Van's vs UMA model numbers for air speed indicator.

Hi all,

I would like to replace my steam gauge Air Speed Indicator (ASI). The one that came with the airplane has the units of MPH and I want to change that to knots.

The present gauge is a 2 1/4" diameter instrument and I want to replace it with a 2.25".
IN the following picture, it's the second gauge from the right in the lower right hand corner of the picture:



First I looked at the Van's web page and I see this:

IF UMA-16-211-242 7/8 KNOTS NONE NO UMA (2.25")

(the NONE and NO means no light and no inner scale).

Ok that looks good.

I look on the UMA page to get it's dimensions and see how it looks and I see this:

16-210-240 40-240 MPH -
Above ranges are available in Knots.
Part number changes to 16-211-XXX

Ok so it looks like I want the 16-211-240 from UMA But Van's calls it a 16-211-242.


1. Why does UMA have different model numbers than Van's? Is it the same device? Why does Van's call it a -242 and UMA calls it a -240?

2. If you look at the present instrument in the panel picture above, it looks like the "flange" is behind the panel. That suggests to me that the flange is threaded. Is that correct? On the UMA there seems to be a substantial flange and it looks as if it goes on the front of the panel.

- there's room for the flange around the instrument on the panel. I can use nuts and bolts, Perhaps the flange is the same on the one I have in the airplane but it's just behind the panel.

- When I do a web search on the 16-211-240 it looks just like the -242 as regards the flange.

I measured the distance between the mounting screws on the airplane and they match the UMA installation picture. for the UMA -240.

I do not know whether to order the Van's -242 or the UMA -240

Any suggestions?

Thanks!

This is a pure guess. Vans are marked for the specific model with colored tape for V speeds. Perhaps that is the only differnce?

JonJay said:

This is a pure guess. Vans are marked for the specific model with colored tape for V speeds. Perhaps that is the only differnce?

Click to expand...

Hmmm good guess. And even if it's not precisely the explanation between -240 and -242, I'd want the Van's speed tape marking wouldn't I?

Thanks!

Changing Airspeed Indicator

I'm considering this too.

Currently I have my EFIS set to MPH and my ASI has MPH on the outer ring. Then my GPS Navigator and my 696 are both in Knts so I have that too.

BUT, I'm strongly considering switching my steam to Knts only and flipping my EFIS switch back to Kts so I'll be all knotted up.

My theory: If my PFD fails and I'm using my backup ASI, I don't want to have to look at the little inside ring or think about which units I'm using.

Thoughts?

rolivi said:

I'm considering this too.

Currently I have my EFIS set to MPH and my ASI has MPH on the outer ring. Then my GPS Navigator and my 696 are both in Knts so I have that too.

BUT, I'm strongly considering switching my steam to Knts only and flipping my EFIS switch back to Kts so I'll be all knotted up.

My theory: If my PFD fails and I'm using my backup ASI, I don't want to have to look at the little inside ring or think about which units I'm using.

Thoughts?

Click to expand...

That's similar mine is set up: EFIS and Steam on MPH but GPS and sectionals in knots.

I bought the Van's ASI for the -8 calibrated in knots. Looks like I need a couple of AN840-4's for the install. I have to double check the present installation. If the tubing is 1/4" then I have the AN840's and it's a quick install.

If anyone has a 2 1/4" ASI in MPH, marked for an RV-3/4/6, I'd be interested in it. Send me a PM.

Thanks,
Dave
RV-3B now on the fuselage

I don't think it is a bad idea to have both. The conversion is pretty simple to do in your head. You may find yourself in a different airplane at some point, with different instrumentation. It isn't a bad skill to have.
I go from mph, to knots, and then to klick's with the Bucker (a bit harder to do in my head, but I cross the numbers at 100K, which makes it easy math.)