Touch Screen Avionics

[Stuart]

I found a new company that has very thin, touch screen instruments for the homebuilt market, the prices seem very reasonable too.

 

Aveoengineering.com

 

I am not sure if they are out yet or not, but all the instrumments talk to each other, seems like a sweet system

[H.Zwakenberg]

There's that Silicon Valley company with a fruit in its name.... One of their latest offering obviously lets you run software that you can take with you in the blue wide yonder, check it out....

 

http://blog.experimentals.de/aviation/primary-flight-display-pfd-on-your-apple-iphone

 

Obviously just a backup instrument, but still, I like the idea....

 

cheers

Hans

[Marc Zeitlin]

Obviously just a backup instrument, but still, I like the idea....

Not again with this.

 

The Apple iphone does not have any gyros in it. It only has accelerometers. This means that it can't do anything that a bubble level can't do. It does NOT know which was is up - it only knows which way the acceleration vector is pointing.

 

Using this software, which mimics the LOOK of an EFIS, but can't actually tell your orientation, is a guarantee of death in instrument conditions, and will do absolutely nothing in VFR conditions other than keep the screen level if you're in a coordinated turn and wiggle a lot in turbulence.

 

Please don't propagate the notion that this is anything other than a toy.

 

From the software writer's website:

 

"Important note: A limitation of this basic version of iHUD is that the horizon depends on the on-board accelerometers only. This means that the horizon does not display the earth horizon as a reference of a vehicle in an accelerated attitude. It will display the acceleration of the vehicle only...."

 

and:

 

"*) The iPod touch has no on-board GPS receiver..."

 

So your claim that the unit uses GPS to help out the "inertial sensors" is incorrect.

[H.Zwakenberg]

ah, thank you for pointing this out Marc.

I've seen other devices that rely on GPS data to be able to somehow derive a horizon-like device at all, now I understand why this is the case.

Thanks again!

[Marc Zeitlin]

I've seen other devices that rely on GPS data to be able to somehow derive a horizon-like device at all, now I understand why this is the case.

If the GPS position info is obtained fast enough in relation to the speed of the aircraft, one can deduce a flight path (horizontal and vertical). Then, if you assume something close to coordinated flight, one can calculate what the pitch and roll angles must be close to in order to achieve that flight path. It's somewhat roundabout, but can work somewhat. Normal once/second updates are not fast enough. Even 5 Hz GPS updates are probably inadequate in rapidly changing attitudes.

 

Now, one thing that folks have been working on is multiple differential GPS sensors on one aircraft - one on the nose, one on the tail, and one on each wingtip. With this, one can easily deduce the attitude of the aircraft directly by knowing the actual vertical position (within a few cm) of each point on the plane. Since DGPS is not widely available, and the sensors are very expensive, this is purely an academic exercise at this point (or at least as of a few years ago, the last time I read anything about it).

 

With this setup, you don't need ANY other flight instruments - you get altitude, VSI, GS, AI, and heading.

 

Personally, while I'm happy to rely on an external information source for navigation info, there's no way in hell that I'd rely on one for primary flight instrumentation. That had better be an on-board gyro (preferably electronic without the need for GPS stabilization - magnetometers are OK, since the earth's magnetic field rarely takes a vacation).

[emteeoh]

 

Now, one thing that folks have been working on is multiple differential GPS sensors on one aircraft - one on the nose, one on the tail, and one on each wingtip. With this, one can easily deduce the attitude of the aircraft directly by knowing the actual vertical position (within a few cm) of each point on the plane. Since DGPS is not widely available, and the sensors are very expensive, this is purely an academic exercise at this point (or at least as of a few years ago, the last time I read anything about it).

 

I have no first-hand experience with them, but judging by what I've read in some of the rocket builder blogs (armadillo and unreasonable rocket), the DGPS'es are not terribly reliable, and VERY noise and vibration sensitive. AFAIR, both ultimately scrapped them in favour of gyros.

[H.Zwakenberg]

@ Marc:

 

what you described is likely exactly what Moving Terrain did to create their new GPS-based backup EFIS:

http://www.moving-terrain.de/lang-en/produkte/module/mt-efis-kuenstlicher-horizont.html

Their statement that this device is not suitable for helicopters confirms that they need forward velocity to compute the derived values.

 

 

@ EmTeOh:

You're right about even DGPS signals having quite a bit of jitter in the signal, but modern adaptive digital filtering techniques can remove most if not almost all of that. I've done development work in exactly this area: removing noise from time series signals.

 

cheers

Hans