Sponsor Message:
Aviation Technical / Operations Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
Holes On The Cowlings Of The 747?  
User currently offlineCalAir From United Kingdom, joined Apr 2005, 298 posts, RR: 1
Posted (8 years 5 months 2 weeks 5 days 23 hours ago) and read 4019 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?


View Large View Medium
Click here for bigger photo!

Photo © Shary(Shahram)




British Caledonian...we never forget, you have a choice
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 (8 years 5 months 2 weeks 5 days 21 hours ago) and read 3974 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: 9
Reply 2, posted (8 years 5 months 2 weeks 5 days 20 hours ago) and read 3962 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 (8 years 5 months 2 weeks 5 days 20 hours ago) and read 3949 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: 50
Reply 4, posted (8 years 5 months 2 weeks 5 days 16 hours ago) and read 3912 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, 3701 posts, RR: 34
Reply 5, posted (8 years 5 months 2 weeks 5 days 13 hours ago) and read 3872 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, 31684 posts, RR: 56
Reply 6, posted (8 years 5 months 2 weeks 5 days 12 hours ago) and read 3855 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 (8 years 5 months 2 weeks 5 days 9 hours ago) and read 3812 times:

We used to call them "blow in doors".

User currently offlineDw747400 From United States of America, joined Aug 2001, 1260 posts, RR: 1
Reply 8, posted (8 years 5 months 2 weeks 5 days 8 hours ago) and read 3791 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, 31684 posts, RR: 56
Reply 9, posted (8 years 5 months 2 weeks 5 days 7 hours ago) and read 3769 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, 3701 posts, RR: 34
Reply 10, posted (8 years 5 months 2 weeks 5 days 7 hours ago) and read 3758 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 (8 years 5 months 2 weeks 5 days 7 hours ago) and read 3755 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, 31684 posts, RR: 56
Reply 12, posted (8 years 5 months 2 weeks 5 days 6 hours ago) and read 3747 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, 3701 posts, RR: 34
Reply 13, posted (8 years 5 months 2 weeks 5 days 6 hours ago) and read 3742 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, 31684 posts, RR: 56
Reply 14, posted (8 years 5 months 2 weeks 5 days 6 hours ago) and read 3737 times:

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

Thats correct.
regds
MEL



Think of the brighter side!
Top Of Page
Forum Index

Reply To This Topic Holes On The Cowlings Of The 747?
Username:
No username? Sign up now!
Password: 


Forgot Password? Be reminded.
Remember me on this computer (uses cookies)
  • Tech/Ops related posts only!
  • Not Tech/Ops related? Use the other forums
  • No adverts of any kind. This includes web pages.
  • No hostile language or criticizing of others.
  • Do not post copyright protected material.
  • Use relevant and describing topics.
  • Check if your post already been discussed.
  • Check your spelling!
  • DETAILED RULES
Add Images Add SmiliesPosting Help

Please check your spelling (press "Check Spelling" above)


Similar topics:More similar topics...
Ffrats On The 747-200 posted Sun Nov 28 2004 08:01:37 by NWA
What's This Object On The 747-SP's Wing? posted Mon Feb 9 2004 22:04:40 by Mr Spaceman
Engine Start Sequence On The 747 posted Sat Feb 23 2002 19:23:46 by Rohan737
How Hot Do The Breaks Get On The 747... posted Tue Apr 24 2001 22:27:17 by Tuffty
Engine Nacelle Diffrences On The 747? posted Wed Jan 31 2001 21:32:49 by Ericmetallica
Tri-motor - What's That On The Wing? posted Thu Nov 9 2006 00:50:53 by TimePilot
What Are These Intakes For On The 777? posted Wed Nov 1 2006 04:13:28 by Gh123
The Size Of The 747 Freighter Opening posted Sat Oct 21 2006 11:34:47 by NZ107
Please Help: A Question On The Directional Gyro posted Tue Apr 4 2006 04:09:07 by FLY2HMO
Elevators On The MD-11 posted Fri Mar 3 2006 12:45:42 by Jeffry747

Sponsor Message:
Printer friendly format