Went last October for the second time. An essential Museum visit IMHO; the worlds only airworthy Cierva C-30 (a new build which flew a few times) the earliest surviving He111, Franco's Dragon Rapide, (Olly Air Services) Dornier Do-24, loads of ex-German W.W.II era types, plus a great range of thirties a/c.
It has a hall of Spanish Civil war aircraft, a row of which are in Nationalist colours on one side and Republican on the other - a unique display as far as I know!
Bob Ogden's Museums of the World is an essential starting point. The Museum is now on the Metro (Quatros Vientos station IIRC) so it's easy to get to.
A rather ropey and out of date website is at:
http://www.aire.org/museo/ - it's missing the new Metro line, and you don't need your passport anymore (though you'd be wise to have it) The bookshop has some great Spanish language books, pins and stuff, but won't take cards, so take plenty of Euros...
The Website tells you:
HORARIO:
Diariamente de 10.00 a 14.00 horas, excepto lunes. Cerrado el 1 de enero, Jueves y Viernes Santos, 10 de diciembre (Patrona de Aviación) y 25 de diciembre.
(NB - I was chucked out at 1pm by a keen guard with a gun when I first went in 2000, so allow loads of time.)
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PRECIO DE VISITA:
0.60 Euros. Están exentos de pago: el personal perteneciente a las Fuerzas Armadas y al Ministerio de Defensa, los estudiantes matriculados en Centros de enseñanza oficial, los menores de 10 años acompañados, los mayores de 65 y las visitas colectivas. MIERCOLES: día de los museos, gratis.
On the other side of the airfield is the Infante de Orleans museum
http://www.fio.es/ (or
http://www.fio.es/actividades/actividades.htm#) - with a rather whizzy state of the art website. Imaging a Spanish version of the Shuttleworth Collection, and you get the idea. The only other flying Miles Falcon 6, B.A. Swallow, and a dozen other rare and wonderful aircraft; including a certain Bucker Jungmeister owned and flown by the late great Jose Aresti. And they fly, the first weekend in each month, from Feb onwards - see 'Exhabiciones' (ish) for dates
I got from the Spanish Air Force Museum to the FiO by hailing a Taxi by the bus stop; you can't walk from one to the other, and the bus would take you into central Madrid and out again!
Speaking Spanish helps (which I don't - but proves it's possible!)
Hope this helps.