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Upgrading the 6.

S

speedbird

I'm New Here
Hi everyone, I am fairly new to this forum but have been lurking around for a while...
(one shouldn't underestimate the power of old fashion Procrastination) ;-)
I am about to purchase a 6 kit with wings and tail completed, Fuselage and the rest remains.
I wonder if anyone now about the possibility to put the Roncz) wing on the 6 instead for better mileage and cruise economy?
I see that some of you already have upgraded to the tail and firewall forward from the 7.
What else is "recommended" upgrades?
Guess at this stage I could go in almost any direction but hope to find a "proven" one...
Ideas anyone?
Blue Skies & Tailwinds
 
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Confused

The ronce aerofoil is filled to the 9..... it is not compatible with the Rv6 fuselage, the spar attachments are different.

Sixes eventually got the 7 balanced rudder.... I won't go into the reasons why as it will just start and argument. The original rudder works fine but for a number of reasons I would go to the 7 rudder.

Why would you want to build another set of wings anyway at great expense in time and money. The 6 is a great aeroplane and aerobatic with the original wings, the nine wings are not.

Build it to plans (maybe with the 7 Fin and rudder), and build it light.
 
Dear Steve, Thanks for the replay!
Then it is as I suspected...I hoped it was possible to replace the wing with replacement of the spar attachments too, because I haven't started the Empenage build yet, and maybe I should abort the purchase now...
The whole reason for not go with the original wing is economy. Smaller engine less fuel but still god numbers.
The original wings are already built, but not by me, (I am possibly buying a partly built kit)
Therefor I started to think about replacing the Wings, if it had been done before.
Guess it will not happen now.
Is the 7 rudder a bolt on as is when completed or does it need more "tweaking"?
Thanks for the info!
Cheers!
 
The 6's wing is just fine for speed and economy. I have a 160hp O-320 and have seen as much as ~ 200 mph (174 knots) true airspeed in level cruise at 7500-8500 MSL burning 8.9 gallons per hour. This was with a full load of camping gear in the baggage area too. When I'm just out flying around for fun, I throttle back to about 2100-2200 rpm and still go 140-150 mph on 5.3 GPH.

The original stock, short -6 rudder is also a good one too. It's not counterbalanced, but doesn't need to be either. There is no danger of flutter at the published Vne with this stock rudder.

The reasoning behind using the larger rudders (RV-8 at first, then finally the late RV-7/RV-9 rudder) on the -6 was to help with spin recovery. You do not want to intentionally spin a -6. It is capable of spin recovery with the original small rudder, but the spin develops very quickly and will take much longer to recover with full recovery control inputs than what a "regular spamcan" trainer airplane will do. In other words, spinning a -6 will probably scare the holy crapola out of you and might make you panic (and if you don't have enough altitude, then you know what happens next). The larger vertical stabilizer/rudder of the early RV-7 (which is actually an RV-8's VS/rudder) or the later RV-7 (actually the RV-9's VS/rudder) have both been used on RV-6s and both help with spin recovery, the larger late RV-7/RV-9 rudder being the most effective..... BUT, both weigh more than the original short tail, and if you've got an O-320 with fixed pitch wood prop on an RV-6, you may have some aft-CG issues, which is not good for spin recovery either. Both of the larger VS/rudder options also have more drag, which results in a lower top speed too. Many folks think the taller tails don't look as aesthetically pleasing on the RV-6 either. It's all a series of compromises and trade-offs. Here's Van's service bulletin about spinning a -6 or -7: http://www.vansaircraft.com/pdf/sb02-6-1.pdf

As for my personal opinion, I prefer the smaller tail on my RV-6. It looks better, has the least drag, and I don't intend to intentionally spin this aircraft. It does however require a lot more right-foot pedal on takeoff and climb, and needs some left-foot pedal on descents, to center the ball, but that's what developing good "stick and rudder" habits is supposed to be all about, correct? After flying a Piper Cherokee for a decade (which has rudder pedals just so you can steer the nosewheel while taxiing) flying the RV-6 is like learning how to fly an airplane all over again :D
 
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Neal,
Thanks for the additional info.
This forum is Great!
Over here the fuel cost is around 3 USD for one liter!
So running at about 30lt+ / hour is a little spendy....
With a smaller engine like the UL power 130hp or similar the fuel cost will be greatly reduced.
As I understand from Van´s site the RV 9 is happy with 135hp although the climb performance is somewhat "moderate"
On the other hand the wing on the 6 is perfect for those gentleman aeros i like...
Choices choices.....
 
speedbird said:
...
With a smaller engine like the UL power 130hp or similar the fuel cost will be greatly reduced...
Click to expand...

It is said often but I will repeat it one more time. Fuel cost has almost nothing to do with the engine size in the recommended range for 2 seat RVs. It has almost everything to do with how fast you choose to fly.

I have a 180 HP on my RV-6 and have flown formation with a Cessna 150 with a 100 HP engine. My fuel burn was far less than his. I have also flown in group flights of RVs with engines from 150 HP to 200 HP. Once again the fuel burn difference is very close and has more to do with individual leaning techniques than engine size. Often the highest HP engine would have the lowest fuel burn.
 
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Oops... Forgot to tell you that you have a nice looking 6 over there...
Back in 93-94 when i lived in Addison (building multi engine hours and picking up my CSMEL and IFR ratings) before coming back here to validate and stuff, I used to drop down at F14 sometimes!
As far as I remember it was nice and friendly people to!
Longing to get back for the bigger freedom around flying you guys have over there.
Cheers!
 
Larry, I do agree, almost :)
When throttled back you can save a lot and some engines work well in the lower rpm settings to, actually its great to have them muscles when needed but running mostly on a very low setting will also affect the combustion, I guess with demands for at perfect leaning or full FADEC.
Also big Cubic inches demands more fuel to run. (cant remember the formula)
But I do agree fully if you want to go fast well... Then you pay more!
If I had the 6 and intentions was merely to have maximum fun the bigger engine is definitely a must!
On the other hand, maximum fuel economy, less cubic inches should work better (on the right side of the power curve / drag, and any engine running at full or near full throttle isn't the best economical approach either.
Maybe the best engine choice on a 6 is the bigger engine for best fuel economy not so sure its the same on the RV 9 though, under normal "sweet spot" rpm´s.
As I remember that wing was design to do well on less hp.
Thanks for the input!
 
For the record:

For the record:

empennage

em?pen?nage (mp-nj) n.
The tail assembly of an aircraft, including the horizontal and vertical stabilizers, elevators, and rudder.

fuselage

fu?se?lage noun \ˈfy?-sə-ˌl?zh, -zə-\

The central body portion of an aircraft designed to accommodate the crew and the passengers or cargo.

:cool:
 
The smaller engine on a taildragger RV-6 will also result in aft CG issues. Mine with an O-320 and wood prop could still use some more weight up front... even though I've got a Landoll inertia ring on the flywheel that adds about 11 pounds up there. The larger engine and/or metal or CS props on a -6 will fix the aft CG problem. ;)

As for "gentleman's aerobatics", the -6 wing sure does some beautiful rolls for a side-by-side airplane. I haven't had the courage to try a loop in it yet... the last time I looped a plane was over ten years ago, in a T-34 that had enough engine to muscle its way around the loop effortlessly... and there was a retired Navy aviator in the front seat.

We still have a good little grass-roots aviation community here at F14. No RVs are under construction at the moment, but there are more than a dozen homebuilts of various types based and flying here. We still have lots of USAF and Euro/NATO pilots hanging out here from Sheppard AFB too, and frequent airport events like pancake breakfasts, hamburger cookouts, pumpkin drops, etc, and a newly revived local EAA chapter.
 
Sounds fun!
I remember when I dropped in at Mt. Vernon Chapter 834 if I remember it right, back in 94 there was an interesting little feast too.
Maybe the future will bring one back to sample some of the delicious stuff you have in your community...
Remember, A second in the mouth, a lifetime around the waist ;-)
All the Best!
 
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Fuel and big engines

Speedbird, they are correct about things evening out between bigger and smaller engines in the fuel economy issue, a bigger engine has to do less work to get the same power. However, there is a point where it just becomes over powered and the bigger engine will cost more in fuel. 160's to 200' hp seem to be on the good curve.

Personally I would not walk away from the 6..... they will operate happily on a 150 hp engine upwards. Keep them throttled back and you can get the fuel burn quite low. 25mpg or better is achievable.

Now, my RV9 has a Wam diesel 17 litres an hour on Avtur!!
 
speedbird said:
....The whole reason for not go with the original wing is economy....
Click to expand...

One of the big reasons for the lower power required with the -9 is the longer wingspan. Assuming that all you were doing was changing airfoils and keeping the span the same, you wouldn't get all the improvement you expected. And if you used the greater wingspan of the -9, you'd need it's larger tail, too.

The -6 is a good airplane. So is the -9. But it's not worth morphing one into another; you'd be better off selling the -6 kit and buying a -9 kit instead.

Dave
 
Nike

Neal,

Get some instruction and get comfortable with your plane. Then, take it over the top. I have a 6 and it loops beautifully. You will really enjoy it. The aircraft is capable of much lower entry speeds than advertised by Vans if you are smooth. A former Naval Aviator myself.
 
Dave,
The deal on the 6 is to god to walk away from and I really do like some aeros now and then so she will stay original with the exception of maybe the rudder change for more surface...
Guess she is a god compromise between fun, and relatively decent economy after all.
And god looking too!
 
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