Saturday, February 27, 2010

Tsunami Warning!

This is not a drill.

After the earthquake in Chile, there is now a tsunami warning.

A little useless at this late hour, but might as well try to spread the word.

Starcraft II

looks like my mothing skills and sleep patterns may suffer in a few months.

Tuesday, February 16, 2010


new poll to address teh elephant in teh room...

Sunday, February 14, 2010

Walk of Shame

It was me 2 weeks ago and Markla this week. This time however, a bit more damage occurred after foiling into the shallows. The strut has cracked right down the leading edge and its torsional stiffness has pretty much gone, making it unmanageable in flight. Plans are afoot for repairing them.

Markla alleges he was in the channel at the time however the pure pwnage of the foil tells a different story. The approx location of teh catastrophe is below.

It was a long walk back to deep water.

Wednesday, February 10, 2010

follow up

follow up to this...

approx camera location

house boats started here

house boats ended here

Tuesday, February 9, 2010

good time to be in repair/refit

this is what 400mm rain in less than 24hrs will do...

My local stomping ground.
Wind looks good for the weekend.
It will be interesting to see how much rubbich is in teh sea.

Wednesday, February 3, 2010

lifting line theory

for a while i have been trying to understand the lifting line theory. this has many benefits over the basic aspect ratio corrections for the calculation of CL and CDi including:
  • Non-elliptical planforms
  • Twisted sections (AoA varies along span)
  • Section changes along span
  • Wing tips (probably - see below)
it took me a while to work it all out because i didn't want to pay for a textbook and most of the internet references i found would either:
Yesterday I had an epiphany and remembered what a Fourier series was and the pieces fell into place and allowed me finally understand what was going on. I won't repeat the procedure here but I will give 3 useful links for people who do want to attempt it themselves.

Best description of method

Example to compare your results to
Simple Matlab code

A few notes on solving Fourier terms:
  • In the matlab code the line 'a=b\rhs' is matrix maths and means [An] = [b]^-1 . [RHS]
  • Look up MMULT and MINVERSE in Excel help, makes solving linear equations sooo easy and makes anyone who has coded row reduction methods in excel feel stupid.
I can supply my spreadsheet by email if anyone is interested.

Note on wingtips analysis:

I am not sure whether this is valid or not yet. Probably valid enough for anyone satisfied with a Lifting-Line theory result.
  1. Design a wing with wingtips
  2. Fold these wingtips down so they are in plane with the wing, adding to its span
  3. Twist the wingtips so that they produce zero lift, independent of the wings AoA