RV-9A's overload on nose gear?

I thought that would get your attention!

I just weighed my plane and sent in the paperwork to get my permit to fly.

I am now updating my POH with the data I gathered so far. I know that the nose wheel loading is an important issue, so I wanted to incorporate it in my weight & balance calculations. Call me stupid, but I can't figure out how the max. loading of the nosewheel can only be 325 lbs. (as per Van's chart on their Website). When I calculate the nose wheel loading with only 8 Gal. of fuel and myself as a pilot (165 lbs), the nose wheel loading is already over the 325 lbs. ??? I must be doing something wrong here but I don't know what.

Why is the nose wheel loading of the 9A, 325 lbs while for the other models it is 375 lbs? Can anybody shine a light on this?

Empty weights are:
NG: 277 lbs @ 33,98"
LM: 443 lbs @ 91,65"
RM: 445 lbs @ 91,65"

Thanks in advance. Regards, Tonny.

looks fine tony

Hi Tony - I ran your numbers, and loaded like you describe, your total weight should be 1378# and the CG should be 79.6"

Looking at the chart in the Vans manual - it looks like you have about 300# on your nosewheel at that loading.

When your plane is empty (no fuel, passengers, baggage) I think your weight is 1165 and your CG is 77.9 - so the chart "says" your NW weight is about 275 - which is cool cause that matches what you measured.

For fun I did a couple of other cases:

1) Tony and Full Fuel - 1546#, 79.3 inches, ~340# on nosewheel
2) Tony, another Tony, and Full Fuel - 1732#, 80.7, ~330# on NW
3) Tony, 100# of baggage, and full fuel - 1646#, 18.9", 270# on NW

I did this quick, so no warranty on any of this (but I'm saving the spreadhseet!)

Does anyone know how the Vans charts were derived? I'd love to avoid them and have the spreadsheet calculate the NW weight. As a guess, I made my spreadsheet assume that the NW weight is proportional to how close the CG is relative to the nose gear - based on the difference between the nose and main gear moments. It seems "close" to Vans graph..

Tony - if you don't mind, do you have a CS prop or anything else "heavy" forward? After seeing these numbers, I'm wondering where my 9A will come in at. Also I noticed the ARM data for your gear don't match what is in the manual (only off a little) - did you measure your gear?

Nothing heavy up front!

Dave,

I have a Whirlwind 200 RV CS propeller (only 37 lbs), Odyssey battery, carpets and full leather trim. Glass panel, small back-up alternator on the Vacuum pad. The strobe power supply, ELT and AP servo are behind the baggage bulkhead. Primered inside/outside prior to riviting. So there is nothing out of the ordinary and the empty CG is pretty standard, if not towards the rear.

The gear was measured. I will double check it though.

I calculated that I could never get the plane out of CG, whether I would be flying allone with full fuel or I would carry a heavy passenger, max luggage and minimum fuel and minimum oil.

What you calculated is exactly what I thought, I would have to carry 100 lbs of luggage at all times to keep the load on the nose gear acceptable!?? Very strange!

A bunch of reading here.
http://www.vansairforce.com/community/showthread.php?t=23383

NW = (total weight)*(91.13 - CG)/(91.13-33.69) - using your data

Tony + full fuel:
total weight = 1165 + 165 + 6 * 36 = 1546
CG = 79.35
NW = 317.13

Tony * 2 + full fuel:
total weight = 1165 + 165 * 2 + 6 * 36 = 1711
CG = 80.63
NW = 312.63

Tony * 2 + full fuel + 75# baggage
total weight = 1711 + 75 = 1786
CG = 82.37
NW = 272.32

Since pilot, passenger (arm 92.7) and baggage (arm 122) are aft CG (77.95 - 84.84) and fuel (arm 76.75) is fore CG. To lightening nose weight you put less fuel and carry heavy people and baggages.

I have two batteries on the firewall and my empty (no fuel neither oil) nose weight is 290. With oil nose weight is 298. I don't see how I can go beyond the 325 NW limit. Only if I have full fuel, nothing in the baggage compartment and let a less than 150# pilot fly it.

Have you double checked your scales?
Vans site says the average weight for a RV-9a is:
Empty Weight 1015 - 1057 lbs
Your weight is over 100 lbs more. Wondering why based on your equipment list?

A full leather interior can easily add over 50 lbs.

weight

I was going to comment on the weight Tony was indicating. 1167# sounds a little heavy. I have the 50# (actually 52#) interior Mel is referring to and my all up empty weight is at 1085#.

I would be a little suspect of such a heavy airplane. Any thoughts on verifying that weight Tony?

FWIW, my 9A weighs 1147. I do have the IO-360 in it (adds a few more pounds than the 320), and a few minor (weight-wise) modifications. Nosewheel weight (empty) is 275 probably because my battery is in the tail. I've also calculated that it is virtually impossible to get out of CG unless highly overloaded.

greg

I modified my W&B spreadsheet

to calculate the nosewheel weight automatically. If anyone is interested, drop me a line. Or maybe there's a place to post it here?

Leaving OSH today.

Here is my version of the RV9A weight and balance spread sheet. In Section 4 you will find a nose wheel weight table as presented in Van's nose gear service letter (http://www.vansaircraft.com/pdf/Nose_gear_service_letter.pdf).


http://3limafoxtrot.com/doc/rv9aWB.xls

or http://3limafoxtrot.com/technicalinformation.htm#wb

Lots of extra's !

OK, I was shocked at first, when I saw the empty weight, because I did everything possible to save weight. Drilled every lightening hole, rounded off each and every little corner, etc.

I checked the weight with different scales, it came out the same. Below is a list that gives an idea of some extra?s that not everybody will have, but all together they add quite a bit of weight.

- Primered, inside and out, prior to riveting: 10 lb?
- Aux alternator: 2,0 lb
- Aux Battery, 4 Ah: 2,0 lb
- Aux wiring, fuses, switches, shunt, etc: 1,5 lb
- CO-guardian 0,3 lb
- Fuel Guardian (both tanks) 0,5 lb
- Fuel timer 0,3 lb
- Pull-out tray in Instrument panel 1,2 lb
- Full CAD leather interior and carpets 30 lb?
- Leather instrument panel trim 1,2 lb
- Defog fans 0,4 lb
- Sicaflex glued canopy 1,5 lb
- Fire extinguisher 2,5 lb
- 2 servo Autopilot 5,0 lb?
- Parking brake 0,5 lb
- Flexible brake hoses (gear legs) 0,4 lb
- Vettermann mufflers 4,0 lb?
- Fuel injection, booster pump and filter 3,0 lb?
- Double stack Andair fuel valve 0,5 lb
- Return lines to the tanks 1,5 lb
- Long range tanks (54 Gal) 5,5 lb
- Leading edge landing lights (2) 4,0 lb?
- Wig-wag 0,2 lb
- Swing-out fuse panel 1,0 lb
- ELT with wiring and antenna 3,0 lb
- Flap position switch 0,5 lb
- Trim speed switch and flap switch 0,3 lb
- Front gear leg stiffener and ?nut-protector? 1,0 lb
- ?Tip up slider? 0,1 lb
- Canopy lock 0,1 lb
- Arm-rest ?stiffeners? (angles) 0,3 lb
- Enunciator panel 0,3 lb
- Covered tail openings (all) 1,0 lb
- Tie-down rings installed (small) 0,2 lb
- Screwed wing tips 0,2 lb

The list is longer than this, but I guess most people will have back-up airspeed and altitude instruments, Amp shunt, CHT, EGT and OAT probes, remote compass, etc. Also the plane was painted with base coat and clear coat.

After going through this list and comparing it with a local RV9-A , I came to the conclusion that the weight is correct.

I can?t get the plane out of CG unless I put way more weight in the baggage area than allowed.
Still, this nose gear thing is bugging me.

Regards, Tonny.

rvator51 said:

Have you double checked your scales?
Vans site says the average weight for a RV-9a is:
Empty Weight 1015 - 1057 lbs
Your weight is over 100 lbs more. Wondering why based on your equipment list?

Click to expand...

Because he has a lot of "options".

BTW, I have a copy of the database Dan had up on his web site. It lists 21 -9A's, and the average weight is 1085 pounds. The heaviest was 1213 and the lightest was 1017. The light one had an O-320 w/ aluminum FP prop. The heavy one had an Eggenfellner Subaru engine up front, a 72" Quinti 3-blade Composite CS prop, and five pounds a ballast in the tail.

Keep it light, is the best advice Van's gave me while building.

As for the O-360 comment, I suspect that my -9 will come in close to 1050 after the engine swap and with a Classic Aero leather interior panels (8 lbs for both sides.).

N941WR said:

As for the O-360 comment, I suspect that my -9 will come in close to 1050 after the engine swap and with a Classic Aero leather interior panels (8 lbs for both sides.).

Click to expand...

A few gallons of "paint", aft of the spar will probably offset the weight of that extra big engine....

L.Adamson --- RV6A (heavy.. but fast)