# HUD

### Help Support Homebuilt Aircraft & Kit Plane Forum:

#### Bigshu

##### Well-Known Member
So (5) rudimentary map, for gods sake you only need to know where you are in relation to a few things and combine that with your heading information, you do not need to know how to get to Mars.
I kind of like the synthetic vision that puts pointers with airport IDs, in your field of view. Just steer toward the one you want to land at. No heading bugs, no magenta line, just point and fly (obstacle avoidance is on you).

#### Bigshu

##### Well-Known Member
Did anyone look at the XHud1000 that was on display at Oshkosh? It was set up in a Cessna, and was very impressive. Put a target on the windscreen that looked like infinity, with AOA and ribbon strips for altitude and airspeed. Kind of a clunky install, but on a homebuilt it could be incorporated during the build instead of glommed on after the fact. Seems like it isn't crazy expensive either:
DUALAV XHUD1000 HEAD UP DISPLAY | Aircraft Spruce

#### rv7charlie

##### Well-Known Member
If that Hudly gadget could receive something like AvAre or Foreflight, now THAT would be something worth having. HUD AoA, speed, an ILS right in the pilot's line of sight but not blocking the view out the windshield... that would be PFC in my book.
Here you go...

#### User27

I have a little experience working with HUDs - the big deal is the ability to look through the HUD and have everything in focus. The information in the HUD is in focus when the pilot is looking into the distance (collimated at infinity is the tech term). If your HUD does not do that is there much benefit from a regular display? They can be particularly useful when trying to bomb something, shoot at something or land somewhere - the target can be displayed in the HUD, the pilots "just" points the aircraft at it. The most significant draw back is the limited field of view of the HUD, that means the pilot's head must be precisely in the correct position to view all the data. One problem is accurately painting the data in the display. The biggest benefit is when the the HUD is on the pilot's visor as the field of view problem disappears, but now the direction in which the pilot is looking must be measured. When there problems can be solved for < 10K it will be a useful technology for GA. Sticking a see-though display panel on the glareshield and calling it a HUD is fairly gross mis-selling! #### Heliano ##### Well-Known Member User27, you are absolutely right and that is the reason a honest HUD (or HGS, as Rockwell Collins calls it) is VERY expensive: the image generated is not optically at the combiner. The symbols are optically a holography ahead of the aircraft, so that the pilot does not need to adapt the eye focus when he switches from the symbology to the outside landscape. And that is why it is the only way an aircraft can be certified for hand-flying a CAT IIIa approach. And that is why such a HUD can show a touchdown point on the runway and - believe me - you move your head from side to side but the touch down symbol remains on the runway. Instead of a simple, non-holographic HUD, perhaps a big PFD with synthetic vision can provide more situational awareness. However I have to confess I have NO experience with non-holographic HUDs. #### bifft ##### Well-Known Member Log Member hat is the reason a honest HUD (or HGS, as Rockwell Collins calls it) is VERY expensive It doesn't necessarily need to be all that expensive. These have the image focused at infinity, and don't cost all that much: Company Seven | Telrad, Inc. Telrad Sight for Telescopes. Bulky and just a fixed reticle instead of a changing screen, but somebody who knows optics could probably build something similar around a screen instead of a LED with a mask. Or maybe have the mask be active? #### Bigshu ##### Well-Known Member Isn't this along the same lines as holographic sights in shooting? A red dot sight puts the dot on the point of impact, and even slight alignment changes don't change the view of the dot, which still shows point of impact. Adding more data to an aiming point could be something to shoot for (Ha!) in an aviation HUD. If I can get lines for attitude, a heading bug, and a landing point projected on a device that looks collimated to infinity like a red dot, that would work well even if you don't have speed and altitude tapes on the side. #### Daleandee ##### Well-Known Member I was taught that H.U.D. was when you picked your head up and used your eyes to look out the windscreen at the world that is displayed right in front of you. Every few seconds a scan of the panel instruments confirms what you see outside and that the temps and pressures are all good. Giving pilots more between their eyes and the objects outside seems not to be a great idea to me. I know it works for our military and some others but most of us here are flying simple day, VFR, machines. Some have disagreed over using a radio, ADSB, or the effectiveness of "see and avoid." If they struggle with those simple things do we really need another distraction? #### Bigshu ##### Well-Known Member I know it works for our military and some others but most of us here are flying simple day, VFR, machines. That's a fair point, and I agree for the most part. I do think an aim point on a runway that changed color depending on whether or not you're on glideslope would be a nice upgrade over a VASI or PAPI. Or one that showed an appropriate touchdown point when wake turbulence is a concern. #### BJC ##### Well-Known Member That's a fair point, and I agree for the most part. I do think an aim point on a runway that changed color depending on whether or not you're on glideslope would be a nice upgrade over a VASI or PAPI. Or one that showed an appropriate touchdown point when wake turbulence is a concern. My EFIS has a flight path vector indication. That will show the impact point on the runway when in a steady approach, assuming no flair. I’ve never looked at it on final, but find it useful for other purposes. BJC #### dtnelson ##### Well-Known Member I apologize if this is a dumb question; it probably is; but I've often wondered if using something like this used to project a display from my (Garmin) glass panel onto a semi-transparent glass, mounted at an angle, would work? (Blatently trying to take advantage of the expertise on this forum) Dave #### rv7charlie ##### Well-Known Member Define 'work'. ;-) If you could get Garmin to flip the output image, and you mounted the Garmin face up under the glass, you'd get the image on the glass. but how visible it would be under various conditions would be highly variable, there'd actually be more info there than you want (sometimes blocking your view outside, and as others have said, the focus is wrong, requiring your eyes to refocus inside the cockpit to read it. If you're talking about a separate device to display the info, that's what GRT has done with the Hudly (post #23). It's not perfect; it doesn't focus at infinity like the megabuck military stuff, but it apparently does 'work'. I'd think that the biggest advantage could be during an IFR approach, because it would minimize required head movement, which reduces vertigo risk. #### Heliano ##### Well-Known Member In my humble opinion, based on my experience, the depiction of touchdown point is useful in two cases only: a) in a holographic HUD (similar to the holographic sights in shooting as described by Bigshu, except that a HUD has more complex and more dynamic symbology); and b) on a PFD, associated with synthetic vision (3D terrain, etc.). BJC brings up an important point: flight path vector - the most common symbology used in HUDs. FPV is more intuitive, allows more precise flight and conveys more information than a standard flight director. I believe that FPV will be mainstream in the future not only in transport aircraft but in general aviation aircraft as well. #### Bigshu ##### Well-Known Member I apologize if this is a dumb question; it probably is; but I've often wondered if using something like this used to project a display from my (Garmin) glass panel onto a semi-transparent glass, mounted at an angle, would work? (Blatently trying to take advantage of the expertise on this forum) Dave Garmin used to have an automobile GPS that sat on the dash and projected speed and NAV info. They don't support the device anymore, and I've found no way to use a 3rd party app with the hardware (yeah, it's Garmin), nor have the knowledge of how to hack it to unlock the hardware. It's a paperweight now, but I think it had potential if you wanted some basic info, not the whole 9 yards in your windshield. I think having airspeed, vertical speed, heading bug, and a touchdown pip would be handy. Moving map, engine info, etc., maybe a little too much info. #### 12notes ##### Well-Known Member Log Member The further away the projection gets from your eye, the more difficult keeping an infinity-focused HUD correctly in view gets. Probably the easiest solutions would be based on one of the augmented reality glasses. (Augmented reality differs from virtual reality in that virtual reality is a replacement for natural vision, where as augmented reality is overlaid on your natural vision.) Head tracking and the associated display adjustment is a lot simpler problem than making a wide field of view HUD, and has the benefit of working even when looking to the sides. #### User27 ##### Well-Known Member If "work" means can a transparent display be generated on a "glass" pain on the glareshield - the answer is yes. I don't have any details but GRT has done it - see earlier posts. Will it make a difference to how you fly your aeroplane? I doubt it. If you invest\$ in the system will you admit to your self it didn't make much difference? Most owners wouldn't!!
My preference is to mount the display that is used most often at the top of the panel, as close to the eye line when looking out the window as possible. Particularly so the display showing airspeed (ASI or EFIS showing speed) is as close as possible to the direction I will be looking when landing. I have recently been doing some formation flying - I would really like a slip ball and tacho at the top of the panel, difficult to pick up the information when grabbing a quick look inside. Not sure a HUD would help - a visor display would be really useful!!

Last edited:

#### cluttonfred

##### Well-Known Member
I remember seeing a simple HUD for skiers and cyclists that projected the basic info only (speed, course, etc.) on a helmet visor. Something like that, say ASI/ALT/VSI plus compass heading, skid ball, and radio frequencies, could be very handy.

#### User27

##### Well-Known Member
Yes! Flight path vector is also really useful - when coming into land park the FPV on the end of the runway!