TwinJAG - Corvair powered Twin coming to Oshkosh

Followed the project closely. A remarkable feat. I'd like very much to have the opportunity to talk with Him about some of the nitty gritty engineering details on this design concept.

I have had similar ideas about constructing an experimental twin since the majority of my flying has been in the multiengine category. I grow less and less comfortable in a single.
 
It sounds awesome. What's it based on?
 
Here's a video I shot at Corvair college # 31 at KBNL back in 2014. At 7:20 in the video you can see Jim & Ginger working on the engines and my friend asking and getting answers to some of the build questions:

 
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Funny. My wife and I taxied past it yesterday. They departed 27 right after me. She asked what it was and I said, “don’t know…looks like a twin RV”. :)
 
Tarheelpilot said:
How does the corvair engine hold up? Is it reliable?
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Not sure there are enough out there to draw a conclusion. There are a slew of modifications that can/should be done to make them aircraft worthy. Sadly by the time you do that you are getting into small continental or Lycoming money.
 
Tarheelpilot said:
How does the corvair engine hold up? Is it reliable?
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I have a 3.0 Corvair and it has been very good to me but I only have 260 hours on it.

When I was building my plane the main engine contenders at that time were the manufacturer's 80 HP VW conversion, (I had one of those on a nose wheel version Sonex I owned before this one and it wasn't enough power. They have a turbo for them now but I'm not in the group that thinks that's a good idea), the Jabiru 3300 was an option but besides the cost the company was (some say still are) having issues with those engines, or a Corvair conversion. Other engines could have been adapted but finding an engine mount would have been problematic.

The Corvair conversion I have has all of the conversion upgrades and was built by Dan Weseman of SPA and uses his engine mount, fifth bearing (prop loads) baffling kit, and cowling design. At that time the engine was in the 10K range.

Prices have gone up over the years but the real value is when it comes time for repair, rebuild, or just buying parts. It really is a great fit for my aircraft as it cruises at light sport speeds, is smooth, and has been very reliable.
 
"Twin Jag" is worse in every measure vs just calling it "RV66" and throwing Van an official tongue-waggle. :D :tongue:
 
schmookeeg said:
"Twin Jag" is worse in every measure vs just calling it "RV66" and throwing Van an official tongue-waggle. :D :tongue:
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If Vans is like Sonex, they don't want their name mentioned at all. A Corvair on a Sonex is verboten by the kit supplier.

BTW - JAG is for Jim And Ginger!
 
Daleandee said:
If Vans is like Sonex, they don't want their name mentioned at all. A Corvair on a Sonex is verboten by the kit supplier.

BTW - JAG is for Jim And Ginger!
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I doubt they trademarked the letters R and V and what could they even do about it?
 
schmookeeg said:
I doubt they trademarked the letters R and V and what could they even do about it?
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I get what you are saying. But I believe Jim left it alone in order to try and keep the peace with the kit supplier.

I attempted to do the same but the registration paperwork still shows who the kit supplier was and it's not like most people don't know what mine is from looking at it.

With the JAG the origin of the kit might not be apparent to many that are not builders.
 
For any that would like to understand the "why" of the Twin JAG:

 
So the twin has almost no performance increase over the single? I guess he gets his gas for free?

I'd install a BRS before I went to a twin.
 
pfarber said:
I'd install a BRS before I went to a twin
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Then you are in the category of people that aren't willing to commit to training enough to fly twins.

No shame there, but I would rather have another engine than a BRS.

Make it to the other side of the lake to land for repairs, maybe even get a restart, turn back to land, etc. Even shoot an approach to a bonafide airport!

OR!!

Float gently downward, not toward the shore, to almost certain hypothermia and death within an hour. Sure you could pack a raft and some space blankets, but if you've ever been on, over, or near Lake Michigan when it's angry you'd understand why those items night not do you any good anyway.

The Coast Guard is wonderful, but even their helicopter might not get swimmers to you in time. In fact, it's more likely they won't.

"I don't fly over water like that so your scenario is moot!" someone may think.

Ok, how about those giant, mature North American hardwood stands? Or our sizeable inland lakes? It gets pretty remote pretty fast in this glorious country (and in many others!). Do you have the skills and equipment to survive overnight after deploying your BRS? You might have to.

Just things I think about often. Yesterday I flew an ILS with the critical engine dead, and even had to go around on one. This is why we train.
 
Der Fliegermeister said:
Then you are in the category of people that aren't willing to commit to training enough to fly twins.

No shame there, but I would rather have another engine than a BRS.

Make it to the other side of the lake to land for repairs, maybe even get a restart, turn back to land, etc. Even shoot an approach to a bonafide airport!

OR!!

Float gently downward, not toward the shore, to almost certain hypothermia and death within an hour. Sure you could pack a raft and some space blankets, but if you've ever been on, over, or near Lake Michigan when it's angry you'd understand why those items night not do you any good anyway.

The Coast Guard is wonderful, but even their helicopter might not get swimmers to you in time. In fact, it's more likely they won't.

"I don't fly over water like that so your scenario is moot!" someone may think.

Ok, how about those giant, mature North American hardwood stands? Or our sizeable inland lakes? It gets pretty remote pretty fast in this glorious country (and in many others!). Do you have the skills and equipment to survive overnight after deploying your BRS? You might have to.

Just things I think about often. Yesterday I flew an ILS with the critical engine dead, and even had to go around on one. This is why we train.
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That's quite a bit of fan fiction.

You never really hear much about the people who pulled the chute and died, do you? Maybe because they don't?

Two engines don't stop CFIT, do they? When you run out of gas, what does that second engine do for you? Other than increase the amount og kinetic energy you have to dissipate when you slam into the ground.

I have no desire to look up stats, but I bet a warm diet walmart cola that more people died in twin engine crashes than in in BRS events (aka the BRS is deployed).

The fallacy that dragging around a spare engine is a good idea is not really that good of an idea. I'd rather float gently down immediately than try and nurse a dying /dead plane to something resembling any sort of landing strip.
 
pfarber said:
That's quite a bit of fan fiction.

You never really hear much about the people who pulled the chute and died, do you? Maybe because they don't?

Two engines don't stop CFIT, do they? When you run out of gas, what does that second engine do for you? Other than increase the amount og kinetic energy you have to dissipate when you slam into the ground.

I have no desire to look up stats, but I bet a warm diet walmart cola that more people died in twin engine crashes than in in BRS events (aka the BRS is deployed).

The fallacy that dragging around a spare engine is a good idea is not really that good of an idea. I'd rather float gently down immediately than try and nurse a dying /dead plane to something resembling any sort of landing strip.
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No fiction at all.

BRS systems have only been available on certified GA airplanes for a handful of years compared to the many decades twins have been around.

You can't say "you never really hear about XYZ do you?" and then follow it up with "I have no desire to look up stats." That's just a horrible way to convince someone to take you seriously and grants no weight to your judgement of what qualifies as, "fan fiction."

Single engine fixed-gear airplanes make up over 70% of fuel starvation accidents if you thumb through the Nall report. Single complex is next at roughly 17%. Multi-engine, just over 11%.

This is NOT to say these things can't or don't happen, which is the overall point I was making. I can't drink diet soda, but I appreciate the offer.

Deploying a BRS in that shiny plastic bird that starts with a "C" totals the airplane. I'm not really keen on that. Not to mention the mandatory $12k repack every ten years. Starts to look more like an expense sheet for a Robinson!

With respect to CFIT: just 1% were multi-engine. I fully admit that I haven't done the math to account for the fact that there are just more single-engine airplane operations in a given sample. But I'd bet the weighted figure won't make up for a 99% gap...

That said, I'm very pleased that lives have been saved by BRS deployments over the last decade or so. But it would be a statistical fallacy to assume that those accidents would have resulted in fatalities if the BRS wasn't there or wasn't used. Some would, but definitely not all of them.

I can fly just as fast and just as far in a twin as you can in a modern piston single. It may (not always) cost more in fuel, but the airplane also didn't cost $1.2 mil....

Aviation is about risk management. I'm comfortable flying twins because I fly a lot and train on every flight. "Dragging around a spare engine," as you say, turns out to be a real useful thing in the right mission and with consistent training to maintain the appropriate skills. It's just not always the most practical option for everyone for a whole host of reasons. That's all perfectly fine.
 
I consider a BRS equivalent safety to a second engine.

In addition to the (mucho) extra gas for very (sigh, VERY) few extra knots, I consider the second engine also costs me 20 hours of training/practice per year.

There is some crossover point where I'd have been better off just buying a Cirrus to begin with. I think it's still in the 15-20 year range, though, so I continue to enjoy the fuel economy of an oil fire, the (self-imposed) recurrent training demands of an MU2 pilot, and relative calm when flying over rocks and water and over LIFR.

I would agree that twins are likely much more lethal than BRS-equipped aircraft pilots, even normalizing for the recent availability of the BRS and hours flown. It's just more work to do twins well, and safely, and you never reallllly know if you've done it all well enough until the pop quiz. :)
 
schmookeeg said:
I consider a BRS equivalent safety to a second engine.

In addition to the (mucho) extra gas for very (sigh, VERY) few extra knots, I consider the second engine also costs me 20 hours of training/practice per year.

There is some crossover point where I'd have been better off just buying a Cirrus to begin with. I think it's still in the 15-20 year range, though, so I continue to enjoy the fuel economy of an oil fire, the (self-imposed) recurrent training demands of an MU2 pilot, and relative calm when flying over rocks and water and over LIFR.

I would agree that twins are likely much more lethal than BRS-equipped aircraft pilots, even normalizing for the recent availability of the BRS and hours flown. It's just more work to do twins well, and safely, and you never reallllly know if you've done it all well enough until the pop quiz. :)
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Nice pun on "pop quiz" :D
 
I saw that thing at Oshkosh. When I first chanced upon it all I saw was blankets and shrink wrap, they were worried about the forecast hail the previous evening. I chatted with them about it as they removed the coverings. Thing looked like an Apache that had shrunk in the wash. Really nice people, nice to see they got the attention they were looking for.
 
Der Fliegermeister said:
Single engine fixed-gear airplanes make up over 70% of fuel starvation accidents if you thumb through the Nall report. Single complex is next at roughly 17%. Multi-engine, just over 11%.
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You have to love stats! Of course single-engine fixed-gear airplanes make up around 87% of fuel starvation accidents. They also make up more than 87% of all accidents. 87% of the fleet. 87% of training aircraft...

AOPA reports that in 2017, the number of airplanes active in general aviation were:
Single Engine 130,330 90%
Multi Engine 12,935 10%
 
82.7% of all statistics are made up on the spot. :p
 
Lowflynjack said:
You have to love stats! Of course single-engine fixed-gear airplanes make up around 87% of fuel starvation accidents. They also make up more than 87% of all accidents. 87% of the fleet. 87% of training aircraft...

AOPA reports that in 2017, the number of airplanes active in general aviation were:
Single Engine 130,330 90%
Multi Engine 12,935 10%
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Der Fliegermeister said:
I fully admit that I haven't done the math to account for the fact that there are just more single-engine airplane operations in a given sample
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You: SIOecIDH.jpg

At least I went and got some numbers at all. The amount of times I see pilots make safety decisions based on conjecture from the less-than-50-hours-per-year peanut gallery is troubling.
 
Der Fliegermeister said:
You: View attachment 99116

At least I went and got some numbers at all. The amount of times I see pilots make safety decisions based on conjecture from the less-than-50-hours-per-year peanut gallery is troubling.
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It just gets tricky when looking at stats and I don't know what the right answer is. I'm sure the Cessna 172 and Vans Aircraft have more fatalities than other aircraft... also make up a huge amount of the fleet.

Chutes are even tougher to figure out. Yeah, most people survive when they deploy one, but how many didn't need to be deployed or how many pilots just don't know how to fly the slick Cirrus and compensate for their lack of training by pulling the chute?

Luckily my budget will dictate that I don't fly a Cirrus or a Twin, so I just have to worry about burning a singe-engine hole in the ground.
 
Der Fliegermeister said:
BRS systems have only been available on certified GA airplanes for a handful of years compared to the many decades twins have been around.
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It's been 20+ years for Cirrus.

That's a really big hand with a lot of fingers. :p:D

Light twins have been around for much longer than that.
 
Der Fliegermeister said:
No fiction at all.

BRS systems have only been available on certified GA airplanes for a handful of years compared to the many decades twins have been around.

You can't say "you never really hear about XYZ do you?" and then follow it up with "I have no desire to look up stats." That's just a horrible way to convince someone to take you seriously and grants no weight to your judgement of what qualifies as, "fan fiction."

Single engine fixed-gear airplanes make up over 70% of fuel starvation accidents if you thumb through the Nall report. Single complex is next at roughly 17%. Multi-engine, just over 11%.

This is NOT to say these things can't or don't happen, which is the overall point I was making. I can't drink diet soda, but I appreciate the offer.

Deploying a BRS in that shiny plastic bird that starts with a "C" totals the airplane. I'm not really keen on that. Not to mention the mandatory $12k repack every ten years. Starts to look more like an expense sheet for a Robinson!

With respect to CFIT: just 1% were multi-engine. I fully admit that I haven't done the math to account for the fact that there are just more single-engine airplane operations in a given sample. But I'd bet the weighted figure won't make up for a 99% gap...

That said, I'm very pleased that lives have been saved by BRS deployments over the last decade or so. But it would be a statistical fallacy to assume that those accidents would have resulted in fatalities if the BRS wasn't there or wasn't used. Some would, but definitely not all of them.

I can fly just as fast and just as far in a twin as you can in a modern piston single. It may (not always) cost more in fuel, but the airplane also didn't cost $1.2 mil....

Aviation is about risk management. I'm comfortable flying twins because I fly a lot and train on every flight. "Dragging around a spare engine," as you say, turns out to be a real useful thing in the right mission and with consistent training to maintain the appropriate skills. It's just not always the most practical option for everyone for a whole host of reasons. That's all perfectly fine.
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First, BRSs have been around since the 90's. Cirrus just made them household names. An STC for 172 BRS goes back to the early 2000s. 21 years is 4 'handfulls' of fingers. Plus a toe. Currently you can get a BRS for just about any E/AB. Yet almost none have a 2nd engine option. Specifically for the 'twin corvair' you are not even getting the FAA mandated single engine climb requirements.

A BRS deployment may or may not total an aircraft. It may or may not destroy a Cirrus, but insurance is a thing. There are at least 19 SR's flying with at least one CAPS deployment (aka rebuilds). Whats the landing speed of a light twin and how much runway do you need? A BRS? 0 feet and 0 ground speed.

BRS repacks are not $12k across the board. The 172 repack is $7k. Many BRS systems are less. Even if its $12k for a Cirrus, I think its a safe bet that if you are driving a 2021 SR22 you are not concerned about a minor cost like a $12k repack that is 0.016 of your purchase price. How much does a new spare motor cost that you have to drag around? Can you get a 0 timed motor for $12k?

Also a BRS can get you an insurance discount.

I get that you believe you are safer, but multi's are not the saving grace you claim they are.

I can (but won't) cite you a plethora of articles that show that no, that spare engine is not making you 'safer'. I will agree that the level of pilot training is the more important factor.

I did find this the most enlightening (and somewhat recent)

https://www.avweb.com/ownership/do-you-really-want-a-twin/
 
pfarber said:
I will agree that the level of pilot training is the more important factor.

I did find this the most enlightening (and somewhat recent)

https://www.avweb.com/ownership/do-you-really-want-a-twin/
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Alas, there is always common ground! I didn't mean to claim that twins are a "saving grace," as you allege I implied.

I've read that article many times as I've discerned getting into the multi-engine game. It offers a good overview of the topics one should concern themselves with if looking at making the jump.

The one thing I'll poke at this round: you couldn't pay me to fly in a rebuilt Cirrus that's had a CAPS deployment.

Admittedly, my angst for the SR series stems from having worked on them. Total nightmare.

Might I also add that I appreciate this match of cordial disagreement. I have not been offended and I do hope you feel the same. If not, please accept my apologies.
 
If you ever look at the maintenance records of some of the certified AC you would probably not fly them either. 10-20-50+ year old airframe is can have scary maintenance repairs/alterations... And who knows what wasn't logged during that time?

I'd take a factory repaired SR22. When you think about it, even factory overhauled zero timed engines may contain used parts like cases/cranks etc as long and they meet new specs. That's the scary part.
 
pfarber said:
I'd install a BRS before I went to a twin.
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The two aren't really comparable, just a few examples:
-a BRS won't do you any good crossing lake Michigan.. that plane sinks and you're just a little head bobbing in water. The Coast Guard is awesome, but I'd take my chances flying a twin proficiently back to land rather than waiting for hypothermia to kick
-a twin won't help you with LOC IMC.. but a chute will
-a twin won't help with a bad icing encounter.. but a chute will
-most twins have awesome climb performance, and generally good load carrying ability, this is very important for many


Der Fliegermeister said:
Then you are in the category of people that aren't willing to commit to training enough to fly twins.

No shame there, but I would rather have another engine than a BRS.
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!!! I totally agree

pfarber said:
You never really hear much about the people who pulled the chute and died
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That's a spurious data point. You also never really hear much about people who have an engine issue in a twin and make it home safely. Sure, people die in twins. People also die in planes with chutes, and in planes that "have a roll bar and amazing glide range".. and to boot people have also died pulling the chute, not many, but they have. The COPA page lists all chute pulls, including the fatals. I'm a HUGE fan of what Cirrus has done, it's the best modern compromise of speed and comfort, but the chute is not a panacea.

Close to the ground, maneuvering, which is where most people have accidents, you are no better with a chute or a twin. If you lose one at 300 AGL just fly the plane to the crash. There was a Death, err, Aerostar at Ramona a few years ago. The left engine completely came apart, something with one of the jugs. Anyway.. a plane that is notoriously a handful, even with both engines, was safely sitting there at Ramona on the ramp. And I suspect with a jug torn in half he had no oil pressure either to feather the dead engine..!

schmookeeg said:
I consider a BRS equivalent safety to a second engine.
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I've been on a multi kick but there are applications where I miss the chute. It's nice always having that ultimate bail out option. But when push comes to shove at night or over the water you just can't replace the second engine, in my opinion. The current state of the world puts me in the minority but whatever
 
pfarber said:
If you ever look at the maintenance records of some of the certified AC you would probably not fly them either. 10-20-50+ year old airframe is can have scary maintenance repairs/alterations... And who knows what wasn't logged during that time?

I'd take a factory repaired SR22. When you think about it, even factory overhauled zero timed engines may contain used parts like cases/cranks etc as long and they meet new specs. That's the scary part.
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This is absolutely true. I used to fly anything someone would give me the keys to. Then I got into the maintenance world.... That opportunism faded quickly
 
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