View Full Version : Jet canopy - distorted vision?


Trim Stab
18th May 2012, 08:13
I was surprised to read in this article that the FIA had rejected fitting F1 cars with fighter aircraft canopies because they would give "distorted vision".

I believe the trials were carried out on an F16 canopy. Any comments?

BBC Sport - F1 head protection 'inevitable' (http://www.bbc.co.uk/sport/0/formula1/18104886)



Geehovah
18th May 2012, 11:02
The view from an F4 was shocking in places. From the back it was particularly bad as the canopy curved inwards towards the arch. That led to both distortion and reflections. It was ten times worse when a scratch was blended out leaving a round coke bottle bottom in the canopy.

Pontius Navigator
18th May 2012, 11:44
They used to take astro shots using a bubble sextant in the Canberra. The canopy was calibrated to allow for the distortion. Similarly all astro domes had a correction card.

It follows that any transparency will have some distortions. Presumably in F1 at high speeds and very close proximity that would be highly significant.

Manandboy
18th May 2012, 12:55
If it's going to be thick enough to protect F1 drivers from flying debris at 200 mph, there will be an optical impact - introducing curves to perspex and, to a slightly lesser extent, polycarbonate, will produce some distortion. In general, the more you pay the less the degradation, but there will also, inevitably, be a light attenuation issue whether or not the canopy is curved.

F1 drivers are bound to be sensitive about any apparent adverse effect on visual acuity - do they need to be? It depends how safety vs potential minor visual degradation is rated. After all, we managed cross-cockpit formation in the JP (dreadful), the Hunter T7 (much worse) and night rear seat landings in the Tornado (appalling). However, in F1 cars at closing speeds even the Buccaneer airbrake couldn't cope with, I might be a bit hesitant about another potential distraction as well.

Fox3WheresMyBanana
18th May 2012, 13:06
Note the head restraints now used in F1. They don't, nor are able to, move their heads around as much as fighter pilots.

garyscott
18th May 2012, 14:03
Im sure i was told that Viper canopies are all slightly, optically different. When calibrating the HUD, the angle of difference between conpy up (boresighting an object near horizon) and then sighting same object canopy down, can differ by up to 6 degrees. This has to be taken into effect when collimating.

I will endeavor to find the refference and link it here.

davejb
18th May 2012, 20:28
It might also help to remember that F1 drivers have to position their cars within inches of the ideal spot at high speed - watch
F1 1991 Spain Nigel Mansell overtakes Ayrton Senna - YouTube

and I think it's obvious why any distortion is too much.

Tiger_mate
18th May 2012, 20:30
Helmet visors are far from optically perfect never mind the canopy.

Trim Stab
18th May 2012, 20:39
So why do the RAF insist on 20/20 vision without astigmitism? Seems like they could have let Marty Feldman join and it would all have been just fine.

Sleeve Wing
18th May 2012, 20:59
Interesting thread, this.
I fly an Extra 300 civvy advanced aeros aircraft these days.
These are fitted with a comparatively large (tandem 2 seat) canopy.
In my experience they have minimal optical defects and this from soloing in the rear seat.
The downside is that for every 6 canopies produced, 4-5 are scrapped for optical distortion. This gives a price tag for a replacement of around 10,000 !