Allen

thanks Simon & Ray - I don't want to start a 'numbers war' we fly all manner of craft, and that's just fixed wings the common thread - enjoyment so, peace and love everyone me, I'm leaning toward light, small and slow the NZ authorities are likely adopt the (unproven) 250g limit plus old age, and my Scots ancestry (?) EDF's are new to me so, can anyone please explain Section 3.7.4 - Richard Sharman's static calcs thanks

‘150 watts per pound of model’: back in 2011, Richard commented this ‘rule of thumb’ is useful, but can’t be explained I can’t explain it either, but a pdf on (propeller) park-flyer design lists 100 W/lb as the border between ‘fun’ and ‘insane’ performance EDFs are often used on ‘fast jet’ types – there’s a clue And the thrust per Watt from a comparable set up for an edf is less than a prop So, ‘add a bit of Clarkson’ – more power! Aka add 50%, and there’s 150 W/lb

A question for Richard (or anyone who knows): I have read (most of) the posts on this thread I have also read thru Richard’s pdf ‘RS_EDF_theory_and_Practice_v5’ But I get lost at section 3.7.4 – adjustment to KS theory Especially para 5 – the Hawk example And especially - “take account of dv = ve – vi we obtain a value of vi = 7.6 m/sec How is vi obtained? This is the static case, so vi = 0. More detail please…

hello One of Richard’s scopes – in post 1 – was “check the performance of the model and EDF unit” (against theory and practical experience) Has anyone built and flown a suitable flying test bed? Maybe something like an Alphajet pod-and-boom plane, (or the Ezefan) Can hang a variety of fans on it Ditto re entry and exhaust ducts And compare actual flight with theory Because, as nice as the models shown are, they are complex Multiple inlets, curved tubes, obstructions, etc This approach might be better suited to an ‘academic organisation’ Altho the hobby is full of keen and dedicated amateurs…