Catching a falling rocket with a helicopter more complex than it sounds, says Rocket Lab

Private launch outfit Rocket Lab has again failed to catch one of its Electron launcher's first stages with a helicopter as it floated back to Earth. "Bringing a rocket back from space is a challenging task and capturing it mid-air with a helicopter is as complex as it sounds," said Rocket Lab founder and CEO, Peter Beck. "The …

[Anonymous Coward]

Which is it?

"Bringing a rocket back from space is a challenging task and capturing it mid-air with a helicopter is as complex as it sounds," said Rocket Lab founder and CEO, Peter Beck.

Whereas the title says "Catching a falling rocket with a helicopter more complex than it sounds, says Rocket Lab".

Title is stretching the truth for clicks, methinks.

[Evil Auditor]

Re: Which is it?

While I tend to agree with you, it didn't help that my brain read "catching a falling rock with a helicopter" and thought someone completely lost their mind to describe a rocket as a rock. Oh well

[Yet Another Anonymous coward]

Re: Which is it?

Arguably catching a rock coming from space with a helicopter is even harder

[Pirate Dave]

Re: Which is it?

My first thought was that the rocket was in free fall, not tied to a parachute, which seemed pretty impossible except in the movies. Not that catching a parachuting rocket would be that much easier.

[Blazde]

Re: Which is it?

I vote for: "Catching a falling rocket with a helicopter is more complex than catching a falling helicopter with a rocket"

[Sceptic Tank]

In these days of **magnets** and miracles, why do they try to hook a falling rocket? This sounds a lot like mid-air aircraft refueling. Or bring it down somewhere in the red dust north of Delmore Downs so you can retrieve it with a Land Rover.

[Anonymous Coward]

If you put the hardware you need to make an electromagnet that strong the helicopter probably wouldn't be able to take off, let alone carry that and the rocket.

And that's before asking whether there's sufficient material (and in sufficient thickness) in the rocket that the magnet would be able to hold on, let alone support the rocket's weight.

[John Brown (no body)]

Thunderbirds had magnets strong enough to carry entire aircraft!! And that was back in the 1960;s :-)

[FrogsAndChips]

Upvoted for the Pink FLoyd reference!

[Filippo]

Can't help noticing that most commenters seem to have missed it.

[imanidiot]

Not an option

They're using all their fuel to get the payload where it needs to go. They don't have the margins like SpaceX does to do a return, re-entry and landing burn. Basically the only option they have is to open a parachute after the rocket did it's thing and starts falling. Since it's flight path doesn't pass over the Delmore Downs, there's no option to land there. They have to either pluck it out of the air where it falls, or pick it up out of the ocean where it falls. Mid-air aircraft refueling is a lot simpler. Both aircraft are actively controlled and it's relatively easy to take the time to set up a rendezvous, keep both aircraft on the same flight path and get close, etc. In the case of catching a rocket stage, it falls under parachute where the flight path and prevailing winds take it. The helicopter pilots have the time between the chutes opening and getting the first position fix until it hits the ocean to get to it and make a pass over the top with the hook on the trailing line in the right position to catch rocket. That's really no easy feat. *magnets* aren't magic or miraculous and are not going to help here.

[MachDiamond]

Re: Not an option

"They don't have the margins like SpaceX does to do a return"

It's more about the rocket being more capable than necessary for a given mission rather than "margin". It takes roughly 45% more capability to re-land a first stage over one that will just be dropped in the drink. This is why rocket reuse has been a financial consideration for much longer than it has been a technical one. It takes a bunch of reuse to break even (~10 flights or so). If the market isn't that big for launches, the costs don't work out. With SpaceX launching their Falcon 9 most of the time in support of their internal Starlink constellation, they have some advantages with reusability. The advantages will only be realized if Starlink can earn a profit so there is some downside there if they don't hit some pretty nebulous goals.

[imanidiot]

Re: Not an option

No, it's about margins/mass-fractions.Only a tiny fraction of a Launch ready Falcon 9 is empty mass of the rocket, which means that it needs a comparatively tiny amount of that fuel weight remaining to make a propulsive landing. This is helped by the fact it'll likely very rarely be carrying a payload close to it's max capacity as it's been over engineered in terms of thrust to weight. The fuel to empty weight mass fraction on Electron is far more marginal, so it needs every ounce/milliliter/Walnut of fuel in case one or more of it's engines is slightly under performing even a little bit (which is common). Electron doesn't have the margins to bring more than the bare minimum of fuel it might need to get the second stage to a trajectory where it can do it's thing in turn. SpaceX with the Falcon 9 has far more performance and margin on fuel relative to it's empty weight and throw weight. Especially when carrying lighter payloads it has that margin. Electron will always be loaded to basically it's max capacity because anything less just isn't useful.

[steamnut]

On what scale?

Quote: "Rocket Lab does not consider the mission a failure". Surely, if they were trying to catch the booster and didn't, then it most surely is a failure.

[John Brown (no body)]

Re: On what scale?

The overall "mission" succeeded, they recovered the 1st stage. But the Plan A recovery method failed so they used Plan B, which did succeed :-)

[Stuart Castle]

Re: On what scale?

Also, no doubt they'll have useful data from the mission that might help them avoid problems in the future.

[Pascal Monett]

Then why don't they just stick with Plan B ?

This helicopter nonsense was stupid from the start and is starting to look like just an enormous waste of resources - with additional risk to the helicopter crew.

[Mark 85]

I wonder about the logic/wisdom in this also. Seems the mass and speed would create a lot of problemss. Add to that there's a giant eggbeater over top of the chopper. SpaceX had problems getting the things to land on a bouncing ship.

I would think that maybe a deceleration burn that drops the fall speed to near zilch would be a key thing but then, if that were done, just set it down on a barg.

As a former aircrew on a chopper, you couldn't pay me enough to try to catch a falling rocket.

[John Brown (no body)]

No extra rocket burns, it's hanging from parachutes when they try to catch it so falling fairly slowly. It still sounds bum clenching though.

[Excused Boots]

I believe the issue is that salt water is quite corrosive, to some of the materials used in rocket engines and that even if you can recover the booster reasonably intact, it needs a lot more checking and refurbishment than required if it can be recovered 'dry'.

In then meantime

Catch a falling star and put it in your pocket

Never let it fade away

Catch a falling star and put it in your pocket

Save it for a rainy day....

https://www.youtube.com/watch?v=j8CkL3VzU2U

[Anonymous Coward]

Re: On what scale?

The mission was to get a satellite into orbit. Everything else is ancillary. Retrieving a booster dry counts as a 'nice to have', but retrieving it from the sea is acceptable. Not retrieving it at all would also be acceptable (as far as they're concerned), but less so.

As long as the satellite is in orbit, the mission succeeded.

[Potemkine!]

Re: On what scale?

With a secondary point: it must be also economically viable. For this, is recovering boosters a must-have?

== Bring us Dabbsy back! ==

[imanidiot]

Re: On what scale?

The actual mission is launching the payload. That went off without a hitch. Catching the first stage was only a very minor part of said mission and it failing to snatch the rocket in mid-air doesn't make the overal mission a failure. Since the payload went to space.

[Simon Rockman]

Why don't they put retractable wings on the booster and then they could glide them back

[RichardBarrell]

Weight, stability, complexity. The parachute is pretty light and a relatively simple machine.

[hammarbtyp]

Why not just launch the Helicopter

[Charlie Clark]

You mean completely reengineer its aerodynamics and centre of gravity? Nothing simpler…

[Anonymous Coward]

You here that swishing noise above you?

It is the sound of a joke going over your head

[J. Cook]

... So that's not the sound the black helicopters make??

[imanidiot]

People here laugh, but for larger boosters it's not a terrible idea and not the first time it's been proposed. Especially Russian rocket engineers were rather keen on the idea and it surfaced several times

As a booster for the follow up to the soviet space shuttle Energia booster (Urgan/Energia II)

https://www.reddit.com/r/WeirdWings/comments/b3oyd7/the_zenit_flyback_booster_a_fully_reusable_rocket/

More recently proposed as a booster to the new Russian Angara rocket:

http://www.russianspaceweb.com/baikal.html

A video with some more info and pictures:

https://www.youtube.com/watch?v=QVNIaC10MDg&t=360s

[Mark 85]

Would be a bit of snap back atter the bungee is fully stretched. I like that idea though.

[Pirate Dave]

Or build a space-port in LEO that rockets can aim for and dock at while they await a ferry to take them back to terra firma. Seems like - with as many rockets as we hear about wanting to be sent up these days - it would be worth the investment in engineering in materials.

[Howard Sway]

catching it is another matter

Actually, it's straightforward. The key is to fly the helicopter upside down.

[spireite]

Re: catching it is another matter

There's an idea - catch it with a hover craft...

[Fr. Ted Crilly]

Re: catching it is another matter

Ah, but first it would need a full load of eels you see...

[Eclectic Man]

Re: catching it is another matter

I was once told the Russian for "my hydroplane is full of eels", strangely I have never had the opportunity to use it in polite conversation.

[lidgaca-2]

Are helicopters really the best solution for this ?

I would have thought a C-130 fitted with one of those 'catcher' rigs that the US developed for bringing people up from the ground would be a better fit. The C-130 would be a lot faster and so capable of getting into position easier, and provided the parachute cable is long enough, altitude selection by the pickup machine should be less critical.

But I'm not a rocket scientist :(

-- Chris

[Stuart Castle]

I'm not a rocket scientist either, but I suspect the advantage of a helicopter is it can hover near where the rocket is expected to be, then quickly fly in when it's the right time to catch the rocket. C-130s tend not to be able to hover. They could probably circle the place, until the right time, but that's adding more variables to the situation, which may not be good.

[Yet Another Anonymous coward]

Landing the C130 with a rocket dangling on a string underneath is probably trickier

[imanidiot]

Probably not. The Corona program catching returning film capsules from spy sats needed the cargo aircraft (They also used C-119s, C-123s and some other aircraft beside Hercs iirc) with longer loiter times because their target was in a larger area of uncertainty and tracking tech wasn't as advanced. The target was also usually a lot further out to sea. The program for retrieving people/spies from the ground similarly had a fairly large range requirement, plus the added speed was welcome if having to penetrate behind enemy lines. Rocket Lab has a pretty good idea of where their target will be and it's a lot closer to shore. On top of that the aircraft used in the US programs had all sorts of additional equipment to then haul the retrieved cargo into the back of the aircraft. That simply won't work for the much more voluminous first stage of Rocket Lab and it's kinda hard to land an aircraft with such a payload trailing on a cable behind it without damaging said payload.

[imanidiot]

addendum as I was too slow to edit the post:

a C130 is also hellishly expensive to operate. Those 4 (fairly old design) turboprops are rather thirsty. There's few civilian operators of Hercs around (either C-130 or L-100 versions) and most of those are for hauling heavy freight or doing stuff like firebombing.

[stiine]

They also used to catch Firebee drones under C-130's in southeast Asia, the difference being they was much smaller than the C-130.

[EarthDog]

take it to a soft landing area and then let the parachute do the rest.

[Anonymous Coward]

Rube Goldberg plan yields Rube Goldberg level reliablility.

Color me surprised. They missed. One quick point by the way, while the helicopter may be loitering, it probably wouldn't be hovering, as it is actually hard to do, wastes fuel, and doesn't accomplish much.

Helicopters can be handled with a surprising degree of grace by extremely good pilots, and generally under near ideal conditions. Neither of that recommends it as rocket capture strategy. Fixed wing craft were used in some of the previous aerial capture attempts, probably because they had longer range and could operate reliably across a broader range of weather. The payloads were smaller, and much more conducive to stresses of capture.

I suspect that the helicopter was chosen to reduce the air speed at capture and the stress on the device, as well as make lowering it to the ground straightforward, as opposed to having to figure out how to winch the thing in and secure it.

That said, setting down a rocket in hover in your own prop wash doesn't sound like it's going to be a party even if you manage to catch it.

This was always a wacky idea, and I suspect it has become a cover while they try to develop similar technology to the other reusable players in the market today. But a few more half hearted attempts over the next few years and plenty of "conditions were worse then projected" can keep the optimists in tow for a while.

But the economics are not in their favor, as their competition can lift more, cheaper, with faster turnaround, and potentially under broader landing conditions. Their play was that the others would fail trying to tail land. It was a good gamblers bet, that the other players would bust, and that Rocket Lab would be left against the dealer. As it turns out, the other players pulled the right cards, and each is now left with a stronger hand.

Rocket lab already lost this round. If they have enough cash, they can try another hand, but the stakes to stay at the table are going up.

[imanidiot]

Re: Rube Goldberg plan yields Rube Goldberg level reliablility.

Rocket Lab is in an entirely different market from SpaceX. They can carry less, but on a dedicated launcher, which makes getting your payload in a particular orbit might well be worth the added cost to a lot of customers over waiting for a spot on a rideshare going more or less the right direction. Paying for a full SpaceX Falcon 9 is overkill for any payload Rocket Labs is going to be carrying on the Electron (or even on their in development Neutron)

[Eclectic Man]

Landing speed

The landing speed of a C-130 is between 100 and 150 knots. In order to land safely with the rocket intact it would have to be loaded into the cargo bay during the flight (as 'imanidiot' has posted above). The Sikorsky helicopter, otoh can hover and gently lower the recovered rocket into a waiting cradle.

[spireite]

Re: Landing speed

"I'm a mechanic, not a rocket scientist"

[Yet Another Anonymous coward]

>like an Osprey

At which point you have, as they say, 2 problems

[MOH]

Use a biplane, not a helicopter

I can't help feeling the whole problem is either the choice of vehicle or pilots lacking the relevant experience.

If you want to catch something in the air, you don't need a helicopter, you need a biplane and a net. And Dastardly and Muttley.

[Yet Another Anonymous coward]

Re: Use a biplane, not a helicopter

IIRC their success rate was similar to W. Coyote's plans

[fidodogbreath]

fair enough, given that the Sikorsky crew clearly need to be very confident they know the rocket isn't going to whack them out of the sky

Classic Reg understatement.

[WereWoof]

Catch a falling rocket

Catch a falling rocket, with a helicopter

Never let it get away . . . .

With apologies to Perry Como

[TheRealRoland]

Had to scroll way too far down for this...

@imanidiot - "Probably not. The Corona program catching returning film capsules from spy sats needed the cargo aircraft (They also used C-119s, C-123s and some other aircraft beside Hercs iirc) "

Some nice reading material - https://www.nro.gov/Portals/65/documents/history/csnr/corona/StarCatchersWeb.pdf

The National Museum of the US Airforce in Dayton, OH has a nice exhibit about this as well.

[Spherical Cow]

There was no problem with catching the rocket. The rocket's telemetry glitched so they didn't know exactly where it was, and they decided not to try catching it. I have high hopes for the next one.