Re: [ERPS] A Rocket A Day

[Ken Doyle]

John,   Yes, Doug appears to be trolling..     I designed, fabricated, and operated the propellant loading system for the Roton ATV and the rotor test stand.  Mike was there during much of the ATV HTP loadings, usually acting as safety man with the water hose.  Doug was never there, and knows not of what he speaks..   We never had a problem or incident with the HTP loading.  I'd say that operating the peroxide concentrator plant was riskier, as it was operated many more hours through a lot of hot and windy Mojave Desert days.  Both Johnny and Mike did great work.   The "trick" with handling HTP is material selection of all components in the system, and cleanliness.  The same cleanliness procedures as for LOX systems were applied to the tanks and plumbing during fabrication, and efforts were made to passivate the materials.  We also ran some 70% through the systems prior to using the 85+% HTP.  I always avoided leaving any HTP in the plumbing runs, and built the systems to accomodate purging and pressure relief.  The purging medium was distilled-quality water.  Because of the dusty environment, nothing was poured through open air.   Essentially, safety measures consisted of splash protection, and having a safety man ready to fire the water hose at anyone who gets splashed.  Hazardous waste disposal of spilled HTP was a non-issue; when it hit the ground in Mojave, it went right to steam.   The equipment and loading methodology:  I had 4ea 500 gallon polyethylene tanks on dual-axis trailers.  (That much HTP is heavy.)  We produced into the tanks out of the Concentration plant.  I mounted air-powered diaphragm pumps on each trailer, above the tank top level and plumbed for full drainage and purge capability.  The pumps were made from PVDF, as I recall.  The plumbing on the trailer/tanks was reinforced PVC clear hose, with stainless, teflon, and PVC fittings.  The vents were through filters sized to keep the Mojave dust out.  We parked them in shade, and had some reflective mylar bubble insulation around the tanks.  At the end of every HTP transfer, filtered air was pumped through the plumbing to mostly empty it, followed by a distilled water purge and then more filtered air.  A few of the components in the system were not compatible enough to leave HTP sitting in them, but were not a problem during transfer operations so long as they were left clean and dry afterwards.  I got a lot of material selection guidance from the very experienced Test Site engineer.   For making the loading connection into the ATV (and the prior Rotor test stand), I had some dripless, self-sealing all-stainless quick-disconnects at the end of the trailer/tank hose and built into the ATV.   The air-powered diaphragm pumps worked great, and it was nice to be able to throttle the flow by controlling the air to the pump.  We could start out slow and cautious and low-pressure, and let 'er rip when certain that we had no leakage.   The HTP plumbing in the ATV was of 6061 aluminum tubing with stainless fittings.  (Some aluminum alloys are not compatible with HTP.)  I don't doubt that the fittings and tubing have some corrosion between them by now, sitting in the hangar in Mojave..  (At the time, the pressure was on, and we weren't worried about long-term corrosion problems.)  The HTP tank inside the ATV was a 400 gallon Structural North America fiberglass-wound polyethylene model.  We used most of it's safety factor during ATV flight.  We used a nitrogen pressurized system, at about 450 psi.  On/Off control was via pneumatic actuated stainless/teflon ball valves.  Throttle control was through one of two redundant "V-cut" ball valves positioned below the rotating union at the rotor head.  The rotating union had provisions to keep the HTP and the liquid catalyst away from each other even if a seal were to fail.  The tubing within the blades was 6061-T6 for the HTP.  The throttle valves were positioned by rotary servo-actuators.  Direct pilot control of the flow was very tricky and all-consuming of attention, so we developed a throttle control system involving RPM sensing, mechanical feedback to the pilot, and a microcontroller running a PID loop to positon the throttle valve actuators and pilot-feedback motors.   The hardware-in-the-loop simulator needed to know what the HTP flow and thrust from the tip-rockets would be at any throttle or collective setting, RPM, and tank pressure.  The formula to predict this was pretty involved; lots of non-linearities and variables.   In summation....   at Rotary, through careful design and cleanliness and procedure, we did achieve routine and safe handling of thousands of pounds/gallons of HTP, in hot and dusty conditions, without incident.    The liquid catalyst that we used was much more of a pain in the ass to deal with.     Good luck with getting FMC to sell to you.  They set up a lot of hoops for us to jump through.  I wish I could help you more with, but I didn't handle that.   Ken Doyle   >My chief mechanic, Mike Laughlin, did much of the HTP loading and >unloading for the propulsion testing for the Roton ATV; his assistant, >Johnny Hernandez, operated the peroxide concentrator plant.  They didn't >like those jobs *at all*, involving hundreds of pounds of 85% HTP. Ok, but *WHY* didn't they like those jobs at all?  Did it just creep them out?  Personally, I wouldn't want to run the concentrator, but I don't see what the big deal with loading the propellent is.  BTW, what was the loading methodology?  Pump/vacuum from drums, or a single mid-sized tank? >LOX is cheap, readily available, high performance, and is routinely >handled safely by thousands of workers around the world every day.  HTP >is not. Doug is trolling. :-) However, the availability is an issue.  I finally talked to FMC again today, and they are pretty skittish sounding.  Steven Rhine commented that *ALL* of their customers are government contractors, and they will have to decide if they want to sell to a commercial customer. I will be rather perturbed if they decline to sell to us. John Carmack