RV-4 CG issues?

I've been looking into both the 4 and 6 models. Several people have mentioned that CG might be an issue in the RV-4 with a passenger. I'm just under 150lbs, but most of my passengers would fall into the 170-200lb range. With light bags, would this be a problem in a fixed pitch prop RV-4?

In my opinion, it depends.

Is that fixed pitch prop metal? You might be more comfortable with more weight in the back. If you go fixed pitch wood you'll have to lighten the load a bit more. I'm not comfortable with more than 180lbs in the back. I have a fixed pitch wood prop with a Landoll harmonic balancer. A friend has a CS prop and he can get 250lb-ers in the back no sweat. Like Smokey Ray says, just keep light girlfriends and you shouldn't have to worry.

Rv-4 Cg

I would tend to agree with Scott. I have about 400 hours in 2 RV-4s both with 180 hp C/S props. Solo the airplane is a little nose heavy. Very stable in pitch (certainly not as peppy for acro but I do very little of that). I can carry up to about 220 pounds in the rear (with reduced fuel). But not too many 220 pounders can fit. With a pax in the rear, pitch sensitivity increases noticeably but it is not that bad, just different. With my airplane, a 180 pounder in the rear puts the CG right in the middle. Personally I'd go with at least a fixed pitch metal prop.

Doug Weiler

I've got a 180hp -4 with a fixed pitch Sensenich. (BTW, the Sensenich people are GREAT! Right up there with the FBO at Raton, N.M., but that's another story)

I'll put 220 pounders in the rear pit, with no problem. I haven't noticed any pitch sensitivity, but taxiing is really different! It took a few flights to remember to leave the tailwheel on the ground a bit longer on takeoff...

Unrelated to CG really, but I carry about 5 additional knots on landing also with a load in the rear pit. The RV acts more like a Piper than a Cessna when it gets slow. It will mush rapidly rather than pitch over if you get slow, and that's confirmed by not only my experience but the 3 no power landings I've been privy to, the last one this weekend at my local airport (RV8). Having said that, it WILL stall and pitch over if she's mistreated!!! In the words of our master and hero, Richard Vangrunsven, "DON'T STALL, DON'T STALL, DON'T STALL!!!"

In the end, Smokey is right...only lithe, attractive, wealthy, (ok, I added that one) girlfriends.

Jeff
Toucan N605RV

CofG

Hi, my two cents worth. I ahve an RV-4 with O-360 and wood prop has basic CofG at 17%/950lb, with me that limits back seat to about 120kg, but I would hate to carry anyone like that! Pitch sensitvity certainly increases (I've carried 100kg pax), and tailwheel load goes up a lot. Gross weight limits me more than CofG I find. With me, my wife and full fuel leaves me ~12kg for baggage, and Cof G isn't an issue. I think the O-360 engine negates most CofG problems with the -4, but aggravates the gross weight limitation. An O-320 and wood prop would be the opposite.

Flying technique

I had a O-320 and constant speed prop (Metal Hartzell). I know I was at the fwd end of the CG range solo. I traveled several times with girlfriend and camping gear at gross and aft CG. Just be aware of the way it will handle.

I am not saying you should ever fly aft CG, but at the aft CG limit there is a large differnce in control feel when at aft CG from solo weight. One example when you land you may find just before touch down you will actually be applying slight fwd pressure just be for touch down. Other wise you may find the tail wheel will hit first. Also on take off with the tail up it will take little back pressure to lift off. In general pitch control will be very light. You may want to wheel land at a little (just a little) higher speed than your normal solo landing touch down speed. Also at altitude, trying to climb higher at lower speeds, controls are light and not as solid than at solo weight. The point is it flys way differnt at the ends of the CG range. Safe, but you need to be aware of it.

Cheers George