flyrotary@lancaironline.net Mailing List Archive

Thanks Brian. I was pissed when my RV-4 weighed 1027 but I feel a little better now. Smile emoticon

Are you running 2 batteries? I am - probably an additional 20 pounds total there. Batteries are in the baggage compartment for CG reasons which requires extra battery cable length - another few pounds. Temperfoam seat cushions front and rear, maybe an extra 4 pounds. I went a little larger on radiator size than some do which means I'm carrying around extra water. Anyway, amazing how it all adds up.

When the Red Bull racers were here I was talking to the crew chief for pilot Nigel Lamb. He told me they took almost 100 pounds off the airplane during the off season. You wouldn’t believe the extremes they go to. Making control cables to exact lengths to eliminate turnbuckles, hollow bolt shanks, lithium batteries in place of RG batteries, etc....

For gross weight I set mine high enough that I could take an "FAA standard" person and 20 pounds of baggage with full tanks.

Mike Wills

From: Bktrub@aol.com

Sent: Tuesday, March 16, 2010 4:20 PM

To: Rotary motors in aircraft

Subject: [FlyRotary] weighty subject

Today was the day of judgement, the measure of my building prowness- no, not the first flight, but the weight and balance. My plane weighs 1091 lbs, weighed as it should be- no usable fuel, full oil and coolant. I for one would go with the aluminum housings if they cost me up to $1500 more than the cast iron ones. If they saved 70 lbs total, that would be around $21 for each pound saved, to get my plane down to a more svelte 1021 lbs. I'm sure I could probably get another 15 lbs off if I did some weight reduction on my Shertz beam front mount, along with other things. I also went a bit heavy on my engine mount- 1" dia x .049 thick tubes on some of the mount. I at least have confidence that my mount should hold up. The CGs all work out OK- design range is between 68.7 -77.7 inches aft of datum. Here is how it works out:

Vans states that most RV-4s come in around 950 lbs. Gross recommended is 1500 lbs.

Mine:

Empty 66.2, wt.1021 lbs

with 180 lb pilot, but no fuel-68.51, just a bit out of CG by .2 inches, total wt. 1271

with 180 lb pilot and full fuel 68.8, total wt. 1465-

with 35 lbs baggage- cg-70.38 total 1500

If I want to take a passenger with full fuel and baggage, they'd better not weigh a thing, or I'll be flying over gross recommended weight.

Brian Trubee