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#480 by tyrred on 23 Dec, 2017 05:58
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Will there be camera on the side booster? Consider where the nose cone begins, it is hard for a downward facing camera to observe those gird fins.
Looking closely at the inboard nosecones, are those camera pods on each, facing downwards towards the yellow linkage apparatus? Perhaps I'm wrong, but it seems like a good place to situate a camera (to a layman). -
#481 by Johnnyhinbos on 23 Dec, 2017 08:12
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#482 by macpacheco on 23 Dec, 2017 08:28
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The Titanium fins are installed on the side boosters to give them better glide ratio, reducing the duration of the boost back required that still gets the boosters to the LZ.
Since the center core lands on ASDS, they might handle the higher re-entry speed with a longer entry burn.
Just educated guesses, but it actually makes sense. -
#483 by zhangmdev on 23 Dec, 2017 10:05
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Looking closely at the inboard nosecones, are those camera pods on each, facing downwards towards the yellow linkage apparatus?
The angle seems wrong. Grid fins and legs are likely outside field of view. But maybe they are more focused on observing how upper part of separation mechanism behaves. If they have side viewing cameras to document lower part of separation and keep recording all the way to touchdown, that would be awesome.
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#484 by clongton on 23 Dec, 2017 12:35
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Can someone explain why they didn't use the Tangent Ogive shape of the Ariane 5 booster?
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#485 by Rocket Science on 23 Dec, 2017 12:42
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Can someone explain why they didn't use the Tangent Ogive shape of the Ariane 5 booster?
My only theory is for boundary layer/flow separation symmetry and controlabilty for landing (as it then becomes a "boatail" during entry and approach) and maintain known flight control algorithms from Falcon 9 S1... However; I have no actual aero data to compare both during descent to back it up... I don't believe they are going to jettison the nose cone AFAIK.... -
#486 by nacnud on 23 Dec, 2017 12:50
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Can someone explain why they didn't use the Tangent Ogive shape of the Ariane 5 booster?
Maybe it's from the experiences with Titan and Shuttle that have conic booster nose cones. With the nose cones on the Ariane V aerodynamic forces are always going to be pushing the booster into the stage. Maybe the force produced with conic booster nose cones depends on the speed of the booster and can vary more. So harder to deal with.
At least that is what I think.
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#487 by Rocket Science on 23 Dec, 2017 13:02
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With that in mind, it is interesting to note the current booster for SLS and the proposed "Dark Knight" configuration...Can someone explain why they didn't use the Tangent Ogive shape of the Ariane 5 booster?
Maybe it's from the experiences with Titan and Shuttle that have conic booster nose cones. With the nose cones on the Ariane V aerodynamic forces are always going to be pushing the booster into the stage. Maybe the force produced with conic booster nose cones depends on the speed of the booster and can vary more. So harder to deal with.
At least that is what I think. -
#488 by Herb Schaltegger on 23 Dec, 2017 13:05
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Elon just tweeted this...
https://twitter.com/elonmusk/status/944495421161742336
For those who don't do Twitter:QuoteIf you liked tonight’s launch, you will really like Falcon Heavy next month: 3 rocket cores & 3X thrust. 2 cores return to base doing synchronized aerobatics. 3rd lands on droneship.
3:10 AM - 23 Dec 2017
That's a lot more confident-sounding than prior statements. -
#489 by Lar on 23 Dec, 2017 13:23
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Can someone explain why they didn't use the Tangent Ogive shape of the Ariane 5 booster?
Because Ariane 5 doesn't care about recovering the side boosters? They will have off kilter aerodynamics due to the strong asymmetry.
Also because reducing loads on the core may not be as important to this vehicle as it is to Ariane 5? -
#490 by nacnud on 23 Dec, 2017 13:25
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Because Ariane 5 doesn't care about recovering the side boosters?
Ariane 5 booster are recoverable, but it's not often done.
http://www.esa.int/esapub/bulletin/bullet85/gigo85.htm -
#491 by clongton on 23 Dec, 2017 13:30
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With that in mind, it is interesting to note the current booster for SLS and the proposed "Dark Knight" configuration...Can someone explain why they didn't use the Tangent Ogive shape of the Ariane 5 booster?
Maybe it's from the experiences with Titan and Shuttle that have conic booster nose cones. With the nose cones on the Ariane V aerodynamic forces are always going to be pushing the booster into the stage. Maybe the force produced with conic booster nose cones depends on the speed of the booster and can vary more. So harder to deal with.
At least that is what I think.
Yea I forgot about that. But you're right. The Dark Knight nose cone is essentially the same as the Ariane 5 booster nosecone.
As for pushing the booster toward the core, the Poles had an easy solution to that on their Meteor-2K rocket - simply rotate the cone around 180 degrees, which might even improve the whole concern.
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#492 by clongton on 23 Dec, 2017 13:34
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Because Ariane 5 doesn't care about recovering the side boosters?
Ariane 5 boosters are recovered.
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#493 by nacnud on 23 Dec, 2017 13:36
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Also because reducing loads on the core may not be as important to this vehicle as it is to Ariane 5?
I was wondering this too. In the shuttle the boosters lift from their tops so there is a strong cross beam there able to withstand high loads. Falcon booster lift from the bottom, I don't know about Ariane 5 but looking at cutaways I think the boosters lift from the bottom as there is no crossbeam at the top of the booster as with the shuttle ET. I have even less idea about the Titan IV. -
#494 by Lar on 23 Dec, 2017 14:19
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Because Ariane 5 doesn't care about recovering the side boosters?
Ariane 5 boosters are recovered.
But not reused?QuoteThe possibility of refurbishing and reusing the recovered boosters has, however, been rejected. It is currently considered a non-cost-effective option because of the specific design and reliability complications that this would incur. It is currently planned to recover four boosters per year.
(from http://www.esa.int/esapub/bulletin/bullet85/gigo85.htm cited above by nacnud.)
Why bother? Seriously. There might be some minor learnings but if you're not even going to TRY to reuse them, it's just a big boondoggle. Some contracts must have been let and then found to be too expensive to cancel, or something. -
#495 by nacnud on 23 Dec, 2017 14:31
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Why bother? Seriously. There might be some minor learnings but if you're not even going to TRY to reuse them, it's just a big boondoggle. Some contracts must have been let and then found to be too expensive to cancel, or something.
You could have said the same about reusing the shuttle boosters, IIRC the refurbishment cost was quite close to the cost of just building new each time. The reason for getting them back on occation is engineering data, validating the design.
While it's obvious now the way to get to reuse is liquid boosters as the refurbishment cost is lower having the Ariane booster solid kept the knowledge of how to build large solid alive in Europe. And solids are great when it comes to sitting inert in silos for extended periods of time...
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#496 by Lar on 23 Dec, 2017 15:22
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You could have said the same about reusing the shuttle boosters (snip...)
It would be hard to prove now but I beleive I DID say exactly that, way back in the day. -
#497 by Lars-J on 23 Dec, 2017 15:42
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Can someone explain why they didn't use the Tangent Ogive shape of the Ariane 5 booster?
Because that would make the booster hard to fly and land on its own. (Imagine trying to land a plane with a tail rudder permanently angled to one side)
Also it that ULA is moving away from booster nose cones like that (the upgraded Atlas V SRBs have plain conical nose cones), so the benefits of them are clearly not significant. -
#498 by zhangmdev on 23 Dec, 2017 16:22
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I remember someone said an SRB is virtually unsinkable after splashdown, if not retrieved those two giant steel casing floating around could be hazardous to shipping.
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#499 by Space Ghost 1962 on 23 Dec, 2017 17:17
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Can someone explain why they didn't use the Tangent Ogive shape of the Ariane 5 booster?
Flight frequency? Need? Development schedule overload? Lifetime of vehicle?
Never really thought that FH has gotten the same amount of attention that F9/BFS/BFR have had.
It started out as "Falcon 9 Heavy" as a simple expedite, in part to launch those Iridium missions like last night. (I wonder if they just had bolted together three F9 1.0's and flown them as if a single expendable booster no separation of boosters, and accept the non optimality to begin.)
Instead, more like BO, they've obsessed with single core performance with enhanced engines, and the FH program has evolved constantly til the point that SLC-4E's TEL, which was intended to fly it, couldn't.
FH has become one of the last steps of the Falcon launch vehicle family, probably done before block 4/5 because you'd want to have the vehicle operational so you can apply the flight history to the reuse improvements for them to both share the FH/F9 economics closely (very much unlike DIVH which was much more problematic).
Possibly if FH has more applicability (like in the case of lunar free return flights?), the tangent ogive's might be factored in.
As for Ariane, it only flew/flies with the side boosters, so all considerations for the entire vehicle were from the start.My only theory is for boundary layer/flow separation symmetry and controllabilty for landing (as it then becomes a "boatail" during entry and approach) and maintain known flight control algorithms from Falcon 9 S1.
Nope. What it would do is change the area affected by the larger grid fins, shifting the center line off center.
The vehicles already have to compensate for asymmetries, and on the F9 RTLS they have been using greater angle of attack on the boosters, which provokes a similar asymmetry, which the guidance software deals with as well as things like crosswinds.They will have off kilter aerodynamics due to the strong asymmetry.
Not really.
Just shifts CP going up, shifts "ineffectual" area coming down (you could lengthen the fins still more to compensate if you needed even more control authority above transonic, but I doubt it -- it's not going to tumble
).QuoteAlso because reducing loads on the core may not be as important to this vehicle as it is to Ariane 5?
Reducing loads on the boosters means better mass fraction for all F9 boosters.
Side compressive loads on the booster core is the typical load holding the stack together, when you need it lower to max Q - the side TO cancels across the core's transverse loads bottom to top.Also it that ULA is moving away from booster nose cones like that (the upgraded Atlas V SRBs have plain conical nose cones), so the benefits of them are clearly not significant.
The greater area/faster/longer duration of flight, the more it helps.
The benefit would be better mass fraction. If you fly enough, perhaps it matters. And its something you can do later if you want.
add:
Investigating the staging velocity and necessary choice implied, the height of the optimal tangent ogive would be above the core interstage, so perhaps there might be clearance issues with the core's gridfins that might complicate matters too.
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