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Official Freewing JAS 39 Gripen 80mm EDF Jet

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  • Having seen Harold's videos, I'm thinking I may forget the VT nozzle for this plane. The plane appears to be able to do stuff that one would have previously thought it could only do with VT. In its stock form, the Grip won't hover anyway, so it may be a pointless add-on. (The VT nozzles may serve a more valuable purpose with the big MiG, though.)

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    • Originally posted by kallend View Post

      I plan to modify it myself.

      I already did overlay nozzles for the Eurofighter TV. Been up on Thingiverse for a long time.
      Yeah, the nozzles definitely need some love. The foam finish in the kit certainly doesn't look too impressive.
      Freewing A-10 turbine conversion: http://fb.me/FreewingA10TurbineConversion

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      • Good point. I'm planning on buying the TVs and if and when my spot gluing of the rear section comes loose installing it. The only hesitation is if the outlet is more inefficient in size and shape than the stock one, that is with the nozzle straight aft as It'll be less efficient with the nozzle deflected. I figure there won't be a weight penalty as I'll remove the lead I added and it should be the same weight more or less.


        Originally posted by xviper View Post
        Having seen Harold's videos, I'm thinking I may forget the VT nozzle for this plane. The plane appears to be able to do stuff that one would have previously thought it could only do with VT. In its stock form, the Grip won't hover anyway, so it may be a pointless add-on. (The VT nozzles may serve a more valuable purpose with the big MiG, though.)

        Comment


        • 4 more flights with smoke on the swedish queen, videos coming... soon enough ;)

          I seriously wonder what went wrong at the factory... the jet was supposed to look like this:

          Click image for larger version  Name:	FWJAS39P1-500x390.jpg Views:	8 Size:	25.0 KB ID:	290882
          Instead we got jets that we can't barely tell decal apart from fuselage grey... :'(

          Originally posted by kallend View Post
          In your experience, how should the gyro pitch gains be apportioned between the elevons and the canards?
          I'd say set canards' gain as high as the gyro will take without oscillations, and then add some more on the elevons if you feel like it.

          Canards tolerate being very sensitive as being close to CG they don't make as much pitching moment.
          Also the stock actuation system quite limits their range and speed so you can abuse gain on them.

          Ultimately I'd decide on what looks most scale for me. But I can't tell yet because I still need to get my CG aft to get proper scale results.

          Too much gain could make the plane 'snap' too hard when finalizing maneuvers and overshooting so at that point I'd probably back off a bit.

          It also depends on how much I shift CG aft. Usually the more 'tail-heavier' the higher gain you want to keep the plane in check.

          Originally posted by HaroldAnderson View Post
          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...
          You know... it happens!
          Not sure gear down is best option in case it does flop... besides ripping gear off it can also cause the jet to bounce and that has potential for more damage.
          Glad to hear it wasn't bad anyway :)

          Wish Freewing/Motion made a reissue of the LG struts with improved rigidity and getting rid of the unnecessary holes. It's quite an annoying aspect of this jet :'(

          ​​​​​​​
          Originally posted by xviper View Post
          Having seen Harold's videos, I'm thinking I may forget the VT nozzle for this plane. The plane appears to be able to do stuff that one would have previously thought it could only do with VT. In its stock form, the Grip won't hover anyway, so it may be a pointless add-on. (The VT nozzles may serve a more valuable purpose with the big MiG, though.)
          Disagree. After 38 flights with the Gripen I find the jet pretty lacking in control authority when AoA gets too high and speed drops (hence my recent crash shown in the previous video ensued), and clearly Harold agrees as he's had two more just like that. The jet has superb low-speed high-alpha handling but it has a limit, after which TV would provide the authority that current aerodynamic controls can't provide. Of course, TV will reduce Gripen performance in speed and thrust, so if you value that more, then don't install it. But if you think installing the nozzle doesn't add any sort of value, you are indeed not flying the jet to its limits.

          Comment


          • Originally posted by Evan D View Post
            I figure there won't be a weight penalty as I'll remove the lead I added and it should be the same weight more or less.
            That may be the only remaining reason for me to get the nozzle - extra weight on the tail end without having to add lead. On the other hand, lead weight may be more advantageous if the nozzle is less efficient at shoving thrust out the back.

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            • Has anyone planned on extending the elevons inboard?

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              • I thought about it but got discouraged by the fact that it is in the way of one of the wing's attachment points with screw.
                If implementing full-span elevons like the fullscale jet, you'd need to 'disable' that joint, move it forward or something.

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                • Originally posted by TangoVector View Post
                  Has anyone planned on extending the elevons inboard?
                  Yes, I've considered it but abandoned the idea for the reasons Airguardian mentioned. I'd want to use the inboard sections as flaps and the dimensions of the existing surfaces would make it a lot of work- doable but...
                  Tom

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                  • Originally posted by Airguardian View Post
                    4 more flights with smoke on the swedish queen, videos coming... soon enough ;)

                    I seriously wonder what went wrong at the factory... the jet was supposed to look like this:

                    Click image for larger version Name:	FWJAS39P1-500x390.jpg Views:	8 Size:	25.0 KB ID:	290882
                    Instead we got jets that we can't barely tell decal apart from fuselage grey... :'(
                    Oh wow!! If mine look liked that I wouldn't be considering painting it.... I guess they got their greys mixed up on the waterslide decals.

                    Comment


                    • Originally posted by Airguardian View Post

                      I find the jet pretty lacking in control authority when AoA gets too high and speed drops (hence my recent crash shown in the previous video ensued) The jet has superb low-speed high-alpha handling but it has a limit, after which TV would provide the authority that current aerodynamic controls can't provide. But if you think installing the nozzle doesn't add any sort of value, you are indeed not flying the jet to its limits.
                      ANY aircraft will be lacking in control when the AoA gets too high. (hence the wing drop) A single TV nozel won’t change this.

                      Having flown both the TV and standard models, the TV doesn’t provided any measurable amount of deck angle above the stock aircraft in high AOA. It adds too much weight for any improvement in directional thrust.

                      The stock aircraft will comfortably hold the same or higher AOA in STABILIZED flight.

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                      • Originally posted by xviper View Post
                        That may be the only remaining reason for me to get the nozzle - extra weight on the tail end without having to add lead. On the other hand, lead weight may be more advantageous if the nozzle is less efficient at shoving thrust out the back.
                        Yes, quite the conundrum.

                        The jet definitely needs the tail weigh of the TV, but also needs all the thrust it can get and then some. I'd hate to lose any thrust that I can get.

                        I'll likely tack on the TV like the existing nozzle and try them back to back.

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                        • Originally posted by Mizer67 View Post

                          Yes, quite the conundrum.

                          The jet definitely needs the tail weigh of the TV, but also needs all the thrust it can get and then some. I'd hate to lose any thrust that I can get.

                          I'll likely tack on the TV like the existing nozzle and try them back to back.
                          Mind you, I bought the ARF and put the FMS 2100kv inrunner and matching FMS ESC in it, so there's that little extra bit of grunt already. As it sits right now, it balances right at the factory marks with the Gens Ace 5000. I'd like to get it back a few mm more.

                          Comment


                          • Originally posted by xviper View Post
                            Mind you, I bought the ARF and put the FMS 2100kv inrunner and matching FMS ESC in it, so there's that little extra bit of grunt already. As it sits right now, it balances right at the factory marks with the Gens Ace 5000. I'd like to get it back a few mm more.
                            I'm trying out a few setups, but have most of my flights on it with the FMS 2100kv EDF. With 4000's weighing about 600 grams and over 100 grams in the tail, I've got the CG about where I'd like it which is well behind the factory marks.

                            I've got an 8S setup in it now, but think the FMS might be the better compromise of the two so far. I need to try the 1865kv HET motor in mine still.

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                            • Originally posted by Mizer67 View Post
                              With 4000's weighing about 600 grams and over 100 grams in the tail
                              What kind of flight times are you getting with that and on what kind of flying?

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                              • Originally posted by JLambCWU View Post
                                ANY aircraft will be lacking in control when the AoA gets too high. (hence the wing drop)
                                Not to the same extent. A Su-35 for instance still has lots of authority way up to great angles of attack even without accounting for the nozzles, just because the huge tailerons are much more effective at having authority over the jet in such an energy deprived condition.

                                The F-18 on the other hand quickly loses all control, way before Su-35 or Gripen as it loses side grip with the vertical fins. Try it out.

                                Originally posted by JLambCWU View Post
                                A single TV nozel won’t change this.
                                Delusion speaking. Of course it will.
                                A single nozzle providing pitch and yaw control when the jet is stalled will give the pilot command authority whereas without TV the jet just plummets to whatever side and you can't do a thing about it. I'm not saying it's going to hover (that's not happening without serious thrust added in the mix) but it obviously will give you extra control that you are now missing.

                                It seems ludicrous that you argue against this.
                                Sounds like you just want to argue for arguing's sake.


                                Originally posted by JLambCWU View Post
                                Having flown both the TV and standard models, the TV doesn’t provided any measurable amount of deck angle above the stock aircraft in high AOA. It adds too much weight for any improvement in directional thrust.
                                That's just your opinion (which I obviously don't share...).
                                And I'm not talking exclusively about 'deck angle' anyway.

                                Originally posted by JLambCWU View Post
                                The stock aircraft will comfortably hold the same or higher AOA in STABILIZED flight.
                                Mine is stabilized.
                                Being stabilized is not worth a penny when the jet stalls and lacks control authority. TV changes that.

                                Shifting CG back and having a VT nozzle, on the other hand, will help keep stable at higher AoA and keep the jet under control when it would otherwise stall.

                                Notice that basically what happens when the jet 'stalls' is that it starts to skid laterally (once you run out of rudder deflection/authority).
                                Just the yaw component of the VT nozzle would already help there to shift the ass around so that sideslip doesn't diverge as much in such circumstances...
                                Not to say, there's a point where full pitch up is no longer allowing the plane to pitch up (at least with current nose-heavy CG). The nozzle will provide control there too.

                                Saying that this won't happen, that a TV nozzle adds nothing is... I don't know, help me find a word for it.

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                                • Originally posted by xviper View Post
                                  What kind of flight times are you getting with that and on what kind of flying?
                                  About 2:45 of useful throttle with mostly flying about 2/3rds to 3/4ths throttle, with some full throttle climbs thrown in and maybe one pass of low high alpha down the flight line

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                                  • Just got mine and trying to measure ailerons and canards. Question is, the 23mm for high rate on aileron, is that full left aileron stick? Or do you have to hold it full left and down? Because just doing full left aileron alone, at 100% on everything is giving me 15mm, but when I put the stick at bottom left corner it measures to the 23mm.

                                    I hope what I’m trying to say is coming through clearly. Any hell is greatly appreciated!

                                    Comment


                                    • Originally posted by RCJetFanatic89 View Post
                                      Just got mine and trying to measure ailerons and canards. Question is, the 23mm for high rate on aileron, is that full left aileron stick? Or do you have to hold it full left and down? Because just doing full left aileron alone, at 100% on everything is giving me 15mm, but when I put the stick at bottom left corner it measures to the 23mm.

                                      I hope what I’m trying to say is coming through clearly. Any hell is greatly appreciated!
                                      I had this exact question myself when setting mine up. 23mm combined throws (stick in the corners) and roughly 15 for just aileron or elevator is what I used and it worked perfect. I did have to make sure to setup the servo endpoints properly to avoid linkage binding against the wings.

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                                      • Originally posted by RudyD54 View Post

                                        I had this exact question myself when setting mine up. 23mm combined throws (stick in the corners) and roughly 15 for just aileron or elevator is what I used and it worked perfect. I did have to make sure to setup the servo endpoints properly to avoid linkage binding against the wings.

                                        awesome thank you! So is the 35mm on the canards combined with sticks in the corners as well? If it is mines at 50mm when in the corners. Or is that only on the elevons?

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                                        • Originally posted by RCJetFanatic89 View Post


                                          awesome thank you! So is the 35mm on the canards combined with sticks in the corners as well? If it is mines at 50mm when in the corners. Or is that only on the elevons?
                                          Does this imply that you have roll input to the canards?

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