[flaps]

Dragon says this :

However, what makes this item even more appealing is the detailed diorama base featuring a compass platform, this being a ramp designed to raise the tail of the aircraft to allow the fighter’s machine guns to be test-fired and calibrated on the ground. The accurately designed fighter mounted on a scenic base is very realistic in appearance, and the combination makes an ideal centerpiece for any model aircraft collection.

A friend of mine says this is completely wrong and the real story is this :

A compass-base is/was used to calibrate the aircrafts compass, not the guns. Harmonising the guns, gunsight and camera was done at the firing-butts.



So which is it?

Flaps

[hworth18]

My understanding is that the Compass base was to calibrate the aircraft compass and other direction finding equipment.

[Hoverbug]

All magnetic compasses need to be regularly "swung" - i.e. their variation determined with electrical components powered up. This is still done with aircraft today, though with simple "whiskey" compasses, leveling them out is not required as was the case with the aperiodic compasses mounted horizontally. There are VOR checkpoints at airfields for checking out "electronic equipment", but the leveling out business was all about the compass.

[Andrew]

I thought that compass base would be a bit big/unwieldy and impractical to use to harmonise guns. They didn't have one of those on EVERY airfield did they?

[Hoverbug]

Originally Posted by Andrew

I thought that compass base would be a bit big/unwieldy and impractical to use to harmonise guns. They didn't have one of those on EVERY airfield did they?

It's a depot-level maintenance type deal - i.e. rear echelon. If the plane didn't get it done in the appropriate time frame, it wasn't necessarily a critical issue in the short term.

[jim]

A poor photo but it shows the gun aligning technique.

[Hoverbug]

I'm sure many compasses were "swung" using the same tactic - i.e. simply raising the tail at cardinal points on the compass. The "platform" would have been a labor-saving device - hardly a critical piece of equipment. Again, something found at a large rear-echelon airfields.