Originally posted by Airguardian
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Official Freewing JAS 39 Gripen 80mm EDF Jet
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Was flying this morning with a friend who brought his Gripen. Up until today, he has really disliked the plane and was on the verge of selling it. I've always liked my Gripen and I think it was partially due to the HobbyEagle gyro on it that made it fly so locked in and solid. His had always been a wiggly woggly handful even on very low rates and moderate expo. It was always a bit out of control for him, so I suggested a simple gyro to tame it down a bit. BTW, his has no VT and mine does. This morning, he did a couple of test flights starting with low gain on the gyro and his first flight, he was encouraged by how much more controlled it was. Before the second flight, I suggested he turn up the gain just a little more and surprise! --------- His next flight was solid as a rock. He started to really like the plane and after a couple more flights, he's decided it's his favorite delta and he won't be selling it. It takes off smoothly and it lands near perfectly every time. Banking no longer rocks back and forth, rolls are precise and crisp. No more dancing at slow, high alpha.
(His gyro only affects the elevons and rudder, as does mine.)
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McDaniel,
As Evan D may be implying, you may want to consider adding the Thrust Vectoring (TV) unit. Although TV adds cost, a bit more complexity, use of additional receiver/transmitter channels, and weight to the model (all of which can be valid reasons why someone may not want to add thrust vectoring), we now know in this instance that the added weight of the TV install has potential benefits. Some benefits would be related to fixing what you’re experiencing now as it can help achieve the balance of the model more easily if a larger/heavier capacity LiPo is used (compared to an average 4000mah 6S) and provide the ability to use a more rearward CG if preferred (to what degree of either depends on the specific battery and any other components used). Then, the added maneuverability to the model with TV just be mentioned as well as that’s one of the primary selling factors of it. The TV unit doesn’t need to be active in the sense of moving (although it does still need to be powered and programmed properly to ensure the TV servos remain centered during flight) until you feel ready and confident to fly it with it active. I do not know your RC flying experience, so only you know if you’re ready for it.
I preferred to spend the extra money on the TV unit to add the many functional benefits to the aircraft rather than simply adding ballast to it, and a matter of fact I did.
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Originally posted by xviper View PostWas flying this morning with a friend who brought his Gripen. Up until today, he has really disliked the plane and was on the verge of selling it. I've always liked my Gripen and I think it was partially due to the HobbyEagle gyro on it that made it fly so locked in and solid. His had always been a wiggly woggly handful even on very low rates and moderate expo. It was always a bit out of control for him, so I suggested a simple gyro to tame it down a bit. BTW, his has no VT and mine does. This morning, he did a couple of test flights starting with low gain on the gyro and his first flight, he was encouraged by how much more controlled it was. Before the second flight, I suggested he turn up the gain just a little more and surprise! --------- His next flight was solid as a rock. He started to really like the plane and after a couple more flights, he's decided it's his favorite delta and he won't be selling it. It takes off smoothly and it lands near perfectly every time. Banking no longer rocks back and forth, rolls are precise and crisp. No more dancing at slow, high alpha.
(His gyro only affects the elevons and rudder, as does mine.)
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Thank you guy's for the idea's, as of right now I don't consider the TV unit, I am not into crazy flying so I will start with the wheigt. I fly with Jeti Assist receiver which are performing just absolutely perfect, I even have one in the Funjet 2 Ultra, it flys like on rails even in strong wind gusting conditions...a joy to fly.
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Originally posted by McDaniel View PostThank you guy's for the idea's, as of right now I don't consider the TV unit, I am not into crazy flying so I will start with the wheigt. I fly with Jeti Assist receiver which are performing just absolutely perfect, I even have one in the Funjet 2 Ultra, it flys like on rails even in strong wind gusting conditions...a joy to fly.
Again if you have access to a 3D printer, my heavy nozzle is a more elegant way to fix the CG than sticking weights to the underside.
The Gripen needs weight in the tail to achieve an acceptable CG position. This nozzle has accommodation for up to 60g of small lead weights, in addition to weighing over 60 grams itself. Print wide-side down, with supports. You will need to peel off the plastic outer of the stock nozzle, and trim back the foam to leave a stub 13mm long to which you glue the new nozzle. I suggest taping the join on the inside to ensure smooth airflow,
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So I finally maidened my 90mm Gripen yesterday. A lot more fine-tuning to do, but so far it is the "larger Mirage 2000" that I wanted! From takeoff straight to vertical while accelerating upwards. Flies very nice and slow flight high alpha flight envelope still to be unlocked at lower altitude with more throws added. CG is moving aft, not done with that yet. My configuration is as follows:
FMS 90mm PRO 8S 12blade inrunner
120A ESC
CNHL Black 4S 65C 4000mah x 2
Thrust tube widened to 90% FSA for static thrust. (I think it was that, time has gone by...)
Extra cheater intakes on top and the lower one opened up at the rear.
Centerburner from RC-castle.
Hobby-eagle gyro on canards, will move that to elevons.
Flying weight 3770g, probably 3800-3830g when CG in correct position.
Flight time 3.30-4min.
Couldn't be happier!
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I've just set up my Gripen with the Vectoring Unit and Canards on a FRSKY X20S with the new Ethos operating system and 10 Channel Rx. I'm reluctant to test fly it as Ethos doesn't allow me to disable the Trim on my mixes so the Canards and Vectoring unit follow whatever trims I'm applying via the Tx trims which is not recommended . Could I ask if the Gripen can be flown on Elevons alone, I can then apply whatever Trims are required on the pushrods to center the Tx elevon trims before attempting flight with Canards and Vectoring? I've read through the Gripen posts and it's suggested for normal flight the leading edge of the canards should be set approx 5mm down from neutral, have I understood this correctly?
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