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need help moving CG forward on RV-6

rv-6hank

Member
I just bought a 2007 rv-6 with 0-320 150hp It has a wood prop I need to ad some wieght to the front of my plane to move the cg foward.I was told there was a heavier prop spacer,If anyone has any ideas plz let me know...
 
Welcome to VAF!!!!

Hank, welcome to VAF.

Good to have you aboard.

Can you put a constant speed prop on the engine???

That way, you would be gaining something for the extra weight.

Or, a metal prop might help.

Battery on the engine side of the firewall.

Good luck.

PS, love the bio info;)
 
How much weight do you need? These are two simple ideas. You could add a Landoll ring to the starter ring. I think it is about 12-13 lbs. or you could buy a heavier crush plate. Use the contact info below for the crush plate and prop extension.

Saber Manufacturing Inc.
3601 Nassau Ct, Granbury, TX 76049
Ph: (817) 326-6293 Fax: (817) 326-6330
E-mail: [email protected]
www.sabermfg.com
 
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The battery has already been mentioned. The nice thing about the battery move is the airplane can loose a little weight when you go to shorter cables. Where is the battery now?

If it has a lightweight starter, you can always go back to an 18 pounder.
 
You could trade your nice lightweight starter and alternator to me. I would be glad to exchange them for some heavy ones.
 
As mentioned, the heavy Prestolite starter helps a lot. On my airplane (a wood prop, 160 hp RV-6), I also installed the ELT right behind the battery and have the strobe power pack right up against the firewall.

With my airplane, CG is rarely a problem unless the airplane is low on fuel, hauling me and a heavy passenger, and loaded to the gills for air-camping at Osh or SnF.
 
Thanks for the help. I'll check on these things. If anyone knows where a used metal prop is that would be great.
 
O-320 2600 RPM prop redline

There is a 2600 RPM prop redline on the Sensenich metal prop, which can limit top speed. You would be better served to use the Landoll Balancer, a steel prop spacer and the heavy starter and alternator.

You can probably find lots of folks willing to swap a heavy starter for your lightweight one. LOTS cheaper than replacing the prop.

Do some W&B calcs. The steel prop spacer and starter are way ahead of the CG and will make a significant difference.

Larry Tompkins
N544WB -6A
W52 Battle Ground WA
 
Just get a heavier crush plate from Saber. They will have a wide variety of weights to suit your c.g. needs. Weight has a tendency to smooth out lightweight props anyway.
 
Mark Landoll has "hung up his tools." That's his quote from an email response I got from him last week when I was looking for an inertia ring. Looks like Sabre is the best bet if battery, prop, etc isn't sufficient.

Dave
RV-6 ultra slow build (11 years and counting)
Fiberglass, fill, sand...repeat ad nauseum
 
CG forward

I had a F/P senenich metal prop on my RV6. It did help the CG forward.

There are two issues with changing from your wood prop to the metal prop.

1) The heavier weight has a penalty of much slower spin-up and spin-down. This is a real negitive difference compared to a lighter wood prop, (response.)

2) The metal senenich prop is good and robust. The trade off is the issue of a factory RPM redline limit of 2600 vs the engine limit of 2700. This lowers the high speed cruise and more importantly it lenghthens the take off distance. Also, this RPM limit reduces the climb rate. Other RV's with wood props outclimbed me every time.

Due to the above two items, I would rather consider the heavier starter which will not lower performance as the prop will.

On a RV6 it is very near 15 pounds of weight at the front will equal (1) pound of weight at the tail.
 
I understand vans make a lightweight tailwheel which would achieve the same thing cofg wise as adding weight at the front, but with a (small) weight advantage rather than a penalty. Not sure if there are other significant variations between the various tail end components but this one may be helpful.
 
C/G

I understand vans make a lightweight tailwheel which would achieve the same thing cofg wise as adding weight at the front, but with a (small) weight advantage rather than a penalty. Not sure if there are other significant variations between the various tail end components but this one may be helpful.

This may be the ticket depending on what type of airports used.

(1) lb at the tail is equal to approximately (15) lbs at the nose.
 
Along the same lines as the lighter wheel, I was told recently there is a titanium stinger available (not sure who from, what $ or what weight is saved), but this would also help move the cofg forward. Also there must be some weight variation with the various forks and steering links.
 
Starter ring

I've got one of the flywheel/starter rings, not sure who made it, that I could sell if someone is interested. It came with a prop I bought, but it appears to be in very good condition. If anyone is interested I'll take a picture.
 
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Along the same lines as the lighter wheel, I was told recently there is a titanium stinger available (not sure who from, what $ or what weight is saved), but this would also help move the cofg forward. Also there must be some weight variation with the various forks and steering links.

I've been wondering about a titanium tail spring for a while. Seems like a great solution to a fairly common issue. Does a prefab spring actually exist, or does anyone have any leads on who might be able to make one? More info would be hugely appreciated...

I also need to move my CG aft on my wood propped O-320 -6. I relocated a 1.7lb strobe power pack from the tail to under the baggage floor, which was worthwhile. Still need some more, would love to do it w/o adding weight.

-jon
 
What about using the "long" RV-9 engine mount; the one they make for the O-235 installation in the RV-9?

Andrew
 
OK guys,Thanks for all the help.I went back, looked at some numbers I think Im gonna buy a metal prop for my rv6.....If anyone has a 6 with 150hp o-320 let me know what prop you have an performance..Im not the lightest person an our airport is only 2500 feet so climb out is just as important as cruize to me..
 
OK guys,Thanks for all the help.I went back, looked at some numbers I think Im gonna buy a metal prop for my rv6.....If anyone has a 6 with 150hp o-320 let me know what prop you have an performance..Im not the lightest person an our airport is only 2500 feet so climb out is just as important as cruize to me..

Your options are limited to what Van's sells in Sensenich metal props.
An 78" prop pitch is standard for the 6 with a 150 hp But if you want better climb then you can use the prop for the 6A 150 that is pitched at 77".

No worry about the 2600 rpm limit on take off or climb. You will never hit it. In cruse, it is a limit that you just don't go over. It is not a big deal. If gas was $2 a gallon, then I would want that last 100 rpm, but it's not.

Also, the heavier weight of the prop allows the motor to idle lower and allows you to make shorter landings.
 
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but do i have to get one from vans cant i just get the length an pitch an find a used one...


Yes, you can find them used. And you can get them from Sensenich and A/C Spruce.

What I should have said, you can't use a prop off of a Cessna or Piper for this. These props are made for RV's and other aircraft in that speed range.

Here are the part numbers that you will need..... http://www.vansaircraft.com/cgi-bin/catalog.cgi?ident=1333235858-376-402&action=search

You need to find a prop that has the right bolt size and also the right spacer for your application. The 77 pitch for better climb comes with either 7/16" or 3/8" bolts and 2 1/4 or 4" spacers.

A 78" pitch is standard for your RV6 with a 150 hp motor.
 
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