Lots of Soviet Union SLBM ignite pumpfed liquid engines underwater, with no problem.
Getting out of water is harder, with large dynamic forces disturbing GNC. Modern GNC software may solve it easier, north Korea have SLBM now.
More problem occurs on reliability, assembling/testing/debugging, scrub after filling propellants, etc.
Generally, SLBM are neither cheaper nor easier than land based ICBM counterparts. Even silo based / TEL vehicle based ICBM tend to begin with launch pad during development.
Better to start the BDB concept on launchpad first and move to sea later, instead of combining two risky attempt together.
Without launchpad, the vehicle have to integrate certain functions of launchpad inside, and assembling / tesing on launchpad becomes impossible.
Quote from: groundbound on 09/06/2017 06:11 pm9.2 kps LEO speed also seems unusual.That's actually explainable. 9200 m/s is a rule of thumb orbital speed for LO2/LH2 rockets including all losses, which are usually expected to be a bit higher with LO2/LH2, in the same way old rocket engineering books list 30kfps (9144m/s) as the round number to achieve orbit. What's rare is quoting it as it's a placeholder. Smart rocket developers optimize their trajectories to reduce losses because every m/s you can reduce them by means you can either deliver the payload with a smaller rocket or a bigger payload.
9.2 kps LEO speed also seems unusual.
Also, I am not sure why they have a different altitude listed for "equatorial" is that supposed to represent the performance boost if it launched from the equator?
“I think it’s a function of time,” Bruno said. “Initially, they will begin and they will try and service the small satellite launch market. But as that becomes a real market, that attracts the rest of us. I think the real economics will favor rideshares as a solution so then it flips to the other side.”
Wow, who would have thought ?http://spacenews.com/big-launch-companies-predict-doom-for-upcoming-smallsat-launchers/Quote“I think it’s a function of time,” Bruno said. “Initially, they will begin and they will try and service the small satellite launch market. But as that becomes a real market, that attracts the rest of us. I think the real economics will favor rideshares as a solution so then it flips to the other side.”Notably absent from the panel were anyone trying to build a smallsat launcher, Shotwell's Falcon 1 saga notwithstanding
A dedicated small LV means smallsat gets delivered direct to its target orbit so doesn't need any extra DV. In case of rideshare typically main payload will not be going to smallsats target orbit. So additional DV will be required.Option 1) Use 2t US to deliver 50kg smallsat to target orbit after main mission. Not very efficient use of expensive US.
2) Use space tug eg Spacefight Services Sherpa. More efficient but definitely not free.
3) Add extra propulsion to smallsat which adds costs. Launch by small LV is now an expensive option as smallsat is heavier and more expensive.
Rideshare reduces launch opportunities, look at delays with Spaceflight Services dedicated F9 launch.
While initially ELV, small LV companies will most likely move to reuseable LVs to be more responsive and lower launch costs. They may start to grow and threaten lower end of main stream launch market.
Quote from: TrevorMonty on 09/16/2017 10:02 amA dedicated small LV means smallsat gets delivered direct to its target orbit so doesn't need any extra DV. In case of rideshare typically main payload will not be going to smallsats target orbit. So additional DV will be required.Option 1) Use 2t US to deliver 50kg smallsat to target orbit after main mission. Not very efficient use of expensive US. In an ELV it will be expended anyway. Quote from: TrevorMonty2) Use space tug eg Spacefight Services Sherpa. More efficient but definitely not free. Is anyone proposing to launch payloads on a smallsat LV for free?Quote from: TrevorMonty3) Add extra propulsion to smallsat which adds costs. Launch by small LV is now an expensive option as smallsat is heavier and more expensive.Depends on mission.Quote from: TrevorMontyRideshare reduces launch opportunities, look at delays with Spaceflight Services dedicated F9 launch. That's an interesting one. Some say Ariane 5's problem is that it could launch 2 max size comm sats that was fairly easy to schedule. Now they've grown it's 1 full size and 1 medium size. IOW A5 would be fine if the people doing the developing had upgraded it's payload at the right time.OTOH FH is expected to be all ride share for comm sats. So how many will need to get together to do that?Can the US deliver the necessary delta V to spread them out across the sky?Quote from: TrevorMontyWhile initially ELV, small LV companies will most likely move to reuseable LVs to be more responsive and lower launch costs. They may start to grow and threaten lower end of main stream launch market.Do you have any references for that? If you're thinking of SX they "moved" to a (semi) reusable LV by ending production of their small LV and moving to a much bigger one. Doing it on an F1 would mean needing to throttle down 90-95% on landing. There are valves rated at 99:1 throttling, but the pressure loss through the injectors is a major PITA.
Australian company Equatorial Launch Australia is looking to set up a launch site in the Northern Territory. They already have a US$10,000 contract from NASA (I believe this is for launching suborbital payloads). The launch site is to be called the "Arnhem Space Centre".https://www.northernstar.com.au/news/235m-plan-launch-space-industry-nt/3203973/
https://www.facebook.com/equatoriallaunchaustralia/
Apart from funding, two key issues for ELA involve security of land tenure and the demand for service.
NASA and the Defence Department appear likely clients, although a number of private companies including SpaceX, Rocket Lab, Virgin Galactic and Vector Space could also create demand.
The site provides a commercial advantage, given the proposed facilities would be 12 degrees from the equator.The proximity to the equator lowers the launch costs by up to 50 per cent.
The suborbital market is said to be worth US$2 billion and is concentrated in the US.
Re: Space Ops Australia
....It does pretty much rule out polar orbits, which is a big part of any orbital launch market.
Is it possible that these people are sincere in believing that they will be a successful and competitive launch provider?
Quote from: Comga on 09/19/2017 04:17 amRe: Space Ops Australia I think you mean ELA - not SOA..
You are correct.So many of these popping up. Steven has his work cut out just posting links to them all.
“I believe we’ve lost five launches in two years,” Barna said of the company’s overall efforts to launch its cubesat constellation. “We’ve been bumped to other launches just as many times because of failures or delays, or just because the primary customer asked. If you haven’t consciously built an entire infrastructure around the flexibility to move launches, absorb delays and cancellations, and even adapt to geopolitical and regulatory challenges, then you just aren’t prepared to launch a satellite constellation.”
Quite possible.. with Rio Tinto pulling out it seems the locals are keen for something (anything!) to happen and hence are right behind the proposal - plus they have a $10,000 grant from NASA, right?
EDIT: What I find extraordinary is an apparent (to me anyways) sudden upsurge in interest in commercial launch from down under. Is the government, dormant for so long, finally waking up? Or is it just because IAC2017 is on next week in Adelaide?
In other news, for those touting rideshare as solution to all smallsat launch needshttp://spacenews.com/minotaur-4s-canceled-commercial-cubesat-rideshares-could-spark-policy-changes/Quote“I believe we’ve lost five launches in two years,” Barna said of the company’s overall efforts to launch its cubesat constellation. “We’ve been bumped to other launches just as many times because of failures or delays, or just because the primary customer asked. If you haven’t consciously built an entire infrastructure around the flexibility to move launches, absorb delays and cancellations, and even adapt to geopolitical and regulatory challenges, then you just aren’t prepared to launch a satellite constellation.”
Quote from: savuporo on 09/14/2017 06:12 pmWow, who would have thought ?http://spacenews.com/big-launch-companies-predict-doom-for-upcoming-smallsat-launchers/Quote“I think it’s a function of time,” Bruno said. “Initially, they will begin and they will try and service the small satellite launch market. But as that becomes a real market, that attracts the rest of us. I think the real economics will favor rideshares as a solution so then it flips to the other side.”Notably absent from the panel were anyone trying to build a smallsat launcher, Shotwell's Falcon 1 saga notwithstandingA dedicated small LV means smallsat gets delivered direct to its target orbit so doesn't need any extra DV. In case of rideshare typically main payload will not be going to smallsats target orbit. So additional DV will be required.Option 1) Use 2t US to deliver 50kg smallsat to target orbit after main mission. Not very efficient use of expensive US. 2) Use space tug eg Spacefight Services Sherpa. More efficient but definitely not free.3) Add extra propulsion to smallsat which adds costs. Launch by small LV is now an expensive option as smallsat is heavier and more expensive.Rideshare reduces launch opportunities, look at delays with Spaceflight Services dedicated F9 launch. While initially ELV, small LV companies will most likely move to reuseable LVs to be more responsive and lower launch costs. They may start to grow and threaten lower end of main stream launch market.