I just don't see the proposed F5x5 as being anything more than a misstep in comparison to FH.Five smaller cores means all the necessary components to run each core are duplicated five times instead of three; smaller cores also run afoul of the cube-square law so they're most likely proportionately heavier for the volume of propellant carried.F5x5 also has fewer engines than FH, meaning less total thrust.I don't see the benefits of increasing complexity to reduce performance.
Quote from: Lemurion on 06/14/2016 02:52 pmI just don't see the proposed F5x5 as being anything more than a misstep in comparison to FH.Five smaller cores means all the necessary components to run each core are duplicated five times instead of three; smaller cores also run afoul of the cube-square law so they're most likely proportionately heavier for the volume of propellant carried.F5x5 also has fewer engines than FH, meaning less total thrust.I don't see the benefits of increasing complexity to reduce performance.So you'd rather have 2 non-modular rockets, instead? (likely meaning 2 rocket diameters)
And yet you suggested creating a complex set of various stages and an H2 stage on a Falcon rocket earlier. You've completely ignored all of SpaceX's strong points and made suggestions that all run counter to them.
Yes, a significantly less lucrative one. And a market full of "paper rockets" that never make it past development. Falcon 1 made it, and despite having invested in its design and manufacture, SpaceX ditched it, and with good reason. Investing in the Falcon 9 has been a smart long-term move. If the smallsat business was really all that lucrative, SpaceX would have kept the Falcon 1 in production.
“Many small satellites are being developed, requiring shorter development time and lower launch costs,” said Rachel Villain, principle advisor at Euroconsult. “On average each satellite is smaller at 2.1 tons (vs. 2.2 Tons). This average aggregates a growing number of small satellites (< 500 kg) from newcomer countries and smaller replacement satellites in LEO in established space countries.”
Quote from: fredinno on 06/14/2016 05:30 pmQuote from: Lemurion on 06/14/2016 02:52 pmI just don't see the proposed F5x5 as being anything more than a misstep in comparison to FH.Five smaller cores means all the necessary components to run each core are duplicated five times instead of three; smaller cores also run afoul of the cube-square law so they're most likely proportionately heavier for the volume of propellant carried.F5x5 also has fewer engines than FH, meaning less total thrust.I don't see the benefits of increasing complexity to reduce performance.So you'd rather have 2 non-modular rockets, instead? (likely meaning 2 rocket diameters)No, they'd rather have a 3-core instead of a 5-core for equivalent capacity, it's the trade-off between modularity/commonality and reduced complexity.
Considering it's expected to get pretty big, I would have taken the market before everyone else did, meaning SpaceX would get the max. $$ from that market.
Quote from: fredinno on 06/14/2016 08:01 pm Considering it's expected to get pretty big, I would have taken the market before everyone else did, meaning SpaceX would get the max. $$ from that market. Where is the data to support that claim? Spacex is ignoring it because there is no money in it.
1. http://www.euroconsult-ec.com/shop/space-industry/64-prospects-for-the-small-satellite-market.htmlhttp://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=3018&context=smallsat2. There IS money in it. Even SpaceX knows, they got that 27 satellite or so Oorbcomm contract for F1 right before they killed that rocket.
How do you know?
BTW, what's complex? I'd argue the 6-core variant has LESS complexity than Soyuz (considered a fairly cheap launcher), which has the same number of stages, but numerous different core diameters.It also has less complexity than Ariane 6, with 6 staging events, but using H2.Also, F9 isn't the pinnacle of simplicity. Replacing the 1st stage with a single Rp-1 engine would probably reduce costs per launch, since the reuse cancels the majority of the "mass production" benefit using 9 engines on the 1st stage had.
...A better idea is probably to have a 6-core config, to capture that last stretch of payload capacity from 5.5 to 7T to GTO.... or a 7-core config...
BTW, what's complex? I'd argue the 6-core variant has LESS complexity than Soyuz (considered a fairly cheap launcher), which has the same number of stages, but numerous different core diameters.
Also, F9 isn't the pinnacle of simplicity. Replacing the 1st stage with a single Rp-1 engine would probably reduce costs per launch, since the reuse cancels the majority of the "mass production" benefit using 9 engines on the 1st stage had.
Also, it would have made replacing satellites in SpaceX's internet sat constellation much cheaper, without having to launch a dedicated F9 for a few replacement spares.
You've officially jumped the shark here. The existing Falcon 9 (NOT Falcon Heavy) can lift 8.3 mT to GTO. You're talking about a six to seven core rocket to get the same performance. That is a laughably bad idea.
Quote from: Pipcard on 06/14/2016 05:45 pmQuote from: fredinno on 06/14/2016 05:30 pmQuote from: Lemurion on 06/14/2016 02:52 pmI just don't see the proposed F5x5 as being anything more than a misstep in comparison to FH.Five smaller cores means all the necessary components to run each core are duplicated five times instead of three; smaller cores also run afoul of the cube-square law so they're most likely proportionately heavier for the volume of propellant carried.F5x5 also has fewer engines than FH, meaning less total thrust.I don't see the benefits of increasing complexity to reduce performance.So you'd rather have 2 non-modular rockets, instead? (likely meaning 2 rocket diameters)No, they'd rather have a 3-core instead of a 5-core for equivalent capacity, it's the trade-off between modularity/commonality and reduced complexity.How do you know?
Quote from: Toast on 06/14/2016 10:27 pmYou've officially jumped the shark here. The existing Falcon 9 (NOT Falcon Heavy) can lift 8.3 mT to GTO. You're talking about a six to seven core rocket to get the same performance. That is a laughably bad idea.Again, just to clarify his position, all his estimated launch capacities are for reusable mode, not expendable mode.
Ok, what is so complex about multi-core configs?
None of it is unknown. Really, it's not even crossfeed. 5 cores are burning independently (potentially, the core might actually be started in flight- something required for SpaceX reuse anyways), with structural supports to the core, and a separation mechanism.
Whoopie, worst case scenario, the rocket is a bit more costly initially to develop. But it benefits from mass production of the cores, especially at the rosy regular launch scenarios Elon wants.
It also provides a back in case reuse doesn't pan out for some reason, and ends up being less economical than predicted. Right now, the F9 only really hits the 4-5T to GTO market, and the big, 6-8T to GTO market. Meanwhile, literally the entire LEO and MEO market needs to waste fuel and payload to launch on Falcon 9.
Ok, what is so complex about multi-core configs? None of it is unknown. Really, it's not even crossfeed. 5 cores are burning independently (potentially, the core might actually be started in flight- something required for SpaceX reuse anyways), with structural supports to the core, and a separation mechanism.Whoopie, worst case scenario, the rocket is a bit more costly initially to develop. But it benefits from mass production of the cores, especially at the rosy regular launch scenarios Elon wants. It also provides a back in case reuse doesn't pan out for some reason, and ends up being less economical than predicted. Right now, the F9 only really hits the 4-5T to GTO market, and the big, 6-8T to GTO market. Meanwhile, literally the entire LEO and MEO market needs to waste fuel and payload to launch on Falcon 9.Including Dragon, SpaceX's own vehicle. Reusable F9 carries ~13T to LEO under barge landings (slow). Dragons max out at 10T.I think I can safely conclude that I come from a very different community. This discussion is pretty much going in circles, and I don't want that to happen again, like with Pipcard a while ago.I'm not convincing you guys, and you guys aren't convincing me.I'm going to agree to disagree. No one will truely know until we get a dedicated report to it. Hopefully we do someday.
I'm not convincing you guys, and you guys aren't convincing me.I'm going to agree to disagree. No one will truely know until we get a dedicated report to it. Hopefully we do someday.
Right now, the F9 only really hits the 4-5T to GTO market, and the big, 6-8T to GTO market. Meanwhile, literally the entire LEO and MEO market needs to waste fuel and payload to launch on Falcon 9.