Date: Wed, 2 Dec 92 05:05:47 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V15 #485 To: Space Digest Readers Precedence: bulk Space Digest Wed, 2 Dec 92 Volume 15 : Issue 485 Today's Topics: Shuttle replacement Welcome to the Space Digest!! Please send your messages to "space@isu.isunet.edu", and (un)subscription requests of the form "Subscribe Space " to one of these addresses: listserv@uga (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle (THENET), or space-REQUEST@isu.isunet.edu (Internet). ---------------------------------------------------------------------- Date: Wed, 2 Dec 1992 04:30:41 GMT From: Bruce Dunn Subject: Shuttle replacement Newsgroups: sci.space Robert J Woodhead writes: > Autorotation not only works very well, but demonstrating the ability > to make an autorotation landing is a pre-requisite for a helicopter > pilot certificate. > > There is a very large amount of energy in a spinning heli blade, and > the principle of autorotation is to maintain that energy while using > the drag of the blades to maintain a steady (albeit high) rate of > descent until just before landing, when the rotational energy is > used to decelerate the heli. > It would be very interesting for this general line of argument to compare the descent rate of a helicopter in the high rate part of an unpowered descent with the descent rate of an aerobraked DC-1. Both vehicles are falling at a substantial terminal velocity, and have to do a well controlled maneuver to deaccelerate just before touchdown. I suspect that the margins in terms of "hovering time" probably are a bit less tight on the DC-1. Since this is apparently a routine maneuver in helicopter training, this would argue that the rocket powered analog might not be so hard as many people are making out. -- Bruce Dunn Vancouver, Canada Bruce_Dunn@mindlink.bc.ca ------------------------------ End of Space Digest Volume 15 : Issue 485 ------------------------------