How can I carry a back seat passenger

[vfrazier]

In my O-320, wood prop RV-4, I only carried passengers of 200# or less. And once you're familiar with the plane, you can tell if they lied about their weight!

I cured my problem by building a Rocket. No rear seat weight issues with that plane!

[designerX]

Originally Posted by marv1121

calculating the CG but that will not fix the problem.

Well it's a good start to know whether the aft control surfaces have too much paint and filler added or if there's 5 lbs of mud dauber nests in the horizontal stabilizer.

If you're happy with your propeller performance I encourage you to keep it and use one of the other methods mentioned above to add weight up front.

[marv1121]

Many thanks to all of you, this is some good info and just part of my learning curve on the RV-4. I think I am going to go with a heavy weight, old style starter and possibly a landoll ring and maybe a heavier prop crush plate. I really would like a metal prop but cost wise I am not able to do that right now.
Still looking for that easy way to add weight to the nose when I have a passenger then remove the weight and fly solo. It may be impossible but homebuilders come up with some pretty smart ideas.

[patterson]

Hi Marv,
When I went with a wood prop on my O-320 RV-4 I added the 11 pound Landoll Balancer on the nose. It made a huge difference in my ability to carry a larger rear seat passenger within CofG limits, and makes for an extremely smooth engine/prop combo too. You must remember though, whenever you carry someone in the back seat of a -4, any weight at all in the baggage compartment will compound your rear CG problems. I can easily get 30- 40+ pounds in the baggage area, but if I do, I fly solo or with a 110# girl... no Bubba's.

Ron
N8ZD

[Kyle Boatright]

Originally Posted by marv1121

Many thanks to all of you, this is some good info and just part of my learning curve on the RV-4. I think I am going to go with a heavy weight, old style starter and possibly a landoll ring and maybe a heavier prop crush plate. I really would like a metal prop but cost wise I am not able to do that right now.
Still looking for that easy way to add weight to the nose when I have a passenger then remove the weight and fly solo. It may be impossible but homebuilders come up with some pretty smart ideas.

Start with the steel ring or Landoll balancer. Then the crush plate. The old Prestolite starters really are problematic, which is why you find so many sitting on shelves in the dusty corners of hangars and shops at airports. You'll be happier keeping your modern starter.

Also, on my O-320, there is a machined pad on the underside of the engine, on the right side. It accepts 3 bolts. I've often considered bolting a chunk of lead or steel to that pad for ballast. I think most 4 cylinder Lycomings have that pad.

[marv1121]

Mike, I would appreciate that spreadsheet to make my wt and balance calculations easier. I cannot seem to figure out how to send a private message or an email to you. Here is my email.
marvin@buckeye-access.com

[Vac]

E-mail sent.

Cheers,

Vac

[SportAvServ]

Just food for thought, sense your not a builder it might be a bit of a task for you but, when I changed my .016 elevator skins to .020 the plane got a lot more stable in pitch. I had an IO-320 and a C/S prop, had to move the battery to the baggage area to git into the CG. FYI

RT

[Mike S]

Originally Posted by marv1121

Here is the deal. I have only had my RV-4 for a couple of months now. I carried a friend of mine who weighs 190 lbs in the back seat and it was scary. The pitch forces were so light that it took total concentration to keep from bobbing up and down. That tells me that my CG was way too far to the rear.

First off, you need to know what the C/G is like has been suggested already. There may be an issue with it or there may not, no way to tell until the scales come out.

Second, you state you have only had the plane for a couple months--------RV's are known for light control stick forces, so I wonder if you are just needing more time to get used to things before making a lot of changes. This is of course assuming the C/G turns out to be where it belongs. What did you fly before getting the RV?

Have you considered having someone who is a long time -4 pilot take the plane up for a second opinion???

Good luck, let us know what the end result is.

[Flameout]

I know that you are not able to purchase a metal prop just yet, so im not trying to pile on (i do also recommend the metal prop)..but i thought i'd submit my experience with my -4...

Its an early plans model from the 80's, completed in 89. O-320, wood prop, lightweight starter and alternator. The airplane performed well but was tail heavy with a passenger. Even when flown solo, it would easily run out of nose-down trim on long high speed descent from high altitude.

I changed the prop to the metal sensenich (this also includes a heavy 4" extension with long bolts, instead of the lighter "spool" shaped extension). This added 19 pounds total and the empty cg moved forward 1.34" which is a LOT! The light pitch problems with a passenger was fixed but still had limited trim authority.

Long story, but i experimented with adjusting the travel of the tab, and then added some fixed tabs on the right elevator trailing edge. I determined that the airplane just needed more trim authority. Increasing the tab deflection had limited results, even diminishing return as the deflection went past about 30-40 deg... The fixed tab on the other elevator worked great, even added some pitch stability and reduced the workload on the adjustable tab making it more effective.

I am guessing that Van designed the plane around a stock engine with the old style starter and generator, and a 900 lb empty weight. Most of our planes are lighter up front and heavier in the back (for multiple reasons!) .

At an annual i took the whole tail off to clean, inspect, lubricate, and replace a few hinges that had seized. I made a change to the aft turtle deck to make it more similar to a design change that Van did after mine was built. This involved removing the aft 4" or so of the turtle deck to allow better access to the horiz spar attach points. Then I added about 1/4 to 3/8" shim under the horiz spar to increase the incedence angle and reduce the aerodynamic downforce on the tail.
It was a lot of work, including modifying the tail fairing,,, but well worth it!

This worked very well! Much better trim authority and probably less trim drag , though i didnt notice any speed increase.

Marc