blackshire
04-18-2012, 07:35 AM
Hello All,
Below are links to information on two subjects for *scale* conical boost-gliders which, having low lift/drag ratios, wouldn't glide beyond the boundaries of small flying fields. Axisymmetric conical gliders such as these would fly best with an offset Center of Gravity (with the CG not in line with the centerline axis, but to one side). To more easily trim such models for good gliding characteristics, the trim ballast could be movable, capable of being slid forward and backward in a track and then being locked into position with a set screw.
As the Centuri Technical Information Report TIR-24 "Model Rocket Lifting Bodies" (see: http://sargrocket.org/Documents/Centuri/tir-24.pdf ) shows, the offset CG gives a conical lifting body the proper pitch trim to provide aerodynamic lift for gliding, and it also provides the analog of dihedral in the wings of a conventional airplane (the triangular cross-sections of conical model rocket lifting bodies such as the X-24 Bug and the HL-20 provide actual dihedral). Also, space capsules that could/can maneuver during re-entry such as Gemini, Apollo, Soyuz, Zond, and Dragon also had/have offset centers of gravity to provide lift. Here are the links:
[1] The BGRV (Boost Glide Re-entry Vehicle, see: www.astronautix.com/craft/boohicle.htm and www.daviddarling.info/encyclopedia/B/BGRV.html ) was a test vehicle for a maneuverable ICBM re-entry vehicle that was launched aboard Atlas F missiles. The BGRV used thrusters and (I think, judging by the appearance of its aft end) movable hinged rectangular drag flaps. Several test flights in the late 1960s demonstrated its ability to suddenly maneuver to "fall short" as well as to strike targets out of the plane of (to either side of, that is) its ballistic trajectory.
[2] The Alpha Draco test vehicle (see: http://en.wikipedia.org/wiki/Alpha_Draco and www.robsv.com/cape/c10ad.html ) was a two-stage suborbital boost-glide re-entry test vehicle that validated the technology in 1959. It would make a nice scale model as a complete vehicle (booster + re-entry vehicle). In addition, here are links to documents on early maneuverable re-entry vehicles, including the BGRV and Alpha Draco (see: http://books.google.com/books?id=lN0w6X0PG3QC&pg=PA38&lpg=PA38&dq=boost+glide+reentry+vehicle+bgrv&source=bl&ots=DyCA2eGfts&sig=y3XCZWbPYEgLhYLdkKx04qt49yo&hl=en&sa=X&ei=AK6OT4KeMsXPiALwzpn_Ag&ved=0CB0Q6AEwADgU and https://docs.google.com/viewer?a=v&q=cache:XDj1n6LbJZAJ:www.afa.org/mitchell/reports/MP6_Hypersonics_0610.pdf+boost+glide+reentry+vehicle+bgrv&hl=en&gl=us&pid=bl&srcid=ADGEESj8ZQ02uANiZEju82LoIJhdcT5HjXe8z6KcQf7KuU3sQYM5u1ia8aoKNPTnL1CypaIXTPbbpqXL95XJcLuW0UnJLmjtaUY8nOjVrZg_7SQGubhaavNneDLHbliSe4YIJ3RGT1IN&sig=AHIEtbTvJOO-BblbSWiRmru6CerRhjgDRA )
I hope this information will be helpful.
Below are links to information on two subjects for *scale* conical boost-gliders which, having low lift/drag ratios, wouldn't glide beyond the boundaries of small flying fields. Axisymmetric conical gliders such as these would fly best with an offset Center of Gravity (with the CG not in line with the centerline axis, but to one side). To more easily trim such models for good gliding characteristics, the trim ballast could be movable, capable of being slid forward and backward in a track and then being locked into position with a set screw.
As the Centuri Technical Information Report TIR-24 "Model Rocket Lifting Bodies" (see: http://sargrocket.org/Documents/Centuri/tir-24.pdf ) shows, the offset CG gives a conical lifting body the proper pitch trim to provide aerodynamic lift for gliding, and it also provides the analog of dihedral in the wings of a conventional airplane (the triangular cross-sections of conical model rocket lifting bodies such as the X-24 Bug and the HL-20 provide actual dihedral). Also, space capsules that could/can maneuver during re-entry such as Gemini, Apollo, Soyuz, Zond, and Dragon also had/have offset centers of gravity to provide lift. Here are the links:
[1] The BGRV (Boost Glide Re-entry Vehicle, see: www.astronautix.com/craft/boohicle.htm and www.daviddarling.info/encyclopedia/B/BGRV.html ) was a test vehicle for a maneuverable ICBM re-entry vehicle that was launched aboard Atlas F missiles. The BGRV used thrusters and (I think, judging by the appearance of its aft end) movable hinged rectangular drag flaps. Several test flights in the late 1960s demonstrated its ability to suddenly maneuver to "fall short" as well as to strike targets out of the plane of (to either side of, that is) its ballistic trajectory.
[2] The Alpha Draco test vehicle (see: http://en.wikipedia.org/wiki/Alpha_Draco and www.robsv.com/cape/c10ad.html ) was a two-stage suborbital boost-glide re-entry test vehicle that validated the technology in 1959. It would make a nice scale model as a complete vehicle (booster + re-entry vehicle). In addition, here are links to documents on early maneuverable re-entry vehicles, including the BGRV and Alpha Draco (see: http://books.google.com/books?id=lN0w6X0PG3QC&pg=PA38&lpg=PA38&dq=boost+glide+reentry+vehicle+bgrv&source=bl&ots=DyCA2eGfts&sig=y3XCZWbPYEgLhYLdkKx04qt49yo&hl=en&sa=X&ei=AK6OT4KeMsXPiALwzpn_Ag&ved=0CB0Q6AEwADgU and https://docs.google.com/viewer?a=v&q=cache:XDj1n6LbJZAJ:www.afa.org/mitchell/reports/MP6_Hypersonics_0610.pdf+boost+glide+reentry+vehicle+bgrv&hl=en&gl=us&pid=bl&srcid=ADGEESj8ZQ02uANiZEju82LoIJhdcT5HjXe8z6KcQf7KuU3sQYM5u1ia8aoKNPTnL1CypaIXTPbbpqXL95XJcLuW0UnJLmjtaUY8nOjVrZg_7SQGubhaavNneDLHbliSe4YIJ3RGT1IN&sig=AHIEtbTvJOO-BblbSWiRmru6CerRhjgDRA )
I hope this information will be helpful.