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Weight sanity check

Scott Will

Scott Will

Well Known Member
Got 'er weighed today! The results pleased me but I wanted to get a reality check just to make sure it seems right. Took 4 readings and averaged them out. Here's what I got:

NLG - 278
LM - 373
RM - 369
TOTAL - 1020 lb @ 79.0"

Does that all make sense for an unpainted state, no wheel pants? Equipment is IO-360, Catto 3 blade prop w/ 22 lb prop hub, Oregon seats (mine's extra thick for maximum visibility).

How much do the wheel pants and primer/paint add? I'm guessing around 40 lb... so I guess that puts me around 1060. Not too shabby, eh?

What's interesting is that my left side is 4 lb heavier than the right. I guess it's because of my thicker seat cushion on the pilot side as well as my two display screens and instruments. The autopilot servo is on the right side... would have thought that would even things out. Can't wait to get it completely finished and get the final OEW.
 
I checked your math and got the same CG, 79.01

Full Fuel, 340 lbs worth of pilot and passenger, 100 lbs of baggage, CG in limits, 85.59 inches

Zero fuel and same conditions, still in balance (just barely), CG 86.58 inches.

Looks like you have done good.
 
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Thanks! Guess I was more concerned with empty weight. Wondered if that seems within reason for similar planes (7A, unpainted, no fairings, no wheel pants, 180hp, fixed pitch w/ heavy prop hub, oregon seats).
 
My XP-IO-360 with Catto 3 blade, classic aero leather seats came in at 1034 without paint, fairings or wheel pants.
NG=238
LM=406
RM=390
CG=81, a bit to aft
empty weight=1034
Left side a little heavier due to panel avionics.
Nose gear is much lighter & is probably due to my ryton forward sump.
I could use a bit of balast up front.

I'm almost complete with my wheel pants and will weigh them and report in the next few days.
 
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Sounds pretty good. I have a Hartzell (57 lbs) on an 0-360 A1A, fully painted, wheel pants, interior with side panels and carpet, full steam gage panel with 26 CBs. I came in at 1117.

Roberta
 
Scott,
What pitch did you get from Catto?

Mine is 66x78 and was having problems getting rpms.
I thought I might be overpitched.

The concensus was to break in the engine & clean up the airframe.
I was originally getting 2380 @ wot, but around 12 hours I was starting to climb up into the high 2400 / low 2500. I should be back flying in about a week and will see if the rpms increase.
 
It's time for you everyone to feel good

I thought my RV-6A (small rudder) was going to be light because the airframe was basicly the same as everyone elses ... well except for the extra 1.5 feet of wing span adding tip tanks, the Hartzell C/S prop and the LASAR ignition control box. However, it ended up weighing 1201 lbs, my structure must be some sort of aluminum/lead composition. Still, it's pretty fast.

Bob Axsom
 
I reckon my 4 is about 600 lbs with the wheel pants. Currently, power is provided by me pushing the thing around my shop. :D
 
Dan L - my prop is 66x76. haven't brought it up to full rpm yet but it definitely is pitched less than yours. Craig said it was for max cruise and I should see 2300-2350 on the ground. Will report in a few days.

Dan C - thanks! I used your site to run a lot of W&B numbers before I purchased my prop & hub.

Overall it sounds like my weight is reasonable and on the lighter side. Would be interesting to get a feel from other RV'ers what the paint adds and where.

Going for transition training with Pierre next weekend!!
 
Prop

Dan,
I have an 0-360 swinging a three bladed Catto and Craig pitched it to 76" with a 66" diameter. It'll only pull 2200 Static and around 2350 on a 135 MPH climb, two aboard.

Yesterday I had a transition guy aboard who might go 165lbs and I showed him a quick 185MPH and 2550 in the pattern if you don't use less Revs, like 2200 which gives me 160 MPH or so. At 7500' it will not exceed 2700 RPM as Craig said it would but that's also 202 MPH, two aboard. I think you're overpitched a bit, IMHO,
Regards,
 
Man... 1020 lb still seems awful light especially when looking at the other RVs in Dan's excellent database. Wonder if my QB has extra lightening holes hidden? :confused:

The EAA chapter scales (which I hear read pretty heavy) were not around. So I went to Sears and got some electronic ones that go up to 380 lb... kinda taking the chance that the mains would be under that. Wonder how accurate they are on the far end of the scale (no pun intended). On their website they showed a model that goes up to 520 lb but I couldn't find it locally.
 
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the final answer

Well my intuition was right!! Ran into an RV-8 guy (thanks Vic!) who had a set of scales made for planes. The kind with the arm/multiplier. The real numbers are:

NLG - 282
LM - 395
RM - 390
TOTAL - 1067 @ 79.5"

Previously I just set the mains on the bathroom scales... this doesn't take into account the sideloads.

Vic and I measured the geometry of the lever arms... the factor was not equal to exactly two! The distance was not half of the entire unit's length. So we did the proper adjustments and got the numbers above. This affected the final answer by about 14 lbs.

RV Community is great... love the help!
 
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