Official Freewing JAS 39 Gripen 80mm EDF Jet

[Airguardian]

Nice!
I wouldn't have thought of that!
Thank you for the ideas Tango! :)

[Mtpisgah99]

YES, hack the foam!

My Gripen tail is getting there.

make sure you add sleeve between tail section and main body. i used a CLEAN 80mm edf fan, you don't need the whole barrel, may be 1/2 or 3/4 to add strength and transition of two parts. don't use too much glue or will adds weight to tail.

[TangoVector]

I use a 9mm cutting blade knife because the blade bends easily. It's the one that you can break off small sections from, but I don't do that. I extend the knife all the way and by pushing it, it bends and it is very easy to shave the foam. It is like using the cheap version of a wood carving knife. Then I use a Dremel for some of the precission-work, but the sharp knife is approx 95%. I can take a picture next week, am away at work at the moment.

Oh, and I cut the tail in half for easy access, it was easy with the sharp knife and it will not show once glued back.

[Airguardian]

Nice!
Could you ellaborate on your technique to shave the duct foam?

[TangoVector]

I'm considering hacking the foam to install the EDF much further aft to really get rid of the useless ballast while still being able to use bigger batts.

YES, hack the foam!

My Gripen tail is getting there.

[Airguardian]

You should be good then.

That said, if you have not installed the EDF yet, try to move it aft, or you will struggle to get decent CGs.

I moved mine as aft as I could without hacking foam open and despite the EDF and ESC being heavier, and me still having 130g of ballast in the tail it's really not enough.

I'm considering hacking the foam to install the EDF much further aft to really get rid of the useless ballast while still being able to use bigger batts.

[Skosh25]

Be careful with flight time with that EDF. Use 4Ah batts at the very least, the 3Ah ones bite me on the back.

Thanks for the heads up- I plan on using 4500s.

[Airguardian]

Be careful with flight time with that EDF. Use 4Ah batts at the very least, the 3Ah ones bite me on the back.

[Skosh25]

Just ordered the JF/ HET 700-60-1865 combo from Efflux. Can't wait to see how she performs on 8S. I fly at 5500' so looking forward to the extra thrust.

[Mizer67]

This is nothing new. I had hoped this wasn't the case for the Gripen but I guess I'll have to deal with it. My FMS F7F was so bad, I had to do an inverted pass just to get the nose gear door to close. I've changed retract motors and still the same. Now, I just don't bother and let the door/wheel hang done a bit during flight. The FMS 1700mm Corsair is the same. They need to make stronger retracts.

I have to do that with the Mirage from time to time to get the nose gear door to close.

Even my F-18 seems to have caught this bug on the nose gear door. I even swapped the retract with a new one to no effect.

Fortunately, except for the Mirage, pulling vertical seems to do the trick.

[Reborn8]

This!

A little bit of me dies whenever I read someone talking about whether or not a model NEEDS a gyro.

Your car doesn't NEED power steering or cruise control either, but it is damn nice to have anyway. It is virtually never about need.

Well said!

[hirth90]

.

[xviper]

This is nothing new. I had hoped this wasn't the case for the Gripen but I guess I'll have to deal with it. My FMS F7F was so bad, I had to do an inverted pass just to get the nose gear door to close. I've changed retract motors and still the same. Now, I just don't bother and let the door/wheel hang done a bit during flight. The FMS 1700mm Corsair is the same. They need to make stronger retracts.

[Gary S.]

My solution has been to take off, gain some speed, flip the gear switch then pull into the vertical. The reduction in speed as it climbs reduces the air pressure and allows the doors to close fully.

Thats what I do also. seems to work well.

[Mizer67]

Solved - Gear Doors Stay Open in Flight, Added Servos

I found the problem to be air pressure in flight stalling retracts before fully closed, started after about 10 flights. I removed all the mechanical door links, springs, push rods, etc. and replaced them with added servos and links from EF2000 Eurofighter gear doors and a sequencer just for the servos to get max throw and added a 5 second down delay to the gear channel in the TX to allow the main doors to fully open. Now that the doors close reliably, my Gripen flights are back to normal fun and much better. See pics.

Yeah, mine do that too and stall out before fully closing. I upped the BEC voltage to 5.5V without effect on the gear.

My solution has been to take off, gain some speed, flip the gear switch then pull into the vertical. The reduction in speed as it climbs reduces the air pressure and allows the doors to close fully.

[radfordc]

If the doors weren't so inexpensive, I'd just drill a hole and replace the plastic pin, which breaks too easily with either carbon fiber rod or wood.

I've done that to mine. CF pin.

[RCMC]

Solved - Gear Doors Stay Open in Flight, Added Servos

I found the problem to be air pressure in flight stalling retracts before fully closed, started after about 10 flights. I removed all the mechanical door links, springs, push rods, etc. and replaced them with added servos and links from EF2000 Eurofighter gear doors and a sequencer just for the servos to get max throw and added a 5 second down delay to the gear channel in the TX to allow the main doors to fully open. Now that the doors close reliably, my Gripen flights are back to normal fun and much better. See pics.

[cmuchna]

Hi guys - I'm flying turbine models but this edf is just SUPER !!!

[John lueke]

I have been flying mine on an FMS fan on 7s from the start with additional dorsal cheater vents. I thought I would try 6s and tape over the extra cheaters to see what the difference was, but decided there was no point to going backwards to a lower power system. I only got a few flights in before the flying weather got terrible, but used the downtime to repaint to a high visibility scheme and print stuff to hang on the wings. The waste heat fro the 3d printer helped to heat the house.

[Mizer67]

The stock doors feature magnets. ;)

Didn't realize that....thought it was just the latch mechanism holding them shut in flight