Twin Engine Corvair powered JAG-2

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Daleandee

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It does fly! A twin engine Corvair powered aircraft. I first met and talked with this gentleman and his wife at Corvair college # 31 at Barnwell SC. He's in this video along with the engines being built (starts at 7:20):

https://www.youtube.com/watch?v=S_PVD1M1AXo

William Wynne has the story on his site here:

https://flycorvair.net/2018/08/30/jag-2-corvair-powered-twin-now-airborne/

And I found some flight footage on You Tube here:

https://www.youtube.com/channel/UCMVAw0IwvmngeA6qvKN_F7g

But if you want to see the first flight video just click here:


My oh my ... don't them 'vairs sound great!

Dale
N319WF
 
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Daleandee

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Here's the proposed paint scheme for the plane after the 40 hour phase one is completed:



Dale
N319WF
 

BJC

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Dale:

What type of propellers does it have?

Can they be feathered?

Any information on single engine performance?

Thanks,


BJC
 

Daleandee

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Dale:

What type of propellers does it have?

Can they be feathered?

Any information on single engine performance?

BJC
Wish I could give some answers for those questions but I have none as yet. The builder, Mr. Jim Tomaszewski, has said he would do a write up on his project in the coming days and I'm hoping that an aviation publication will do a story on this aircraft. There have been reported Corvair twin projects over the years but to my knowledge this is the first that has flown.

If I get answers to any of these questions I'll send them along.

I just think what this man has done is pretty phenomenal.

Dale
N319WF
 

Toobuilder

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Looks very nice, but I have to ask what it weighs? How much power does each engine have?
 

mcrae0104

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BJC
Can they be feathered?
The propellers are fixed pitch. I don't know what type. Jim's plan (at least several years ago when I talked with him at Corvair College 31) was to use something similar to a bicycle disc brake to prevent windmilling.

How much power does each engine have?
3,000 cc => 115 hp @ 3,000 rpm according to dyno test by SPA.

Capture.jpg
 
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Direct C51

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I really don't know much about this airplane, but I would say there is a 99% chance they are wood props. You have to try really hard to get wood props on a Corvair to windmill.
 

Vigilant1

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I'm betting the airplane is at minimum 250 pounds heavier than an RV-7, so single engine flight on 115 HP is going to be "interesting".
Based on the info in the article linked by lr27:
Estimated empty weight: 1400 lbs
Estimated max gross: 2150 lbs
It started life as an RV-6A (Van's site: 965 lbs empty, 1600 lbs gross). The span of this twin is 26' 6", which is 3' 6" more than the 23' 0" of the stock RV-6A.
 

lr27

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I wonder what VMC is. Did he enlarge the fin and rudder?
 

TFF

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Prop brakes instead of constant speed. I would like to know how that test goes. See the mechanism.
 

BoKu

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More here:
https://flycorvair.net/2013/02/01/jag-2-corvair-powered-twin-jim-tomaszewski-n-y/

I don't see any mention of major changes in the structure. I should think that, with those engines hanging out there on the wings, a higher gross weight, and a larger span, some significant changes would be required.
I wouldn't be so certain. Mounting the engines on the wings provides inertia relief that reduces wing bending moment at the side of body. So the wing spars are likely fine as-is even with short tip extensions. I'd worry more about wing torsion between the nacelles and fuselage, and I seem to recall they've used thicker skins in that area to address that issue.

My main concern with this project has always been that it probably has a very low single-engine service ceiling. It has only a little more horsepower than an IO-360 powered RV-6, but with a much greater engine and systems mass. Part of that is there are two of a lot of things that don't scale well with horsepower. There are two engine mounts, two cowlings and nosebowls, two spinners, two sets of engine controls, etc. Each of these can be a bit lighter and simpler for a 115 hp engine than for a 200 hp engine, but the total is still heavier per unit hp than they would be for a single engine. With the indeterminate reliability of the Corvair motors, and the doubled chance of engine failure with two engines, I suspect that it will prove to be slower and less safe than its single-engine brethren. But, hey, to each their own. My money is on this airplane reappearing sometime in the future with a pair of strapping O-320s, which would make it a ripping combo.

Edit Add: I pretty much said my piece on this (as did Ross and a couple other familiar names) in this VAF thread dating back to 2011:

http://www.vansairforce.com/community/showthread.php?t=79356

--Bob K.
 
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Daleandee

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Here is a short piece of in flight footage from the JAG-2. Sounds awesome!

Stopping the video at various places will allow you to see some engine information numbers. Excellent numbers overall.


[video=youtube_share;PCZPHMVhXfA]https://youtu.be/PCZPHMVhXfA[/video]

Dale
N319WF
 

blane.c

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capital district NY
I wouldn't be so certain. Mounting the engines on the wings provides inertia relief that reduces wing bending moment at the side of body. So the wing spars are likely fine as-is even with short tip extensions. I'd worry more about wing torsion between the nacelles and fuselage, and I seem to recall they've used thicker skins in that area to address that issue.

My main concern with this project has always been that it probably has a very low single-engine service ceiling. It has only a little more horsepower than an IO-360 powered RV-6, but with a much greater engine and systems mass. Part of that is there are two of a lot of things that don't scale well with horsepower. There are two engine mounts, two cowlings and nosebowls, two spinners, two sets of engine controls, etc. Each of these can be a bit lighter and simpler for a 115 hp engine than for a 200 hp engine, but the total is still heavier per unit hp than they would be for a single engine. With the indeterminate reliability of the Corvair motors, and the doubled chance of engine failure with two engines, I suspect that it will prove to be slower and less safe than its single-engine brethren. But, hey, to each their own. My money is on this airplane reappearing sometime in the future with a pair of strapping O-320s, which would make it a ripping combo.

Edit Add: I pretty much said my piece on this (as did Ross and a couple other familiar names) in this VAF thread dating back to 2011:

http://www.vansairforce.com/community/showthread.php?t=79356

--Bob K.
Prove to me by mathematical probability analysis that the chance of engine failure is doubled because it is a twin or even a tri engine, I triple dog dare you. No self respecting man can turn down a triple dog dare!
 
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