h a l f b a k e r yA hive of inactivity
add, search, annotate, link, view, overview, recent, by name, random
news, help, about, links, report a problem
browse anonymously,
or get an account
and write.
register,
|
|
|
Please log in.
Before you can vote, you need to register.
Please log in or create an account.
|
Ejector seats have saved the lives of many pilots.
However, "banging out" is a far from pleasant experience, and can cause spinal damage.
This is because the pilot must leave the aircraft with substantial vertical velocity to clear the airframe, particularly the tail; thus extreme acceleration
is necessary.
However, a little consideration of relativity leads to a startling conclusion. For a passenger on a train, it is impossible to determine if the train leaves the station, or the station leaves the train.
Thus the answer is not to eject the pilot's seat, but for the seat to reject the aircraft.
In an emergency, the cockpit cover is "blown" in the usual way, but instead of the seat being launched upward on rails, a small charge simply imparts a gentle vertical acceleration to the seat. As the seat starts to rise, very much larger propellant charges mounted at critical locations drive the entire aircraft very fast in the opposite direction, i.e. downwards. After all, if the pilot has been forced to eject, the airframe's a total loss anyway.
So the pilot retains their forward momentum, and rises gently upward, while the aircraft is hurled away from them fast enough that they don't hit any part of it.
BorgCo are currently accepting applications from prospective testers of this amazing new technology, which has the potential to be a great advance in aviation safety, once we iron out one or two very minor problems.
American Airlines Flight 587
https://en.wikipedi...Airlines_Flight_587
"aggressive use of the rudder controls by the co-pilot caused the vertical stabilizer to snap off the plane" ... [8th of 7, Jan 17 2018]
Rudder problems, an industry standard.
https://en.wikipedi...g_737_rudder_issues
[bs0u0155, Jan 17 2018]
[link]
|
| |
This is pretty damned clever, but why not replace the
charges with air foils that pop up to push the plane down?
Getting a 250 pound man / seat combo to pop up doesn't
need a lot of explosive but getting that multi ton plane to
move in the opposite direction would require many times
more explosives. Getting the aircraft to hold
together once you pop these things might make a bad
situation worse. |
|
| |
Might be able to get the plane to nosedive out from under
the pilot with a simple flap on the nose that pops up, both
pushing the plane downwards and affording the ejecting
pilot a temporary wind screen to keep him from getting
blown back into the plane until it gets out of the way. |
|
| |
In faaaact, you could have that flap just pull the pilot and
seat out like a crane. He gets flipped up while the plane
gets pushed down. |
|
| |
You're close, but with enough mattresses already in the cockpit you could just skip the exiting the plane part and just bounce on the mattresses when the plane de-airs. |
|
| |
I like it, aside from the glaring flaw that the seat would
still have its previous momentum making low altitude
ejections impossible. |
|
| |
Not impossible, just fatal. |
|
| |
Don't say that, it puts off potential testers ... it's hard enough to recruit as it is. |
|
| |
//However, a little consideration of relativity leads to a startling conclusion.// |
|
| |
I was really hoping for a consideration of ejection at v/c approaching 1. Your next statement applies only to constant velocity. |
|
| |
These days, survival after ejection from ground level is also considered important. I would recommend that a drilling rig is attached to the aircraft to allow for this situation. |
|
| |
What if you simply blew the vertical tail off the plane,
faster than the pilot was rising? |
|
| |
If so much of the plane needs to be removed before the pilot can eject, perhaps landing it would the more practical option. |
|
| |
This apparently makes complete sense. I wonder if the
autorejection act could cause the plane to go into drone-
mode, flying the damaged remains in ways that a human
passenger would not permit. |
|
| |
Needs brass and mahogany. |
|
| |
In most cases the pilot is free to move on with her life and see
other aircraft, but sometimes the rejected aircraft becomes
fixated and embittered. |
|
| |
If there's anyone who's going to be able to speak about rejection on the basis of a wealth of personal experience, it's you, [IT]. |
|
| |
Life's just full of these little ironies, isn't it ? |
|
| |
I like this idea. I wonder if, to some extent this is already
in use. It would be pretty trivial for example to use
canards and elevons to provide a lot of down force to a
Typhoon for example. |
|
| |
I thought a while ago that a switch to engage a somewhat
attenuated ejection might be desirable. There's a big
difference between loosing all pitch control while lawn
darting at the ground from 1000ft and say, running out of
fuel. In the latter, you could flip the switch, pitch up to
slow and get the vertical stab out of the way and punch
out with a little less violence. |
|
| |
I think though, ejection is one of those places where a
brutal simplicity is preferred. They used to have two
handles for options, but it introduced decision time
between the two. Linking the seat action to the aircraft
in an ejection scenario is asking a known damaged
component to perform. Do you really want additional
electrical dodads in an active electronic warfare
environment or even EMP? |
|
| |
The solution, surely, is either to put the vertical stabiliser at the front, or put the plane into reverse before banging out. |
|
| |
// put the vertical stabiliser at the front, // |
|
| |
Been tried. Didn't end well ... |
|
| |
// put the plane into reverse before banging out. // |
|
| |
Been tried. REALLY didn't end well ... |
|
| |
// It would be pretty trivial for example to use canards and
elevons to provide a lot of down force to a Typhoon for example.
// |
|
| |
Yes, but you counter your own point ... for whatever reason,
you've lost control and the die-by-wire FCS has wandered off into
the tall grass. |
|
| |
But pyrotechnics, linked mechanically (det cord) via multiple
paths to the bang handle, are ultra-reliable. |
|
| |
//But pyrotechnics, linked mechanically (det cord) via
multiple paths to the bang handle, are ultra-reliable.// |
|
| |
So how does this work? If your large charge drives the
front of the airframe down, you may end up with the
aircraft rotating in pitch and the vertical stab moving
forwards in a... stabbing motion. You could drive down
the rear, then the violent pitch-up would drive the seat
into the cockpit, contrary to what you want. Doing both
at once requires two coordinated charges, these would be
HUGE compared to the seat charge and necessarily
distributed around the aircraft. The explosives are
already a huge hazard, more and larger charges multiply
the danger and modes of failure. |
|
| |
I wonder if the charge could extend a telescopic tube
upwards to act as a guide for the seat to follow designed
to miss the vertical stabilizer? Or, deploy a much larger
section, canopy + significant surrounding structure. Just
the mass ratios will drive the airframe down. Getting the
timing right would be tough. |
|
| |
Thinking about this, it seems clear that the pilot will be wearing an ejector seat at the time of egress. It's also clear that his (or, indeed, her) forward speed relative to the airframe will be zero initially. Unless the pilot has left a foot on the throttle, the plane will not be accelerating. Therefore, it is only the relative wind (admittedly, perhaps 500mph) driving the pilot into the vertical stabiliser. |
|
| |
Given a horizontal distance of, say, 6 metres between the cockpit and the tail, the pilot should not be doing more than 40-60mph by the time they hit the tail. So, simply design the ejector seat to be able to withstand a 60mph impact, and/or make the upper leading edge of the vertical stabiliser crumplable. The main aerodynamic forces on the vertical stabiliser must be lateral, so fore-aft crumplability seems feasible. |
|
| |
Not explosives, propellants. H.E. will cause supersonic fragmentation. Think vertically-orientated JATO bottles. |
|
| |
Initiate the pushers at the rear of the airframe slightly before the mid and front, causing it to pivot around the C of G, then "drop". |
|
| |
At the point of separation the aircraft and pilot have the same velocity. Due to mass/area factors, as the pilot hits the slipstream they start to lose velocity due to drag. If the aircraft then accelerates rapidly downwards, the pilot will clear the empennaged without needing too much vertical speed themselves. |
|
| |
// a telescopic tube upwards to act as a guide for the seat to follow // |
|
| |
Semi-baked on the Space Shuttle. |
|
| |
// The main aerodynamic forces on the vertical stabiliser must be lateral, so fore-aft crumplability seems feasible. // |
|
| |
Airbus provide lateral crumplability too - just hit the rudder a bit too hard, and Wheee ! Say bye-bye, tailfin ... |
|
| |
//Given a horizontal distance of, say, 6 metres between the
cockpit and the tail, the pilot should not be doing more than
40-60mph by the time they hit the tail.// |
|
| |
Aero drag at sea level is F=1/2 air density*velocity
squared*drag coefficient*frontal area. I get an initial force
of 29,500N for an acceleration of 266 m/s/s or 27G for
500mph ejection. It's close. That v-squared really gets you,
especially at 600mph. After that the drag goes all squiffy
and trans sonic, not my pay grade. |
|
| |
// not be doing more than 40-60mph // |
|
| |
So, your day has gone seriously pear-shaped, you've had to abandon a rather expensive bit of kit belonging to someone else (probably because unpleasant people are shooting at you with evil intent) that you've signed for and they expect you to bring back, and now your comfy chair has slammed into a big lump of titanium ... |
|
| |
They said I was mad, shooting at a $40m fighter plane with a
revolver. And indeed, it would have been futile but for the large
propellant charges pre-positioned in the airframe ... |
|
| |
Small target, easily protected by a kevlar jacket. Plenty of other big, vulnerable targets to go at ... |
|
| |
//very much larger propellant charges// |
|
| |