Author Topic: Hovercraft ADS  (Read 2670 times)

Offline Rocket Science

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Hovercraft ADS
« on: 02/04/2017 05:06 PM »
After thinking about the talk and complexity of trying to flyback the landed booster from a drone ship to speed up processing my thoughts led to a faster drone ship with ability for higher sea states similar to a LCAC...
http://www.militaryfactory.com/ships/detail.asp?ship_id=LCAC-Landing-Craft-Air-Cushion
« Last Edit: 02/04/2017 05:21 PM by Rocket Science »
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Offline Robotbeat

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Re: Hovercraft ADS
« Reply #1 on: 02/04/2017 05:55 PM »
Could be used on land, too! Drive outright up to the HIF or, later on with the BFS, right up to the launch pad.
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Offline laszlo

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Re: Hovercraft ADS
« Reply #2 on: 02/04/2017 06:10 PM »
Not sure how safe or practical a boat with a 44-meter high, 4-meter diameter mast in a 40-kt gale force wind would be.


Offline Robotbeat

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Re: Hovercraft ADS
« Reply #3 on: 02/04/2017 06:11 PM »
Could still be autonomous. :D
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Offline grakenverb

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Re: Hovercraft ADS
« Reply #4 on: 02/04/2017 06:20 PM »


Not sure how practical it would be for landing rockets on, but definitely an awesome vehicle!

Offline Rocket Science

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Re: Hovercraft ADS
« Reply #5 on: 02/04/2017 06:22 PM »
Could be used on land, too! Drive outright up to the HIF or, later on with the BFS, right up to the launch pad.
You reading my mind again?? :o ;D
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Offline kch

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Re: Hovercraft ADS
« Reply #6 on: 02/04/2017 06:54 PM »
Don't forget to evict the eels first ... ;D

Offline Rocket Science

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Re: Hovercraft ADS
« Reply #7 on: 02/04/2017 08:24 PM »
Don't forget to evict the eels first ... ;D
Those would be for lunch for those inclined... ;D
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Offline IRobot

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Re: Hovercraft ADS
« Reply #8 on: 02/04/2017 10:42 PM »
...my thoughts led to a faster drone ship with ability for higher sea states similar to a LCAC...

Unsure if an hovercraft can handle high waves. For some reason (not only fuel saving), you don't see long range hovercraft. I would expect that the very high center of gravity would make them crap with big waves.

Checking "Sea State" classification, the largest hovercraft in the world (Zubr-class) can only handle a sea state of 4.
https://en.wikipedia.org/wiki/Sea_state

That means only up to 2.5 meters, which is kind of pathetic compared to the barges. Even my small 25ft sailboat can handle more than that.


The other problem is that the largest hovercraft is too small, you would need to develop the largest hovercraft ever, that would not be cheap.
« Last Edit: 02/04/2017 10:42 PM by IRobot »

Offline rpapo

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Re: Hovercraft ASDS
« Reply #9 on: 02/04/2017 10:52 PM »
Hovercraft are built more like aircraft, not like ships, because they are held off the ground/water by a cushion of air maintained by high volume low pressure fans.  One very big advantage the current ASDS has as a landing platform is that it is very big and very heavy, a feature not compatible with aircraft-style design.
« Last Edit: 02/04/2017 10:53 PM by rpapo »
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Offline Rocket Science

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Re: Hovercraft ADS
« Reply #10 on: 02/04/2017 11:00 PM »
...my thoughts led to a faster drone ship with ability for higher sea states similar to a LCAC...

Unsure if an hovercraft can handle high waves. For some reason (not only fuel saving), you don't see long range hovercraft. I would expect that the very high center of gravity would make them crap with big waves.

Checking "Sea State" classification, the largest hovercraft in the world (Zubr-class) can only handle a sea state of 4.
https://en.wikipedia.org/wiki/Sea_state

That means only up to 2.5 meters, which is kind of pathetic compared to the barges. Even my small 25ft sailboat can handle more than that.


The other problem is that the largest hovercraft is too small, you would need to develop the largest hovercraft ever, that would not be cheap.
Yes all good points to consider and I was thinking of one of their ADS modified into one or one constructed out of aluminum for a similar landing pad deck area. Just as a side note you can buy LCAC  surplus or even better two mated together... But they want them destroyed... :(

« Last Edit: 02/04/2017 11:02 PM by Rocket Science »
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Online meekGee

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Re: Hovercraft ADS
« Reply #11 on: 02/04/2017 11:25 PM »
A hydrofoil can be a better choice.

It reverts back to a normal barge during landing, but can scurry back fast once done.

Of course what am I saying, an F9 can land on a moving hydrofoil, it's just a matter of some software and active homing - I mean - Apollo already docked with Skylab at 8 km/sec, and that's like 1000 times faster than a hydrofoil.

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Offline Rocket Science

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Re: Hovercraft ADS
« Reply #12 on: 02/04/2017 11:35 PM »
A hydrofoil can be a better choice.

It reverts back to a normal barge during landing, but can scurry back fast once done.

Of course what am I saying, an F9 can land on a moving hydrofoil, it's just a matter of some software and active homing - I mean - Apollo already docked with Skylab at 8 km/sec, and that's like 1000 times faster than a hydrofoil.
It's all relative... ;) ;D
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Offline Robotbeat

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Re: Hovercraft ASDS
« Reply #13 on: 02/05/2017 12:07 AM »
Hovercraft are built more like aircraft, not like ships, because they are held off the ground/water by a cushion of air maintained by high volume low pressure fans.  One very big advantage the current ASDS has as a landing platform is that it is very big and very heavy, a feature not compatible with aircraft-style design.
The largest hovercraft is very large, 550tons fully loaded. And very ship-like.

Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

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Offline Rocket Science

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Re: Hovercraft ADS
« Reply #14 on: 02/05/2017 12:35 AM »
I like this one out Chris B's way... :)

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Offline IRobot

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Re: Hovercraft ADS
« Reply #15 on: 02/05/2017 06:36 AM »
A hydrofoil can be a better choice.

It reverts back to a normal barge during landing, but can scurry back fast once done.
It cannot handle high seas in hydrofoil mode, so the advantage is none.

Of course what am I saying, an F9 can land on a moving hydrofoil, it's just a matter of some software and active homing - I mean - Apollo already docked with Skylab at 8 km/sec, and that's like 1000 times faster than a hydrofoil.
Very misleading analogy. In-space docking is all about relative speeds between spacecrafts, not between spacecrafts and ground. They only move a few cm per second relative to each other, with no outside disturbance.

F9 landing is more complicated by several orders of magnitude. As an example, in-space docking can be done manually, but landing the F9 cannot.

Offline RobLynn

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Re: Hovercraft ADS
« Reply #16 on: 02/05/2017 07:06 AM »
A hydrofoil can be a better choice.

It reverts back to a normal barge during landing, but can scurry back fast once done.
It cannot handle high seas in hydrofoil mode, so the advantage is none.
[/quote]

That is a design choice.  There is nothing preventing a hydrofoil from using deeper foils for less sensitivity to waves (except for a desire to operate in shallow water). Particularly on such a large platform.  But a swathe (small water-line area twin-hull, a catamaran with submerged pontoons and small struts supporting the platform) would probably be a better choice for a large platform with reduced wave sensitivity and good speed through the water with low propulsive power.
I'm a "glass is twice as big as it needs to be" kinda guy

Offline rpapo

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Re: Hovercraft ASDS
« Reply #17 on: 02/05/2017 08:57 AM »
Hovercraft are built more like aircraft, not like ships, because they are held off the ground/water by a cushion of air maintained by high volume low pressure fans.  One very big advantage the current ASDS has as a landing platform is that it is very big and very heavy, a feature not compatible with aircraft-style design.
The largest hovercraft is very large, 550tons fully loaded. And very ship-like.
That's true, but compared to a ship of the same size, a hovercraft is very light.  A Boeing 747 is very heavy, but compared to other vehicles of similar size, very light.

If the ABS/EutelSat "hard landing" of June 15, 2016 had taken place on a hovercraft or a hydrofoil, either of those two kinds of craft would have been sent to the bottom of the ocean in pieces.
« Last Edit: 02/05/2017 10:14 AM by rpapo »
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Offline Rocket Science

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Re: Hovercraft ADS
« Reply #18 on: 02/05/2017 12:23 PM »
A hydrofoil can be a better choice.

It reverts back to a normal barge during landing, but can scurry back fast once done.
It cannot handle high seas in hydrofoil mode, so the advantage is none.

Of course what am I saying, an F9 can land on a moving hydrofoil, it's just a matter of some software and active homing - I mean - Apollo already docked with Skylab at 8 km/sec, and that's like 1000 times faster than a hydrofoil.
Very misleading analogy. In-space docking is all about relative speeds between spacecrafts, not between spacecrafts and ground. They only move a few cm per second relative to each other, with no outside disturbance.

F9 landing is more complicated by several orders of magnitude. As an example, in-space docking can be done manually, but landing the F9 cannot.
I thought meekGee was making a joke about comparing orbital rendezvous and landing on a moving hydrofoil, hence my "it's all relative (velocity)" retort?? ??? I have an oddball sense of humor... ;D But I'll let him explain if he chooses...
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Offline Hobbes-22

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Re: Hovercraft ADS
« Reply #19 on: 02/05/2017 04:52 PM »
The positioning accuracy of a hovercraft is much worse than that of a barge with a set of thrusters.

Online meekGee

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Re: Hovercraft ADS
« Reply #20 on: 02/05/2017 06:33 PM »
Since this is a la-la thread, why not...

In principle, the rocket can translate as fast as the hydrofoil can move, and so if there's active homing, "it's easy"*

For that matter, the hydrofoil will not tip, tilt, or bob with the waves.

---

Without any of that, if you want to launch really often (to Mars) and you want to maximize fuel use, then land on a stable pontoon barge that's just sitting off shore, straight into a landing/launch cradle, do a partial refuel, and hop back.

----

In the sense that other people around here say "it's easy".
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Online CameronD

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Re: Hovercraft ADS
« Reply #21 on: 02/05/2017 09:42 PM »
Since this is a la-la thread, why not...

Going with that theme.. ;)

IMHO, you'd be better off building an artificial island out there - or a cluster of really large oil platforms connected together, complete with lading pad(s), flyback facilities, helipads and as much crew accommodation as you need to run the entire show.

And by putting it out international waters, you could make it duty-fee and start your own country.



With sufficient thrust, pigs fly just fine - however, this is not necessarily a good idea. It is hard to be sure where they are
going to land, and it could be dangerous sitting under them as they fly overhead.

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