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Official Freewing JAS 39 Gripen 80mm EDF Jet

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  • Originally posted by xviper View Post
    Not sure how that would work. You could try it, but if you separate the channels on the A3L, now you've got one acting as elevator and the other as aileron (if the A3L is set as "normal wing"). You can't set the A3L as "elevon" for obvious reasons. Then comes the mixing in the TX if you use two open ports on the RX and tell them both to act as elevators, BUT, how does the A3L decipher two elevator signals when you've got them plugged into two different inputs and outputs (1 ELE and 1 AIL for each)?
    I suspect you could set it up as "elevon" with the roll gains set to zero so it only stabilizes pitch. haven't tried it (yet).

    Comment


    • Now that's an interesting idea!

      Would solve the problem of needing to invert a servo direction.

      Comment


      • As I tested various options on this gripen, there is no need for a gyro. However to verify a gyros flying envelope i tried a gyro in the Gripen and of last weekend this was the only canard/Delta jet I've owned and temporarily flying with a Installed hobbyeagle A3 gyro. I few it 10 times and What i found is that there’s zero need to reverse any servos and defiantly zero need for two gyros to make this jet a gyro Assisted jet. I also have the ability yo remove aileron controls to the canards at the flick of a switch. I will make a video of my transmitter settings and of how I set up the jet after work today to help with some of the confusion ive seen here.

        Comment


        • Originally posted by 4923crew View Post
          As I tested various options on this gripen, there is no need for a gyro.
          I've yet to find a R/C plane that NEEDED a gyro. Almost all fly better and smoother, especially in gusty winds, with a gyro.

          Comment


          • Originally posted by Airguardian View Post
            Now that's an interesting idea!

            Would solve the problem of needing to invert a servo direction.

            Tested it on the bench with an A3Pro. It works. Needs a bit of fiddling to get everything moving in the right direction. It does solve the "invert servo" problem.

            Comment


            • Originally posted by kallend View Post
              I've yet to find a R/C plane that NEEDED a gyro. Almost all fly better and smoother, especially in gusty winds, with a gyro.
              This!

              A little bit of me dies whenever I read someone talking about whether or not a model NEEDS a gyro.

              Your car doesn't NEED power steering or cruise control either, but it is damn nice to have anyway. It is virtually never about need.

              Freewing A-10 turbine conversion: http://fb.me/FreewingA10TurbineConversion

              Comment


              • Originally posted by janmb View Post

                This!

                A little bit of me dies whenever I read someone talking about whether or not a model NEEDS a gyro.

                Your car doesn't NEED power steering or cruise control either, but it is damn nice to have anyway. It is virtually never about need.
                Sometimes I really feel like I *need* a gyro but that's only when I decide to fly on a questionable day and the wind is blowing 12 mph gusting to 20 mph. We don't get too many low wind days of under in Oklahoma so almost every plane I own has a gyro. On those calm days the Gripen is super smooth without gyro on, at least it feels that way to me.

                Comment


                • Originally posted by kallend View Post


                  Tested it on the bench with an A3Pro. It works. Needs a bit of fiddling to get everything moving in the right direction. It does solve the "invert servo" problem.
                  Follow up with more details.

                  This is how I have been flying it.

                  AR8360T receiver set up for elevons with AS3X on the elevons. Pitch input also sent to channels 6 and 7 which I have previously used for unstabilized canards with 7 reversed to get both canards moving in same direction.

                  Adding gyro to the canards for pitch only:

                  I used the A3Pro because it allows the gains of the three axes to be set independently. (Can't do this with the A3L)

                  Gyro settings:

                  Normal mode, elevon/flying wing, orientation flat upright. Set aileron gain to zero, elevator to something non zero, rudder gain irrelevant.

                  Pitch output from receiver (Ch6) to gyro elevator input. Nothing to rudder. *Temporary* 1.5mS (neutral) input to aileron input (not sure if needed but didn't hurt) **

                  Gyro "Aileron" and "elevator" outputs to left and right canards. "Rudder" output not connected.

                  A MIRACLE HAPPENED! Everything worked in the correct direction first time. The canards still respond correctly to elevator stick input, move in the correct direction in response to a pitch change, and do not respond at all to roll.

                  ** I don't know whether an input to the "aileron" on the gyro is needed. It flashes a red light if nothing is connected there but everything still seems to work OK. However, leaving a input in an undefined state is not good practice*** and I now have a spare channel (Ch7) so I'm setting that to 1.5mS fixed and leaving it connected.

                  *** A3Pro manual specifically states that the rudder input need not be connected for an elevon/flying wing configuration.

                  Comment


                  • Originally posted by kallend View Post

                    Follow up with more details.

                    This is how I have been flying it.

                    AR8360T receiver set up for elevons with AS3X on the elevons. Pitch input also sent to channels 6 and 7 which I have previously used for unstabilized canards with 7 reversed to get both canards moving in same direction.

                    Adding gyro to the canards for pitch only:

                    I used the A3Pro because it allows the gains of the three axes to be set independently. (Can't do this with the A3L)

                    Gyro settings:

                    Normal mode, elevon/flying wing, orientation flat upright. Set aileron gain to zero, elevator to something non zero, rudder gain irrelevant.

                    Pitch output from receiver (Ch6) to gyro elevator input. Nothing to rudder. *Temporary* 1.5mS (neutral) input to aileron input (not sure if needed but didn't hurt) **

                    Gyro "Aileron" and "elevator" outputs to left and right canards. "Rudder" output not connected.

                    A MIRACLE HAPPENED! Everything worked in the correct direction first time. The canards still respond correctly to elevator stick input, move in the correct direction in response to a pitch change, and do not respond at all to roll.

                    ** I don't know whether an input to the "aileron" on the gyro is needed. It flashes a red light if nothing is connected there but everything still seems to work OK. However, leaving a input in an undefined state is not good practice*** and I now have a spare channel (Ch7) so I'm setting that to 1.5mS fixed and leaving it connected.

                    *** A3Pro manual specifically states that the rudder input need not be connected for an elevon/flying wing configuration.
                    I've gotten to sort of the same conclusion, I am running the AR8360T and have my elevon, rudder set with gyro. Ran a Y to my canards into my A3pro, then to my open aux 7 on AR8360T and ran Mod wire to Aux 8 port. Im getting a slow flashing red light. But my gyro direction works perfect on my canards and normal stick input for canard movement to match my elevons. However I have not figured out how to get my mod channel to work so I can switch gyro on and off. But if I use the pots on the gyro itself I can turn off and slowly turn up gyro gain and seems to work fine. Although have not flow yet (Looks great on work bench). I am still playing with it to see if I dare fly it.

                    I may resort back to just having one gyro AR8360T and leaving my canards un stabilized.

                    Comment


                    • Flying with smoke is terribly addicting.

                      You have been warned!



                      Comment


                      • Originally posted by 4923crew View Post
                        As I tested various options on this gripen, there is no need for a gyro.
                        No one said gyros were 'needed' as such, now, did any?

                        That said, if you want to make the best out of it, it is not a bad idea. The reasons have been covered quite in detail already.

                        Originally posted by HaroldAnderson View Post
                        On those calm days the Gripen is super smooth without gyro on, at least it feels that way to me.
                        Gyros helping with wind gusts (for me) is a nice second derivative of having them installed but not the main reason I do install them to begin with so... ;)


                        Comment


                        • VT just showed up at RCC:
                          https://www.rc-castle.com/index.php?...roduct_id=8964
                          Shouldn’t be long now before Motion gets them in.

                          Comment


                          • I decided to go ahead with the LE flap modification I've been considering and got a good start on one wing, cutting out the shape and installing hinges, the servo etc. Nothing is finalized (glued) and it's very much a WIP but looking pretty good so far, I think. The LE drops about 25 degrees right now, which doesn't look like much, but as it's such a large surface span-wise, and on the front of the wing, I'm thinking it may be enough travel, but of course don't know. At the moment I'm trying to figure out a good way to cover the gap on the underside of the hinge line when the flap isn't deployed. Comments and ideas are more than welcome.
                            Christmas vacation started today so I'll be able to get some quality time in the aerospace facility uninterrupted by work.
                            Tom
                            Attached Files

                            Comment


                            • Originally posted by xviper View Post
                              VT just showed up at RCC:
                              https://www.rc-castle.com/index.php?...roduct_id=8964
                              Shouldn’t be long now before Motion gets them in.
                              I don't like the job they did on the nozzle. It looks pretty cheesy.

                              Comment


                              • Originally posted by Airguardian View Post

                                No one said gyros were 'needed' as such, now, did any?

                                That said, if you want to make the best out of it, it is not a bad idea. The reasons have been covered quite in detail already.



                                Gyros helping with wind gusts (for me) is a nice second derivative of having them installed but not the main reason I do install them to begin with so... ;)

                                In your experience, how should the gyro pitch gains be apportioned between the elevons and the canards?

                                Comment


                                • Same picture that's been on Motions site for a long time. Like other TVs the outside of the nozzle is foam that can be easily peeled off and a better looking 3D printed part put there.

                                  On yesterdays pod cast James said again the TVs are next year. I wish they would update the web site with more info and a better arrival date.


                                  Originally posted by kallend View Post

                                  I don't like the job they did on the nozzle. It looks pretty cheesy.

                                  Comment


                                  • Originally posted by kallend View Post

                                    I don't like the job they did on the nozzle. It looks pretty cheesy.
                                    Yes, it looks a lot like my old 90mm F-18E V2 that was made of EPS foam. If I get one I may have to modify your nozzle to fit it.

                                    Comment


                                    • Originally posted by Airguardian View Post
                                      Flying with smoke is terribly addicting.

                                      You have been warned!



                                      That looked more like an unplanned landing than a crash. :-) I've got two of those right wing tip stalls on video I guess I should upload them to YouTube also. Mine were both with gear down. On one I was able to take off again. The other one was in a crosswind and required gluing the left retract back in place and straightening the landing gear where it bent at the notorious 4 hole weak point...

                                      Comment


                                      • Originally posted by HaroldAnderson View Post

                                        Yes, it looks a lot like my old 90mm F-18E V2 that was made of EPS foam. If I get one I may have to modify your nozzle to fit it.
                                        I plan to modify it myself.

                                        I already did overlay nozzles for the Eurofighter TV. Been up on Thingiverse for a long time.

                                        Comment


                                        • Originally posted by xviper View Post
                                          VT just showed up at RCC:
                                          https://www.rc-castle.com/index.php?...roduct_id=8964
                                          Shouldn’t be long now before Motion gets them in.
                                          Got mine in the main - will not wait. Currently doing my turbine conversion, so great boon to get it all done at once rather than having to pull it apart again later for VT retrofit.
                                          Freewing A-10 turbine conversion: http://fb.me/FreewingA10TurbineConversion

                                          Comment

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