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V-22 Osprey "ground effect" question



 
 
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  #1  
Old December 28th 06, 02:20 PM posted to rec.aviation.military.naval
Robert[_1_]
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Posts: 5
Default V-22 Osprey "ground effect" question

In the publicity photo's of ship landing's the V-22 looks like one prop is
in "ground effect" and the other one is hanging over the side of the ship so
it's NOT in "ground effect"

Does anyone know how big of a problem this is? Does it limit the cross-wind
performance? So even though it's vtol the ship has to be pointed into the
wind etc?


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  #2  
Old December 28th 06, 06:46 PM posted to rec.aviation.military.naval
Henry J Cobb
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Posts: 42
Default V-22 Osprey "ground effect" question

Robert wrote:
In the publicity photo's of ship landing's the V-22 looks like one prop is
in "ground effect" and the other one is hanging over the side of the ship so
it's NOT in "ground effect"

Does anyone know how big of a problem this is? Does it limit the cross-wind
performance? So even though it's vtol the ship has to be pointed into the
wind etc?


It depends on the ship, but the Osprey has to deal with the same sorts
of problems when hovering over buildings on land.

The trick is that the pitch of the two props isn't fixed to be the same
value so it can adjust for uneven lift.

-HJC
  #3  
Old December 29th 06, 03:03 AM posted to rec.aviation.military.naval
Diamond Jim
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Posts: 23
Default V-22 Osprey "ground effect" question


"Henry J Cobb" wrote in message
...
Robert wrote:
In the publicity photo's of ship landing's the V-22 looks like one prop
is
in "ground effect" and the other one is hanging over the side of the ship
so
it's NOT in "ground effect"

Does anyone know how big of a problem this is? Does it limit the
cross-wind performance? So even though it's vtol the ship has to be
pointed into the wind etc?


It depends on the ship, but the Osprey has to deal with the same sorts of
problems when hovering over buildings on land.

The trick is that the pitch of the two props isn't fixed to be the same
value so it can adjust for uneven lift.

-HJC


Navy Ch-46's deal with this many times a day as they resupply all the ships
in the fleet from the biggest to the smallest. Not a problem.


  #4  
Old December 31st 06, 09:02 PM posted to rec.aviation.military.naval
Erken
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Posts: 2
Default V-22 Osprey "ground effect" question


"Robert" wrote in message ...
In the publicity photo's of ship landing's the V-22 looks like one prop is
in "ground effect" and the other one is hanging over the side of the ship
so
it's NOT in "ground effect"

Does anyone know how big of a problem this is? Does it limit the
cross-wind performance? So even though it's vtol the ship has to be
pointed into the wind etc?


Greetings Robert,

We looked at this pretty hard, on the first sea trials back on the WASP,
many years ago now with the FSD aircraft. As predicted by all the work-ups
to the event(s), it's just a matter of a gentle cyclic input against the
roll, with the rate of the input being proportional to the rate at which
you're crossing the deck edge. The test pilots involved did it without
having to think about it. In hover over the deck, at least in the old FSD
birds, you could expect abut 1/4 inches of stick trim to cancel out the
roll. It does not limit the effective cross-wind performance, as there is
more control margin left even with that little off-set than required for all
rated cross-wind conditions. Every knot of forward ship is a bonus, works
just fine with zero knots ships speed.

But your observation is correct, sticks centered on the deck will produce a
roll-off to the left if not corrected for.

Erk


  #5  
Old January 1st 07, 08:29 PM posted to rec.aviation.military.naval
Don McIntyre
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Posts: 18
Default V-22 Osprey "ground effect" question


Greetings Robert,

We looked at this pretty hard, on the first sea trials back on the WASP,
many years ago now with the FSD aircraft. As predicted by all the work-ups
to the event(s), it's just a matter of a gentle cyclic input against the
roll, with the rate of the input being proportional to the rate at which
you're crossing the deck edge. The test pilots involved did it without
having to think about it. In hover over the deck, at least in the old FSD
birds, you could expect abut 1/4 inches of stick trim to cancel out the
roll. It does not limit the effective cross-wind performance, as there is
more control margin left even with that little off-set than required for all
rated cross-wind conditions. Every knot of forward ship is a bonus, works
just fine with zero knots ships speed.

But your observation is correct, sticks centered on the deck will produce a
roll-off to the left if not corrected for.

Erk


Speaking of V-22 FSD aircraft, I posted some pics of the #3 FSD
aircraft. Photos were taken at the American Helicopter Museum in West
Chester, PA.

http://s20.photobucket.com/albums/b2...0Osprey%20FSD/

Includes exterior and some cockpit detail photos.

Comments welcome.

Don McIntyre
Clarksville, TN

  #6  
Old January 2nd 07, 12:45 AM posted to rec.aviation.military.naval
Erken
external usenet poster
 
Posts: 2
Default V-22 Osprey "ground effect" question: Cockpit stuff


"Don McIntyre" wrote in message
oups.com...

Greetings Robert,

We looked at this pretty hard, on the first sea trials back on the WASP,
many years ago now with the FSD aircraft. As predicted by all the
work-ups
to the event(s), it's just a matter of a gentle cyclic input against the
roll, with the rate of the input being proportional to the rate at which
you're crossing the deck edge. The test pilots involved did it without
having to think about it. In hover over the deck, at least in the old FSD
birds, you could expect abut 1/4 inches of stick trim to cancel out the
roll. It does not limit the effective cross-wind performance, as there is
more control margin left even with that little off-set than required for
all
rated cross-wind conditions. Every knot of forward ship is a bonus, works
just fine with zero knots ships speed.

But your observation is correct, sticks centered on the deck will produce
a
roll-off to the left if not corrected for.

Erk


Speaking of V-22 FSD aircraft, I posted some pics of the #3 FSD
aircraft. Photos were taken at the American Helicopter Museum in West
Chester, PA.

http://s20.photobucket.com/albums/b2...0Osprey%20FSD/

Includes exterior and some cockpit detail photos.

Comments welcome.

Don McIntyre
Clarksville, TN



Brings back a lot of memories, thanks for posting the pictures.

At the risk of droning, I'll point out some of the flight test unique items
are clearly visible in the pictures.

Starting with the picture of center console: The console is pretty different
in the a/c today, one of the most obvious changes are that the two little
screens in the center middle console (Tac/Nav control heads) have been
replaced by a single large display, and the two keysets with a single one
below the screen. The LCD display to the left of the attitude ball was the
only back-up instrumentation in aircraft in the event the displays failed,
along with the attitude ball. This aircraft, 13, I think was the one that
flew back from a test flight with only these instruments working, up at
Philly. Peasly, I think was the pilot on that flight, but that's going back
a long time. On the LCD display itself is a maintenance sticker (round white
dot) probably states that this unit is INOP. To the left of the LCD display
is the flap handle, currently set it 'auto'. It pretty much stayed there
unless you had a malfunction. Auto, 0, 20, 40, Full. Full was 67 degrees,
down, mostly to get out of way of the downwash from the props. The small box
with yellow lights and small knobs mounted on top of the glareshield is the
Flight Test Instrumentation Panel, or FTIP panel. This turned on and off all
of the data recorders on the sled in the back. It's right above the three
fire-pull handles (LEFT/APU/RIGHT). To the left and right of the FTIP panel
are the ABEC (Analog Backup Engine Controller) panels and status lights, one
rubber on/off button with two 'FADEC FAIL' status lights to the left of the
button, and a single 'ABEC ENGAGE' button to the left. Full Authority
Digital Engine Controllers were new and unproven in the late 80's early 90's
for this application, and there was much gnashing of teeth over their
reliability. If both FADECS were to fail, (both lights illuminated) the crew
could select the ABEC to cut the FADEC out of the loop and go to a analog
command. As I recall it basically firewalled the engine. Never knew it to be
used other than test to see if it worked on the ground.

Now on to the 'Blottle', or, the TCL (Thrust control lever), clearly seen to
the right of the center console. It's twin is just off-screen to the left.
In the first couple of aircraft this controller moved much like the
collective in a H-47, but the sense was reversed, so that pulling the grip
up/back in a little arc was no power, down/forward was power. This caused
some confusion with helicopter pilots, worked just fine with the AV-8 guys.
A little elbow was rapidly milled for the junction of the Blottle and
cockpit floor, that put a 22(? i think) degree twist into the linkages, and
turned the movement into a nearly pure fore/aft movement, without the
up/down. This helped a great deal. The modern aircraft have a completely
different grip on the Blottle, (looks like the head from the monster in
Alien, and the movement is a pure fore/aft motion, along a slight tilt,
moves like a motor-boat controller). Nacelle control is the knurled knob in
the thumb-slot, various other comm buttons, hook jet., etc. The really
interesting thing on this control is the LTM wheel, set horizontally in the
face of the grip. Rolls left, right, with a detent in the center (white
line). This was the Lateral Translation Mode controller, a feature which I
do not think made the production aircraft. It used the fly-by-wire system to
command coordinated lateral cyclic inputs in both proprotor systems, and the
a/c would slide in pure translation right or left, without body roll, at a
rate proportional to the movement of the LTM wheel. It could also be used to
trim the a/c at a fixed roll angle, for slope landings. A really neat trick
to see the a/c hovering at a stable, set point of, say, 5 degrees bank
angle, with the pilots sticks centered and feet on the floor. I think it got
canned because it was not that useful, and added a lot of complexity to the
control system. But it was fun to play with.

Things to see in the Right Side Instrument Panel: Heck, still can't see if
the elbow joint on the PCL is an add-on or a production run. It's hidden
just behind the gray inertial reel for the harness protruding from the
seat-pan. The empty instrument rack bolted on to the right side of the
console looks like an afterthought, and it is. That's where the nose boom
instrumentation displays went, airspeed, attitude, altitude, etc. These were
used to calibrate and validate the digital system values.
The T-handle protruding from the lower right of the center console is the
parking brake, and I can't recall for certain what went into the well-worn
hole just below it. I am going to say that's where the pin that safed the
canopy jettison pryos was stored when it was removed, but I could have sworn
there were two. I may be mixing that up with the ejection seat pins, which
had different storage locations, on the first two aircraft. Yep, those went
on overhead holders, that's the canopy pin holder.

Overhead: Closest to us in the picture are the cabin light intensity
controllers, the Night/NVG switch is visible between the knobs. Forward of
that is the APU controller, with run/start/off/purge positions for the
rotary. It's in stop. Forward of that is the Digital Flight Control system
panel, with DFCS OFF select in the center, system A/B selects left and
right. Forward of that is the Analog Back-Up Nacelle Controller, with which
the pilot could override the Digital Controllers on the huge jackscrews that
rotate the nacelles in event of a malfunction or failure. The ABNCs would
move the nacelles at 2 degrees/sec as compared to the maximum rate of 7.5
deg/sec when digital. I don't think these were ever used other than to test
their functionality. Forward of that panel are the engine control levers.
Off/Crank/Start/Fly. Crank was to turn them for cooling, without fuel to
purge them after un-starts. Pretty much just put the engines in START until
they hit, oh heck, this is firing off way to many decayed brain cells, 88%
rpm, then push them to FLY. Really automated. The rotorbrake is the small
lever between the two levers. All the way forward are the hook controller
for sling loads, and contingency power system. The crew could select
contingency power and the DFCS would allow engine and transmission
operations in excess of 100% for short amounts of time. Below that is the
lonely wet compass, a relic of a different age.

Erk



  #7  
Old January 2nd 07, 03:44 PM posted to rec.aviation.military.naval
Don McIntyre
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Posts: 18
Default V-22 Osprey "ground effect" question: Cockpit stuff

Erk,
Thanks for the great info. Really puts some life into my photos.

Don McIntyre
Clarksville, TN

 




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