you should not be choosing one model over the other based on fuel economy. They can both have nearly identical economy if flown at the same speed. If you fly an RV-9A at an average speed of 112 Kts, it will also average about 4.4 GPH fuel burn.
Click to expand...

I understand that. But the other way around, and personally, if fuel prices here would be around $3.4 a gallon... I would probably go the RV9 and don't even think about how far the throttle was open... :D
 
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For the -12, With the easy split rear bulkhead and floor plate mod (see the RV12 Modifications Sticky Thread, top of the page) you may never need to remove the tank again. I installed an ADSB receiver and antenna behind the bulkhead without needing to remove the tank and i'm 200#. Also installed the landing gear beefup mod without taking the tank out.

Two guys went to OSH in the plane carrying bags and a fan for the dorm room and it all fit. You can put very lightweight stuff on top of the tank, towels, jackets. A flat-floor tank sounds nice but you have to be able to get at the tunnel underneath - fuel pump and pushrods are there. And the tank would have to be beefier to have bags and stuff thrown on top of it. So a totally different design would have been needed.
 
Wim
When people in US write about long cross country flights, I wonder if Europeans would ever in reality fly such distances?
Makes the 12 possibly even more suited to Europe given the visibility from the cabin that is spoken of.
 
NASA515 said:
"If you have a fuel burn close to 4 gallons; what is your cruise speed? At what RPM are you running the engine at that moment? An ex Rotax owner told me that as long as you stay below 5000 RPM, it is pretty reasonable. Go over it and the fuel consumptions goes up to the sky, even much higher that an regular Lycoming consumes."


Flight late afternoon Dec. 24 (scouting for Santa....) RV-12

0S9 to KPWT 33.9nm

OAT = 35 deg F
No wheel pants
Estimated weight = 1080 lbs
Typical data point:

Alt = 3011 ft
TAS = 113.9 kts
RPM = 4875
FF = 4.1 GPH (USG)

The flight was:
Hobbs = 31 minutes.
Tach Time = 24 minutes

During the cruise portion, the:

RPM varied from 4284 to 5332 RPM
Altitude averaged 3000 ft
TAS varied 104.3 to 121.6 kts - average about 112 kts
FF varied 3.6 to 5.4 GPH - Average 4.4 GPH

Estimated fuel consumed = about 1.8 gals (USG.) This is a little shaky as it's coming off the float and started from a level just above the float's upper cutoff - but pretty close.

Prem. Mogas @ $3.40/USG = Fuel cost for flight approx $5.98. USD.

Estimated cost in my Toyota Tacoma - 49.2 stat. miles @ 24 mpg @ $3.14/USG (Regular gas) = $6.44 USD.

The RV-12 wins!

Bob Bogash
RV-12
N737G
Click to expand...

My CT with a 912ULS will burn about 4.7 on a 5200 RPM X-country. My neighbors -12 burned 4.3 on the same trip, probably because he had to throttle back so I could keep up! I wonder if the person stating consumption goes up a lot if you go over 5000 RPM maybe had his prop set incorrectly?
 
Fuel tank removal

Yes, you're right Bill. I also did the MLG beef-up without removing the tank (but, as you know, that was contrary to the SB recommendations or instructions.) I've also changed the ADAHRS three times. And I plan to install a stiffener soon to make the ADAHRS support structure less flexible. All without removing the tank.

But the bulkhead/floorplate mods do not constitute the "build per plans" requirement of USA E-LSA airplanes. Van has the mods in his own airplane - really the factory should make them a part of the Plans. Unless you make the post CofA mods, you're stuck with a lot of tank removals.

I wonder what the S-LSA airplanes have? And can those S-LSA owners and their mechanics even do the mods legally, or are they stuck with the tank removals for the life of th airplane?

Bob Bogash
RV-12
N737G
 
NASA515 said:
I wonder what the S-LSA airplanes have? And can those S-LSA owners and their mechanics even do the mods legally, or are they stuck with the tank removals for the life of th airplane?
Bob Bogash
RV-12
N737G
Click to expand...

Unfortunately SLSA guys are stuck with how it came unless they can get written approval from the manufacturer.
Operating Limitations, paragraph "(6) Noncompliance with these operating limitations will render the airworthiness certificate invalid. Any change, alteration. or repair not in accordance with the manufacturer's instruction and approval will render the airworthiness certificate invalid, and the owner of the aircraft must apply for a new airworthiness certificate under the provisions of 14 CFR, 21.191 with the appropriate operating limitations before further flight."
 
I have no experience building either aircraft, but I would choose the RV 12 just because I can save lot of time building and be flying sooner. That would be worth the effort.
 
rjtjrt said:
Wim
When people in US write about long cross country flights, I wonder if Europeans would ever in reality fly such distances?
Makes the 12 possibly even more suited to Europe given the visibility from the cabin that is spoken of.
Click to expand...
No surprise that most of the S-LSAs are European-produced aircraft....
 
the_other_dougreeves said:
No surprise that most of the S-LSAs are European-produced aircraft....
Click to expand...

I honestly don't think this is the reason. Fuel prices are. Here we see more and more schools trade in their Cessna's and replace them by SportCruisers, Tecnams, ... The main reason is operating and fuel cost. If we could we would also fly greater distances. A gallon of AVGAS costs $13.65. An this is rather a low price over here, it has been over $16 per gallon only a few months ago.
 
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Kram said:
I have no experience building either aircraft, but I would choose the RV 12 just because I can save lot of time building and be flying sooner. That would be worth the effort.
Click to expand...
Building is part of the journey. On the other hand I hear that the difference in building time between both should not be over exaggerated. If you strictly stay to the plans without modifications, it would probably be a lot faster to build an RV12. But this is what VANS is also saying about the RV9. What costs time is all the customizations, fancy avionics, extra's and finish.
 
I started with the emp kit of an RV-9 (still have it and may finish the whole thing one day). Now I'm working on the 12.

I really like the 9. I wanted the long legs and fast cruising speeds the 9 affords.

Having said that there is no comparison with the 9 and the 12 when it comes to building; especially if this is your first time building. Everything is laid out in the 12 plans/kit. The drawings and plans are one in the 12. In the 9 you bounce back and forth between the plans and the drawings which are separate documents.

The pull rivets are much faster than the squeeze rivets. Very little deburring of parts is required in the 12. There is also very little up-drilling of holes in the 12. In the 9, you need to deburr but you also need to take the small holes in just about everything and turn them into larger holes. All of this is time consuming in the 9 (7, 6, etc.) builds.

There is more flexibility in how you build your 9 and what you put in it, but this is also more time consuming. The 12 comes with wiring harnesses, wiring diagrams, panel hook up instructions, flight test procedures (Production Acceptance Procedures), maintenance manual, flight training supplement manual, and of course the Pilot's Operating Handbook. see the latest versions at http://www.vansaircraft.com/public/service-rv12.htm

Bob
 
All, thank you for your input. I think it will be the RV-9... One reason is the "limited" power of the Rotax. The Rotax is probably a good engine, but the more part and the higher the speed, the more likely it may fail. I think this are wise words from someone with +30 years of engine experience. But the main reason is the rivets. There are too many that I know that have strong doubts about using pop rivets for airplanes. They asked me to get the exact type of rivet that is used, to be 100% sure. Can anyone provide this info please?
 
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WVM said:
All, thank you for your input. I think it will be the RV-9... One reason is the "limited" power of the Rotax. The Rotax is probably a good engine, but the more part and the higher the speed, the more likely it may fail. I think this are wise words from someone with +30 years of engine experience. But the main reason is the rivets. There are too many that I know that have strong doubts about using pop rivets for airplanes. They asked me to get the exact type of rivet that is used, to be 100% sure. Can anyone provide this info please?
Click to expand...

Go for the -9 by all means. It is a great aircraft, but not directly comparable to the RV-12 in terms of performance or`mission'. The RV-12 is a different aircraft and is designed around the Rotax. The power is not `limited' for this airframe, nor is it more likely to fail than a Lycoming. The RV-12 (and many other LSA's) are designed to use pulled rivets, so stop worrying. The pulled rivets are mainly LP-4-3. There are also a lot of standard rivets in this airframe. Vans know what they are doing when it comes to aircraft design. IMHO you are focussing on relatively unimportant details when your decision should be based on other parameters. If fuel efficiency is the main driver as per your initial posts, then both will perform well. Choose your mission (as our US friends like to say), then choose your plane.
 
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