lmml 14/32
Posts: 2358
Joined: Tue Jan 30, 2001 2:27 am

B733 Reversers

Tue Jun 04, 2002 5:22 pm

Question: When the B733 reversers are applied is it just the bypass air that is blocked?
 
Buzz
Posts: 694
Joined: Sun Nov 21, 1999 11:44 pm

RE: B733 Reversers

Tue Jun 04, 2002 10:37 pm

Hi Lmml 14-32 (wonder what runway that is?) Buzz here. You're right, on the "super guppy" only the fan airflow is blocked. Seems that the turbine airflow is more trouble than it's worth.

On the Classic 747 and DC-10 we deactivated the turbine (core, hot section) reversers 20 years ago. They would often get a bunch of cooked turbine oil in them an jam anyway. And there was enough reverse thurst available from the fan to do the job.

g'day
Buzz Fuselsausage: Line Mechanic by night, DC-3 Crew chief by choice
 
lmml 14/32
Posts: 2358
Joined: Tue Jan 30, 2001 2:27 am

RE: B733 Reversers

Wed Jun 05, 2002 4:26 pm

This means that as the thrust is reversed in the bypass area the combusted area is still producing forward thrust. Does not make much sense. There must be another explanation.

LMML 14/32 = MALTA (MLA) N35 E14
 
KFRG
Posts: 353
Joined: Mon Mar 04, 2002 10:37 am

RE: B733 Reversers

Wed Jun 05, 2002 8:59 pm

LMML 14/32,
To activate TR, the fan's must be at idle.

-Tommy
 
bio15
Posts: 1048
Joined: Fri Mar 23, 2001 8:10 am

RE: B733 Reversers

Thu Jun 06, 2002 2:21 am

There's not another explanation. Turbofan engines, opposite to turbojets, have a high bypass ratio (8:1 or so) which means almost 8 times as much air passing through combustion is bypass air. Turbofans generate most of their thrust with the 'cold air' rather than with the 'hot air', so it is adequate to use the bypass air for reverse thrust. On 'bucket' type reversers the whole thrust is diverted.

On the 737-200 (although I believe these are torbojets)

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On the 717-200

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-bio
 
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wilcharl
Posts: 1164
Joined: Sun Jun 25, 2000 11:19 am

RE: B733 Reversers

Thu Jun 06, 2002 2:55 am

The pratts on the 737 are turbofans.. not high bypass turbofans like the BR-715 but still a turbofan none the less
 
lmml 14/32
Posts: 2358
Joined: Tue Jan 30, 2001 2:27 am

RE: B733 Reversers

Thu Jun 06, 2002 6:40 pm

Wow ! As much as 8 times as much bypass air. Amazing. In that case what Buzz said comes into perspective. This begs another question. Does reverse thrust operate all stages of the engine?
 
NKP S2
Posts: 1665
Joined: Mon Dec 20, 1999 3:16 am

RE: B733 Reversers

Fri Jun 07, 2002 1:59 am

I'm not completely sure of your "all stages" reference. But yes, the engine core's internal gaspath is unchanged during use of T/R's. As has been said, it is only fan air that is blocked and directed fwd through cascade vanes.

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