Open Canopy Flight - Spitfire, P-40, P-51

[MkIV Hvd]

I'm wondering if there is a speed limit on open canopy flight with any of these three? If it's in the manuals, I've missed it

Thanks in advance!

Cheers,
Rob

[Jacques]

Hi Rob, in the tiny and hard-to-see script of a mkIIa and b manual is the note that:

“the hood can be locked either closed or open, but not any other position“...air pressure at high speed tends to keep the hood forward and it becomes very difficult to open in a dive. Then there is the caution...”Great care is necessary to avoid getting the arm out in the airflow when opening it at high airspeed (over about 140 mph A.S.I. The arm could easily be dislocated at high speed.”

So the manual seems to be saying that you can...but it isn’t necessarily advised unless you really need it open.

[ratty]

The same (?) manual, Section 2, Handling and Flying Notes, lists these vital actions after taking off:

Make sure you're up
Raise the gear as you accelerate to 140 mph
Start a gradual climb, adjusting the throttle to the rated position and set pitch control to give 2,850 r.p.m.
Continue to accelerate to 185 m.p.h.

Then subsequent actions, which "may be performed at leisure, though without undue delay", are:

Observe oil pressure
And finally: "Fully close the emergency exit door and then close the cockpit hood."

So apparently even the door is good to more than 185 mph. In the Approach and Landing section the book says "Open and lock back the cockpit hood" without any mention of speed. I've looked around and found next to nothing elsewhere about canopy speeds. I have learned that early US Navy jets (Banshee, Cutlass, et al.) were landed with the canopy open, but then I've also seen suggestions that the FW190's canopy would depart the plane if opened at flying speed.

[Killratio]

Undercarriage extension speed in the Spitfire is 160mph and the drill is to open the hood before lowering that. Climb out has been detailed above by ratty.

If I recall my discusions with Dudley correctly, the maximum practical limit is 200mph for the P-51 and should be about the same for the Spitfire. This is not to say that life would be anything like pleasant at that speed. You wouldn't be sticking your head out!! You will also, of course, vacuum out every bit of dust in the cockpit, straight into your face at high speeds.

[MkIV Hvd]

That's awesome guys, thanks for the replies all!

Apparently I didn't read the Spit manual carefully enough and that all makes perfect sense. I think the question arose while doing circuits and wondering about a possible speed restriction on downwind with the canopy open.

It just occurred to me that on a deeper level, the question was lurking because I lost the right side canopy glass in our Harvard while doing a low pass at Claresholm, AB many years ago. It was a very hot day and I had the canopy cracked to the first notch and while on the final part of a pretty steep final approach for the pass I was distracted by a quick movement in my right side peripheral vision which drew my attention. It took a brief second to realise the glass had blown out...when I snapped my attention back forward the ground was coming at a great rate and it took a heart stopping pull to miss it...yikes...

On the way back to Calgary I was having recurring thoughts about the news story that would have been ... about a Transport Category pilot who flew a Harvard directly into the ground for no discernible reason...it makes me kind of emotional even now...

There was no damage to the airplane other than the black rubber mark where the window/emergency exit weather stripping hit the horizontal stabilizer. In afterthought I figured it was likely a bit of adverse yaw at the higher speed of the roll-in that sucked it out. I don't think it would have happened with the canopy fully opened, but we'll never know. Mental note was filed: canopy fully CLOSED for anything other than straight and level (more or less) flight.

Cheers,
Rob

[ratty]

That's even a mildly heart-stopping story, Rob. A fine example of how the most unlikely things can be out to get you in the air.

In response to Killratio's "vacuum out every bit of dust in the cockpit, straight into your face at high speeds", I thought it was funny that the full Pilot's Notes Preliminary approach section reads:

(i) Open and lock back the canopy hood.
(ii) Ensure that the mixture control is back to NORMAL.
(iii) Stow maps.

Clearly (iii) assumes they're still in there.

[MkIV Hvd]

Hahaha right ratty! It seems the order should maybe be adjusted to put that first!
Either way, it's the kind of thing that you'd only do once I bet...

[Scott - A2A]

I'm wondering if there is a speed limit on open canopy flight with any of these three? If it's in the manuals, I've missed it

Thanks in advance!

Cheers,
Rob

Good question, we don't actually model a max speed but I can imagine it would get quite ugly if you did exceed a max speed. The added drag of the open canopy should help a tad to keep speeds down however.

Scott