What if? Strap-on VTOL kits

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riggerrob

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What if some one developed a strap-on VTOL kit for airplanes.
This question was s motivated by the recurring rumours of VTOL replacements for all the C-130 military transports currently in service.
VTOL is so heavy and expensive that it detracts from range. You do not a thrust-to-weight ratio greater than 1 to 1 for long range cruise.
So what if we speculate about a strap-on VTOL kit for existing ca go airplanes.
Can it be as simple as solid-fuel JATO bottles?
How do we control roll, pitch and yaw in the hover?
Can we drop all the excess weight a minute or two after take-off?
How many minutes does it need to “burn?”
 
These already exist for small UAVs. Basically fit a boom/pylon onto each which with multiple rotors and electric motors. Some have folding rotors to lower drag in cruise.
 
Rule of cool said:
There are ways to blast regular planes off the ground, getting them back down vertically is another matter entirely.
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I think with modern advances in drone technology it may be doable. Imagine essentially a big tiltrotor/tiltjet drone, that have docking equipment for aircraft below it. During takeoff, drone lift the aircraft vertically, accelerate to flight velocity, and release it. During landing, drone took off, accelerate on straight course, aircraft approach drone from rear and dock with it from below, and then drone decelerate and land aircraft vertically.

May not be easy to work out all bugs, but most likely with modern control systems it would not be much harder than aerial refueling.
 
riggerrob said:
So what if we speculate about a strap-on VTOL kit for existing ca go airplanes.
Can it be as simple as solid-fuel JATO bottles?
Click to expand...
Launching the plane with JATO boosters is simple. Landing is the problem. Aircraft that could only took off vertically but require a full-scale landing strip isn't that much better than just conventional aircraft. The trick is to not only took off but also land vertically.
 
I remember a patent showing a vertical take-off platform equipped with several jet engines, lifting a F/A-18 Hornet.
I must have saved it on my laptop, I will check when back home.
 
In principle vertical landing is pretty easy. Just have your airplane dock with an airship, which will then deposit it gently on the ground.

As has been pointed out, vertical take off is easier still, just add thrust.
 
Dilandu said:
Launching the plane with JATO boosters is simple. Landing is the problem. Aircraft that could only took off vertically but require a full-scale landing strip isn't that much better than just conventional aircraft. The trick is to not only took off but also land vertically.
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I would argue that the optimal version of that is vertical landing and normal rolling takeoff. But for military use you'd really want something that is ESTOL capable: 1000ft or less takeoff roll when fully loaded.

Charlesferdinand said:
In principle vertical landing is pretty easy. Just have your airplane dock with an airship, which will then deposit it gently on the ground.

As has been pointed out, vertical take off is easier still, just add thrust.
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The problem is how heavy those engines are. For example, a C-130 has a Max Takeoff Weight of 155,000lbs. Vertical takeoff means that you need 155,000lbs of thrust, which is 5-6x CFM56 engines.
 
Scott Kenny said:
The problem is how heavy those engines are. For example, a C-130 has a Max Takeoff Weight of 155,000lbs. Vertical takeoff means that you need 155,000lbs of thrust, which is 5-6x CFM56 engines.
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That is why I said 'in principle'. Once you start putting it in practice, you bump into all kinds of engineering challenges.
 
Manuducati said:
I remember a patent showing a vertical take-off platform equipped with several jet engines, lifting a F/A-18 Hornet.
I must have saved it on my laptop, I will check when back home.
Click to expand...

Found it!

US4678141A - Aircraft launcher and retriever - Google Patents

A composite VTOL vehicle comprising a VTOL carrier with outboard mounted engines and an aircraft which is lifted off and retrieved by the carrier.
patents.google.com

As well as a second one (patent numbers on the pictures).
 

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The Shorts jet-lift platform was unfortunately 60 years ahead of the development of autonomous UAV technology that would make it practical

Now a pilot could summon the platform over datalink and arrange an RV.
 
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The only real use for vstol aircraft is on small carriers at sea. Land based aircraft both civil and military need so much support and infrastructure on the ground that a runway is rarely a problem.
F35 has solved the combat jet issue but a vstol AEW aircraft might benefit from clip ons.
 
uk 75 said:
The only real use for vstol aircraft is on small carriers at sea. Land based aircraft both civil and military need so much support and infrastructure on the ground that a runway is rarely a problem.
F35 has solved the combat jet issue but a vstol AEW aircraft might benefit from clip ons.
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Nah, just stick the Wedgetail radar on top of a V-22 and call it done.
 
uk 75 said:
The only real use for vstol aircraft is on small carriers at sea. Land based aircraft both civil and military need so much support and infrastructure on the ground that a runway is rarely a problem.
F35 has solved the combat jet issue but a vstol AEW aircraft might benefit from clip ons.
Click to expand...
I was thinking more along the lines and f the failed “Eagle Claw” raid to rescue American embassy staff being held hostage in Tehran during April 1980.
An HM-13 ground crew member told me that a mysterious group of American aircrew showed up one day to take over their fleet of Simorsky CH-53 Sea Stallion helicopters. Their inexperience was revealed by silly little slips like leaving a flack vest where it interfered with cooling on some
electrical box in the cabin … at least that was the cover story for the failed
raid.
An alternate plan had them landing a C-130 in a soccer field in Tehran. Hah!
 
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Pioneer said:
More realistically, a derivative of the with the Ereye system, would work better.
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Maybe so, I haven't seen the actual weight of the full Wedgetail radar plus operator stations.

But the V-22 can carry 10 tons of stuff.
 

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Scott Kenny said:
Maybe so, I haven't seen the actual weight of the full Wedgetail radar plus operator stations.

But the V-22 can carry 10 tons of stuff.
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Fitting the Wedgetail radar on top of a V-22 might be feasible, but all the associated systems of the radar, computer console/work stations and specialist operators onboard that V-22 will undoubtedly exceed that 10ton and then some.

Regards
Pioneer
 
If you only cared about vertical takeoff, you could simply use a gas balloon to lift you a few hundred feet in the air before applying full power, releasing the balloon and flying away.
This might even be possible in an airplane-dropped kit (ala. Robert Fulton’s Skyhook Extraction system). Just drop it beside the C-130 that landed in a swamp by mistake.

OTOH a balloon might work for vertical landings, but you would need plenty of altitude and a series of drogues to slow the airplane enough that it would not shred the balloon when inflated.
Would you keep propellers turning to help steer to the finally landing spot?
 
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