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RV-Twin

smenkhare

Active Member
has Vans ever considered a twin engine kit?
i've seen a couple of other kit manufacturers working on them and think a vans would sell quite well.
 
Kills the total performance idea. Why do you need the second engine? Just get a bigger first engine. I don't think (personally) that this is on Van's list of things to do...

Now a Fiberglass Twin Comanche (Ravin) would be cool :).
 
I'm pretty sure it took a lot of arm twisting to get Van to make twin SEAT airplane, nevermind twin engines. Honestly, I never thought I'd live to see a 4 seater come out of Vans so anything's possible, I guess.

Here's an interesting question. If you have 1 propellor driven by 2 engines via some sort of gearbox, is that a twin or a very funky single? I'm not suggesting anyone do this but I am curious how that's classified. I could make a good argument that the two engines coupled with gearbox is no more 2 engines than 6 pistons coupled with a crankshaft is 6 engines.

There must be a governing regulation somewhere but I couldn't find it.
 
jcoloccia said:
I'm pretty sure it took a lot of arm twisting to get Van to make twin SEAT airplane, nevermind twin engines. Honestly, I never thought I'd live to see a 4 seater come out of Vans so anything's possible, I guess.

Here's an interesting question. If you have 1 propellor driven by 2 engines via some sort of gearbox, is that a twin or a very funky single? I'm not suggesting anyone do this but I am curious how that's classified. I could make a good argument that the two engines coupled with gearbox is no more 2 engines than 6 pistons coupled with a crankshaft is 6 engines.

There must be a governing regulation somewhere but I couldn't find it.

i believe that's classified as a single.
ayres was working on one for fedex as a caravan killer before they went bankrupt.
 
I had the hots for the Phillips Speed Twin many, many years ago. All metal, two O-200s, tail dragger, two-seat tandem, aerobatic. Something like an RV-8, with the same power but split into two engines. There was an article in Sport Aviation that said that the designer was going to produce a kit. But he died before that could happen.
 
Helicopter twin

jcoloccia said:
Here's an interesting question. If you have 1 propellor driven by 2 engines via some sort of gearbox, is that a twin or a very funky single? I'm not suggesting anyone do this but I am curious how that's classified. I could make a good argument that the two engines coupled with gearbox is no more 2 engines than 6 pistons coupled with a crankshaft is 6 engines.

Helicopters with twin turbines and one propellor (rotor) are classified as twins. When one engine stops the remaining functioning engine does not have to drive the dead engine.
 
jcoloccia said:
Here's an interesting question. If you have 1 propellor driven by 2 engines via some sort of gearbox, is that a twin or a very funky single? I'm not suggesting anyone do this but I am curious how that's classified. I could make a good argument that the two engines coupled with gearbox is no more 2 engines than 6 pistons coupled with a crankshaft is 6 engines.

I belive Soloy was working on such a contrivance several years ago. Two PT-6s mated together, driving a single propeller shaft. Called it a "TwinPack", I think. Not sure why it never saw the light of day.

If something like that ever made it to the flying public, I doubt (or should I say "hope logic would prevail at the FAA") you would be required to have a Multi-Engine Rating to fly it. The purpose of a MEL is to ensure you are aware of and can handle the unique flying characteristics encountered when a multi-engine airplane loses one of its engines. You have none of those unique characteristics in an airplane of they type you're describing.
 
jcoloccia said:
I'm pretty sure it took a lot of arm twisting to get Van to make twin SEAT airplane, nevermind twin engines. Honestly, I never thought I'd live to see a 4 seater come out of Vans so anything's possible, I guess.

Here's an interesting question. If you have 1 propellor driven by 2 engines via some sort of gearbox, is that a twin or a very funky single? I'm not suggesting anyone do this but I am curious how that's classified. I could make a good argument that the two engines coupled with gearbox is no more 2 engines than 6 pistons coupled with a crankshaft is 6 engines.

There must be a governing regulation somewhere but I couldn't find it.

It depends on HOW the "gearbox" works.

There was an aircraft intended to be a "production" aircraft built a few decades ago with two (turbine?) engines turning a single pusher prop. The prop was high tech kevlar (fairly new at the time), and the gearbox was set up so that if one engine failed it "dropped out of the loop" and so did not create drag on the remaining engine.

They got FAA approval to call it a multi-engine centerline thrust design. I don't think they ever made it into production, or if they did they only built a few.
 
Any old timers remember Van's April fools joke back in the late 80's? He published an article in the RVaitor about a twin fuselage RV-4 concept, similar to the P-82 twin mustang. There was a drawing of it along with a report on a stealthy fact finding trip to the CAF to look at the P-82. The give-away was that he said they flew down to Arlington in a C-172 (if I recall correctly.) I think the twin RV-4 was going to be called the RV-8. Lot's of guys thought it was serious and it took a while to straighten everyone out.

Wish I still had that RVaitor issue. It went with the plans and manual when I sold my kit.
 
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Phillips Speed Twin

Thanks Kevin for the Phillips Speed Twin picture. An RV-8 version of that craft would look amazing. Perhaps a 912 or 914 hung off of each wing? (that rotax statement is bound to generate some opinions :D )

Stan
 
If you do find that RVaitor take a look at the date on the drawing. It's April 1st.
 
A friend of mine in the military flew Blackhawks and they have a two engine one rotor configuration. When he got out and was looking for flying jobs he found that all his time in the hawk would be considered single engine time as it only has one propulshion (sp) unit. And on top of that his 1500 hrs in type is questioned by some places as it is not a certified aircraft either!!! Military aircraft are not certified aircraft, probably better. He eventually found a job in the DEA flying blackhawks chasing drug runners down in the islands.
 
I can't find a single performance twin kit currently available on the market. If Van's wants to work on something after the RV12, they would have the whole market to themselves.

I'm thinking a push pull 4 seater like the Adam with 0-360s (I'd substitute Subes of course) :rolleyes: and pressurized please so I don't need to suck on O2. Might cut into Cirrus and Lancair sales a bit plus open the whole twin market. I'd sell my other 2 RVs in a second to build one of these.

Ken and Van must be looking for something more challenging to design by now. :rolleyes:

I'd even take fixed gear but need a 250 knot Vne. :)
 
Hensley

The only thing close is Hensley's project. I have talked to them numerous times and I have all sorts of doubts about whether it will ever fly.

There is also a fellow in Nashville who has a 337/O-2a related "kit". It uses a carbon body and 337 wing I think. See www.aviationenterprises.us
 
Twin engine design driving one prop... first to come to mind is the Learfan. Dual engines geared to one pusher prop. It was also made of all carbon fiber in the 70's. One great looking plane. I believe several were made, however it never recieved certification due to Bill Lears death.

Mike
 
Lost performance

If you want total performance then a twin is not viable.

You don't gain much for the extra fuel burn in a twin.

If you compare, for example, the speed and payload of a 285HP Bonanza with a Baron with TWO 285HP engines you gain maybe 20KTs and a bit of payload. You need twice the fuel which means you need a bigger wing to lift the extra fuel and the weight of the second engine which means more drag.

The big advantage of the twin over the single is the difference in performance with one engine failed............ but then you have twice the chance of an engine failure.
Pete.
 
twin eng

about 8 yrs ago two bros. from argentia put two izusu 100 hp engines in a cozy and flew it to sun-n-fun across atlantic ocean i think 2 years in a row
they were machinest and talked about selling a system like in the cozy that drove the single prop never heard anything as to outcome
 
n468ac said:
It would be nice to see a 300kt airplane out of Van's ... maybe a modified 7 or 8
Best try, the -10 would need a freakin PT-6 to got 300kt's. But you'd need a composite wing to do it, or at least a Evo like wing. I'd like to build a -7 with a evo wing and a IO-540... :p. Not 300kt's, but hopefully cruise above 200kt's with any luck. Need to push the Vne a little during flight testing... doable? maybe.
 
fodrv7 said:
The big advantage of the twin over the single is the difference in performance with one engine failed............ but then you have twice the chance of an engine failure.
Pete.

My MEL instructor told me that in most light twins, the second engine is only there to carry you to the crash site after the first one quits.
 
The second engine has nothing to do with cost figuring you'd be burning 20 gal./hr., say 50% more than an RV10. Has to do with flying over the Rocks with more safety. With centerline thrust and a good power to weight ratio, losing one doesn't require too much action other than feathering the bad prop.

I'd be happy with a 240 knot cruise at 18,000. :)
 
smenkhare said:
heh.
that's the reason i asked.
apparently they stopped working on it a year or two ago :(

Heard that without a feathering prop the engine out behaviour of the Gemini was less then ideal :)
 
matt said:
Heard that without a feathering prop the engine out behaviour of the Gemini was less then ideal :)

That's true of many twins. Unless you properly bank into the good engine, close the cowl flaps, go to high RPM, feather the prop, precisely hold the proper airspeed and whatever else the POH says to do, many twins won't even maintain their altitude. In general, you're doing pretty good if you get a 100 or 200 fpm climb when you've done everything perfectly.
 
jcoloccia said:
That's true of many twins. Unless you properly bank into the good engine, close the cowl flaps, go to high RPM, feather the prop, precisely hold the proper airspeed and whatever else the POH says to do, many twins won't even maintain their altitude. In general, you're doing pretty good if you get a 100 or 200 fpm climb when you've done everything perfectly.

True. But apparently the Gemini took it to the next level. :D
And that is to bad because I really like it.
 
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jrsites said:
My MEL instructor told me that in most light twins, the second engine is only there to carry you to the crash site after the first one quits.

Funny old joke, but maybe time for a more serious or experienced instructor. After having had real-life engine failures in twins,- when people ask if I've ever had an engine-out emergency, my answer is, "No, I've just had engine-out situations."
 
captainron said:
Funny old joke, but maybe time for a more serious or experienced instructor. After having had real-life engine failures in twins,- when people ask if I've ever had an engine-out emergency, my answer is, "No, I've just had engine-out situations."

Even seen seriously there is no guarantee that a second engine improves safety. Actually, if you study statistics you will see that a twin is not safer then a single engine aircraft. There are a lot of reasons why we can question that statistical fact but from my MEI point of view one major problem is:
Two engines -> twice the chance of in flight engine failure -> twice as many chances of messing up an engine out situation
There is no question a twin in the hands of a proficient pilot is safer then a single engine aircraft. One of the problems with light twins is that too many pilots are not.
 
captainron said:
Funny old joke, but maybe time for a more serious or experienced instructor. After having had real-life engine failures in twins,- when people ask if I've ever had an engine-out emergency, my answer is, "No, I've just had engine-out situations."

It was his way of illustrating that you have to take a piston twin seriously, and that in many ways the second engine made the airplane MORE dangerous, rather than safer. It was his way of pointing out that in many piston twins, if you lose an engine and don't do EVERYTHING right, and quickly, that second engine is actually going to do you more harm than good.
 
Light twin reality

jrsites said:
It was his way of illustrating that you have to take a piston twin seriously, and that in many ways the second engine made the airplane MORE dangerous, rather than safer. It was his way of pointing out that in many piston twins, if you lose an engine and don't do EVERYTHING right, and quickly, that second engine is actually going to do you more harm than good.

I agree completely. I owned a B-55 Baron for 8 years. Wonderful airplane, reasonably fast and would haul 4 people in comfort. The cost of operation was almost twice that of a similar Bonanza but the speed was only about 10% more. I went to SimCom in Scottsdale evey year for simulator training even though I was flying for a living at the time. The cost of staying really current in the thing was a little over $3k a year. I can fly my RV8 a long way for $3k, thank you.

John Clark
RV8 N18U
KSBA
 
As I stated earlier, an engine-out in a twin can be an emergency depending on how it's handled, or simply a "situation". What would an engine-out in a single usually be considered? Seems absurd, thinking that a good engine putting out several hundred horsepower is somehow undesirable. This configuration has gotten many pilots safely to the runway of their choice. What is your plan when the engine quits in your single under EVERY conceivable flight and weather condition? Luck and prayers are good; Luck, prayers and an extra engine are better!
 
Concept pic for a Vans Twin

This thread inspired me yesterday, weather was way too nasty to work on real airplanes. So i thought i would try my hand at aerospace engineering.
I took a pic of a 7 i use for designing paint schemes for my customers. Little tweaking here and there, and The RV14 TW with sliding canopy. If this airplane is ever built. I want to paint the first one!!!
TV14Top.jpg

TV14Side.jpg

I reduced the size of these, so as to not take up too much server room
:p
 
I was sick enough to look at modifying a 7A airframe to take twin 120hp Suzuki Swift 1300cc turbo inline fours a couple years ago. Looked at spar structure and mods to hang the engine out there, nose mods, C of G... The more I delved into it, the more complex it became. Hmmm. not worth it for 10 knots really but it would have been one of a kind... I ordered the RV10 kit instead.

I really like the idea of a centerline thrust twin like the Adam A500 to reduce all those nasties with wing mounted engines. The old P337s were pretty decent on one engine at altitude but we'd need a low wing design of course.

Van's could lead a whole new market here in the experimental world...

If they won't build this, how about a fast, retractable single with high cruise (240-250 knots) rather than total performance as the main focus. There are few metal experimentals to choose from for us composite challenged rivet bangers. Turbo 540 Lyco (LS-2 type engine for me) and pressurized.

:cool:

I'm tired of Lancair guys with their noses in the air, leaving me in their dust. Eat iron er aluminum buddy!

Ok snapping out of my dream now. Back to work on my roll servo installation. :(
 
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Retract?

I think there was a twin 2-place a/c marketed in the 70s called the Derringer. Didn't sell well if I recall.

Altering your topic just slightly, I've wondered a few times if Vans ever considered a retractable.

A retract rv-7 would be genuine speed burner (but I'm guessing might be too heavy and clumsy).
 
Captain Sacto said:
A retract rv-7 would be genuine speed burner (but I'm guessing might be too heavy and clumsy).
Not really. There have been a few retract RVs built over the years. There was an article in Kitplanes a couple of years ago about a retract -4 in Germany. Bottom line was 100+ lbs of stuff (100 lbs less usefull load) for a very few extra knots.

A properly faired fixed gear is not all that draggy, at RV speeds.

Plus, can you imagine the insurance on a retract RV-X?
 
sprucemoose said:
There have been a few retract RVs built over the years. There was an article in Kitplanes a couple of years ago about a retract -4 in Germany. Bottom line was 100+ lbs of stuff (100 lbs less usefull load) for a very few extra knots.

A properly faired fixed gear is not all that draggy, at RV speeds.

f I remember right from that article the guy had built two -4, one RG and one fixed almost identical except for the gear and the speeds was within +- 1 knot..

Sounds like a lot of work for "nothing". But if anyone wanna go at it, there is a RG -4 project on sale over at barnstormers.
 
Another thing that he didn't mention in the article is that he had to move the fuel tanks farther out on the wings making the lateral balance much more critical.
 
RV RG

I hangared with the builder of the first RG Rv4. He claimed an extra 10mph, but wieght overcame any advantage in his mind. It performed very poorly. There was a complete set of very nice tooling for making the ribs, however, dust and time and the plans lost for lack of any interest. He passed away last summer, so not sure what came of all of the tooling.
 
Captain Sacto said:
I think there was a twin 2-place a/c marketed in the 70s called the Derringer. Didn't sell well if I recall..

I believe the complete name was "Wing Derringer". Pair of O-320. Only 5 built IIRC, and as the fates would have it, one is owned locally (Sacramento area) by a guy who also has a RV_3 in his collection.

http://www.probertencyclopaedia.com/IXW37.HTM

Mike
 
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Mike S said:
I believe the complete name was "Wing Derringer". Pair of O-320. Only 5 built IIRC, and as the fates would have it, one is owned locally (Sacramento area) by a guy who also has a RV_3 in his collection.
I did one flight in a Wing Derringer at Mojave a few years ago. Its O-320s had been replaced by O-360s. I was expecting it to be quite the performer, but I was very disappointed. It probably had lower performance than an O-360 powered RV-6.
 
Someone on here a while ago had a photo shoped pic of a p-82 rv-82 thing. It was two rv-8 fuselages with a center wing between the two and a twin tail I think, It was a cool pic and looks possible to me. Besides I love a mustang so why not a twin mustang. I heard a rumor that some of the reno race guys are putting a p-82 back together and should be flying soon...anyone confirm that? If its true it will be something to see and hear.
 
OK, how about modifying an RV with two engines on the wings and keep the fuselage engine! Three engines could give you way more load capacity. Of course you'd need extra fuel and a larger fuselage and wing, and it has to all metal, fixed gear to be a real RV....might look something like this
 
Nope

jsherblon said:
OK, how about modifying an RV with two engines on the wings and keep the fuselage engine! Three engines could give you way more load capacity. Of course you'd need extra fuel and a larger fuselage and wing, and it has to all metal, fixed gear to be a real RV....might look something like this

Wing is on the wrong side.

Mike
 
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