Elecromagnetic Tubular Solenoid Recommendations?

[Joe Lavery]

Mike, I just decided to have look at your website 757simulator.com using the link on your post. It was immediately blocked by Firefox as a potentially unsafe site. any idea why?

Joe.

[ame]

Mike, I just decided to have look at your website 757simulator.com using the link on your post. It was immediately blocked by Firefox as a potentially unsafe site. any idea why?

Joe.

The self-signed certificate was out of date. Looks ok now.

[Joe Lavery]

Mike, I just decided to have look at your website 757simulator.com using the link on your post. It was immediately blocked by Firefox as a potentially unsafe site. any idea why?

Joe.

The self-signed certificate was out of date. Looks ok now.

Ame, still a problem on my end:

[MistyBlue]

Got the micro linear actuator in.  Pretty slick little device.  12V applied one way and it extends an inch.  Reverse polarity and it retracts.  Internal limit switch stops the travel automatically when it reaches the limits.  Has a 5 LB holding force and it's a screw drive internal so it'll hold the force at any position without overheating. 

I probably won't use it as I think I have a solution with the solenoids when they get here.  But I may if I find the solenoids don't have the holding strength I need.

[ame]

Mike, I just decided to have look at your website 757simulator.com using the link on your post. It was immediately blocked by Firefox as a potentially unsafe site. any idea why?

Joe.

The self-signed certificate was out of date. Looks ok now.

Ame, still a problem on my end:

Ah. It works with http, but not with https, because the self-signed certificate is still broken. I hadn't realised that I was looking at the http version, so it appeared to be working.

[RayS]

From an old-timer:

I started using the EPIC (Was called EPIC-ISA) interface back in 1997, then upgraded to EPIC-USB a few years later.

I think it's still around. I sold off all my EPIC hardward though. Should have kept it in retrospect.

http://www.mindspring.com/~rrelect/prod.html

Ralph Robinson is the 'Inventor'. He is a retired telephone systems engineer and the EPIC system he designed contains a lot of telephone system DNA.

Probably the most robust platform available but the learning curve is steep.

I started a website in coordination with AVSIM.COM because quite literally, there was nothing online to help.

It's only found in Web archives now...
http://web.archive.org/web/20050213190218/http://bluesideup.avsim.net/

[Trevor Hale]

At Michael's request, he is no longer with us.

Thanks,

Trev

[Garys]

I guess he wasn't really joking after all.

[MistyBlue]

Bummer.  Didn't want to see anyone kicked out

Well, I took the solenoid that was in the RevSim for the trim wheel brake and used it to try out my modified RevSim parking brake mechanism.  Works like a champ.

I tied the solenoid to a Phidgets Relay card and used the Parking Brake release gate in Prosim. The brake lever is initially mechanically held in place by an arm attached to the solenoid.  When Prosim activates the parking brake release gate it fires the solenoid to push the arm out of position and hence "unlock" the parking lever, which returns to the OFF position by the parking lever spring.  Then, the solenoid returns to the default position (using its own spring) and takes the arm with it back to the "ready to set" location.  See pic.

I was having some issues with the power of this solenoid not being enough to release the handle in some other variations of the mechanism I tried.  By creating a longer arm the solenoid has to do less work to release the parking lever (better leverage) and so a weaker solenoid worked.

I'll be getting some stronger solenoids later this week but I can probably leave this where it is since it seems to work well. 

Some notes, in case anyone is interested in solenoids.  The big issue I see is they don't have a lot of initial moving strength.  So if you're trying to move something requiring a lot of initial force to move, you'll need a really BIG solenoid to do it. 

Also, the shorter a solenoid plunger moves, the more power it has.  As the plunger travels further, the power gets significantly weaker.  However, solenoids typically have much better holding power once they reach their design travel.  So if you need to move something in position and hold with some force (I'm thinking like the spoiler handle lockout to prevent lever movement to FULL during flight), a solenoid will work well for that.

Solenoids can generate a lot of heat when activated so if you need a solenoid to stay activated for a long period, a "continuous" solenoid would be best as it's designed for continual power.  Otherwise, short bursts lasting a minute or two would be handled fine by an "intermittent" solenoid.  From what I've read, anyway.  I don't claim to be an expert by any means.

Lastly, solenoid travel varies.  So if you need one, make sure you account for the plunger travel, and keep in mind the above...the further the plunger moves, the weaker the solenoid gets.

Hope this helps.  Later this week it'll be on to the other solenoids   Will keep you all posted.

[ame]

Hi Tony,

Your description of what you are trying to do is clear, and your proposed solution is sound. I will mention servo motors again as they might be a viable solution to some of your problems (whilst introducing their own problems, of course).

One thing to help your grey matter- think about central locking on cars. Initially, you might think that a solenoid would be the perfect solution to shoot the bolt inside the locking mechanism, however, it's done with tiny motors (which you can hear when the doors are locked and unlocked).

If you want to perform the same mechanical function as a solenoid then a short connecting rod to a slider can turn the rotary position of the servo motor into a linear position. In the software, if you have a Prosim variable with two states (on and off) you should be able to link those to two servo position values. The servo should go to either position depending on the state of the variable. The length of the servo arm and connecting rod, and the angle between the two positions will dictate the force and throw of the output.

A servo motor will consume a lot of current when there is a load on it, but not much when it is sitting in position. If you continue to supply timing pulses the motor will hold its position and push back against any force applied (it will draw more current when pushing back). If you stop sending timing pulses (if that's an option) then the servo motor will go 'slack' and can be pushed away from the last commanded position.

Unfortunately I can't find a document describing Prosim's Phidgets interface, but I haven't looked that hard yet.

[MistyBlue]

Thanks for the servo explanation!  Makes sense and I need to try it out so I can add that to my toolkit for options to use.

The solenoid thing is working out quite well so far.  I got some new, larger solenoids to operate my Sync Locks and they work perfectly.  They overcome the strong spring strength and hold for quite a while without hardly any heat.  I attached a picture of how it is set up.

So to help those not make the same mistakes I did in selecting the right solenoids, I'll try to interpret how I went about selecting the Sync Lock solenoids for those of you interested.  I'm attaching a couple of pictures of what the solenoid spec sheet looks like for the solenoids I selected. 

On the Page1 image you'll see I have highlighted some areas which were what I used to determine what to use.

The first row, Maximum Duty Cycle, is how long you expect the solenoid to run for as a percentage of overall usage.  So if you have a solenoid that is powered for 30 seconds and cools off for 90, then that is a 25% duty cycle.

However, the Maximum ON time is the maximum amount of time you the solenoid should be powered at a time without creating too much heat and excessively wearing the solenoid.  This value overrides the maximum duty cycle.  So that's a better value to use when spec'ing out the solenoid. 

So, in my case I was looking for the strongest 12V solenoid where it wouldn't be on for more than 60 seconds at a time (the Sync Locks only activate during the landing rollout).  The 60 seconds max ON time perfectly meets my needs, and that equates to a 25% duty cycle solenoid.

Now that I have that value, I look down the 25% column for a VDC value as close to 12V as I can find.  In this case 13.6V is the lowest value they make at a 25% duty cycle.  So that means the solenoid won't produce quite as much power since it's rated at 13.6V and I'm putting in only 12V, but it also won't get hot since I would be under-powering it.  13.6V translates to an AWG of 23 (very left column across).  So, my part number would be 174419-023.

Last thing to check is the actual power tables on the Page 2 image.  You'll see I highlighted the 25% Duty Cycle line in the Typical Force diagram.  I know I only needed about 0.3" of plunger movement so that equates to about 5 Force-lbs (22 Newtons) of force.  Actually a little bit less since I'll be under-powering the solenoid.  But you get the idea.

It helps to know how much force you'll need.  If you've got something pushing/pulling against a spring, try to find a way to measure the force required to move the spring.  A fishing scale works.  I used a hand-held luggage scale.  Attaching it to the mechanism I want to move I can get a reading of how much it takes to move the thing.  For my Sync Lock springs, it was around 2 pounds if I recall, so 4-5 lbs force of this solenoid at 12V is plenty.

Something else you might also need to consider is holding force if you need to maintain a force against something for a while.  On Page 1 of the attached pic you'll see a Holding Force value of 9 Lbs (right side).  That's nice and strong!

Hope this is useful!  It was an education for me

[MistyBlue]

Quick update.  I now have four total solenoids in place.  Two to operate the thrust reverser lockouts (sync locks), one for the parking brake release, and one for the spoiler handle lockout.  Powered by a PhidgetsInterfaceKit 0/0/4 relay card.  Quite happy with the results and operation so far.