<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div><div style="-webkit-tap-highlight-color: rgba(26, 26, 26, 0.296875); -webkit-composition-fill-color: rgba(175, 192, 227, 0.230469); -webkit-composition-frame-color: rgba(77, 128, 180, 0.230469); ">Definitely not an expert, but here's my attempt since you included VT Aerospace guys in general. :-)</div><div style="-webkit-tap-highlight-color: rgba(26, 26, 26, 0.296875); -webkit-composition-fill-color: rgba(175, 192, 227, 0.230469); -webkit-composition-frame-color: rgba(77, 128, 180, 0.230469); "><br></div><div style="-webkit-tap-highlight-color: rgba(26, 26, 26, 0.296875); -webkit-composition-fill-color: rgba(175, 192, 227, 0.230469); -webkit-composition-frame-color: rgba(77, 128, 180, 0.230469); ">I can't speak for solid boosters, but on the liquids I've interacted with there are hydraulic struts (controlled with some of either the LOx or the RP-1 fuel in that case, can't remember which one) to gimbal the engine; I'd imagine something vaguely similar with a solid nozzle, just shoving it around here and there. Although obviously they wouldn't be able to rely on fuel to operate it...</div><div style="-webkit-tap-highlight-color: rgba(26, 26, 26, 0.296875); -webkit-composition-fill-color: rgba(175, 192, 227, 0.230469); -webkit-composition-frame-color: rgba(77, 128, 180, 0.230469); "><br></div><div style="-webkit-tap-highlight-color: rgba(26, 26, 26, 0.296875); -webkit-composition-fill-color: rgba(175, 192, 227, 0.230469); -webkit-composition-frame-color: rgba(77, 128, 180, 0.230469); ">As for varying thrust, you're right that solids are either "on or off," but from what I understand the internal "shape" of the solid fuel can be varied to alter burn rates--sounds like they did this in the Space Shuttle SRBs to account for different loading cases along the flight profile. Something about 11-point stars and truncated cones... See here: <span style="font-family: '.HelveticaNeueUI'; font-size: 15px; line-height: 19px; white-space: nowrap; -webkit-text-size-adjust: none; "><a href="http://en.wikipedia.org/wiki/Space_Shuttle_Solid_Rocket_Booster#Propellant">http://en.wikipedia.org/wiki/Space_Shuttle_Solid_Rocket_Booster#Propellant</a></span><br><br>Anyway, just my 2 cents... Anyone else feel free to chime in with more accurate/correct details.<br></div></div><div style="-webkit-tap-highlight-color: rgba(26, 26, 26, 0.296875); -webkit-composition-fill-color: rgba(175, 192, 227, 0.230469); -webkit-composition-frame-color: rgba(77, 128, 180, 0.230469); "><br></div><div style="-webkit-tap-highlight-color: rgba(26, 26, 26, 0.296875); -webkit-composition-fill-color: rgba(175, 192, 227, 0.230469); -webkit-composition-frame-color: rgba(77, 128, 180, 0.230469); ">Brandon Smith<br><div><br></div><div>Sent from my mobile. Please forgive any typos.</div></div><div style="-webkit-tap-highlight-color: rgba(26, 26, 26, 0.296875); -webkit-composition-fill-color: rgba(175, 192, 227, 0.230469); -webkit-composition-frame-color: rgba(77, 128, 180, 0.230469); "><br>On Sep 8, 2013, at 12:32 AM, Thomas Weeks <<a href="mailto:tweeksjunk2@theweeks.org">tweeksjunk2@theweeks.org</a>> wrote:<br><br></div><blockquote type="cite" style="-webkit-tap-highlight-color: rgba(26, 26, 26, 0.296875); -webkit-composition-fill-color: rgba(175, 192, 227, 0.230469); -webkit-composition-frame-color: rgba(77, 128, 180, 0.230469); "><p style="margin: 0px; ">BTW...</p><p style="margin: 0px; "></p><p style="margin: 0px; ">> Hey Dr. S, or other VT Aerospace Guys..</p><p style="margin: 0px; ">></p><p style="margin: 0px; ">> So I've been watching LADEE footage from the launch last night and was just</p><p style="margin: 0px; ">> wondering.. how do they stabilize large rockets like LADEE that obviously</p><p style="margin: 0px; ">> have zero visible fins? Ballistically (if it flew passively) it should go</p><p style="margin: 0px; ">> end over end.. no?</p><p style="margin: 0px; "></p><p style="margin: 0px; ">Here's the photo I was staring at when I posed these questions:</p><p style="margin: 0px; "><a href="http://www.nasa.gov/content/ladee-launches-from-nasa-wallops/">http://www.nasa.gov/content/ladee-launches-from-nasa-wallops/</a></p><p style="margin: 0px; "></p><p style="margin: 0px; ">The boosters sections look as smooth as a Sono-Tube(tm).</p><p style="margin: 0px; "></p><p style="margin: 0px; ">Just made me start wondering...</p><p style="margin: 0px; "></p><p style="margin: 0px; ">Tweeks</p><p style="margin: 0px; "></p><p style="margin: 0px; "></p><p style="margin: 0px; ">></p><p style="margin: 0px; ">> Are there ANY control surfaces on the LADEE boosters? I imagine they would</p><p style="margin: 0px; ">> have to either use some sort of active vectored thrust, control surfaces,</p><p style="margin: 0px; ">> or spin stabilization to keep it pointed up... no?</p><p style="margin: 0px; ">></p><p style="margin: 0px; ">> And what about controlling the % thrust? They're using solid propulsion</p><p style="margin: 0px; ">> motors (sort of like our HP ACP motors)... which are usually either 100%</p><p style="margin: 0px; ">> on or burned out/off right? Do they have some sort of burn-rate or</p><p style="margin: 0px; ">> oxidizer flow rate controls in their motors too?</p><p style="margin: 0px; ">></p><p style="margin: 0px; ">> Hmm..</p><p style="margin: 0px; ">></p><p style="margin: 0px; ">> Tweeks</p><p style="margin: 0px; "></p></blockquote><blockquote type="cite" style="-webkit-tap-highlight-color: rgba(26, 26, 26, 0.296875); -webkit-composition-fill-color: rgba(175, 192, 227, 0.230469); -webkit-composition-frame-color: rgba(77, 128, 180, 0.230469); ">_______________________________________________<br>NRVR mailing list<br><a href="mailto:NRVR@nrvr.org">NRVR@nrvr.org</a><br><a href="http://nrvr.org/mailman/listinfo/nrvr">http://nrvr.org/mailman/listinfo/nrvr</a></blockquote></body></html>