All,
Please refer to the following link to see a video of the Silent moter-glider
with jet engine's attached. It is absolutely amazing watching a sailplane
doing a low pass with jet engines screaming, AND self-launching.
http://www.alisport.com/pag_ing/news.htm

Yes, the Jet's on the Silent ARE retractable.

For those of you who saw the pictures of the Ventus 2 moter-glider with Jet
engines attached, there is no way that thing self-launched. It does not count
unless it can self-launch! Here are the general numbers for those of you who
would like to do the math. The engines produce 34 pounds of thrust each, and
with a flying weight of about 1000 pounds, initial takeoff acceleration would
be a blistering 0.06 G's (About 1 knot a second). You would need a REALLY long
runway (See Edwards AFB) at sea level in order to get the thing in the air, IF
they could even produce enough thrust to beat the breaking point to start the
roll (Doubtful).
-Mitch Hudson