Univair Sight Gauge Balls... are these flight critical?? :-/

[James]

Hi Everyone,

I'm up to making my sight gauges, I'm going with Battson's concept of the PVC tube between two elbows.

So, I got online today and track down the little sight balls, Univair Part number U10853-000, $6 USD each.

Battson said to order three, in case you lose one down the back of the sofa or something.
I said, righto I'll order four, and then I can give my two spares to the next BH builder who needs them down under.

"Thanks for your order, that will be $55 shipping."

So my question is:

1) Do you even need these balls? You can see the blue colour of 110LL pretty well against a white background. Has anyone just left them out?

2) Does univair sell anything else people commonly want on their projects? It seems like I can order anything I like, it's always $55.

3) Does anyone want to set up their own international freight business in direct competition to Univair? That's a fair old margin you can undercut them there, and still make a profit!



Thanks for the tips guys,

James



PS - I got one over on Dynon Avionics yesterday. I bought the pneumatic tubing kit for their pitot probe last month, and discovered that one of those tiny 1/8th flare sleeves included in the kit was defective from manufacture, so I asked for a replacement. They happily sent me another one at no extra charge - it arrived yesterday in a cardboard box 14" x 10" x 10". Plus bubble wrap. I proudly opened the box in front of everyone at the post office, and extracted the sleeve. Now that's shipping!!!

[jaredyates]

Need any Bearhawk hats? I might be able to help.

[whee]

My opinion, the balls aren’t necessary but they are nice to have.

Mine worked for a while then became stuck at the top of the site gauge. It wasn’t an issue to still see the fuel level. I’ve been running mogas for the past 40 hours and have found that it has clouded and hardened the PVC tube I used. I’m switching to some other fuel line but there isn’t a size available that fits the balls.

[zkelley2]

You can see fuel(or any liquid) in clear line fine. They're nice I guess, but completely unnecessary. I've got 2 I could send as I won't be using them.

[tailwind]

My sight gage balls become stuck and the tube does harden. I replace my tubing every other year. Having a spare ball would be nice. I have dropped the ball during tube replacement several times and spent several minutes looking for them. They bounce and travel a great distance on cement floor. It is best to recover the ball but sometime I may not find it. Some horizontal lines behind the sight tube does make it easier to see the fuel level.

[James]

Great, thanks for the info guys - especially the confirmation zkelley that you can see the level fine without the balls.
I'll leave them out. Cuts down on my weight :-)

So Tailwind, the horizontal lines make it easier to see the fuel level, but I was wondering if some vertical or diagonal lines that get broken by refraction might aid as well. Something to experiment with down the track.

Thanks again for the help, much appreciated.

James

[zkelley2]

My old airplane's "fuel sight gauges" was the tank was fiberglass and you could see the inboard tank walls from the cockpit. Enough light got through the fiberglass to see the fuel level.

The balls are almost an oddity compared to the plain sight gauges out there.

[Rollie]

I first made my sight gauges just like the ones on line, with the cut away aluminum tubing housing the clear lines. The metal tubing is supposed to act as a clamp over the elbow fittings but after about 15-20 hours of flying one of them started leaking (probably from me always trying to squeeze the plastic tube to free the orange balls which would get stuck in the tubing. ) I ended up replacing the plastic tubing and leaving the metal off altogether. No metal tubing, no lines or markings and I can see the fuel level just fine. I think that several years down the line when the clear tubing gets less clear the orange balls might be helpful and they are a nice idea but for tubing that comes from the supplier rolled up, when you straighten it out it is always sort of flattened out, not round and the balls tend to get stuck somewhere and don't freely float on top of the gas.

Short version, if I were to make them again, I would skip the orange balls and the metal housing, just go with the clear tubing attached to the elbows with hose clamps. My interior is a light gray color and the fuel shows up well against that, maybe other interior colors would need the white/black hash marks behind the sight gauge.

[svyolo]

I still have the Superthane hose that I was going to make sight gauges out of. I have seen how Carbon Cubs do it, but don't like it. The Superthane is good at keeping its shape around corners. A little heat and I could put a fairly tight radius on it. It would be like CC does it, but not stick out so much. I think it would be very simple, and look pretty good.

[robcaldwell]

As I researched ideas for sight gauges, I decided to buy preassembled. Here are some of the choices I found. I went with Cub Crafters.

Cub Crafters - Pricey, but well made: http://store.cubcrafters.com/Fuel-Si...el_p_1213.html

Low Brow Customs - Designed for motorcycles, can be used in other applications: Lhttps://www.lowbrowcustoms.com/diy-...iABEgK3bPD_BwE

Grainier Industrial - Other mechanical operations: https://www.grainger.com/product/1U9...g!71851362079!

Dakota Cub - This is an old article. Not sure if they still offer these. There’s a phone number at the bottom: https://dakotacub.wordpress.com/2010...-sight-gauges/

[svyolo]

One of the sight gauges on the Granger sight had a shut off valve at each end. I don't know if that would satisfy Transport Canada or if they wanted the shutoff valves at the tank.

[davzLSA]

Ya know Rob even if these gauges are no longer available there are some great ideas here for making your own, thanks for posting this.

[Mark Goldberg]

There is another choice also. MSC Industrial part #G607-12-A-1-2. Order #56477755

That is what I had on my 4 place for many years. A little heavy and the actual tube is glass which would ruin your day if somehow you managed to break the glass. Mark

[Bcone1381]

For a review, Battson's fuel gage was written up in Beartracks, and his description is on post #14 on this thread. It uses AN822 elbows with 1/8" NPT threaded into PVC pipe.
https://bearhawkforums.com/forum/bea...el-gauge/page2

Screen Shot 2019-08-26 at 2.47.09 PM.png
Svyolo's comment #10.1 made me think a bit. (Whee can't see comments because he uses Tapatalk) I found that Aircraft Spruce has a 1/4 turn valve with a 1/8 NPT thread and 1/4" ID barbed hose end fitting that could replace the bottom AN822 fitting. It seems compatible for either a soft plastic sight tube or a rigid PVC sight tube.
Screen Shot 2019-08-26 at 2.37.08 PM.png
One more data point from McMaster-Carr that might instigate innovation. It has two valves. I think my house uses this valve for the outdoor water spigot. If it was applied to a Bearhawk it might give it the feel of a deHavilland or Grumman product.

Screen Shot 2019-08-26 at 2.15.35 PM.png

[JimParker256]

"The feel of a deHavilland or Grumman product." Priceless! But I really like Batson's sight gauge solution. Simple, light, and elegant.

[Battson]

There is an easy alternative.

You can put a black and white checker-board or striped pattern behind the gauge. Because of the different refractive indexes the pattern gets distorted, making the fuel level very easily seen at a glance or from a distance. This could easily be added afterwards.

GaugeGlass_StripeMarking.jpg

Or because the liquid is coloured, you can go without. It might just take a fraction longer to gauge the fuel level.

Remember that in most flights, the fuel in the gauge is sloshing around. You have to watch the fuel level for a few seconds to average it out, anyway.

[James]

Hi Jonathan,
I'm up to making the sight glasses, but because I haven't made the fuselage yet, I'm not sure how far they gauges should stick out from the wing root rib. Can you give me a rough estimate? 1-1/2", 2"?
I probably won't have much in the way of cabin trim at the wing root.
Thanks mate,
James

[Battson]

You will need to put the wings on and take them off again, at least once. When you do that, you can measure it based on your own setup and shorten the pipes to suit. I could give you a measurement, but you want to get it as accurate as possible. You can't cut the tubes or re-flare them with the wings installed anyway, you have to take the wings off.

[James]

Thanks Jono, yep that's exactly what I sort of had in mind, playing on the refractive index.
Elegant, simple, and uses basic physics to good effect :-)
If it shows up half as good as your diagram, that'll be fine for me.

I wouldn't have thought the standoff distance of the tube would make that much of a difference to the alignment of the stripes.
As for accurately reading the gauge, well if I can still see fuel sloshing around, I'm probably still ok :-)

Thanks everyone for the suggestions,
James

[Bcone1381]

I think its not uncommon to place a restrictor in the line to mitigate/dampen the sloshing effect.

[JimParker256]

Would that restrictor need to be in the lower port? Seems like the upper port would often (usually?) be venting air, which is notoriously good at escaping through even tiny openings...

[Bcone1381]

Yes, a restrictor in the lower port that restricts fuel flowing into the sight gage.