G ratings for RV-4

[kleecker]

Newbie question. I have seen RV-4's being sold as "fully acro", yet I have not found anything on Van's site to indicate that the RV-4, any year, would fit the fully acro (+6, -3) category.

Unfortunately I do not have the funds for an RV-7 or RV-8; price-wise the RV-4's (completed, low hours) fit my budget, but utility rated loads will not be sufficient. I base this simply off my performance envelope / capability / comfort zone racing (AMA) motorcycles and cars in the past; slow to start, but quick to progress to driver's limits, then finally to vehicle's limits.

If this is a frequently asked Q, could someone reply with a link to the discussion?

Appreciate your time, and hoping no flames.

Mark
'79 Grumman Tiger

 

[Steve Sampson]

+6 -3

Mark, p15-21 of the builders manual says;

"The structure of the RV-4 and RV-6/6A have been designed to withstand aerobatic design loads of plus 6 Gs and minus 3 Gs at an aerobatic gross wt of 1375lb, ..."

So I hope that puts your mind at rest.
The fact that you are going directly to a -4 is an advantage. I made the mistake of a -9A first of all. I put a few comments on my blog here.

Go for it. Steve.

 

[pierre smith]

.......not fuel

Van also says that the fuel is not included in that aerobatic gross weight, so 30 gallons would add another 180 lbs, bringing the total weight to 1555Lbs.

Regards,
Pierre

 

[frankh]

what?

Is that true Pierre?

I mean are you not supposed to have an all up weight in line with Van's figures?

The 7 is listed as 1600lb gross so I assumed that gross meant gross...I.e the whole thing, airplane, passengers and fuel had to not exceed 1600lbs for the max G load.

Can you explain?

Thanks

Frank

 

[pierre smith]

I agree

Yup,
Fuel's not included. I believe that came from Ken Kreuger at Van's. Apparently the fuel you carry is not part of the aerobatic gross. In my 6A my aerobatic gross is 1375. It weighs 1065 empty and with me only at 190 I have 1255 already. 20 gallons would add 120 lbs, bringing it up to the 1375 but I was told that you don't count fuel. Apparently the fuel's location would be pressing down on the wing (similar to a Cessna 310 wingtip tanks) and not adding to the bending loads on the spar....go figure. Call Van's for a better explanation.

Regards,
Pierre

 

[garnt.piper]

G Limits

My RV-4 plans/construction manual from 1986 state +/-6g at 1375lb. When did the published limits change? And Why?

 

[Dean Pichon]

G-limits for the -4

I started my -4 in 1991. At that time, Van's literature stated +/- 6G's for the RV-4. At some point after that, I noticed +6/-3 reported. I have assumed it represents increased conservatism, and not a fundamental design/analysis change. We should probably ask someone at Van's...

 

[pierre smith]

Not really

My RV-4 plans/construction manual from 1986 state +/-6g at 1375lb. When did the published limits change? And Why?

Grant, Dean,
I don't believe the values have changed. I, and most everyone else, assumed that the 1375 aerobatic gross weight included fuel. as you'd expect. Since then, we were informed by Van's that fuel is not to be included in your aerobatic gross weight calculation, for whatever reason. What this does, is give you more leeway and in reality, a higher aerobatic gross weight. My spar is the same as yours and the -6 also has a 1375 limit.

Regards,
Pierre