tater Posted July 22, 2021 Author Share Posted July 22, 2021 Finding information on this is non-trivial, they are being quiet: "There are therefore separate tanks: high pressure for the DKS, and low pressure for the DTS and DPS. For some reason that I do not know (maybe software bug), the pressures between the tanks have been equalized, and therefore operation of the DKS is no longer possible. 3/4" No idea where this information is coming from, take with a fistful of salt. Anatoly Zak said they have "30 orbits" which presumably refers to a point at which an ISS rendezvous will no longer be possible at all. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted July 22, 2021 Share Posted July 22, 2021 (edited) 50 minutes ago, tater said: There are therefore separate tanks: high pressure for the DKS, and low pressure for the DTS and DPS Vice versa. *** 4 pairs of tanks (320 * 48 cm), 3 pair of low pressure (for the "main" engines, 2 x DKS), 1 pair of high pressure (for RCS aka DPS and DTS). (Each pair - UDMH and NTO). *** DPS ("dvigatel prichalivaniya i stabilizatsii", "engine of docking and stabilization") originally was 40 kgf, and there is 5 and more of them in every of four blocks, depending on particular module. DTS ("dvigatel tochnoy stabilizatsii", "engine of accurate/precise stabilization") originally was 1.2 kgf, and there was a battery of 8 of them in the two blocks at the ship end opposite to the active docking port. All of them are pressure-fed and are fed from the high-pressure pair of tanks. *** The "main" engines (DKS, "dvigatel korrektsii i sblizheniya", "engine of correction and approaching") are turbopump-fed and suck fuel from any of 3 low-pressure, switching a valve between them. It's open-cycle, the pump exhaust is exhausted together with the engine jet, providing the low thrust mode (originally - 47 kgf). When the engine is ignited, it's the high thrust mode (originally - 400+47 = 447 kgf). Also the DKS engine's turbopump is used as a compressor to pump the fuel from low-pressure tanks into the high-pressure pair to fill it during the multimonth flight when the TKS (from which the 77-type modules are derived) is docked to the Almaz station as an expendable propulsion-energetical-storage unit. That's exactly why such complicated scheme. The propulion system of TKS iss designed as a multimodule station propulsion system. The total of 3 800 kg of fuel is absolutely excessive for the interorbital flight, it's to keep the low-orbit Almaz on the 200 km high orbit for 3 months, constantly pushing it to compensate the air drag losses. So, one tank pair contains ~900 kg of fuel. 3500 m/s * ln(20/(20-0.9)) ~= 160 m/s of delta-V if all three other pairs are unavailable. The DKS (with lifespan of > 1000 (actually, up to 10 000) ignitions is required not so much for the ship, but for the complex in whole. "Correction" = correction of the station orbit, "approaching" = approaching of the ship to the station. They are not necessary for the ship, they are needed to push the station, and are just a bonus for the ship itself. Also, the (originally) 2x3x40 = 240 kgf DPS nozzles are enough to approach to the station and dock. The evil twin of TKS, Big Gemini, "didn't" have other engines at all. It "was" using its DPS all the flight. As well, Apollo (having a lot of common with Big G in the propulsion) needed the main engine only to save fuel on lhigh-delta-v maneuvers. *** So, if the diagnosis is correct, we can understand it like the valves through which the (main engine) DKS turbopumps compress the fuel from 3 low-pressure tank pairs into the 1 high-pressure tank pair, is broken, and due to the high pressure in system, the turbopumps of DKS can't be turbopumping. So, the two main engines (DKS) are disabled, and the module can't serve as a tug for the whole ISS. But if/as the pressure is enough high to feed the pressure-fed DPS (and DTS) RCS engines, they can go to the station by HNIJKL keys instead of AZ and dock. *** Also the DTS (the tiniest ones) are needed not for the ship, but for the precise stabilization of the station. The ship/module actually needs only DPS to be happy. Edited July 22, 2021 by kerbiloid Quote Link to comment Share on other sites More sharing options...
sh1pman Posted July 22, 2021 Share Posted July 22, 2021 26 minutes ago, kerbiloid said: So, the two main engines (DKS) are disabled, and the module can't serve as a tug for the whole ISS. No big deal, Progress can do that. Or Cygnus. Maybe Starship in the future. Quote Link to comment Share on other sites More sharing options...
DDE Posted July 22, 2021 Share Posted July 22, 2021 Quote Link to comment Share on other sites More sharing options...
tater Posted July 22, 2021 Author Share Posted July 22, 2021 It's a bad look for there to be no official word. They are communicating with NASA, obviously, but NASA is not going to report on anything. Quote Link to comment Share on other sites More sharing options...
tater Posted July 22, 2021 Author Share Posted July 22, 2021 Musta worked. Quote Link to comment Share on other sites More sharing options...
tater Posted July 22, 2021 Author Share Posted July 22, 2021 Quote Link to comment Share on other sites More sharing options...
DDE Posted July 23, 2021 Share Posted July 23, 2021 Quote Link to comment Share on other sites More sharing options...
DDE Posted July 23, 2021 Share Posted July 23, 2021 Quote Link to comment Share on other sites More sharing options...
SOXBLOX Posted July 23, 2021 Share Posted July 23, 2021 Nauka is surely one of the most troubled spacecraft ever to fly. Maybe it'll make it... Quote Link to comment Share on other sites More sharing options...
DDE Posted July 23, 2021 Share Posted July 23, 2021 I'm surprised it is a problem. If they restored FGB's fuel capacity to what it roughly was, shouldn't they be able to keep boosting it for a quite a while to seek another plane alignment? Apparently she's done two out of four planned burns (plus that unplanmed test one?) https://www.mk.ru/science/2021/07/23/otpravlennyy-k-mks-kosmicheskiy-modul-nauka-udalos-reanimirovat.html Quote Link to comment Share on other sites More sharing options...
tater Posted July 23, 2021 Author Share Posted July 23, 2021 13 minutes ago, DDE said: https://www.mk.ru/science/2021/07/23/otpravlennyy-k-mks-kosmicheskiy-modul-nauka-udalos-reanimirovat.html “We cannot allow this,” the responsible persons told us off the record. "They'll blow their heads off us!" Google translate having trouble, presumably "their" should be "our." Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted July 23, 2021 Share Posted July 23, 2021 It's "they will slash off the heads from us" Quote Link to comment Share on other sites More sharing options...
Minmus Taster Posted July 23, 2021 Share Posted July 23, 2021 Wow Nauka has just been having...a really bad time... Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted July 23, 2021 Share Posted July 23, 2021 An uncrewed space flight rarely is so intriguing. They should launch that filming crew in an escape capsule. It's a ready survival movie to the date. Quote Link to comment Share on other sites More sharing options...
DDE Posted July 23, 2021 Share Posted July 23, 2021 43 minutes ago, kerbiloid said: They should launch that filming crew in an escape capsule. It's a ready survival movie to the date. That would require a VA to go with the FGB. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted July 23, 2021 Share Posted July 23, 2021 2 minutes ago, DDE said: That would require a VA to go with the FGB. They could berth the Soyuz's capsule and habitat to the docking port overturned and put the seats in the habitat in proper direction. Or just fly in Nauka and return later, from ISS. Or ln an empty Soyuz docked to Nauka in next launch. Quote Link to comment Share on other sites More sharing options...
DDE Posted July 23, 2021 Share Posted July 23, 2021 Appropriate Krikalyov face Quote Link to comment Share on other sites More sharing options...
tater Posted July 23, 2021 Author Share Posted July 23, 2021 He also reported that they were gonna try firing the DKS 30-60 minutes ago. Quote Link to comment Share on other sites More sharing options...
tater Posted July 23, 2021 Author Share Posted July 23, 2021 I just saw some reporting that said they managed to start DKS. Fingers crossed. Quote Link to comment Share on other sites More sharing options...
DDE Posted July 23, 2021 Share Posted July 23, 2021 Quote Link to comment Share on other sites More sharing options...
DDE Posted July 23, 2021 Share Posted July 23, 2021 We interrupt this program for a brief appearance by Great Scott Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted July 24, 2021 Share Posted July 24, 2021 (edited) Btw that twitter also has a detailed DKS ("engine of correction and approaching", i,e, the "main" engine) photo. Here you can see the main nozzle (large), and the turbopump nozzle (small, to the right). When mounted, the main nozzle sticks from a plate with the "white" part, while the turbopump nozzle looks through a hole in it. *** Also , there is the grapple effector of the Aist robotic arm, the Russian equivalent of Canadarm. It covers the grapple fixture, these small rollers roll around to adjust the latch position, then the entered stick in the middle pulls. And the detailed description with pictures. https://www.kosmonavtika.com/vaisseaux/bourane/tech/sbm/sbm.html together with this http://www.buran.ru/htm/bighand.htm Edited July 24, 2021 by kerbiloid Quote Link to comment Share on other sites More sharing options...
tater Posted July 24, 2021 Author Share Posted July 24, 2021 After it is attached to ISS, will it ever use DKS again, or does it use thrusters? Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted July 24, 2021 Share Posted July 24, 2021 Just now, tater said: After it is attached to ISS, will it ever use DKS again, or does it use thrusters? Unlike the native TKS, whose DKS are pointing away from the station, the type 77 modules have them mounted on the conical base of the wide part, tilted to the axis and pointing towards the station. And the Mir orbit was being raised by Progresses. So, unlikely it can be used in any way but turbopumping the fuel into the high-pressure tanks for RCS engines (DPS and DTS). (Though it is not physically impossible). Quote Link to comment Share on other sites More sharing options...
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