Official Freewing JAS 39 Gripen 80mm EDF Jet

[4qr1hu9n7]

Very true. Now you can use the 5000 mah battery without having to add the equivalent in "dead" weight to balance the Gripen.

[xviper]

Very true. Now you can use the 5000 mah battery without having to add the equivalent in "dead" weight to balance the Gripen.

A battery placed in the available space adds to nose weight, not tail weight. The bigger the battery, the more nose heavy it is and the more tail weight you'll need to balance it properly.

[Justwingit]

I see many of you folks over on another fun-filled RC Forum, but I figured I'd post up some viddys over here at Hobby Squawk as well...😁

Here's Justin (JLink125) getting in a good sport flight with the JAS 39 recently down at Rabbit Dry Lake 😎:

As far as I'm concerned, this pretty much RIPS on a single 80mm fan 😲!

[Gravythe clown]

Got 3 more flights in today. One thing I’ve done is my canards have -100 expo and my elavons use +30 expo. This give canards more control faster through the stick movement. I really like how she takes off now and how the assend feels heavy. Did a couple cobras with her today and really like how they looked with this setup.

also tried with timing set in high, did feel a bit more lively. I used a 5200 pack and got 4+ minutes flight with 3.8v at the end

ill keep her.

Gravy

[Mizer67]

My **guess** is that you would see a more noticeable improvement in climb rate than in top speed.

I can't test rate of climb, unfortunately. I could test max altitude, but that's about it.

[JLambCWU]

High Alpha Demo
On the JAS-39 Gripen from Motion RC

The definitive High Alpha demo on the stock 80mm Gripen.

This jet DOES NOT have thrust vectoring, and I’m NOT running a gyro. Powered by the superb 70C 4400mah Roaring Top from RCJETWERX
CG is right on the stock location with no battery bay modifications.

https://youtu.be/HH84CFHjdkk

https://rcjetwerx.com/product/rt-6s-4400-70c/

Get your Gripen here!

https://www.motionrc.com/collections/rc-jets/products/freewing-jas-39-gripen-80mm-edf-jet-pnp

[HaroldAnderson]

High alpha slow flying doing figure eights with the Gripen. I got distracted and let the nose get up too high stalling it but it recovered nicely. Love this plane!! If only my FW F-18 could do this.

https://www.youtube.com/watch?v=H-YYfGXnzAg

[janmb]

Nice high alpha Justin. And even more impressive considering that the setup is pretty far from optimal for that flight.

[DCORSAIR]

High alpha slow flying doing figure eights with the Gripen. I got distracted and let the nose get up too high stalling it but it recovered nicely. Love this plane!! If only my FW F-18 could do this.

https://www.youtube.com/watch?v=H-YYfGXnzAg

Nice flying right there, at least it's a video where you can actually see the jet..!

[4qr1hu9n7]

A battery placed in the available space adds to nose weight, not tail weight. The bigger the battery, the more nose heavy it is and the more tail weight you'll need to balance it properly.

Did you see my heavy nozzle? It's a way of adding tailweight (up to 120g) without affecting the appearance (in fact it probably improves it)
This is what "kallend" said.

[Bajora]

High alpha slow flying doing figure eights with the Gripen. I got distracted and let the nose get up too high stalling it but it recovered nicely. Love this plane!! If only my FW F-18 could do this.

https://www.youtube.com/watch?v=H-YYfGXnzAg

Impressive! Seeing a model that big just "hanging" in mid-air like that all but defies the laws of gravity and physics. Nice flying!

[xviper]

Did you see my heavy nozzle? It's a way of adding tailweight (up to 120g) without affecting the appearance (in fact it probably improves it)
This is what "kallend" said.

Sorry, missed that reference.

[Pogo]

I had some time in the shop this weekend and began the planned modifications. Landing lights were added to the main gear (as the full size has) by bonding aluminum tubing to the struts with KB weld into which the LED's slide. Plastic tubing was used to hide the springs.
The silly nose light was removed and a bulb fitted to a door made from 'glass sheet to sort of replicate the real Gripen. After some trial and error I used pinned hinges and a spring from the Venom nose door to close it and then cut back the existing doors.
The struts and insides of the doors were painted white and the wheels got a bit of detailing, as did the exhaust nozzle with some weathering and a flat coat applied. The inside was covered with aluminum tape to enhance the LED 'afterburner" and the last inch or so painted to simulate a jet pipe. The 'burner is one of Gooniac's (thanks Ray!) and although not installed for the first 2 flights it's in there and working now and I think it's going to look great in flight.
Tom

[JLambCWU]

4th flight LIVE High Alpha/Slow flight demo.

This is my 4th flight on the model that I did LIVE on FB demonstrating the slow flight/High Alpha capabilities of the model at the stock CG location.
I also demonstrate the “flap” function I have set up on my canards using only 6 channels.

With almost 4000 views on FB already, I took the time to upload it to YouTube to be able to share it. UNFORTUNATELY this means there is a pretty low quality/frame rate off the live feed recording.

This is rocking the 4400mah 70C Roaring Top from RCJetWerx that allow for balancing on the factory CG marks on the jet, while also giving great power into the vertical out of High Alpha passes.

https://rcjetwerx.com/product/rt-6s-4400-70c/

[janmb]

First of all, this is very well flown by Justin. I will definitely give you that.


While people are certainly very welcome to experiment and tune their models however they please (in fact a very good thing), I personally would strongly advise against trimming/mixing canards pitch up in order to achieve high alpha flight with less elevator stick pulling going on. It is in fact the exact opposite of what you want.

Why?

First of all because it defeats some of the purpose of the canards: Reducing the effective alpha seen by the main wing.

Secondly, because the need for canards to pitch up like this is a direct proof of a nose heavy CG.

An optimal setup would first of all be a far more neutral CG, slight DOWN pitch on canards, and slight up pitch on elevons. With correct CG, that setup will high alpha hands off. And without preventing the canards from doing their main job.

For reference, a good example of how canards deflect during high alpha on the full size can be found here: https://youtu.be/i8UPxieRZps?t=190

[Pogo]

My first 2 flights were flown with the last of my still useable Roaring Top 5000 45 c batteries, weighing 720 grams. The model balanced at 133mm with 34 grams of lead in the tail and seemed to fly well at that CG. I've since replenished my battery supply with 6 Liperior 5000 45c (thanks Richard!) which are heftier (and I hope longer lasting) at 780 grams.
Foam was removed to get the battery as far back as possible and the corners of the battery now protrude just slightly into the intakes- not enough for any ill effects I reckon. Everything else- rx, gyro, light controller, AB controller,10 A BEC and wiring is also to the rear. I was happy to see that the CG is about the same as before so no extra lead required despite the heavier battery.
Tom

[JLambCWU]

First of all, this is very well flown by Justin. I will definitely give you that.


While people are certainly very welcome to experiment and tune their models however they please (in fact a very good thing), I personally would strongly advise against trimming/mixing canards pitch up in order to achieve high alpha flight with less elevator stick pulling going on. It is in fact the exact opposite of what you want.]

Well being as the MODEL flies VERY well with my setup as shown in my video.
Being also as the REAL aircraft ALSO lands this way with canards deflected up, I HIGHLY recommend people try my setup with the MODEL.

https://youtu.be/xcl7zbXMm1w

[Pogo]

My first 2 flights were flown with the last of my still useable Roaring Top 5000 45 c batteries, weighing 720 grams. The model balanced at 133mm with 34 grams of lead in the tail and seemed to fly well at that CG. I've since replenished my battery supply with 6 Liperior 5000 45c (thanks Richard!) which are heftier (and I hope longer lasting) at 780 grams.
Foam was removed to get the battery as far back as possible and the corners of the battery now protrude just slightly into the intakes- not enough for any ill effects I reckon. Everything else- rx, gyro, light controller, AB controller,10 A BEC and wiring is also to the rear. I was happy to see that the CG is about the same as before so no extra lead required despite the heavier battery.
Tom

[janmb]

Well being as the MODEL flies VERY well with my setup as shown in my video.
Being also as the REAL aircraft ALSO lands this way with canards deflected up, I HIGHLY recommend people try my setup with the MODEL.
https://youtu.be/xcl7zbXMm1w

Yes, the full size uses canard pitch up in landing mode - and that's the only time it ever does. That is, ironically, done to reduce alpha, not emphasize it.

As I said, by all means, people should do as they please - and experimentation is always good. But you cheat yourself if not trying it the other way around. Nose lift should not come from the canards - that is a total misunderstanding of their purpose.

Also, there is no need to constantly wear out that shift key to get your point across.

[kallend]

Well being as the MODEL flies VERY well with my setup as shown in my video.
Being also as the REAL aircraft ALSO lands this way with canards deflected up, I HIGHLY recommend people try my setup with the MODEL.

https://youtu.be/xcl7zbXMm1w

That doesn't look at all like high alpha. That looks like it's about to land.