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Official Freewing 90mm F-104 Starfighter Thread

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  • Thank you. I’ve gotten used to mixing gains with throttle / flaps / etc on Spektrum so prefer to stick with the method I know. I’m sure a lot is possible with the installed F104 gyro as well but I have a spare 8 channel Spektrum at home so it will save me learning curve to just go with that. But will need to order and assemble the plane first! So probably a month or so and I’ll report back.

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    • Sounds like a really good plan.

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      • My Freewing Starfighter.
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        • I recently bought one of these, my first edf. I mainly fly scale jets but the loss of suitable airfields where I live made me sell most of them including my Avonds F-104 which is about 50% bigger than the Freewing and was powered by a 100N jet.

          I have now had 14 flights with this model. I use telemetry on the battery and fly until I have used 70% of its capacity, I typically start to set up the landing circuit at 65% and am landing by 70%. Depending on how much high throttle has been used that gives me flight times from 3:30 to 4:20. Peak current at start is 123 Amps, I find flying at around half throttle stick which is typically 52 Amps to 60 Amps gives a nice speed and the longer flight time.

          Here are my thoughts on the Freewing 90mm F-104 -
          1. I am really enjoying flying it, I was hesitant about having a foamy edf after having a "proper" jet but I am very pleased with it.
          2. Most time when I select gear up or down my Tx warns me of low Rx voltage. The alarm is set for anything below 4.5V and the data logs confirm it is dropping to around 4.4V. Clearly the alleged 8A BEC that comes fitted to the model is not able to meet the demands of the retracts so I will pull it out and replace it.
          3. The anhedral is not enough for scale, it looks a bit wrong but you probably have to know the F-104 quite well to notice something like that, I expect most people will not see anything wrong about it. I suspect it is because more anhedral would not be allowed by the straight wing joiner.
          4. I chose the Admiral 5100 Carbon lipo from MotionRC.eu, with this the model balances exactly on the spot specified in the instructions.
          5. The value for aileron travel given in the instructions, up to 25mm, is very wrong! I have mine at 12mm and the roll rate is still a bit too fast for my liking. Easy to fly it but too fast for scale. God knows what 25mm travel would do!
          6. The built in afterburner light is next to useless. It is recessed in the foam, only visible at certain side angles and not from behind, it is too dim to see most of the time, and is the wrong colour. Apart from that....
          7. I use an Rx with a gyro built in so I removed the gyro that came with the model and the surplus wiring it required. I tried the gyro that comes with the model for the first 4 flights and it seemed to work fine but its drawback is that you cannot adjust the gain by radio, it has to be done by preset pots, which is so last century! I put a GPS telemetry module where the gyro had been so it kept balance.
          8. The undercarriage springs are far too hard with the result that the legs behave as if they are solid wire. I will get around to calculating correct springs and fitting them, in the meantime I have softened the noseleg a little by cutting 2 or 3 coils from the end of the spring. Although that increases the spring rate which is not good, it does reduce its length and thus the full extension force, so that the noseleg spring can actually start to work. A nose spring that is too hard is the cause of a lot of bouncing when models land.
          9. The multi-function board is not in a case, it is out in the open meaning all the component legs and solder joints etc are open to any drops of water, any stray conducting material etc. I think that is very poor so I will need to make a cover or get some pcb varnish to insulate it all.

          So, some things could be improved, especially a BEC that doesn't go low V when I operate the gear, and a multi function board whose electrics are exposed, but overall I am pleased with the model (I have experienced far more problems with models costing many times more!!), I am enjoying flying it and I would not hesitate to replace it or try another Freewing edf.

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          • Interesting post and thank you for your insight especially comparing it to a much more expensive example.

            I don't use telemetry but it does sound like the gear is drawing down the BEC voltage. The gear on this and the F-16 is complicated, maybe trying to reduce the friction/ stiction of the gear? Replacing it sounds very difficult and maybe more expensive than the aircraft itself.

            Yeah anhedral isn't right.

            I fly a 6000 Socokin in mine. I did put the higher power FW 90mm fan in it as mine came with an older, lower power set up.

            Yeah, they also give a low rate 20mm but I'm close to that value. I do like a quicker roll rate than most people.

            AB, yeah not good. Many had paint over spray and not visible at all.

            I'm happy with the stock E51 I've used in both my F-104's, It's just dialing in the correct amount of sensitivity for your own feel. But having it adjustable in flight, mixed to the landing gear switch would be nice. The newer E52 may be a good upgrade if you are not flying a receiver with built in gyro.

            I'm good with the gear springiness...

            I have a large number of these with open boards and have never had an issue... Yet... Good idea to make a cover.

            Please keep us advised of what you do about the gear pulling down the voltage.


            Thanks!​

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            • I have replaced the BEC that comes built in to the model with a high quality brand BEC. That has solved the problem. The BEC that comes in the model claims to be 8 amp, either it is faulty or it is Chinese "optimism". Electric retracts work by detecting the stalled current and shutting off. So by definition the peak current occurred where the retract stopped and not during any part of the motion where they are stiff or sticky but keep moving. For retracts of this size the peak current if all 3 reached stall at the same time, would be no more than 1.5A and probably less. Add in the general current for the radio and lights and it should peak at about 2 - 3 amps for an instant. An allegedly 8A BEC that drops to just over 4V is faulty or is not anywhere near an 8A rating. The BEC was putting out 4,85V and dropping to or below 4.4V. The replacement BEC has an adjustable output so I set it to 5.5V (equivalent to a fully charged Nicad or Nimh) and at worst it loses 0.2V when the retracts stall.

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              • The more common retracts used in the foam planes from various manufacturers have travel limit switches that stop the movement. If the switch isn’t working for some reason there is a timing circuit that turns it off. They don’t turn off by amperage.

                With a light you can look down inside and see the switches on the board. Or take one apart.

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                • Originally posted by HarryC View Post
                  Electric retracts work by detecting the stalled current and shutting off. So by definition the peak current occurred where the retract stopped and not during any part of the motion where they are stiff or sticky but keep moving.
                  Perhaps some do but it's not likely this one does. Read what Evan D said. If you take apart one of these F-104 retracts you'll see the limit switches. I've converted a set of retracts with limit switches to current overload sensing. To do this, the limit switch has to be removed from the equation and the need for a retract controller. You know these types of electric retracts usually by the fact that they have only 2-wire leads instead of the 3-wire leads that Freewing uses for their retracts. I've had planes from the factory that have had both types. I prefer the ones with limit switches but that's just my own experience. Either type can stop mid-cycle if there is excessive resistance in the cycle path.

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