Official Freewing JAS 39 Gripen 80mm EDF Jet

[HockeyMac!]

Before the TV upgrade I had added 130g of ballast in the tail.

I hid it inside the vertical stab, also on the foam right below the rudder, being careful not to protrude into the duct and also inside the nozzle on the aft end.

I would recommend considering moving the EDF unit aft as much as you can. I managed to shift mine 2.5cm and that helped a lot.

How did you move the unit back? Cutting some foam? Thx!

[Airguardian]

Yes I had to cut a bit of foam and also adapt the space aft of the EDF so the duct transition would be more or less smooth.

[McDaniel]

Hey guy's, would this be a bad idea? 🤔🤷🏻♂️

Thank you

[xviper]

Hey guy's, would this be a bad idea? 🤔🤷🏻♂️

Thank you

I don't think it's a "bad" idea. However, the further back you can put the weight, the less weight you'll need.

[Evan D]

Curious, why not get the TV unit?

[xviper]

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.)

[T-CAT]

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.

[Gravythe clown]

The Gripen was my first plane I put a gyro in. I put the S8R in it right from the start. It’s is one of my favorite planes to fly, and lands are a dream. Since then I have bought two mor S8R’s. One for my 90mm F-16 and one to put in my F-14 when I do my planned refurbish.

Gravy

[kallend]

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.)

I have had much the same experience with 4 planes now: FW Gripen, FW F-35 (V3), Dynam Hawker Hunter and ArrowsRC F-15. In each case adding a HobbyEagle transformed the behavior and gave the plane that locked-in feeling. I only use "Normal" mode.

[McDaniel]

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.

[Airguardian]

TV isn't just about 'crazy flying'. It's much more about 'control', whether doing crazy stuff, or just regular flying. ;)

[kallend]

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.

Fair enough, it flies fine without the TV.

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.

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

[TangoVector]

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!

[Evan D]

Congrats! Great report.

[Airguardian]

That sounds awesome!
Kinda reinforces my opinion that this should have been a 90mm bird from the get go ( :

[TangoVector]

Had a fellow pilot film a takeoff from wet grass with climb out with my 90mm Gripen. This was flight six, so lots to learn, but I like it so far

[Daryl]

It seems under powered ;)

[Airguardian]

That 90mm update did pay off! :D

[Steve Balaam]

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?

[Evan D]

I have flown mine with the canard mixing off. I tried canards trimmed down I think 3mm and preferred them aligned with the fuselage. Others like them trimmed down…