David_Nelson

David_Nelson

Well Known Member
I've been doing some research on what and how folks are installing backup altimeter and airspeed indicators. What I haven't seen yet is why folks aren't considering some of MGL's smart/maxi/infinity singles solutions. For the price, they seem to offer good bang for the buck.

Take, for example, the ASX-1 airspeed and altimeter combo. The Smart (2.25") can be had for 285 USD and Maxi (3.5") single can be had for around 300 USD. That's a little more $$$ than a single UMA altimeter from Van's (223 USD) and 40% cheaper than the cost of implementing both alt (223 USD) and asi (256 USD) from Vans.

Thanks,
 
The main reason these aren't normally considered for back-ups is that they require power.
Normally back-up instruments should be independent of aircraft systems. They should not require electrical or pumps.
 
I have been waiting for more info on the Infinity singles because they look nicer and have a knob. Any word MGL? Any pricing yet?
 
Mel said:
The main reason these aren't normally considered for back-ups is that they require power.
Normally back-up instruments should be independent of aircraft systems. They should not require electrical or pumps.
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Hi Mel,

That's what I initially thought. However, given the increasing complexity and electrical dependence of our planes, I came to the conclusion that it'd be better to improve the electrical system and take advantage of these types of goodies.

Now, I'm a low time VFR pilot and may not be seeing the "big picture". If this is a bad idea, why?

Thanks,
 
On the other hand, if you're setting up a glass panel where your EFIS and GPS (assuming you have a Garmin x96, AvMap, Lowrance, etc) have internal batteries, how important is electrical independence for your backups?

If the ship's power fails, the EFIS will still run. If the EFIS fails due to internal fault, the backup will still have power.

It's only in the event of concurrent failure of both the EFIS internals AND the ship's power that you are left with no operational indicators. Could it happen? Sure. But this danger exists in any setup, regardless of power source. Any time you have a fallible system with a fallible backup, the possibility of coincidental failure exists.
 
The current draw on the MGL instruments is so low that you could use a 9volt transitor radio battery and have 1-2 hours of operation.

Rv9Ralph
Livemore, CA
 
David_Nelson said:
... given the increasing complexity and electrical dependence of our planes, I came to the conclusion that it'd be better to improve the electrical system and take advantage of these types of goodies.
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David,
That's why it is important to not tie into the electrical system(s) for your backup instruments. It is very possible to have an issue that takes everything down at the same time. Steam gauges are reliable, light, and don't take power. (I'm talking about AS, Alt, VSI, and slip ball.)

Also, connecting them to your other instruments only takes a simple "T" fitting.
 
Brantel said:
I have been waiting for more info on the Infinity singles because they look nicer and have a knob. Any word MGL? Any pricing yet?
Click to expand...

Pricing has been released to the distributors some time ago and we are shipping these things as fast as we can make them. The new Infinity range will replace the older Smart Single range. They are marginally higher in price compared to the Smart Singles (some have remained at the old prices, some have increased a small amount).
All of them have a rotary control with "click" button function, screen viewability is much improved and current consumption is around half of what it used to be (which means it's now really low). Also all software running on these things has been rewritten from the ground up and some of the instruments have been combined - for example the previous EMS-503 and EMS-582 engine monitors have now been combined into a E3 universal engine monitor and the fuel flow computers FF-1, FF-2 and FF-4 have been combined into the new FF-1. The FF-4 BTW is a nifty fuel flow unit that does not need a flow sender if you have an electronic ignition system - it monitors one of your injectors to derive fuel flow.

We planned this range for a long time but had to save up a bit to be able to afford the tooling for the new, very nice housing which is very expensive.

Rainier
CEO MGL Avionics
 
Power consumption of Electronic Backups...

Hi guys,

RV9Ralph said:
The current draw on the MGL instruments is so low that you could use a 9volt transitor radio battery and have 1-2 hours of operation.
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Very good idea... And to fill in the numbers:

Example Infinity with no sensors connected:
------------------------------------------
Infinity AV1: 9 mA at 12V (Backlight OFF) ... or ...
Infinity AV1: 10 mA at 9V (Backlight OFF) ... or ...
Infinity AV1: 39 mA at 12V (Backlight ON) ... or ...
Infinity AV1: 50 mA at 9V (Backlight ON)

see http://www.mglavionics.co.za/Infinitec/Infinity.html

AHRS sensors:
--------------
SP4: 48 mA at 9/12V (Heating elements OFF) ... or ...
SP4: 68 mA at 9V (Heating elements ON) ... or ...
SP4: 76 mA at 12V (Heating elements ON)
SP2: 35 mA at 9/12V

http://www.mglavionics.co.za/sensors.html

Maxi Singles:
-------------
AV-2: 38 mA @ 9V/12V (Backlight ON)
AV-2: 17 mA @ 9V/12V (Backlight OFF)

http://www.mglavionics.co.za/maxi.html

Primary flight panels:
--------------------
Flight II: 77 mA @ 9V/12V (Backlight ON)
Flight II: 56 mA @ 9V/12V (Backlight OFF)

http://www.mglavionics.co.za/flight2.html

Now you just need to find your battery's capacity, and we can work out how many hours your backup will last.

And remember: 99% of the products now have silver buttons! :D

Regards
 
I wonder if a 9V is the best option. At 100mA draw (120mA worst case) you wouldn't get much operation before the voltage drops below 8V (min V from AV-1 spec sheet.) I realize it may operate below 8V, but how much lower?

The 9V show 400mAh capacity @100mA draw, but that is all the way down to 4.8V.

Maybe a better (but more pricey) option would be 4 lithium primary cells.

Edit: 120mA assuming AV-1 & SP-4 worst case. Also, if this is used as a isolated backup with a switch to power it up if needed, how long after power-up (in flight, no guarantee of straight and level) before it gives good attitude guidance?
 
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For the SP-4 with AV-1 I would not go for a 9V battery, while it is possible to run at just below 8 volt the SP-4 is going to start toppling at much below that.
I think the comments on the 9V battery where more related to the airspeed/altimeter combo ASX-1 which of course has a much lower current draw.
Personnally I'd perhaps go for one of those tiny sealed lead acid batteries (perhaps the 1Ah variety) and connect it to the aircrafts power rail through a diode and then a switch to the backup instruments. This way you would have sufficient capacity even though the battery will not charge to 100% level due to the small voltage drop on the diode.

Rainier
CEO MGL Avionics

amilder said:
I wonder if a 9V is the best option. At 100mA draw (120mA worst case) you wouldn't get much operation before the voltage drops below 8V (min V from AV-1 spec sheet.) I realize it may operate below 8V, but how much lower?

The 9V show 400mAh capacity @100mA draw, but that is all the way down to 4.8V.

Maybe a better (but more pricey) option would be 4 lithium primary cells.

Edit: 120mA assuming AV-1 & SP-4 worst case. Also, if this is used as a isolated backup with a switch to power it up if needed, how long after power-up (in flight, no guarantee of straight and level) before it gives good attitude guidance?
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How low can you go?? (some numbers)

Hi Andrew,

amilder said:
I wonder if a 9V is the best option. At 100mA draw (120mA worst case) you wouldn't get much operation before the voltage drops below 8V (min V from AV-1 spec sheet.) I realize it may operate below 8V, but how much lower?
Click to expand...

At 5.2 V the AV-1 still looks fine here on the bench. At 4.9V it starts taking strain... and at 4.7V is would say it is just about useless. At 4.2V it is gone. I would expect similar results for the other Infinity instruments (for altitude and airspeed backup).

The SP-4 needs more than 6.7V. The processor will run at less, but the sensors need a regulated 5V, which goes missing below 6.7V.

amilder said:
Also, if this is used as a isolated backup with a switch to power it up if needed, how long after power-up (in flight, no guarantee of straight and level) before it gives good attitude guidance?
Click to expand...
The SP-4 was designed and tested to be started in "near non accelerating flight" - does not need to be straight-and-level flight. (Example: constant climb rate would be non accelerating / perfect too - irrespective of attitude.)

Low pitch rate or shallow bank would give you something very close to the truth. Without an exact spec on the conditions, it is impossible to give an exact answer on the performance.

The SP-4 - AV-1 combo takes 11 seconds from power on till the displayed attitude is valid.

Regards,
 
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How does one do that?

David_Nelson said:
Hi Mel,

That's what I initially thought. However, given the increasing complexity and electrical dependence of our planes, I came to the conclusion that it'd be better to improve the electrical system and take advantage of these types of goodies.

Thanks,
Click to expand...

This is a good point...one that this electrical engineer does not know how to address. For example, how do you improve the electrical system to the point that a lightning strike does not kill every last bit of silicon on the airplane?

I don't have an answer. But I do know that vacuum gyros and pneumatic airspeed and altitude insruments will keep working when everything electronic has died.

Or do we just write this off as an unreasonable failure mode because "we don't fly near thunderstorms?"
 
mgomez said:
For example, how do you improve the electrical system to the point that a lightning strike does not kill every last bit of silicon on the airplane?
Click to expand...

I guess that is what I was thinking of too- The device is powered off and not connected to the airframe or the power supply at all- flick a switch to turn it on in the event of catastrophic electrical failure.
 
mgomez said:
Or do we just write this off as an unreasonable failure mode because "we don't fly near thunderstorms?"
Click to expand...


Personally, that is pretty much what I do - but I have some good rationale behind it (at least it is good for me - YMMV). I like to look at what is actually causing accidents - fatal and otherwise - out there in the real world. you see lots and lots of landing accidents, a few engine failures, and then those pesky "continued VFR into IFR conditions" followed by loss of control. I can't remember seeing a "total loss of flight instruments due to a lightning strike" in the recent past. Certainly it CAN happen - I won't argue with that. But probability wise, you are much more likely to screw up a landing or buy it due to a poor decision than from having your entire electrical system blown out in flight.

Is it gambling when the odds are so far in your favor as to be inconsequential? Possibly - but I acknowledge that while you can manage risk sensibly, you can never completely eliminate it.

Just my thoughts,

Paul
 
You're probably right- at first look, it seems like a distinct single-point failure, but once you look at the electrical system design, battery backups, surge protection, etc, it becomes less of a worry. I'm just now starting to think about electrical system design, and I'm still waffling on this issue...

Rainier and Nicol, thanks for answering my questions:D

Ironflight said:
Personally, that is pretty much what I do - but I have some good rationale behind it (at least it is good for me - YMMV). I like to look at what is actually causing accidents - fatal and otherwise - out there in the real world. you see lots and lots of landing accidents, a few engine failures, and then those pesky "continued VFR into IFR conditions" followed by loss of control. I can't remember seeing a "total loss of flight instruments due to a lightning strike" in the recent past. Certainly it CAN happen - I won't argue with that. But probability wise, you are much more likely to screw up a landing or buy it due to a poor decision than from having your entire electrical system blown out in flight.

Is it gambling when the odds are so far in your favor as to be inconsequential? Possibly - but I acknowledge that while you can manage risk sensibly, you can never completely eliminate it.

Just my thoughts,

Paul
Click to expand...
 
On the spot

OK Rainier, how long before we see an overhaul of the Maxi series? I like the instruments but I am struggling with the ASI/ALT indicator. I think that the ASI should be on the top as it is the most critical in my mind.

I would also be interested in a horizon that will not need an additional 1K part to function. Are you entertaining making a horizon with a built in AHRS that will be under a thousand clams?

I think it would be a big hit if your instruments had color screens as well. I am not sure but I think that I talked to someone about six months ago and thought that they told me that the faces of the Maxi Series were going to be overhauled as well. Is this correct?

Thanks for great products.
 
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ww2planes said:
OK Rainier, how long before we see an overhaul of the Maxi series? I like the instruments but I am struggling with the ASI/ALT indicator. I think that the ASI should be on the top as it is the most critical in my mind.
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They will change as well but it is still some time off. We are busy with tooling for a new 3.5" range now and are busy getting our own automated SMD production line. No more fighting with contract manufacturers - Hurray !!!

I would also be interested in a horizon that will not need an additional 1K part to function. Are you entertaining making a horizon with a built in AHRS that will be under a thousand clams?
Click to expand...

Shall we say something like a D...N D-.0 at half price ?
Who knows ? Perhaps we are working on something like that......

I think it would be a big hit if your instruments had color screens as well. I am not sure but I think that I talked to someone about six months ago and thought that they told me that the faces of the Maxi Series were going to be overhauled as well. Is this correct?
Click to expand...

I agree - but only under the condition that the screens are 100% sunlight readable. Small color screens up to now just don't cut it. Yes, there are transflective screens - but none has so far impressed me.
The small monochrome screens are still miles ahead when it comes to sunlight readability.

Thanks for great products.
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My pleasure. Keeps me from getting bored...

Rainier
 
Thank you.

All good news. I can't wait to see what is next. Your products are very impressive and I intend on having some version of your future in my panel.

Just hurry, I am impatient. LOL.
 
MGL AV-1

I'm considering a new attitude / DG to replace my defective ADI. Can someone give me some insight on the AV-2 MGL attitude indicator.
 
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Just curious of anyone has gone to the steps of adding a rechargable battery to the ASX-1 that is trickle charged by the aircraft's main bus?

If anyone has, would you be willing to spell out what you did for a non-electrical type? :)

I can read schematics, most of the time, but sitting down and figuring out what resistor/diode/thingamajig I need to get the job done is not my forte. :)

Thanks

Jeff
 
Back up system

N941WR said:
David,
That's why it is important to not tie into the electrical system(s) for your backup instruments. It is very possible to have an issue that takes everything down at the same time. Steam gauges are reliable, light, and don't take power. (I'm talking about AS, Alt, VSI, and slip ball.)

Also, connecting them to your other instruments only takes a simple "T" fitting.
Click to expand...

I agree with Bill's point above.

Some critical points to consider designing a back-up system are as follows:
-Designing a system that operates when the power or vacuum pump fails.
-Consider back-up choices that do not rely on the same source of power.
-Electric back up system: provide independent battery pwr & wiring.

Portable GPS is used as a back-up system by many with it's own power.
 
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