When MYRO has its permit inspection, it’ll also have to be re-weighed. This will be necessary even though it was only weighed in August last year because several replacement parts have been used in the repair which may affect the weight. It’ll also be complicated by the fact that I have added the second tank and want to put that mod through at the same time. The BMAA Weight and CG Report is quite complicated and has to be completed and sent in by the inspector but I want to be able to do my own calculations in parallel, as I did last time, and also get a feel for what flexibility I will have with seat weights and fuel load in the two tanks in order to stay legal (max weight no more than 390kg and centre of gravity within the prescribed min and max limits). So I’ve spent this evening creating an Excel spreadsheet that does all that for me. I’ve used it to check on the figures from last time and although I’ve made it primarily for my own use, it will in fact work for any 3-axis microlight – all that is needed is for an owner to ‘plug in’ the numbers from the relevant TADS/HADS for their aircraft into the red boxes in the spreadsheet, which is protected so no formulas etc can be changed or lost by mistake, and all the figures are updated automatically.
It’s very useful for older aircraft like the AX3 which have a low maximum weight and need to trade fuel for weight if, like me, you increase the tank capacity and need to know how much fuel you can add with any given passenger. Here’s a pic of the top of the sheet with the main boxes showing the variables already entered for an AX3 with twin tanks.
All I’ll need to do is add the new weights in each wheel box and the spreadsheet will reproduce all the calculations that the BMAA need on their report, such as with min cabin weight (55kg) and no fuel, min cabin weight and max fuel, max weight in 1 seat with nil and max fuel etc etc. At the same time the spreadsheet then compares the results of the calculations with the parameters from the HADS (max permitted weight and min/max C of G limits) and indicates whether they are ‘acceptable’ or ‘unacceptable’, telling you immediately whether you’re legal or not. There’s a ‘free’ calculation section at the end of the spreadsheet which is especially useful when you are planning a real flight with a passenger to let you calculate the amount of fuel that it is legal for you to load and here is a pic of that.
And finally, here’s a shot of the bottom of the spreadsheet with the old weight figures plugged in for me flying MYRO with a 10 stone passenger that shows I could load full fuel (both tanks full) and still be legal. It also shows the figures for a couple of the other ‘standard’ calculations, both of which have ‘unacceptable’ results
In case anyone would like to have the spreadsheet to either use or just play with, you can download it by clicking on the following link.
If you do try it out let me know how you get on.
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