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I'm currently building a Boeing 727 model and was wondering if anyone could tell me what the small, triangular outlet 'flap' is on the underside just forward of the air stairs ?

It appears to be ram operated and is in the down position on all of the ground photos that I've seen.

Thanks

Do you mean the Cooper vane? If it's this one, it's for preventing opening of the rear airstair while in flight... which in turn prevents escapes such as the one D.B. Cooper did after his hijack.

5 minutes ago, Luis Hernandez said:

Do you mean the Cooper vane? If it's this one, it's for preventing opening of the rear airstair while in flight... which in turn prevents escapes such as the one D.B. Cooper did after his hijack.

No, it's not the Copper Vain - this is far larger.

It's difficult to find a very good image, but the second picture in this article about the Cooper Vain shows it off pretty well - just forward of the hinge point for the rear stairs.

Regards

Ah, now I understand. You're talking about the tail skid:

 

See it in use:

Edited March 14, 20215 yr by Luis Hernandez

7 minutes ago, Luis Hernandez said:

Ah, now I understand. You're talking about the tail skid:

 

See it in use:

Yes, that's the one - awesome second picture !

I'm guessing that it was deployed all the time that the a/c was on the ground as it seems to be visible in all of the ground pictures that I've seen ?

Many thanks for your help !

Regards

IIRC, it was down whenever the gear was down.

Technically it is actually part of the landing gear, so yup, it dropped whenever the gear came down to protect against tail strike damage on an over rotation or too much flare on landing although you can see from the dramatic pic posted above that you'd really have to get the nose high to have it touch the ground. 

If you are looking for a good technical book about the 727, I can recommend this one. It's a bit pricey these days because I think it's out of print, but it's excellent and it's a very big book (I just checked my copy and it's 580-something pages). It has diagrams and performance charts for pretty much everything you'd ever need for a real 727, plus it tells you exactly how to fly it and if you like the 727 it's an interesting read as well. I used it years ago for my Avsim review of the Captain Sim 727 and it was invaluable for that because it enabled me to really put that add-on through its paces and learn that about the only thing which was off on that particular flight sim add-on, was some of the EPRs for take off settings because they used one engine modeling system for the three different variants you got in the add-on.