Official Freewing JAS 39 Gripen 80mm EDF Jet

[Evan D]

Before the TVs my Gripen was flying awesome. After I put them on it was still awesome. I did turn the pitch mix down a slight bit but it tracked perfect and had no change in pitch with or off throttle. The only down side was I was going through the battery much faster.

Later last week I went back and cut the nozzle foam and put on the plastic nozzle from the old rear fuselage. I also redid the centering of the TV servos and up’ed the yaw rate.

When I flew it Sunday it was horrible. Flew very nervous and would come out of a pitch flip tilted. Also it dove on throttle and pitched up off. A turn of the ball link fixed the pitch issue and moving the CG forward 3mm calmed the twitching.

Lookin at the TV on the bench maybe glueing the plastic nozzle may have changed the exit just a little. I re centered as best I could and have 8 sets of batteries for today.

Mo better. A tweak here a tweak there and pushed the battery back to the more tail heavy spot and all’s well. Surprisingly even one turn of the yaw ball link on the TV makes a lot of difference in feel. As I’ve said before the new TV ball has a lot more authority than previous FW TVs.

And yaw really effects roll...

[janmb]

I also installed a gyro and I'm finding it to be very sensitive to gain, meaning about the point the gain is high enough to stop the wings from rocking I run into problems at high speed because of too much gain! I'll get it sorted hopefully, or just put up with a bit of wing rock at a lower gain. Also it could really use a speed sensing gain adjustment. The gyro I put in here is overkill really (iGyro SAT) but it has a crazy amount of adjustment potential.

Unfortunately, conflict of interest for gain settings between high vs slow speed is pretty common, and very common for deltas. The rates/gains you need for really slow, high alpha stuff are simply so large that oscillation during normal/fast flight is unavoidable.

The only good solution to that is, as you are already thinking, is IAS input that automatically adjusts the gain. I believe the iGyro actually supports that internally.

For my part, I will be using a standalone IAS and program gain adjustment based on telemetry value from the radio.

[Husafreak]

I finally got some lighter batteries, ZEEE 4000, and it is fun to fly the Gripen with them! Initially I was only flying with 1 lb 12 oz Thunder Power 5000 packs all the way aft and 100g lead on the tail, 4 minute flights. The 4000 packs are much lighter and more fun to fly, losing 30 seconds of flight time is a worthy trade off IMHO, I may slide that 4000 all the way back and lose as much lead in the tail as possible, and regain even more performance. Honestly, I don't find it to be too bad as it is but lighter is better applies especially on this plane.
I also installed a gyro and I'm finding it to be very sensitive to gain, meaning about the point the gain is high enough to stop the wings from rocking I run into problems at high speed because of too much gain! I'll get it sorted hopefully, or just put up with a bit of wing rock at a lower gain. Also it could really use a speed sensing gain adjustment. The gyro I put in here is overkill really (iGyro SAT) but it has a crazy amount of adjustment potential. Some of these MRC EDF jets don't need gyros and some lock in completely with gyros but this one is a bit like my 90mm F-104, it may never be perfect.

[kallend]

Airguardian What I mean is like any man and machine interface, for lack of better terminology, the mind meld with the plane. And yes, maybe some level of feedback in the vortices displayed in the smoke. Maybe?

There's a feedback loop: plane - eyes- brain- hand (stick) - radio - control surfaces - plane (repeat).

The tighter and more accurate the feedback loop the better it "feels".

I have a few planes that "feel" really good, and others where the "feel" is rather sloppy.

[SanExup]

KevinMar Your Gripen looks badass!

[SanExup]

Airguardian What I mean is like any man and machine interface, for lack of better terminology, the mind meld with the plane. And yes, maybe some level of feedback in the vortices displayed in the smoke. Maybe?

[Airguardian]

The low level aerobatics, high speed passes, and high angle banking are the best. Just to get that visual cue, it probably adds to the feel of the inputs?

Thanks!
But what do you mean exactly by 'adding to the feel of the inputs'?
You mean as in the smoke helping to control better the jet?
To some degree, yes... you have more of a 'visual' idea in terms of angle of attack, efficiency of flying and how 'abrupt' the maneuvers or changes in trajectory are, and certainly can use that to fly more smoothly. :)

[TangoVector]

...will be flying Cessna 182's with rocket pods...

-Rocket pods!?! You will be lucky! We will be so poor that the air force will use drones, and not the fancy 5" type, nooo, it will be tiny whoops with little rocks on kamikaze-missions for us.

With a reference to Monty Python

[Mizer67]

Yeah I combed the internet for different pictures of 6002 and it's a dark blueish grey. It changes a lot depending on the light and maybe repaints. It looks a lot like Vallejo 71.304 in some pics, but much darker in ones like this

Agree. Lighting makes it challenging to get a match. I considered Vallejo 71.308 as well. Seemed a little too "purple" to me.

[Pogo]

Yeah I combed the internet for different pictures of 6002 and it's a dark blueish grey. It changes a lot depending on the light and maybe repaints. It looks a lot like Vallejo 71.304 in some pics, but much darker in ones like this

Yes, the lighting makes a huge difference. Such a great looking scheme though, whatever the lighting.
Tom

[Pogo]

Ha! I live in Southern California and fly at a field where it regularly gets above 100F or 37C in the summers 🤪

We get there sometimes too (feels like because of the humidity)- but yours is a dry heat, lol
Tom

[KevinMar]

The actual color isn't black, it's a more of a dark blue-grey. I used Vallejo 71.304 recently and that's a close match.

Probably not much better than black, but hoping the 71.304 doesn't popcorn in the FL summers also.

Yeah I combed the internet for different pictures of 6002 and it's a dark blueish grey. It changes a lot depending on the light and maybe repaints. It looks a lot like Vallejo 71.304 in some pics, but much darker in ones like this

[Mizer67]

I like that scheme a lot and you've rendered it beautifully! I considered it too but the black bits scared me off due to the popcorning. Where are you at- does it get hot?
Tom

The actual color isn't black, it's a more of a dark blue-grey. I used Vallejo 71.304 recently and that's a close match.

Probably not much better than black, but hoping the 71.304 doesn't popcorn in the FL summers also.

[KevinMar]

I considered it too but the black bits scared me off due to the popcorning. Where are you at- does it get hot?
Tom

Ha! I live in Southern California and fly at a field where it regularly gets above 100F or 37C in the summers 🤪

[Pogo]

This version is really nice and original. Really nice.

Thanks for the kind words Miroslav.
Tom

[Pogo]

Here is my completed Gripen! I went for a winter camo scheme taken from Gripen 6002, and added the Ghost symbols used by the No.1 squadron which had been based in Angelholm, in hangers now occupied by the car manufacturer Koenigsegg.

I like that scheme a lot and you've rendered it beautifully! I considered it too but the black bits scared me off due to the popcorning. Where are you at- does it get hot?
Tom

[Evan D]

True. Not much scale about mine anyway. I just didn't like the look of the foam nozzle.

[KevinMar]

Haven't flown mine with the TV yet. I like your nozzle, but I personally don't hate mine that much. If we were going for perfectly scale, we wouldn't put a 2 axis thrust vectoring system on a Gripen in the first place...

[Evan D]

Nice. Have you flown it?

I really dislike the look of the TVs nozzle.

[KevinMar]

Here is my completed Gripen! I went for a winter camo scheme taken from Gripen 6002, and added the Ghost symbols used by the No.1 squadron which had been based in Angelholm, in hangers now occupied by the car manufacturer Koenigsegg.