Question about the Boeing 707…

http://www.airliners.net/open.file/0581574/L/

Could anybody explain this?

If you read the reamrks below this picture, it says: “Have a look at the outer pylon – it has no turbocompressors used for air conditioning. No 707’s came with 4 TC’s – no 1 engine has a slightly different look.”

This article aimed at modellers has lots of information on the variations as between the different 707 and 720 versions.

http://www.airlinercafe.com/page.php?id=72

Thanks for the info guys 🙂

The little inlets above some/all of the engines are for the engine driven compressors that pressurise the plane etc. The number of them depends on the model 707/720.

707-300 models with the P&W engines generally have 3 on engines 2,3 & 4 – hence engine 1 has a different ‘simpler’ pylon.

720 models have 2 only, on the inner engines.

707-400 models have the RR-Conway engines have them on all 4 engines – but these seem smaller and more blended into the general shape of the pylon.

Modern jets use air taken directly from the engine compressors to provide air conditioning & pressurisation. The older jets, particularly the 707 & DC8 used independent compressors to provide this air, although they were themselves driven by air taken from the engines. On the DC8 they are mounted in the forward fuselage hence the chin intakes underneath the radome. On the 707/720 they are mounted on top of the engines forward of the pylons. Depending on model there are two or three of them, number one engine never has one number four does sometimes.
Hope this helps.

Simon.

Looks like some of the pylons have some sort of air intake, whilst the others don’t.

Just a guess though.

1L.