View Single Post
  #8  
Old 02-23-2019, 01:16 AM
blackshire's Avatar
blackshire blackshire is offline
Master Modeler
 
Join Date: Jan 2009
Location: Fairbanks, Alaska
Posts: 6,507
Default

Quote:
Originally Posted by tbzep
Those thruster nozzles are related to our hobby. Back in the mid to late 90's, some friends down in Huntsville decided to do an amateur high altitude project. It was a rockoon (balloon launched rocket). My buddy Jim built the motor hardware and we cast a few propellant grains for the hybrid. However, they wanted it to be a "dirt rocket". I.E. use tar for the propellant grain. Jim's grains were more potent, but the tar was just something they wanted to use because somebody said it wouldn't work. We did test firings at Tim Pickens' (eventual designer of Spaceship One motor) parents' land. The rocket was successfully tested via a ground launch in Manchester, TN that used every bit of the 15k waiver. The balloon was eventually launched off a barge in the Gulf and the rocket made a successful flight, but I don't recall the altitude. It was in Guinness as the highest amateur flight for a few years.

Now to relate it to the space program's reaction control thrusters. A lot of old hardware from NASA ended up in a couple of junkyards in Huntsville. Tim found some of them and used an expansion bell from one to make a mold for the dirt rocket's high altitude motor. The more I think about it, I'm pretty sure it was from Surveyor instead of Apollo, but it's still cool as heck. Maybe Tim, Dan or one of the old crew is lurking and can remember it better than me.
Wow--talk about melding (or molding, in this case) past and present! Those Surveyor verniers (three per lander) stabilized the spacecraft while the big, spherical STAR-37 solid motor (a derivative of which served as the Thor-Burner II and Thor-Burner IIA second stage: https://en.wikipedia.org/wiki/Thor-Burner ) did the "heavy lowering," then--after the spent STAR-37 was jettisoned at about 6 miles up and 250 miles per hour--braked the lander to 0 mph about 13 feet above the surface, then shut down. The 13' free-fall was equivalent to just a 2' one on Earth, whose impact the landing gear shock absorbers and crush-able footpads (which were never compacted, to my knowledge) easily absorbed. Also:

The World War II-era Private A and/or Private F used asphalt-fueled composite solid propellant. It worked well, but got very soft at tropical/desert temperatures and cracked at very cold temperatures; tar, I imagine, is more physically stable over such a temperature range.
__________________
Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
http://www.lulu.com/content/paperba...an-form/8075185
http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
NAR #54895 SR
Reply With Quote