On 2008-06-25, wrote:
I'm thinking of a clean glider, one that might weigh 1500 pounds and
has a glide angle of say 1 in 25.

That's not really a 'clean glider' - that's less than the performance of
an old wooden glider like a Slingsby Skylark. Modern training gliders
like the Puchacz have a glide of 30:1.

Now if I add an engine swinging an 8 foot diameter prop, maybe as a
pusher, the question is, how big an engine for cruise only?

As a point of reference, the Ventus 2ct (a 'turbo', no it's not
turbocharged, but for some reason self-sustainers are called 'turbos'
here) is a 2 seat glider which is genuinely clean (around 45:1 glide),
with an all up weight of 600kg (around 1300 lbs or so), has a 20
horsepower engine. So you're in the right order of magnitude. It doesn't
have an 8 foot prop either (it's a teeny little 5 blade prop IIRC, and
the whole engine/prop retracts just behind the cockpit).

--
From the sunny Isle of Man.
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