- Parabolic Arc
- June 2, 2023
SpaceX is Developing a Reusable VTVL Rocket
Via my friend Clark Lindsey over at HobbySpace comes some rather startling news:
SpaceX is developing an 106-foot tall reusable vertical takeoff and vertical landing (VTVL) rocket called Grasshopper based upon the first stage of the Falcon 9 rocket. It has applied for an experimental permit to conduct a series of flights up to 11,500 feet at its engine testing facility in McGregor, Texas.
Here’s the description of the vehicle and its flight profile from a draft environmental impact assessment released by the FAA earlier this week:
The Grasshopper RLV consists of a Falcon 9 Stage 1 tank, a Merlin-1D engine, four steel landing 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 Grasshopper RLV 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 operational propellant load of approximately 6,900 gallons; however, the propellant loads for any one test would often be lower than the maximum propellant load. Even when the maximum propellant load is used, the majority of the propellant would remain unburned and would serve as ballast to keep the thrust-to-weight ratio low.
Flight Profile (Takeoff, Flight, and Landing)
The Grasshopper test program expected to be conducted under an experimental permit would consist of three phases of test launches, which would be performed in the sequence detailed below. SpaceX would repeat tests under each phase as necessary until SpaceX is ready to proceed to the next phase. Multiple test launches could occur each day during daytime hours only, and would be consistent with SpaceX’s lease with the City of McGregor. For example, SpaceX is prohibited from conducting engine tests between the hours of 12:00 a.m. and 7:00 a.m. per SpaceX’s lease with the City of McGregor.
Launch Phases 1 and 2: Below-controlled-airspace VTVL
The goal of Phase 1 is to verify the Grasshopper RLV’s overall ability to perform a VTVL mission. During a Phase 1 test, the Grasshopper RLV would be launched and ascend to 240 feet AGL and then throttle down in order to descend, landing back on the pad approximately 45 seconds after liftoff. The Grasshopper RLV would stay below Class E Airspace (700 feet AGL). In Phase 2, there would be slightly less propellant loaded, a different thrust profile, and the maximum altitude would be increased to 670 feet, still below Class E Airspace. The mission duration during Phase 2 is again approximately 45 seconds.
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.
One of SpaceX’s key goals is to be able to reuse the first stage of the Falcon 9, an aim that is considered crucial for its long-range business plan. Being able to fly a first stage back and land it intact would help the company accomplish its goal. On the initial two Falcon 9 launches, the first stages fell into the sea and were not in good enough shape to reuse.
Another intriguing possibility is SpaceX could enter the suborbital launch market. Masten Space Systems, Armadillo Aerospace and Blue Origin are all developing VTLV vehicles. XCOR and Virgin Galactic are building horizontal takeoff and horizontal landing vehicles for the same market.
SpaceX needs an experimental permit because McGregor is not a launch site and the rocket’s thrust is too high to be approved under a streamlined process. If the permit is approved, SpaceX is expected to take about three years to develop the Grasshopper with the number of flights possibly exceeding more than once per week:
The experimental permit would be valid for one year and would authorize an unlimited number of launches. The FAA/AST could renew the experimental permit if requested, in writing, by SpaceX at least 60 days before the permit expires. SpaceX anticipates that the Grasshopper RLV program would require up to 3 years to complete. Therefore, the Proposed Action considers one new permit and two potential permit renewals…
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. To support the Grasshopper RLV operations, SpaceX proposes to construct a launch pad and additional support infrastructure at the McGregor test site.
And here’s some interesting information about engine testing at the Texas site:
As mentioned in Section 2.2, SpaceX currently conducts engine tests at the McGregor test site. SpaceX averages approximately five Merlin-1D tests per week as well as six Falcon 9 Stage 1 tests per year.
13 responses to “SpaceX is Developing a Reusable VTVL Rocket”
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Too soon for SSTO…is it a re-useable first stage and/or suborbital single stage, as Blue Origin eventually wants?
…Duh. Maybe I should finish reading it, first.
As cool as this news is, can the sub-orbital market alone support the number of companies there are offering rides? (at least 6 with SpaceX) Even accounting for both tourist and research markets I still can’t imagine there will be enough demand to support anything more than the first few companies who get their vehicles out first, likely Virgin Galactic and XCOR.
I’m lovin’ this company! I wonder if they have in mind an eventual Mars mission for this VTVL vehicle?
SpaceX: they never fail to surprise us with new developments 🙂
Elon made some cryptic comments about SpaceX’s goal of reusability. He said that the booster did a belly flop on the atmosphere but that they had an idea of how to do it that works on paper. I wonder if this has something to do with that.
@Greg: as progressive as this company’s efforts are to ‘reduce the cost and increase accessibility to low earth orbit’ with innovative ideas like the VTVL vehicle (which by the way would most likely employ propulsive, and controls technology that has been in existence for some time), a mars mission is currently beyond their technical capability (and will be for the foreseeable future) — this company has not yet proven that they are capable of the infrastructure, technology development, and financial resources required to successfully complete a mission on the order of magnitude as an exploratory mars mission.
I suppose that aim of the work is not to use the Grasshopper for tourism but to get reusable first stage of Falcon 9.
I’m wondering how they are going to get it back from downrange. Boostback is one option, of course. Another option is a variation of the boostback such as Blue Origin seems to be doing.
The fins on the LV, that appear to be on backwards, look like they are located right around where the return CG would be what with a bunch of empty tanks – that would provide a level of “shuttlecock” stability. Then again, the unusual configuration of the base heat shield makes one tend to believe this is actually a return flight “nose” fairing. All this amounts to being a glideback phase following a boostback pulse. The “backwards” fins also look like they have control surfaces on what would be the trailing edges in the return flight direction. These are apparent in some of the recent launch photos.
Wow, not only testing Verticle landing but the new Merlin 1D with higher max thrust that can throtle 70-100%. Looks like re-usability of first stage is progressing anlong with the technology for a Mars Lander/Launcher. Got to love private enterprise.
It is just a pity Congress can not see past the pork barrel to the potential benifits or private enterprise.
Although SpaceX could not yet do it on there own they are a lot closer than NASA and the expensive waste of SLS and MPCV.
Combine SpaceX and Bigelow and you have Launch with Dragon, Habitat with Bigelow, landing on Mars with Dragon or the vertical lander, Launch from Mars and then return to Earth with Dragon. All that is missing is an interplanetary propulsion drive and radiation shielding, who can provide that?
I do not believe that Greg was suggesting that SpaceX was going to Mars next year. Musk has said all along, that he intends to go to Mars around 2025. That is 15 years from now. They have PLENTY of time to prove that “they are capable of the infrastructure, technology development, and financial resources required to successfully complete a mission on the order of magnitude as an exploratory mars mission”.
Personally, I suspect that all of these VTVLs are going to be on the moon within a decade and mars about 5 years later. By being able to do a a FULL VTVL on earth up to 100 miles AND BACK UNDER FULL POWER, well, the moon is at 1/6 G, and lunar orbit for apollo was 100 miles. IOW, this craft should have NO difficulty landing on the moon and later mars.
Very nice to see the movement forward on Grasshopper. I like your thoughts ReusablesForever. Elon, as any great engineer would, always considers and exploits every possible option. Perhaps downrange pickup isn’t the only option being evaluated. The couple you mention make a lot of sense. Would be efficient to immediately get all the pieces back to one spot for refurbishment. Go SpaceX. Go everyone who sees the infinite resources of space and are making efforts to exploit those limitless resources for the benefit of all.