If you add the u/s stretch, presumably both of those numbers become obsolete. The FH one possibly before the first time it flies.
It doesn't matter whether you can transport 220' towers *somewhere*. The issues is the maximum load length possible on coast-to-coast routes between Hawthorne, McGregor, and the Cape.
I'm not buying it. Look up Tonopah, NV,and U.S. 95. Small town, mountainous terrain. That's where I've seen those 212' long towers being pulled...
How are the wind turbine components transported?Transport of such large items and the cranes needed to assemble them often presents problems in the remote areas where they are typically built. Roads must be widened, curves straightened, and in wild areas new roads built altogether.
I'm not buying it. Look up Tonopah, NV,and U.S. 95. Small town, mountainous terrain. That's where I've seen those 212' long towers being pulled. Unless there are major obstacles right outside the front gates of either Hawthorne, McGregor (which is a pretty wide open space, so not likely there) or Cape Canaveral, I doubt there will be any on the interstate route in between.
Quote from: Herb Schaltegger on 03/05/2015 01:43 amQuote from: Robotbeat on 03/05/2015 01:14 amWait, is it quite true, though, that 120' is such a hard (okay, "firm") limit? I got the idea that length has a much less firm limit than height, which obviously over any distance greater than a few miles has serious issues due to bridges. I mean, once you're on the Interstate, it's not like there are that many sharp turns.On-ramps and off-ramps, however, present all manner of pain-in-the-ass problems for transporting long objects.How often would that be necessary?Anyway, this is all a good argument for Return to Launch Site.
Quote from: Robotbeat on 03/05/2015 01:14 amWait, is it quite true, though, that 120' is such a hard (okay, "firm") limit? I got the idea that length has a much less firm limit than height, which obviously over any distance greater than a few miles has serious issues due to bridges. I mean, once you're on the Interstate, it's not like there are that many sharp turns.On-ramps and off-ramps, however, present all manner of pain-in-the-ass problems for transporting long objects.
Wait, is it quite true, though, that 120' is such a hard (okay, "firm") limit? I got the idea that length has a much less firm limit than height, which obviously over any distance greater than a few miles has serious issues due to bridges. I mean, once you're on the Interstate, it's not like there are that many sharp turns.
Quote from: MP99 on 03/05/2015 12:37 amIf you add the u/s stretch, presumably both of those numbers become obsolete. The FH one possibly before the first time it flies. Is a second stage stretch confirmed?Some have speculated that the added 10% volume can be done without a stretch.For example:http://forum.nasaspaceflight.com/index.php?topic=36815.msg1340204#msg1340204
Quote from: Dave G on 03/05/2015 10:27 amQuote from: MP99 on 03/05/2015 12:37 amIf you add the u/s stretch, presumably both of those numbers become obsolete. The FH one possibly before the first time it flies. Is a second stage stretch confirmed?Some have speculated that the added 10% volume can be done without a stretch.For example:http://forum.nasaspaceflight.com/index.php?topic=36815.msg1340204#msg1340204All I see in that post is a clear indication of a stage becoming longer with time.+10% vol means stretched, period.
Actually, upper stage tank volume +10% does not necessarily mean the outer structure needs to be stretched. A good example is the good old Ariane 4 - its LH2 third stage was modified twice in history (first flight 1988, first modification in 1992 and the second in 1994) to allow for slight increases in the fuel capacity with just internal tank stretches of inches. Each stretch brought about 100-150 kg increase in GTO payload capacity.
Yes, but the graphic shows that the first two stretches did, in fact, grow the overall length of the stage.Only the final stretch maintained the same stage length, by tweaking the tanks and skirt lengths by a few centimeters. The scale of the tank growth anticipated on F9 is more consistent with the first two stretches shown in the diagram, both of which increased stage length.
No confirmation that I've seen.
Quote from: Kabloona on 03/05/2015 01:46 pmNo confirmation that I've seen.You mean confirmation besides Elon Musk saying it in a Twitter?
Quote from: llanitedave on 03/05/2015 02:19 amI'm not buying it. Look up Tonopah, NV,and U.S. 95. Small town, mountainous terrain. That's where I've seen those 212' long towers being pulled... From the link you provided earlier:https://www.wind-watch.org/faq-size.phpQuoteHow are the wind turbine components transported?Transport of such large items and the cranes needed to assemble them often presents problems in the remote areas where they are typically built. Roads must be widened, curves straightened, and in wild areas new roads built altogether. So it appears that, while there's no fixed limit, longer stages would tend to present more issues with road transport.In any case, an informative discussion.
Sigh. Yes, we know Elon has tweeted that tank volume will increase by 10%. That's why we're having this discussion. The question is whether that will result in a length increase in the overall stage. I believe it will. Others believe it will not. But no one from SpaceX has confirmed what the actual effect on overall stage length, if any, will be.
How long are the second stage tanks, without engine, just the tanks? That gives how much in cm a 10% stretch is.
Everything can be imagined or speculated: bulges, external auxiliary tanks, modified pressurization with removal of He COPV tanks etc...But a one meter stretch of the stage is so simple that "+10% vol" can't mean anything different.
Quote from: guckyfan on 03/05/2015 02:11 pmHow long are the second stage tanks, without engine, just the tanks? That gives how much in cm a 10% stretch is.About 9 meters, consistently with 90 t propellant load.
A different meaning that could, hypothetically, be possible:Chilled LOX gets more "densification gains" than chilled RP-1 (~9% vs. ~5%, respectively), thereby altering the balance of prop:LOX to excess LOX when tanks are full. Additionally, increased thrust M1d may also have optimum performance with an altered fuel mixture (slightly less LOX). -----> Between higher density and lower fuel mix, less LOX volume is needed. Current tank sizes are no longer optimized and moving the bulkhead to increase RP-1 tank volume (at the expense of LOX tank volume) re-establishes optimum. +10% vol (in RP-1 tank) without stage stretch.
Sigh. Yes, we know Elon has tweeted that tank volume will increase by 10%. That's why we're having this discussion. The question is whether that will result in a length increase in the overall stage. I believe it will. Others believe it might not. But no one from SpaceX has confirmed what the actual effect on overall stage length, if any, will be.