The Regional Technical Officer who oversees the re-registration of my Fournier VH-TKD (formerly N7720) wants me to weigh the wing by itself and compare against factory specs. Dunno why...maybe he is just curious...

Anyhow, to keep the man happy, does anyone out there have the factory specified weight for the wing of the RF4D?

BR

Tim

Tell him to..........

There are no wing weight specs in the manual.

What on earth would he want that for?

All you need is the total aeroplane weight (empty).

We weighed both of ours with no fuel, taking the mainwheel weight and tailwheel weight in the stable, tail-down attitude (to get total weight) then weighed just the tailwheel with the aeroplane in the level attitude and subtracted that from the total for the mainwheel weight. That way you don't have to have your aeroplane balanced precariously on one wheel with the tail high in the air and a good chance of damage.

Figures for VH-HDO
1) Aircraft empty but prepared for service with oil, battery and full fuel system, but no fuel in tank: Weights Mainwheel 259.8 kg, moment = 17,666.4 kg mm. Tailwheel 25.6 kg, moment = 104960 kg mm. Total 285.4 kg (Manual quotes ‘about 270 kg’ in one place, 275 kg, elsewhere, and the original French manual quotes a maximum empty weight limit of 280 kg.), moment = 122,626.4 kg mm, C of G = 429.66 mm (30.69%) aft of datum (manual quotes empty C of G at 279 kg as 310 - 441 mm aft, or 22.1% to 31.5% MAC).

2) As before (no fuel), but with a normally dressed pilot aboard: Weights Mainwheel 328.8 kg moment = 22,358.4 kg mm. Tailwheel 36.7 kg, moment = 150,470 kg mm. Total 365.5 kg, moment = 172,828. C of G = 472.85 (33.8%) aft of datum (limits are 300 to 490 mm, 21.5% to 35%).

3) Aircraft prepared for service with oil, battery and full fuel system, including full fuel tank: Weights Mainwheel 288.4 kg moment = 19,611.2 kg mm. Tailwheel 23.3 kg, moment = 95,530 kg mm. Total 311.7 kg, moment = 115,141.2 kg mm, C of G = 369.4 mm aft of datum (26.4% MAC).

4) Aircraft prepared for service with oil, battery and full fuel system, including full fuel tank, and with normally dressed pilot aboard: Weights Mainwheel 355.9 kg moment = 24201.2 kg mm. Tailwheel 34.0 kg, moment = 139,400 kg mm. Total 389.9 kg (Manual MTOW is 390 kg), moment = 163,601.2 kg mm,
C of G = 419.6 mm (29.97%) aft of datum (limits are 300 to 490 mm, 21.5% to 35%).

So, Empty Weight is Total 285.4 kg
Weight of fuel = 26.3 kg = 37 lit (manual quotes 38 lit), Arm of Fuel = -284.6 mm
And, weight of pilot = 80.1 kg (correct within 1 kg), Arm of pilot = 905.9 mm

5) By calculation, aircraft at aerobatic weight, with pilot and 15 litres of fuel, weight should be 376.2 kg (max aerobatic weight is 370 kg) and the C of G is at 387.9 mm AOD (27.7% MAC) (limits are still 300 to 490 mm).

So, the aircraft’s weight is at least 6.5 kg too great, but its C of G is close to the middle of its range.

Good luck.

Yours, Bob

Weighing Fournier RF4D G-AWGN on 10th May 2008

Scales: Staffordshire Gliding Club Scales, calibrated on site with 50lb weight.
Aircraft C of G datum is leading edge of wing at root chord (1400mm).
Mainwheel arm was measured as 68 mm aft of datum.
Tailwheel arm was measured as 4100 mm aft of datum
Arm of Fuel = -284.6 mm Weight of full fuel = 26.3 kg = 37 lit
Arm of Pilot = 905.9 mm Current Pilot Weight = 81kg
Arm of Baggage = 135.7mm

Limitations: Flying Manual MTOW is 390 kg.
Max Baggage 20 kg
C o G limits Empty:
At 259 kg 310 to 437 aft of datum
At 270 kg 310 to 439 aod
At 279 kg 310 to 441 aod

C o G Limits In Flight:
Foremost C of G 300mm (11.8 in) aft of datum (21.5% MAC)
Aftmost C of G 490 mm (19.3 in) aft of datum (35% MAC)

Weighing:
Mainwheel weight (tail down) 612 lb = 277.6 kg.
Tailwheel Weight (tail down) 60 lb = 27.2 kg.
Thus Total weight = 304.8 kg
Plus pilot weight of 81 kg = 385.8 (within 390 kg limit)

Tailwheel Weight (aircraft level) 46 lb = 20.9 kg. so moment = 85690
Thus mainwheel weight (aircraft level) = 283.9 kg. so moment = 19305.2
Plus pilot weight 81 kg, moment = 73377.9
Total moment = 178373.1 / 385.8 = 462.3 mm
Thus fully laden C of G 462.3 aod (within limits)

Minus fuel moment 7484.98 = 170888.12 / 359.5 = 475.35 aod (within limits)
Thus fully laden CoG with pilot but no fuel is within limits.

Those are all wheel-down, of course. Wheel up moves the C of G forwards, but I can't find anywhere by how much, and I'm not balancing my aeroplane on trestles on the scales for anyone, so those numbers will have to do.

Both aeroplanes spin and recover and aerobat predictably, so C of G ain't a practical problem.

good luck.

Yours, Bob

Thanks heaps for the reply. I think my RTO was simply curious. I am sure he knows the wing weight has nothing to do with w&b. Anyways, my wing comes in at 93.3 kg, bit less than a Kookaburra.

Wing is back on VH-TKD, she starts looking like an aeroplane again. Next weekend I will see to that dreadful, dreadful control casting...will keep you posted.

BR

Tim

I know Bob knows this, but to be precise, there is no aerobatic weight in RF4D. The limit on 370 kg only permits more manouvers (immelmanns, rolls).

-A-

[Edit by andy1 on Monday, June 2, 2008 @ 06:00 AM]

--------------------

I did the my condition inspection yesterday and also did weight and balance. It weighted more than I hoped. We weighted it in level flight attitude. No fuel.

Equipment added over std RF4
clock
cht/egt
Becker com
Becker transponder
encoder
17amp Battery
oil cooler
ELT
ele. Turn & Bank
g meter/timer (GT 50)

664 lbs. (301.2 kg)
13.09 arm
8688.92 moment

Don't worry, both of mine are heavier than yours, and I've done all I can to keep down the weight.

Yours, Bob

cheers

Eugenio

[Edit by Sam M. on Saturday, July 5, 2008 @ 00:30 AM]