I go solo at the community centre, find ways to ensure that formulas match, and have an interesting time with an Arrowhawk.

## Going solo at the centre

This morning while helping Jenny to get things ready for tomorrow’s community lunch, I learn that Rachel is not going to be here at the community centre for a whole week, so I’ll be manning the place solo in the interim.

This also means that when Chris stops by to pick me up this morning to help with the food co-op, I have to tell him that I won’t be able to go with him to volunteer with him as I’m the only one here now to keep things going. It’s a bit of a shame but is how things need to be for the meantime.

## Checking matching formulas

The air performance formulas are getting a bit more difficult to test now, for I’m wanting a good way to go from one to the other without assumptions being made between them.

For example with the two formulas, both have the same result but how can I determine that the program is correctly working them out?

$C_{L,minS}=\sqrt{3\pi\cdot eAR\cdot C_{D,0}} \\C_{L,minS}=\sqrt{3\pi}\frac{\sqrt{A_D}}{c_e} \\ \text{where:} \\ C_{L,minS}\text{ is the coefficient of lift at minimum sink} \\ AR\text{ is the aspect ratio of the wing, }C_{D,0}\text{ is the parasitic drag on the aircraft} \\ A_D\text{ is the overall drag area of the aircraft, and }c_e\text{ is the effective chord of the wing}$

It can be done in this case by breaking some of the terms down in to simpler units

$AR=\frac{b^2}{S} \\S=b\cdot c \\A_D=C_{D,0}\cdot S \\c_e=\frac{c}{\sqrt{e}}$
where b is the wing span, c is the average chord of the wing, and S is the total wing area

And with those fundamentals, it is now fairly simple to ensure that both of the original formulas result in the same answer.

## D&D Evening

And lastly at tonight’s D&D session we had an enjoyable time, where when scaling a cliff we’re attacked by a large flying creature, an Arrowhawk. When the psion in our party lost her grip on the rock, the daily special ability from her boots teleported her to the nearest horizontal surface which just so happened to be at the top of the cliff, resulting in the rope connecting her to the rest of us breaking. The bird came in to grab me next, and our warlord launched himself at it and managed to cling on to its tailfeathers.

I next attack it from within its claws and get dropped, and While falling attempt to tie the end of the rope around my warhammer and hook it around the bird. Somehow I manage to roll a natural 20, and succeed with great success in hooking the warhammer between the toes of the bird, which is brought to a good landing.