Official Freewing JAS 39 Gripen 80mm EDF Jet

[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.

[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.

[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.

[Airguardian]

Yep, it's been debated earlier. Using only the canards for pitch isn't a really bright idea.
Canards should be used in pitch only, but not the other way round (Canards only in pitch, that is), lol


Well, the plane survived so you can correct that mistake. Canards are there mainly for flow control indeed. And they also make a wonderful job at stabilizing pitch through a gyro on high gain without producing oscillations, so there's that too. ^^

[SgtRay]

My pen and paper have been a bit vexed by me lately. It seems I've been ignoring them. So I'm gonna merge writing and flying. Please let me know what you think What can I say a man's got a wright. Lol

[SgtRay]

That was a hell of a flight Airguardian!

[Airguardian]

Thank you very much!
I'll soon be posting more vids... first a compilation of mishaps (three crashes) that I finally found the root cause for, and then the first flights after the last repairs ^^

BTW, that was a cool vid, how did you make all that telemetry screen overlay? Cool stuff! :D

[SgtRay]

BTW, that was a cool vid, how did you make all that telemetry screen overlay? Cool stuff! :D

I just watched this video follow the steps pretty easy after that.

[Airguardian]

Thanks!

[Airguardian]

Inspiration! ^^

[BenOzzy94]

Got my maiden done, after the mirage I was expecting a roller coaster but the rates are ok off the book. She is a kittycat really 😁, Now does anyone know where to get decent 4500 6s batteries in Europe 🤣

[Airguardian]

Congrats!
I get 4S HRB 4200mAh 60C packs from AliExpress. They ship from the German Warehouse.
Can usually get a couple for 100€, or, if you wait for coupons and offers (Black Friday is round the corner), can easily get them for much lower. Like 33€ each 4S pack or so.

May try and fetch you a link later.

[BenOzzy94]

Congrats!
I get 4S HRB 4200mAh 60C packs from AliExpress. They ship from the German Warehouse.
Can usually get a couple for 100€, or, if you wait for coupons and offers (Black Friday is round the corner), can easily get them for much lower. Like 33€ each 4S pack or so.

May try and fetch you a link later.

Thanks buddy, I must admit I do enjoy your videos of the gripen. Can you remember what power system you're using? I know it's 8s and I'd like to stay 6s for cg reasons but I think I might have to go 8s for acceleration reasons

[Airguardian]

Hey, Thanks Ben!

I was running the Jetfan 8S with a HET 1865kv motor (it's a combo you can find out there) with a Freewing 150A 8S ESC... but I don't recommend it.
It's way too power hungry. Destroys and slaughters batteries as if they were made of thin tinfoil. Flight times down to 2:00 - 2:30min compared to the usual 4:30min with stock setup.
Of course I get a better thrust and CG with this setup (EDF and ESC are heavier, and I further hacked foam to move EDF 2.5cm aft) but it's a massive pain in terms of flight time.

Wing loading also went up consistently which hurt the flight envelope quite a bit.

Instead, you'd better go for the other Jetfan 8S combo with the lesser kv motor that is not as hardcore as this one... or even better, stick to 6S but use an FMS EDF. You'll get better thrust on about the same flight-time and won't totally cripple flight performance by increasing the wing loading as much. My 2 cents :)

[BenOzzy94]

Thanks Airguardian. I'll have to look around,
I was considering the Schubeler HSD fan and motor combo as apparently that'll provide 3+kg of thrust on 6s but it's a very costly power system. Still if it gives me strong punch out like the mirage it might be worth it.

[TangoVector]

Well, I have to admit it, my 8S 90mm Gripen project has come to an end. To sum it up, it got too heavy. With almost 5kg of thrust, performance is not the issue, but there is no nimbleness in the flying and the TV-system with some play in it doesn't make things better...
So a new fuselage has arrived and everything except ESC and EDF will be moved over to the new model. I will do the same cheater hole installation on the top of the fuse and there will be a FMS edf in it and one or two gyros, other than that, going stock is the plan, unless anyone has some really good mods that should be done?

Still if it gives me strong punch out like the mirage it might be worth it.

Nothing punches out like the Mirage, just get used to disappointment

[Evan D]

So stock and no TV? I have one 8S and with TV and another box stock no TV. I consider both my favorite EDF but I do seem to fly the stock one more. There may be various reasons but I would say less investment in time and money is probably #1, just charge one battery Forum Using 8S batteries that add up to about 850g the repainted TV'ed one is a bit heavier. But the stock one considering no TV's is very aerobatic.

Yeah, the Mirage is a benchmark even stock, even as it originally came with the low powered out runner.

[BenOzzy94]

Well it seems the consensus is lighter weight is better than more thrust. I have found a link to the new X-fly galaxy fan and motor combo which seems to promise a little too much but I might get one and see what it does to the performance of the jet.
Consider it a mini review of sorts to see does the 3.4kg of thrust with a 6S lipo really add up.

[TangoVector]

So stock and no TV?

I thought about it, but since I have gotten my hands on two SU35 ARF I will get my TV-fix from elsewhere

I have found a link to the new X-fly galaxy fan and motor combo which seems to promise a little too much but I might get one and see what it does to the performance of the jet. Consider it a mini review of sorts to see does the 3.4kg of thrust with a 6S lipo really add up.

The XFLY is according to many on par with the FMS and rc-castle also have them matching in thrust. If I wanted more thrust I would get the Wemotec that also delivers 3.4kg but at 22.2V instead of 25V as the XFLY or FMS, but with higher Amps (and price) of course.

What has been said before at least, is that the Gripen is not getting enough air to the edf, so it might be a good idea to open up some cheaters on the top. I used the Freewing 90mm F16 cheater gilles and they fit very nicely, will move them over to the new one. I might also go for the XFLY together with a VGood ESC.

[Airguardian]

I heard from some that tested XFly against FMS and the FMS came on top.
Also heard opposite reviews. I'm more inclined to think the FMS units are performing better, but I don't have data to prove it.