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Post by silverdragon on Feb 6, 2017 10:50:55 GMT
So I am starting to feel as though maybe a hovercraft near ground level attempting to use a tilt rotor arrangement to move forward may not really be workable.  But isn't that how the Harrier fighter jet works as it transitions form VTOL to horizontal movement? While it doesn't have tilt rotors, the same thrusters rotate from vertical lift to horizontal thrust. I see no reason why you couldn't use the same type system on a hovercraft. Forget rotors. Just use three small, or even large for that matter, jet engines with moveable thrust deflectors like on the Harrier. You could even design them to provide sideways movement. I would think the design would be rather simple. Mount the three jet engines vertically with a gimbal mounted nozzle on the bottom. You could then point the nozzle in any direction. Just to sort of insert the nightmare of vertical jet flight here. Yes it does, however, on a Harrier, the amount of fuel used for vertical flight is a tank-drainer, and on landing, there is the last six foot, where the jet wash may circulate in on its self, and more or less, when you elect to land, that last six foot is almost irreversible... you land or pick somewhere close to land in a hurry, or pick a soft spot in the scenery?.. The selecting to land and then abort takes a whole lot of fuel to go back up again. This is why many Harrier jets when selecting to land vertically on a ship will come to a hover alongside the ship and then time the landing to coincide with wave movements and just slip sideways and cut thrust at the right time to land. Landing a harrier vertically, you better have fuel where it lands, because there wont be a lot left to get airborne again after the effort of braking from horizontal flight to vertical hover and landing. Take off and the transition from vertical to horizontal flight is the kind of thing a harrier pilot will do only one on a tankful, and then it better have fuel nearby. They have also looked at the issue of carrying ordinance great distance, and a harrier take-off from a short runway such as a ship, even with the ski-ramp, may immediately be an issue of needing an in-flight refuelling because its more efficient to refuel like that than it is to try getting airborne with a full tank. In so much that the amount of ordinance would be effected by the weight of the fuel, and at a certain point, a full tank of fuel on take-off is detrimental to the amount of weight it can carry. On Jet hover, With all the best intentions, getting a "cushion" of air under you to sustain a vertical position "so many" foot from the ground gets harder the closer you get to the ground because of the ground effect of displacing the wash, and with all the computerised ability that may be available at this time, suggesting a hover created on jets at say one foot from the ground is a technical nightmare if you are not to include a cushion "skirt" to prevent escape of that cushion such as existing hovercraft use. This is why the harrier is a flying computer, it is built, and was built, and development onwards, as one of the first unstable aircraft in the skies. The Inverted "V" shape of its wings make it incredibly agile, but almost impossible to fly stably for the human mind alone. With all that computing on board, they let the computer decide "How" to hover, you just have the handbrake collective to say "I want vertical hover", and the aircraft does all the rest. You dont have to know how to do the helicopter bit to be able to fly Harrier, but they do prefer that you do train with Helicopters to understand the basics of flying sideways backwards and forwards?.. there is a LOT in common. If the computer fails, your not ever going to be able to fly it on your own.... It would sort of be trying to balance a brick on an egg over three different directions at the same time whilst trying to fly this helicopter hell in any direction at all. I suspect a hover on jets alone is going to be a technical nightmare. Not impossible, because it has been done already, but they had more than just one apple-mac under the hood?.. This is why they got no further with the flying bedstead that became the harrier, because once at any speed, its easier to fly with wings than it is to sustain a hover. And at any speed, "Ground effect" will force you to fly using wings rather than jet hover anyway, because aerodynamics?.. That last bit is beyond my current knowledge level, but I do understand that flying at speed close to the ground creates some unexpected forces if you dont think aerodynamics. Look at the jet car on MB's, however much you manage to balance the thrust, its going to nosedive suddenly?.. |
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Post by Cybermortis on Feb 6, 2017 12:27:02 GMT
Actually the Harrier design was not unstable, quite the reverse in fact. It was the inherent stability of using four nozzles from one engine that made it a viable design, compared to other VTOL craft being developed during the same period.
Nor did the Harrier require computer controlled systems to fly; remember this is a 1960s designed ground attack aircraft and such technology didn't exist and wasn't part of the specifications.
Modern Harriers do use computer control's, but this is more of an upgrade than a requirement of the basic design. Which could be built and fly without such a thing, unlike the F22 or F117 both of which are totally unflyable without computer assistment.
However while classifyed as VTOL aircraft, and capable of vertical flight, it would be more accurate in practice to call them STOL (Short Take Off and Landing) aircraft. The Harrier isn't capable of vertical flight with a combat load, can only hover for a limited time and when taking off and landing vertically runs the risk of debris being thrown up and sucked into the intakes; Not a major issue on the deck of a carrier, but potentually fatal on land.
Harriers typically angle the nozzles to provide both vertical lift and forward movement on takeoff and landing, rather than attempting just pure lift. This dramatically reduces the length of runway needed compared to conventional aircraft, something quite apparent when you compare the size of the flightdeck of the old British Carriers which were specifically designed for Harriers. With Carriers designed with conventional jets in mind.
The images, or rather drawings, of Harriers operating in vertical mode during combat operations come from the early days of the project. And were basically sales tools to market the design, rather than how they actually land or take off.
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Post by mrfatso on Feb 6, 2017 14:10:56 GMT
Just to add another thought with the proposed deplorable turret, how is in controlled?
Is it a manned turret in which case you are asking a gunner to be left in a situation where he could become overrun without the ability to flee the battlefield like the other crew of the vehicle.
If it is controlled remotely then it may become the victim of Electronic Warfare and jammed by the enemy, worst still if captures they get a lot of your technology in a working order. I know airborne drones are remote controlled but they are largely used by the US, its allies and other powers in asymmetric warfare where the enemy does not posses the capacity to jam the signals in the same way.
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Post by ironhold on Feb 6, 2017 15:51:26 GMT
Just to add another thought with the proposed deplorable turret, how is in controlled? Is it a manned turret in which case you are asking a gunner to be left in a situation where he could become overrun without the ability to flee the battlefield like the other crew of the vehicle. If it is controlled remotely then it may become the victim of Electronic Warfare and jammed by the enemy, worst still if captures they get a lot of your technology in a working order. I know airborne drones are remote controlled but they are largely used by the US, its allies and other powers in asymmetric warfare where the enemy does not posses the capacity to jam the signals in the same way. Manned. Basically, the hovercraft would be able to deploy its own fire support and then collect it upon exiting the field. |
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Post by the light works on Feb 6, 2017 16:05:18 GMT
Just to add another thought with the proposed deplorable turret, how is in controlled? Is it a manned turret in which case you are asking a gunner to be left in a situation where he could become overrun without the ability to flee the battlefield like the other crew of the vehicle. If it is controlled remotely then it may become the victim of Electronic Warfare and jammed by the enemy, worst still if captures they get a lot of your technology in a working order. I know airborne drones are remote controlled but they are largely used by the US, its allies and other powers in asymmetric warfare where the enemy does not posses the capacity to jam the signals in the same way. Manned. Basically, the hovercraft would be able to deploy its own fire support and then collect it upon exiting the field. as far as balance is concerned, you would simply write the narrative that the design of the vehicle was such that the removal of the turret did not negatively affect the balance. it still leaves the question of how the weight difference affects the vehicle, but that could be a design feature - running with the turret, it could be limited to air cushion operation, and when it deploys, it becomes a more agile armed forward observer craft. it does still leave the question of what happens to the gunner if the vehicle gets hit. |
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Post by mrfatso on Feb 6, 2017 16:10:12 GMT
Or has to leave the battlefield rapidly and is unable to retrieve the turret.
It is fine if you presume that you will have time enough, but what happens in a situation where you get the tar kicked out of you?
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Post by the light works on Feb 6, 2017 16:22:29 GMT
Or has to leave the battlefield rapidly and is unable to retrieve the turret. It is fine if you presume that you will have time enough, but what happens in a situation where you get the tar kicked out of you? agreed. theoretically, the vehicle will plant to leave the same way it came in, but as they say, no plan ever survives contact with the enemy. mind you, as I said before, this is your story and your culture, so that may be a cultural norm for them - but it is also an opportunity for story development when things go badly. |
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Post by mrfatso on Feb 6, 2017 17:34:56 GMT
I see this in a similar vien to the British Boulton-Paul Defiant aircraft of WW2. en.m.wikipedia.org/wiki/Boulton_Paul_DefiantA concept that seems like a good idea in the design phase but in actual combat will prove a failure. But that in itself could lead to good story ideas as you say LTW. |
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Post by the light works on Feb 6, 2017 18:13:07 GMT
I see this in a similar vien to the British Boulton-Paul Defiant aircraft of WW2. en.m.wikipedia.org/wiki/Boulton_Paul_DefiantA concept that seems like a good idea in the design phase but in actual combat will prove a failure. But that in itself could lead to good story ideas as you say LTW. the defiant looks like a case of "built to fill a niche that was being removed while the filler was being built" |
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Post by Cybermortis on Feb 6, 2017 18:13:26 GMT
The strength of a hovertank would be its speed and agility, and in this context dropping a static turret as fire support is a really bad idea; The vehicle would have to stop to unload and reload the turret and the need to recover it would dictate the line of retreat.
This is not to say that the ability to deploy the turret as a separate defensive item might not be useful. Certainly it would give you the ability to rapidly create a forward firebase, or strengthen the defenses of an existing base. (In fact if the vehicle had a universal mount onto which different weapon or equipment can fit into. Then all of these might be designed to be unloaded and deployed as stand alone sytems the same way as the main turret. This would give you the ability to set up a full defensive system for a base in a couple of minutes. This would make for a very versatile and adaptable vehicle.) But this isn't a feature that would be useful on an actual battlefield.
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Post by the light works on Feb 6, 2017 18:35:21 GMT
The strength of a hovertank would be its speed and agility, and in this context dropping a static turret as fire support is a really bad idea; The vehicle would have to stop to unload and reload the turret and the need to recover it would dictate the line of retreat. This is not to say that the ability to deploy the turret as a separate defensive item might not be useful. Certainly it would give you the ability to rapidly create a forward firebase, or strengthen the defenses of an existing base. (In fact if the vehicle had a universal mount onto which different weapon or equipment can fit into. Then all of these might be designed to be unloaded and deployed as stand alone sytems the same way as the main turret. This would give you the ability to set up a full defensive system for a base in a couple of minutes. This would make for a very versatile and adaptable vehicle.) But this isn't a feature that would be useful on an actual battlefield. In Drake's universe, the strength of his hovertanks was their ability to ignore terrain issues. one of the angles I see this from is the "why this capability?" question. the issue I came back to (and I say that literally, as I returned to the original question to confirm that it was so) is that the vehicle leaves the base with a speed-of-light, line of sight weapon in the functional position, only to drop it off in a fire support emplacement, replacing it with a standoff weapon, and a set of defensive weapons. to me, that is illogical. in that configuration, the drop turret is not capable of indirect fire, and so needs no forward observer - while the attack vehicle is only carrying primary armaments that could easily be used from a fire support emplacement, with a little modification from heat seeking to "smart" targeting. were I specifying this vehicle, I would want the missile racks to be on the drop turret, and the lasers on the vehicle. |
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Post by mrfatso on Feb 6, 2017 23:11:08 GMT
The strength of a hovertank would be its speed and agility, and in this context dropping a static turret as fire support is a really bad idea; The vehicle would have to stop to unload and reload the turret and the need to recover it would dictate the line of retreat. This is not to say that the ability to deploy the turret as a separate defensive item might not be useful. Certainly it would give you the ability to rapidly create a forward firebase, or strengthen the defenses of an existing base. (In fact if the vehicle had a universal mount onto which different weapon or equipment can fit into. Then all of these might be designed to be unloaded and deployed as stand alone sytems the same way as the main turret. This would give you the ability to set up a full defensive system for a base in a couple of minutes. This would make for a very versatile and adaptable vehicle.) But this isn't a feature that would be useful on an actual battlefield. I think that for rapid deployment of such defences a dedicated cargo craft would be better, with some defensive weapon systems such as antiaircraft. For this this I would take the model of Landcraft Tanks and Landing Ships Tanks. The combat power of the hovercraft with a deplorable turret would be reduced compared to a similar size craft that was dedicated only to a mobile offensive role. |
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Post by Cybermortis on Feb 6, 2017 23:28:33 GMT
I'm thinking in regards a combat vehicle that is designed so that the primary weapon systems can be removed and replaced quickly in the field. In such as case further designing those weapon systems so they could actually be deployed on their own would add versatility to the design.
For example such a design would allow fast moving vehicles to scout out an area, pick a suitable location for a forward firebase, engage and destroy any enemies in the area then set up a defensive perimeter to cover the landing of additional supplies and equipment.
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Post by the light works on Feb 6, 2017 23:36:51 GMT
I'm thinking in regards a combat vehicle that is designed so that the primary weapon systems can be removed and replaced quickly in the field. In such as case further designing those weapon systems so they could actually be deployed on their own would add versatility to the design. For example such a design would allow fast moving vehicles to scout out an area, pick a suitable location for a forward firebase, engage and destroy any enemies in the area then set up a defensive perimeter to cover the landing of additional supplies and equipment. tank groups would do something like that just as they were equipped. I think I would still prefer to have an indirect fire weapon in my drop turret. |
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Post by silverdragon on Feb 9, 2017 9:15:51 GMT
Actually the Harrier design was not unstable, quite the reverse in fact. It was the inherent stability of using four nozzles from one engine that made it a viable design, compared to other VTOL craft being developed during the same period. Nor did the Harrier require computer controlled systems to fly; remember this is a 1960s designed ground attack aircraft and such technology didn't exist and wasn't part of the specifications. Modern Harriers do use computer control's, but this is more of an upgrade than a requirement of the basic design. Which could be built and fly without such a thing, unlike the F22 or F117 both of which are totally unflyable without computer assistment. The early ,model was the Kestrel, the harrier, having extra "Reaction" nozzles in the wingtips and front-back of the fuselage to aid in flight stability and VTOL balancing, and the extra computerization came later, to aid with Engine upgrades and a larger airframe as the marks progressed, from Mk1 onwards, it became a bigger bird. Yes initially it was "easy to fly" when compared to others of the same ilk, but it has developed more and more to make it more unstable and agile in flight. You cant have agile without unstable.I think I said that. They have the ability to VTOL, but prefer to STOL where they can to save fuel.But the have the ability to land even on damaged sabotaged runways, which they have done, and offer potential air support as needed whilst that runway is repaired until the larger stuff can land. They were intended to be used as VTOL, Design changes to include the ski-ramp for Navy and operational need, it was changed to as much STOL as they could manage again to preserve fuel and carry heavier ordinance. And the fact that the two largest users being the two sides of the pond navies... the Harrier was designed with land based Ground attack Recognisances [GAR] in mind, but proved very useful in other theatres, so was sort of posted sideways, which did sort of require a immediate removal of all magnesium parts which corrode quickly in salt air, and integration of American IFF identification systems. Flying one now, with all its extra componants and electronics, is an art form in its self, there is a hell of a lot of extra buttons in there from the initial Mk1 proposals. And some of them you need. The ground based ones are now/were changed from GAR to CAS, Close air support, first, and GER second, but it was quickly noted that any servicing of the engine needed a "Wings off" service, the engine in not easy to get too, so most of my own experience of that exotic bird were of crowds of boiler suits swearing profusely trying to get them back on again "Of course they must fit, they came off easy enough?..." and other such oaths [profanity removed] or of the same boiler suits swearing and moaning about the lacjk of space with "Its easier to change the [redacted] oil filer on a [redacted] mini"... [more redacted] [British leyland Mini] coming from somewhere inside the airframe. During the falklands disagreement, two Container ships were "Modified" to carry Harrier {and other rotor wing aircraft} down that way, once again, use of VTOL proved helpful in that they didnt need taking to pieces and being put into crates to do that. Of course we didnt expect one of those to be attacked and destroyed with its cargo on board, all Chinook's but one were lost. Only two fatalities, one of our Royal prince of the realm was one of the first doing evacuations in the SAR, which sent footage of him around the world. The harrier has evolved in many directions. But it is known as being unforgiving in flight. |
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Post by ironhold on Feb 23, 2017 19:21:27 GMT
Another bit that came to mind recently.
A triangle-shaped helicopter with a rotor at each triangle point.
I'm thinking perhaps that this would be a heavy lift job, such as a modern-day Skycrane, with the three blades offering stability and perhaps even a greater amount of cargo weight for its size, but perhaps at the cost of it being wide.
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Post by the light works on Feb 24, 2017 4:31:40 GMT
Another bit that came to mind recently. A triangle-shaped helicopter with a rotor at each triangle point. I'm thinking perhaps that this would be a heavy lift job, such as a modern-day Skycrane, with the three blades offering stability and perhaps even a greater amount of cargo weight for its size, but perhaps at the cost of it being wide. I think that having an odd number of rotors would result in a torque bias. a quadrotor drone has two rotors turning in each direction so that the torque is balanced. to do a trirotor, you would have to have dual counterrotating rotors at each point, which would be mechanically more complicated. when I think about it, I'm not sure how a drone adjusts rotor speed to rotate, but I would guess it throttles the rotors turning opposite the desired rotation up, and the others down, to induce the torque to turn the drone. edit: there do seem to be trirotor drones on the market, though. this is the easiest manufacturer to find on the internet. I have no connection or experience with them. rcexplorer.se/product/tricopter-v3-kit/ |
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Post by ironhold on Feb 24, 2017 5:41:24 GMT
en.wikipedia.org/wiki/Ford_TransitAnother idea I've been chewing on - See the vehicle at the top of the article? Something like that converted into a caravan (re: mobile home) with minimal exterior modification. The mental image I have in my head is of a small bathroom area (toilet, shower, sink, water reserves) in the rear, a small kitchen area (sink, stove, small refrigerator, microwave, counter space) on the wall opposite the side door, stow-and-go seating and tabletops opposite the side door opening, and front driver & passenger seats that can safely go completely flat. One flat-screen television would be pre-installed on the front center console, while a second would be pre-installed in the small kitchen area; the kitchen one would have a hookup for a game console or a DVD player. The television sets would already be set up to receive broadcast signals from local television stations. Extras would include solar panels, satellite television, and satellite radio. The logic would be that in the universe they'd be used in, they'd be comparatively cheap "starter" models for childless couples or close friends. The trade-off, however, is that users would have to either sleep in the front chairs or sleep on the floor once the seats & tables are stowed (I'm having trouble envisioning how proper bedding could be inserted into a design like this short of futon mats).
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Post by silverdragon on Feb 24, 2017 7:04:01 GMT
en.wikipedia.org/wiki/Ford_TransitAnother idea I've been chewing on - See the vehicle at the top of the article? Something like that converted into a caravan (re: mobile home) with minimal exterior modification. The mental image I have in my head is of a small bathroom area (toilet, shower, sink, water reserves) in the rear, a small kitchen area (sink, stove, small refrigerator, microwave, counter space) on the wall opposite the side door, stow-and-go seating and tabletops opposite the side door opening, and front driver & passenger seats that can safely go completely flat. One flat-screen television would be pre-installed on the front center console, while a second would be pre-installed in the small kitchen area; the kitchen one would have a hookup for a game console or a DVD player. The television sets would already be set up to receive broadcast signals from local television stations. Extras would include solar panels, satellite television, and satellite radio. The logic would be that in the universe they'd be used in, they'd be comparatively cheap "starter" models for childless couples or close friends. The trade-off, however, is that users would have to either sleep in the front chairs or sleep on the floor once the seats & tables are stowed (I'm having trouble envisioning how proper bedding could be inserted into a design like this short of futon mats). Done already.  More similar through this page... duckduckgo.com/?q=ford+transit+mobile+home&t=ffab&atb=v48-5a_&iax=1&ia=imagesThe ford transit has been a popular starter point for mobile home/caravans in UK for many decades. |
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Post by mrfatso on Feb 24, 2017 9:07:38 GMT
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