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Tip: Build AOA Lift Reserve Indicator Made Easy

B

Bill Phillips

Well Known Member
I mentioned a week ago that I built and installed an AOA LRI in the Bluebird and had several PM asking how for less than $100. Non electric and when fine tuned very accurate. Never worry about DA or stall speed again. So I'll write it out and I have five photos of what it looks like wing and panel.

Order online the gauge box as is shown. I think it cost $48. It is an auto type air pressure gauge. Comes with a bracket that works fine. Online find the free AOA LRI face page and print it out. Sheet shown in color photo. Unscrew the face bezel of the gauge and glue the cut out AOA you want onto the white face. Note the pin holes must line up to be accurate.

Order from Dynon their AOA probe. Can't remember what I paid, but was not much. Buy two brass fittings from the aviation section at Home Depot and sufficient tubing to get from the back of the panel to the first wing inspection panel hole on the left wing.

I cut a hole in the panel face. As an auto gauge it is not aviation standard. I think it was 2 5/8 inch. Connect tubes to the back of gauge and run them to the wing.

Remove the wing access panel, cut a hole and rivet two L brackets to sandwich the probe hub. Don't tighten too tight as probe is plastic. Mine was set at about 16 degrees to start with, but I adjusted it a bit as I fine tuned the stalls. Attach all and fly.

If your AOA does not show any movement reverse the tubing at the probe. (ask me how I know) Fly up and do power off stalls to see where the arm is at break. Land and adjust the angle of the probe. It took me seven flights to get it just right.

This is the second AOA I assembled for plane I built and believe they make me a safer flyer. There are five photos attached here if I did it right. If you want to call me at 478-731-9678

http://s1306.beta.photobucket.com/user/wphillips1/library/
 
Last edited:
Which model gage?

In looking up the Dwyer gages, there are many pressure ranges available. Which one is the correct gage?



Nice write-up! Thanks,
 
Last edited:
Bill Phillips said:
I mentioned a week ago that I built and installed an AOA LRI in the Bluebird and had several PM asking how for less than $100. Non electric and when fine tuned very accurate. Never worry about DA or stall speed again. So I'll write it out and I have five photos of what it looks like wing and panel.

Order online the gauge box as is shown. I think it cost $48. It is an auto type air pressure gauge. Comes with a bracket that works fine. Online find the free AOA LRI face page and print it out. Sheet shown in color photo. Unscrew the face bezel of the gauge and glue the cut out AOA you want onto the white face. Note the pin holes must line up to be accurate.

Order from Dynon their AOA probe. Can't remember what I paid, but was not much. Buy two brass fittings from the aviation section at Home Depot and sufficient tubing to get from the back of the panel to the first wing inspection panel hole on the left wing.

I cut a hole in the panel face. As an auto gauge it is not aviation standard. I think it was 2 5/8 inch. Connect tubes to the back of gauge and run them to the wing.

Remove the wing access panel, cut a hole and rivet two L brackets to sandwich the probe hub. Don't tighten too tight as probe is plastic. Mine was set at about 16 degrees to start with, but I adjusted it a bit as I fine tuned the stalls. Attach all and fly.

If your AOA does not show any movement reverse the tubing at the probe. (ask me how I know) Fly up and do power off stalls to see where the arm is at break. Land and adjust the angle of the probe. It took me seven flights to get it just right.

This is the second AOA I assembled for plane I built and believe they make me a safer flyer. There are five photos attached here if I did it right. If you want to call me at 478-731-9678

http://s1306.beta.photobucket.com/user/wphillips1/library/
Click to expand...

PCHunt said:
In looking up the Dwyer gages, there are many pressure ranges available. I am just guessing that the lowest range would be the one. Is this the correct gage?

Model 2-5000-0 Differential pressure gage, range 0-0.5" w.c.

Nice write-up! Thanks,
Click to expand...

The Dwyer gauge you want for an LRI clone is the 2-5002, 0-2.0" w.c.

The plastic probe is not a Dynon product, who sells it?
 
Looks like the aluminum LRI probe to me.
You can make your own with two pieces of al tubing J-B Welded together.
 
Bill Phillips said:
Remove the wing access panel, cut a hole and rivet two L brackets to sandwich the probe hub. Don't tighten too tight as probe is plastic.
This is the second AOA I assembled for plane I built and believe they make me a safer flyer. There are five photos attached here if I did it right. If you want to call me at 478-731-9678

http://s1306.beta.photobucket.com/user/wphillips1/library/
Click to expand...

Mel said:
Looks like the aluminum LRI probe to me.
You can make your own with two pieces of al tubing J-B Welded together.
Click to expand...

Mel, the probe is black nylon (note the original post above and the posted photos). I have one on my Legal Eagle that I procured from an individual but I don't know who manufactures them.
 
Maybe a silly question, but how did you run the tubing out to the wing?

I've got a Dynon pitot/AOA tube but haven't looked at installing it yet because I don't know how much work it would be to get the tubing run back to the cockpit... Do you need to remove a fuel tank? Or does it run behind the spar?

Actually, this might be a good place for a related question... Where can one cheaply find one of the mounts that the Dynon Pitot/AOA probe fits in? It's airfoil-shaped and may be called a Gretz mount, I think?
 
Outboard of tank andBehind the spar

In the 9 at least, you can easily reach in and touch each and every rib through the provided access panels. If you put snap bushings in the ribs you could easily thread through them in the blind. Even without the bushings I'm sure you could figure something out.

This dawned on me while skinning the bottoms, I wished I hadn't worried so much over making sure I had the right conduits and wiring runs in the wings.
 
Sam & Mel - You are correct

The Dwyer Meter is #2-5002 0-2.0. It's typed at the top on the photo of the paper with the dial faces. I'm pretty sure I got the probe from Dynon?, but I looked on their site and they sell something different. Maybe they changed models? I purchased and collected so many pieces and parts over the years as I was building for final assembly. I'm sure I bought it from a vendor on line. I'll check the papers at the hanger this weekend to see if I retained the receipt. The probe I installed on my first plane was an aluminum block, drilled and taped at the end for fittings made by a fellow builder and sold to me for $20. Mel is correct that it would not be much work to make one.
 
Dbro172 said:
In the 9 at least, you can easily reach in and touch each and every rib through the provided access panels. If you put snap bushings in the ribs you could easily thread through them in the blind. Even without the bushings I'm sure you could figure something out.
Click to expand...
The -9 must have more access panels... I think from the wingtip I could reach halfway to the aileron bellcrank, and from the bellcrank access panel I could reach the other half way and maybe an arm's worth towards the fuselage. But the inner wing would be off-limits.

I think my best option is to remove the wingtip and use a long straight stick to fish the AOA tube through the wing to the aileron bellcrank where the current pitot is. I could secure a tube near the probe and near the fuselage, but i'd have to let it "flop" in between. I've been wondering if running a conduit this way and securing it at each end would be adequate, maybe suspending the ends of the conduit in the center of the lightening holes, so it would "float" without hitting the holes in the intermediate ribs. Knowing my luck it would resonate and beat up the inside of my wing. :)
 
I have a related question:
Advanced Flight Systems has an angle of attack indicator, you know, the one with the cool LED display.
Although they use a computer with "proprietary algorithms", I suppose a pilot could interpret the info on a gauge.
Anyway, the point I want to make, is that they don't use a Pitot mast, instead, they have a flush port on the top & bottom of the wing.
No Drag. Just pressure differential.
DO you think this could be adapted to the Dwyer 2-5002 0-2.0 gauge?
 
Maybe

SHIPCHIEF said:
I have a related question:
Advanced Flight Systems has an angle of attack indicator, you know, the one with the cool LED display.
Although they use a computer with "proprietary algorithms", I suppose a pilot could interpret the info on a gauge.
Anyway, the point I want to make, is that they don't use a Pitot mast, instead, they have a flush port on the top & bottom of the wing.
No Drag. Just pressure differential.
DO you think this could be adapted to the Dwyer 2-5002 0-2.0 gauge?
Click to expand...

Possibly. Look at an Advanced port setup. You can probably duplicate it. Will it work??? One way to tell.

The Advanced system algorithm changes when you lower the flaps.

I sure do love mine. Only problem is the cost$$$$$:eek:
 
Snowflake said:
Maybe a silly question, but how did you run the tubing out to the wing?

I've got a Dynon pitot/AOA tube but haven't looked at installing it yet because I don't know how much work it would be to get the tubing run back to the cockpit... Do you need to remove a fuel tank? Or does it run behind the spar?

Actually, this might be a good place for a related question... Where can one cheaply find one of the mounts that the Dynon Pitot/AOA probe fits in? It's airfoil-shaped and may be called a Gretz mount, I think?
Click to expand...

Rob, running the tubing in a completed RV-6 is a little more challenging than the later models but it can definitely be done. There is only one inspection plate in the RV-6 wing but you can gain access to all the lightening holes behind the spar if you remove a wingtip. A fishing pole can be used to feed the tubing through the wing.

http://thervjournal.com/liftreserve.htm

I ran the LRI tubing through the conduit I already had in place but if that hadn't worked I would have used the lightening holes securing it at the inspection hole and the root of the wing. It will ride just fine in the lightening holes.

The tubing comes into the fuse behind the spar and I found a space between the top spar cap and the seat base where the tubing could pass over the top of the spar. It then goes up the side of the cabin to behind the panel. I intended to clean up that part of the installation but have decided it looks fine as is.
 
just another crazy idear!

Snowflake said:
Excellent! And half the price of the one I found at Aircraft $pruce not five minutes after I first asked... :p
Click to expand...

So Rob, looks like you are going with the mast, and ports facing forward and down to give you the pressure differential.
After reading a long thread on the RV-12 guys making a $10 AoA system to feed air to their Skyview systems, I wondered if there was another angle here.:rolleyes:

What if you drilled the top & bottom of the wing like the fancy systems, ( maybe harder for you & me to do) and then connected the plumbing to either a gauge in the panel, or just a 'sight-glass' affair....... like the fool-proof fuel tank level indicators of old?
My physics and math may be off, ( ok, almost surely) but if there is a max of 2" (of water column) pressure differential between the top and bottom of the wing at max AoA, would this not show as 2" of movement in the fluid level a piece of clear tubing stuck on my panel?

tell me I'm crazy, but don't make fun of my $3 AoA system..... just yet!
 
Running AOA tubes

On my 6A, (didn't build it) after much trial and error I've found that one can run the two nylon tube to the wing inspection panel. I did not like the idea of the tubes lying on the lightning holes. The tubes run behind the wing tank and in front of the spar. There is a small channel there. They then can be accessed in the wing root.
Hope this helps,
Tony
 
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