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Official Freewing JAS 39 Gripen 80mm EDF Jet

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  • Originally posted by TangoVector View Post
    I have the Gripen in the box, waiting for TV-unit and my painting-skills to improve since it needs a Swedish livery. I have the Tigermeet M2000 and just love the option to power out of bad judgement at low altitude and I would really like the Gripen to be able to do the same and to accelerate in the vertical.
    There seem to be a lot of knowledge and experience in this thread, so what do you suggest? Is it even possible? If 8S, any specific combos you think are good? Is 90mm an option or is the inlet or outlet area not large enough? Any ideas are welcome, except turbine, I'm not there yet
    The revised 80mm Wemotec Fans fit into the airframe without the need to shave any foam. All you need to do is to reduce the outlet diameter of the nozzle by 2mm for best results (Wemotec recommendation). Look at my video further up in the thread. HET 700-60-1865KV motor, 8s 4500mAh Lipos.
    Another video with this setup has just been posted on YT, look for “mwt- Icarus the 2nd”. I don’t want to steal his video, hence no link....

    Comment


    • Originally posted by Radar-Guy View Post

      That’s what my 8s Wemotec setup delivers and it’s good for about 150-200m in the Gripen. A similar setup in the FW L-39 is good for about 300m vertical climbs.
      Is the 200m maximum height you're referencing for the Gripen taken from a full speed straight and level pass pulled into a fully vertical climb out?

      My Mig-21 on 6S with the FMS 2100kv fan will do about 200m climbs before stalling, so for me that'd be a good reference point.

      Comment


      • Originally posted by Mizer67 View Post

        Is the 200m maximum height you're referencing for the Gripen taken from a full speed straight and level pass pulled into a fully vertical climb out?

        My Mig-21 on 6S with the FMS 2100kv fan will do about 200m climbs before stalling, so for me that'd be a good reference point.
        Yes, it is. I have that FMS fan in my MiG-21 as well, the 8s Gripen gives a more agile feeling IMO.

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        • Somethings not right then. I have a JF with a HET 700-60-1738 that makes 98A and 2766 and I peter out at about 400ft. The other one I have flown has the HET 700-60-1865 making 119A and 3260W and it goes farther than I can see not slowing down.

          When I do climbs I come across at about 2/3 throttle and then go full full throttle just before the pull to vertical.

          Comment


          • Originally posted by Captain Moron View Post
            Been put off the Gripen by the post about it's alleged lack of power.

            Just need someone to reassure me this Gripen is worth buying and not a white elephant
            ​​​
            It's the most fun I've had with my pants on for some time!

            Comment


            • Originally posted by Captain Moron View Post
              Been put off the Gripen by the post about it's alleged lack of power. I just want to fly it scale like I am not that interested in tearing up the sky but if it is underpowered I might give it a miss, which is a shame because I have always like this model. I am not going to buy a model then buy a different motor to put in it. I am sure Alpha knows more then most about what motor wlll suit this model and he has been right on all the other Freewing models I own. Just need someone to reassure me this Gripen is worth buying and not a white elephant
              ​​​
              I love my Gripen. Using a ~4000 pack or less is really the sweet spot on stock setup. If you can handle the shorter flight times it's a great jet.

              Comment


              • Originally posted by Radar-Guy View Post

                Yes, it is. I have that FMS fan in my MiG-21 as well, the 8s Gripen gives a more agile feeling IMO.
                Thanks Radar-Guy. Love fast and agile.

                That Wemo setup looks perfect for me as I hate cutting foam and prefer to do as little modification to the airframe as possible.

                I would be curious what thrust numbers you're seeing installed though if you have any. I agree with Evan D that I'd expect the 1865kv HET w/3300W on the Wemo to give closer to 1:1+ T/W settled.

                Comment


                • 3.2kg thrust with a fish scale with the JF/ HET 1865kv.

                  Comment


                  • Originally posted by Mizer67 View Post

                    Thanks Radar-Guy. Love fast and agile.

                    That Wemo setup looks perfect for me as I hate cutting foam and prefer to do as little modification to the airframe as possible.

                    I would be curious what thrust numbers you're seeing installed though if you have any. I agree with Evan D that I'd expect the 1865kv HET w/3300W on the Wemo to give closer to 1:1+ T/W settled.
                    Wemotec claim 3,75N bench thrust (serious tests at 3,7V). I stopped measuring static thrust with fish or kitchen scales a while ago after seeing too many doubtful results. My Gripen weighs in at about 3,5kg and I’m quite happy with the performance, but there’s no unlimited vertical performance (at least not with 8 deg C outside).

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                    • Understood, all the numbers I’ve posted are ones we’ve taken. With the system installed in the plane on freshly charged everyday batteries.

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                      • Never had a model with cannards before. Is it still possible to install a Hobby Eagle L 3 gyro to the Gripen or do the cannards pose a problem with fitting a gyro like the Hobby Eagle to the Gripen?

                        Comment


                        • Originally posted by Captain Moron View Post
                          Never had a model with cannards before. Is it still possible to install a Hobby Eagle L 3 gyro to the Gripen or do the cannards pose a problem with fitting a gyro like the Hobby Eagle to the Gripen?
                          No problem with the canards in fitting a gyro. I think most have settled on a gyro only on the elevons and rudder.

                          I have an A3 Super 3 on mine. I couldn't get canard stabilization as well as stabilization on the elevons and rudders using just the A3 Super. I tried a few solutions on the canards only, but none I was satisfied with. It flies fine just like a normal delta w/o canards on the gyro.

                          Comment


                          • Originally posted by Captain Moron View Post
                            Never had a model with cannards before. Is it still possible to install a Hobby Eagle L 3 gyro to the Gripen or do the cannards pose a problem with fitting a gyro like the Hobby Eagle to the Gripen?
                            A3L handles deltas just fine. Just use it on the elevons. The canards won't be a problem.

                            (I'm not using it on this Gripen, but I've used it on other deltas with canards.)

                            Comment


                            • More Gripen fun!

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                              • Originally posted by Mizer67 View Post

                                No problem with the canards in fitting a gyro. I think most have settled on a gyro only on the elevons and rudder.

                                I have an A3 Super 3 on mine. I couldn't get canard stabilization as well as stabilization on the elevons and rudders using just the A3 Super. I tried a few solutions on the canards only, but none I was satisfied with. It flies fine just like a normal delta w/o canards on the gyro.
                                Did you try to X-link them to the elevons like Fred and I did?

                                Comment


                                • Bought a Gripen 2 weeks ago. Flies incredible good. Nice topspeed 194kmh slightly downwards. 180kmh level. Good controllable in high alpha. Nice and easy to land. Can do incredible short-field landings , use not to high alpha, but higer sink-rate and flair in the last 2sec.
                                  - the CG is to far forward, wish the battery compartment more backwards.
                                  - The power is ok, but may me to little for thrust vectoring, may be thats why its not available?
                                  Did measure the trust to 2,4kg with a fish weight with a SLS 6s 3500 30c, took of the inspection "lid" under got 2,7kg. As long as it have speed it goes good. Doing som test and plan do modify for more thrust. Realy like this plane, wish I could get this in 12s with high performance.

                                  Very much good info in this tread.

                                  Video doing high speed and hige alpha landing.

                                  Wish i could fly it more, but we hav got 20cm snow..so winter is on its way now.

                                  Comment


                                  • Originally posted by TangoVector View Post
                                    I have the Gripen in the box, waiting for TV-unit and my painting-skills to improve since it needs a Swedish livery. I have the Tigermeet M2000 and just love the option to power out of bad judgement at low altitude and I would really like the Gripen to be able to do the same and to accelerate in the vertical.
                                    There seem to be a lot of knowledge and experience in this thread, so what do you suggest? Is it even possible? If 8S, any specific combos you think are good? Is 90mm an option or is the inlet or outlet area not large enough? Any ideas are welcome, except turbine, I'm not there yet
                                    The Cg might be a problem with the 8s, you should get it in the air, it flys very good. And with the right mods it vill be a incredible plane.
                                    90mm with TV might be the way to go. I did think of putting the fan unit more backwards id doing something like this. You will need more air into the fan.
                                    Got from 2,4kg to 2,7kg thrust took of the box/ lid under the fan.

                                    Comment


                                    • Originally posted by rms View Post

                                      The Cg might be a problem with the 8s, you should get it in the air, it flys very good. And with the right mods it vill be a incredible plane.
                                      90mm with TV might be the way to go. I did think of putting the fan unit more backwards id doing something like this. You will need more air into the fan.
                                      Got from 2,4kg to 2,7kg thrust took of the box/ lid under the fan.
                                      3D printed heavy nozzle can help with the CG. The one I posted can add up to an additional 60 to 120g of weight back there.

                                      https://www.thingiverse.com/thing:4650359

                                      Comment


                                      • Thank you all for more knowledge, this forum is great! After looking at different fan-combos, the HET 1865kv mated with a JF or Wemotec seems to be the most 80mm thrust available at the moment, as you guys already have found out. I'm looking at the FMS 90mm metal 1500kv, wondering how much thrust will be lost in the tight space in the Gripen after it has been shoehorned in there. It claims 4.9kg thrust at 29.6V/108A, equalling 3.2kW. That thrust will not happen with not enough airflow, but if it is capable of giving >4kg thrust, that would be interesting. But a lot depends on the airflow and how smooth surfaces that can be achieved and if it doesn't work, I have a perfect excuse to get myself an F22 ARF...

                                        I know I will like it as it is, but future mods are always being planned. I have the Su35 and the M2000 and have visions of this one being the perfect mix of both. There's a good chance I just get the TV and be happy with that... or maybe not!

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                                        • TangoVector I don’t think that it’s such a good idea to consider the FMS 90mm fan for the Gripen...


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