Reverse thrust mechanism

[Guest]

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

[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

[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

[Guest]

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

[Guest]

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?

[tigert 0]

>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

[Mats_J 2]

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

[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

[Mats_J 2]

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

[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

[Mats_J 2]

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

[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

[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

[Guest]

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

[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