Aircraft Strut Sizes

[AndrewMcN]

I wonder if any body can help me? I am developing a new piece of equipment for charging a/c struts with HP Nitrogen and I want to calculate the volume of a strut. Now I already have the charging graph for a B737-300 / -500 which tells me the stroke vrs pressure but to calculate the volume I need the diameter of the silver piston on the main gear strut.

Does anybody know what this diameter is for the Boeing and any data at all on other aircraft struts even up to A380 sizes?

It would be very helpful if you can !

[rmm]

I'll look up the overhaul manual when I next get a chance. Maybe a few days though.

[AndrewMcN]

Thanks, it will be a great help.:ok:

[rmm]

I printed out the page today but left it at work. Doh! Will bring it home tomorrow. I do recall seeing a figure around 6.920".

[Alber Ratman]

I'm confused.

What new piece of equipment is required to charge an oleo strut of a classic, when a pressure regulator and thermometer is only required if the aircraft is jacked wheels clear of the deck and a regulator and a ruler if it's on the ground?

An adapter that stops shock strut mist coming out when you deflate the strut would be nice!:E

[rmm]

The diameter of the chrome strut on the 737 classic is 6.997" according to the good book. (main landing gear)

[glhcarl]

The diameter of the chrome strut on the 737 classic is 6.997" according to the good book. (main landing gear)

The "chrome strut" is actually the "chrome plated piston"!

[AndrewMcN]

The new equipment starts off with Liquid Nitrogen stores it at Tyre filling pressures and only compresses the gas required for the strut. Benefits include half price Nitrogen, no cylinders to handle, one normal trolley will hold the equivalent of 10 cylinders and lastly a nice gauge telling you how much gas you have before the shift starts, without having to open any valves.

The actual charging valves, hoses, regulators, thermometers and connectors etc are exactly the same as you already use.

Let me know what you think!!! :O

[AndrewMcN]

Thanks for this, I can now calculate the volume of the gas required for the strut and so design the vaporizers to supply the gas at the correct temperature.

[T.R Haychemu]

I'm a little sceptical to be honest. How often do you think MROs charge landing gears?
And how much will it cost? I'd imagine it'd need to work out a lot cheaper than 1/2 price nitrogen to offset any purchase costs.

Most places are happy enough with simple cylinders and contracts with the likes of BOC. Can your equipment be stored full of liquid nitrogen indefinately??

Sorry to put a downer on this, I just can't see why MROs would change from cylinders and the equipment/rigs they already have unless they were using a huge amount of N2 to make it worthwhile?

[Alber Ratman]

somebody already has done it. (http://www.semmco.com/ground-support-cryo-carts.php)

The RAF used them 20 years ago too. Bl**dy pain in the as*e to use. Bottles might be more expensive but are simples.. Connies can be trusted with them!:E

[AndrewMcN]

The Semmco ones are supplied by myself. I also supplied the RAF units. Its based on the user feedback on all the above equipments that a new generation can be built that provide the benefits without the problems. Remember the Sinclair ZX81, you would not compare that with a modern PC?

From the users point of view, the new machine will look like and operate like a cylinder trolley, in fact it will be a basic Semmco trolley with an add on cryogenic storage unit. The only difference is that when the operator wants HP gas he has to set a booster to run which gets up to pressure in about one minute.

LP gas is available for Tyres all the time. ;)

[AndrewMcN]

You can convert existing rigs, removing the cylinders and replacing them with the cryogenic tank.

The system fills all a/c systems including Tyres, Struts, Accumulators and Door assist cylinders.

Yes cost is an issue, but we already lease cryogenc equipment to Low Cost Carriers in the UK and Ireland at very low costs, we also supply the Liquid gas through BOC.

[Alber Ratman]

So is your furture design including a PLC (or whatever they are called now) that will set the charge pressure suppled to the ambient temperature for that particular type and component? Fine for when a kite is on sticks.

As ASFKAP as stated, charging struts is done infrequently on the line. Of course it is done more regulary in MROs as every C Check will include a strut service and sometimes aircraft must be dropped to get them in a hangar! Most MROs are conservative to say the least on what they will fork out for GSE. They don't see long term gain through short term pain, unless its cost cutting of jobs or conditions.

[good spark]

i think you would be better off spending your time inventing a machine to get the six numbers on saterday night
this is re-inventing the wheel



gs

[AndrewMcN]

I have already done that, the numbers are 4,14,18,24,41,44 bonus 25 !!!

I am just doing this for fun, inventing a better cheaper wheel.
:ok:

[mono]

I too am sceptical. How are you going to get Cryo stored gasses up to ambient temps? LP or HP.

Remember an MRO is going to want to use this kit for all its charging needs. It's impossible to know the volume of gas required to top up accumulators for example (unless they are fully depleted and even then you'll need a chart for every a/c type). With an N2 rig I can top up an oleo in a matter of minutes and I'm not sure N2 cylinders are that expensive.

You'll need a chart for every a/c type and position (nose or main) if the volume needs to be known. Pumping up tyres would be a problem if the gas is just above liquid temps as there would be a considerable pressure increase as the temperature rose to ambient. Not that I want to rain on your parade, it's just that I don't think it's that simple.