pilotpip
Posts: 2820
Joined: Fri Sep 19, 2003 3:26 pm

DC-8s And No APU

Wed Mar 10, 2004 6:04 pm

I think this may have been discussed in the past, but why don't DC-8s have APUs? I would even offer this up for any UPS guys out there as the 8s they fly have the CFM-56s and EFIS. What other notable jets didn't come equipped with APUs?

Thanks in advance.
DMI
 
Guest

RE: DC-8s And No APU

Wed Mar 10, 2004 6:14 pm

Notable jets, without APUs... besides the DC8 were -
B-707 B-720, Comet, Caravelle, CV880/990, and the ones that I forgot  Big grin
xxx
The philophy was that initially, all these airplanes operated from well equipped airports... lighter airplane...
The 707/720s, DC8s, CV880/990 required a 115V AC ext power cart...
They needed an air cart for air conditioning and engine start...
The Comets and Caravelles required a 28V DC ext power cart, and 115V DC for start, air conditioning unit cart.
xxx
Happy contrails -
(s) Skipper
 
VC-10
Posts: 3546
Joined: Tue Oct 26, 1999 11:34 am

RE: DC-8s And No APU

Wed Mar 10, 2004 7:24 pm

Some DC-8's had APU's. I've seen UPS '8's with a large hole blanked off just aft of the RH trailing edge which the UPS guys told me was where the APU was fitted in an earlier life.

I think it would be fair to say that any a/c built before 1962 didn't have an APU as standard.
 
Guest

RE: DC-8s And No APU

Wed Mar 10, 2004 8:31 pm

Dear VC-10 - that is correct, a few DC8s and I think 707s were fitted with APU but these were private airplanes, i.e. DC8-72 operated by Aramco I think...
These APUs were fitted much later... in the 1980s I guess.
xxx
By the way, I dont think that VC-10s had APUs, am I right?
xxx
Happy contrails  Smile
(s) Skipper
 
broke
Posts: 1299
Joined: Wed Apr 24, 2002 8:04 pm

RE: DC-8s And No APU

Wed Mar 10, 2004 9:02 pm

In the early days of commercial jets, APU's were not installed. It was probably a combination of a lack of suitable units and an unperceived need which added weight and complexity of these systems.
Once jets were developed that could operate out of smaller airports without the facilities the major airport have, a sales feature was the ability of the airplane to be self-sufficient of any outside assistance for air conditioning, electrical power, and engine starting. Then APU's became the standard.
Most APU's are installed in the tail cone or, in the case of trimotors, under the center engine. The 727 is the exception to this rule, because it was not originally planned to have an APU. The APU on the 727 straddles the main landing gear wheel wells in a metal cocoon. The intake is on the unit and the exhaust is out the top of the right wing. Originally there was a door that was open when the unit was running, but the door had reliability problems and so now there is a grill of cascade vanes that deflect the exhaust away from the fuselage. Occasionally, the APU will "torch" on start up and if there are passengers on board when that happens, pandemonium can occur, as the impression is that the airplane is on fire.
Some DC-8's were retrofitted with a dual APU installation in the aft end of the lower forward cargo compartment. From what I've heard the system was not too reliable and there was a problem with overheating of the compartment causing the units to auto-shutdown. So they were removed.
 
pilotpip
Posts: 2820
Joined: Fri Sep 19, 2003 3:26 pm

RE: DC-8s And No APU

Wed Mar 10, 2004 11:00 pm

Thanks everybody!

One of the neat things about my job is the fact that I get to see a bunch of old iorn that is no longer seen carrying pax in the developed world. One of the bad things about this, is fueling while hearing that 727's APU blasting away 10 feet from me. This does, of course, give a little added warmth in the winter  Big thumbs up

But then again, I can't stand that whining sound that huffers(airstart carts) make.
DMI
 
VC-10
Posts: 3546
Joined: Tue Oct 26, 1999 11:34 am

RE: DC-8s And No APU

Wed Mar 10, 2004 11:19 pm

Generally the VC10 didn't have APU's, they had 3 HP air bottles in the tailcone, directly under the rudder, in case there was no airstart truck was available. The air was used to ignite kerosene in a 'combustor' the exhaust gases of which were then directed to the air starter turbine.

The original RAF '10's were delivered with Artouste APU's and the ex-airline VC10's the RAF took were retro fitted with APU's.

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