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Reverse thrust mechanism

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Hi allAnyone have any ideas on how to simulate reverse thrust mechanism on a seperate axis , eg 2 main axis for engines 1&2 forward power and 2 seperate axis for engine 1&2 reverse. I dont have EPIC but do have aerosoft MCP which adds 16? extra joystick axis.I was originally thinking of using a couple of microswitches wired to the Kboard card on F1 & F2 but dont want to use this method as it is too crude.Pete dowson said to use 2 wipers per throttle wired in series but i couldnt get this to work as 1 wiper would be down at 0 ohm which would cut the other wiper out totally.I probably did not understand what he was trying to explain to me! Anyone solved this or has any ideasthanks keith

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Guest Stephan Haas

Keith,Did you have a look at the latest FSUIPC? Pete now has some extra options for reverse thrust.Kind regards,Stephan Haas

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Guest GeorgeDorkofikis

Putting 2 pots in series is a very nice solution and the one I was thinking to apply to my design when I finally find the time and parts to do it.You don't have to zero the main throttle pot.Try this. Main throttle pot 50K Linear and another pot 50K linear for the reverse thrust. You connect them in series. When you calibrate you set the motion from full fwd to full reverse. Then from inside FSUIPC, you set the range for normal throttle from full fwd to idle normal...And.. that's it! The rest will be reverse... And can be variable reverse.George DorkofikisAthens, Greece

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Thanks for the input , I have looked at the fsuipc setting but it seems this is one axis for all engines? I may be wrong. George thanks for explaining it, i think i see what is meant now,eg you dont use the full range of the wiper for forward .thanks keith

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Hi guysYour solution is the one I intended to use, George. The one thing I haven't worked out yet is how to prevent the main power lever moving forward when reversers are "active" and vice versa.It could turn out to be a little messy if you apply the reversers at 50% main power or pushing the throttle levers forward when reverser levers are pulled.Maybe some mechanical stops could be applied?

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>Hi guys >>Your solution is the one I intended to use, George. The one >thing I haven't worked out yet is how to prevent the main >power lever moving forward when reversers are "active" and >vice versa. >>It could turn out to be a little messy if you apply the >reversers at 50% main power or pushing the throttle levers >forward when reverser levers are pulled. >>Maybe some mechanical stops could be applied? How do the reversers actually work? I thought the reverser handles just open the "reverser" and you either brake with idle power (which apparently is what you have to do in urban airports etc because of noise restrictions) or you open the reversers and push the throttles forward to get some more power to the engines (and the reverser just reverses the thrust) Do reverser handles in themselves adjust the throttle?So this idea seems interesting (two pots in series) but I am just wondering how those work in reality..?Tuomas

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Hi Tuomas et alHere's an excerpt from the PIC767 forum about the 767 throttle and reversers. It's quite technical but I'm sure you'll get the point:Regarding Autospoilers.... As previously stated on the old website, there are inputs to the Autospoiler control logic from both the Air/Ground system (i.e. tilt sensors on the mainwheel bogies) and the Reverse Thrust Levers. There are microswitches hidden inside the thrust levers in the cockpit to provide this logic. The microswitches are activated when you pull up on the reverser levers. The angle at which the switches are activated varies somewhat depending on the aircraft installation (Factors include engine type (FADEC/non-FADEC), aluminium levers Vs titanium levers, etc). For example, a CF6/aluminium/non-FADEC setup may trigger the microswitch from reverse thrust lever angles ranging from 10 to 26 degrees from the fully down position (The reverser levers have a total range of approximately 113 degrees on 767's with non-FADEC engines. The FADEC engine type levers may only have a range of 88.5 degrees (cockpit builders take note here )). These very same microswitches also "set the wheels in motion" for the reversers to deploy (on the engines).The higher you pull up on the reverser levers, the faster the engine will run... and the more reverse thrust you will get. However, if you yank on the levers really quickly, you will find that you hit a stop which is far short of the maximum travel of the lever. This is temporary, however (It simply allows the reverser mechanism on the engine to get into the right position.... before you give it "hell". The stop will release when the engine reverser mechanisms have deployed by a certain amount (again, this varies from aircraft to aircraft. A typical 767 value is 76% deployed). The lever temporary stop angle also varies from airplane to airplane (e.g. 42.6 degrees).To employ all these facilities would really be a challenge! ;-) "As real as it gets" huh?Regards

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Guest GeorgeDorkofikis

The reversers have two stages. The unlock stage and the actual power increase.By the use of a microswitch you can simulate the 'unlock' phase very nicely. Electronic schematic attached.I could go very deep and explain, but I think a picture is better than 1000 words. :-)If you need any clarification, just ask!I think I forgot to include a small capacitor 50nF should be more than enough, value can be experimented, between the microswitch contacts 1 & 3. The capacitor will serve as a backup for the msec that the switch might be in a neutral position and therefor the whole circuit whould return null value.It's been years since I last 'played' with electronics, but I think is funtamental and you don't forget so easily.. :-)Edit....This way will work taking as a fact that Max Thrust will be 150KOhm on the Pot, Idle Normal will be 50KOhm, and MaxReverse will be 0Ohm (zero).EditEnd... :-)George DorkofikisAthens, Greece

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GeorgeThat looks like a really doable solution. It took a while to figure it out. As for you, it was ages since I dug down into electronics. ;-)Wouldn't it be possible to have a three pole (3PST??) micro switch and drive two relays/coils to mechanically lock the throttle levers and unlock the reverser lever? Just an idea, don't know how to implement it yet... :-)Cheers

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Guest GeorgeDorkofikis

Yes, the use of relays should be relatively easy to implement...They can move simple metalic bars that would restrict movement...Yes... should work...Now... If I could only find some drawings of the throttles themselves, I could start building mine!!! Geee... How simple stuff can be so hard sometimes!George DorkofikisAthens, Greece

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George This is as far as I've come with my 737 pedestal. Using autoCad to be able to get some dimensioning for production. Planning on using 13mm and 26mm wooden board and 1mm sheet metal for the housing. A lot of drilling and routing...lol. And there's a lot of things this pedestal has to house. I am a bit worried about the space.All dimensions is taken from photos and assorted pictures, and I think it's looking ok. But this is merely a draft.Regards

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Guest GeorgeDorkofikis

WOW! :-eekMan, you are going far! Unfortunately I don't have that much space, and certainly not the money :-) to do a complete pedestral, so for now I will just go for the throttle levers only.My main problem are the part supplies. Ok, I can find the wood easily. But aluminium sheet is hard to handle and certainly not easy to cut.Also, electronics are getting pretty 'exotic' here lately! Few years back I could find 10 or 15 different potensiometer qualities with variances from size to axis diameter etc... Nowdays I'm luck if I even find linear pots of required resistance!!!Anyway, going completely off topic here... I'll post another msg for this.George DorkofikisAthens, Greece

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Guest seev_39

Hi George,I found it very useful to work with old computer case material (you will get it for nothing). This is a kind of soft steel that can be easily cut and bend. You cut the material with a jigsaw (be careful to protect your eyes) or even with steel scissors and drill holes with a normal hand drill. Another advantage, the material gives you good shielding when a wire is attached to ground your rack to your PC. It also has a nice gray color and doesn't need repainting.As for parts like throttle handles, gears, knobs, etc. I cast them from polyurethan. The process is simple; make a mold from artificial clay, something we used to do when kids. then cast artifical rubber over it (it is a mix of two materials) and then take the mold out and cast the polymer instead (it is also made by mixing two materials). I am sure you can find the needed materials in a chemical supply shop or a hobby shop or a boat workshop - they use those materials a lot for repair. Another good material for making small solid parts is steel reinforced epoxy putty, which come in a tube. This is the secret weapon of choice of plumbers. It cost them three dollars and they charge you for a hundred. You mix it, make your part and let it harden. then you can file it, drill it, etc. It is hard like steel and sticks to everything when still soft.Seev

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Hi Seev, Welcome to the forum. Molding and casting sound like a good way of getting those difficult handle shapes done. Do you have any pics showing the results? Would be nice to see what can be done with this method. RgdsRoland

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Guest GeorgeDorkofikis

Hi SeevYeah... Molding is a very nice idea... and the computer case another good one too!... And I can get plenty for free.Let me see if I get it right...1. You make a prototype from clay, shape it as required.2. In a box or proper container you affix the prototype (when dry of course), and you fill the box with the artifical rubber.3. When dry you carefully remove the whole from the container and carefully detach the clay prototype from the (now dry) rubber.4. You use the rubber as a mold and fill it with the polymer.5. When dry, you got your part!Is that right? Did I miss something?George DorkofikisAthens, Greece

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Guest seev_39

Hi George and all,You got it right. Need is the best incentive. Me, like yourself George, live in a place where technical supplies are scarce and expensive and that was the couse for looking into different possibilities.1. Making the parts is done the way you put it above. You have to be carefull about the artifical rubber mold. It is flexible and must be placed back in the box where you casted it the way as you began with, otherwise you get the final product distorted.2. I attached 4 pictures. One of them show gear wheels with a 1:3.5 ratio for throttle and triming (throttle handle moves 70 degrees while pot rotates 250 degrees). In the trim the ratio is opposite. The wheel rotates more then three times while the pot rotates once. I think this is a good ratio because the active part of the trim is very limited.How I did this wheel, please don't laugh. I took two plastic container tops with suitable diameters, cut out 8 mm steel strips from a cucumber tin container and bent the teeth with a pair of pliers. The teeth are 5 mm deep each. The tricky part is to make a closed ring from the strip. You do it with a solder (your kid can hold the strip while you solder it, let him, or her learn). After the ring is closed put it over the cover and play a little with a pointed pliers until it looks even. Then fil all cavities with clay. Because the teeth are big the tolerances do not matter so much, anyway the product doesn't have to pass Boeing's inspection and it will cost you a fraction of their flap gears. I drilled the 6 mm center holes after casting the gears, but I guess the holes can be part of the mold on the first place.

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Oh man, this is just awesome :-)Nothing to be ashamed of in the cucumber can. It's more of a shame if you spend money on something you can get far cheaper with a bit of a clever thinking.I was also thinking about using polyurethane for casting knobs etc. Korry has all the dimensions of their knobs on their website, so it would be pretty interesting to cut and carve one knob from wood or whatever and cast a mold, then make a bunch from urethane.But yeah, this is pretty ideal for stuff like throttle handles etc. as well.. did not think of that, thanks for the idea.Do you know if it is possoble to mix dyes into the urethane to colorize it? Some titanium dioxide could make nice "boeing" white handles I guess, if the chemical process does not get disturbed.My friend used plain, old fashioned ink to make epoxy resin black, so maybe it might work.Tuomas

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Guest MikePowell

It is indeed possible to add color to plastic casting compounds. Tap Plastics sells the resins and dyes on the west coast of the US. Probably not real convenient to you, but their web site www.tapplastics.com does have a little information on the materials and their use. I would not be surprised to find that the same colorants used with acrylic house paints would work with casting resins.Mikewww.mikesflightdeck.com

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Hehehe, so I went and bought Polyester resin stuff (that thing has the most evil odor you can think of btw :-P - better have GOOD ventilation.. )I did some test castings of throttle levers. Basically flat aluminium with a hole on the end, where I put a bolt and a nut and two more nuts that hold a washer in between them in the middle of the bolt - just some odd shaped stuff for the resin to stick to and to add strength.So for a first test I think this turned out pretty promising!http://tigert.gimp.org/vatsim/cockpit-stuf...-throttle1.jpeghttp://tigert.gimp.org/vatsim/cockpit-stuf...-throttle3.jpeghttp://tigert.gimp.org/vatsim/cockpit-stuf...-throttle5.jpegInteresting stuff if you ignore the smell :-)Yea, that is cough medicin measurement cup I cast the "handles" with :-) My friend has used black ink from ballpoint pens to colorize the polyester black, need to try that for the "production run" :-)Tuomas

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Hey TuomasThat looks really promising! :-jumpyGot to remember this for my production stage. Any ideas on using clay for more oddly shaped casting?I guess your friend mixed the ink into the polyester right?TGIF

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Guest seev_39

Hi Tuomas,I forgot to tell you it stinks, it also needs latex gloves while handling, at least that;s what the lady who sold me the materials say.When you prepare the molds from the artifical clay you have to insert some kind of scafoldings (wood or something) in the mold, because for several days the clay is too soft for handling, especially if the pieces are big. You work on one side of your handle, or knob, and then hups!!! the other side gets out of shape. I some time wonder how kids manage to work with this clay or other clays. That isn't a work for old trembling guys.Have fun Seev

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>I guess your friend mixed the ink into the polyester right?>>TGIFYeah, he mixed the ink into the polyester stuff.>I forgot to tell you it stinks, it also needs latex gloves >while handling, at least that;s what the lady who sold me >the materials say. Yeah. One of the worst chemicals you can get without a buying permit I guess :-)>When you prepare the molds from the artifical clay you have >to insert some kind of scafoldings (wood or something) in >the mold, because for several days the clay is too soft for >handling, especially if the pieces are big. You work on one >side of your handle, or knob, and then hups!!! the other >side gets out of shape. I some time wonder how kids manage >to work with this clay or other clays. That isn't a work for >old trembling guys. So you make a "positive" object with clay and then use casting rubber to cast a mold from it? I have never seen/tried that rubber stuff, but I guess it would be fun to play with. Tuomas

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Guest seev_39

>So you make a "positive" object with clay and then use >casting rubber to cast a mold from it? I have never >seen/tried that rubber stuff, but I guess it would be fun to >play with. Hi Tuomas and Tigert,I Think I used a wrong word in my first explenation probably because of a language barrier, sorry for that. What I meant is the following;First you make a clay model (not a mold - the term I used). Then you cast artifical rubber on it, and after it dries you take the clay model out (through a cut you make) and cast polyester or any other poly resin into the cavity. Again, after it hardens, you take it out and then you have your new piece.The rubber I use is Rhone-Poulenk RTV-2 which dries in about 24-48 hours. The hard polyurethan is the same one used also in the boat repair business, I have no idae who is the producer.I came to the idea after reading an article on "lost wax" casting, which as old as civilization itself.Attached are 2 pictures of the rudder knob I use on my desktop cockpit (too lazy to use my feet for a couple of hours).Seev

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Guest GeorgeDorkofikis

You have small parts to make, or you don't want to use polyester and want to use plastic?Do you do plastic modelism?.. No? Well you should start!...Use the remaining plastic!How? Heat them and melt them. Do NOT heat them too much. You want to melt them, not put them on fire. Use a pot with boiling water and another pot (metal or glass) with the plastic inside. Steer them slightly and make sure you use the same kind of plastic everytime.Then poor the melted plastic into the mold and allow it to dry...Just crossed my mind!.. Used to do that for broken parts in plastic modelism!!!!Cheers,George DorkofikisAthens, Greece

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>Hi Tuomas and Tigert, Heh, I'm only one person :-)>I Think I used a wrong word in my first explenation probably >because of a language barrier, sorry for that. What I meant >is the following; >First you make a clay model (not a mold - the term I used). >Then you cast artifical rubber on it, and after it dries you >take the clay model out (through a cut you make) and cast >polyester or any other poly resin into the cavity. Again, >after it hardens, you take it out and then you have your new >piece. >>The rubber I use is Rhone-Poulenk RTV-2 which dries in about >24-48 hours. The hard polyurethan is the same one used also >in the boat repair business, I have no idae who is the >producer. Oh, then I understood correctly. I need to try that rubber thing, just need to find a place that sells it. I guess hobby shops or such might be a good starting point. Though "cheap" and "hobby store" usually dont mix too well..>Attached are 2 pictures of the rudder knob I use on my >desktop cockpit (too lazy to use my feet for a couple of >hours). Hmm, did not see any images though..?Tuomas

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