R

Reheat

Active Member
? ever since I finished my 8 I have been thinking that it needed a combining glass on the glare shield to finish it off. A gun sight reticle or some type of HUD. It?s been done. One guy made one to fit over his Dynon, but the display was washed out on a sunny day (that thread is here somewhere), and another put some semi-reflective film on his windscreen to reflect his sport AOA. Another put an iron sight on his Hat-in-the-Ring 8?cool. These were inspirational. A little research and optics review revealed that a simple Reflex sight system consisted of a light source, front surfaced mirror, collimating lens and a partial mirror or combining glass (beam splitter). The best light source I could come up with was LED?s (bright ones). Some systems use lasers, but that is out of my league. The Front (or First) Surfaced mirror was easy to come by from several sources. Next was a lens to focus to infinity. The lens type needed to be a plano-convex (PCX) or double convex (DCX) with the plano-convex being preferred (less aberration). It should be noted here that the BIG BOYS use a complex lens system so that distortion near the edges and other optic anomalies are corrected. I tried a few including some Fresnel lenses and finally found a 77mm PCX with a 200mm focal length that seems to work. In order to focus to infinity put the light source at the focal length from the flat side of the lens and the beam will come out parallel (collimated) out the other side. Ya sure, you betcha! I found a good source for the combining glass. They make a partial mirror they call a ?Teleprompter Mirror? and they will make it in custom sizes and reflectivity. I used one that reflects 60% and passes 40% to work in the sunlight. These are made of acrylic and not glass (you can cut em with your dremel tool). For ease of construction my ?prototype? is made out of project board and hot melt glue. I am using my ZAON collision avoidance to display on the combining glass. I?d like to add my GRT master warning light and my Aux Fuel Pump light via LED repeaters. Whatever, put what you want including a gunsight reticle out of LEDs to aim your exterior mounted camera or put your AOA display there (hopefully someone a lot smarter than me will come up with a way to display indicated airspeed). OR, if you don?t like garbage cluttering up your clean windscreen, kindly disregard this post! ?I may do the same after I try it! Flight test to follow?

SOURCES:

LED?s ? www.superbrightleds.com

Mirrors ? www.firstsurfacedmirrors.com
www.highreflectivemirrors.com

Lens - www.surplusshed.com
http://rolynoptics.thomasnet.com
www.edmundoptics.com

Off the shelf ? Telrad telescope sight


hud3fc1.jpg


hud4aq7.jpg
 
I fly with a hud at work. It has several modes, multiple layers of information, duplicate information, and information that changes based on altitude. At best I consider it a major annoyance. At worst I think someday a NTSB report will read "A contributing cause of the mid-air collision was the pilots visual scan distracted by the HGS display".

That being said someone earlier mentioned a project using the back of the prop arc as a display for laser hud data. I think that is a great idea. If a glare shield mounted combiner was small enough and data displayed was limited I might see value in it.
 
Different Perspective

I flew with a HUD on the 737-800 for 5 years and thought it was the greatest invention since sliced bread. Situational awareness, eyes out of the cockpit and precision flying are 3 major contributions of a HUD. I would love to have one in my 8.

I hate to think anyone thinks of them as something that will contribute to an accident. Seems like maybe it's not being used correctly
 
RV8iator said:
I hate to think anyone thinks of them as something that will contribute to an accident. Seems like maybe it's not being used correctly
Click to expand...

I agree. I have found the best way to use it correctly is to place the combiner in the stowed position.
 
I fly a G-IV with HUD and EVS. The combiner is down for every takeoff, approach and landing - VFR or IFR. I agree with the analogy that HUD technology is the greatest thing since sliced bread, especially with the Enhanced Vision. I would like to think Dynon or some of the other low cost EFIS innovators are working on a practical HUD application for the experimental market. The EVS (infrared) will come later as the current cameras are the really expensive part of that equation.
 
Takes me back to the day when I built telescopes. Try giving Harden optical a ring maybe Larry would have some ideas. They're located in Bandon Oregon.
 
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