What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

What the heck is this RV-8A Twin Engine

I spoke to the builder about 3 years ago or so. She was showing me the project it's incredible how much thought and labor she put into it. Marvelous engineer! Congratulations on first start and taxi Bobbi!
 
That is pretty interesting.
I wonder what the Vmca will be. The stock 8 tail seems small for a twin but the fixed gear helps.
I would love to see it some day.
 
http://theplanedoctor.com/images.php

(Scroll down to Duo Deuce)

It appears to be an RV-8 fuselage (not -8A; note the gear towers in the forward cockpit), Twin Comanche engine nacelles and cowlings, RV8A nose gear and mount, and some sort of fastback mod and side-hinge canopy. I can't tell what main gear they're using, but it looks similar to PA-28 kit.

All in all, a pretty ambitious project; I'm surprised we haven't heard about it earlier.

This is similar in many respects to the Twin JAG discussed earlier, but probably comes with enough power to guarantee a reasonable single-engine service ceiling.

Thanks, Bob K.
 
Bob Kuykendall said:
http://theplanedoctor.com/images.php

(Scroll down to Duo Deuce)

It appears to be an RV-8 fuselage (not -8A; note the gear towers in the forward cockpit), Twin Comanche engine nacelles and cowlings, RV8A nose gear and mount, and some sort of fastback mod and side-hinge canopy. I can't tell what main gear they're using, but it looks similar to PA-28 kit.

All in all, a pretty ambitious project; I'm surprised we haven't heard about it earlier.

This is similar in many respects to the Twin JAG discussed earlier, but probably comes with enough power to guarantee a reasonable single-engine service ceiling.

Thanks, Bob K.
Click to expand...

Bob, I think the -8A retains the gear towers, less weldments, IIRC.
I think the fin is so small that the Vmc might be close to Vne. (sort of being sarcastic, but it is a serious concern. )
 
Airventure racer

Bobbi is an A&P and has her own shop in VA. Met her several times racing in the Airventure Cup race. She flew her RV-4 in the race. Interesting lady. That plane sure should go like **** but I worry about that nose gear
 
Bob Kuykendall said:
http://theplanedoctor.com/images.php

(Scroll down to Duo Deuce)

It appears to be an RV-8 fuselage (not -8A; note the gear towers in the forward cockpit), Twin Comanche engine nacelles and cowlings, RV8A nose gear and mount, and some sort of fastback mod and side-hinge canopy. I can't tell what main gear they're using, but it looks similar to PA-28 kit.

All in all, a pretty ambitious project; I'm surprised we haven't heard about it earlier.

This is similar in many respects to the Twin JAG discussed earlier, but probably comes with enough power to guarantee a reasonable single-engine service ceiling.

Thanks, Bob K.
Click to expand...

Thanks Bob.
 
Another thought is how / if the wing spar was modified. Stress on the spar will be in the opposite direction.
 
I'm curious if she strengthened the tail or did any other mod to prevent flutter. Between the tail and the nose wheel (and the rest of the plane for that matter), I hope she did the necessary engineering homework. Cool though I suppose.
 
1001001 said:
Wow, you're not kidding, as far forward as those nacelles appear to be.
Click to expand...

Looks can be deceptive. As I recall, the Twinkie uses an extended-hub prop to accommodate the long pointy cowling; the engine itself is pretty far back.

I agree with Steve Smith that the vertical tail area might be a bit on the small side for engine-out operations, but I think it is going to be a ripping fast airplane.
 
rvbuilder2002 said:
Nope.

The RV-8A has a different fuselage for the portion that is fwd of the wing spar center section.
Click to expand...

Oh I see now, there is still an F-802 bulkhead that is shaped kind of like one face of the gear tower, but the box is not there. Is that right?

In addition to the likely too small a rudder, a friend reminded me that there are large unsteady forces from the nacelles into the wings. They need to be very torsionally stiff to prevent whirl flutter. Assuming the fuel tank has been moved outboard, the forward connection between the fuselage and wing would need a lot of beefing up. Some pretty serious engineering needed to keep this airplane safe.
For those worried about the nose wheel, remember that the c.g. needs to end up in the same place with respect to the wing, so the nose wheel loads should stay about the same (except for the increase in gross weight). It may take some ballast in the back to get the c.g. right -- probably a huge battery mounted fairly far aft.
 
Last edited:
Center section

appears to be modified. Hard to tell from the picture(s), but there could be a lot of added structure hidden there. Kind of reminds me of the Winged Derringer.

A lot of innovative thinking displayed here.
 
Weasel said:
Tandem seat twin......that unique
Click to expand...

What about the Phillip's Speedtwin.
There were plans to put it into production, but that seems to have gone quiet.

1417327.jpg
 
scsmith said:
For those worried about the nose wheel, remember that the c.g. needs to end up in the same place with respect to the wing, so the nose wheel loads should stay about the same (except for the increase in gross weight). It may take some ballast in the back to get the c.g. right -- probably a huge battery mounted fairly far aft.
Click to expand...

True, but. With two engines, hopefully some structural strengthening, this plane is significantly ficantly heavier and therefore will have more weight on the nose as well.
 
Anybody brave enough to post it on The Mothership's FB page?!? :D Probably give Van a bloody heart attack!
 
Are there other twins without nose wheel steering? Seems you would be pretty vulnerable at low speeds with a power loss.
 
jimgreen said:
Are there other twins without nose wheel steering? Seems you would be pretty vulnerable at low speeds with a power loss.
Click to expand...

I flew S-2 Trackers for 4 years. 1500 hp a side, with no nose wheel steering.

If you lose power while still on the runway, you pull both throttles back and stop. You probably won't be able to taxi on one engine, but so what.
 
Douglas 26

jimgreen said:
Are there other twins without nose wheel steering? Seems you would be pretty vulnerable at low speeds with a power loss.
Click to expand...

The Douglas 26 Bomber ( 2 of P&W R2800-2000 HP per side!) had a free castering nose wheel. When Air Spray used these for water bombers they found that tail wheel pilots had a much easier time / higher confidence on take off, landing and ground handling.
 
Last edited:
Among RVs, the tailwheel models have tailwheel steering but many large multi-engine tailwheel airplanes do not and it can be difficult to taxi on one engine. Kevin's story reminded me of watching a DC-3 land one day with an engine out. They were not able to taxi in either and had to leave the airplane on the runway.
 
Twin -8

What a terrible shame after that effort and innovation. The fact that she had no life-threatening injuries is wonderful news.
 
Ouch, that's too bad. Looks like that long nose cone absorbed a fair share of the impact as it went over.
 
Are there other twins without nose wheel steering? Seems you would be pretty vulnerable at low speeds with a power loss.
Click to expand...

There are. Here's one - North American B-25
 
You must log in or register to reply here.
Back
Top