Weight and Balance

[hman1359]

I just purchased an RV-4, and am loving it. I had a question about W&B though. The info the plane came with listed the empty weight at 1014lb, with an empty cg of 66” (datum 60” fwd of LE). First, the weight seems high for the plane. It’s an O-320 fixed pitch wood prop with VFR only instruments and a short gear. Second, it seems like no matter what I do, the CG is extremely far forward. Even with baggage or a passenger or full fuel, it’s pretty close to the forward limit. Is this normal? I asked the seller and he doesn’t know when the weights were taken. Is it a good idea to reweigh the plane? And can I do that myself?

 

[rv8ch]

I'd try to find and join a local EAA chapter and see if they have scales and someone that knows how to use them. Knowing this will be very helpful for safety, not to mention the legalities, which I can't address.

 

[lostinsuisse]

Just for comparison, my RV-4‘s empty weight is 1019 lbs and the CG is 70.76” aft of the same datum as yours.

It is also a O-320 and has a composite prop.

-jim

 

[Dan 57]

Is it a good idea to reweigh the plane? And can I do that myself?

It definitely is a good idea, and of course you can do it yourself.
The process is given in the build manual, and as by Mickey's suggestion above, try get access to validated scales either thru your local EAA chapter or maintenance outfit.

I vouch a fresh weighing will give you differing figures to the ones you have...

 

[RV7 To Go]

I have had 2 RV4's. The first was 947 BEW and 71.53" CG and the second 984 BEW and 71.76" both same datum as yours. Both had light composite props (Prince and Hertzler) with O-320 engines. I think most 4s will easily go out the back of the CG range with a passenger and baggage. We have 2 other 4s on the field both with wood props and O320s and both are in the mid 900 lb range and have the same rear CG issues with too much weight in the back. I would definitely reweigh and confirm the numbers.

 

[hman1359]

Thanks all. I'm going to do remove the vacuum pump and (broken) gyros first, and then going to reweigh. I expect I'll get substantially different numbers. Appreciate all the advice!

 

[Dugaru]

Thanks all. I'm going to do remove the vacuum pump and (broken) gyros first, and then going to reweigh. I expect I'll get substantially different numbers. Appreciate all the advice!

If you want to come visit us at W96 (not that far from you) we’ve got three postal scales in my hangar that we recently used to weigh a Cessna 120 and my RV-9A. Always happy to host another RVer!

 

[jclark]

Thanks all. I'm going to do remove the vacuum pump and (broken) gyros first, and then going to reweigh. I expect I'll get substantially different numbers. Appreciate all the advice!

If you have the opportunity, you MIGHT want to weigh it BEFORE you make changes so that you have that data to compare with what you were given. Then when you make changes, you can compare that data as a cross check to make sure that it all "makes sense".

Looks like you are located in NC. At KCUB, (Columbia, SC) a consortium of us bought some "high dollar" scales. I think that we have said that for a small donation (I forget the amount, but reasonable) someone could use them (e.g. in my hangar ... I have space).

That reminds me, I need to weigh my plane AGAIN under some different configurations.

 

[hman1359]

If you have the opportunity, you MIGHT want to weigh it BEFORE you make changes so that you have that data to compare with what you were given. Then when you make changes, you can compare that data as a cross check to make sure that it all "makes sense".

That's an excellent point. Thanks. Until I can complete my transition training with the seller, it's gonna be a bit away from me. I expect I'll have the insurance requirements completed in 2 weeks or so though, and will definitely look into going somewhere with a good setup!