Moderators: richierich, ua900, PanAm_DC10, hOMSaR

 
convair880mfan
Topic Author
Posts: 324
Joined: Fri Jun 25, 2021 12:33 am

Curvature of PW JT8D engine assembly?

Sat Jan 08, 2022 5:51 pm

Does anyone know why there is curvature in the Pratt and Whitney JT8D powerplant? Looks as though the gas flow does now follow a straight through path. Also seems like the curvature originates in the afterbody behind the core engine.



 
User avatar
Starlionblue
Posts: 21060
Joined: Fri Feb 27, 2004 9:54 pm

Re: Curvature of PW JT8D engine assembly?

Sun Jan 09, 2022 1:55 am

Just a guess but it could have something to do with aligning to the local airflow. If you look at an 727 from above, or indeed at a DC-9/MD-80, you can see how the engines are not parallel to the midline, and even curve a bit to follow the fuselage.

Image
 
Dalmd88
Posts: 3243
Joined: Fri Jul 28, 2000 3:19 am

Re: Curvature of PW JT8D engine assembly?

Sun Jan 09, 2022 3:16 am

It has to do with what you are calling the engine. Looking at the first pic of the engine on the trailer, the true engine is sitting directly above the trailer. Every part that is hanging fore or aft of the ends of the trailer are just inlet or exhaust ducts and the thrust reverser.

With a bare JT8D if you put a level on the front flange (were the inlet mounts) of the engine and the rear flange (the ring above the trailer wheels) , you would find them to be parallel.
 
convair880mfan
Topic Author
Posts: 324
Joined: Fri Jun 25, 2021 12:33 am

Re: Curvature of PW JT8D engine assembly?

Sun Jan 09, 2022 4:25 am

Those explanations make sense to me. Thanks so much. Here is a photo of a fuselage mounted JT8D. It seems that the engine is canted slightly downward from front to back including the intake duct but that the rear duct [after the turbine section] cants upwards. Perhaps this is an optical illusion. I am not referring to the part of the center JT8D engine in the same photo. Can't tell for sure.

 
Clydenairways
Posts: 1448
Joined: Thu Jan 11, 2007 8:27 am

Re: Curvature of PW JT8D engine assembly?

Wed Jan 12, 2022 4:35 pm

The first post is a pic of a 737-200 engine which was subject to a design change after the 737-100 went into service. The exhaust pipe and reverser type was originally under the wing, but this needed to get modified due to problems in service with the reverse thrust causing the weight on the main wheels to lift up and reduce braking effectiveness.
The modification by adding a long pipe aft of the wing and the DC9 style buckets was the remedy for this, but i guess they needed to angle the new additional pipe in order to achieve this.

As far as im concerned the DC-9 and 727 JT8's look fairly straight and much shorter in comparison.

If you look at pics of very early 737's you can see the original engine layout.

Who is online

Users browsing this forum: Gillbilly and 11 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos