The Grasshopper RLV consists of a Falcon 9 Stage 1 tank, a Merlin-1D engine, four steellanding legs, and a steel support structure. Carbon overwrapped pressure vessels (COPVs),which are filled with either nitrogen or helium, are attached to the support structure. The Merlin-1D engine has a maximum thrust of 122,000 pounds. The overall height of the GrasshopperRLV is 106 feet, and the tank height is 85 feet.The propellants used in the Grasshopper RLV include a highly refined kerosene fuel, called RP-1, and liquid oxygen (LOX) as the oxidizer. The Grasshopper RLV has a maximum operationalpropellant load of approximately 6,900 gallons; however, the propellant loads for any one testwould often be lower than the maximum propellant load. Even when the maximum propellantload is used, the majority of the propellant would remain unburned and would serve as ballast tokeep the thrust-to-weight ratio low.
Is this a test vehicle for a Lunar or Mars lander, or is Spacex going to be competing with Virgin Galactic?
Pretty obviously, this is to develop techniques for F9 first stages to recover on "land" which might include a barge at sea.
The Grasshopper RLV is a vertical takeoff and vertical landing (VTVL) vehicle. The highest altitude which the Grasshopper RLV would reach during launches conducted under an experimental permit is 11,500 feet above ground level (AGL). SpaceX would need to obtain a Letter of Authorization from the Robert Gray Army Radar Approach Control at Fort Hood to operate the Grasshopper RLV in the proposed airspace before any launches could commence.
QuotePretty obviously, this is to develop techniques for F9 first stages to recover on "land" which might include a barge at sea.So at least one F9 1st stage engine would have to be restartable after stage separation?
Although an experimental permit would authorize an unlimited number of launches, the FAA/AST must estimate the number of launches in order to analyze potential environmental impacts. In conjunction with SpaceX, the FAA/AST developed a conservative set of assumptions regarding the possible number of launches that could be conducted under any one experimental permit for the Grasshopper RLV at the McGregor test site. The FAA/AST has assumed that SpaceX would conduct up to 70 annual suborbital launches of the Grasshopper RLV under an experimental permit at the McGregor test site. This estimation is a conservative number and considers potential multiple launches per day and potential launch failures.
Launch Phase 3: Controlled-airspace VTVL (maximum altitude) The goal of Phase 3 is to verify the Grasshopper RLV’s ability to perform a VTVL mission at higher altitudes and higher ascent speeds and descent speeds. To achieve this, the maximum mission altitude would be increased from 670 feet incrementally up to 11,500 feet. The altitude test sequence likely would be 1,200 feet; 2,500 feet; 5,000 feet; 7,500 feet; and 11,500 feet. The maximum test duration would be approximately 160 seconds. The Grasshopper RLV would land back on the launch pad.
Under the No Action Alternative, the FAA/AST would not issue an experimental permit to SpaceX for operation of the Grasshopper RLV at the McGregor test site. Existing SpaceX activities would continue at the McGregor test site, which include engine testing for the Falcon 9 launch vehicle. SpaceX averages approximately five Merlin-1D tests per week as well as six Falcon 9 Stage 1 tests per year. The Falcon 9 is an expendable launch vehicle that uses RP-1 and LOX for propellants. Stage 1 of the Falcon 9 holds approximately 38,700 gallons of LOX and 24,900 gallons of RP-1, for a total of approximately 63,600 gallons of propellant. Stage 1 is powered by nine Merlin-1C engines, with each Merlin-1C engine producing 90,000 pounds of thrust. The Falcon 9 stage testing occurs on the tripod stand located at the site (see Exhibit 2-2 for general location). Additionally, SpaceX conducts hypergolic testing at the site, which occurs in an enclosed vacuum chamber.
Very interesting. I think this is directly related to this:Elon Musk: propulsively landing the first stageWhich is "tricky, but its very doable." Quote from: jedsmd on 09/24/2011 04:06 amQuotePretty obviously, this is to develop techniques for F9 first stages to recover on "land" which might include a barge at sea.So at least one F9 1st stage engine would have to be restartable after stage separation?Wouldn't it also mean this Merlin 1D should be able to gimbal?That would also answer the question how they would control a "re-entry-burn" (see: Elon Musk about shedding velocity by restarting the engines and a basic conceptial idea of re-entering the first stage, engines down first )Regards,arnezami
The Merlin 1D does gimbal.
Quote from: HMXHMX on 09/24/2011 04:35 pmThe Merlin 1D does gimbal.Oh sorry. I meant roll control. Stupid me.Falcon 1 had it (using the pump exhaust), but will this one falcon 1D have it? Or will they use roll control thrusters?Hmm. I guess that's still unanswered.
Well, they'll likely need a couple of RCS packs (Dracos) on there to do the turnaround for boostback, so presumably that RCS could also handle the roll control.Still, the sight a full-length F9 first stage landing vertically on a singular pillar of flame would be very Buck Rogers-esque...
Still, the sight a full-length F9 first stage landing vertically on a singular pillar of flame would be very Buck Rogers-esque...