A lot of propane was used to warn the engine. Was this sufficient to lift the rocket off the launch tower?
What would be the best application for an engine like this? Some mission where you badly want to avoid boil-off? A return mission from the surface of Venus or Mercury perhaps?
So is this another solution looking for a problem? Or do they have some particular use in mind for it?
If the fuel has no casing, then how does it maintain it's length? Would the stage have a thin cylindrical exterior (basically a fairing) that would attach the engine section to the part they is mated to the second stage (and/or the payload)?
It's basically a solid motor with a solid fuel tank.You would need at least a high power press, and an aero framework round it at least. The press can be entirely tensile which helps somewhat in terms of lightness.The press needs to be high power - of the same sort of power as turbopumps for an equivalent thrust liquid engine, because it's doing the same thing - forcing an unpressurised fuel into a pressurised combustion chamber.
Quote from: speedevil on 08/27/2018 10:00 amThe press needs to be high power - of the same sort of power as turbopumps for an equivalent thrust liquid engine, because it's doing the same thing - forcing an unpressurised fuel into a pressurised combustion chamber.Turbo-pumps can be powered by the fuel's combustion. How do they harness the solid fuel's combustion to power the press? Turbine again -ie. "turbo-press"?
The press needs to be high power - of the same sort of power as turbopumps for an equivalent thrust liquid engine, because it's doing the same thing - forcing an unpressurised fuel into a pressurised combustion chamber.
Gee, could this lead to technology improvements in the fireworks market? If this is easier to scale down, then could it be used beneficially in retropropulsion/braking solid motors like those in the Soyuz or the New Shepard capsules?
Quote from: jbenton on 08/27/2018 12:17 amIf the fuel has no casing, then how does it maintain it's length? Would the stage have a thin cylindrical exterior (basically a fairing) that would attach the engine section to the part they is mated to the second stage (and/or the payload)?It's basically a solid motor with a solid fuel tank.You would need at least a high power press, and an aero framework round it at least. The press can be entirely tensile which helps somewhat in terms of lightness.The press needs to be high power - of the same sort of power as turbopumps for an equivalent thrust liquid engine, because it's doing the same thing - forcing an unpressurised fuel into a pressurised combustion chamber.
In principle you could run a turbine from a gas generator operated at a lower temperature, or tap some of the exhaust gas and run it through a cooling system similarly, or try to make a very high temperature turbine to operate in the complex flow conditions of solid exhaust going through it.It may be considerably easier and lighter to just to use an electric motor and batteries.In principle, you can sidestep some of this if you operate it discontinuously - allow the combustion chamber pressure to decay before replacing the fuel in a sealed container, or only advance the fuel during cyclic periods of low pressure. Both greatly impact efficiency and have other problems.
The way I read the article, the engine can be thought of as an expander cycle for a solid rocket. The heat of combustion will need to be harnessed to affect a phase change in the solid fuel into a gas or liquid, where it then is fed into the combustions chamber. Because the area of the heat exchange surface scales linear to the radius of the fuel rod, vs the volume of fuel scale to the square, it favors smaller engines ( similar to the expander cycle scaling issues). I also think the engine could operate as self pressurizing if as the engine climbs up the fuel rod, it also seals off the heat exchanger & combustions chamber. I think of a sliding "O" ring going up the fuel rod, with the pressurized engine section on one side & the bulk fuel rod on the other side. ( possible failure mode) I visualize the engine segment crawling up a shaft of propellent until it reaches a staging point, or the PAF if on a second stage. I would think engine shutoff would also be able to be engineered so that fuel residuals are near zero.
Quote from: speedevil on 08/27/2018 10:00 amThe press needs to be high power - of the same sort of power as turbopumps for an equivalent thrust liquid engine, because it's doing the same thing - forcing an unpressurised fuel into a pressurised combustion chamber.How do you mean "entirely tensile"?
It can be a winch, with ropes or cables to the far end of the fuel grain, for structural efficiency.
Jan 10, 2024After a rocket uses up its fuel, the tank generally just becomes dead weight, but a prototype rocket that burns its own fuselage as propellant could solve that problem. A team of engineers has built a prototype of one of these “autophage engines” for the first time, which could free up capacity for transporting more important science projects and supplies into space.
Oct 21, 2020 #starship #elonmusk #spacexA team of engineers from the University of Glasgow and Oles Honchar Dnipro National University in Ukraine has built and test-fired a new style of "autophage" rocket engine that eats its own structure from the bottom up during the flight. They believe it could lead to cheaper, more efficient, and less wasteful small satellite launches.Rather than using a heavy tank to store its fuel, the autophage rocket's main structure is a cylindrical propellant rod consisting of solid, strong plastic fuel on the outside with a core of powdered oxidizer.As the rod is pushed into the hot engine, it gets vaporized, producing thrust via exhaust gases as well as more heat to burn the next bit of the propellant rod. So the rocket gets shorter as it eats itself from the bottom up.Many solid fuel motors, the researchers say, don't have the capability of being throttled. With the autophage engine, that's not a problem. You simply increase the speed at which you're feeding the propellant rod if you want more thrust.
ETV Phase 1 - Preliminary Design Review of the Economical Transfer Vehicle, Meridian Space Command x Alpha Impulsion (France) - £150,000This project will advance the development of the Economical Transfer Vehicle (ETV), the world’s first “self-eating” spacecraft. he ETV is a next-generation logistics and payload-hosting spacecraft powered by an autophage engine that actively consumes its own structural tank during flight. Designed for high delta-V missions, it will transport payloads across Earth orbits and beyond, supporting future in-orbit servicing, infrastructure, and deep space logistics.
As part of the PDR, Alpha has teamed up with Meridian to study how the propulsion system could effectively create a cheaper OTV, by reducing the overall weight necessary to reach further orbits. The study will assess both the technical feasibility and economic viability of the proposed ETV.On the technology front, Alpha and Meridian have a good idea already of what a typical ETV mission could look like.The ETV is expected to have a payload capacity of up to 50 kg, with a total launch mass of about 250 kg.The spacecraft is expected to have a Delta-v capability of around 4.5 km/s, giving the ETV the ability to change its inclination by up to 30 degrees within LEO. It can also reach MEO, GEO, and even lunar orbits.The idea is to have the ETV hitch a ride on a cheap rideshare flight to LEO or SSO and then power itself to its final trajectory, reducing its total mass the entire way.
