Official Freewing JAS 39 Gripen 80mm EDF Jet

[Airguardian]

New video! :)

On another note, bit of a rookie mistake here... it turns out I have been a bit dumb with my Gripen setup (NO, not regarding the CG!).

This is my first jet running an S8R stabilized receiver and I didn't properly set up the endpoints, so I was getting quite limited rudder/elevon throws.

Now that I have setup the endpoints right on the gyro, that's a lot of extra elevon/rudder authority that I was missing.

Already made three flights (not today's video) and the jet behaves more to my liking. Already achieved 45º sustained and controlled high alpha just 50cm from the ground.
This will further improve when I get CG more aft.

#hype

[ULTIMATETWO]

Awesome job.. congratulations, please could you share your exact center of gravity and control throws..?. congratulations for that graceful flights.. Manolo.

[Airguardian]

Gracias Manolo!

I have just changed my setup for a better one... will do some more fine-tuning and share that 'improved' setup instead! ;)

But overall, I must be aproximately around 132mm CG and 3cm up/down elevon throw, 3,5cm for canards.
Basically I have the maximum mechanical throws that the stock servos will allow and big doses of expo to deal with them (like 60% on pitch and 70% on roll).

Will do a more comprehensive setup write-down soon enough... bare with me! :)

[kallend]

Heavy nozzle for CG adjustment. It has internal pockets for up to 60g of small lead weights.

[Riesroni]

Heavy nozzle for CG adjustment. It has internal pockets for up to 60g of small lead weights.

Hello
do you have a stl??

[MAVFLIGHT75]

Speed brakes would be something I'd enjoy seeing someone attempt. There isn't a lot of space in there, but with a conformal door it *could* be done. If it would help, I could share some images from the CAD of what it looks like under those areas.

a see thru image would be nice

[kallend]

Hello
do you have a stl??

Yes I do. Do a search on Thingiverse.

[KevinMar]

Hello
do you have a stl??

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

[Mizer67]

Here is the graph showing the Amp draw of that flight.

Thank you. I'd never seen peak voltage for the Wemo, just 22.2V. Glad to see I can use a 120A ESC with that fan as I have a couple of those that are good for 8S.

[Skosh25]

Did maiden + 3 more flights today. Super nose heavy on 5000s as already stated. Make sure you check your grub screws on the gear! One came loose on landing rollout causing quite an interesting ground loop. Fixed with some locktite. I really wish those would have locktite on them from the factory.

She sure is pretty!

[Airguardian]

Yep, had problems with not-loctited screws myself.

[fredmdbud]

Single-gyro scheme for elevons & canards - does it make sense?

Mine's expected to arrive Thursday.

[radfordc]

I flew mine four flights yesterday...wow I really like this one. CG at 135mm, gyro on elevons only. Canards used for pitch only. Roaring Top 4400 70C battery moved 20mm aft by removing foam from the fuselage. 56g lead in tail.

https://youtu.be/ToEm5vohYbw

[HaroldAnderson]

Heavy nozzle for CG adjustment. It has internal pockets for up to 60g of small lead weights.

Perfect! I've been drilling holes in the foam in the tail and gluing in lead but it is very slow. Thanks.

[HaroldAnderson]

New video! :)

On another note, bit of a rookie mistake here... it turns out I have been a bit dumb with my Gripen setup (NO, not regarding the CG!).

This is my first jet running an S8R stabilized receiver and I didn't properly set up the endpoints, so I was getting quite limited rudder/elevon throws.

Now that I have setup the endpoints right on the gyro, that's a lot of extra elevon/rudder authority that I was missing.

Already made three flights (not today's video) and the jet behaves more to my liking. Already achieved 45º sustained and controlled high alpha just 50cm from the ground.
This will further improve when I get CG more aft.

#hype

I've done the same thing on the S8R but I tweaked linkages for more throw. After calibration I had to go back and move all the linkages back to where they were...

I also unwisely flew a plane before the gyro was set up thinking I had it disabled and I would set it up when I had time. The servo reversing on my gyro control was wrong and the servos didn't twitch at all for some reason. So I thought I was good.... Wrong! This made for a very stressful maiden flight. Lasted all of 15 seconds before it was down, luckily with minimal damage. The rudder and elevator gyro throws were reversed. The entire flight looked like a 50 foot sine wave with crazy rudder action thrown in.

[Petronio]

I flew mine four flights yesterday...wow I really like this one. CG at 135mm, gyro on elevons only. Canards used for pitch only. Roaring Top 4400 70C battery moved 20mm aft by removing foam from the fuselage. 56g lead in tail.

https://youtu.be/ToEm5vohYbw

Nice mate! Thats where I have left the CG too...might copy the carving technique to reduce ballast aft 😉👌

[Airguardian]

I've done the same thing on the S8R but I tweaked linkages for more throw. After calibration I had to go back and move all the linkages back to where they were...

I also unwisely flew a plane before the gyro was set up thinking I had it disabled and I would set it up when I had time. The servo reversing on my gyro control was wrong and the servos didn't twitch at all for some reason. So I thought I was good.... Wrong! This made for a very stressful maiden flight. Lasted all of 15 seconds before it was down, luckily with minimal damage. The rudder and elevator gyro throws were reversed. The entire flight looked like a 50 foot sine wave with crazy rudder action thrown in.

Ouch... scary.
I also changed the linkage to get more control surface travel despite manual recommendations. Used furthermost hole both on servo arm and horn on the elevons.
Will eventually replace those servos to be on the safe side I guess...

Same flights as last video, but raw (no music/slowmo):

Video starts with the tip-over from what was going to be my 3rd flight the day I maidened.
Notice of of the main gear struts is pivoting loose, and it flies off when the jet flips over.
This was causing the issue, worsened by badly aligned nose-wheel and cross-tailwind.
Do locktite your grub screws before maiden!

Here are a few pics from today's high alpha... :)

[James]

Single-gyro scheme for elevons & canards - does it make sense?

Mine's expected to arrive Thursday.

Hey Fred, which Gyro are you going to use? I used a blue Eagle AL-3 in the delta setup and it doesn't control the canards even with the mix. Are you going to try to Y-Lead opposite Elevon to Canard?

I have thought about attempting to try the A3 Super 3 as with that one you can have 2 aileron and 2 elevator ports. That might work, but my brain is confused trying to think about it at the moment

[janmb]

Hey Fred, which Gyro are you going to use? I used a blue Eagle AL-3 in the delta setup and it doesn't control the canards even with the mix. Are you going to try to Y-Lead opposite Elevon to Canard?

I have thought about attempting to try the A3 Super 3 as with that one you can have 2 aileron and 2 elevator ports. That might work, but my brain is confused trying to think about it at the moment

I know Frode tried with the black hobby eagle, but had trouble getting all the mixes to work correctly from both the sticks and the gyro compensation. Pretty sure it's doable, but not quite sure what he did and didn't try.

Any news on VT ETA?

[Anders Boström]

Found a major design mistake on Gripen.😅