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That was interesting, All that flame on the side booster seems like it wasn't planned? And did anyone else notice the pretty wild trajectory changes at "closed loop guidance" and at side booster cutoff? Seemed like a pretty large change in direction.
And notice ULA has "upped their game" on coverage- accept for the NROL's request of no 2nd stage video
And notice ULA has "upped their game" on coverage- accept for the NROL's request of no 2nd stage video
Flames are normal.
Closed loop attitude change was just a roll, probably to align the vehicle for side booster separation
Trajectory change after side booster sep was interesting. Seemed like a pitch up, possibly just a function of F=ma (more or less). With the extra mass of the side boosters that late in their life it may be more beneficial to fly more horizontal and increase velocity more rather than than use the thrust to increase altitude?
I had not watched a Delta Heavy broadcast before. When the side booster was jettisoned and fell away, for a moment I thought “Where is the boost back burn?”. Oh wait…
Did you notice how there seemed like a 1 second video missing when the side boosters detached? I saw it in 0.25 speed and you will notice in one frame the booster is firmly attached, and the very next frame it is atleast 100 feet away.
It was cool to see the 2nd stage engine nozzles expand and slide out after MECO.
Also what happened to the telemetry on the screen? Even the countdown timer disappeared at T-30?
These are the two frames right next to each other captured at 0.25 speed
It was cool to see the 2nd stage engine nozzles expand and slide out after MECO.
Also what happened to the telemetry on the screen? Even the countdown timer disappeared at T-30?
These are the two frames right next to each other captured at 0.25 speed
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Yes they are normal as per the commentator who explains the sequence for the last 10 seconds. At T-7, they burn of any excess H2 near the base of the booster.
That camera had some other stutters as well. For example at 53:47 (a few secs after launch) it appears to have dropped a few frames...
And those "dynamic nozzles"... I had thought about such a thing previously for allowing the same engine to operate both at sea-level and in a vac. In this case it appears it's just for space savings?
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Yeah, its mostly just to get the expansion ratio way up without resulting in a lot of sub-optimized rocket volume. Its quite clever, but IMO its a bit of a solution looking for a problem. I guess every trade has its own priorities but when I 0th order the downside of cost and complexity with the upside of mass and volume, its hard for me to imagine the extension really being the ideal solution. Of course, ESA disagrees with that even in the world of new news engines (rather than the world of evolving the 1960's RL10)--they're planning on the same kind of extension for Vinci, the A6 upper stage motor.
Anyway, for the RL10, the engine and fixed part of the nozzle are almost fully enveloped by the stowed nozzle extension. Makes sense--if you'r making an extension you might as well make it as big as practical.
Interesting.... so in that video it was deployed for the second stage engine before it lit, so it was just space savings right?
I was thinking of Starship with it's 3 sea-level + 3 vac Raptors.... is it plausible to use a similar "extending nozzle" design to allow the same engines to work in both regimes? Has that ever been done?
Yup. The nozzle gets to be ~as long again as the length of the motor's pumpy bits + chamber + expander part of the nozzle. Just did a quick lookup and the expansion ratio ~doubles from current generation fixed nozzles.
Somewhat related: Scott Manley talks about the RL-10. Different video clip in there of the nozzle extending.
There probably are concepts for dual use, but I don't think its ever actually been done...at least not for any useful vehicle. Good bit of risk there and kinda difficult to actually close the technical trade. Ship is certainly the closest thing to a use case for the concept and you have to assume SX thought about it when implementing the 3+3.
Armchair engineering here, In a world where there were just three extendo-vac motors they would still need to be pretty far apart to account for the big vac bells + gimbaling clearances (***perhaps not the latter if there's some clever solution that has the extendo-bells fixed and then the sea-level bells gimbal within their volume?), and intuitively the more axially offset thrust vectors could be real problematic on landing, especially if there's a flameout. So...maybe you put a single sea-raptor in the middle? But then you have to close the trade of the additional cost/mass/complexity of 3x extendo-bells versus the 3.2T you saved by nuking two sea-raptors.
However, it would seem that, using the 3+3 example, the clearance for 3 gimbling motor/nozzles would need to be maintained with an additional 3 stationary large vac nozzles in the same space. Assuming the gimbling angles are not severe, it's hard to imagine the extendo-nozzle solution not taking up less space.
I'm sure, as you mention. there are other engineering challenges I'm not thinking of... but if you can makes sure the extension deploys/seals properly as has already been done, it would seem that it would also be easy to operate it in "unextended" mode...
I'm sure, as you mention. there are other engineering challenges I'm not thinking of... but if you can makes sure the extension deploys/seals properly as has already been done, it would seem that it would also be easy to operate it in "unextended" mode...
For sure--if in sea mode they can gimbal within the volume of the stowed vac nozzles then three vac motors could be moved radially inward relative to where they currently are in the 3+3. Their minimum spacing would be a function of the vac bell diameter (+ some dynamic/thermal clearances) and would be largely if not completely decoupled from the fact that they're extension nozzles.
The [not well articulated above] question still remains: Would the three motors be close enough in gimbaling sea mode to satisfy the landing flight envelope? Certainly there's a point in a one-engine landing where Ship would have to pitch so far over to ~align the single motor's thrust vector with the vehicle CG that actually landing the thing would become untenable.
Yeah, good point... and something you referred to in your previous post.
It seems that the 3-enging Starship belly-flop tests had a bit of canted angle to them, ostensibly from the off-center thrust of 1-2 of the tri-engine setup... spacing them farther apart would indeed exacerbate that...
Turns out Atlas V had a launch yesterday. Subjectively, if not less than important, the 5m Atlas is always goofy to look at...if F9 was a 747, a 5m Atlas would be...an A380...
Anyway, some decent/interesting images from the feed (classic fairing flexing after deployment, etc.) but otherwise pretty stock. Payload was two medium sized, pretty basic GEOs for SES. Of note one was directly stacked on top of the other, which is something that's relatively new in the industry. The upside is that it eliminates the mass/complexity/cost of having a proper dual launch structure (like Ariane's Sylda, for instance). The downside is that the earth face of the bottom satellite has to be significantly less complex/populated than it could otherwise be, since the face is dominated by a cylindrical structure that supports the upper sat. The bottom sat also has to be structurally enhanced, since its the load path for the upper sat.
Note that its almost certain these two sats are identical or at least near identical, allowing SES to amortize NRE across two sats.
Anyway, some decent/interesting images from the feed (classic fairing flexing after deployment, etc.) but otherwise pretty stock. Payload was two medium sized, pretty basic GEOs for SES. Of note one was directly stacked on top of the other, which is something that's relatively new in the industry. The upside is that it eliminates the mass/complexity/cost of having a proper dual launch structure (like Ariane's Sylda, for instance). The downside is that the earth face of the bottom satellite has to be significantly less complex/populated than it could otherwise be, since the face is dominated by a cylindrical structure that supports the upper sat. The bottom sat also has to be structurally enhanced, since its the load path for the upper sat.
Note that its almost certain these two sats are identical or at least near identical, allowing SES to amortize NRE across two sats.
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