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-   -   Harrier transition to and from hover (https://www.pprune.org/military-aviation/414038-harrier-transition-hover.html)

John Farley 7th Mar 2014 14:47

LowObservable

Dunno why the type of landing should affect the tyres - unless of course you are trying to keep below a wheel/tyre RPM limit at very high conventional touchdown speeds.

sandiego89 7th Mar 2014 15:31

I believe the F-35B has been experiencing high wear rates on the tyres/tires. The B has a different tire maker than the A and C models. Perhaps a design or manufacturing issue. I wonder if heat from V/STOL operations and the rough non-skid on deck contributes to the high wear rates.

Good article here: http://defensetech.org/2013/09/19/5t...eration-tires/

Engines 7th Mar 2014 15:40

JF, Guys,

During the F-35 weight reduction effort all three variants were looking for pounds to lose and the landing gear came under scrutiny. (yes, should have been done during design first time around but LM didn't have a Chief Designer at that time and they took their eyes off the weight ball).

Anyhow, it was found that some conservative assumptions had been made for landing speeds, weights, temperatures, surfaces, runway lengths, repeated landings etc., which had led to fairly chunky wheel and brake units. On further examination, the LM team found some new tyres (I think they were French) that offered good performance with significant weight reductions. I think that they ended up with three tyre types for A B and C, choices driven by conventional landing weights/usage spectra. Brake units were also tailored across the three variants (remember that the F-35A and C had serious weight issues as well).

So, the main balance for F-35B was to provide the best possible conventional landing braking performance (and tyre life) while keeping weight down as much as possible, driven by the need to achieve the mandated Vertical Lift Bring Back (VLBB) figure.

Hope this helps a little

Engines

John Farley 7th Mar 2014 17:14

Engines

Many thanks.

JF

orca 7th Mar 2014 18:30

Noprobs,

I think the crude device was termed the Pressure Drop Regulator...pushes spectacles up nose with right trigger finger...it was certainly PDR on all the diagrams.

Helmut Mann 8th Mar 2014 19:50

Some great info here, thanks guys.


I was looking at a pic of the Harrier (II, I think) with the gear extended and I note the nose gear doors are closed at the tyre end of the system but the leg end is obviously open around the pivot end of the leg with a very tight opening allowed around the leg. Why is this? Does the door-closed system prevent damage to internal systems (eg Hydraulics) during the vertical take off or landing, from FOD produced by the downward thrust or is there something more to it?

achillesat23 13th Mar 2014 12:22

Clarification on frs sea harrier behaviour
 
Dear john farley sir....

I am one of harrier frs mk 51 operators from india.... recently in one of the aircraft during AMTFi noticed a peculiar problem.... the details are as follows...

1. During trim checks... at 450 knots, with mid flaps.. the rudder and aileron trim is out by half gauge width... with nozzles aft and undearriage up... however... during 190 knots with flaps mid, nozzles aft, uc down the trim required is neutral...

we carried out rigging and took her up again.... now the defect reversed... ie at 450 neutral trim and at 190 knots trim reqd is high...

2. Another observation that, at any speed during straight and level flight, just by increasing engine speed and with no increase in speed the aircraft is rolling to left....and on decrease in engine rpm the aircraft is rolling to right....

we are trying to find a solution but unable to find any reasons.... could pls suggest some ideas as to why it should happen....we ecently changed the engine.... previously there was no defect.... regards

John Farley 13th Mar 2014 18:49

achillesat23

Poor you! Over the years there have been many cases of odd trim changes.

When you think about it there are so many things that can affect the trim of a Harrier aircraft that it is amazing that there are two aircraft the same!

However you say you carried out rigging checks but not if you changed anything or things. So I would suggest the following:

Make sure the aerodymamic control surfaces are rigged within limits including the flaps when in the mid position.

Carry out the 450 knot check carefully and adjust the gauges as necessary to indicate zero on both.

From now on only adjust/change one thing per flight

If you are still unhappy with the 190kt gear down, flaps mid and nozzles aft situation look at your engine options.

Individual nozzle angles when aft selected. (having a rear one down even a little can change a lot of flow at the back end)

If these angles need changing re fly and do the 450 check and adjust again.

If still unhappy:

Swop the front nozzles (L/R)

Reset the 450 kts as required.

Finally - and this is the most likely cause of the confusion - swop the rear nozzles. These of course contain the engine trimmers which have been known to significantly affect overall aircraft trim with changing RPM at constant IAS. We have also found moving a trimmer's position in its own nozzle can also help.

Reset the 450 kts as required because in the end of course what really matters is the 450 kt trim setting as this affects gun aiming accuracy.

Good luck!

JF

Dan Gerous 14th Mar 2014 12:07

Helmut, have you recently acquired a Harrier, without an owners manual?



achillesat23 19th Aug 2015 16:05

Final Phase of FRS MK51 IN issues..
 
Dear John sir..

In first place I would like to convey my apology for not getting back on the harried unintended roll issues as I had got transferred out shortly there after...

A brief on the previous problem.. We had carried out all kinds of combinations as you suggested and with no result we were about to name "the rogue" as the rogue again... However the problem was solved by replacement of fin.. Which to our surprise the least suspected part... The aircraft is still up in the air and she is as beautiful... Just did a 90deg turn during hover and landed her...

Thank you sir...

Courtney Mil 19th Aug 2015 16:23

Thank goodness. I've been worrying about that for a year and a half now.

achillesat23 19th Aug 2015 16:25

Harrier hover performance and its implications..
 
Dear john sir...

We are presently at the final phase of Harrier operations and are faced with new problems.. Till date the Harrier never ceases to amaze me with respect to its capability and technical brilliance this aircraft posses...

Coming to the issue at hand...

Presently the engines that are being rolled out of the overhaul facility are sitting close to high margins due to use of various components including turbine... Notwithstanding they are within test bed acceptable limits...

However, when installed on aircraft... The hover performance values are sitting extremely high at Wh -7(minus 7) and Jpt of +40.... Which is completely out of the graph itself... We are faced with the dilemma...

The fact that I am again back as Sqn Harrier Eng Officer forces me to look to various factors and forces me to think out of the box ideas to sustain the jets for some more time...

My concerns and questions are as follows:

1. What does the hover performance indicate with regard to overall health of the engine... (The case in point is.. Though the perf hover values are high.. The ELR counts are less.. It eats abt 3 to 5 per normal sortie.. That's in Indian conditions )

2. Can the aircraft/ engine still be exploited with such hover values primarily for non VSTOL flight regimes keeping VLanding to completley minimal (beggers can't be choosers.. So is the question )

3. We had 3 engine surges during PRL checks in last one year... Is it anyway connected to poor hover performance leading to poor perfoance of the engine through out normal flight envelop...

These things have not been answered in publications and manuals.. It becomes imperative to draw conclusions... The primary aim being not to reject an engine without proper reason... The case in point being... VSTOl opeartions are not that imp as we are trying to sustain this beauty just for few more months...

Your valuable inputs will be greatly appreciated sir... Hope I haven't made a fool of myself asking this... On the lighter side sir...

Regards... Probably Last Engineer of Legacy Jumpjets... Achilles...

achillesat23 19th Aug 2015 16:29

Harrier roll
 
Ha-ha.. Thanx a lot for concern and extremely sorry for late reply.... Loved to see you remembering abt the problem....

peterperfect 24th Oct 2016 19:41

1 Attachment(s)
Going through an old photo album recently I found this unusual shot of a Sea Harrier on RFA Olwen, I'm guessing its John F ? Love to hear any good tales of trials flying off a flight deck that small !

cornish-stormrider 25th Oct 2016 11:56

Nice to see that the bona jet is still out there and you are still having the old fun n games trying to keep it in the air

TEEEJ 25th Oct 2016 12:25


Originally Posted by cornish-stormrider (Post 9552584)
Nice to see that the bona jet is still out there and you are still having the old fun n games trying to keep it in the air

The Indian Navy retired the Sea Harrier during May 2016. Replaced by the MiG-29K.


The illustrious and unique Sea Harriers of Indian Naval Air Squadron (INAS 300) were given a befitting farewell in a function organised at INS Hansa, Goa on Wednesday.

The function was attended by Admiral RK Dhowan, Chief of the Naval Staff, Vice Admiral Sunil Lanba, Flag Officer Commanding in Chief Western Naval Command, serving and retired Officers and men of the Indian Navy and all personnel who have served in the INAS 300.

.....

In appreciation of the faithful service to the nation by INAS 300 'White Tigers', an impressive ceremony was held today which saw the Sea Harriers fly for one last time, and MiG-29K flanking their outgoing cousins and ceremoniously taking their place.

The air display included supersonic pass by MiG 29s and formation flying by two each Sea Harriers and MiG 29Ks.

The composite air display symbolized a smooth transition from the old to the new in continuance with the proud legacy of the INAS 300.

On completion of the Air display, 'washing down of the Sea Harriers' was carried out in a traditional manner. A first day cover was also released by Admiral RK Dhowan to mark the occasion.
Indian Navy bids farewell to iconic Sea Harrier, welcomes MIG-29K fighter jets | Latest News & Updates at Daily News & Analysis

John Farley 25th Oct 2016 16:11

peterperfect
 
Not me sir. Size is not a problem as given the approriate visual cues you can easily position a Harrier VL to a couple of feet.

However - and it is a big however - ship motion is what it is all about. That can change everything.

Bro 26th Oct 2016 12:01

Deck landing facing aft with the wind from astern was good for a laugh.

ExRAFRadar 26th Oct 2016 21:47

What a great thread

Wander00 27th Oct 2016 10:37

JF - bought a copy of your book at the LAA Rally - a brilliant read, and brain cell provoking. Now reading it for the second time. Many thanks, I hope other readers enjoy it as much as I am


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