Reuability Methods for Rockets:

Void · 2019-03-21 16:03:50

I hesitate to start a new topic, but there is this, method proposed by Europe:
https://www.bing.com/news/search?q=Spac … &FORM=EWRE
I guess we can maybe consider calling it something like "Additive methods after launch, for recovery of hardware".
Quote:

Germany begins reusability study to capture rockets in midair and land them with a plane
by Caleb Henry — March 21, 2019

It seem to be kin to Vulcan.

In a similar to those methods, I have thought about having zero gee labs in orbit that aero-burn down after completing their work, and where the lab is approached by a air breathing drone, which attaches a parachute for instance. Ocean landing is the probable method, but also, with a parachute/glider, and a drone to push it, you might navigate the load to a selected location. Then if you do have a parachute/parafoil, perhaps ground engines may help in bringing it down safely.

I hope the Germans/Europeans succeed. I am guessing that it will depend on purpose what method is the best. So, likely many methods for different purposes. I like it.

Done.

Last edited by Void (2019-03-21 16:09:08)

louis · 2019-03-22 05:55:30

So either a v. big plane or a small rocket?

Void wrote:

I hesitate to start a new topic, but there is this, method proposed by Europe:
https://www.bing.com/news/search?q=Spac … &FORM=EWRE
I guess we can maybe consider calling it something like "Additive methods after launch, for recovery of hardware".
Quote:
Germany begins reusability study to capture rockets in midair and land them with a plane
by Caleb Henry — March 21, 2019
It seem to be kin to Vulcan.
In a similar to those methods, I have thought about having zero gee labs in orbit that aero-burn down after completing their work, and where the lab is approached by a air breathing drone, which attaches a parachute for instance. Ocean landing is the probable method, but also, with a parachute/glider, and a drone to push it, you might navigate the load to a selected location. Then if you do have a parachute/parafoil, perhaps ground engines may help in bringing it down safely.
I hope the Germans/Europeans succeed. I am guessing that it will depend on purpose what method is the best. So, likely many methods for different purposes. I like it.
Done.

Void · 2019-03-22 10:44:48

Louis,

Yes, of course you are correct. There are limitations. I do think SpaceX, has a very good grasp. I hope that the 1st stage of New Glen will be an advancement as well. I am looking for achievement myself, being rather an underachiever. I can appreciate it.

By the way the absence of SpaceNut is sadly noted. I hope all can be well in that regard.

As best I can comprehend, we are in the equivalent of the Cambrian Explosion in the evolution of space flight. It therefore is not at all unwelcome to see, various tries at achievement in that regard. Not for me anyway. Natural truth will sort things out ultimately, hopefully in a correct manner to give us the best possible options for all possible modes of needed capabilities. Nature being a bitch really in the end, we also need to seek to modify the outcome with a bit of perception. Nature takes a very long time to get to the point, and can actually miss an important turn. That is why we have grey matter.

My grey matter is rather a small pudding. And not the best I am sure, but I will do the level of lifting that I can for the cause. I don't expect to never be wrong. I have to hope that I can learn something better. That is a reward, perhaps I should not have, but that I desire.

So, which is the more important? Conserve propellant, or reuse hardware? Economics of course is a judge, also capability is a judge. If you can get 90% to a target objective, that is admirable, but does not pay the bills.

So, heat shields then, Elon Musk and SpaceX have not said all. Probably still they seek truth on this issue. Also don't want to show their hand I should think and hope.

So far though they seem to indicate that pica tiles might be the first game, and stainless steel on the leeward side. They will study erosion and then apply evaporative cooing, it would seem, where it is required to reduce erosion of the tiles. So, are they going to expose a stainless steel surface with evaporative cooling, or will they involve pica or some other ceramic tile, with pores? These are questions that run through my head.

That is a bit scary, as if you put a pressurized liquid under the tile, do you risk pushing the tile off from the structure?

One thing that pleases me is that they intend to apply active cooling only to reduce tile erosion. They do not intend it to save the ship from calamity. So, I feel more at ease about it.

So, from here you should consider what I present as more questions than statements of certainty.

So, is it ablation, evaporative cooling, or heat sinking or a combination in the end?

It would seem that for now at least, 1st stages of rockets, may either be aerobic planes, or true rockets, and parts or the whole may be recovered by various means. The balance between the conservation of propellants and the conservation of hardware being a very important economic indicator for favor. But ultimately do and don't do matter as well.

I think I will leave it at this point. I have notions which may be quite questionable. I would rather think it over a bit more.

Done.

Last edited by Void (2019-03-22 11:36:07)

GW Johnson · 2019-03-22 12:16:42

During the very late 1950's into the early 1960's, midair recovery of reentering spy satellites was done by the US. I think these were the "Pioneer" series, but memory fails after so much time.

These satellites shed heat shields, popped chutes, and were snagged in midair by C-130's equipped with a sort of "fork" to catch the chute shroud lines. This wasn't as reliable as they wanted, so it was abandoned.

Some things just do not scale to very much larger sizes, and chutes are one of them. Without the chute, there is not time to achieve an intercept of a supersonic free-falling object. At, say, 2000 ft/sec, it takes only 20 seconds to hit the surface, from 40,000 feet. That's not a practical intercept timeline, even if 3 times longer.

For lower stages, there are lifting winged landings, chutes to splashdown, and retro-propulsive landings. Entry heating is just not that severe, compared to reentering upper stages.

Lifting wings are heavy, and too draggy on ascent. That 1950's concept proved to be not very practical.

Big items cannot be chute recovered, because chutes just do not scale up to large sizes in any practical sense. Plus, sea recovery is expensive, because of the ships and the labor. The shuttle proved that with its boosters. That 1960's concept has thus also proven impractical.

That leaves supersonic retro-propulsive landings. Spacex and to some extent Blue Origin, have proven this concept quite practical, most especially if you can recover at the launch site (avoiding the expense of ocean recovery ships and labor).

For upper stages, there is heat shield plus chutes plus ocean recovery, and there is making the upper stage into a self-recovering spacecraft instead of an otherwise-expendable stage. The reentry heating is way-more-severe than with lower stages. Heat shield are required, end-of-issue. Period.

All the experience with lower stages says chutes and ocean recovery will be expensive. Scaling chutes to very large sizes we already know to be infeasible. Which leaves you with the spacecraft-as-second stage concept. This could be winged, as in space shuttle, X-37B, and Dreamchaser. Or it could be retro-propulsive, and wingless.

Wings are heavy and draggy-on-ascent, as we already know. The wingless retro-propulsive concept is under development as BFS/Starship by Spacex.

It will either work, or it won't. If it does, it will be impossible to beat the price by any other method. We'll see, soon enough.

GW

Last edited by GW Johnson (2019-03-22 12:24:18)

kbd512 · 2019-03-22 13:12:25

GW,

What's your take on that Russian fly-back booster concept?

Why couldn't the swivel wing concept reduce drag acceptably on ascent?

It was called Baikal, I think.

SpaceNut · 2019-03-23 09:04:14

Second time posting to topics....
The flyback booster, liquid booster, recycling recovery and such ahve been discussed in 100's of topics when doing a search for them. They are based in part with shuttle being upgraded and its eventual dimise.
Flyback search

The Lockheed's first-stage flyback booster is just one of the topics.

Using the simple Lean principles it makes sense to rever as much as you can at any point in a mission but each will come with its own penalty.
1. First stage comes with a launch of a rocket that can only use 3/4 of the fuel loading.
2. Second stage requires a reuseable heatshielding and fuel for the landing
3. Third stage would even be more complex than a second stage due to its much long use before coming back home.
4. Recycling of parts once in orbit or on a journey cycle requires refuelling and resupply for its reuse which should mean a redesign of the rocket to maximize those deliveries and not using the current rocket.
5. before we can recover insitu processes must be capable for landers moon or mars means ability to restage back in orbits for reuse, resupply and refueling not only on orbit but on the surface as well. All of which might mean a disposable lander first for setting up shop but after that we can move forward with reuse.

GW Johnson · 2019-03-23 09:58:46

Kbd512:

I looked at Baikal. It's an interesting concept. If you do two of those swivel wings to make a biplane, you can reduce landing speed to more reasonable values.

However, this thing is a supersonic missile-like booster. Its stage-off speed is mildly supersonic in the Mach 2 to 3 range. That far from the well-hypersonic Mach 10-ish staging speed of a launch vehicle.

There's reason to doubt straight wings would be feasible at such speeds.

GW

Last edited by GW Johnson (2019-03-23 09:59:16)

kbd512 · 2019-03-23 14:23:53

GW,

Are you familiar with ring-shaped airfoils?

Suppose we had 3 to 5 ring airfoils located at different stations along the body of the booster and used adaptive compliant control surface technology to actuate sections of the airfoils for directional control. That should greatly limit the aerodynamic loads that would otherwise be placed upon a long slender wing. While the booster is on its way up, the airfoils would be tucked tightly against the body of the booster and then deployed on the way down using the "Iris" adaptive compliant surface technology. The nose of the booster would contain a small gas turbine consuming residual gaseous propellant and take advantage of the Coanda effect to provide propulsion and extra lift during the landing sequence. The landing gear would be multiple fixed skid plates mounted to the ring airfoils. We'd use reverse thrust from the gas turbine to help bring the vehicle to a halt after landing.

FlexSys - Aero - Improving Aerodynamics

FlexSys - Mechanisms - Jointless Iris

Edit: On second thought, we could just use the exhaust from a small thruster or thrusters using gaseous propellant that's mounted in the nose and then use the rocket exhaust to provide lift.

Last edited by kbd512 (2019-03-23 14:30:54)

GW Johnson · 2019-03-24 12:48:55

I flew lots of ring-shaped paper airplanes as an undergrad engineer. The same basic principle works supersonically (with draggy complications) as the grid fins Spacex stole from the Russians, who used them on their (NATO codename) Adder missile (also known in the west as "AMRAAMski").

What you have to face regarding flyback launch boosters is speed at entry to the atmosphere, in the same ballpark as staging speed. Unless you fire lots of rocket impulse to slow down the way Spacex does, you will be hitting air at about Mach 10-ish, some 3-3.5 km/s speeds.

That's definitely hypersonic, meaning convective heating will be quite large. So will the air loads, unless you positively control to an end-on attitude. That speed also rules out exposed aluminum tankage; the air recovery temperatures are just too high. Thin tank walls cannot heat sink very well at all.

Carbon-epoxy structures take even less soakout temperature than aluminum. There are NO lightweight solutions to run that hot. (And titanium is NOT a high-temperature material, contrary to popular belief.)

At those speeds, you need no wings to generate lift, even a cylinder has enough body lift to fly quite well and at rather low angles of attack. ASALM-PTV was wingless, cylindrical, and flew quite well on body lift alone, from Mach 2.5 to Mach 4. Flying weight divided by planform (diameter times length) was only about 50 psf max. That's a rather modest wing loading for a high-supersonic vehicle.

Where you start needing wings is from around Mach 1 on down. Subsonic is where you want to deploy your swivel wings or iris-ing ring wings. Practical landing speeds are 200 KIAS or slower. Fortunately, if your propellant is expended, your wing loading can possibly be low enough to support a decent landing speed.

But you ain't gonna do this at an expendable stage's 5% inert mass fraction. The wings and the landing gear weigh something. And you may or may not need a bit of heat shield on one end to get through that entry. I suspect the inert mass fraction will be in the 10-12% range. Maybe more, for a less talented design team.

GW

Last edited by GW Johnson (2019-03-24 12:57:42)

kbd512 · 2019-03-24 14:28:01

GW,

I don't want to use rigid carbon fiber composite structures for this application. I want to use soft woven CarbonX fabric structures inflated with high pressure gas like CO2 or N2 that can be deformed or deflected using cables for directional control or added lift. The fabric in question is approximately 8oz per square yard.

DLR - Aerothermal Analysis of Re-usable First Stage during Rocket Retro-propulsion

CarbonX - Science / Innovation

GW Johnson · 2019-03-25 16:56:01

Kbd512:

Reentry-capable inflatables are a bit outside what I know much about. However, carbon fiber cloth is like fiberglass cloth: porous, not gas-tight at all. Not even close to gas-tight. You'll inherently be using some sort of multi-layer structure to do this.

The carbon cloth can take reentry heat to a point, and you can put "something" (I dunno what) inside it as a layer of insulation (and I dunno how thick), with an inner layer of "something else" that is gas-tight. That something else is likely some sort of polymer film. Those are gone by somewhere in the 200-300 F range, excepting teflon, which can go to 600 F-ish.

Your inflation pressure is going to be substantial. You need an inflation pressure that exceeds the shocked stagnation pressure of the oncoming stream. Otherwise, the wind pressure will dent, or even collapse, your inflated item.

GW

SpaceNut · 2019-03-25 17:02:46

Look at the ballute and hypercone topics for an inflateable design info that we may have in searching for an answer.

Looking at the mars airplane the wings were epoxy sprayed in when inflating and then uv cure to hold structure which as temperature inside the ring would rise could be vented.

kbd512 · 2019-03-25 17:22:40

GW,

One of the thermal-mechanical properties of CarbonX is that heating up the fabric causes it to swell to prevent oxidation of the material. It's part of how it works to prevent combustion. It's on their website or in one of their videos I watched on YouTube where they show what the fabric does when you take a blowtorch to it. It's certainly not gas tight in the sense that it would hold the extreme pressure required for deployment and maintaining rigidity. That would definitely have to be done with some kind of para aramid reinforced tubing. Even so, what I envisioned was some kind of multiple semi-circular grid fin / airfoil system that's tightly wrapped around the rocket during launch and then deployed after sufficient speed has been bled off during a ballistic reentry flight path. The idea would be to glide to a runway and then slide down the runway on skid pads. It's a partially expendable recovery system, but it could be significantly lighter than the fuel required for vertical landing and CarbonX fabric is cheap, which could mean a greater portion of the booster's overall performance increment is retained to deliver useful payload. Even if it rolls onto its side during landing, it's connected to multiple highly pressurized circumferential donuts to protect the rocket from contact with the ground.

Did I mention that the materials are very cheap and the booster is less prone to tipping over?

I just thought it'd be an interesting experiment to try. If it doesn't work, then we can cross it off the list of potential ways to improve the performance of a reusable booster stage that don't work. If it does work, then we have a very low cost way to recover boosters that doesn't hurt performance too much that also improves gliding cross-range for recovery.

GW Johnson · 2019-03-31 16:51:33

Kbd512:

Your reference to the pivot-wing "Baikal" booster rocket stage got me thinking. I had looked at a folding-wing spaceplane that could enter dead-broadside without ripping its wings off (looking very much like a folding-wing carrier fighter from WW2, actually).

The pivot-wing approach is limited in how much wing it provides if only dorsally mounted, but would be much easier to implement as a heat-protected entry design, than my hinged folding wing.

I've been looking closely at it, and I like the results I get. Pivot wing, folding butterfly V-tail, 2 pilots, 5 metric tons of cargo. Vehicle is about 17-18 meters long, masses 28.5 metric tons. I think it might fit a Falcon Heavy to launch. 2.4 km/s delta-vee capability while in space, making a whole slew of missions feasible, on MMH-NTO storable and hypergolic propellants (same propellants for main engine and attitude thrusters).

Re-enters dead broadside with wing stowed, and tails folded, decelerates aerodynamically still dead-broadside to just above Mach 1, then unfolds tails to pitch streamwise and pop a drogue of the same drag as dead-broadside vehicle (subsonic dead-broadside terminal speeds at 60 kft and 20 kft).

Once subsonic streamwise on the drogue, swivel-out the wing and cut the drogue. Pull out of the dive and glide to the landing as a straight-wing, V-tail glider. Wing can be a subsonic airfoil for good approach and landing characteristics.

Dry lake bed landing on an X-15 type gear set: steerable nosewheel and two aft steel skids. Stow the wing and roll it into a C-130, to fly back to any convenient launch site.

The ballistic coefficient is low enough, and the belly flat enough, to have the stagnation point reradiate effectively the entry convective heating, at 0.80 emissivity, and surface temperature 2340 F, cool enough for alumino-silicate low-density ceramics, and no carbon-carbon anything. It doesn't have to be shuttle tile, I once made a fabric-reinforced material that was almost as good thermally, and tougher structurally, than NASA's, plus the fabric offers a redundant retention means that NASA utterly lacked.

Peaks at 6.2 gees, with only 30-40 seconds at gees above 5, during entry. This is entirely feasible for a seated pilot to take "eyeballs-down". Not a gentle ride, but not so very rough, either.

If landing with full cargo aboard, sea level landing speed at stall is about 215 mph, lower if you land at a lighter weight. Similar to X-15, actually.

I think it's a very promising idea. Once I get this "saucered and blowed", it'll show up on my "exrocketman" site. I have you to thank for the inspiration. Many thanks!

GW

Last edited by GW Johnson (2019-03-31 16:55:04)

kbd512 · 2019-04-03 14:10:55

GW,

Given that the internal fuel and payload mass arrangement and wing are already positioned such that it's over what is ostensibly a fairly consistent CG position, then in the interest of lowering the aero loads imposed by the butterfly tail structure and to generate a more axis-symmetric loading of the fuselage structure during control surface deflection, is there any reason why we couldn't employ a set of 4 grid fins on the upper fuselage, 2 near the nose and 2 on the tail?

If nothing else, maybe we could get rid of some more heat shielding mass and reduce drag further during launch by keeping the grid fins stowed. Maybe we could also negate the requirement for a parachute system and just use the grid fins and fuselage to bleed off airspeed. What altitude do you think the vehicle would be subsonic at using the 4 post grid fin arrangement, assuming we could continue to use the lift generated by the fuselage at lower altitude without over-stressing the vehicle?

GW Johnson · 2019-04-04 09:02:15

Kbd512:

It's kinda hard to answer your specific questions, since all I did was a bare-bones feasibility study.

I did check dead-broadside terminal velocity with stowed wing as Mach 0.8-ish at 60 kft, and Mach 0.3-ish at 20 kft. I thought I would use small displacements of the V-tail sort of like shuttle's body flap, to control pitch during and after entry, and unfolding more dramatically to help going streamwise, after going subsonic while dead broadside.

Seems like an anti-spin drogue chute would be cheaper, simpler, and lighter-weight than any sort of actuated grid fin arrangement. I got equivalent drag out of a chute about 8 feet diameter. It only serves to prevent going supersonic in the dive while unstowing the wing. Not much different than the anti-spin chute on the NF-104, really.

As for heat shielding, only the vehicle belly and the windward sides of the V-tail fins need it. I was going to use my cloth-reinforced low-density ceramic for that. It's about the same density as the heaviest grades of styrofoam. I would bond it to the belly in panels about a yard in dimension, but also grip the reinforcing cloth, for redundant retention.

Thin skins of stainless or inconel, coated emissive black, would be adequate to re-radiation cool, from within the wake zone of a vehicle entering dead-broadside. Only the upper surface of the wing need be made that way.

GW

Last edited by GW Johnson (2019-04-04 09:03:59)

SpaceNut · 2019-08-06 18:53:06

This could help it launch more rockets and save money. Big like in space x Falcon's or little like Rocket Lab but not Nasa or its contractors, no, no they love money too much to do so....

Rocket Lab will reuse its rockets by catching them with a helicopte

Get in the game Nasa figure it out.....

kbd512 · 2019-08-14 21:00:59

To paraphrase Dr. Zubrin, there's a difference between spending money to do something and doing something to spend money. The US government typically has the latter problem, which is why they shouldn't be so deeply involved in a now well-established commercial business. NASA should pay for competitively bid launch services, rather than being forced to design and build things for political or workfare purposes. That would free up a fat chunk of their budget to develop and build the long duration habitation vehicles required to take us to other worlds.

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#1 2019-03-21 16:03:50

Reuability Methods for Rockets:

#2 2019-03-22 05:55:30

Re: Reuability Methods for Rockets:

#3 2019-03-22 10:44:48

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#4 2019-03-22 12:16:42

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#5 2019-03-22 13:12:25

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#6 2019-03-23 09:04:14

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#7 2019-03-23 09:58:46

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#8 2019-03-23 14:23:53

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#9 2019-03-24 12:48:55

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#10 2019-03-24 14:28:01

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#11 2019-03-25 16:56:01

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#12 2019-03-25 17:02:46

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#13 2019-03-25 17:22:40

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#14 2019-03-31 16:51:33

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#15 2019-04-03 14:10:55

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#16 2019-04-04 09:02:15

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#17 2019-08-06 18:53:06

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#18 2019-08-14 21:00:59

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