Lift Reserve Indicator (LRI)

Hello all,

I'm mid-fuselage and pretty much planning all the plumbing and wiring for my RV-7. I'm building my own Lift Reserve Indicator (LRI) per:
http://www.ch601.org/resources/aoa/aoa.htm

I've read what I could find here and elsewhere (including InAir's site, LRI Site, and Sam Buchanan's GREAT page but wondered if anyone that has one (especially you Sam) that they've bought or built could help with these questions:

1. The plans call for 3/16" ID tubing. I just bought 20' of that in vinyl at my local Ace Aviation Supply and it is pretty big stuff. I'm wondering if I could scale it down to 3/16" OD poly or even smaller for the majority of the run.

2. I bought brass barbed fittings for the 3/16" tube to 1/8" NPT and also for the 3/16" tube to tube for the wing root connect. Any objections to brass vs. nylon other than the small weight penalty?

3. I'm planning on heat shrinking over any of the barbed connections and wonder if a bit of RTV between the junction and the heat shrink would be wise?

4. I'm going to order the Dwyer 2-5002 (0-2" H20) indicator and panel mount it toward the top of the panel. Anyone have any thoughts/regrets regarding it's location or configuration?

5. I'm planning on putting the LRI probe in the inboard inspection panel of the right wing along with an OAT sensor. The alternative is in that bay but NOT on the panel itself. Thoughts?

6. Finally, for those that have rolled their own, any thoughts/tips/gotchas on machining the probe itself? I'm planning to enlist the aid of a cousin with a mill.

Thanks in advance,

George

1. The plans call for 3/16" ID tubing. I just bought 20' of that in vinyl at my local Ace Aviation Supply and it is pretty big stuff. I'm wondering if I could scale it down to 3/16" OD poly or even smaller for the majority of the run.

2. I bought brass barbed fittings for the 3/16" tube to 1/8" NPT and also for the 3/16" tube to tube for the wing root connect. Any objections to brass vs. nylon other than the small weight penalty?

3. I'm planning on heat shrinking over any of the barbed connections and wonder if a bit of RTV between the junction and the heat shrink would be wise?

Click to expand...

George, thanks for the kind comment!

You might make a trip down to the aviation department of Lowes or Home Depot and look at the pitot/static tubing and fittings they keep in the appliance area. They call it "ice maker tubing and fittings" but it is about the slickest setup I have seen for quickly and inexpensively plumbing a pitot system. The fittings are available in the usual variety of NPT sizes and also have els and tees. The tubing just pops into the fittings and they are tight. By the way, these fittings work great with the nylon tubing shipped in Vans' kits.

Good luck with your LRI! I think you will enjoy flying with it.