Official Freewing JAS 39 Gripen 80mm EDF Jet

[Mizer67]

Spit balling here but the blue LED controller weighs 11g, and is in the nose area. It doesn't do anything on this jet because all 3 lights are static. Why not replace it by a simple 3 way splitter?

Do you mean you just Y-d the lights into the receiver with a 3-way Y lead to remove the controller?

That I'd like to try. 8 grams is 8 grams. No big savings to be had, will have to be incremental.

I did relocate my receiver under the battery tray and moved the light controller back as far as I could to make a small difference in where the weight is located. Perhaps without the light controller I could move the receiver back further.

[kallend]

Do you mean you just Y-d the lights into the receiver with a 3-way Y lead to remove the controller?

That I'd like to try. 8 grams is 8 grams. No big savings to be had, will have to be incremental.

I did relocate my receiver under the battery tray and moved the light controller back as far as I could to make a small difference in where the weight is located. Perhaps without the light controller I could move the receiver back further.

My light controller turns the landing light on and off, so that function would be lost. Also I don't know that the position light LEDs have built-in current limiting, or whether that is provided by the controller.

Removing 11g from the light controller location will move the CG back by just 1.5mm

I'm leaving mine in place.

[Evan D]

The light controller like the various BB's and MCB's that FreeWing uses all have resistors in them to drop the voltage the LEDs see. Wiring them direct to receiver voltage will destroy them.

[kallend]

The light controller like the various BB's and MCB's that FreeWing uses all have resistors in them to drop the voltage the LEDs see. Wiring them direct to receiver voltage will destroy them.

Thanks for confirming that, Evan.

The current through a LED (or any other semiconductor diode) increases exponentially, not linearly, with voltage, so some method of limiting the current is always needed, such as those dropping resistors.

[KevinMar]

The light controller like the various BB's and MCB's that FreeWing uses all have resistors in them to drop the voltage the LEDs see. Wiring them direct to receiver voltage will destroy them.

Thanks for that, luckily I hadn't powered up my new setup. Blue LED box will be going back in 😕

[xviper]

The light controller like the various BB's and MCB's that FreeWing uses all have resistors in them to drop the voltage the LEDs see. Wiring them direct to receiver voltage will destroy them.

Yup. Been there done that. I always do servo testing before I assemble a plane. In the early days of lights, I used to "test" them by plugging them into the servo tester, which is the same voltage as what goes in and out of a RX. Instant light destruction.

[Evan D]

An alternative is to add a resistor in line with the LED. Very easy to do but I forget the resistance you need. It's not much and if you have an old blue box you could even remove the resistors from inside it but they are surface mount (very tiny) and not easy to solder for most people.

[HockeyMac!]

I think we can move the ESC back by about an inch as well

[Icarus the 2nd]

My light controller turns the landing light on and off, so that function would be lost. Also I don't know that the position light LEDs have built-in current limiting, or whether that is provided by the controller.

Removing 11g from the light controller location will move the CG back by just 1.5mm

I'm leaving mine in place.

John, the nav lights don't have a built-in current limiting, they are just plain 1w leds. I had to replace on already. It's the FW led controller that has the resistors built-in, providing around 3.3V for each port on that controller

[TangoVector]

Hi all,

My Gripen won't fly until March I guess, but that doesn't stop me from making plans. My setup will be with pitch only on canards, assisted by a gyro. There will be pitch on elevons also, of course, but no roll on the canards. I have the Eagle A3-L laying around and was planning to use it, but I'm not sure if it is up to the task. There is a good chance that down the road I want the Gripen close to tail heavy (unstable) and letting the gyro actually keep it stabilised. This will be a slow process getting there, but I hope it will be fun. Probably won't work and not worth it, but anyhow, In that configuration, the signal from the rx will maybe be 20% while the stabilisation has greater authority. So I wonder if the A3-L will be fast enough, both in computing power and number of corrections per second (resolution?), or should I get another gyro, and in that case which?

[Airguardian]

If you want to experiment with tail heaviness, a typical gyro will allow you only to get 'very slightly' tail heavy while still being controllable. If you overdo it, it will not be fun.
For proper 'unstable setups' I guess one should consider high-refresh-rate-capable gyros AND servos... and the power supply system needs to be able to handle it. Something like 100-333Hz capable digital servos and gyro with the right setup may do the trick. I want to experiment with that myself and recently bought some high end mini servos for this very purpose.
Was planning to use Guardian gyros but now can't find them anymore since EagleTree closed down... May be able to use some of the units I still have but otherwise I will have to look for other available options. Cortex Pro and iGyro come to mind. Also if the Aura AFCS supports high refresh rate it may be a very good and cheaper alternative.

[4923crew]

Pictures of my Freewing JAS-39 Gripen with weapons and armament.

[KevinMar]

Trying to solder extensions to the ends of wires of my new FMS 80mm power unit. I’m using a Hakko at 720F, 63/37 solder, and flux on the joint. I cannot for the life of me get any solder to stick to the copper on the motor side. Any tips?

[rms]

Trying to solder extensions to the ends of wires of my new FMS 80mm power unit. I’m using a Hakko at 720F, 63/37 solder, and flux on the joint. I cannot for the life of me get any solder to stick to the copper on the motor side. Any tips?

Use a solder heavier tip witch store more heat.
I was struggling a lot to I got a bigger professional solder iron.

[TangoVector]

Cortex Pro and iGyro come to mind. Also if the Aura AFCS supports high refresh rate it may be a very good and cheaper alternative.

If Cortex Pro or iGyro is the way to go, coupled with high-end servos, my interest in making it unstable just vanished. I think I rather buy another plane of some sort and enjoy that, there are many to chose from! Back to the thinking cave!

[Evan D]

Motor wires have an enamel coating you have to remove.

[radfordc]

Ah it was you haha! Do you think we could cut more foam and sit the battery back further?

Maybe, but the battery will begin to protrude into the intake duct. On mine I can just see the battery when looking down the intake. I did remove the louvers from the cheater duct on the bottom of the plane to improve air flow into the fan.

[radfordc]

My setup will be with pitch only on canards, assisted by a gyro. There will be pitch on elevons also, of course, but no roll on the canards. I have the Eagle A3-L laying around and was planning to use it, but I'm not sure if it is up to the task.

I'm using the Eagle A3 Pro gyro on mine...on elevons only. No way to add in the canards in pitch only with the Eagle gyro, that I know of. You will need a second gyro for the canards or go to a higher end gyro like the Aura.

[kallend]

I'm using the Eagle A3 Pro gyro on mine...on elevons only. No way to add in the canards in pitch only with the Eagle gyro, that I know of. You will need a second gyro for the canards or go to a higher end gyro like the Aura.

You can buy two A3 Pro gyros (one for the elevons and rudder, one for the canards and nosewheel) for the price of an Aura and still have $$ left over.

[janmb]

If Cortex Pro or iGyro is the way to go, coupled with high-end servos, my interest in making it unstable just vanished. I think I rather buy another plane of some sort and enjoy that, there are many to chose from! Back to the thinking cave!

A Cortex Pro is a big investment, but you will never regret it. Talk to Amir at HAB in Ljungby for a good price 😎