Hi all,

I'm new to the forum but am hugely impressed with the SD software so far which I intend to put on an iPad 3 soon.

I'm afraid that I seem to be having a complete nightmare when trying to enter the figures into the Weight & Balance boxes and forming the polygon for my FD CTSW (472.5kgs). Everytime I plan a route, I keep seeing the red message: "The aircraft is either overloaded or outside of its acceptable centre of gravity envelope" and it's driving me nuts!!

It's a fairly common light aircraft and I wonder if anyone out there has done all the hard work for me and can post the profile figures for their CTSW on this forum?

Many thanks!

Grila

If you post all the details, I'll gladly create a profile for you, or tell you what to enter.

Hi Steve,

Thanks very much for your offer of help!

My aircraft is a Flight Design CTSW.

The MTOW is 472.5 kgs. The Max ZFW is 290.5 kgs. The Max Empty Weight is 290 kgs. The datum is the leading edge of the wing.

(If allowed, the max weight of the aircraft with full fuel (@ 93.6 kgs), 2 x 100 kgs crew and 25 kgs baggage = 608.6 kgs).

The weight is distributed as follows:

Port Wheel: 120 kgs. Position from datum: +0.570 metres (Moment: +68.4 kg.m)

Starboard Wheel: 116 kgs. Position from datum: +0.570 metres (Moment: +66.12 kg.m)

Nose Wheel: 54 kgs. Position from datum: -0.905 metres (Moment: -48.87 kg.m)

Total Moment: +85.65 kg.m

Current Empty Weight = 290 kgs

Empty CG Position: +0.294 metres

Fuel: (2 x 65 litre tanks situated in the wings but considered as one tank):

130 litres = 93.6 kgs. Position from datum: + 0.21 metres (Full Fuel Moment: +19.65 kg.m)

Seat 1:

Minimum Load: 55 kgs. Position from datum: +0.52 metres (Moment: +28.6 kg.m)

Maximum Load: 100 kgs. Position from datum: +0.52 metres (Moment: +52.0 kg.m)

Seat 2:

Maximum Load: 100 kgs. Position from datum: +0.52 metres (Moment: +52.0 kg.m)

Baggage:

Maximum Load: 25 kgs. Position from datum: +1.2 metres (Moment: +30.0 kg.m)

Forward CoG Limit: 0.257 metres

Aft CoG Limit: 0.450 metres

Current Max Forward CoG Position: 0.305 metres

Current Max Aft CoG Position: 0.426 metres

Thanks very much. If you require any other figures, please ask!

Paul

Hi Steve,

Many thanks for all that. I do appreciate it.

Just to clarify some points for you.

Forward CoG Limit: 0.257 metres. Aft CoG Limit: 0.450 metres

Current Max Forward CoG Position: 0.305 metres. Current Max Aft CoG Position: 0.426 metres

The first figures are the manufacturer's limits for the fwd and aft positions of the CoG.

The second (current) figures are where my CoG limits currently are at minimum and maximum take-off weights.

The 608.6 kgs MTOW figure is the manufacturer's design maximum take-off limit. 472.5 kgs is what my aircraft's MTOW is due to being constrained by the UK's Section S microlight requirements.

I'm sorry if I caused any confusion!!

I just entered a fictious route to check my W&B with my new polygon (which appears as a very regular oblong shape) using 35 litres fuel, 85 kgs in seat 1 and 60 kgs in seat 2 but the green arrow seems to always be a little bit outside the top edge of the polygon. Am I reading things correctly?

Regards,

Paul

Hi Steve,

Due to that confusion between the manufacturer's CoG limits and what my CoG figures were with my current minimum and maximum weights, I have just changed my polygon fugures to use the manufacturer's CoG limits which now read:

0.257,290, 0.257,472.5, 0.450,472.5, 0.450,290

instead of

0.305,290, 0.305,472.5, 0.426,472.5, 0.426,290

However, with my ficticious route, I still get my green arrow outside the top of the box!!

Regards,

Paul

Hi Steve,

Just a thought but does the fact that the 'plane wouldn't actually fly without the minimum weight of 55 kgs in seat 1 make any difference? Should that be another set of figures added to the polygon string?

Regards,

Paul

Technically yes, but if there wasn't 55kg in at least one of the seats, who would be flying it?

Hi Steve,

Yes, the arrow is at the top of the box and there is no warning being generated!

Many thanks again.

Paul