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[LC0112G]

I would argue that if it cannot glide then it cannot technically fly.

Everything glides. It's just a matter of mind over gravity. One of Kevins Basla Wood and plastic deathtraps might be > 70:1, a 767 is supposedly 12:1, and the Space Shuttle was 4.5:1. F-16's - the original electric jet - can glide here's a vid of one doing a forced landing after an engine failure https://www.youtube.com/watch?v=Puia_yQxir8

I'll concede that the better your glide ratio, the more choice of accident sites you will have, but everything glides.

[Kevin Wood]

I would argue that if it cannot glide then it cannot technically fly.

Everything glides. It's just a matter of mind over gravity. One of Kevins Basla Wood and plastic deathtraps might be > 70:1, a 767 is supposedly 12:1, and the Space Shuttle was 4.5:1. F-16's - the original electric jet - can glide here's a vid of one doing a forced landing after an engine failure https://www.youtube.com/watch?v=Puia_yQxir8

I'll concede that the better your glide ratio, the more choice of accident sites you will have, but everything glides.

Engine failure at 9,000", 7 miles out? I'd be up all afternoon from that height.

[Migv6 le Frog Fan]

Aeroplanes are to be avoided when possible. it just aint natural. My old Mum used to say "if the good lord intended us to fly he would have given us wings instead of arms".
She also said, if the good lord wanted us to smoke he would have put a chimney on top of our heads.
And as a convinced creationist, her answer to Darwinists theory that we came from apes was "If your father is up a tree, mines up in heaven".  Theres no arguing with that. 

[Rods2]

How well it will glide is a function of wing area, wing chord, speed and stall speed, altitude, angle-of-attack, drag and weight.

[78bex]

I get it, so if the air your flying in is rising faster then you are gliding downwards; up you go 

I watched a bloke dressed up like Batman hurl himself off the west slope of Butser the other year.

OK he didn`t just rely on the Bat cape he also had a para -vain parachute thingy 
I was surprised that he didn`t get blown immediately backwards in the stiff south-westerly breeze.
All the model glider pilots present agreed, it was only a matter of time; he sort of went out of view.
Then the screaming started, the Batman was firmly stuck in the Hawthorne & his chute was shredded.
 No one could reach him, every time he moved more thorns inched into him.
As the rain started beating down we headed off to the pub.
 
 

[Migv6 le Frog Fan]

 

[Lizzie Zoom]

As I understand it the latest jet fighters cannot actually stay in the air without their computer systems operating.  They are impossible to fly without this electronic input that adjusts the aircraft's trim.

[Bigron]

I saw that programme too, Lizzie. I hope the software isn't by Microsoft - doesn't that thought send you running to Marks and Spencers? 

Ron.

[Doctor Gollum]

As I understand it the latest jet fighters cannot actually stay in the air without their computer systems operating.  They are impossible to fly without this electronic input that adjusts the aircraft's trim.

Hence my point about gliding most fighters have a glide ratio of 1:1 following stores dumping... The F35 doesn't have an official glide ratio due to its non existent unpowered flight performance. To give you an idea of what a 1:1 descent and subsequent landing feels like, the Osprey has been designed to fragment in order to absorb the impact... basically the props splinter and the wings snap off at the roots whilst the undercarriage/seats/and fuselage all deform to absorb the worst of the impact... the safety cell is tested to deform to 85% of its original volume  with one engine its glide ratio improves to 4:1, so the passengers and crew might walk out of it

By comparison, commercial aircraft seem to fare better, the obvious case being: https://en.m.wikipedia.org/wiki/Air_Transat_Flight_236 

Although it is not an unique situation: https://en.m.wikipedia.org/wiki/List_of_airline_flights_that_required_gliding

Most of the fatal flights in the list are either ones that encounter engine failure either just after take off or during final approach. The notable absence from the list is: https://en.m.wikipedia.org/wiki/British_Airways_Flight_38

Wing/aircraft design, altitude and training are the three equal factors that determine how successfully a powered aircraft might land with no thrust.

[Lizzie Zoom]

I saw that programme too, Lizzie. I hope the software isn't by Microsoft - doesn't that thought send you running to Marks and Spencers? 

Ron.

 

It is a shame Ron that I will never have to worry about that as no one will let me near a jet fighter, let alone the latest models!

As I understand it, aircraft technology in the military field has reached the point where the next generation of jet fighters cannot be manned; no human will be able to withstand the extreme G's when these new beasts are in fight mode.

[Entwood]

As I understand it the latest jet fighters cannot actually stay in the air without their computer systems operating.  They are impossible to fly without this electronic input that adjusts the aircraft's trim.

True.

Partly due to deliberate design parameters.

If an aircraft can fly "hands off" the controls it is by nature an inherently stable design, Kev's gliders are all VERY stable machines, also by design. It takes a deliberate force, and a certain amount of energy to overcome the stability and actually get the aircraft to change direction. This causes problems for an aircraft like a fighter, which actually needs extreme agility in order to perform/survive.

By designing an inherently unstable aircraft it is able to change direction extremely quickly, the more unstable the faster it can change direction, and so becomes "agile" in a way, unfortunately, a human pilot would be unable to control an extremely unstable aircraft as the reaction time/concentration levels would be too extreme.

So, lets make an unstable aircraft that is "controlled" every millisecond by a computor putting in numerous inputs to maintain straight and level flight, and that then "interprets" the pilots inputs to change direction and does one of two things 1) resolves the mathematics for "known" manoeuvres and applies them to the controls to achieve the requirement 2) for "extreme/unknown" manoeuvres  simply allows the inherent instability to express itself then, once the manoeuvre is going in the "right" direction, maintains it, then reasserts stability once the manoeuvre is complete.

This makes an extremely agile, highly sophisticated aircraft that can appear to disobey the laws of nature (watch a high performance jet do a "tail slide" .. where it appears to be flying backwards !! -  and actually is not "flying" at all in the accepted sense of the word!!) but has three serious problems / consideration ... 1) it must be built extremely strongly as the "G" forces involved get very high, 2) without the computor it is, literally, unflyable, 3) the computor, and backups, are not cheap, so the whole aircraft becomes VERY expensive.

[LC0112G]

As I understand it the latest jet fighters cannot actually stay in the air without their computer systems operating.  They are impossible to fly without this electronic input that adjusts the aircraft's trim.

Hence my point about gliding most fighters have a glide ratio of 1:1 following stores dumping... The F35 doesn't have an official glide ratio due to its non existent unpowered flight performance. To give you an idea of what a 1:1 descent and subsequent landing feels like, the Osprey has been designed to fragment in order to absorb the impact... basically the props splinter and the wings snap off at the roots whilst the undercarriage/seats/and fuselage all deform to absorb the worst of the impact... the safety cell is tested to deform to 85% of its original volume  with one engine its glide ratio improves to 4:1, so the passengers and crew might walk out of it

By comparison, commercial aircraft seem to fare better, the obvious case being: https://en.m.wikipedia.org/wiki/Air_Transat_Flight_236 

Although it is not an unique situation: https://en.m.wikipedia.org/wiki/List_of_airline_flights_that_required_gliding

Most of the fatal flights in the list are either ones that encounter engine failure either just after take off or during final approach. The notable absence from the list is: https://en.m.wikipedia.org/wiki/British_Airways_Flight_38

Wing/aircraft design, altitude and training are the three equal factors that determine how successfully a powered aircraft might land with no thrust.

Osprey has two engines and can fly on one. There is a gearbox connecting both sides that allows one engine to power both rotors/propellers. It won't hover though so the landing will be relatively fast and likely quite bumpy. Engine fail in the hover is game over though - and has already lead to several dozen of deaths.

Almost every fighter designed since the mid 70's has been aerodynamically unstable, meaning they needs computers to keep them pointing where the pilot want's them to go. The F-16 I mentioned first flew in 1974 and it has no mechanical connection between the joystick and control surfaces - it's totally fly by wire. Loss of an engine in a multiengine type is serious, but not as bad as loss of an engine in a single engine type - such as F-16 and F-35. However it's not true that they can't glide. As long as there is power for the computers and hydraulics the pilot can control where it goes. The dead stick landing vid shows an F-16 managing a 7 mile approach (37000 feet) from 9000ft altitude - that's a 4:1 glide ratio. Even F-104's have managed dead stick landings - now there's a plane with wing deficiency. Whilst it's true the F-35 doesn't have a published glide rate, it's not going to be much worse than F-16. At present F-35 can't carry external stores so is always going to be 'clean' whereas F-16's almost always have pylons fitted (which can't be jettisoned) and tanks/munitions (which can).

If you sit at the end of a military runway listening to the radio you'll sooner or later get fed up with pilots practicing PFO (Practice Flame Out) or PFL (Practice forced Landing) from Hi and Lo Key.

[Andy H]

An Osprey has just crashed off Australia.

http://www.bbc.co.uk/news/world-australia-40837862

[Rods2]

As I understand it the latest jet fighters cannot actually stay in the air without their computer systems operating.  They are impossible to fly without this electronic input that adjusts the aircraft's trim.

Hence my point about gliding most fighters have a glide ratio of 1:1 following stores dumping... The F35 doesn't have an official glide ratio due to its non existent unpowered flight performance. To give you an idea of what a 1:1 descent and subsequent landing feels like, the Osprey has been designed to fragment in order to absorb the impact... basically the props splinter and the wings snap off at the roots whilst the undercarriage/seats/and fuselage all deform to absorb the worst of the impact... the safety cell is tested to deform to 85% of its original volume  with one engine its glide ratio improves to 4:1, so the passengers and crew might walk out of it

By comparison, commercial aircraft seem to fare better, the obvious case being: https://en.m.wikipedia.org/wiki/Air_Transat_Flight_236 

Although it is not an unique situation: https://en.m.wikipedia.org/wiki/List_of_airline_flights_that_required_gliding

Most of the fatal flights in the list are either ones that encounter engine failure either just after take off or during final approach. The notable absence from the list is: https://en.m.wikipedia.org/wiki/British_Airways_Flight_38

Wing/aircraft design, altitude and training are the three equal factors that determine how successfully a powered aircraft might land with no thrust.

When an aircraft has total engine failure on the final approach the automatic reaction is to pull up the nose, which increases the angle-of-attack and drag, which decreases speed until you stall. Commercial pilots practice dead stick landings as part of their annual flight simulation testing along with other failure stress testing. The pilots of the 747 at Heathrow that lost all engine power due to frozen fuel did very well where their training kicked in and they got it over the parameter fence.

[Doctor Gollum]

As I understand it the latest jet fighters cannot actually stay in the air without their computer systems operating.  They are impossible to fly without this electronic input that adjusts the aircraft's trim.

Hence my point about gliding most fighters have a glide ratio of 1:1 following stores dumping... The F35 doesn't have an official glide ratio due to its non existent unpowered flight performance. To give you an idea of what a 1:1 descent and subsequent landing feels like, the Osprey has been designed to fragment in order to absorb the impact... basically the props splinter and the wings snap off at the roots whilst the undercarriage/seats/and fuselage all deform to absorb the worst of the impact... the safety cell is tested to deform to 85% of its original volume  with one engine its glide ratio improves to 4:1, so the passengers and crew might walk out of it

By comparison, commercial aircraft seem to fare better, the obvious case being: https://en.m.wikipedia.org/wiki/Air_Transat_Flight_236 

Although it is not an unique situation: https://en.m.wikipedia.org/wiki/List_of_airline_flights_that_required_gliding

Most of the fatal flights in the list are either ones that encounter engine failure either just after take off or during final approach. The notable absence from the list is: https://en.m.wikipedia.org/wiki/British_Airways_Flight_38

Wing/aircraft design, altitude and training are the three equal factors that determine how successfully a powered aircraft might land with no thrust.

When an aircraft has total engine failure on the final approach the automatic reaction is to pull up the nose, which increases the angle-of-attack and drag, which decreases speed until you stall. Commercial pilots practice dead stick landings as part of their annual flight simulation testing along with other failure stress testing. The pilots of the 777 at Heathrow that lost all engine power due to frozen fuel did very well where their training kicked in and they got it over the parameter fence.

Fixed