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"Why not build a twin?"

Palamedes

Palamedes

Well Known Member
So I was talking to a buddy of mine about the fact that I'm starting an RV-10 build (the Emp is almost here! *glee*) and he didn't approve for all the usual reasons.

But he jokingly said "If you're going to build, why not build a twin?" (I think implying that twins were safer.. again.. mostly out of ignorance and concern.. he's a good guy..)

Now, not trying to start a single vs twin debate or anything.. I realize costs being what they are, and safety records being what they are, singles are just fine.. but it made me wonder..

Has Van's ever considered offering a twin kit?

Price and time would be one big issue and why most people wouldn't want to make it.. but I have to think that'd be awesome..

Thoughts?
 
My first thought is that you can buy a huge selection of twins today for what you are going to spend on a RV-10 build. In fact, you could probably buy a nice Barron and several years worth of fuel for the cost of a new -10. The market is completely flooded with light twins, so what would make Van try crack into it?
 
How many twin kits do you think Van's could sell? My guess would be not very many. Total up every E/AB twin engine plane in the world and I think the answer will come to you.

Light piston twins are dirt cheap to buy, and for some very good reasons.
 
Toobuilder said:
My first thought is that you can buy a huge selection of twins today for what you are going to spend on a RV-10 build. In fact, you could probably buy a nice Barron and several years worth of fuel for the cost of a new -10. The market is completely flooded with light twins, so what would make Van try crack into it?
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As Michael says, there is not a market for a twin. Another issue would be most builders would not have the necessary training to fly a twin. Operating Limitations require the pilot to have the necessary FAA qualification to fly a homebuilt. Insurance would be another show stopper. Ever price insurance for a low time pilot in a high performance retract or twin? Typically the insurance company has higher requirements than the FAA.
 
RV6_flyer said:
As Michael says, there is not a market for a twin. Another issue would be most builders would not have the necessary training to fly a twin. Operating Limitations require the pilot to have the necessary FAA qualification to fly a homebuilt. Insurance would be another show stopper. Ever price insurance for a low time pilot in a high performance retract or twin? Typically the insurance company has higher requirements than the FAA.
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Ah this is the best response yet.. The insurance requirements didn't occur to me.
 
Hull insurance is optional.

A $15k annual maintenance bill and 25-35gph fuel burn are not.

...and this is why you can buy an "airworthy" Barron/Aztec today for what you have budgeted for your engine and prop on your -10.
 
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Tell your buddy about the old 80/20 rule. 80% of single engine accidents are walk-aways. Only 20% of twin accidents are.
 
Toobuilder said:
My first thought is that you can buy a huge selection of twins today for what you are going to spend on a RV-10 build. In fact, you could probably buy a nice Barron and several days worth of fuel for the cost of a new -10. The market is completely flooded with light twins, so what would make Van try crack into it?
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FIFY. I've flown Barons, C-310's etc. It's why they're so cheap... 28GPH adds up real fast, and unless you need to haul a lot of weight (or stroke your ramp ego) it just makes no sense.

That said, if I had the money and time, I'd be all over this thing. No Vmc, 12 GPH, 1000+ mile range, fast, comfortable.

http://www.velocityaircraft.com/airplane-models-vtwin.html
 
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DaleB said:
Total up every E/AB twin engine plane in the world and I think the answer will come to you.
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Does anyone make a viable twin kit? I don't think I've ever seen one. But just because no one is churning out twin kits does not mean there is no market for it. There was a time when no one was churning out single kits either and I think we'd all agree there was most definitely a market for it.

I agree the experimental twin kit customer would be more rare than the two seat single customer. But would that customer really be all that much more rare than say the customer who is willing to fly an airplane shaped like an insect, or an LSA with a single unreinforced tube for a wingspar, or a helicopter with rotors driven by v-belts?
 
The Velocity was on display at Sebring this year... sexy, Sexy, aircraft!
Good presentation at the above link as to how the brand eliminated or reduced many challenges facing twins.

... and there's your twin kit for anyone that wants to go that route.
 
The AirCam is a pretty successfull twin experimental kit. Just totally different than what most rv'ers think of.
 
For me, if I were to build a twin it would have to be something akin to a P38 or a Pond racer.. something silly sexy that I just enjoy to fly..

Practicality would go completely out the window.
 
I hadn't seen that velocity before. That ought to satisfy the experimental twin market quite nicely. I know I'd be in the market for one if I could find a way to afford it.

I'm still good with singles but the older I get, the less I enjoy the thought of what my options would be if I lost that single engine at night or over a low overcast or over Lake Michigan.
 
NOT to start a chute debate... but a forced landing in single over water, at night, would be a chute moment. Of course a twin that could actually fly on one motor world be even better.
 
The "RV-T"

RV-Twin
Smaller market for sure but I would order the kit today if available. Lets see 6 place, IO-360's...
 
Nothing between you and your RV-20 (a twin engine RV-10) but a little experimenting.

OK, who has the Photoshop image?

(that loud thunk was poor 'ole Van hitting the floor ;))
 
I was at an Oshkosh forum several years ago in which Van took questions. Someone asked about a twin, and Van talked about how complex it would be, and then told the joke about the function of the second engine on a twin....when the first engine fails, the second one gets you to the scene of the accident faster.
 
designrs said:
NOT to start a chute debate... but a forced landing in single over water, at night, would be a chute moment. Of course a twin that could actually fly on one motor world be even better.
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Chutes don't have the best track record when used over water. In the one Cirrus over water chute deployment I'm aware of, the single occupant suffered a serious low back injury on touchdown. Something to do with the fact that the landing gear are designed to crush on impact with the ground thus aiding in the deceleration process and they tend not to crush on impact with the water thus raising the g-loads on impact.

In that case the guy was lucky. There were people nearby that were able to help him out of the plane and into their boat before the plane sank. Had it happened miles from anyone, he may have drown.
 
Why is the velocity v-twin too expensive to build? If you can afford to quick build an RV-10 the velocity can't be too much more. The velocity v-twin kit price is for a quick build kit. Used engines would help with the cost too. Finding used Lycoming IO-540s is tough.
 
I would think the appropriate response we be, "Why would you want a twin?"

There are reasons, but I would guess his, and your, question was in regards to safety. There are more cost effective ways to achieve safety for the vast majority of operations than a redundant engine, which makes it really not worth it, IMHO.

Tim
 
Safety?

I believe that the most prevalent cause of engine failure is fuel starvation.
If one engine runs out of fuel, the other won't be far behind.
 
Just take your RV-10 and strap a pair of Rotax 914's either side of the nose. The weight and balance should come out pretty close to an IO-540. Cost should be comparable to a new IO-540 and you now have the advantage of a true 200HP upto FL160!

Jabiru did it with their J430.

Photo courtesy of Australian Aviation magazine.
Twin-22-of-671.jpg
 
The numbers for the Velocity V Twin look really impressive. The prototype has a pair of O-320's on it and yet it still performs well.

The problem with this and all canards is they take a long runway but with the V Twin being a pusher, they were able to put the engines close together and eliminate the asymmetric thrust issue experienced by most twins with one engine out. That and the "un-stallable" characteristics of the canard makes it a great cruising machine.

There is a guy who is building a twin out of an RV-6A. I don't think it has flown yet.

My only issue with a twin is it doubles your chance of an engine failure. That said, the Velocity V Twin sure looks like a nice plane!

One thing I really like about all the RV's is that if there is an airport depicted on a chart, your RV can land there. Well, as long as there isn't an "H" in the middle of the circle.
 
There is a twin RV8 under construction north of 38th parallel. I spoke with the builder two years ago very ambitious and impressive project. Insurance was the major roadblock as I understood it.
 
British twin kit

Don't recall the name, but it was two seat tandem, aerobatic. However, at a time when an RV-6 kit was $15, they wanted $100 for their kit. You can count the number of kits they sold on the fingers of one foot.
 
joe gremlin said:
Chutes don't have the best track record when used over water. In the one Cirrus over water chute deployment I'm aware of, the single occupant suffered a serious low back injury on touchdown. Something to do with the fact that the landing gear are designed to crush on impact with the ground thus aiding in the deceleration process and they tend not to crush on impact with the water thus raising the g-loads on impact.

In that case the guy was lucky. There were people nearby that were able to help him out of the plane and into their boat before the plane sank. Had it happened miles from anyone, he may have drown.
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I gather from your comment you have not seen or heard about this Coast Guard footage released last week of a Cirrus parachute deployment over water near Hawaii:
https://m.youtube.com/watch?v=gBCUQlF3MMU

It appeared to me to be a fairly benign touch down even in rough seas. The only thing that bothers me is how quickly the chute filled with water and drug the plane down. I would be more concerned with that issue especially if the chute drug the plane over on the open door side.
 
N941WR said:
My only issue with a twin is it doubles your chance of an engine failure.
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This is a common argument against twins and its lack of validity is easily established. The chances of an engine failure don't matter. What matters is the options you have available after a failure.

I always like to present the following scenario to twin nay-sayers. You and your spouse are on an island. Your spouse develops a strange illness and needs medical attention on the mainland ASAP or impending death could result. No ferries available, no boats to rent charter borrow or steal, no scheduled flights or charters planes available.

The airport operator has two planes he'll let you borrow. A single and a twin. But he warns you that both have wonky engines and it wouldn't shock him if either one had an engine failure in the next 40 minutes of flight. The mainland is a 90 minute flight. Assuming you're current and proficient in both singles and twins, which one you gonna take? I defy anyone to pick the single in that scenario.
 
joe gremlin said:
This is a common argument against twins and its lack of validity is easily established. The chances of an engine failure don't matter. What matters is the options you have available after a failure.

I always like to present the following scenario to twin nay-sayers. You and your spouse are on an island. Your spouse develops a strange illness and needs medical attention on the mainland ASAP or impending death could result. No ferries available, no boats to rent charter borrow or steal, no scheduled flights or charters planes available.

The airport operator has two planes he'll let you borrow. A single and a twin. But he warns you that both have wonky engines and it wouldn't shock him if either one had an engine failure in the next 40 minutes of flight. The mainland is a 90 minute flight. Assuming you're current and proficient in both singles and twins, which one you gonna take? I defy anyone to pick the single in that scenario.
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IMHO the trouble is that the majority of non- professional twin pilots do not maintain true currency. Those pilots are fooling themselves if they choose the twin.
 
Vlad said:
There is a twin RV8 under construction north of 38th parallel. I spoke with the builder two years ago very ambitious and impressive project. Insurance was the major roadblock as I understood it.
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The one in Virginia, or another one?
 
RVbySDI said:
I gather from your comment you have not seen or heard about this Coast Guard footage released last week of a Cirrus parachute deployment over water near Hawaii:
https://m.youtube.com/watch?v=gBCUQlF3MMU

It appeared to me to be a fairly benign touch down even in rough seas. The only thing that bothers me is how quickly the chute filled with water and drug the plane down. I would be more concerned with that issue especially if the chute drug the plane over on the open door side.
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Nope hadn't heard of it. Glad it worked out for the guy. Makes me wonder if Cirrus altered their design after the first guy got hurt. Seeing how quickly the chute drags the plane under, its really not the kind of situation you'd want to face with a back injury.
 
rmartingt said:
I'm just gonna leave this here...

Cri-cri-all-electric-airplane-flying-on-the-sea.jpg
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I heard a story, don't know if it is true, about a young guy who built one of these so he could get cheap multi time. The story goes that a Major hired him on the spot because he was smart in building his time with the Cri-Cri.
 
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BobTurner said:
IMHO the trouble is that the majority of non- professional twin pilots do not maintain true currency. Those pilots are fooling themselves if they choose the twin.
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The thing is, a lot of them are fooling themselves when it comes to currency in a single too.
 
If you are worried about the odds being twice as likely that you will have an engine failure because you have two engines then it would make sense that having zero engines would make it safer yet. :cool:

As far as building a homebuilt twin, I would like to see something along the lines of the old Wing Derringer. As I remember it they had two seats and two Continental GTISO 520 engines. Talk about single engine performance, I think that would do it. That would be like an RV 7 with two turboed 375 hp engines.
 
aerhed said:
Tell your buddy about the old 80/20 rule. 80% of single engine accidents are walk-aways. Only 20% of twin accidents are.
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It's important to note that this statistic only accounts for reported accidents. A single engine failure in a twin that then proceeds to land safely is generally not considered a reportable event.
 
Charles in SC said:
As far as building a homebuilt twin, I would like to see something along the lines of the old Wing Derringer. As I remember it they had two seats and two Continental GTISO 520 engines. Talk about single engine performance, I think that would do it. That would be like an RV 7 with two turboed 375 hp engines.
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The Wing Derringer had 160 HP on each side.
 
Autoreply said:
Quite a few people feel that with centerline trust, a light twin would be a good alternative.

2 VW's for a two-seater, or maybe two Rotaxes (Rotaii?)/ULpower 4-bangers for a 2+2.

Here is a lot more discussion:
http://www.homebuiltairplanes.com/f...ngine-push-pull-design-idea-beetlemaster.html

With an otherwise simple plane (fixed gear etc) that'd be something that might be in the same league as an RV in terms of operating cost and performance.
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I can't believe 5 hours went by and nobody else noticed...
Autoreply, welcome to VansAirforce!

I was also thinking about a twin kit. It would need 6 seats, and an option for 360's or 540's.

But then again, I know of a Baron on at the home field with two overhauled engines for less than the cost of a RV-10. Hmmm....
 
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You can have your twins....

My very first actual multi engine jet flight, we lost two PW615's in actual IMC at 32,000 ft. 423 hours since new. Shut the first one down as it lost oil pressure. The LH side lost oil pressure about 2 minutes later. It felt like I had swallowed a cup of concrete. We did get back on the ground. ATC got everybody out of the way and gave us a very large 270 onto the localizer before we hit the clouds and ice. At a break in the checklists, I told the Left seat I wished I was back in my rocket and twisting my own wrenches. His response was "I believe you." After much investigation it was written up as a computer glitch, however a few days later, the LH engine seized in flight ! (less that one flight hour later) Massive compressor stall as # 3 bearing welded itself solid, filling the cabin with smoke with the owner and his family on board.

You can have your twins. I'll take the RV 10 or the Rocket every time.
 
F1R said:
After much investigation it was written up as a computer glitch, however a few days later, the LH engine seized in flight ! (less that one flight hour later) Massive compressor stall as # 3 bearing welded itself solid, filling the cabin with smoke with the owner and his family on board.

You can have your twins. I'll take the RV 10 or the Rocket every time.
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What make & model jet was it?
 
rookie1255 said:
Why is the velocity v-twin too expensive to build? If you can afford to quick build an RV-10 the velocity can't be too much more. The velocity v-twin kit price is for a quick build kit. Used engines would help with the cost too. Finding used Lycoming IO-540s is tough.
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The kit itself is north of $110K.

Add two IO-320's (what it uses), props, and a panel... you're into it another $100K easy. Interior, building, etc... you'll be $300K before it ever moves under it's own power. It'll be a sexy $300K though.
 
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