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That table is incomplete. 301 stainless and 17-4 stainless are available in comparable strength/weight to AL 7075-T6, and specialty stainless steels like S53 can reach strength/weight ratios even higher: four times the strength of 7075-T6 at only 3 times the weight. Dependent on material work and thermal history, of course.
OTOH SS301  is 1/10 the thermal conductivity of Aluminum (which helped a lot with LOX boiloff when it was used for the pressure stabilized Atlas LV's).

Given the flame temperature of pretty much any propellant combination Vs Aluminum melting temp it should be impossible to mfg a thrust chamber for any rocket, except it's been done since Bell aerospace designed one to power the bomb/fuel pod on the B58 (which went on to power the Agena stage).

So I'd say a T/W ratio of 200:1 for a dual expander cycle is possible because so much of the non  core engine runs pretty cold. No GG, no hot turbines Vs the GG and hot turbine (or is it separate pump drives?) on Merlin.

Of course it's still a lot smaller.
Falcon 9 can do all Atlas V 401 launches with RTLS or low energy ASDS landings.  There are maybe 20-30 Atlas launches to go -- ever.
A single Falcon 9 Block 5 could launch most all of them.

The Starlink Constellation (if that is what it will be called) requires a hundred F9 launches per year or more.  It starts flying in 2019.  The rest of the World's launches only need to increase 10% for there to be 100s of launches per year in early-2020s.

What is 'distant' or 'fantasy' about this?


It is more than  'distant' or 'fantasy', it is inane.  Starlink Constellation launch rate is not going to happen  Block 5 is not going to be what you think.

Lets talk some reality.  A single Falcon 9 Block 5 is only one upper stage and fairing.  That is one launch, much less than 20-30.

This thread needs to be locked, it serves no purpose other than a mouthpiece for a minor Spacex sect/cult.

What do you think is likely to happen with SpaceX Starlink launches? What will SpaceX achieve with F9 Block 5?
Iran :Successfull test the Khorramshahr
Better quality footage

ULA won't switch to AFTS with Atlas and Delta. They will implement it on Vulcan. That's what has been discussed. No first hand knowledge by me.
Space Goose
But what you gonna do when if the Goose lands on you? :)
Yes, as Jim said elsewhere:

Spacex has more flown boosters than it knows what to do with them and has been breaking them apart and scrapping them.
General Discussion / Re: Skepticism about space colonization
« Last post by john smith 19 on Today at 08:58 AM »
Yes, but the greenhouses could be underground and say a long tube with grow lights.  A big long building using Martian stone built in an arch shape and covered with Martian soil for radiation protection. 

Large open spaces would probably be built after food, power, and manufacturing of habitats are done.  All probably interconnected by transportation tunnels.  Electric carts could be used to travel around inside from greenhouses for food, fish, and small animals, to living quarters, to processing of raw materials areas, etc.  Power will probably be solar initially until say small nuclear power plants could be brought.
That's the sort of answering of skeptics points that I'd like to see more of.  :)

However artificial lighting multiplies the power budget of a settlement. IIRC the power budget with normal light budget was about 5Kw/Person/day but with artificial lighting it's more like 60Kw/person/day.

Data point. The entire power generation of ISS is 200Kw, but IIRC it's in near permanent sunlight. 
ISS Section / Re: Expedition 53 Thread
« Last post by jacqmans on Today at 08:52 AM »

ISS Daily Summary Report – 9/21/2017

Posted on September 21, 2017 at 4:00 pm by HQ.

Sarcolab-3: After successfully completing three days of the ankle configuration exercises, today USOS and Russian subjects conducted the knee protocol for Sarcolab-3. The subjects ingressed the Muscle Atrophy Research & Exercise System (MARES) chair, installed the knee Electromyography (EMG) electrodes and began the knee exercise protocol, while an operator collected ultrasound images of the subject’s right leg. The data collected for Sarcolab-3 will be compared to pre and post flight measurements to assess the impact of hypothesized microgravity induced muscle loss.  Myotendinous and Neuromuscular Adaptation to Long-term Spaceflight (Sarcolab) investigates the adaptation and deterioration of the soleus (calf muscle) where it joins the Achilles tendon, which links it to the heel and carries loads from the entire body. Muscle fiber samples are taken from crewmembers before and after flight, and analyzed for changes in structural and chemical properties. MRI and ultrasound tests and electrode stimulation are conducted to help assess muscle and tendon changes caused by microgravity exposure.

Payload On-Orbit Still Shots for Utilization and Maintenance (POSSUM) Payload Photo: The crew took digital photos of all payload racks in the US Lab, JEM Pressurized Module (JPM), and Columbus module to document configuration changes.

Fine Motor Skills (FMS): A crewmember completed a FMS session which was executed on a touchscreen tablet, where the subject performs a series of interactive tasks. The investigation studies how fine motor skills are affected by long-term microgravity exposure, different phases of microgravity adaptation, and sensorimotor recovery after returning to Earth gravity. The goal of FMS is to answer how fine motor performance in microgravity trend/vary over the duration of a six-month and year-long space mission; how fine motor performance on orbit compare with that of a closely matched participant on Earth; and how performance trend/vary before and after gravitational transitions, including the periods of early flight adaptation, and very early/near immediate post-flight periods.

Tropical Cyclone Maria: The crew setup and configured camera settings, before capturing images of Hurricane Maria to support the Tropical Cyclone investigation.  The Tropical Cyclone investigation is used to capture images of tropical cyclones and hurricanes that are rated at Category 3 or greater on the Saffir-Simpson scale. A pseudo-stereoscopic method is used to determine the altitudes of the cloud tops near the center (eye) of a cyclone by precisely tracking the apparent positions of cloud features with respect to the Earth and how those positions change over time as an observer (the ISS in this case) passes over the storm. The photographic images will be used to demonstrate that pseudo-spectroscopy can be used to measure the cloud altitudes to sufficient precision so that, when combined with other remote-sensing data, an accurate determination of the intensity of hurricane or cyclone can be made.

Marrow:  Today a 51S crewmember completed breath and ambient air sample collections for the Marrow investigation, which looks at the effect of microgravity on bone marrow. It is believed that microgravity, like long-duration bed rest on Earth, has a negative effect on the bone marrow and the blood cells that are produced in the bone marrow.

Rodent Research 9 (RR-9):  Today the crew completed an audit of the Rodent Research -9 hardware and supplies. The RR-9 investigation was successfully completed and returned on SpaceX-12 last week. The RR-9 experiment studies how microgravity affects the immune systems, muscles and bones of rodents during extended stays aboard the ISS.  After approximately 30 days aboard the ISS, the mice will be returned to Earth where scientists on the ground will study how their time in space has affected various tissues, including brain, muscle, heart, joint, the eyes and the immune system.

Multi-Omics-Mouse Closeout The crew performed Multi-Omics closeout activities by removing the Mouse Habitat Units from the Cell Biology Experiment Facility (CBEF), cleaning and taking photos of the glove box, and reconfiguring the video cables between the Video Compression and Recording Unit 2 (VRU2) and the CBEF.

Manufacturing Device (MD) Operations: The crew removed and replaced the MD feedstock canister, extruder, and print tray. The Manufacturing Device – Additive Manufacturing Facility (AMF) enables the production of components on the ISS for both NASA and commercial objectives. Parts, entire experiments, and tools can be created on demand utilizing the AMF that is installed into an Express Rack locker location. The AMF is capable of producing parts out of a wide variety of thermopolymers including engineered plastics.

N3 Aft Port Intermodule Ventilation (IMV) Fan Inlet Cleaning: The crew cleaned this location to remove Foreign Object Debris (FOD) from IMV fan inlets and silencers.

Simplified Aid for EVA Rescue (SAFER) Training: In preparation for the upcoming EVAs in October, two US crewmembers were scheduled to perform virtual reality (VR) training simulating emergency recovery using SAFER. In the event a crew member becomes untethered while conducting an EVA, SAFER can be used to safely maneuver for recovery.  During the first session, there were some configuration issues, but once the configuration issues were resolved there were still some issues with executing the session.  Both of today’s sessions were deferred until the ground specialists can further review.

Advance Resistive Exercise Device (ARED) Upper Rack Cable Kinked: Today, the crew reported a reoccurrence of the ARED Upper Rack cable kinking.  No cable damage was reported.  The crew straightened the cable and took imagery for ground review. This is the second instance of this cable kinking this week.  There are spare cables on-orbit.
AFTS is probably the only way USAF will get to 48 launches... that and having a launch provider that brings that many payloads to the US launch facilities.  Both AFTS and reusable launches are about cost of launch services... without SpaceX pushing the system incredibly hard, neither of these 'features' would be a part of the USAF's 'problem' because US launchers are otherwise too expensive for anything but USG launches (7-10 per year that are not SpaceX).
I think AFTS is necessary, but not a sufficient feature to get to 48 launches a year.

When I asked, on another thread, if it would be possible to launch all major US launch vehicles (IE Antares, Atlas V, DIV, F9 at the time) in a "salvo" off of different pads within a single week (different pads, so no pad refurb time) Jim posted that it wouldn't and the long pole in the tent was testing the (large) number of voice channels between the different range sites.

Which also begs the question is AFTS now SOP for all LVs on the range?
If not who still needs the manual system, which it's been stated needs the involvement of 98 staff to operate? And when do they plan (or do they plan) to transition to AFTS?

AFTS should be the baseline for new LV's (presumably Vulcan will have it) on US ranges but other LV's predate it and I'm not sure if it's viewed as a nice-to-have or a must-move-to.
There will be a Soyuz-2 launch from Plesetsk on 25th October 2017. No more information.
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