What's new
Van's Air Force

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

Rv-4 wing on a RV-6???

J

jetdrivr

Member
Without having the plans for a -6 to reference, I am curious if any of you -6 guys can tell me if an un-assembled RV-4 wing would work on a RV-6 fuselage?

Overall wingspan is fairly close (I think?) but I suspect there would be some issues at the bulkhead area considering the width of the -6 vs. -4. Also, the wing would have to be cut down much like a Harmon Rocket to achieve the overall length considering the fuselage differences. I also know about the difference in fuel quantities but these all seem like fairly manageable obstacles to overcome....I think???

Is there some other really obvious or not so obvious, reason(s) why this would be next to impossible?


Thanks
 
Thanks

I thought I remembered something along those lines but couldn't find anything using the search criteria I had input. Thanks for the links and info.
 
X marks the spot!

Hi Mark!

Yes sir, I am flying an RV6 fuselage coupled with RV4 wings and tail. With the help of my late RV guru friend A.P; we re-jigged the 4 wings, removed 1 rib bay from the center section and matched the spars exactly like the RV-6 plans show. What we found were the wings are identical minus one center section rib bay. The horizontal required installing the RV-6 spar attach. The Rudder and Vertical are nearly identical on the 6 and 4, easy match. Fuel? Since the RV4 tanks were built and I was on a very tight budget, I installed RV4 wing tanks. My friends at Safe Air One (Hollywood and Cheese) installed a set of their tanks to bring the total to 41 gallons. Power is an 0-320A with MT FP 2 blade prop, Catto in works. Dimensionally the wings are 4" shorter overall and the empennage is 6% smaller than a stock RV6. I considered naming it the RV-5 but that airplane adorns Van's rafters at North Plains. Thus, the "RVX" was born.

It is a light, 150HP back to basics RV and flies very well. It exemplifies why I built an RV in the first place many years ago and what brought me back to this line of thinking. After owning a Harmon Rocket (and feeding it) for 6 years, the X is a breath of different and fresh air. I would be glad to answer any questions you might have off-line or on-line :)

Needless to say after 100 hours here are some observations.

1. Speed: It's easily 10 knots faster with 150HP than my stock 150HP RV4 was 15 years ago. Much of that could be my learning curve from owning my 4 and the attention to detail, rigging, fairings and fit and finish on the X. 177 Knots indicated at WOT 2000' MSL (GS backed up on GPS) I raced a Cirrus SR22 yesterday and was able to hang (not overtake)it no worries at 3500' MSL. Not bad for 150 ponies. Lands at 60 knots solo.

2. Handling: Much more sensitive in pitch and roll than a stock RV6.

3. Utility: Operates off my 1500' grass strip burning ethanol free MoGas.

4. Overall: Easily the most fun RV I have ever flown and very aerobatic.

Questions?

Smokey


The "RVX"
 
Last edited:
That is such a beautiful plane. I wish I had the skills, knowledge, and patients to build my own plane and do something like you did.

So, when are you going to start making RVX kits? :)

What are real world cruising numbers? Fuel flow, speed, RPM?

I've read a lot of your posts describing what it's like to strap into a Rocket, and I thought that someday, that's what I want. But then you write something like this about the X. And my wife has already said there's no way she's sitting behind me.

I guess it's a good thing I have lots of time to think about it!

Steve
 
Last edited:
Smoky,

What is the RVX's empty weight?

I find your comments very interesting after coming back from a Rocket.

My RV-6 weighed in at 1025lbs. With 160hp and Sensenich prop I see 158kts true at 5000' at 70% power. I am very pleased with its performance in every respect but I have nothing to compare with.

Doug Gray
http://bypass.dyndns-free.com/
 
RV-6A Wingspans

I have stock wings on my RV-6A but I have several modifications that give different fuel capacity & wing spans:

1. Flat Metal tips (no tip plates) = 38 gallons & 21'
2. Semi-flat fiberglass tips = 38 gallons & 21.25'
3. One flat metal tip and one 3" streamlined tip = 38 gallons & 21.25'
4. Streamlined 3" tips = 38 gallons & 21.5'
5. Streamlined 3" tips and tip tanks = 55 Gallons & 23'
6. Stock tips and tip tanks = 55 Gallons & 24.5'

The 4" shorter span in itself will not be a problem I suspect. I found configuration 4 in my experiments to be the fastest and most maneuverable. It does takeoff, climb and land well but differently than stock as you would expect.

Bob Axsom
 
The X....

Hi Doug, Steve,

The X weighs in at 945 lbs empty with 0-320A (150 ponies) and wood/composite MT prop. Minimum panel, no interior, lithium battery, Lexus starter/alt. I learned from Bob Axsom's "notes for knots" alot about cooling drag and fairings and made mine fit tight. I also rigged it better than any of my RV's yet.

Cruise speeds at 2500' MSL 75 degrees OAT
2000-128 Knots TAS 5.5 GPH (my favorite)
2100-137 Knots TAS 6.2 GPH
2200-140 Knots TAS 6.6 GPH
2300-148 Knots TAS 7.1 GPH (Acro setting)
2400-155 Knots TAS 7.9 GPH
2500-162 Knots TAS 8.8 GPH
2600- 168 Knots TAS 9.4 GPH
2700 175 Knots TAS 9.8 GPH

The best part is plopping down on my 1500' strip at 55 Knots indicated.

Amazingly enough my Rocket's numbers were 180 Knots TAS at 10.5 GPH at 8500'. It however got worse as you went faster. The X can burn much less fuel at the slower end of the spectrum. It's what I really missed about my RV4, not the high end, but the low end. Thus, the airplane of my future is the airplane of my past. :)

Smokey
 
Last edited:
So, let me ask you. If you were to put a light weight CS prop on it, what kind of difference would it make? Would you be able to get more speed out of it, without extra fuel burn?

Or is the price not worth the gain?

Steve
 
Smoky,

945 lbs is seriously light. Well done!

I was pleased with 1025 especially when my hangar mates RV-6 weighed in at 1150lbs on the same calibrated scales.

My heavyish items are:
Concorde RG25XC Battery +18(lbs extra),
Sensenich (metal) Propeller +18,
Polyester versus Epoxy Cowling +15,
Polyester versus Epoxy Wingtips +8
EFIS +3
SportsmanSeats (versus simple foam) +10
Extra wire +1
Lexus Starter/Generator +5

I conceed 78 lbs on these items plus the savings in wing span for the -4 wings. They sure add up quickly. Most of this weight saving is forward of the CofG so your comments about pitch sensitivity are not such a surprise.

Tell me more of your Lithium Battery and the Lexus Starter/Alternator.

Doug Gray
 
Hi 91t
I installed an MT constant speed prop on an RV3 which had a wood prop.

Rate of Climb about tripled, top speed increased by 1 knor,

I think it all depends on whether the fixed pitch prop is set up for climb or cruise.
 
Interesting...

Hey Smokey,

Glad you chimed in on this one. I am very impressed with your RVX. I initially posed the question because I have someone who wants to put a set of RV-4 wings I have for sale (soon) on his RV-6 and he wasn't sure if it could be done. Of course, the magic of this forum produced results within minutes.

That being said....I am about to embark on a Harmon/F1 Rocket for myself (similar to Vince Frazier's beautiful example). I would be very interested in chatting with you sometime since you have gone full circle, so to speak, about the pros/cons of the high horsepower world of Van's aircraft.

Parts have been purchased but nothing has been built as of yet. Still a little undecided on whether or not it is worth the time and money for the extra horsepower.

Mark

ps. PM sent as well.
 
Can you hear me now....

Hi Mark/Doug,

PM received and replied to, thanks!

As far as weight of the X, some items really help. 0-320A ND is lighter as well as the MT FP prop. The air-boaters down here use an after market Lycoming starter ring gear that is very similar to the new light weight version on the IO-233. I have one and it is a couple of pounds lighter. Mags are heavy compared to the EI system I have on one side, couple of pounds there. No Vacuum pump or associated lines, filters, what have you. Lithium aircraft battery. www.lithiumaviationbattery.com very light. Mounted on firewall saves weight in wires. No interior, Stock Car cool-mat firewall insulation and Enigma EFIS, all very light. Two total coats of paint. One primer, one color and single stage.

As far as prop performance goes, your mileage may vary. In the early RV days, very few people installed C/S props as they were heavy and expensive. Prop makers like Bernie Warnke and later his daughter Margie as well as Gary Hertzler and later Craig Catto worked hard to develop composite FP props to deliver a "narrow RPM range" or "almost constant speed" if you will. I ran Margie's, Bernie's and Gary's props on my RV4 and later CC's. Bernie's and Margie's wood/composite overlay props are not only works of art but simply amazing with a 350 RPM spread between full power climb and max cruise. Margie's "Claw" being the best ever. However, the MT prop on the "X" matches those exact numbers, a testament to German engineering. A plus is leading edge protection, a must down south. Craig Catto is building me a nice 2 blade with nickel leading edge protection to test, I will post those numbers when I install it.

Like page one in my old RV4 builders manual states "Keep it light, simple and straight, it will reward you with exceptional performance for a modest price".

Smokey
 
Last edited:
smokyray said:
Hi Mark/Doug,
The air-boaters down here use an after market Lycoming starter ring gear that is very similar to the new light weight version on the IO-233. I have one and it is a couple of pounds lighter.
Smokey
Click to expand...

Smokey can you post a pic? I have had the same idea to machine lightening holes in a stock flywheel to lose a few lbs. and to make servicing the Electroair crank trigger pickup a whole heck of a lot easier. I've looked at the IO-233 flywheels and figured there's no reason not to do the same to a stock Lycoming flywheel.
 
Roger Dodger...

Hi Bob,

Wilco, pictures to be taken next oil change! BTW, how did your RV fare at SNF? I was very fortunate, and blessed. No damage.

Smokey
 
Smokey mine was the one that had Sleepy's RV-3 on top of it. Fuselage was completely crushed, right wing had one ding in it. Insurance company totalled it and I bought it back from them and by the end of today should have a new QB fuselage on order. I'm cannibalizing a lot of parts from the damaged fuselage. Van's has given a very nice discount on parts for anyone that had a damaged airplane at SNF and am eternally grateful to them for doing that.

Originally I thought the fuselage was repairable but there was a bit more damage done to it by Atlanta Air Salvage, who disassembled the airplane and stored it for the insurance co. That's another story...
 
Always looking for a way to save another couple of pounds

smokyray said:
Hi Mark/Doug,

PM received and replied to, thanks!

As far as weight of the X, some items really help. 0-320A ND is lighter as well as the MT FP prop. The air-boaters down here use an after market Lycoming starter ring gear that is very similar to the new light weight version on the IO-233. I have one and it is a couple of pounds lighter. Mags are heavy compared to the EI system I have on one side, couple of pounds there. No Vacuum pump or associated lines, filters, what have you. Lithium aircraft battery. www.lithiumaviationbattery.com very light. Mounted on firewall saves weight in wires. No interior, Stock Car cool-mat firewall insulation and Enigma EFIS, all very light. Two total coats of paint. One primer, one color and single stage.

As far as prop performance goes, your mileage may vary. In the early RV days, very few people installed C/S props as they were heavy and expensive. Prop makers like Bernie Warnke and later his daughter Margie as well as Gary Hertzler and later Craig Catto worked hard to develop composite FP props to deliver a "narrow RPM range" or "almost constant speed" if you will. I ran Margie's, Bernie's and Gary's props on my RV4 and later CC's. Bernie's and Margie's wood/composite overlay props are not only works of art but simply amazing with a 350 RPM spread between full power climb and max cruise. Margie's "Claw" being the best ever. However, the MT prop on the "X" matches those exact numbers, a testament to German engineering. A plus is leading edge protection, a must down south. Craig Catto is building me a nice 2 blade with nickel leading edge protection to test, I will post those numbers when I install it.

Like page one in my old RV4 builders manual states "Keep it light, simple and straight, it will reward you with exceptional performance for a modest price".

Smokey
Click to expand...

Smokey,

Since reading this post I have become seriously interested in the lithium battery for weight savings. What size do you have, what voltage are you charging at, and lastly, how long have you had the lithium battery?

I would also appreciate advice on how to find one of the light weight ring gears you mentioned. I have looked at several of the airboat forums but haven?t found any specific information.
 
Smokey,

Love those numbers and I'm a fan of the "back to basics". I'm now flying an RV-8 with a 150hp and wood prop. I still have a full set of steam gauges so my weight is a little higher but it looks like we fly the same (power, speed, fuel burn).

Nice plane!
 
rocketbob said:
Smokey can you post a pic? I have had the same idea to machine lightening holes in a stock flywheel to lose a few lbs. and to make servicing the Electroair crank trigger pickup a whole heck of a lot easier. I've looked at the IO-233 flywheels and figured there's no reason not to do the same to a stock Lycoming flywheel.
Click to expand...

If you are going to do that, then just machine off the pulley also (more weight loss) and move the alternator (SD type) to the VAC pad? And no belt or broken arms to deal with.
 
You must log in or register to reply here.
Back
Top