Which way is forward?

[Weaver]

Well,
Let's say that you are flying your P-3 Orion or CP-140 or Atlantique on a ASW mission. The M.A.D. operator spots something on his chart, rather than having to turn the whole aircraft around and letting the sub know above him. Just put it in reverse and go back over the target whilst flying at 150ft, sonorbouys would be released and if it was a threat a harpoon or torpedo released.
Other uses would be bombing-air support of ground troops. Identifying them first before attack, cuts down on blue-on-blue.
In-flight refueling. Tanker can come to you, if you are on bingo fuel. Recon, the possibilities are endless.
And if you had a fighter that could change direction in a dogfight.

The only way you'd get that to work is with a tilt-rotor/tilt-wing design, where the props can be tilted up through about 100 deg so that they can slow the plane down and then fly it backwards like a helicopter. However, the aircraft would still need to be light enough to be supported entirely on it's rotor lift without any assist from the wing, so even it it was the size of a P-3, it would still have much less payload.

By way of example:

The V-22 Osprey has two 6,150 shp engines and can take off  (vertically) at 60,500 lb.

The C-160 Transall has two 6,100 shp engines and can take off (horizontally, with wing lift) at 112,435 lb.

[rickshaw]

Just need someone to crack zero-point energy, and who can break the laws of inertia, and we'll be sorted.

Need?  Need?   Use your imagination!   We should be supporting McColm in his desire to have a maritime patrol aircraft that flies backwards, not discouraging him!   Yes,  I know this way leads to madness but its that special sort of madness we should be supporting!  Throw away those restraints my brothers and sisters!  Break free from the shackles that the mere mundane impose upon you, let your imaginations free, I say!   Let it, excuse the pun, fly!   Forwards, backwards, sideways, up, down, who cares?  It is all inside your minds, you can have things do anything!!!!!*   






*Just remember, don't try this at home for real.  You might get hurt and you'll definitly run up some serious hospital bills quite quickly.   Also, don't tell your ordinary friends, family, passers by in the street or you will be locked up, be given strong medications and find while the world looks more like your imagination, your imagination will now look more like the mundane world.   

[Old Wombat]

Just need someone to crack zero-point energy, and who can break the laws of inertia, and we'll be sorted.

Need?  Need?   Use your imagination!   We should be supporting McColm in his desire to have a maritime patrol aircraft that flies backwards, not discouraging him!   Yes,  I know this way leads to madness but its that special sort of madness we should be supporting!  Throw away those restraints my brothers and sisters!  Break free from the shackles that the mere mundane impose upon you, let your imaginations free, I say!   Let it, excuse the pun, fly!   Forwards, backwards, sideways, up, down, who cares?  It is all inside your minds, you can have things do anything!!!!!*   


*Just remember, don't try this at home for real.  You might get hurt and you'll definitly run up some serious hospital bills quite quickly.   Also, don't tell your ordinary friends, family, passers by in the street or you will be locked up, be given strong medications and find while the world looks more like your imagination, your imagination will now look more like the mundane world.   

Oo-ooh! Scary!

[Weaver]

Well if you want to be like that about it, let's have symetrical section wings and tailplanes that flip though 170 deg to work backwards, with ten PT6As along the LE of each one to provide blown wing effect, and a rapid-deployable helium balloon to make up the missing lift during the middle of the transition phase - simples!

[rickshaw]

Well if you want to be like that about it, let's have symetrical section wings and tailplanes that flip though 170 deg to work backwards, with ten PT6As along the LE of each one to provide blown wing effect, and a rapid-deployable helium balloon to make up the missing lift during the middle of the transition phase - simples!

Now thats more like it!   

[McColm]

Thanks Rickshaw,
My straightjacket restricts my movement and these pills, uppers for when I'm down and downers for when I'm hyper. I should be a mad scientist with my sidekick Igor.

A submarine normally travels at 5-10 knots, some can move much faster and if you have up-to-date charts can reach speeds of 50 knots over submerged mountain ranges. A lot depends on the sea saltiness, temperature and depth.

You don't have to stop a car to put it in reverse and to trim the pitch on a propeller blade you don't stop the engine. You don't stop a plane immediately if you use reverse thrust on the ground either. So why would you need to stop an aircraft in mid flight in order to fly backwards?
The air(liquid) would still be flowing over and under the wing creating lift- the same as an aircraft with forward swept wings or the Northrop 'switchblade' which did/didn't fly back in the early 1990s whose patten was filed.
The only difference would be the disturbance over the wing, likewise with the Osprey the propellers don't stop turning whilst transforming from vertical to horizontal flight or the other way round.
There are stunt planes that appear to hover whilst in flight, they don't stall to change direction.

[Old Wombat]

Ah, an in-flight "hand-brake turn"! (You know the one; the good guys are being chased by the bad guys & the good guy in the passenger seat complains that he can't get a decent shot at the bad guys, so the good guy driving hits the hand brake & spins the car around & ends up driving backwards so the passenger good guy can shoot at the bad guys without having to twist around when he's leaning out the window..... Had a Sgt, when I was in the NT Police who regularly took off from a stop doing the reverse of that).

Interesting!

[Hobbes]

Ah, I see now. Not change the flight path, but change the orientation of the aircraft relative to its flight path, ie not fly nose-first.

There are some Su-27 variants that can do a backflip and end up with the tail pointing in the flight direction, but that's not stable (airspeed drops like a brick and pretty soon the aircraft falls out of the sky).

There was also the Hawker Siddeley concept for an aircraft that had canards set at an angle of 45 degrees (ie pointing down), this would allow it to keep flying while yawed way off its flight axis.

[Rheged]

 I'm told that the Afrika Corps in 1941 were perplexed by aircraft hovering above them and dropping bombs vertically.They may have  assumed that  "Perfidious Albion & Co. Ltd"   had secretly developed an attack helicopter. Actually, it was Fairey Swordfish flying against a high wind and  making no progress at all.  They had an  indicated airspeed of about 40 knots and a groundspeed of minus 5 knots!    I would imagine that a Storch could be made to behave the same way.

[PR19_Kit]

There's also the not inconsiderable problem of the poor crew members! 

If the aircraft came to a rapid halt in mid-air and then trucked off in reverse they would be subjected to MASSIVE G loads to say the least. Better to think of this being a UAV with a data link to a ground station where the 'crew' can sit in their lounge chairs and drink coffee while 'on patrol' perhaps?

[tigercat]

What about a Do 18 Wal type aircraft with pusher and tractor airscrews and a symmetrical wing you could just disengage the appropriate airscrew and reverse direction being a flying boat it would be able to float if it plummetted too far and you could mount all the seats on shock absorbers.

[martinbayer]

An aircraft wing will only work in one direction, going forward.  It can fly upside down but still going forward.  I don't think I've ever heard of an aircraft ""flying"" backwards as the airfoil doesn't work that way (someone is bound to correct me now, that's for sure  )

Kitnut617,

there have at least been concepts and attempts to create rotorcraft that would be able to stop the rotors in flight and use them as lift generating wings, which would require the rotorblade/wing profile to work with the airflow going either way (and/or also at an angle across the lifting surface). Some designs for example by Peter Girard of Ryan can be seen here:

http://www.secretprojects.co.uk/forum/index.php?topic=2774.0

More recent related efforts were the the Sikorsky X-Wing

http://www.secretprojects.co.uk/forum/index.php/topic,117.0.html

and the Boeing Dragonfly

http://en.wikipedia.org/wiki/Boeing_X-50_Dragonfly

Although none of these projects was successful, the problems seem to have been more related to control issues and the challenging transition between operational modes than the bidirectional profiles for reversible flow conditions. And then there is of course the extremely fine piece of sophisticated aeronautical engineering represented by the Caproni-Moroni C2 :

http://discaircraft.greyfalcon.us/Major%20Howdy%20Bixby.htm

Martin

[kitnut617]

You don't have to stop a car to put it in reverse and to trim the pitch on a propeller blade you don't stop the engine. You don't stop a plane immediately if you use reverse thrust on the ground either. So why would you need to stop an aircraft in mid flight in order to fly backwards?

Here's an example which you might understand. Engine pistons go up and down in a cylinder, if it was a 4-stroke and had a stroke of 4" and the max rpm is 10,000 rpm, the speed of the piston travelling up (or down) the cylinder is about 1,666 feet per minute.  But each time the piston gets to the top or bottom of the cylinder it comes to a complete stop (for a split second) and then reverses it's direction even though the crank is going around and around and doesn't stop

What you're suggesting is the same, if you're going forward and then go in reverse, at a small moment in time you will come to a stop before you can change the direction you're going in.  Laws of physics I'm afraid.

[Weaver]

You don't have to stop a car to put it in reverse and to trim the pitch on a propeller blade you don't stop the engine. You don't stop a plane immediately if you use reverse thrust on the ground either. So why would you need to stop an aircraft in mid flight in order to fly backwards?

Actually you do have to "stop" a car to put it in reverse, that is to say, if you start off going forwards at 30 mph, then decelerate 40 mph so that you end up going backwards at 10 mph, there will be a point where your speed is, however fleetingly, zero. It's not the engine's internal combustion that "stops", it's the car's motion.

Now your car doesn't fall off the road if you drive under a certain speed, but aircraft are less fortunate. If you perform the same maneuver in an aircraft with a stalling speed of 90kts, then from the moment your speed drops through  +89kts to the moment it hits -89kts again, your wing is generating ZERO lift, and you will be dropping like a stone. You might get away with this if you're at 30,000 ft, (where aircraft routinely survive stalls), but your example was an MPA at 150ft (where they routinely don't) .

The air(liquid) would still be flowing over and under the wing creating lift- the same as an aircraft with forward swept wings or the Northrop 'switchblade' which did/didn't fly back in the early 1990s whose patten was filed.

.

A forward swept wing still has a normal airfoil section like a conventional one, i.e. with the blunt edge forwards. Airfoils have blunt leading edges and sharp training ones so that air gradually changes direction as it hits the wing and is then smoothed back into the surrounding airflow at the sharp trailing edge. If you fly the wing backwards, then at a very low angle of attack, the airflow over the top of the wing will break away from it and become turbulent, due to the sharp "leading" edge, and you get a stall much earlier than you would with a blunt leading edge.

You probably can design symetrical airfoils with variable incidence that work either way, but I suspect they'd be a highly unsatisfactory compromise. The various stopped rotor helo designs depend on blowing air over their rotors from leading edge slots to manage the transition from rotating to stopped, and AFAIK, none of them have actually been made to work in the real world.

The only difference would be the disturbance over the wing, likewise with the Osprey the propellers don't stop turning whilst transforming from vertical to horizontal flight or the other way round

No, but then the Osprey's rotors arn't supporting it by aerodynamic lift, in the same way that it's wing is. In forward flight they're propelling it, and in vertical flight they're supporting it by thrust, in the same way as a helicopter. The point is that vertical thrust generates a lot less lift that you can get by using the same amount of horizontal thrust to push an optimally designed wing through the air, which is why the Osprey's max take off weight is half the Transall's for roughly the same installed power.

There are stunt planes that appear to hover whilst in flight, they don't stall to change direction.

They have so much thrust-weight ratio that they can "hang" from the prop: effectively, they're a "tilt-airframe" design instead of a tilt-rotor or tilt-wing. Again, they penalty is payload: they are essentially "empty toy" planes with a pilot and an engine and little else. If you loaded them down with two people and a weekend's luggage, they'd still take off (just in a longer distance), but they wouldn't hang on the prop.


Must admit, I quite like the idea of a fully loaded P-3 with eight NK-12 Bear engines pulling up to the vertical, hanging on the props and hovering backward over the sub, though. You'd have to:

a) drop the torpedo from a tube parrallel to the MAD boom,

b) remember not to use a nuclear depth charge.

You wouldn't see it in mid-Atlantic though, because it would run out of fuel within sight of Keflavik....

[PR19_Kit]

Must admit, I quite like the idea of a fully loaded P-3 with eight NK-12 Bear engines pulling up to the vertical, hanging on the props and hovering backward over the sub, though. You'd have to:

I like the idea too, but I bet the crews wouldn't!

Of course you could kit them out with those swivel seats that Convair and Lockheed used on the XFY-1 and XFV-1 VTOL aircraft, at least then they'd stand some chance of retaining their breakfast.....