Author Topic: Fairing reuse  (Read 551529 times)

Offline Robotbeat

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Re: Fairing reuse
« Reply #420 on: 06/03/2016 08:25 PM »
Or use an airplane to recover them. Doesn't have to be a helicopter. Corona used airplanes. Seems like it'd be cheaper, faster, maybe safer. Airplanes are lower maintenance, can cover a much longer range, and SpaceX already uses them sometimes just for observing the booster recovery attempts.

Once a fairing halve is caught by the plane, however, I'm not entirely sure how it'd be gently placed on the ground.
« Last Edit: 06/03/2016 08:42 PM by Robotbeat »
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Offline Lar

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Re: Fairing reuse
« Reply #421 on: 06/03/2016 08:30 PM »
I agree that replacing the foam is probably cheaper than helicopters ... especially because you have to figure out how to base them at sea since they don't have the range/loiter to fly out 500 nm, loiter around through a whole launch cycle and return.

You can do in-air refueling of helicopters.

Basing them at sea.... whoa... I mean, we just figured out how to land a simple rocket on a ship, now suddenly you're talking about moving directly to something with huge spinning blades!
SpaceX optimizes for cost. Are you sure that in-air refueling of not one, but two, helos is going to be the cheapest way? If not, are you sure that basing them on a ship is going to be the cheapest?
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Offline sewebster

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Re: Fairing reuse
« Reply #422 on: 06/03/2016 08:43 PM »
I agree that replacing the foam is probably cheaper than helicopters ... especially because you have to figure out how to base them at sea since they don't have the range/loiter to fly out 500 nm, loiter around through a whole launch cycle and return.

You can do in-air refueling of helicopters.

Basing them at sea.... whoa... I mean, we just figured out how to land a simple rocket on a ship, now suddenly you're talking about moving directly to something with huge spinning blades!
SpaceX optimizes for cost. Are you sure that in-air refueling of not one, but two, helos is going to be the cheapest way? If not, are you sure that basing them on a ship is going to be the cheapest?

Don't forget the other helicopters with high speed cameras live streaming to the public!

Yeah, sorry, my whole post was basically supposed to be sarcastic. And I realize you were actually advocating against the ship-based concept. Here's the translation of my post:

"Basing helicopters on ships is pretty much a solved problem if they wanted to go that way... but I'm guessing they will try to avoid something like that if at all possible to reduce costs.

Offline arsenal

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Re: Fairing reuse
« Reply #423 on: 06/03/2016 09:15 PM »
Another factor is wind. Not sure how well the parachutes will be able to steer in heavy wind. There will probably be some severe restrictions to where you can aim the chutes based on the weather conditions.

Offline Kaputnik

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Re: Fairing reuse
« Reply #424 on: 06/03/2016 10:15 PM »
Do we genuinely think that splashing the fairing halves is a no-go? They must be relatively sturdy to withstand aero loads, and are nowhere near the size/scale of a first stage.
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Offline manoweb

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Re: Fairing reuse
« Reply #425 on: 06/03/2016 10:29 PM »
Kaputnik, I was under the impression that the expensive part of the fairings, the composite, can survive a splash down and not be damaged by saltwater.

Offline georgegassaway

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Re: Fairing reuse
« Reply #426 on: 06/03/2016 10:53 PM »
Or use an airplane to recover them. Doesn't have to be a helicopter. Corona used airplanes.
……
Once a fairing halve is caught by the plane, however, I'm not entirely sure how it'd be gently placed on the ground.

Fairings way too big and flimsy (once in separated halves) to use a plane.  Air-snag of satellites, they were around 3 feet diameter and very robust.

And even if they could survive, no way to land them gently as you noted (Discoverer/Coronas were winched inside of the open back section of a C-117 Flying Boxcar).

Another factor is wind. Not sure how well the parachutes will be able to steer in heavy wind. There will probably be some severe restrictions to where you can aim the chutes based on the weather conditions.

An airborne vehicle can “steer” fine once it is off the ground and into the air.  Wind direction and velocity is not a factor for steering.  Severe turbulence can be.

Keep in mind for example that if a hot air balloon is a few hundred feet up flying in 10 mph wind, from the perspective of those on board, the balloon is in calm air, while the ground is moving at 10 mph.

One good thing is that over the ocean there does not tend to be as much turbulence as occurs over land due to trees, buildings, mountains, and thermal activity from uneven heating of the ground.

With a smart enough autonomous steering system for chutes, it could turn into the wind to use a headwind for a slower landing into the water.  Say if a 30 mph glide speed and 15 mph wind, fly into the wind for a net 15 mph horizontal velocity (which of course human parachutists do, usually with some nearby wind direction indicator such as windsock or smoke canister).  There are various means that it could use to determine the wind direction while over the water, such as comparing the  GPS based horizontal velocity and  with the indicated airspeed, while in a wide circle (or flying a rounded-square pattern) to derive the likely wind direction and speed.

I am not saying I think landing by chute into the water is how they’d do it vs say grabbing in midair by helicopter.  Just noting that an airplane type of air-snag seems unfeasible, and that in the most basic sense wind does NOT make it harder to steer (Landing during a very serious storm, that would be a different issue, as that would be a problem for any system.  Any air-snag during a storm, a risk of mid-air collision and loss of crew. ).  If K.I.S.S. rules, then chutes into water would seem the most practical. Unless there's a really big reason why salt-water landing is not good even though they are mostly composite (since they are not 100.00% composite, possibly some critical not-practical-to-replace components might be affected)

However, I just got to thinking about the aerodynamic interaction of  steerable chutes and the relatively lightweight  very large fairings.   I would hope that the suspension lines would put the fairing at a horizontal or near horizontal angle, in such a way that the rear edges of the fairing would act like rudders to keep the fairing pointed into the wind. Otherwise might need a little tail chute at the back of the fairing to keep the nose pointed into the airflow, as often used with long-distance helicopter transport of cargo to keep it from spinning around.
« Last Edit: 06/04/2016 05:05 AM by georgegassaway »

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Re: Fairing reuse
« Reply #427 on: 06/03/2016 11:05 PM »
You can probably can get between a 4/1 to 8/1 glide ratio off the parachutes.  It really depends on how much weight you want to use for the parachutes.  The other downside to a better glide ratio, other than weight, is the ability to glide into the wind.  If the wind is too high for the glide ratio you might actually be going backwards.  Although it is probably the most desirable to glide all the way back to the ship probably the best reason to have them glide is so they can meet at the same known points for recovery.

So depending on deployment height/winds they could possibly glide for as little as 4 miles with a 4/1 and deployment at 5000 feet.  If deployed at 35,000 to 45,000 feet you could possibly get between 25 and 50 miles.  You could definitely employ them higher than this but it might not gain you as much as you might think.  The glide ratios at let’s say 80,000 feet might be closer to 1/1 and would leave them subjected to high-altitude wind’s.  It might be better to get through these wind’s faster than trying to glide through them.

It has got to be cheaper, not to mention less costly, to try to find and recover 2 mostly submerged/bobbing fairings a quarter-mile from each other (at a predetermined known location) than to try to find those same fairings someplace within 100 square miles separated by something like 50 miles of ocean.

I really don’t see how the fairings can be so damaged by a little immersion in salt water that it could possibly justify the cost of a helicopter recovery.  And really what you’re talking about here is 2 long-range helicopters.  Most of the parts should be safe from a little salt water immersion, they would just get rinsed off once they’re on board the ship.  The few parts that absolutely can’t be made to tolerate the salt water have just got to be cheaper to be replaced than the cost of a helicopter recovery.

Offline friendly3

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Re: Fairing reuse
« Reply #428 on: 06/04/2016 01:12 AM »
The few parts that absolutely can’t be made to tolerate the salt water have just got to be cheaper to be replaced than the cost of a helicopter recovery.

No, the few parts that absolutely can’t be made to tolerate the salt water and the cost of a boat recovery have just got to be cheaper to be replaced than the cost of a helicopter recovery.

Offline oiorionsbelt

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Re: Fairing reuse
« Reply #429 on: 06/04/2016 01:18 AM »
Seems as though ya just need to get them down rather gently and pick em up rather quickly.

Online tleski

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Re: Fairing reuse
« Reply #430 on: 06/04/2016 03:06 AM »
Seems as though ya just need to get them down rather gently and pick em up rather quickly.

I think the first photo (the one with the flag) shows a fragment of the interstage, not fairing.
« Last Edit: 06/04/2016 03:06 AM by tleski »

Online CJ

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Re: Fairing reuse
« Reply #431 on: 06/04/2016 03:28 AM »
Something to bear in mind regarding helicopters (or planes, for that matter); range does not mean the same thing for military craft as it does for civilian. The military definition is usually out and back, whereas the civilian is one-way.

Another factor with helicopters; is they are carrying their cargo underslung (outside), range will be significantly decreased over carrying it internal.

Here's an article of how NASA tried to do a mid-air retrieval, via helicopter, of the Genisis probe.  (that's the one that crashed due to chute failure). http://www.space.com/281-sky-capture-nasa-bring-genesis-earth.html

So, seeing as how the fairings would tend to come down not too far (50 miles?) from the ASDS on non-boostback-burn missions, I wonder if it's feasible to use the ASDS as a launch point for the helicopters; they ride out on the ASDS, take off a few minutes before launch, snag the fairings, and lower them to either the support ship or ASDS deck. (I strongly suspect the former.) and then fly to shore.  You'd need helicopters with longer than normal range (some have that kind of range, and others can have an extra fuel tank added). I think the timing would be pretty daunting, so perhaps it'd be better (also from a cost perspective, perhaps) to emulate what the Air Force did way back in 1960 and after; use a cargo plane. 

Online Comga

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Re: Fairing reuse
« Reply #432 on: 06/04/2016 04:20 AM »
(snip)
So, seeing as how the fairings would tend to come down not too far (50 miles?) from the ASDS on non-boostback-burn missions, I wonder if it's feasible to use the ASDS as a launch point for the helicopters; they ride out on the ASDS, take off a few minutes before launch, snag the fairings, and lower them to either the support ship or ASDS deck. (I strongly suspect the former.) and then fly to shore.  You'd need helicopters with longer than normal range (some have that kind of range, and others can have an extra fuel tank added). I think the timing would be pretty daunting, so perhaps it'd be better (also from a cost perspective, perhaps) to emulate what the Air Force did way back in 1960 and after; use a cargo plane. 

At the risk of going farther down the rabbit hole....
A big problem with staging helicopters from the ASDS is what happens if they fail to take off?  They would have people and a helicopter on the ASDS. That would probably mean calling off the booster recovery.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline The Amazing Catstronaut

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Re: Fairing reuse
« Reply #433 on: 06/04/2016 04:55 AM »
Salt water isn't really good for anything metallic (see STS SRBs), but helicopters cut into the fairing reuse cost. Are we completely sure that helicopter recovery is what they intend to do? Are there any alternative methods for ensuring the fairing doesn't end up in the drink?

Edit: If air recovery truly is the way to go, a fixed winged aircraft does indeed seem preferable. Helicopters are not fun to fly far over water notwithstanding. A pity there isn't a sufficiently large drone.
« Last Edit: 06/04/2016 04:59 AM by The Amazing Catstronaut »
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Offline IntoTheVoid

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Re: Fairing reuse
« Reply #434 on: 06/04/2016 05:29 AM »
Why not just use JPADS and land the fairings on their own ASDS. The 10,000 lb version is already called DragonFly. Could be confusing, but their heart's in the right place.   ::)

https://en.wikipedia.org/wiki/Joint_Precision_Airdrop_System
http://www.militaryaerospace.com/articles/2014/04/computer-parachute-airdrop.html

Online CJ

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Re: Fairing reuse
« Reply #435 on: 06/04/2016 05:31 AM »
(snip)
So, seeing as how the fairings would tend to come down not too far (50 miles?) from the ASDS on non-boostback-burn missions, I wonder if it's feasible to use the ASDS as a launch point for the helicopters; they ride out on the ASDS, take off a few minutes before launch, snag the fairings, and lower them to either the support ship or ASDS deck. (I strongly suspect the former.) and then fly to shore.  You'd need helicopters with longer than normal range (some have that kind of range, and others can have an extra fuel tank added). I think the timing would be pretty daunting, so perhaps it'd be better (also from a cost perspective, perhaps) to emulate what the Air Force did way back in 1960 and after; use a cargo plane. 

At the risk of going farther down the rabbit hole....
A big problem with staging helicopters from the ASDS is what happens if they fail to take off?  They would have people and a helicopter on the ASDS. That would probably mean calling off the booster recovery.

Hrmmm. I think you're right - they'd have to skip the F9 recovery. That, plus other factors (such as the tight margins for them getting back to land) probably make this a bad idea.

A fixed wing old cargo plane, on the other hand, would be easier, cheaper, and not potentially hinder F9 recovery. Water recovery would be even better IMHO, if (and that's a mighty big if) the fairings can tolerate salt water landing and immersion.




Online OnWithTheShow

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Re: Fairing reuse
« Reply #436 on: 06/04/2016 05:39 AM »

Quote

Hrmmm. I think you're right - they'd have to skip the F9 recovery. That, plus other factors (such as the tight margins for them getting back to land) probably make this a bad idea.


Plenty of ships with helipads out there to rent.

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Re: Fairing reuse
« Reply #437 on: 06/04/2016 05:46 AM »
They can use a ship with helipad. But what when they have caught the bus? The helicopter would likely not have the range to get to land from there. How to land the fairing under parachute on a ship? Something with a flat area as large as the big barges may be needed. It would not necessarily need station keeping thrusters.

Offline Kaputnik

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Re: Fairing reuse
« Reply #438 on: 06/04/2016 05:52 AM »
Are we completely sure that helicopter recovery is what they intend to do?

No, everything is speculation at this point.
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Re: Fairing reuse
« Reply #439 on: 06/04/2016 02:28 PM »
As with most experiments on recovery that SpaceX does, they start with the simplest/cheapest options they can think of and only add more complexity/cost when they find those solutions are not tenable/optimal.  At the moment the simplest/cheapest option would appeared to let the fairing just splash into the ocean and then tow them back to land or possibly to the barge.  Even if SpaceX ultimately thinks this may not be the final working solution this is probably where they will start until they actually get fairings back and see how they fare their ordeal.  This is how they are doing it with the returning stages. After they have these fairings in hand and can inspect them only then will they determine what additional modifications they might make.  So even if SpaceX is thinking that they might need to ultimately use aircraft retrieval for these fairings the 1st recoveries we observe will still probably be those from the ocean.

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