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British APC/IFVs, why doors and no ramp?


Loopycrank
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On 4/18/2021 at 6:46 AM, Ssnake said:

You can just as well hoist it with a steel cable.

That being aid, hydraulic systems as such don't take up much space (that's why engineers love them if volume constraints are significant), and if you have a hydraulic system already, laying two pipes to operate the door isn't going to be a significant complication. The main argument against hydraulics is that they are horribly inefficient; about 40% of the energy input dissipate into internal leakage.

The main problem with hydraulics in AFVs is the hydraulic fluid burning in the event of the vehicle being hit.  I recall this being a particular issue with the turret traverse in M60 spraying the oil from punctured pipes in a mist which then ignited causing a flash fire in the turret when Israeli tanks suffered hits.

In some cases, particularly maintenance and engineer variants, hydraulic systems internally are inevitable.  The ram for the rear door on the Warrior section variant is well hidden at low level and Challenger ARRV has a separate winch compartment, but I have been in REME Warrior variants where winch and crane hydraulic pumps were a bit more exposed!

Best,

Greg.

Edited by GJK
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...or you build a powerful electrical subsystem and then use servo motors etc.

Not quite so low volume as hydraulics, but less of a fire hazard obviously.

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36 minutes ago, GJK said:

The main problem with hydraulics in AFVs is the hydraulic fluid burning in the event of the vehicle being hit.  I recall this being a particular issue with the turret traverse in M60 spraying the oil from punctured pipes in a mist which then ignited causing a flash fire in the turret when Israeli tanks suffered hits.

In some cases, particularly maintenance and engineer variants, hydraulic systems internally are inevitable.  The ram for the rear door on the Warrior section variant is well hidden at low level and Challenger ARRV has a separate winch compartment, but I have been in REME Warrior variants where winch and crane hydraulic pumps were a bit more exposed!

Best,

Greg.

  I think the bigger problem is you are looking directly at the clear fuel tank that's mounted on the side wall when sitting in the back seats of the REME warrior variants repair and recovery. This is especially the case when the crew tell you not to look at them just before they drive you cross country as it is very well known for inducing extreme nausea.

Edited by Wobbly Head
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1 hour ago, Wobbly Head said:

  I think the bigger problem is you are looking directly at the clear fuel tank that's mounted on the side wall when sitting in the back seats of the REME warrior variants repair and recovery. This is especially the case when the crew tell you not to look at them just before they drive you cross country as it is very well known for inducing extreme nausea.

Diesel doesn't have the same combustion properties as hydraulic oil.  Give me motion sickness over flash burns any time!

In all Warrior variants the fuel tank is in the centre under the turret or cupola, so no-one has to stare at it.  The clear plastic tank was changed to a translucent one around the early/mid 90s (I think) to reduce the motion sickness induced by watching the fuel slosh whilst bouncing around in the back.

Best,

Greg.

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4 hours ago, GJK said:

Diesel doesn't have the same combustion properties as hydraulic oil.  Give me motion sickness over flash burns any time!

In all Warrior variants the fuel tank is in the centre under the turret or cupola, so no-one has to stare at it.  The clear plastic tank was changed to a translucent one around the early/mid 90s (I think) to reduce the motion sickness induced by watching the fuel slosh whilst bouncing around in the back.

Best,

Greg.

 It didn't work it was still a puke generator.

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8 hours ago, Wobbly Head said:

 It didn't work it was still a puke generator.

Can't say that matches my experience.

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17 hours ago, GJK said:

Diesel doesn't have the same combustion properties as hydraulic oil.  

You might read this to resolve any mythology questions one might have.
https://apps.dtic.mil/dtic/tr/fulltext/u2/a212596.pdf

And you're right, Diesel doesn't have the same combustion properties as OHT (the hydraulic fluid used with M60s in 1973).  DF2 has a minimum flash point of 52C, that of OHT is 82C.

For more light reading: https://apps.dtic.mil/dtic/tr/fulltext/u2/a019775.pdf

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17 hours ago, DKTanker said:

You might read this to resolve any mythology questions one might have.
https://apps.dtic.mil/dtic/tr/fulltext/u2/a212596.pdf

And you're right, Diesel doesn't have the same combustion properties as OHT (the hydraulic fluid used with M60s in 1973).  DF2 has a minimum flash point of 52C, that of OHT is 82C.

For more light reading: https://apps.dtic.mil/dtic/tr/fulltext/u2/a019775.pdf

No mythology.

My point (badly made I grant you), was diesel leaking from a fuel tank at atmospheric pressure is one thing, but oil escaping from a pressurised system in a confined space with people in close proximity is another.

I am well aware from my job that diesel presents a fire hazard contrary to what is often assumed.  Only this week I have been reviewing an initial report into an accident where diesel fuel leaked onto hot engine components and caused a fire.

Best,

Greg.

Edited by GJK
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On 4/21/2021 at 12:00 PM, bojan said:

Why not non-transparent fuel tank?

No idea.

I used to sit on an aluminium fuel tank in a Spartan, could easily have used something similar in Warrior.

Best,

Greg.

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In that case you leave 5cm wide window in the tank, no need for entire thing to be transparent.

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13 minutes ago, bojan said:

In that case you leave 5cm wide window in the tank, no need for entire thing to be transparent.

 Most British AFV's with metal fuel tanks had the fuel in rubber bladders so that wouldn't work. My guess is cost if there is a way to do something the MOD will pick the cheapest.

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True, the MoD can scrimp with the best government departments.  Trouble is the end up saving a penny today to spend a pound tomorrow.

I know Scorpion and Scimitar have fuel bladders, but they are not in tanks like Spartan, just a compartment at the rear of the hull.

Best,

Greg.

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