Instruments for the pax in a tandem seating aircraft

[Rob Swain]

Here's an issue I can't remember ever reading anything about: in a tandem seating aircraft how does one get feeds for the basic instruments that are in the 'passenger' seat?
By tandem aircraft I'm thinking of one that has 2 instrument panels like a Starduster Too, S2 Pitts or Van's RV8, and not like a Piper Cub where (I think) you just look over the shoulder of the bod in front.

Oh yes: we are talking dial instruments here. We can't stretch to the simple approach of buying a pair of Stratomaster or Dynon screens, although electric dials with senders on the engine etc are probably within budget. Screens would look odd too, in an open cockpit biplane.

I'm particularly interested in the essentials like tacho, ASI, fuel and manifold pressure etc.
For an altimeter I would expect to just include it in the static system, but am I correct even in this assumption?

[J.C.]

Why are they essential?

[macconnacher]

I agree with John. In the early Moths they had a big glove compartment an altimeter, compass and a clock and sometimes an ASI and a simple slip ball. All of which can be fed off the pipework to the main cockpit.

You just need enough to keep the passenger from getting bored!

[Rob Swain]

Why are they essential?

So the bod in the front can fly the bird should the need arise. The owner of the beastie in question is only still with us because he was able to fly and land the thing from the pax seat, so he understandably has very definite opinions on the subject.

The Moth arrangement mentioned above sounds like what we are trying to achieve here but dispensing with the clock and gaining the necessary instrumentation for the variable pitch prop the aircraft is sporting (manifold pressure?).

So it's possible to run 2 ASIs off a single Pitot then?

[macconnacher]

A Tiger Moth does it; speed is a differential pressure measurment not an airflow mesurment, I guess manifold pressure can be doubled up. Also Westac make a small cheap electronic rev counter that picks up off the magneto - used with VWs on Monoplanes and Turbs which would be ideal for a backup.

[Sandy Hutton LAA372]

I agree with John. In the early Moths they had a big glove compartment an altimeter, compass and a clock and sometimes an ASI and a simple slip ball. All of which can be fed off the pipework to the main cockpit.

You just need enough to keep the passenger from getting bored!

So how do you go about piping in the Compass, Clock and Slip Ball?

[Rob Swain]

At the risk of being thought awkward (although when has that ever stopped me?)...

Electronic Tachs that work off the P lead on a magneto: are they all for 4 cylinder engines, or are they switchable for 6 cylinders (Lycoming IO-540), or is there a different version of the tach for that?

Yup - the beastie in question has 250HP up front!

[Steve Brown]

Sandy - a couple of mirrors or prisms!!!

Rob - electronic tachos are often configurable to different nos of cylinders etc but not all are.

You could impulse one tacho from one mag p lead & the other from the other.

The MP line can be tee's off with no problems/losses, as can the static & pitot lines for Alt, VSI & ASI etc though I'd draw the line at teeing the fuel pressure (though it would work) as it is one more thing to go wrong. At least asking teh teh FP is would keep the P1 / P2 conversation going!

Regards
Steve

[macconnacher]

Sandy

The problem of writing a reply when your wife has cooked the dinner and wants you to eat it NOW; then editing it and adding a couple of instruments such as compass and slip ball.

[cardiffrob]

If you can't find a 6 cyl tacho, just make a note by the tacho that the take-off rpm is now (Standard x 1.5) rpm?