Pneumatics Question

On 25 May, 17:29, jsbrake wrote:
UH: When I pull up, the varios go up... both of 'em.

There's about 2' of silcon tubing in the circuit, all of it at the
panel end. *The second line of TE is silicon from the Y splitter that
I installed, so call that about 4' long. *The pvc lines end at the
central pedestal where the hood and panel are removable, so there's
silicon, then a 5-way quick-connector and then silicon to the
instruments. *I could probably remove about 4-6" of extra silicon, but
it gives me some "play" for being able to get at the quick-connect
without needing extra joints in my arms.

I'm not doing heavy g manoevers, maybe 1.5 g on a pull-up, perhaps
0.75 g on a push-over. *The most g I normally pull is during
thermalling turns.

I think I recall reading in the aircraft notes about a Brunswick
tube. *It appears to be factory made and the slots are well-defined.

An up indication no matter which way you push or pull isn't a matter
of degree of compensation. A few inches of squashy tube won't make a
difference and it sounds like you have relatively modest quantities.

I am puzzled why different manoeuvres have the same effect. It
somewhat suggests multiple pathology.

Two questions ref egg sucking. Pneumatic netto was common in the
seventies, presumably there is no cruise/climb switch in the plumbing
to the Winter?
When you did your leak test did you connect to the Brunswick tube? If
so did you remember to put a piece of wire (about .020") up the slots
and into the plastic test pipe to stop the pipe sealing around the end
of the probe?

Make an exact diagram of all the plumbing. It helps enormously in
keeping track and thinking about what effect a leak at any position
will have.

On May 25, 1:23*pm, Peter Gray wrote:
On 25 May, 17:29, jsbrake wrote:





UH: When I pull up, the varios go up... both of 'em.

There's about 2' of silcon tubing in the circuit, all of it at the
panel end. *The second line of TE is silicon from the Y splitter that
I installed, so call that about 4' long. *The pvc lines end at the
central pedestal where the hood and panel are removable, so there's
silicon, then a 5-way quick-connector and then silicon to the
instruments. *I could probably remove about 4-6" of extra silicon, but
it gives me some "play" for being able to get at the quick-connect
without needing extra joints in my arms.

I'm not doing heavy g manoevers, maybe 1.5 g on a pull-up, perhaps
0.75 g on a push-over. *The most g I normally pull is during
thermalling turns.

I think I recall reading in the aircraft notes about a Brunswick
tube. *It appears to be factory made and the slots are well-defined.

An up indication no matter which way you push or pull isn't a matter
of degree of compensation. A few inches of squashy tube won't make a
difference and it sounds like you have relatively modest quantities.

I am puzzled why different manoeuvres have the same effect. It
somewhat suggests multiple pathology.

Two questions ref egg sucking. Pneumatic netto was common in the
seventies, presumably there is no cruise/climb switch in the plumbing
to the Winter?

It did have pneumatic netto, but the plumbing was removed before I got
the ship. I still have the brass fitting.

When you did your leak test did you connect to the Brunswick tube? If
so did you remember to put a piece of wire (about .020") up the slots
and into the plastic test pipe to stop the pipe sealing around the end
of the probe?

I removed the Brunswick and connected directly to the stub sticking
out of the fin. Air flows easily through the Brunswick.

Make an exact diagram of all the plumbing. It helps enormously in
keeping track and thinking about what effect a leak at any position
will have.

Straight runs from point of opening (fin for TE/pitot, 2 in boom for
static) to the pedestal. From there, it's silicon to the quick-
connect and then to the instruments. Pitot and Static are both T-
split in the panel, the TE is Y-split under the seat. Nothing else in
the circuit. Pitot goes to ASI and VariCalc; Static goes to ASI and
Alt; TE to the varios; Capacity to the mech vario. Basic setup,
matches what I found on W&W and Winter websites about connecting
plumbing to instruments.

In the case of using a mechanical and an electronic vario - capacity
and no capacity respectively - and a glider in which the tubing aft of
the panel is not that accessible, I wonder whether just teeing and
having a 7 foot length of tubing to the vario would isolate the TE
line enough to minimize mutual interference. I accept that this would
add volume to the system, which may be a problem, and that the handful
of tubing might be a problem for space behind the panel.

Would this be a workable solution?

*Pitot and Static are both T-
split in the panel, the TE is Y-split under the seat. *Nothing else in
the circuit. *Pitot goes to ASI and VariCalc; Static goes to ASI and
Alt; TE to the varios;

OK not static. Sounds like cross talk between your pitot and TE
through that VariCalc's internals. Still an easy test- unhook it and
fly.

-Paul

On 25 May, 19:39, jsbrake wrote:
On May 25, 1:23*pm, Peter Gray wrote:



On 25 May, 17:29, jsbrake wrote:

UH: When I pull up, the varios go up... both of 'em.

There's about 2' of silcon tubing in the circuit, all of it at the
panel end. *The second line of TE is silicon from the Y splitter that
I installed, so call that about 4' long. *The pvc lines end at the
central pedestal where the hood and panel are removable, so there's
silicon, then a 5-way quick-connector and then silicon to the
instruments. *I could probably remove about 4-6" of extra silicon, but
it gives me some "play" for being able to get at the quick-connect
without needing extra joints in my arms.

I'm not doing heavy g manoevers, maybe 1.5 g on a pull-up, perhaps
0.75 g on a push-over. *The most g I normally pull is during
thermalling turns.

I think I recall reading in the aircraft notes about a Brunswick
tube. *It appears to be factory made and the slots are well-defined..

An up indication no matter which way you push or pull isn't a matter
of degree of compensation. A few inches of squashy tube won't make a
difference and it sounds like you have relatively modest quantities.

I am puzzled why different manoeuvres have the same effect. It
somewhat suggests multiple pathology.

Two questions ref egg sucking. Pneumatic netto was common in the
seventies, presumably there is no cruise/climb switch in the plumbing
to the Winter?

It did have pneumatic netto, but the plumbing was removed before I got
the ship. *I still have the brass fitting.

When you did your leak test did you connect to the Brunswick tube? If
so did you remember to put a piece of wire (about .020") up the slots
and into the plastic test pipe to stop the pipe sealing around the end
of the probe?

I removed the Brunswick and connected directly to the stub sticking
out of the fin. *Air flows easily through the Brunswick.

What that doesn't do is test the integrity of the joint between probe
and socket in the fin.