Can Harriers ground-taxi backwards?

Hopefully Frijoles or some other current or former Harrier
type can answer this (whatever happened to Cecil Turner?).
Using braking stop it would seem at least theoretically
possible, but I don't know if there were other problems that
prevented it (hot gas re-ingestion/FOD, light on the wheels,
etc). Assuming it is doable and NATOPS allows it, is/was it
done rarely/infrequently/routinely on an LPH/LHA/LHD? I was
just wondering if it were possible to taxi cross-deck and
get lined-up, then backup to maximise T/O run, thus allowing
more a/c to be launched in a short period of time than if it
were necessary to use deck tractors for positioning. Or is
the deck wide enough and the maximum angle of the Harrier's
nosewheel steering gear great enough that it can taxi aft
and then essentially make a U-turn at the aft end of the
deck, wasting little or no T/O run? TIA,

Guy

Guy Alcala wrote:

Hopefully Frijoles or some other current or former Harrier
type can answer this (whatever happened to Cecil Turner?).
Using braking stop it would seem at least theoretically
possible, but I don't know if there were other problems that
prevented it (hot gas re-ingestion/FOD, light on the wheels,
etc).

Not only theoretically but practically possible.

Assuming it is doable and NATOPS allows it, is/was it
done rarely/infrequently/routinely on an LPH/LHA/LHD?

And permitted by NATOPS. After 513's first deployments on LPHs,
the AV-8A was never routinely deployed aboard LPHs as they are
aboard the LHA/LHDs [typically, a 6-aircraft det as part of the
composite helo squadron of the MEU]. "Backing up" was routine,
IME, but generally aircraft movement/spotting was planned such
that it wasn't needed.

I was
just wondering if it were possible to taxi cross-deck and
get lined-up, then backup to maximise T/O run, thus allowing
more a/c to be launched in a short period of time than if it
were necessary to use deck tractors for positioning. Or is
the deck wide enough and the maximum angle of the Harrier's
nosewheel steering gear great enough that it can taxi aft
and then essentially make a U-turn at the aft end of the
deck, wasting little or no T/O run? TIA,

The latter, we called it the "conga line" was the standard
practice. LHA/LHDs are wide enough to do that. Deck runs for
the AV-8A, even for the most restricted engines, was always short
enough to permit a 6-aircraft line-up to come down the starboard
side, make the Uie at the aft end of the flight deck and then
line up starting behind the 450' deck-run marker. Typically, a
55/55 STO would take 250-350', if twenty-mumble year old memory
serves.
--
OJ III
[Email to Yahoo address may be burned before reading.
Lower and crunch the sig and you'll net me at comcast.]

Ogden Johnson III wrote:

Guy Alcala wrote:

Hopefully Frijoles or some other current or former Harrier
type can answer this (whatever happened to Cecil Turner?).
Using braking stop it would seem at least theoretically
possible, but I don't know if there were other problems that
prevented it (hot gas re-ingestion/FOD, light on the wheels,
etc).

Not only theoretically but practically possible.

Assuming it is doable and NATOPS allows it, is/was it
done rarely/infrequently/routinely on an LPH/LHA/LHD?

And permitted by NATOPS. After 513's first deployments on LPHs,
the AV-8A was never routinely deployed aboard LPHs as they are
aboard the LHA/LHDs [typically, a 6-aircraft det as part of the
composite helo squadron of the MEU]. "Backing up" was routine,
IME, but generally aircraft movement/spotting was planned such
that it wasn't needed.

I was
just wondering if it were possible to taxi cross-deck and
get lined-up, then backup to maximise T/O run, thus allowing
more a/c to be launched in a short period of time than if it
were necessary to use deck tractors for positioning. Or is
the deck wide enough and the maximum angle of the Harrier's
nosewheel steering gear great enough that it can taxi aft
and then essentially make a U-turn at the aft end of the
deck, wasting little or no T/O run? TIA,

The latter, we called it the "conga line" was the standard
practice. LHA/LHDs are wide enough to do that. Deck runs for
the AV-8A, even for the most restricted engines, was always short
enough to permit a 6-aircraft line-up to come down the starboard
side, make the Uie at the aft end of the flight deck and then
line up starting behind the 450' deck-run marker. Typically, a
55/55 STO would take 250-350', if twenty-mumble year old memory
serves.

Ogden, thanks very much for the reply. The reason I asked is I was
wondering about this in the context of the maximum number of Harriers
that could be reasonable launched for a single strike on smaller
carriers like an Iwo Jima, Spain's Principe de' Asturias, Italy's
Guiseppe Garibaldi or the RN's Invincibles, with shorter and narrower
flight decks than an LHA/LHD. To take an example, Pd'A has a maximum
take-off lane length of 575 feet, allowing a maximum of about 550ft.
t/o run (from the nosewheel) if the main gear is backed up to the
after edge of the flight deck (ie the aft fuselage is overhanging).
Photos seem to indicate that they normally spot 2 a/c nose to tail
for t/o if conditions allow (either fairly light loads or else high
winds/moderate temps), but usually seem to park about 3 Harriers in
an arc around the starboard aft end of the flight deck, with one more
spotted for t/o, probably allowing a 450+ ft. t/o run for a/c 2, 3
and 4, if they taxi into position and don't back up once lined up.

Although their flight decks don't seem to be significantly wider than
the others, the Invincibles islands appear to be narrower, with
enough room to park Harriers (at least, the shorter-wing Harrier I
variants) at an angle, abreast the island and clear of the foul line,
so theoretically they could taxi aft when it was their turn and turn
around. Pd'A and Garibaldi don't seem to have that much width
abreast the island, although their islands are shorter so they could
taxi a/c parked forward of it aft, once it was clear to do so,and
with some time delay.

Tests carried out by the USN on Pd'A with AV-8Bs (-406 engine) to
establish flight limits and t/o requirements showed that in tropical
day conditions (presumably 103 deg. F at SL) with 30kt. WoD, at a
weight of 28,700 lb. for a CAP mission with two tanks, gun and ammo
and 4 AIM-9s, an AV-8B would need to use the entire 550 ft. deck
run. The radar-equipped AV-8B+ now used by the USMC, Spain and Italy
has about 2,000 lb. more thrust from the -408 engine than was
available from the AV-8B's -406, but the empty weight is about 1,000
lb. more too, and I don't know if there's a net gain or loss in STO
performance for the same load.

Under the same conditions from a flat-deck (no ski-jump) ship like
any of the US phibs, -406 engined AV-8Bs were unable to take off with
anywhere near that load, being restricted to a maximum of approx.
(eyeballing the graph) 26,500lb. if taking the maximum LHA/LHD deck
run of 800ft. Even with a more typical strike load of 6 x Mk.82
snakeyes, gun and ammo and ECM pod, it still grosses 26,982 lb.,
which is still over the maximum possible t/o weight using the entire
deck (again, Tropical Day conditions).

Since we and other countries have been flying most all of our combat
and potential combat missions in tropical conditions (those numbers
seem fairly representative of the Persian Gulf/IO), I'd think the
need to make max. t/o runs would be pretty routine for such loads.
Assuming that's the case, the ability of the a/c itself to taxi until
lined up and then back up to allow it to use the max. t/o run, should
decrease the t/o interval between a/c and thus allow more a/c to
launch as part of the same formation.

I know the USMC pilots on the Guam for the tests back in '73 and '74
weren't too keen on cross-deck taxying when the anti-skid coating was
worn, as the Iwo Jimas had a rep for rolling. They would have
preferred a turntable at the after end of the flight deck, similar to
the ones on the vehicle/tank decks of LSTs etc, that would allow them
to taxi all the way aft and then be rotated 180deg. into t/o
position. But in addition to the extra cost that involved lots of
weight at flight deck level and dependence on complicated machinery
exposed to the weather, so it didn't feature in the final SCS design
(of which Pd'A is an slightly stretched version).

Guy

In article ,
wrote:

I know the USMC pilots on the Guam for the tests back in '73 and '74
weren't too keen on cross-deck taxying when the anti-skid coating was
worn, as the Iwo Jimas had a rep for rolling. They would have
preferred a turntable at the after end of the flight deck, similar to
the ones on the vehicle/tank decks of LSTs etc, that would allow them
to taxi all the way aft and then be rotated 180deg. into t/o
position. But in addition to the extra cost that involved lots of
weight at flight deck level and dependence on complicated machinery
exposed to the weather, so it didn't feature in the final SCS design
(of which Pd'A is an slightly stretched version).

Guy,
other (good) comments notwithstanding, "complicated machinery
exposed to the weather" doesn't cut it. This type of machinery had been
used for decades on the surface fleet, exposed to the weather, with
little if any problems. Think gun turrets.
The weight issue is probably the deciding factor. Probably made the
ship too stern heavy.

--
Harry Andreas
Engineering raconteur

Harry Andreas wrote:

In article ,
wrote:

I know the USMC pilots on the Guam for the tests back in '73 and '74
weren't too keen on cross-deck taxying when the anti-skid coating was
worn, as the Iwo Jimas had a rep for rolling. They would have
preferred a turntable at the after end of the flight deck, similar to
the ones on the vehicle/tank decks of LSTs etc, that would allow them
to taxi all the way aft and then be rotated 180deg. into t/o
position. But in addition to the extra cost that involved lots of
weight at flight deck level and dependence on complicated machinery
exposed to the weather, so it didn't feature in the final SCS design
(of which Pd'A is an slightly stretched version).

Guy,
other (good) comments notwithstanding, "complicated machinery
exposed to the weather" doesn't cut it. This type of machinery had been
used for decades on the surface fleet, exposed to the weather, with
little if any problems. Think gun turrets.

Harry, gun turrets are enclosed, with the turret rotation mechanism
protected to a greater extent than would be the case with a flight-deck
turntable (and yet they still jam or malfunction). In addition, ships tend
to have multiple gun turrets, so failure of one doesn't mean total loss of
capability. For much the same reason of redundancy, a/c carriers usually
have at least two elevators. Of course, as long as a/c could still make a
U-turn on their own, malfunction of the turntable wouldn't cause a total
loss of capability, just a slowdown.

The weight issue is probably the deciding factor. Probably made the
ship too stern heavy.

I think trim was unlikely to be the issue; stability (adding weight up high)
was most likely to be the main factor, possibly requiring an increase in
beam.

Guy