...Projects don't need to be especially practical or efficient, just fun and educational...
Ross, that is an excellent point, and there are many other gems of wisdom in your post.
However, in my thirty or so years dabbling in experimental airplanes, the cases where a builder really is experimenting, and is not interested in practicality or effectiveness are a pretty tiny minority. If this is indeed one of those cases, then it's all good. I admit to my preconceived notions about how it will turn out, but I will be as interested as anybody in the results.
I have seen too many homebuilt airplanes result in a lot of heartache in the very real sense of the word. I have seen people put a lot of work and time and money into machines that, while fascinating in and of themselves, did not nearly achieve the return on investment intended.
In the majority of the cases where I have seen unusual innovations, it is people thinking that they know of a shortcut between where they are and where they want to be, which is zooming around and boring holes in the sky. And too often those shortcuts turn out to actually be the long way around. And just as often, some critical thinking and a few flips of a slide rule would be all that is required to reveal the potential pitfalls ahead.
...I question the decision to use Corvair engines as that is bringing in another departure from the normal tried and tested aviation engine options that are available...
...The tail was swapped for a -9 tail and 40 inches were added to the wings...
Putting the biggest vertical tail and rudder on it that will practically fit is also exactly what I'd expect to see. That helps keep the blue line speed low. Below blue line speed, if you lose an engine you have to throttle the remaining engine back until you have enough speed so that the rudder and vertical tail are effective enough to counter the asymmetrical thrust. And if you don't have altitude to trade for that speed, you're in a bad situation.
That would be redline speed, Vmc....
I have to agree with Bob in post #47. I do laud the true spirit of "Experimental" that the builder/modifier is bringing into this project but I question the decision to use Corvair engines as that is bringing in another departure from the normal tried and tested aviation engine options that are available. Single engine aircraft have a much better safety record than light twins. Some say the purpose of the second engine is to take the aircraft to the scene of the crash. I also question the choice of airframe. Maybe cost is a factor. I would be applying my efforts to an RV-10 airframe rather than a 6A. When the project is finished what will be the resale value be? A 10 fitted with two 200hp engines would command a better resale price, have two extra seats and is a more realistic conversion IMHO.
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Dare I say, too many here have almost taken on a "sheeple" attitude, criticizing projects that stray very far from the flock. I say let's let the dreamers dream and build something unique that satisfies their desire for something different.
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I have so often wanted to say it but I have never quite found the words. I will not copy you but I appreciate your saying them.
Bob Axsom
The weight you quoted for an IO360 is NOT all up flying weight. I weighed my O360 bare with no accessories, and it was 240lbs. Add all the accessories, fluid lines, everything to make it ready to fly, and it will be over 400lbs.<snip>For the twin we're talking about here, I think we will see that 2x110hp won't really be enough. According to www.flycorvair.com, the installed weight for a single 110 hp corvair motor ready to fly is 215 lbs or so. So for 220 horsepower worth of them, it is 430 lbs of weight, versus the single IO360s 300 lbs or so for 200 hp<snip>
Thanks, Bob K.
Best post in this thread IMHO...I think many people here are simply missing the point of this project and perhaps the essence of true experimental aviation. For many, they simply want to do something different or they have a dream. Projects don't need to be especially practical or efficient, just fun and educational.
Really, building a hole matched RV with a Lycoming up front, while still being a truck load of works and hours, isn't very "experimental" other than by category.
While many might question the practicality to add retractable gear, floats or another engine to RVs, I personally think these are all pretty cool mods because they are so different and involve a lot of independent thought and design/ fab work.
Dare I say, too many here have almost taken on a "sheeple" attitude, criticizing projects that stray very far from the flock. I say let's let the dreamers dream and build something unique that satisfies their desire for something different.
Jim has the experience to make this work. Lots of engineering work done (three years worth), and lots of twin engine experience (97% of Jim's 15,000 hours of flight time are multi-engine hours).Some of us will go to the extremes to have a one of a kind but this is an accident waiting to happen.
An amazing effort but don't you think Van considered building kit twins and thought better of it... I hope it ends up a static display before it becomes a deathtrap.
Because it's not an RV...well, it was an RV, and now it's modified to be something else, and it just "doesn't fit". Too bad...it's one of the most interesting projects out there right now that I know of. And I know of A LOT of them now.This has to be one of the coolest projects yet and I don’t understand why this community is not more supportive.
I can personally guarantee you that resale value is not even on his radar. Besides...it's not your dollars he is spending, so who cares, really?When the project is finished what will be the resale value be?
I think many people here are simply missing the point of this project and perhaps the essence of true experimental aviation. For many, they simply want to do something different or they have a dream. Projects don't need to be especially practical or efficient, just fun and educational.
Really, building a hole matched RV with a Lycoming up front, while still being a truck load of works and hours, isn't very "experimental" other than by category.
While many might question the practicality to add retractable gear, floats or another engine to RVs, I personally think these are all pretty cool mods because they are so different and involve a lot of independent thought and design/ fab work.
Dare I say, too many here have almost taken on a "sheeple" attitude, criticizing projects that stray very far from the flock. I say let's let the dreamers dream and build something unique that satisfies their desire for something different.
I seriously looked at doing almost the same thing before buying my RV10 kit. I was planning twin 130hp Suzuki 1.3 turbos with gearboxes on a modified RV7 airframe. I ran into design issues mounting the nacelles over the fuel tanks and couldn't get past not being able to source suitable full feathering props so I called it quits there.
I briefly considered a push/pull design like the Do 335 WW 2 fighter using RV7 wings and tail feathers and the same Suzuki engines until the design realities with the rear engine driveshaft system and a complete custom fuselage brought me to my senses!
I can personally guarantee you that resale value is not even on his radar. Besides...it's not your dollars he is spending, so who cares, really?
To be honest Chad mate, I do not care who's money he is spending as long as it not mine. Seems your telling me to mind my own business.
Not at all Anthony...more of a general statement of 'to each his own'. Sorry about that. Internet talk...hard to convey how I was actually "speaking".
Are there any more updates to this interesting project?
Just a myth? Jeez.
http://en.wikipedia.org/wiki/Wing_Derringer
John Clark ATP, CFI
FAAST Team Representative
EAA Flight Advisor
RV8 N18U "Sunshine"
KSBA
The engines have a 5th bearing.For you thinking about using Corvair power, the front bearing is not adequate to support the prop, and the thrust bearing on the crank is at the back, away from the prop. At a minimum, the Corvairs need a prop bearing add on, which puts this in the realm of the Subaru auto conversion. Really dangerous to fly without an added prop bearing. And Corvair parts are hard to get. Everytime we looked at Corvair power, it seemed a Lycoming out of a Cessna 150 was cheaper.
For you thinking about using Corvair power, the front bearing is not adequate to support the prop, and the thrust bearing on the crank is at the back, away from the prop. At a minimum, the Corvairs need a prop bearing add on, which puts this in the realm of the Subaru auto conversion. Really dangerous to fly without an added prop bearing. And Corvair parts are hard to get. Everytime we looked at Corvair power, it seemed a Lycoming out of a Cessna 150 was cheaper.
Oh no someone is going to accuse you of "misinformation"... Ha ha.For you thinking about using Corvair power, the front bearing is not adequate to support the prop, and the thrust bearing on the crank is at the back, away from the prop. At a minimum, the Corvairs need a prop bearing add on, which puts this in the realm of the Subaru auto conversion. Really dangerous to fly without an added prop bearing. And Corvair parts are hard to get. Every time we looked at Corvair power, it seemed a Lycoming out of a Cessna 150 was cheaper.
Don't get upset. This is a cool project and appreciate you sharing. Everyone is going to have opinions. Get ready. Clearly you are a proponent and passionate about Convair power. I have seen at least one RV (single engne) with a Convair. It was for sale cheap. Just saying. I have seen the Convair booth at Airventire a few times.Stop misleading people with misinformation….the TwinJAG has 5th bearings with dedicated oil lines and high volume oil pumps. This setup addresses thrust and gyroscopic loads on the crankshaft. BTW, Corvair aircraft engine parts are VERY easy to obtain.
I am the designer & builder of this aircraft and reading posts by misinformed internet armchair quarterbacks like this makes you lose faith in fellow so called “builders”. To all so called experts, please put down your keyboards and come see me at my aircraft at Oshkosh and would be glad to inform you on how it was really built.
BTW, C-150’s use Continental Engines
And yet, not familiar enough with it to spell Corvair correctly.Don't get upset. This is a cool project and appreciate you sharing. Everyone is going to have opinions. Get ready. Clearly you are a proponent and passionate about Convair power. I have seen at least one RV (single engne) with a Convair. It was for sale cheap. Just saying. I have seen the Convair booth at Airventire a few times.
I would be interested in wing attach as the carry through forward spar had to have moved forward to balance with the weight of the two engines. the spar had to have moved forward to the firewall to keep it out of the way of the leg room and rudder peddles.