Sunday, August 29, 2010

What Is Odd About This Panel?

You know I love to look at instrument panels, and that I go crazy over unusual or clever instruments. Here's a panel I saw recently. There's nothing particularly unusual about it, but the sum total is a little odd. I never would have guessed what it was, but I'm sure Cockpit Conversation readers will.

What am I sitting in as I take this picture? It is not an instructional aid or a museum piece. It is a real, installed engine instruments panel connected and working.

There will be a hint in the next post.


Ihab Awad said...

I notice there is only 1 starter button, but two RPM gauges.

TgardnerH said...

As Ihab noted, there's only one starter, also only one Oil Pressure, Manifold Pressure and Fuel flow. Also, I'm sure there's a more logical conclusion, but to my non-aviation eyes the fuzzy label directly under "Left Tach" looks like "shower."

Wayne Conrad said...

I don't know that aircraft panels are mounted in boxes formed with...what is that, 1/2"? 5/8"? ply... that stuff is heavy. I'm going to guess that this panel is part of a ground installation of some sort.

The mirror-images tachs are neat. I don't know enough about aeroplanes to know if that's unusual.

"Shower?" Hmmm.

Sarah said...

"Shower" refers to "Shower of sparks", or ignition boost. This is used at start up of radial engines with a particular kind of magneto.

One starter button could be a red herring - maybe one of the unreadable switches flips between starting #1 and #2. I'm guessing this is DC-3 vintage or earlier, obviously a twin.

But maybe a twin engine boat - nothing here looks very airplany, as others have noted the wood housing for example.

Others will correct and educate me, I'm sure.

Matt said...

Okay.. Absolutely wild guessing:

Is it an instrument panel for a fuel pump cobbled together from aircraft instruments?

How I got there:

The disparity between the runtime on the left and right pumps (assuming that's what they are) is huge - even if the left one has rolled over. So maybe they're for different fuels (though you'd think the labels would say that)?

Also - the pressure/flow gauge has been relabeled "manifold fuel" which makes me think that the 30" pressure might be fuel pressure, not engine manifold pressure. The oil pressure/temp gauges are no help as they're zeroed - maybe not connected since we aren't actually looking at an engine?

As far as the note for checking gas, in my alternate fantasy world that's because the pump runs on 87 or diesel not 100LL.

I'd love to know what the label under the center toggle says, but given that we can't see it, I'm guessing it wouldn't help.

Good challenge. I'm stumped.

Matt said...

Gah. Figures that right after I actually write all that I see two or three things that would make it impossible. I couldn't read the "left mag" / "right mag" labels. So - actually engines. And since they're off, so are the engines which explains the oil pressure (but doesn't explain the manifold pressure still being up). I like'd Sarah's guess, but since I think that's a wooden wall stud in the background, I'm betting this is in a shed somewhere doing something.

Anyway - really good one.

A Squared said...

My guess: it's an engine test stand in a Maintenance/overhaul facility.

Two tachs, one for testing normal right turning engines, one for testing left turning engines (hence the left and right turning tachs)
Left turning engines are less common, hence fewer engine test hours one the left turning tach.

An engine manifold pressure gauge at rest or disconnected will read atmospheric pressure, approx 30" hg.

Matt said...

A Squared - that makes an awful lot of sense. If that's true, I wonder why there are two mag/shower switches though. You'd think you could use one for whatever engine you were testing.

And yeah - duh on the 30" thing. I see a needle "up" and assume something's happening (not the suction that'd pull it back down that's not happening). (re)learn something new every day. :-)

GPS_Direct said...

Yeah, the label below "Shower" says "of Sparks."

The left hand white gauge looks to say "Metered Fuel."

Based on this and the "??TP&CM? Power" switch at the bottom right, I'm going to agree that it's some kind of fuel transfer vehicle. But, one running on radial engines?

Matt K. said...

The shower of sparks system is used on non-radial engines too, although the impulse coupling is more common in my experience.

I like the engine test stand theory. Makes the most sense to me. Explains pretty much everything but the SCAT tubing on the left. I've got no idea what that would be for.

Matt said...


I think that one reads closer to "??TP&CHT Power" (no clue on the ??TP bit). I assume the CHT and EGT transducers need some power to get readings (especially since thats a digital gauge in the upper right). So, that might just be power for the instruments that need it (stand in for the avionics bus).

That lends more weight to the test stand idea. However, I have no idea why a test stand would require a defroster or heater. Though, if this is in Alaska, I suppose it might be necessary.

dpierce said...

Clearly, someone has built an Alaska-grade snowblower by mounting a couple of Yaks to the top of a truck. Aviatrix found this in a local "Things Gone Horribly Wrong" museum.

A Squared said...

Like Matt K said, shower of sparks is not used exclusively on radials. My guess is that an engine test stand would have controls to operate any combination of ignition systems, single shower of sparks, dual, or none at all (with impulse couplings)

When setting up a newly reassembled engine, with fuel injection one of the things you'd have to do is adjust the fuel flows. An accurate fuel flow meter would be a useful item to have. GA fuel flow gauges (like the one on the right side of the MAP -Fuel Flow instrument) typically do not measure fuel flow, but rather fuel pressure through a venturi. That is a function of fuel flow only if another set of variables are true. They aren't always true, and in setting up a new engine or troubleshooting a sick one a real fuel flow gauge is handy.

A Squared said...

The scat tube I have no idea, other than to pit out that it is an assumption to say that it is a part of the panel setup. Might be something else entirely

John Lennerton said...

What is the "Defrost" switch for? (to the left above manifold pressure)

How would that be used in an engine test stand?

We need more pixels!!!

I like dpierce's idea of twin Yaks for snow clearing!

GPS_Direct said...

@Matt - I thought about the CHT Power, but wasn't thinking about the digital gauge needing power outside of a "master."

Of course, we've all ignored the "Fast Gem Slow" lever/knob. When I first saw that, I was leaning towards the snow blower idea, as it reminded me a a power-takeoff (PTO) from a truck or tractor. But a snow blower wouldn't need a "Fuel Transferred" gauge.

A Squared said...

What is the "Defrost" switch for? How would that be used in an engine test stand?

Well, initially, when I thought of "test stand" I was thinking of a stationary application in a building, but in trying to fit the pieces together, I can think of one test stand which is actually sort of a vehicle with an enclosed cab. The engine is mounted on a mount on the front and the whole contraption is parked on the ramp outside the shop for engine runs. A setup like that might have a defroster for engine runs on cold, and/or humid days.

A Squared said...

But a snow blower wouldn't need a "Fuel Transferred" gauge.

Which one looks like a "fuel transferred" gauge to you? Of the two gauges with white faces, the left seems to me to pretty clearly say "metered fuel" and the one on the right, the left of the label is completely unintelligible to, except for the last word which looks like either "Fuel" or "Full" to me.

If it's not a test stand, the only applications I can think of in which an aircraft engine is likely to be used are a hovercraft or an airboat.

Wayne Farmer said...

A Squared - regarding your guess of hovercraft, could "GEM" be "Ground Effect Motion"?

[Wikipedia also suggested "Graphite-Epoxy Motor". :-) ]

John Lennerton said...

How about this:
Click Here

A Squared said...

A Squared - regarding your guess of hovercraft, could "GEM" be "Ground Effect Motion"?

Well, a few decades back, hovercraft were often referred to as "ground effect machines" and that certainly crossed my mind looking at the "GEM" in the photo. I haven't seen anything else in the photo which suggests hovercraft to me though.

Wayne Farmer said...

Based on what we have so far, I'm guessing it's a hovercraft, with two counter-rotating propellers, designed to transport and transfer fuel by traveling over frozen rivers in Alaska or Canada.

GPS_Direct said...

@A Squared

Sorry, wasn't looking at the picture when I typed that last, and my mind turned "Metered" into "Transferred."

Metered fuel pressure can be part of radial engines, so maybe the shower of sparks button isn't too far off.

Maybe a test stand is in the picture and the seemingly dual engine gauges are the red herring. There are only one set of mag switches. And, there are portable test stands - kinda like yellow gear on carriers - that you wheel out and then tie down (using chains) to the padeyes to do your run up and testing. The operator stands in a cab behind the engine with a windscreen, so the defrost (especially in AK) isn't a stretch.

Still pondering "GEM" though...

A Squared said...

Metered fuel pressure can be part of radial engines, so maybe the shower of sparks button isn't too far off.

You may have overlooked a couple of posts. Shower-of-sparks isn't a radial engine feature, necessarily. the term "Shower of sparks" is actually a Bendix trademark for ignition boost, and I've only heard the term used in conjunction with the magnetos of horizontally opposed engines. On the radial engine airplanes I've flown, it was merely called "ignition boost". Same basic system, but lacking the Bendix trademark