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Holes On The Cowlings Of The 747?  
User currently offlineCalAir From United Kingdom, joined Apr 2005, 298 posts, RR: 1
Posted (7 years 1 month 1 week 3 days 2 hours ago) and read 2980 times:

If you look at the photo below, the 747-100 has holes on the engine cowlings, that other early 747 photos I have seen do not, what is their purpose?


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Photo © Shary(Shahram)




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14 replies: All unread, jump to last
 
User currently offlineSfomb67 From United States of America, joined Dec 2005, 417 posts, RR: 0
Reply 1, posted (7 years 1 month 1 week 2 days 23 hours ago) and read 2935 times:

Don't know the technical name for them, but they're spring loaded doors that open under eng acceleration to allow more air into the engine. What that thing behind the APU ? Test equip ?


Not as easy as originally perceived
User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 10
Reply 2, posted (7 years 1 month 1 week 2 days 23 hours ago) and read 2923 times:

Quoting Sfomb67 (Reply 1):
What that thing behind the APU ? Test equip ?

In-flight refueling boom (flying boom).

User currently offlineSpeedracer1407 From United States of America, joined Dec 2004, 333 posts, RR: 0
Reply 3, posted (7 years 1 month 1 week 2 days 22 hours ago) and read 2910 times:

I believe those little doors (whatever they're called) were on the original JT9-D 747 engines, but were later considered unnecessary following a redesign of the intakes.


Dassault Mercure: the plane that has Boeing and Airbus shaking in their boots.
User currently offlineLTU932 From Germany, joined Jan 2006, 13864 posts, RR: 51
Reply 4, posted (7 years 1 month 1 week 2 days 18 hours ago) and read 2873 times:

Quoting Speedracer1407 (Reply 3):
I believe those little doors (whatever they're called) were on the original JT9-D 747 engines, but were later considered unnecessary following a redesign of the intakes.

Those small inlets were also present on the 707 with JT3D turbofans. Those with pure jets and with the Rolls Royce Conway turbofan don't seem to have those smaller inlets.

User currently offlineVC-10 From United Kingdom, joined Oct 1999, 3677 posts, RR: 37
Reply 5, posted (7 years 1 month 1 week 2 days 16 hours ago) and read 2833 times:		 Support Airliners.net - become a First Class Member!

Quoting Sfomb67 (Reply 1):
Don't know the technical name for them

Secondary Inlet Doors

User currently offlineHAWK21M From India, joined Jan 2001, 31201 posts, RR: 58
Reply 6, posted (7 years 1 month 1 week 2 days 15 hours ago) and read 2816 times:

JT9Ds with Blow in Inlet doors/Secondary Inlet Doors.
What would be the Tanker capacity.

regds
MEL


Think of the brighter side!
User currently offlineTropicBird From United States of America, joined May 2005, 502 posts, RR: 0
Reply 7, posted (7 years 1 month 1 week 2 days 12 hours ago) and read 2773 times:

We used to call them "blow in doors".

User currently offlineDw747400 From United States of America, joined Aug 2001, 1244 posts, RR: 1
Reply 8, posted (7 years 1 month 1 week 2 days 10 hours ago) and read 2752 times:

Are they mechnaically actuated or does the airflow force them open under certain circumstances?


CFI--Certfied Freakin Idiot
User currently offlineHAWK21M From India, joined Jan 2001, 31201 posts, RR: 58
Reply 9, posted (7 years 1 month 1 week 2 days 10 hours ago) and read 2730 times:


Quoting Dw747400 (Reply 8):
Are they mechnaically actuated or does the airflow force them open under certain circumstances

The ones on the JT8D powered B737s operate mechanically by Airflow thru them at low RPM.
Presume it would be the same on these too.
regds
MEL

[Edited 2006-04-16 18:59:52]


Think of the brighter side!
User currently offlineVC-10 From United Kingdom, joined Oct 1999, 3677 posts, RR: 37
Reply 10, posted (7 years 1 month 1 week 2 days 9 hours ago) and read 2719 times:		 Support Airliners.net - become a First Class Member!

Quoting HAWK21M (Reply 9):
The ones on the JT8D powered B737s operate mechanically by Airflow thru them at low RPM.

They are spring loaded closed & open by suction at HIGH RPM

User currently offlineCalAir From United Kingdom, joined Apr 2005, 298 posts, RR: 1
Reply 11, posted (7 years 1 month 1 week 2 days 9 hours ago) and read 2716 times:

Cheers guys, wondered why I hadn't seen them before!


British Caledonian...we never forget, you have a choice
User currently offlineHAWK21M From India, joined Jan 2001, 31201 posts, RR: 58
Reply 12, posted (7 years 1 month 1 week 2 days 9 hours ago) and read 2708 times:

Quoting VC-10 (Reply 10):
They are spring loaded closed & open by suction at HIGH RPM

True they are Spring loaded.Wouldn't High RPM/Thrust provide adequate thrust thru the Inlet Duct,not requiring the opening of the blow in doors.
regds
MEL


Think of the brighter side!
User currently offlineVC-10 From United Kingdom, joined Oct 1999, 3677 posts, RR: 37
Reply 13, posted (7 years 1 month 1 week 2 days 9 hours ago) and read 2703 times:		 Support Airliners.net - become a First Class Member!

They open at high RPM - low forward airspeed.

When I was involved in 707 Eng Runs they woul be 'cracked' open at idle & fully open by 'part power'

User currently offlineHAWK21M From India, joined Jan 2001, 31201 posts, RR: 58
Reply 14, posted (7 years 1 month 1 week 2 days 9 hours ago) and read 2698 times:

Quoting VC-10 (Reply 13):
They open at high RPM - low forward airspeed

Thats correct.
regds
MEL


Think of the brighter side!
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