Visual System: Outside Views with Beamers

For more than 10 years I had used three 21" CRT monitors to display the outside view. I started with 3 networked PC's (each running a copy of FS9 and WideView). They displayed a synchronized outside view on 3 monitors. Later I moved to a single SLI-PC with two video cards, driving all 3 monitors. Details on these setups are available here.

In mid-2007, with high quality video projectors finally entering an acceptable price range, I decided to upgrade the outside view of my cockpit with 3 beamers, driven by 1 PC and a Matrox TrippleHead2Go. After some research, I choose the BenQ-721c business presentation beamer. It's DDR-DLP chip produces a very crisp image with good contrasts. In economic mode it's lamp lasts 4.000h, resulting in operating cost of only 6 €-Cents /h. Last but not least it is small, light and it can be ceiling mounted.

What follows is a short description of how I installed the new system and an attempt to describe the experience of flying with "the big picture".

 

First things first... there is no way to attempt the installation of three beamers in a limited space without some planning. I made a scale drawing of my simulator room and all furniture it it, and of course of the cockpit itself. I added the position of the window and heaters and even the opening arch of the door. It immediately became clear: this was going to be a tight fit!

But my drawing also showed that I could achieve a whopping 126cm x 95cm (4 x 3 ft) per screen! Screens of these precise dimensions are not available (or would be very costly to order), so I decided to build them myself. The screens would be fixed to four 40 x 40mm wooden beams and be detachable, so allow - albeit slightly restricted - access to the furniture behind them.

The TH2G outputs one single FS9 window, distributed over three screens. FS9 has a minimum zoom setting of 0.31, that produces a simulated field of view (FoV) of 109 degrees. Each screen is set up at the same distance from the pilot. Together, they produce a physical FoV of 108 degrees - close enough to the FoV that FS9 delivers at the 0.31 zoom setting.

An important consideration during planning it the projector's throw. In other words: What distance between lens and screen is required to achieve the desired screen diagonal? Luckily, this information can be found on most manufacturer's websites.

So far, so good.

 

The frame for the first screen, made from 20 x 20mm wood battens with plywood reinforcements. I used no glue, so in case of need the screen size can be modified later - you never know what fate holds in store and how big the next place will be...

The frames will later be covered with linen and painted with standard white enamel paint.

Installation of the frames (for easier handling at this point still without textile). The positioning of the support beams is crucial. Even small imprecisions will lead to a distorded image later. I simply applied the measures from my drawings and luckily no further corrections were needed.

I tried to strike a balance between screen size and usability of my room. Greed won and I went for maximum screen size. As a result, my PC workplace is hidden behind the left screen. One of the beams sits right on the surface of the desk. But since the screen is detachable in seconds, the situation is not as bad as it looks on this shot.

The support structure for the three beamers. I wanted a strong, light and non-allergic material, so I choose weapons grade titanium (on second thought though, I went for plywood and my standard 20 x 20mm battens).

This support will be attached to a standard projector ceiling mount, so messy drilling in the ceiling is reduced to a minimum.

One of three projector mounts. They attach to the main support with a 6mm threaded rod, so the projector can easily be rotated into their correct final position.
The completed ceiling mount. The projectors are height adjustable via 3mm threaded rods and can be rotated freely together with their individual mounts. Setting up the correct positions required some adjustments of the threaded rods, but in the end it took less than 20 minutes to have them all aligned.

I must admit that I totally underestimated the time it would take to produce and install these screens. I had hoped it could be done in 2 days, but in the end I needed several weekends.

This shot gives a first idea of what to expect from the new setup: A lot of screen real estate...

 

The first test flight, in a Beech Baron 58 over Ketchikan, Alaska.

What can I say? The experience to fly with a 12 x 3 feet screen is simply mind blowing! There is still no full situational awareness, but it's a quantum leap compared to the use of monitors, even big ones. Now the pilot really has to turn his head left and right to take in all details of the outside world.

I also noticed that the necessity for the eyes to change focus between cockpit and outside view adds greatly to the sensation of actually flying a plane.

A short clip of the checkerboard approach to Kai Tak at dusk in a B737-400. It demonstrates - within limits - what 3 projectors can do for the "suspension of disbelief" that us cockpit builders are seeking so desperately.

Duration: 1:39, Size: 21 MB, Format: MPEG, Resolution: 640 x 480

A change of location in late 2007 allowed the installation of a bigger screen with a total surface of 18 x 5 feet. The screen material is now genuine projection cloth (1,1 grain), and the whole room is painted dark grey. The result is a much higher contrast image at a lower power setting of the projector lamps.

The beamers are mounted directly and individually under the ceiling. Because there is more space between them, they are now all at the exact same altitude. No keystone corrections are required anymore, resulting in a sharper image and more precise alineation of the output from the three projectors.

Last but not least I replaced the analogue Matrox TrippleHead2Go with the digital version. Again, this helped to improve image sharpness and definition.