Official Freewing JAS 39 Gripen 80mm EDF Jet

[Marktur]

Hi All,
I have joined the ranks of Gripen drivers! :) Wife surprised me for my birthday on Saturday! After watching a bunch of YouTube videos, I'm really excited. What a speed envelope!

She's already built, but wow, I learned something about my wonderful Graupner MZ-24 radio: It doesn't have a Delta wing setting!!!! I have been fighting with programming for 3 days now (and I'm a software developer - shouldn't be this hard, LOL!) but the best I can get it is to have everything working perfectly EXCEPT I cannot reverse the direction of the elevators in the main wings. I used a 2-ail, 2-flap setup (that got me the closest) but if I try to change the direction of the wing servos, the ailerons are backwards. After lots of research and comparing to other name brands, I've realized that I'm missing this important software component...unless I'm missing something, so wondering if anyone is using Graupner?

I also have a new RadioMaster Tx16s (which I'm really taking a liking to), and an older JR X11...both seem to know what to do (delta wing), so today I'll get things setup on the JR since I am still getting to know the RadioMaster OpenTX software. I really think this is an amazing radio, and it binds with every type of receiver...but I'm going to do my range checking, etc. with some drones and planes I'm willing to donate to the airplane gods (if worse-case scenarios happen). I WILL put a Radiomaster RX and tiny battery as a "passenger" just to have a real "jet test", but will control everything with the JR. It has tons of telemetry (FrSKY) so I'll know everything and may migrate over once I'm comfortable.

ANYWAY...I'm up to page 17...so I have a lot of reading. Hope you don't mind if I ask just a couple of questions to get quick answers:
1. Best battery? I have several HRC 6000mAh that I would like to use. I use them in my Avanti and other 90mm's too. Love the extra minute of flight time! It requires about 3oz of weight on the tail to balance based on the marked CG on the wing. What is the recommended CG after you guys have all been flying for a bit? Still at the mark on the wing? I don't think 3oz is going to upset the weight of the plane....but would like feedback.

2. What are the best Hi/Med/Low rates (how much movement for aileron/ele/canards?

3. Any last minute tips before I maiden on Friday??? :)

Thanks everyone!
Mark

[Icarus the 2nd]

Hi all, a few days ago I maidened my 8S Gripen.

[TangoVector]

Hi All,

....
I also have a new RadioMaster Tx16s (which I'm really taking a liking to), and an older JR X11...both seem to know what to do (delta wing), so today I'll get things setup on the JR since I am still getting to know the RadioMaster OpenTX software. I really think this is an amazing radio, .
....

Great birthday gift!

The Radiomaster, or actually OpenTX, will have no problems when it comes to do fantastic mixes. I have many interesting ideas to try after Christmas with my unbuilt Gripen, but winter will stop them from being implemented until March...

Go back approx two pages and you will find the battery discussion being at peak. Go light seems to be the consensus, 5000mah max.

Good luck

[TangoVector]

Hi all, a few days ago I maidened my 8S Gripen.

Congaratulations!

First impressions on the setup?

[Airguardian]

Can't the Graupner radio make custom mixes?
To operate elevons you would need only 4 mixes:

PITCH to LEFT ELEVON
ROLL to LEFT ELEVON
PITCH to RIGHT ELEVON
ROLL to RIGHT ELEVON

Are you sure you don't have a delta mix? Sometimes they have a different name like 'elevon mix', tailerons... (NOT V-Tail!)

[janmb]

I'll take a look tonight, but with some foam shaving is it possible to move the fan unit back some? I haven't really touched mine sans for 3d printing ordinance, but I feel like the weight savings in the front and CG adjustment are the way to go. I remember one person cutting foam to move their battery back, that seems like a good place to start. I'm sure there's more we can do!

With some foam tuning, sure, it should be possible. We are carving foam and gluing new anchors for turbines after all, so why not a fan?

[Gary S.]

Hi All,
I have joined the ranks of Gripen drivers! :) Wife surprised me for my birthday on Saturday! After watching a bunch of YouTube videos, I'm really excited. What a speed envelope!

She's already built, but wow, I learned something about my wonderful Graupner MZ-24 radio: It doesn't have a Delta wing setting!!!! I have been fighting with programming for 3 days now (and I'm a software developer - shouldn't be this hard, LOL!) but the best I can get it is to have everything working perfectly EXCEPT I cannot reverse the direction of the elevators in the main wings. I used a 2-ail, 2-flap setup (that got me the closest) but if I try to change the direction of the wing servos, the ailerons are backwards. After lots of research and comparing to other name brands, I've realized that I'm missing this important software component...unless I'm missing something, so wondering if anyone is using Graupner?

I also have a new RadioMaster Tx16s (which I'm really taking a liking to), and an older JR X11...both seem to know what to do (delta wing), so today I'll get things setup on the JR since I am still getting to know the RadioMaster OpenTX software. I really think this is an amazing radio, and it binds with every type of receiver...but I'm going to do my range checking, etc. with some drones and planes I'm willing to donate to the airplane gods (if worse-case scenarios happen). I WILL put a Radiomaster RX and tiny battery as a "passenger" just to have a real "jet test", but will control everything with the JR. It has tons of telemetry (FrSKY) so I'll know everything and may migrate over once I'm comfortable.

ANYWAY...I'm up to page 17...so I have a lot of reading. Hope you don't mind if I ask just a couple of questions to get quick answers:
1. Best battery? I have several HRC 6000mAh that I would like to use. I use them in my Avanti and other 90mm's too. Love the extra minute of flight time! It requires about 3oz of weight on the tail to balance based on the marked CG on the wing. What is the recommended CG after you guys have all been flying for a bit? Still at the mark on the wing? I don't think 3oz is going to upset the weight of the plane....but would like feedback.

2. What are the best Hi/Med/Low rates (how much movement for aileron/ele/canards?

3. Any last minute tips before I maiden on Friday??? :)

Thanks everyone!
Mark

I am running mine with a jumper OpenTX radio, Their are some simpler routs to programing than the one I took, namely flight modes. But I would say I have great functionality including separate pitch trim for the canards (very handy) also using a hobbyeagle A3 Super gyro which handles the delta config very well no need to program that part.

[xviper]

I can't recall who did this, a few pages back.

That's what I meant by the foam in that location being quite thin. It's easy to carve right through to the intake tunnel. However, the battery should plug the holes.

[HockeyMac!]

Yea I think he mentioned that the battery plugged those holes for sure, or at least I’d hope!

Here’s the fan unit. Good point by janmb with our turbine friends carving foam out. Certainly seems doable and can make some mounts that are 3DP or very simply plywood. My take is alpha tried “balancing” this model for two setups. One with and one without the vectored thrust unit. I just hate to add dead weight and a 4-4500mah battery :)

[Evan D]

What’s this vectored thrust thingie you’re talking about?

[Mtpisgah99]

This is wrong, did a several test today, cold not get that difference. Was more around 2,4kg. But with a bigger fan/ motor you might need more air in.

But did another test several times, took of the rear,that increased the thrust from 2,4kg to 2,65kg but end diameter went up and the duct is very short...this is for testing purpose only ;-)
Did put the wire behind the fan in line and made a aerodynamic fearing aroud it. 2,4 kg thrust before and after. Will take it in the air and see if there is any difference.
If we want more thrust we need a bigger engine og fan that can move more air. Or go to bigger diameter fan.

did i missed the continuation of this topic?

[rms]

did i missed the continuation of this topic?

Did a flight test today without the rear duct. It has more trust but the plane did torque. Topspeed did go down, gess this is because the rearoutlet has bigger diameter. And this was for testing purpose only ;-))
It should be possible to move the fan unit backwards.

[Mtpisgah99]

Did a flight test today without the rear duct. It has more trust but the plane did torque. Topspeed did go down, gess this is because the rearoutlet has bigger diameter. And this was for testing purpose only ;-))
It should be possible to move the fan unit backwards.

i didnt know that small blades will make torque on a jet. i'll show you next time (friday presentation) what i did on mine. it didnt make a difference on jet performance except makes my battery hotter and drink a lot of batt. juice. before and after on a 4k 60c admiral batt. 30% vs 12% resp. same duration and flight patterns.

[radfordc]

I can't recall who did this, a few pages back.

It was me...and it flys awesome!

https://youtu.be/aqXY_VlKJcw

[radfordc]

Looking at the part at the rear of the compartment where it narrows, that part looks quite thin and you could easily cut right through to the intake channel. I suppose if you cut through, the battery could actually plug the hole.

Cutting through isn't a problem. Many jets have cheater holes in the intake. And, yes the battery does plug the hole in this case.

[HockeyMac!]

It was me...and it flys awesome!

https://youtu.be/aqXY_VlKJcw

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

[KevinMar]

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?

[KevinMar]

Alright just for fun I did some nose weight removal:
1. Replaced the 11g blue box with a 3.7g splitter
2. Removed 2 of the metal clips and some foam from the nose cone to remove about 4g
3. Made a 2.6g balance plug adapter to replace my 26g center burner 2s pack.

Will it make a big cg difference? Probably not, but for my setup that's 37.3g removed from the nose and cleared a little room to move the main pack back a little bit to where I previously had the center burner pack.

FMS fan unit coming tomorrow. The removal of the weight + more power + better CG + new canard mixes (less as a control surface, more as an air flow conditioner) should make for a fun and more scale flying setup.

[Icarus the 2nd]

Congaratulations!

First impressions on the setup?

thanks

I'm very happy with the setup, it has good top speed and efficient cruising speed. Although - because of the small intake section between the mains - I have a feeling that the unit is starving for some more air. I did choose this setup because of my not so perfect and only 80metres long grass runway and it does the job quite well!

Here's my maximum static test numbers with fully charged lipos

wattmeter gave 114A - my FRSKY sensor measured 113A
3200 watts
3120gr thrust

[rms]

i didnt know that small blades will make torque on a jet. i'll show you next time (friday presentation) what i did on mine. it didnt make a difference on jet performance except makes my battery hotter and drink a lot of batt. juice. before and after on a 4k 60c admiral batt. 30% vs 12% resp. same duration and flight patterns.

The torque was little, did turn to the left after slowflight/ go around. But with the stock rearduct it flies perfect again.
I`m amazed how nice this plane lands. Its very easy to findtune the sinkrate and do incredible nice landings with it. This is a very nice good plane to fly.