Bent Albert

[Kim Il Jong]

Heard a rumour that, in preparation for today's farce at Lyneham, one of Her Majesty's finest Fat Alberts was put in the undershoot at Lyneham buy a fair margin, somewhat reducing the serviceability of the airfield lighting not to mention the ac.

Anyone care to correct me/ shed further light on this one??:O

[Logistics Loader]

Heard rumour it was a very heavy landing ... 4g was quoted...
How true, no idea but doesn't help when a/c are in short supply....

[Always_broken_in_wilts]

Just what the J fleet needs...............another broken K:}

Thank **** the the two J squadrons are not working hard:}

all spelling mistakes are "df" alcohol induced

[Jackonicko]

Long or short? (eg 1, 3 or 3A?)

[monkeybumhead]

Jacko

Work it out old boy, it isn't hard really is it?

Oh by the way, it appears that someone tried to blame the groundcrew for getting the 700 out late. If that makes you rush a landing then what hope have we got.

[Jackonicko]

Sorry Monkeybumhead, you haven't been here long, so there's no reason for you to know that I'm really not very bright, and do need some spoon feeding. I know what UNDERSHOOT means, but as to which variant....

[US Herk]

Heard rumour it was a very heavy landing ... 4g was quoted...

The g-meter in Albert is not for use during landing & any readings obtained from "heavy landings" do not relate to reality.

In flight, it measures where it sits, not the centre of the wings (which "feels" approx .2g more than indicated up front), so is inaccurate.

During landing, it is nothing more than "bounced" deflection of the needle & movement within that is "recorded" on the gauge itself...

Albert is rated for max descent rate of 9ft/sec which equates to 540ft/min - if you impact that hard, you'll likely turn on every emergency exit light in the acft!!

I'm not implying that rumoured landing discussed above was not hard/heavy/out of limits, merely that you cannot discern such from the g-meter in the cockpit.
;)

[Logistics Loader]

Thanks for clarifying the point...

I have a genuine ques though on descent rates.....

Is the Khe Sahn descent profile >540ft/min ???

[flipflopman RB199]

Forgive me if I am speaking out of turn, as I am unfamiliar with Hercs, but how does the fact that the cockpit accelerometer reads 0.2g less than the Airframe accelerometer mean that it is inaccurate??

Surely if this is the case there would not be one fitted?

On the Tornado, there are 3 banks of readings, each from a different area of the fuselage which each give a different reading. Which one is the accurate one?????

Tornados, Harriers, Jaguars all have seperate Cockpit and Airframe 'g' meters, and the readings from both are recorded by the groundcrew, and entered into the F700 for fatigue monitoring purposes, and there is rarely a discernible difference between the two.

As for your explanation that this is merely the needles "Jumping about", what a load of horsecr4p. If this were the case, according to Newtons laws of gravity, upon sustaining a heavy landing, the needles would be deflected downward under their own weight, thus showing a NEGATIVE reading, as opposed to a 4g positive reading.

Had a heavy landing and tried bullsh1t your way out of it before US Herk?

[spaniels ears]

just to clarify for logistics loader, the 540ft/min rate of descent relates to the actual point of touchdown. the descent prior to this can be much steeper (as in the khe sanh technique), but you must arrest the rate of descent at the last minute or bad things will happen. our rb 199 friend certainly seems to know a lot about albert. the flight deck g meter is an indicator only, giving the captain an instantaneous heads up of a potential overstress. all fatigue readings on the herc are taken from the airframe fatigue meter. the reason that this is different from a tornado is that, believe it or not, they are different aeroplanes.

[RedFlag]

Is the Khe Sahn descent profile >540ft/min ???

540ft/min refers to the ROD at touchdown, not during the approach, and the touchdown ROD is also related to AUM and fuel distribution. ROD on approach is unrestricted in terms of airframe stress.

damn, beaten by a minute....

Must learn to type quicker!

[On_The_Top_Bunk]

Spaniels ears

giving the captain an instantaneous heads up of a potential overstress

ROFL..... if the captain can see it behind his knee whilst attempting a tricky manoevere and scanning the primary instruments mhmmmmmmm


For those that don't know its not placed in the best position for monitoring.

[country calls]

To further clarify for you rb199man the reason there are three banks on the flying flick knife are the sweepy wings. And that is why on the GR version the most readings are on the middle bank equating to 45 degrees of sweep, where most of the flying is done.

The guage as opposed to the meter on Albert is up front and having been fitted in the mid 60s and never serviced since is quite possibly wildly inaccurate. The meter shuts off at less than 150 knots so thats no good either


As far as I remeber having spent 18 years on Tornado there has never been anywhere to record the cockpit reading.

As for your Newton theory its the weight inside the instrument which drives the needles against a spring. Weight heaver than needles, so thats how it records positive.

I think apologies should be winging there way across the pond round about........now

[flipflopman RB199]

Thank you Spaniels Ears.

As your RB199 friend states, he clearly does not know much about Albert, as he states.

Forgive me if I am speaking out of turn, as I am unfamiliar with Hercs,

However, as an experienced engineer, I have a very good understanding of how the accelerometer system works. Yes, the cockpit gauge is an indicator to the aircrew of the airframe 'g' loading, as it is on ALL aircraft, but are you suggesting that the 'g' loading differential between the cockpit and main accelerometer is going to be sufficiently different as to say the landing was within limits? No, of course not. If US Herk's stats are correct, there is a 0.2'g' differential between the cockpit gauge and airframe accelerometer.

Is 3.8'g' enormously different to 4'g'?

If it is, please excuse my ignorance and put it down to the fact that I am obviously getting confused with the fact that a Hercules is a completely different aircraft to the Tornado.

Country Calls,

Are you absolutely convinced that the accelerometer fitted to Albert has been fitted since the 60's and never serviced? Only that strikes me as being a somewhat unquantified statement. I personally have been seen numerous 'g' meter/accelerometer changes due to unserviceability over my years in the RAF, which would mean I have clearly wasted a lot of time over the years on jobs that obviously did not need doing?:confused:
I refer to the cockpit gauge being recorded, as that is the first indication groundcrew have of any overstress, and the starting point of a more detailed investigation. After 18 years on Tornado, I defy you to take the fatigues, and know at a glance that there is amything amiss.
Thank you for your explanation of the 3 banks:rolleyes: I was merely trying to show how there are minute differences all across the airframe, but these are nowhere near in the range of 2-3'g'. Nor would the cockpit gauge ever jump about in the region of 2-3'g' during a heavy landing, or this would happen every time the A/C pulled any 'g' whatsoever.


and breathe out.............


Edited to answer Country calls

[phutbang]

You will find the before state here!!! (http://www.ukar.co.uk/board/ikonboard.cgi?;act=ST;f=9;t=7836)

However well done for the engineers for turning out a spare on top of their already excessive work load. :ok:

[Blacksheep]

The simple cockpit mounted 'G' meters in most British military aircraft are designed to indicate relatively steady state forces. In the event of an impact, cockpit readings will not be an accurate reflection of aircraft structural loads. Strain gauges and/or Fatigue Meters installed near the aircraft CoG are designed to record these forces (strain gauges measure actual deflection of the structure).

'Fast Jet' combat aircraft are usually better instrumented for vertical 'G' forces to ensure crew awareness of wing loading (lower stall speed at high G) and the 'G' force they themselves are experiencing. They still have fatigue meters though.

[monkeybumhead]

I haven't yet seen the damage but I doubt it will be as good as the Kenya ar$e slap that required a kimwipe and speed tape repair to get home.

[BEagle]

'Fast Jet' combat aircraft are usually better instrumented for vertical 'G' forces to ensure crew awareness of wing loading (lower stall speed at high G) and the 'G' force they themselves are experiencing.

Huh?

The cockpit 'g' meter is there to assist the pilot in staying within the 'g' limits. They are normally very simple devices and very reliable. The meters, that is...

But 'lower stall speed at high G'? Not so! The stalling speed of any aeroplane increases with the square root of the load factor. So, if it stalls at 100 kts in 1g flight, it will stall at 141 kts in 2g flight, 200 kts at 4g......, 268kts at 7.2g etc.

FJ pilots should be aware of the IAS which allows them to pull to the pre-stall buffet nibble without overstress - but they certainly won't be looking in at a cockpit accelerometer when doing this!

[Logistics Loader]

Thanks guys for the reply on descent rates, as a glider pilot, i have done steep descents, but am always impressed by the Khe Sahn approach...

Might have to try the simulator to see what its like

[SirPeterHardingsLovechild]

While you lot are showing off discussing g-meters, fatigue meters, and the square root of the load factor...

Take it from me.

Its much better to use the wheels when landing aircraft.

[Logistics Loader]

assuming of course , someone remembers to lower them...!!!

[DEL Mode]

Just to point out two things.

1. How do you test a cockpit "g" indicator? - Answer you drop it in a vertical axis. Does the RAF have such a test which guarantees the appropriate accuracy? I would ask the question before assuming it is an accurate indication of the actual “g” recorded during a sortie. That is why it is an indicator, and not a gauge.

2. Secondly the 15 or so feet between the gauge and the accelerometer in a Tornado will lead to an error in the readings between the cockpit gauge and the ADR/Fatigue meter. Ever so small, but significant enough.

[rolandpull]

So Chaps,

forgive me for being a techno-phobe, but getting back to the thread:
1. did it undershoot?
2. did it get bent?
3. any piccies?

Anyway G meters are for analysts. Incidentally the first for letters of which happen to be anal!

[Always_broken_in_wilts]

2. Secondly the 15 or so feet between the gauge and the accelerometer in a Tornado will lead to an error in the readings between the cockpit gauge and the ADR/Fatigue meter. Ever so small, but significant enough.

Now if I was a clever chap who built this sort of thing I reckon I could come up with some sort of compensation method to take care of the error mentioned.....just seems like the logical thing to do to me:rolleyes:

all spelling mistakes are "df" alcohol induced

[KPax]

To get back to the original post, the ac struck the grass before hitting the threshold and ripping out a couple of threshold lights. Bits of the ac were still being picked up from the threshold the following morning.

[US Herk]

Forgive me if I am speaking out of turn, as I am unfamiliar with Hercs,
Yes, obviously.;)

how does the fact that the cockpit accelerometer reads 0.2g less than the Airframe accelerometer mean that it is inaccurate??
g limits are typically measured from the intersection of pitch/roll/yaw axes - which usually is near the centre of the wing. I suppose I could concede it is accurate for its placement, but is inaccurate WRT acft limits.

As for your explanation that this is merely the needles "Jumping about", what a load of horsecr4p. If this were the case, according to Newtons laws of gravity, upon sustaining a heavy landing, the needles would be deflected downward under their own weight, thus showing a NEGATIVE reading, as opposed to a 4g positive reading.

Well, you've already been told you're wrong on the pos/neg. What the needles are recording is the spring-weighted movement inside reacting to something it is not intended to measure - impact forces.

Allow me to quote from Mr. Lockheed:

"A Type MA-1 accelerometer, located on teh pilot's instrument panel, gives instantaneous as well as maximum and minimum readings of the g forces exerted on the airplane. The gage scale indicates readings from plus four g's to minus two g's. The maximum and minimum indication needles will remain at highest readings until the push to set button on the gage case is pushed, then they will both retun to plus one g and will again register maximum or minimum readings of g forces until again reset. The accelerometer is designed for inflight use only and does not accurately measure g forces during landing. This instrument is to be used in conjunction with the information on structural limitations in section V."

Had a heavy landing and tried bullsh1t your way out of it before US Herk?
On the contrary - the one time I had a landing that I considered marginally heavy, I immediately turned it in to engineering for inspection. I only considered it marginal based on the fact that two of the emergency exit lights in the rear of the aircraft came on. I would never bullsh1t my way out of anything that could compromise the aircraft integrity & do not appreciate your insinuation that I would.

FWIW - The emergency exit lights in Albert have inertia switches in them that turn them on if subjected to a decelerating force exceeding 2.33 gs. While that isn't a limit anywhere, they don't come on during even firm landings, so I considered it an indicator of something excessive & the prudent thing was to turn it in. Engineering wasn't happy about it, nor was I proud of it, but it was absolutely the correct thing to do.

ROFL..... if the captain can see it behind his knee whilst attempting a tricky manoevere and scanning the primary instruments mhmmmmmmm
Quite good fun during FE whilst OLFing!;) :D

The simple cockpit mounted 'G' meters in most British military aircraft are designed to indicate relatively steady state forces. In the event of an impact, cockpit readings will not be an accurate reflection of aircraft structural loads. Strain gauges and/or Fatigue Meters installed near the aircraft CoG are designed to record these forces (strain gauges measure actual deflection of the structure).
YES! Thank you, Blacksheep!

1. How do you test a cockpit "g" indicator? - Answer you drop it in a vertical axis. Does the RAF have such a test which guarantees the appropriate accuracy? I would ask the question before assuming it is an accurate indication of the actual “g” recorded during a sortie. That is why it is an indicator, and not a gauge.
Since my father owns/operates an FAA approved avionics & instrument shop, I can tell you that dropping something, while a good way to measure durability, is a cr4p way to measure a meter's accuracy. Typical cockpit g meters are assembled with springs. Springs can be tested. They also have movements. Movements can be tested. If both are within limits, dropping the g meter can only induce damage & inaccuracy!

I had hoped I would have my Lockheed Tech Manual here at home so I could post a pic, but I don't and have only my aircarft operating manual (quoted above). As I'll be slipping the surlies tomorrow, I'll have a look & see if there's a good piccie of the inner workings of the g meter - as they say, a picture is worth 1000 words and after you see the guts of it, you'll understand why they're not accurate during landing!:ok:

I think apologies should be winging there way across the pond round about
Naw, I'm actually on island!;) Besides, I've got thicker skin than that!:ok: :E:

[Blacksheep]

How do you test a cockpit "g" indicator?The Standard Serviceability Test (SST) for bench testing a cockpit 'G' meter or more properly an accelerometer, is to rotate it slowly while monitoring the pointer movement for sticking. When on its side the indication is Zero 'G' and when upside down the reading is Minus One 'G'. There is no bench test for the higher figures, though one supposes that factory testing includes the use of a machine that can induce calibrated acceleration forces.

[Hammer Head Too]

Gotta agree with US Herk on this one. Landed many gliders with panel mounted G meters, go over a runway lip, uneven ground, a medium size stone, even a rabbit hole and watch the G meter jump !! 2 or 3 easy:\