Official Freewing JAS 39 Gripen 80mm EDF Jet

[kallend]

I flew with pitch on canards only. They are "pretty ineffective".

Why would you do that?

The canards are close to the CG so any pitching moment they exert will be small. On the full size plane the canards are primarily for airflow control, not the primary pitch control.

[JetFun]

I flew with pitch on canards only. They are "pretty ineffective". Really needed to speed up a number of times to actually get them to to what I wanted them to do. Deflection was all up to about 4,5 cm. Long way to start..... So I would not bother using them for roll anyway if you have trouble programming them. Use them for added pitch and you will be just fine. Look at the huge deflections on the MIG-29 or F-22 and Gripen canards are in comparison just tiny. If you try flying with canards only - to see how effective they are - make sure you have a safe setup on another phase.

If you wonder about using roll and pitch on the canards - most transmitters need extensive workarounds as one direction is always wrong. Even when switching servo position on the receiver or reversing the direction. Simply because up and down works the other way around on the canards compared to a normal delta tail. If you have fun programming go for it - otherwise don't bother.

What works fine is a 4-5mm up deflection on the ailerons during landing with no compensation from the canards. Results in a nice high landing alpha and slows down nicely. I flip the switch about 5 -10 meters above ground.

I fly 50 - 60% expo. Always did that on 3d aerobatic aeroplanes.

[Airguardian]

Personally, I tried to get all the deflection I could mechanically on the canards. On the elevons I think I put the linkage one hole more inwards than recommended to gain some extra throws. I then smoothed it all out with expo. I have the servos set to deflect to their maximum. Once I do that, I may slightly limit the throws to avoid asymmetries in throws or to prevent control surfaces binding at the limits.

[xviper]

How many mm are your deflections for the elevator functon in the rear (ailerons) and the canards? Not sure how many mm I should use on the elevators for the pitch function.

Everyone will have their own preference based on their experience and flying style, so it's a bit of a loaded question as is what expo others are using. You should start with what the book says, which also states that elevator travel should be the same as aileron travel. If you have switches that give you 3 rates, use the book values for low and high and dial in either a lower one OR a higher one depending on how you feel about it. Or do what I do to start with ................... dial in a slightly lower rate than the lowest book value and a slightly higher rate than the high book rate and do an average for the middle rate. Go fly it and adjust accordingly. It will also be different if you have the vector nozzle.

[JetFun]

How many mm are your deflections for the elevator functon in the rear (ailerons) and the canards? Not sure how many mm I should use on the elevators for the pitch function.

[Airguardian]

Also got to see the Gripen's daddy... huehuehue!

[Airguardian]

Greetings from Sweden!

Bonus:

[Icarus the 2nd]

Nice demo of an 8S powered Gripen in strong winds, recorded at a German EDF meeting 2 weeks ago.

Enjoy!

[Icarus the 2nd]

If one of you guys need a few unnecessary but cool looking 3d printed extra parts for your Gripen , like for storing or on Display at the field, here a few intake and exhaust covers for your GRIPEN (but keep in mind you need a bit of a 4mm softrubber cord to complete them )...you can find them on thingiverse under JAS39, blue skys

very nice!

[WarbirdFan66]

If one of you guys need a few unnecessary but cool looking 3d printed extra parts for your Gripen , like for storing or on Display at the field, here a few intake and exhaust covers for your GRIPEN (but keep in mind you need a bit of a 4mm softrubber cord to complete them )...you can find them on thingiverse under JAS39, blue skys

[Husafreak]

Haven't visited in a while but another thread got me going so I gotta share. I absolutely love my Gripen now. I'm flying it with an XFLY 80mm 12 blade 2200 Kv fan, 6s 4000 mAh 60c batteries, and Eagle A3-L gyro. I have the canards working pitch only. It is sooo light and the power is good. Nothing I own is better for super tight maneuvering and it just will not stall. With the power I can always blast away from any "situation" without sinking. But yeah, those main gear doors! I take off into a vertical, reduce power and raise the gear while doing a hammerhead stall, works like a charm :)

[Airguardian]

That's because you're a crazy man... 🤣🤣🤣👍

Well, that's entirely possible...

Not working with a decent 8s fan, she accelerates vertically

I'm using an 8S Jetfan with HET 1865kv motor so it's not like I'm lacking power... going straight into vertical and pull gear up while on the climb is my second go-to strategy!


That said, my addition of a mosquito net on the cheater to protect the EDF limits my fan performance and also, despite my attempts at protecting it, the rotor is getting chipped already.

Anyway, I crashed again the Gripen and in the repairs I'm getting rid of the wing spar and spar sleeve so that should improve substantially my thrust output. Weight savings are about 30g.

[Radar-Guy]

I usually go straight from take-off into high alpha to retract the gear at low speeds, then I proceed with the flight. ;)

Not working with a decent 8s fan, she accelerates vertically

[kallend]

I usually go straight from take-off into high alpha to retract the gear at low speeds, then I proceed with the flight. ;)

I go gear up as soon as there's no way to abort to the runway, which is generally immediately after liftoff since our runway is short.

[jasmith41]

I usually go straight from take-off into high alpha to retract the gear at low speeds, then I proceed with the flight. ;)

That's because you're a crazy man... 🤣🤣🤣👍

[Airguardian]

I usually go straight from take-off into high alpha to retract the gear at low speeds, then I proceed with the flight. ;)

[Radar-Guy]

Hello,
I can not find the post now but now O got the same problem as others, the gear door will not be closed when you retrac the landing gear. what is the solution to this? I do not see that something is bent or so.

My Gripen is 8s powered and it always happens when I don‘t retract the landing gear ASAP after take-off, it’s obviously related to higher airspeed. When it happens, reducing the airspeed and cycling the gear helps every time.

[The swede]

Thanks Evan D, I will check that! I didn’t know where to start 😁

[Evan D]

On mine it’s a sign to tighten the set screws holding the strut to the retract.

[The swede]

Hello,
I can not find the post now but now O got the same problem as others, the gear door will not be closed when you retrac the landing gear. what is the solution to this? I do not see that something is bent or so.