I recently got into Velcro Rockets fun again. My idea was : let's try to do a rocket with Deltaglider-like technology.
Of course I wanted a reusable SSTO, at this technology level.
So the thing is equipped with 5 DG-engines (200 kN x5, Isp 40,000, IspSL 30,000). I found it was OK for a liftoff mass of 40-50 tons. I set an empty mass of 25 tons and a propellant mass of 20 tons.
I chosen a 6-meters diameters because I wanted it to be able to carry large payloads. In that case, an adapter and a fairing would be secured on top of the launcher, then detached before re-entry. Still, even in that configuration, the rocket would keep its aerodynamic shape, even at the cost of some volume lost (could be used for expendable upper stage engines or tanks anyway). There is a landing gear that is of course supposed to be retractable. The black paint is supposed to be made of thermal coating, and there would be thermal tiles on the nose, on the "engines cases" and on the leading edge of the fins, the most exposed parts to heat.
The way I see things, the lower part would be occupied by the engines and the nuclear fusion devices. Above would be the Unobtainium propellant tank. In fact there is plenty of room for a propellant much less dense (and way cheaper, like LH2 ?) than in any DG, where space is precious.
The biggest challenge I face is unsurprisingly re-entry. I've entered correct cross sections, and, as espected given its shape, the thing behaves like a missle and performs a ballistic re-entry, enduring 8-9 G in low atmosphere. That's not a problem for an unmanned vehicle. What worries me more are the 800 kPa of dynamic pressure recorded at the peak of the deceleration. It seems enormous to me and I fear it would crush anything, today's rockets don't go much above 40 kPa at maxQ. Also, there is very little time to orient properly the rocket and perform a powered landing.
So I wonder what's the best solution. A fully powered deorbit and landing seems crazy regarding fuel consumption, even with that kind of tech : the engines would be very exposed. I'm thinking about some massive airbrakes that would deploy between the "engines cases", increasing the frontal cross section. But I guess it would not be possible to deploy them above the worst part of the re-entry. Maybe it would help to deploy them from orbit, retract them when the DNP becomes intense, then deploy them again when things calm down.
I'm wondering what are your 2 cents about this very hypothetical spacecraft engineering problem. Note that the screenshots depict a "test article", with non-retractable landing gear and no upper stage, payload or fairing. :hmm:
Experiments showed me that the propellant mass is correct, I can achieve orbit and have enough to spare for a powered landing after the ballistic re-entry (knowing this one is carrying no payload).
Re-entry :
Of course I wanted a reusable SSTO, at this technology level.
So the thing is equipped with 5 DG-engines (200 kN x5, Isp 40,000, IspSL 30,000). I found it was OK for a liftoff mass of 40-50 tons. I set an empty mass of 25 tons and a propellant mass of 20 tons.
I chosen a 6-meters diameters because I wanted it to be able to carry large payloads. In that case, an adapter and a fairing would be secured on top of the launcher, then detached before re-entry. Still, even in that configuration, the rocket would keep its aerodynamic shape, even at the cost of some volume lost (could be used for expendable upper stage engines or tanks anyway). There is a landing gear that is of course supposed to be retractable. The black paint is supposed to be made of thermal coating, and there would be thermal tiles on the nose, on the "engines cases" and on the leading edge of the fins, the most exposed parts to heat.
The way I see things, the lower part would be occupied by the engines and the nuclear fusion devices. Above would be the Unobtainium propellant tank. In fact there is plenty of room for a propellant much less dense (and way cheaper, like LH2 ?) than in any DG, where space is precious.
The biggest challenge I face is unsurprisingly re-entry. I've entered correct cross sections, and, as espected given its shape, the thing behaves like a missle and performs a ballistic re-entry, enduring 8-9 G in low atmosphere. That's not a problem for an unmanned vehicle. What worries me more are the 800 kPa of dynamic pressure recorded at the peak of the deceleration. It seems enormous to me and I fear it would crush anything, today's rockets don't go much above 40 kPa at maxQ. Also, there is very little time to orient properly the rocket and perform a powered landing.
So I wonder what's the best solution. A fully powered deorbit and landing seems crazy regarding fuel consumption, even with that kind of tech : the engines would be very exposed. I'm thinking about some massive airbrakes that would deploy between the "engines cases", increasing the frontal cross section. But I guess it would not be possible to deploy them above the worst part of the re-entry. Maybe it would help to deploy them from orbit, retract them when the DNP becomes intense, then deploy them again when things calm down.
I'm wondering what are your 2 cents about this very hypothetical spacecraft engineering problem. Note that the screenshots depict a "test article", with non-retractable landing gear and no upper stage, payload or fairing. :hmm:
Experiments showed me that the propellant mass is correct, I can achieve orbit and have enough to spare for a powered landing after the ballistic re-entry (knowing this one is carrying no payload).
Re-entry :
Last edited: