New Russian People-Carrier to Land on Solids?

[Proponent]

The BBC reports that RKK Energia's new six-person spacecraft will "rely exclusively on solid-propellant engines for landing."

Is this for real?  Braking for landing is a low-impulse, high-thrust maneuver.  Therefore it could be that in a purely theoretical sense advantages of solid propellants' high density and high thrust-to-weight ratio outweighs the disadvantages of their low specific impulse.  But this just seems weird.

Are the solids used for launch escape too?  I would guess that for escape all motors would fire simultaneously but for landing they would be used in salvos to keep the G-forces down.

Might there be liquid-propellant verniers for fine adjustment of thrust, or is all of the throttling done with the solids themselves?

[Space Invaders]

If the reentry system as a whole is sound enough to withstand a ballistic reentry, it doesn't seem that weird. The terminal velocity just above sea-level for an Apollo-type capsule would be in the vicinity of 375 km/h (104.66 m/s). A high g load need not be applied to slow the craft to a soft landing speed. Firing the solid rockets for the last 6-8 seconds at about 3 g should do the trick.

If, like the Apollo CM, the Russian capsule can generate a non-negligible amount of lift (0.368 L/D ratio for the CM), then it will be even simpler.

[Nickolai]

The reason they decided to use solids has to do with landing precision requirements. The capsule is required to land on Russian territory, and my guess is that the landing sites are more like fields in a forest as opposed to steppes like Kazakhstan. A parachute landing would be blown around by the wind too much, reducing landing precision.

[Proponent]

If the reentry system as a whole is sound enough to withstand a ballistic reentry, it doesn't seem that weird. The terminal velocity just above sea-level for an Apollo-type capsule would be in the vicinity of 375 km/h (104.66 m/s). A high g load need not be applied to slow the craft to a soft landing speed. Firing the solid rockets for the last 6-8 seconds at about 3 g should do the trick.

I agree--that's what I meant by "low-impulse, high-thrust maneuver."  What's weird about it is that if the landing is to be solely on rocket power, then fine control of the thrust will be needed to effect touch-down at a low sink rate and negligible horizontal speed.

BTW I would guess that the burn is going to last a little longer than 6-8 seconds, otherwise there's just not much time to deploy the parachute if the solids don't ignite.

If, like the Apollo CM, the Russian capsule can generate a non-negligible amount of lift (0.368 L/D ratio for the CM), then it will be even simpler.

A sizeable L/D will certainly help the capsule maneuver toward its target, but I don't see how it's going to help with the landing itself unless the capsule is equipped to make make a horizontal rather than vertical landing.  And for a horizontal landing, L/D of 0.4-ish is pretty lousy.

[Proponent]

The reason they decided to use solids has to do with landing precision requirements.

It makes sense that a rocket landing would give a higher precision than a parachute one.  But still what I find weird is the use of solids.

[Space Invaders]

Perhaps because hydrazine and similar hypergolics are too toxic to be used in the lower kilometres of the atmosphere. That's been a concern with the Proton rockets because of the potential for an accident, and Russia has always had to pay for the clean-up of Proton pollution.

Also, they might be more reluctant to pollute Russian territory than Kazakh steppe.

A sizeable L/D will certainly help the capsule maneuver toward its target, but I don't see how it's going to help with the landing itself unless the capsule is equipped to make make a horizontal rather than vertical landing.  And for a horizontal landing, L/D of 0.4-ish is pretty lousy.

Not for the landing, but because it can generate some lift, it can use that to slow down somewhat. More or less like a glider falling slower than a stone, but on a much smaller scale.

[hop]

Perhaps because hydrazine and similar hypergolics are too toxic to be used in the lower kilometres of the atmosphere.

It would certainly complicate recovery operations.

Soyuz uses H202 for descent module attitude control. H202/hydrocarbon would be an obvious option where simplicity and reliable starting are required. Solids seem an odd choice, but I'm sure it can be done.

Not for the landing, but because it can generate some lift, it can use that to slow down somewhat. More or less like a glider falling slower than a stone, but on a much smaller scale.

A glider *falling* would just be a product of the ballistic coefficient. For *lift* to slow your descent rate, you have to have horizontal velocity. That doesn't help if your final landing is vertical under rocket power: The rocket would have to overcome both the vertical and horizontal components.

[zaitcev]

The reason they decided to use solids has to do with landing precision requirements.

It makes sense that a rocket landing would give a higher precision than a parachute one.  But still what I find weird is the use of solids.

This design baseline exists for more than a year and it was leaked ahead of the unveiling of Preliminary Design. Apparently the choice of solids has to do with their reliablility. The decision was made before the back-up parachute was added, and the pictures a pancaking cosmonauts weighted heavily on the minds. Personally, I think it was irrational even back then, and moreso now when a chute is available worst comes to worst. But there you have it. BTW, you can see the solids in some cutouts from last year's MAKS show. They have spherical shapes (does anyone know if a solid motor can be a sphere, and if yes, why) but you can tell they are not spherical tanks because each has a nozzle. It's rumored that having 14 of them is planned (althogh it's an old information).
-- Pete

{Edit: Forgot about the original question of abort system. No, they are not unified. Actually that BBC article has the picture which shows some of the escape tower, and Mr. Zak's own website has a picture with a better perspective.

See also http://www.russianspaceweb.com/ppts_landing.html
}

[Proponent]

Thanks much for the info; Mr. Zak's page is very informative.

BTW, you can see the solids in some cutouts from last year's MAKS show. They have spherical shapes (does anyone know if a solid motor can be a sphere, and if yes, why)

The Surveyor lunar landers of the 1960s had spherical solid retrorockets.  I think the most interesting question is what the initial shape of the propellant grain is.  If it's a hollow sphere, then thrust will increase rapidly with time as the burning area grows.  If it's a sphere with a cylindrical void, the you'd get something closer to constant thrust (which seems likely what's desired).

It's also indicated that the solids are ignited at an altitude of between 600 and 800 m.  If they fail to ignite, is there really enough time to separate the crew module from the propulsion module and open the parachute?

One question Mr. Zak's page answers is how the solids would be throttled.  I'd assumed it would be by literally throttling the nozzle (changing the throat size--a technique explored in the US a very long time ago), but now I see the motors won't actually be throttled, they'll be gimbaled to alter the vertical component of thrust.

[Danderman]

Its unlikely that solids could provide fine enough propulsion to overcome the uncertainty of the altitude and velocity of initial deployment of the system. In other words, if it turns out that the solids had a nominal deployment at 800 meters altitude and 100 meters per second velocity, but instead were delayed and fired at 600 meters and 110 meters per second, the vehicle might have a bad day if the landing system could not somehow be throttled up.

[zaitcev]

Does anyone know where this drawing comes from? I found it at a blogger.com URL, but it's hashed and does not reveal the blog post to which it was attached originally.

The question is, if the drawing is a legitimate leak or a product of enthusiast's fantasy. Its general outline looks similar to what I saw previously, but that tells us nothing.

BTW, the landing engines look like 2 hemispheric ends connected by a cylindrical section (is there an English word for such oblong shape?).

-- Pete

[fregate]

First information had been leaked by Energia poster in Farnborough Airshow back in June 2008 and published in flightglobal site blog Hyperbola by Rob Coppinger.

The schematic drawing above came from Russian Novosti Kosmonavtiki Magazine (Number 9 of 2008) and later from their web forum - if you would like to go through 600+ pages of quite heated discussion this is a link PTK NP is a Manned Transportation Vehicle of the New Generation: PTK NP
BBC article with Anatoly Zak illustrations Manned spaceship design unveiled

[Patchouli]

Looking at this crazy landing system maybe they should switch back to a winged vehicle.

Kliper's method of recovery seems a lot safer then this system.

If they want precision landing a space plane is a proven system for delivering such.
Nearly all the shuttle's safety issues were due to how it sits on the stack and not it being an aircraft.

[fregate]

...does anyone know if a solid motor can be a sphere, and if yes, why...

Pete, please have a look at solid motor engines by Thiokol Star 17 and Star 17A - they have specs that would make them suitable for Energia powered landing design, and BTW originally RCS Energia planned to use 12 solids, not 14. How come did you miss that on NK Forum, it's still a MYSTERY for me.

[Sparky]

Its unlikely that solids could provide fine enough propulsion to overcome the uncertainty of the altitude and velocity of initial deployment of the system. In other words, if it turns out that the solids had a nominal deployment at 800 meters altitude and 100 meters per second velocity, but instead were delayed and fired at 600 meters and 110 meters per second, the vehicle might have a bad day if the landing system could not somehow be throttled up.

Just a thought, nothing more:
Hypothetically, could a set of solids be "throttled" back by vectoring/gimbaling the motors away from the perpendicular? Could it also be possible to control the shape of the nozzle to control the thrust?

[Lars_J]

This article on the RSC Energia homepage has a recent interview with president/chief designer (?) Vitaly Lopota about the new spacecraft development, to follow up on Soyuz (in russian): http://www.energia.ru/ru/news/news-2010/public_09-28.html

Here is a "Google translate" english translation (I hope the URL works):
http://translate.google.com/translate?js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&sl=ru&tl=en&u=http://www.energia.ru/ru/news/news-2010/public_09-28.html&act=url

A quote regarding schedule:

"RG: When the new ship may appear in the metal?

Lopota: If you will be allocated the necessary budget, the flight tests will begin in 2015. First flight - in an unmanned version."

RG: So, the flight tests will approach Russia in five years. It is the world standard?

Lopota:[/b] This is the planned dates. They are defined as willingness to cooperation between enterprises and funding.

RG: With the shape the ship is complete clarity?

Lopota: Ships - yes. Reentry vehicle - yes. And then it all depends on the specific tasks and specific missions. Provision and targeted modification of ships."

So they are hoping for a 2015 unmanned test flight. I'm not sure about what launch vehicle would be used, though. The 'Rus' rocket - which is the ideal choice, AFAIK -  seems to be behind even Angara in development. Schematics with the craft attached to the Zenit LV have been circulating, but who knows if they are recent or not.

[patchfree]

This article on the RSC Energia homepage has a recent interview with president/chief designer (?) Vitaly Lopota about the new spacecraft development, to follow up on Soyuz (in russian): http://www.energia.ru/ru/news/news-2010/public_09-28.html

Here is a "Google translate" english translation (I hope the URL works):
http://translate.google.com/translate?js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&sl=ru&tl=en&u=http://www.energia.ru/ru/news/news-2010/public_09-28.html&act=url

A quote regarding schedule:

"RG: When the new ship may appear in the metal?

Lopota: If you will be allocated the necessary budget, the flight tests will begin in 2015. First flight - in an unmanned version."

RG: So, the flight tests will approach Russia in five years. It is the world standard?

Lopota:[/b] This is the planned dates. They are defined as willingness to cooperation between enterprises and funding.

RG: With the shape the ship is complete clarity?

Lopota: Ships - yes. Reentry vehicle - yes. And then it all depends on the specific tasks and specific missions. Provision and targeted modification of ships."

So they are hoping for a 2015 unmanned test flight. I'm not sure about what launch vehicle would be used, though. The 'Rus' rocket - which is the ideal choice, AFAIK -  seems to be behind even Angara in development. Schematics with the craft attached to the Zenit LV have been circulating, but who knows if they are recent or not.

Yes, Perminov said recently that the new ship could be, if necessary, tested from Baïkonour. That is only possible on a zenit derived rocket.

[fregate]

PTK NP landing, there is a new development in RCS Energia:
After August announcement about combined parachute-propulsive landing system (Powered landing on solid rocket motors as a main system of landing of DM and parachute/DMP backup landing system)
Muli-canopy parachute system had been mentioned (with 3 canopies) 

Note: PTK NP Descent module (VA) consist of
- Command Module (KO)
- Service Module (AO).
In case of landing on backup system Service Module would be jettisoned and only Command Module (mass ~4500kg) would be landed with Soft Landing Solid Motors (DMP) - like Soyuz DM (SA) does.
In October it was a comment by V.Lopota that main landing system would use parachutes as well as propulsive landing.