Read your graphs carefully, and understand them!!!
I used to fly a Warrior from grass. I've only flown it 4-up once - myself, two other small adults, and a small child. Did the weight+balance, calculated that I'd be within MAUW.
Then did the performance calculations, and discovered that I wouldn't be able to take off - by quite a big margin!
I was ready to cancel the flight, when I looked closer at the graphs. I assume your manual is similar to mine: it has a UK CAA supliment at the back, with "revised" performance charts which you have to use in preference to the ones Piper supply? Well, the CAA graphs only cover flapless take-offs - there are no graphs for the short-field take-off, despite the fact that the technique is described in the manual!
(The solution, on the suggestion of my old instructor was as follows: Do the performance calculations on the Piper graphs. Calculate take-off distance for short-field and flapsless. Find the percentage difference between them. Then do the calculations on the CAA graphs, and apply the same percentage reduction for the short-field take-off as the Piper graphs give you. Using this method, there was about 100m to spare, once all the safety factors had been taken into account. And, sure enough, the 'plane got off with well over 100m to spare.)
FFF
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