Official Freewing JAS 39 Gripen 80mm EDF Jet

[Airguardian]

Damn, so what you are saying is that the Gripen is more hungry than the EF? That is certainly not what I would expect.

It is.
Or, more precisely, the 80mm 8S Jetfan setup (9 blades) with 1865kv motor (installed in the Gripen) is more power-hungry than a 90mm 8S 5-6 blades EDF (either Wemo or RCLander) with a 1600kv HET motor installed in the Euro.

Certainly the JAS ducting is much less 'efficient' (very thin ducts) than that of the Euro, and 90mm EDFs in general work better than smaller diameters in my experience.
Of course, regardless of the ducts, we are comparing 1865kv on 9 blades vs 1600kv on 5-6 blades, so there's probably the big difference.
Still one would hope that a smaller-diameter EDF should compensate for lack of cross section with higher rpms and more or less maintain power but nope.

90mm works best, what can I say?

It'd be interesting to test a 6 blade rotor on the 1865kv motor, but not feeling like doing that ATM.

The EF has a very light wing loading, which means it can cruise around happily at low throttle settings (at least, mine can). Not so with my Gripen.

That contributes but I don't think that's quite it. The 're-maiden' flight where I crashed with the Jetfan installed was mostly cruising around on low throttle. It just draws a hell lot of amps even at mid power settings.

And the jet still takes a lot of time to accelerate compared to others, which again, I'd atribute to the ducting and to the fan being 80mm.

[Mizer67]

The Gripen is the most power hungry EDF I own both on 8S and 6S.

Weight is definitely part of it. Mine also seems to like to fly around with its nose in the air, except at high speed.

[kallend]

Damn, so what you are saying is that the Gripen is more hungry than the EF? That is certainly not what I would expect.

The EF has a very light wing loading, which means it can cruise around happily at low throttle settings (at least, mine can). Not so with my Gripen.

[janmb]

Tested the Jetfan today. The plane still flew fine with CG 24mm aft from factory marks on the wings. The jet clearly had more power but I also noticed that closing the cheater with the net made the gain not as significant as it could be.

The bad news is that I crashed, as I drained the battery in bare 3min of use. I didn't even push the jet hard through the flight as I was testing it, so clearly, the 8S 3Ah packs are kinda limited for this setup, despite being perfectly fine on the Eurofighter running a 90mm fan. Cells came down at 3.2V, my bad.

The good news is that I kinda managed to drop the jet on top of some bushes and the damage was minimal.

:/

Damn, so what you are saying is that the Gripen is more hungry than the EF? That is certainly not what I would expect.

[janmb]

All set for maiden tomorrow :D

[Mtpisgah99]

Thanks for the info and video, what is the all up mass with your setup? I have planned to shoehorn the FMS 90mm that will add 200 grams and an 8S 3300mah combo will weigh as an Admiral 6S/5000. So I'm hoping I will not be too heavy for high alpha stuff. Some weight will be gained after carving out foam and mounting a 3dp thrust tube. Any other things you have learned?

Looking forward to some flight footage if it is available later.

added intake. 15% at end of flight. May be starvation!

[T-CAT]

Hi All. I uploaded a STL file for Freewing JAS 39 Gripen main wheel covers on my Thingiverse page and is now available for download. Hope this helps your modding ventures .

https://www.thingiverse.com/thing:4741718

[russ t]

Originally posted by russ t : Sorry, I can't find the racks you are referring to. Perhaps becoming blind ( which is not good for RC). Please could you post a link or post #. Thanks.
Airguardian replied: #1596 https://www.hobbysquawk.com/forum/rc...273#post296273

Thanks Airguardian. I realize now that Firefox for Android was not showing me the pictures, even if I logged into HobbySquawk. With other browsers ok.
Cheers, Russ.

[Airguardian]

LOL


I, of course, started by checking out racks made by others to get ideas, but I'm fairly confident the output is original enough! ^^

[janmb]

Designed them together with dad. Told him what I wanted, he made a concept, I improved it substantially with a few ideas and then he built it.
Can't complain!

Ripoff! :D

[Airguardian]

New video with red smoke (from before Jetfan upgrade) :)

[Airguardian]

Wow, you take the scale realism to new heights by re-enacting the 1993 Gripen crash at the Stockholm water festival

Lol, wasn't quite the plan!

Sorry, I can't find the racks you are referring to. Perhaps becoming blind ( which is not good for RC). Please could you post a link or post #. Thanks.

#1596
https://www.hobbysquawk.com/forum/rc...273#post296273

[kallend]

Anyone know what rockets/missiles will fit on the Gripen 's wing tip

Did you check Thingiverse? There are several 1:9 scale missiles on there (I have posted Sidewinder and IRIS-T, and someone else posted a Meteor.

https://www.thingiverse.com/thing:4653284

https://www.thingiverse.com/thing:4706132

There are also underwing pylons posted.

https://www.thingiverse.com/thing:4713773

[russ t]

Designed them together with dad. Told him what I wanted, he made a concept, I improved it substantially with a few ideas and then he built it.
Can't complain!

Sorry, I can't find the racks you are referring to. Perhaps becoming blind ( which is not good for RC). Please could you post a link or post #. Thanks.

[xviper]

Anyone know what rockets/missiles will fit on the Gripen 's wing tip

I used the big ones from the MiG29. Painted one red and the other one blue. I think the smaller ones will also fit the slots.

[Tigerman]

Anyone know what rockets/missiles will fit on the Gripen 's wing tip

[TangoVector]

The bad news is that I crashed, as I drained the battery in bare 3min of use. I didn't even push the jet hard through the flight as I was testing it, so clearly, the 8S 3Ah packs are kinda limited for this setup, despite being perfectly fine on the Eurofighter running a 90mm fan. Cells came down at 3.2V, my bad.

The good news is that I kinda managed to drop the jet on top of some bushes and the damage was minimal.

:/

Wow, you take the scale realism to new heights by re-enacting the 1993 Gripen crash at the Stockholm water festival

Good to hear the damage was minimal and looking forward to hear more about your new setup as you get it back in the air.

[TangoVector]

yes, i maiden flight 10x with different batteries 5.5k, 6k, 5k, for 2.5 minutes and 15% @end
its fast and heavy. descent quick, very little glides characteristic, alpha/flare in landing
lost control easily, always powered or need more cruising speed than normal.

Thanks for the info and video, what is the all up mass with your setup? I have planned to shoehorn the FMS 90mm that will add 200 grams and an 8S 3300mah combo will weigh as an Admiral 6S/5000. So I'm hoping I will not be too heavy for high alpha stuff. Some weight will be gained after carving out foam and mounting a 3dp thrust tube. Any other things you have learned?

Looking forward to some flight footage if it is available later.

[Airguardian]

I like your storage racks.

Designed them together with dad. Told him what I wanted, he made a concept, I improved it substantially with a few ideas and then he built it.
Can't complain!

[Airguardian]

Tested the Jetfan today. The plane still flew fine with CG 24mm aft from factory marks on the wings. The jet clearly had more power but I also noticed that closing the cheater with the net made the gain not as significant as it could be.

The bad news is that I crashed, as I drained the battery in bare 3min of use. I didn't even push the jet hard through the flight as I was testing it, so clearly, the 8S 3Ah packs are kinda limited for this setup, despite being perfectly fine on the Eurofighter running a 90mm fan. Cells came down at 3.2V, my bad.

The good news is that I kinda managed to drop the jet on top of some bushes and the damage was minimal.

:/