why does the Antonov wait 4 minutes with engines at 50% before take off?

[Vulcan607]

evening,

just as the title asks - can anyone explain why the Antonov (ruslan) wait 4 minutes on the runway with engines at 50% prior to dept?

surely this must be a pain for guys in ATC?

[Chilli Monster]

Don't know but would like to.

However - from an ATC point of view it's not that much of a problem. As we're expecting it then it can be planned around.

[NudgingSteel]

I believe that they have had problems in the past with certain engines like those fitted to the An124, when the engine has run up to full power and then kept going (ie spinning faster and faster until it disintegrates), as whatever was supposed to stop it "overspeeding", didn't. The theory now is that if all engines stabilise at high power for several minutes before departure, all is well. If not, better to be sitting on the runway when it goes wrong!
That is the story I've heard, anyway, so I'd like to hear confirmation from someone who knows.

Like Chilli says, it's not a problem if you can plan for it (and not line an An124/225 up in a 6-mile gap and expect to get away with it!)

[Pugilistic Animus]

Off Topic a bit:

but how many donks can the 225 lose
1. on TO?
2. Enroute---3 out on same side? four out???

same query in regards to the B52?

these questions have bothered me a long while now

PA

[Dash7Ace]

Maybe the folk up the pointy end, are having a few 'shots of the white thingy' before takeoff.. hence the 4 mins
1 min to open bottle
1 min to pour and serve
1 min to down it, and
1 min to burp
yes, just about right, I would assume

[doubleu-anker]

The AN 124 being of advanced design, needs 2 F/E's to "trim" the engines for 5 minutes before t/o.

[411A]

...needs 2 F/E's to "trim" the engines for 5 minutes before t/o.

Sort of like a big RR Dart...

[Capt Claret]

It's my understanding that some of the Russian turbines need a slow run to power to allow internal seals to seal properly. I guess Russian seals aren't as capable as US/European seals.

[forget]

I guess Russian seals aren't as capable as US/European seals.

So you don't need any seals in Space?

[Skipness One Echo]

No the fish to feed them screws the payload..... now Pigs in Space is a different matter entirely

[sengasengana]

This is mostly to let engines' thermal variations to even out, before going full thrust on take-off.

Due to East's less sophisticated engine materials, this enhances engine durability. The same goes with thrust reductions in flight as well, ref "shock cooling" of big piston engines of the same era.

ss

[Engineer]

concur what sengasengana states if you were to advance the throttles to takeoff power like a GE or P&W chances are that the runway would be littered with engine parts.

Remember at Kuwait on the AN124 sitting at the end of the runway waiting the prescribed time period for the engines to stabilise and an Air France aircraft on finals. After take off heard the AF crew complaining that the sand storm created had almost reduced the visibility to below CATI standard

[galaxy flyer]

Early C5 era did something like it for 2 minutes for the same reason, thermal stability. We stopped it before I got there in 88. The old FEs called it 'cooking the engines'.

GF

[Spitoon]

I believe it is also something to do with ensuring good oil temps and flow but maybe this is only in low temps.

[Fark'n'ell]

now Pigs in Space is a different matter entirely

Nice one Skip(or should I say Miss Piggy)

[WindSheer]

Doing a crew headcount maybe..?
Skipper.....'here'.........fo.....'here.......fe1....'here'. .......