Spitfire undercarriage question.

[Synthetic]

I know Spitfire u/c did not retract symetrically, but can anyone tell me whether it was actually sequenced and if so, which wheel started to retract first?

Thanks in advance

[MacBoero]

The Spitfire undercarriage was hydraulic, and I suspect there was one pump driving the rams in each leg through a common circuit. Manufacturing tolerances will ensure that the ram on one leg will have less friction than the other, and will move first. I don't think any asymmetry in operation was by design.

Interesting to know that the earliest Spitfires didn't have a powered hydraulic pump, the pilot had to fly with his left hand and hand pump the gear with his right!

[Siguarda al fine]

The DC-3 MLG retracts in the same manner as its run off one pump and its usually the leg nearest the pump in use (it has two but only one is in use at a time) that retracts first. FYI the MLG on the Spit blocked the airflow to the radiator so it was important to retract the MLG quickly after take off.

[DeepestSouth]

I have a copy of AP1565B (1943) for the Spitfire Mk II A & B - which includes the maintenance notes. Sect 4 Chap Fig 5 shows a schematic of the hydraulic system. It has a single, engine driven, pump which acts directly on the two main undercarriage jacks through the undercarriage control unit in the cockpit. Neitther there or in the flying notes is there any mention of sequencing, nor in the ground test schedule which goes in to some detail on the checking process. Hope that helps. You could always ask a current Spitfire operator - the BBMF perhaps?

[stevef]

That must have been a C47A, Siguarda!
The later DC3/C47B main hydraulic system is operated by two engine-driven pumps but dependent on the EDP selector, the left engine supplies the autopilot and the right engine supplies the main system. Obviously, the 'both' selection would be made for take off & landing.

[Nopax,thanx]

We're an operator.....one MkV and an XIV; there is no sequencing, just one pump and two legs. If there is a retractable tail wheel that will go first. The pump is on the right hand side and it's usually the right leg that raises before the left one.

[barit1]

Asymmetric retraction - not unusual in most types. The Harvard/Texan usually behaved this way, for the same reason MacBoero cites.

Only when a single actuator/motor drives both MLG is the retraction likely to be symmetrical.