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Gulfstream Engine Spool-up Time Question

Posted: Sun Oct 03, 2010 11:08 pm
by queb
On page 19 of this document, it is mentioned that some Gulfstream aircraft have an engine “spool-up” time longer than most transport category jet aircraft. Between 8 and 30 seconds. Here is the text (p. 19):

Quote:
The JOEB found only one Special Flight Characteristic; the engine “spool-up” time is longer than most transport category jet aircraft. It can range from 8 seconds at sea level to 30 seconds at altitude to move from idle thrust to maximum continuous thrust. At low altitude e.g. circling, the spool-up time will be considerably longer than 8 seconds if Flaps are -flight briefing, highlighting engine spool-up times, is accomplished prior to conducting training or checking in the following areas: stalls, touch-and-go landings and simulated one-engine inoperative manoeuvres.

Flight crew must be made aware of the risks during a go-around from an LNAV/VNAV approach. The danger is related to the requirement to set an altitude below actual aircraft altitude during the final approach. Until such time as modifications are made so that the altitude selector setting procedures are similar to procedures used during an ILS approach, LNAV/VNAV approaches to a go-around must stress FMA awareness and the requirement to reset the altitude selector, after the go-around has been initiated, to the go-around altitude.


https://www.easa.europa.eu/ws_prod/c/doc/final%20reports/Gulfstream/GV,GV-SP,GIV-X%20JOEB%20Report.pdf

Is this an engine issue ?

[Edited 2010-10-03 16:10:48]

[Edited 2010-10-03 16:11:05]

RE: Gulfstream Engine Spool-up Time Question

Posted: Mon Oct 04, 2010 2:41 am
by 411A
Limited to the RR Spey powered models, as these engines are not of the turbofan variety.
Having said this, the Spey spools up much faster than the 'ole JT4A did on the 707.

RE: Gulfstream Engine Spool-up Time Question

Posted: Mon Oct 04, 2010 2:49 am
by 2H4
Quoting 411A (Reply 1):
the Spey spools up much faster than the 'ole JT4A did on the 707.

About how long did it take the JT4A to get from flight idle to go-around thrust?

RE: Gulfstream Engine Spool-up Time Question

Posted: Mon Oct 04, 2010 2:55 am
by bohica
Quoting 411A (Reply 1):
Limited to the RR Spey powered models

The RR Spey was also on the Trident, BAC-111, and the F-28. Did these planes experience the same spool-up issues?

RE: Gulfstream Engine Spool-up Time Question

Posted: Mon Oct 04, 2010 3:21 am
by DashTrash
Quoting 411A (Reply 1):
Limited to the RR Spey powered models, as these engines are not of the turbofan variety.

Speys are turbofans, just VERY low bypass.

RE: Gulfstream Engine Spool-up Time Question

Posted: Mon Oct 04, 2010 4:04 am
by 411A
Quoting 2H4 (Reply 2):
About how long did it take the JT4A to get from flight idle to go-around thrust?

16 to 18 seconds.
This is why the airplane needed to be flown carefully so as to not un-spool the engines whilst on approach for landing.
So-called 'slam-dunk' approaches were simply not possibe, to be done safely.
This changed with the fan-powered varients, especially the advanced cowl models.

RE: Gulfstream Engine Spool-up Time Question

Posted: Mon Oct 04, 2010 4:19 am
by 2H4
Quoting 411A (Reply 5):

Interesting, thanks.

RE: Gulfstream Engine Spool-up Time Question

Posted: Wed Oct 06, 2010 2:49 am
by queb
thanks for your responses