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Ironflight

Ironflight

VAF Moderator / Line Boy
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A few teaser pics….

F46366E3-8D22-42CD-B1A1-B312DED12AF1.jpg 026A6D94-0C22-40DC-A1AA-44A44E84B81A.jpg


It’s not often that you get to fly both the oldest and the newest airplane of a specific type - and they are the same plane!

I spent the day in Sebring, Florida with “Mr. Rotax” himself, Phil Lockwood. Phil unveiled his ongoing project, the RV-9A with a Rotax 915iS that was displayed at this year’s Airventure. I first saw the airplane and examined it in detail last spring, but was asked to keep it under my hat until its public unveiling. The airframe is Serial Number 1, loaned to Lockwood for the project by Vans, and while you’ll have to wait for a full review coming in Kitplanes in coming months, I can share first impressions with this group.

This a mature (and still maturing) engineering project that has produced a remarkable plane, capable of excellent speed and efficiency at altitude. It can easily bust through existing Vne, and that is something being worked - I won’t quote numbers to keep everyone involved happy (and myself out of trouble), but I will say that we were easily cruising in the mid-170’s (KTAS) at 12.5k Burning 7.4 gph of Swift 94 - and the airplane does even better higher up.

It is stable, and recently passed a major spin testing program - handles well, is as honest as any RV-9 I have flown, and frankly was delightful to fly. The long nose? It looked normal after a few hours with the plane - I hardly notice in anymore.

Lockwood is planning on producing a conversion kit - price TBD…not cheap, but when is performance ever cheap? Last week I flew homebuilt twin-engined flying boat that has a kit price of 1.5 million dollars….and they have several on order. There’s always someone that thinks it’s worth it to them! The Rotax -9 might be one of them to someone that wants a true altitude cruiser….

No….we’re not inverted! But those are RVGrins!
 

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Is the dorsal fin unique to this airframe? The whole vertical tail looks a bit different - maybe just proportions thrown off by the dorsal fin.

Tail is the same - just the dorsal was added (to account for the added sail area of the longer cowl).
 
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Ironflight said:
A few teaser pics….

View attachment 48720 View attachment 48722


It’s not often that you get to fly both the oldest and the newest airplane of a specific type - and they are the same plane!

I spent the day in Sebring, Florida with “Mr. Rotax” himself, Phil Lockwood. Phil unveiled his ongoing project, the RV-9A with a Rotax 915iS that was displayed at this year’s Airventure. I first saw the airplane and examined it in detail last spring, but was asked to keep it under my hat until its public unveiling. The airframe is Serial Number 1, loaned to Lockwood for the project by Vans, and while you’ll have to wait for a full review coming in Kitplanes in coming months, I can share first impressions with this group.

This a mature (and still maturing) engineering project that has produced a remarkable plane, capable of excellent speed and efficiency at altitude. It can easily bust through existing Vne, and that is something being worked - I won’t quote numbers to keep everyone involved happy (and myself out of trouble), but I will say that we were easily cruising in the mid-170’s (KTAS) at 12.5k Burning 7.4 gph of Swift 94 - and the airplane does even better higher up.

It is stable, and recently passed a major spin testing program - handles well, is as honest as any RV-9 I have flown, and frankly was delightful to fly. The long nose? It looked normal after a few hours with the plane - I hardly notice in anymore.

Lockwood is planning on producing a conversion kit - price TBD…not cheap, but when is performance ever cheap? Last week I flew homebuilt twin-engined flying boat that has a kit price of 1.5 million dollars….and they have several on order. There’s always someone that thinks it’s worth it to them! The Rotax -9 might be one of them to someone that wants a true altitude cruiser….

No….we’re not inverted! But those are RVGrins!
Click to expand...

I can't say I'm a Rotax guy but I do recognize the advantages. This does sounds promising.

Now what's happening with the Yamaha conversion? It could be a little more cost effective.

Tim
 
Ironflight said:
[...]The airframe is Serial Number 1, loaned to Lockwood for the project by Vans[...]
Click to expand...

I saw it at S&F this year but didn't realize that the airplane belonged to Vans. I find it interesting that they loaned the airplane and are allowing modification. I would imagine the kit may be able to be purchased through Van's down the line which be be a great endorsement for Lockwood.

I wonder if the cowl/engine mount will help with other engines.
 
Ironflight said:
. The airframe is Serial Number 1, loaned to Lockwood for the project by Vans
Click to expand...

For those wondering how it could be serial # 1 when it wasn’t the first RV-9 built at Van’s…. it is because it was the prototype RV-9 tail dragger.
It was converted to a 9A before it was shipped to Lockwood.
 
gfb said:
Any work being done to increase Vne with these mods?
Click to expand...

It's not just Vne, flutter is a consideration, especially at altitude. To simplify, Vne goes with IAS but flutter goes with TAS. One of my friends is a DER for structures and flutter, and when I tried to ask him a simple question about flutter, the answer was not simple at all!

Ground vibration testing is expensive but commonly used for determining flutter limits. Stick pulsing is not a very good way of determining flutter limits, but that's another story.

Some time back, Van's published numbers for a sailplane, showing different limiting speeds because of flutter speeds at altitude.

Also, Rotax engines have a number of components to be changed out on schedule, but then again, how many of us do the mags at 500 hours and pay attention to suggested life limits on hoses? And when I had the AirCam, with the Rotax engines, fuel additive was a fact of life to keep lead under control because it was less of a nuisance than autogas.

I'll admit, I'd love to have an extra 20 knots in my RV-9A when I make those occasional long X-C, but, then again, sitting in the cockpit with the autopilot handling the controls and waiting hours for the next waypoint...
 
The aircraft and for that matter the RV7 might be a great performer with the 916 Rotax. Same cruise numbers but a great takeoff performance.
 
There are well heeled concerns about flutter in this thread. I see where Kitfox is putting the Rotax 916is on their aircraft. There's no question their TAS will increase significantly, especially at altitude. That one really gets my attention because their flying flaperons are more susceptible to flutter excitation than a conventional aileron. Back in the early 90's the Avid Flyer and Kitfox (knock off of the Avid) aircraft had flaperon flutter issues and a honkin' counterbalance weight kit was released to address the issue.
 
Ed_Wischmeyer said:
It's not just Vne, flutter is a consideration, especially at altitude. To simplify, Vne goes with IAS but flutter goes with TAS. One of my friends is a DER for structures and flutter, and when I tried to ask him a simple question about flutter, the answer was not simple at all!
....
Some time back, Van's published numbers for a sailplane, showing different limiting speeds because of flutter speeds at altitude.
Click to expand...

The Vne speed covers all disciplines, i.e., loads, stress, flight controls, stability & control, propulsion, and flutter. There is not a 'Vne' and then another limit just for flutter. Vne is set by the designer such that the airplane as a whole is safe to fly up to that speed in calm air. It may be stated as IAS, TAS, or a combination of IAS and TAS as a function of altitude. Also, just because a designer sets Vne as a constant IAS doesn't mean they have not taken flutter into account. It means that they just set Vne in terms of a constant IAS number that ensures that flutter will not occur within the operating envelope of the airplane.

The conservative approach for flutter is to assume a constant TAS limit when the critical flutter mode(s) are either not known or not well understood. Some flutter modes have flutter speeds that follow a TAS line with increasing altitude. An example of these are the so-called "explosive" flutter modes, where there is a large decrease in aeroelastic damping for a small increase in airspeed. "Aeroelastic" damping is Structural Damping plus Aerodynamic Damping. Structural Damping is usually a constant, the value of which depends on the construction design and materials used in the structure.

Other flutter modes follow the so-called "half and half" speed line with increasing altitude, roughly midway between EAS (CAS/IAS for us non-Mach challenged RV's) and TAS. An example of these would be the so-called "hump" flutter modes, where there is a small decrease in aeroelastic damping for a large increase in airspeed. It is called a "hump" mode because it looks like a hump when plotted on an Airspeed vs Damping plot.

And some flutter modes follow more of an EAS line with increasing altitude.

BTW, the article you referred to is "Flying High and Fast".
 
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Good to see Van's and Lockwood teaming up to give builders a possible second engine choice given the Lycoming backlog.
 
I was down at Lockwood taking the Service & Maintenance courses from Dean when it completed testing that week. There were a LOT of smiling faces!!!
 
With a snout like that there will be a LOT of folks asking if there's a turbine under the hood!

After having the opportunity to operate some of the Rotax iS-series of engines I have to say they are making a positive impression on me. Seeing them almost explode into life on startup and then seeing the Lane A / Lane B control architecture working is quite impressive. Like many folks here I thought it would be difficult to get used to the much higher rev's these engines produce. Nope, that wasn't a factor at all - just push the throttle forward and go, keep the tach needle off the redline just like any other engine. It was almost too simple. OK, it was enjoyably simple.
 
EAA hosted a Webinar this week starring Phil Lockwood, who had some tidbits on the program:
  • Testing is very much still underway, with work being done towards being able to offer a full kit
  • 915/916 can do single-lever power with a CS prop and integration box from RS Flight Systems
  • Getting ~120hp in cruise in Eco-mode (lean-of-peak). 75% of a 160 HP Lycoming. Can do max continuous (135hp, aka 75% for a 180hp Normally-Aspirated engine) up to ~19,500'. Maximum altitude is 22,500', as higher will cause the turbo to over-speed.
  • US engines have 5 year, 2000hr factory warranty, includes major components, fusebox, ECU
  • They're currently using an early 915is, but are planning to swap it out with a 916is soon. Added performance will show up in takeoff/climb, but cruise will be mostly unchanged due to max continuous being essentially the same between the engines
  • They got permission from Vans to increase Vne to 205ktas (was unclear if this is for the kit in general or just for their testing), and they're easily cruising at 190 ktas up high

FlightAware showed N179RV got taken up to 17,500' last week, and it was really scooting around. Climb was a steady 1600fpm all the way up.
 
NORDO Industries LLC said:
EAA hosted a Webinar this week starring Phil Lockwood, who had some tidbits on the program:
  • Testing is very much still underway, with work being done towards being able to offer a full kit
  • 915/916 can do single-lever power with a CS prop and integration box from RS Flight Systems
  • Getting ~120hp in cruise in Eco-mode (lean-of-peak). 75% of a 160 HP Lycoming. Can do max continuous (135hp, aka 75% for a 180hp Normally-Aspirated engine) up to ~19,500'. Maximum altitude is 22,500', as higher will cause the turbo to over-speed.
  • US engines have 5 year, 2000hr factory warranty, includes major components, fusebox, ECU
  • They're currently using an early 915is, but are planning to swap it out with a 916is soon. Added performance will show up in takeoff/climb, but cruise will be mostly unchanged due to max continuous being essentially the same between the engines
  • They got permission from Vans to increase Vne to 205ktas (was unclear if this is for the kit in general or just for their testing), and they're easily cruising at 190 ktas up high

FlightAware showed N179RV got taken up to 17,500' last week, and it was really scooting around. Climb was a steady 1600fpm all the way up.
Click to expand...
Very cool! The wing on the -9 really is an aerodynamic marvel.
 
skelrad said:
Paul's Kitplanes article on the Rotax 9A

It will come at a premium, but this really does make the 9A even more of a fantastic cross country platform.
Click to expand...
Undoubtedly. In my head, I'm already rolling the numbers around trying to decide where my "flinch point" would be for that conversion. There is a fair bit involved, and I'm sure that Lockwood will want to do the work in their shop as a "conversion" rather than a kit of hardware to release to the builder - which means paying shop rates for their labor.

I'm almost certainly a buyer for a hardware kit - and almost certainly not a buyer for an in-shop conversion.
 
I guess I find myself in a different camp here. While I like the “Experimental“ aviation going on, and have become more impressed with Rotax as the years have gone by, I’m just not a fan of this iteration. My initial take when I first saw the photos from Oshkosh was “Ugly!”. Between the oversized snout and the bulked up tail… it ruins the sleek original lines of the RV. And there are so many other sleek aircraft designs out there already utilizing the Rotax - that it shows that a plane doesn’t have to be disproportionate to use a lighter weight power plant. BUT - I readily acknowledge that beauty is in the eye of the beholder. These are just my own subjective musings.

I am fearful that we’re all in for a rude awakening when the replacement for 100LL shows up and we see the actual pump price. I REALLY like the idea of a Rotax auto fuel burning, efficient cruiser with higher performance, wing loading, and gross weight than the RV12. Hopefully someday when the mothership has stabilized, a sleek new clean-sheet design RV-9 2.0 under MOSAIC will materialize.
 
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airguy said:
Undoubtedly. In my head, I'm already rolling the numbers around trying to decide where my "flinch point" would be for that conversion. There is a fair bit involved, and I'm sure that Lockwood will want to do the work in their shop as a "conversion" rather than a kit of hardware to release to the builder - which means paying shop rates for their labor.

I'm almost certainly a buyer for a hardware kit - and almost certainly not a buyer for an in-shop conversion.
Click to expand...
Not once in my time with Phil did he suggest that this would be anything but a “kit” - I’m sure he’d be happy to have his guys do the install if you wanted to pay for it, but my impression is this is a “ship to your hangar and you build it” kit.
 
In the words of the/a RV-9 designer, the RV-9 rides in turbulence "like a buckboard." Higher cruising speeds would make that worse, but all the better in smooth air, of course. And then there's the issue of carrying Decalin (fuel additive required by Rotax engines using leaded fuel) for refueling away from home base. Lots of advantages to the Rotax, of course, but that's not the whole story...
 
Ironflight said:
Not once in my time with Phil did he suggest that this would be anything but a “kit” - I’m sure he’d be happy to have his guys do the install if you wanted to pay for it, but my impression is this is a “ship to your hangar and you build it” kit.
Click to expand...
That's encouraging. I know they are now looking at testing the 916 versus the 915, I'm looking forward to hearing some real data (flight and financial). This conversion would be an ideal fit for the type of flying I do, and I've got a 1600-hr Lycoming that's going to need SOMEthing done to it in a couple years on my 9A today.
 
Phyrcooler said:
My initial take when I first saw the photos from Oshkosh was “Ugly!”. Between the oversized snout and the bulked up tail… it ruins the sleek original lines of the RV. And there are so many other sleek aircraft designs out there already utilizing the Rotax - that it shows that a plane doesn’t have to be disproportionate to use a lighter weight power plant. BUT - I readily acknowledge that beauty is in the eye of the beholder. These are just my own subjective musings.
Click to expand...

At first, my reaction was the same. But, as I read the article and looked at the photos, the lines grew on me. It looks nice and pointy, a little more fighter-like than most RVs, and the dorsal fin even adds to this. I like the look.

(I mean, look at the Schlepp. Or the Volpar Beaver. At the very least, you have to admit that it could have been so much worse!)
 
You get the feeling the worm is slowly turning towards lycoming alternatives.
Doubling the cost in short order then putting people on multi year waitlists with zero clarity around pricing or delivery is a sure fire way to narrow the gap to all your competitors. (Yes I know that sounds like airframes too…)
 
Ironflight said:
Not once in my time with Phil did he suggest that this would be anything but a “kit” - I’m sure he’d be happy to have his guys do the install if you wanted to pay for it, but my impression is this is a “ship to your hangar and you build it” kit.
Click to expand...
Good news and smart business... he can likely sell a LOT more of them that way.
 
Ed_Wischmeyer said:
In the words of the/a RV-9 designer, the RV-9 rides in turbulence "like a buckboard." Higher cruising speeds would make that worse, but all the better in smooth air, of course. And then there's the issue of carrying Decalin (fuel additive required by Rotax engines using leaded fuel) for refueling away from home base. Lots of advantages to the Rotax, of course, but that's not the whole story...
Click to expand...
Hmmm, I don’t remember him ever describing it that way, and I have made long distance trips in the prototype with him ( but maybe my memory is fading more than I thought).
 
rvbuilder2002 said:
Hmmm, I don’t remember him ever describing it that way, and I have made long distance trips in the prototype with him ( but maybe my memory is fading more than I thought).
Click to expand...
I've flown mine from Savannah to Oshkosh a handful of times and to Arizona once or twice, and to Las Vegas. Big wing + high speed = ... On the other hand, it has been the absolutely perfect plane for all of the flight safety research I've done, especially with the digital data recording. I'm still surprised that nobody has followed up on my work, either to prove or disprove it...
 
Ed_Wischmeyer said:
In the words of the/a RV-9 designer, the RV-9 rides in turbulence "like a buckboard." Higher cruising speeds would make that worse, but all the better in smooth air, of course. And then there's the issue of carrying Decalin (fuel additive required by Rotax engines using leaded fuel) for refueling away from home base. Lots of advantages to the Rotax, of course, but that's not the whole story...
Click to expand...

Decalin is not a requirement to run leaded fuels in the Rotax engine. In fact, it's never mentioned or approved by Rotax in any of the documentation.

Decalin is known to work well, but that's different than it being a requirement. The recommendation from Rotax would be to run the more aggressive service schedule whether running Decalin or not. Of course, on experimental it's builders choice.
 
rvbuilder2002 said:
Hmmm, I don’t remember him ever describing it that way, and I have made long distance trips in the prototype with him ( but maybe my memory is fading more than I thought).
Click to expand...
Agreed. Down low any RV is going to have a rough ride in thermals or mechanical turbulence. The 9A wing lets you quite easily climb above it.
 
Ed_Wischmeyer said:
In the words of the/a RV-9 designer, the RV-9 rides in turbulence "like a buckboard."
Click to expand...
My 9 rides rougher than my 4 did. But to say like a "buckboard" I'm not so sure about that. Like Airguy says, climb above it. The 9 is certainly better than any of my old Citabrias or Cessnas for everything.

Myself with my 160 hp 9A, 15,000 ft or DA of over 16,000ft I will still climbing up at 600 fpm. Leveled out at 157+ kts. Impressive to say the least for 160 hp on a fixed pitch prop. 180 or 200 hp would be soooooo much better.

Like I had mentioned before is that I'm not a rotax guy, but with these performance numbers I could be swayed. Unfortunately I'm running out of years and so it's not likely to happen in this lifetime.

Tim
 
Can’t help thinking that a fraction of the engineering effort that went into the 15 would have delivered a valuable addition to the RV range based on the 9 wing and this engine, and mating it to a new fuselage that addressed the c of g issues, along with new style kit instructions, leveraging the knowledge gained with the 12 design.
Full marks to the effort that has gone into getting this project to this stage, but think it’s appeal will be very limited compared to an in house developed new complete kit.
 
uk_RV9A said:
... a new fuselage that addressed the c of g issues ... it’s appeal will be very limited compared to an in house developed new complete kit.
Click to expand...
On one hand, you're right. With a lighter engine, the ideal thing would be to design a new airplane with the seats a little further forward so that you end up with a CG in the right place without needing the long nose. There is a minor disadvantage: With the seats a little ahead of the CG (rather than right on the CG), the CG location will change depending on the number of occupants and on the pilot weight, and this would require a slightly larger horizontal stabilizer... but this is not a huge problem. The RV-12 manages just fine (as do countless other LSAs).

On the other hand, we are moving into an era where not only are lightweight Rotax engines becoming attractive options, but heavy diesel/jet-A engines are also becoming attractive options. Their higher weights, of course, push the design the opposite way: a retrofitted airplane will try to shorten its engine mount, and an ideal new airplane would have the seats a little further aft relative to the wing. (If you don't think diesel/jet-A engines are attractive, you should see what 100LL costs outside the US).

I, for one, am impressed that RVs (the ones that started out with Lycomings) are versatile enough to be able to take one of the bigger Rotax engines with only a small and manageable amount of nose elongation, or to take one of the heavier diesel engines with only a little bit of engine mount shortening and moving the battery to the back (or not even that, if you're ok having a little less HP at sea level). A so-called "ideal" new airplane, designed around one of the new engines, would only be able to do one but not the other. I would encourage you to appreciate how cool it is that RVs[*] can do either. [*Well, not the 12]. I would hope that future RVs continue to be designed around mid-weight Lycomings, so that they continue to be able to take a more lightweight engine or a heavier diesel.
 
I had an interesting phone conversation yesterday afternoon with Phil Lockwood, of Lockwood Aviation, about this project. Just a few tidbits I gathered from the conversation...
  • They are planning on releasing a full hardware "kit" to builders for their own installation. Their shop and their labor could be made available for the installation, but that's not being looked at yet, the plan is for owner-install of a FWF kit.
  • Half-fuel solo climbs of 1800 fpm are being seen into the upper teens at full power - though the Rotax is time-limited for full power.
  • Cruise speeds in the low 190's knots true in the 17k-19k altitudes in normal "go-fast" mode with higher fuel burn, and 10 knots slower in eco mode (LOP).
  • Good cooling results with the second iteration of the cowl, but they are going to put the 916 in now and test with that to make sure enough cooling is available for the higher takeoff-rated power of the 916. Both the 915 and 916 are rated for 135 continuous.
  • 135hp continuous is available to "about 19,000 feet" according to Phil, at which point it starts to taper off as the turbo is doing everything it can, there ain't nothing left.
  • Service ceiling will be FL230 due to high bearing rpm on the turbo.
  • They expect to be in production by the end of this year. We did not discuss price - I didn't ask and he didn't volunteer.
  • The rudder on the test aircraft is different - some readers here have spotted that it was replaced with not-quite-matching paint, including me. Phil said the rudder was replaced due to damage (not related to testing) and is the exact same design. No control surfaces or empennage surfaces were changed for the increase in Vne (approved by Vans). He told me that Vans approved using the IAS of 182 knots for Vne at altitude as a limiting factor rather than true airspeed. I believe EAA reported 205 ktas (which would be about 147 kias at FL190, depending on temperature) being a limitation, so maybe there is more to this story. This indicates to me (my opinion and zero confirmation) that flutter is not the primary concern for the Vne on the 9/9A model, at least at these expected operating altitudes.
  • A dorsal fin was added from the aft end of the canopy slide track (for a slider) back to the vertical stabilizer to improved yaw stability, in order to counter the longer cowl on the nose.
 
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airguy said:
I had an interesting phone conversation yesterday afternoon with Phil Lockwood, of Lockwood Aviation, about this project. Just a few tidbits I gathered from the conversation...
  • They are planning on releasing a full hardware "kit" to builders for their own installation. Their shop and their labor could be made available for the installation, but that's not being looked at yet, the plan is for owner-install of a FWF kit.
  • Half-fuel solo climbs of 1800 fpm are being seen into the upper teens at full power - though the Rotax is time-limited for full power.
  • Cruise speeds in the low 190's knots true in the 17k-19k altitudes in normal "go-fast" mode with higher fuel burn, and 10 knots slower in eco mode (LOP).
  • Good cooling results with the second iteration of the cowl, but they are going to put the 916 in now and test with that to make sure enough cooling is available for the higher takeoff-rated power of the 916. Both the 915 and 916 are rated for 135 continuous.
  • 135hp continuous is available to "about 19,000 feet" according to Phil, at which point it starts to taper off as the turbo is doing everything it can, there ain't nothing left.
  • Service ceiling will be FL230 due to high bearing rpm on the turbo.
  • They expect to be in production by the end of this year. We did not discuss price - I didn't ask and he didn't volunteer.
  • The rudder on the test aircraft is different - some readers here have spotted that it was replaced with not-quite-matching paint, including me. Phil said the rudder was replaced due to damage (not related to testing) and is the exact same design. No control surfaces or empennage surfaces were changed for the increase in Vne (approved by Vans). He told me that Vans approved using the IAS of 182 knots for Vne at altitude as a limiting factor rather than true airspeed. I believe EAA reported 205 ktas (which would be about 147 kias at FL190, depending on temperature) being a limitation, so maybe there is more to this story. This indicates to me (my opinion and zero confirmation) that flutter is not the primary concern for the Vne on the 9/9A model, at least at these expected operating altitudes.
  • A dorsal fin was added from the aft end of the canopy slide track (for a slider) back to the vertical stabilizer to improved yaw stability, in order to counter the longer cowl on the nose.
Click to expand...
This is good stuff!

The Kitplanes article does say a flutter limit of 200KTAS or 185KIAS, whichever comes first.
 
BTG1996 said:
This set-up would be a great mSLSA for Vans to build. 🤞
Click to expand...
N8DAV8R said:
Also an updated -9 kit for an mELSA. I have been on the fence about what to build next, this would be settle it for me without a doubt.
Click to expand...

If the FAA increases the stall speed allowed for MOSAIC (as many people are hoping, including Van's), then I'd bet that Van's will prioritize the RV-10 (as they already have in Brazil) and the RV-14, over the RV-9.

But if the FAA sticks to its "54-knot VS1" guns, then yeah, I wonder whether Van's would put the work into updating the RV-9... or would develop a bigger wing for the RV-14. Who knows.

I would guess; Probably the latter. Adding span to the RV-14 would be less work than updating the RV-9 to final-size holes (let alone creating RV-14-style assembly instructions for the 9, if that's what "updated" means). Enlarging the 14 wing could be as simple as bolting RV-10 wings onto a 14... No, probably not quite that simple: Some back-of-the-envelope math shows that you'd need 166 square feet of wing to bring the VS1 of the RV-14 from 62 knots to 54 (126 times the square of 54/62), and the RV-10 only has 148 square feet. Maybe 148 would be enough with the use of vortex generators, and/or a lower "zero degree" flap position relative to the current 3 degrees below cruise-reflex...

... but, I apologize, I don't want to pull this thread away from the RV-9. Between MOSAIC (if the stall speed requirements stays where it is) and this new engine, the RV-9 could indeed see a boost in popularity, which could warrant some re-engineering (final-size holes, maybe better assembly instructions) to reduce the person-hours needed on the production line. That would be cool.
 
The article talks about just stopping at firewall forward from the standard kit. Given that I may be right on cue for a powerplant design change if they really do have something ready to go this summer/fall, it's definitely got me thinking (although I'd have to sell my Titan IO-340 that would probably be shipping about then). It seems like there's more sunk cost than what the article talked about though, since some of the costly firewall forward items come in other kits. For instance, I already have the engine mount and cowl. I'm also curious, I've already set up the fuel system with the standard injected engine fuel pump. Does all of that change in a Rotax setup as well?

In all likelihood, I'll just keep on with my current plan, but if the cost of the change to Rotax isn't astronomical and I'm able to sell parts that came with the kits already, it's really going to make me pause and consider it. The use of this plane is primarily for cross country cruising, but low speed wandering around while sipping gas at Rotax efficiency is high on the list as well.
 
skelrad said:
. I'm also curious, I've already set up the fuel system with the standard injected engine fuel pump. Does all of that change in a Rotax setup as well?
Click to expand...
I am assuming that the 915/916 systems are the same as the 912iS.
If I am correct, then the answer is yes.
 
AirShowFan said:
If the FAA increases the stall speed allowed for MOSAIC (as many people are hoping, including Van's), then I'd bet that Van's will prioritize the RV-10 (as they already have in Brazil) and the RV-14, over the RV-9.

But if the FAA sticks to its "54-knot VS1" guns, then yeah, I wonder whether Van's would put the work into updating the RV-9... or would develop a bigger wing for the RV-14. Who knows.

I would guess; Probably the latter. Adding span to the RV-14 would be less work than updating the RV-9 to final-size holes (let alone creating RV-14-style assembly instructions for the 9, if that's what "updated" means). Enlarging the 14 wing could be as simple as bolting RV-10 wings onto a 14... No, probably not quite that simple: Some back-of-the-envelope math shows that you'd need 166 square feet of wing to bring the VS1 of the RV-14 from 62 knots to 54 (126 times the square of 54/62), and the RV-10 only has 148 square feet. Maybe 148 would be enough with the use of vortex generators, and/or a lower "zero degree" flap position relative to the current 3 degrees below cruise-reflex...

... but, I apologize, I don't want to pull this thread away from the RV-9. Between MOSAIC (if the stall speed requirements stays where it is) and this new engine, the RV-9 could indeed see a boost in popularity, which could warrant some re-engineering (final-size holes, maybe better assembly instructions) to reduce the person-hours needed on the production line. That would be cool.
Click to expand...

I mean, I guess if you want to make it about stall speed and wrestle this into a discussion about completely different airplanes and engines then you have a point.

Anyway, updating a kit would mean more than just final sized holes. It would mean a comprehensively engineered package for the engine, avionics, etc. It would most likely be built like the E-LSA RV-12 with little to no design work or third party sourcing required by the builder. I don't think this is likely to happen, but a guy can dream.
 
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