Re: Open Spoilers Alarm on tow

[tango4]

Microswitch on release mechanism, microswitch on brakes. Pressure switch (
very low! ) in ASI circuit

Bistable arming circuit with 15 minute timeout.

Arm circuit with leading edge of tow activation. ( Open release to install
hook, circuit goes active )
While armed if brakes are opened buzzer goes off.
Circuit is disarmed when 40kts reached.

Ian

[Uri Saovray]

Jim,
So you are suggesting to measure the force on the tow tope, assuming
it would rise dramatically if the spoiler is open?
Sounds like a good idea, but:
1) Will it trigger in a ground launch? Won't opening the spoilers
REDUCE the load?
2) Would it trigger when the handle is just unlocked, and the spoilers
aren't actually out (yet)?
Uri

(Jim Vincent) wrote in message >...
> > What about the towhook? Magnetic sensor? where? How? Other ideas
>
> Install a strain gauge internal to the fuselage right up against the hook
> mount. Get Peter Masak to design a simple circuit that trips an electronic
> relay when the strain exceeds a certain amount. Knowing Peter, it should take
> him less than an hour.
>
> Jim Vincent
> CFIG
> N483SZ
>

[Bob Lepp]

I'd go for 'spoiler open' alarm sounding when open IF my hand is not
on the actuator. On tow or off tow, if they are open and I did not
open them I'd want to know. I've had both situations happen. My fault
both times.

Might make wiring a bit simpler.

Bob

(Jim Vincent) wrote in message >...
> > What about the towhook? Magnetic sensor? where? How? Other ideas
>
> Install a strain gauge internal to the fuselage right up against the hook
> mount. Get Peter Masak to design a simple circuit that trips an electronic
> relay when the strain exceeds a certain amount. Knowing Peter, it should take
> him less than an hour.
>
> Jim Vincent
> CFIG
> N483SZ
>

[Jim Vincent]

>I'd go for 'spoiler open' alarm sounding when open IF my hand is not
>on the actuator

I'd rather have my hand near the tow release instead, especially during the
first part of the tow.

Jim Vincent
CFIG
N483SZ

[Jim Vincent]

Uri,

The strain gauge would just indicate that the tow rope is under any load,
regardless of the amount, but triggered above some reliable value, perhaps 5
lbs. This would indicate that the tow hook is being used.

Jim Vincent
CFIG
N483SZ

[Andy Durbin]

Somewhere in this thread someone said "the microswitch on the airbrake
handle is the no-brainer part".

Detecting the handle position gives no protection for deployment of a
disconnected airbrake.

Cambridge 302, and I think L/S Navs, include a takeoff airbrake open
warning based on airspeed. It works well, but would need 2 in-wing
sensors to detect an open disconnected airbrake.



Andy

[Mark James Boyd]

Jim Vincent > wrote:
>
>I'd rather have my hand near the tow release instead, especially during the
>first part of the tow.

Most of the gliders I've flown have the tow release way
too far from my hand. Granted, I have short
arms (not a boxer), but do others commonly notice they
need to lean forward a little or twist shoulders to
pull the release on many gliders?
--

------------+
Mark Boyd
Avenal, California, USA

[Jim Vincent]

>Most of the gliders I've flown have the tow release way
>too far from my hand. Granted, I have short
>arms (not a boxer), but do others commonly notice they
>need to lean forward a little or twist shoulders to
>pull the release on many gliders?

Get yourself a ski boot carrier. Its a length of 1/4" nylon cord with a
plastic handle. Wrap the cord around the existing release knob, and Voila, 8"
extra reach. Works great in my Jantar where the existing release is way
forward. Another benefit is I can loosely hold the plastic handle in my hand
with little risk of pulling the release by accident if I hit turbulence since
there is a lot of slack.

BTW, IMO, your hand should never be holding the release on the panel.
Instead, keep your hand just behind the release, basically with your knuckles
touching the release. This way, if you're waved off, you don't have to look
for the release, it is already at hand.





Jim Vincent
CFIG
N483SZ

[Bob Lepp]

>
> I'd rather have my hand near the tow release instead, especially during the
> first part of the tow.
>

Me too, what I meant to convey was.... if the spoilers are open and my
hand is not on the spoiler control handle it might be nice to have an
alarm sound. To me it matters not whether there is pressure on the tow
hook or not. It only matters that the spoliers are open and I am not
holding them open. I guess I'm thick, I haven't caught on why tow hook
pressure is important.

[Jim Vincent]

>Me too, what I meant to convey was.... if the spoilers are open and my
>hand is not on the spoiler control handle it might be nice to have an
>alarm sound.

Interesting approach! I like it. Could easily be done.



>To me it matters not whether there is pressure on the tow
>hook or not. It only matters that the spoliers are open and I am not
>holding them open. I guess I'm thick, I haven't caught on why tow hook
>pressure is important.

Tow hook pressure was one parameter discussed in a spoiler warning solution.
Frankly, I like your idea of the hand sensor more.

Jim Vincent
CFIG
N483SZ

[Bill Daniels]

"Bob Lepp" > wrote in message
om...
> >
> > I'd rather have my hand near the tow release instead, especially during
the
> > first part of the tow.
> >
>
> Me too, what I meant to convey was.... if the spoilers are open and my
> hand is not on the spoiler control handle it might be nice to have an
> alarm sound. To me it matters not whether there is pressure on the tow
> hook or not. It only matters that the spoliers are open and I am not
> holding them open. I guess I'm thick, I haven't caught on why tow hook
> pressure is important.

If I understand your proposal for a sensor to detect the pilots hand on the
spoiler handle correctly, it should fulfill the "spoiler open on tow"
warning function assuming no pilot would deliberately open the spoilers
while still on tow.

I do see a few problems that need a thoughtful review.

I have had pilots open the spoilers instead of pulling the release at the
top of a winch launch. A warning here would be nice.

It would create a problem if the pilot must move his hand from the spoilers
to the flaps to select a negative setting just after touchdown to maintain
aileron control. It would be a real nuisance to get a warning horn at that
busy moment.

Some gliders must start their takeoff roll with the spoilers open to augment
aileron control at low airspeeds. Again, it's a bad time to be distracted
by a audible warning. This is where a low airspeed lockout would be needed.

I think the system would need three sensors to give a useful warning -
airspeed above a certain value, ring in hook and spoiler open.

Bill Daniels

[Bob Lepp]

Good points.

> I have had pilots open the spoilers instead of pulling the release at the
> top of a winch launch. A warning here would be nice.

The 'Spoilers Open' alarm sounding means 'your hand is opening the
spoilers', since the other hand should/must be on the stick...let the
pilot figure out the rest?

>
> It would create a problem if the pilot must move his hand from the spoilers
> to the flaps to select a negative setting just after touchdown to maintain
> aileron control. It would be a real nuisance to get a warning horn at that
> busy moment.


This is a 'good thing', not a problem. If you're on the ground, a
'spoilers open' alarm can be ignored, just as I ignore the audible
stall warning horn on my ship. In fact I listen for it and worry if it
does NOT sound. Like checking warning lights for not being burned out.

>
> Some gliders must start their takeoff roll with the spoilers open to augment
> aileron control at low airspeeds. Again, it's a bad time to be distracted
> by a audible warning. This is where a low airspeed lockout would be needed.

Ditto above, to me at least, I expect the alarm and want the alarm to
prove the alarm system is working. My stall warning on/off switch is
placarded as such, 'Switch on before takeoff' for that purpose I
believe.

>
> I think the system would need three sensors to give a useful warning -
> airspeed above a certain value, ring in hook and spoiler open.

Sure, that works well, then when they pop open just after you
release..... or after you forget to relock them after using them for
an in flight height reduction.... I have done this, it is
embarrassing!... at best.

I can't see how any of the proposed combinations could be a bad thing.
It just depends on cost to install, complexity and reliability I
guess. Heck, I don't even know how to sense the hand on the control
reliably! So a device to sense ring in or strain on hook boggles me. I
can see they would be expensive, tricky to do and likely cause some
paperwork for the authorities. But if they prevent one accident.....

>
> Bill Daniels

[Marc Ramsey]

Bill Daniels wrote:
> I think the system would need three sensors to give a useful warning -
> airspeed above a certain value, ring in hook and spoiler open.

If you add a $2 microcontroller to the system (or are clever with
relays) you could use a switch to sense that the release has been
pulled with airspeed above threshold, rather than trying to determine if
there is a ring in the hook...

Marc