Sländan

Hi! I just got my hands on a perfomance model Jas-39 1/8 scale! My biggest plane so far. But now to a problem I have: I can't find where the cg should be? Is there anyone that have any ideas?

Art ARRO

My Feedback: (5)

Note that there are several versions of the JAS-39 available and your CG location is dependent on which one it is. I don't believe that this model exists in 1/8 scale as the ones by Jet Legend and Skymaster/Extreme are 1/7 scale. I have and fly the SM/Extreme version and used the CG location provided by Joeflyer and RCJets-63 with success. My only change was to limit the throw on the canard +/- 10 degrees or less and have it active during all flight conditions, takeoff. flight and landing. Some pilots elect to lock the canard for landing.
Scroll back to the beginning of this thread for all info including the CG. Warning, do NOT fly this jet tail heavy. Good luck with your Gripen.
Rgds,
Art ARRO

Sländan

It's from Performance Models and it's in scale 1/8 so I don't think it helps to take the cg they have on theirs because they are refering to the larger scale 1/7 and 1/5.

wernerfischer

Dear Jim how have you been/

well could you help me with a doubt about the gripen CG? mine is located at 140 mm and i had to add a little weigth in the nose, but i have noticed that the nose is down a lot with this weigth.......some people told me that is better to start to fligth with the nose heavy, on the other hands in my other jet sabre dod i left the nose a little bit heavy not to much as gripen is. Please help me cause i want to save my airplane and i do not want to broke in the fisrt fligth.......did you understand me? sorry if my english is not understandble ......thank you very Much!

wernerfischer

Dear Jim how have you been/

well could you help me with a doubt about the gripen CG? mine is located at 140 mm and i had to add a little weigth in the nose, but i have noticed that the nose is down a lot with this weigth.......some people told me that is better to start to fligth with the nose heavy, on the other hands in my other jet sabre dod i left the nose a little bit heavy not to much as gripen is. Please help me cause i want to save my airplane and i do not want to broke in the fisrt fligth.......did you understand me? sorry if my english is not understandble ......thank you very Much!

rcjets_63

My Feedback: (4)

Replied via PM.

wernerfischer

TKS dear JIm.

Jonas Bergström

Hi
The maiden is done of our 100 % composite Gripen in scale 1/6.
Niclas has the courage to fly it.
Everything's work perfect .


//
Jonas

rcjets_63

My Feedback: (4)

Congratulations on your successful maiden flight!

Jim

Rliebl

Hi,

we made a new short Video clip from my Gripen, enjoy

https://www.youtube.com/watch?v=vkZSssd56Hc&feature=youtu.be

NRTM

Here is a short report about our testflight.

We did our testflight at Feringe airfield in the south of Sweden.
The plan was to fly on friday but a leaking hopertank destroyed our plans.
On saturday we hade perfect conditions for a testflight at the begining,but the wind was geting stronger and turned 90degrees and we had to cancel again.
Last day sunday was perfect!
For takeoff i used Jannes setup described in the airworld gripentread,but i got my expected gripen jump anyway,but i think that will not be a big problem after
some fligts and tuning.
The flight was only 4 minutes long but we only needed to know if it could fly.
I did not retract the gears to not take any unnesecery risks before landing and the landing was one of the easyest i ever done!

The conclusion was that it was a litle tailheavy and sensitive on elevators,but after some more tuning and testflights i think it will fly realy good.
Unfortunately our filmcameraman had to leve on saturday so we only have pics from the flight,but next weekend it`s time for the next flight/s
with filmcameras.
www.jetsweden.se
Regards
Niclas and Jonas

NRTM

Some clips from last weekends test flights with our 1/6 Gripen..
We had some problems with the geardoors so we did the second flight with maingears out.
There were some crosswind that maked it difficult to do trim to not "jump" at takeoff.

https://www.youtube.com/watch?v=VNG3-FYXbZg
https://www.youtube.com/watch?v=kqH860DxZvE

There are more about our project at www.jetsweden.se

/niclas

Rafale

My Feedback: (2)

Congratulations on the test flights Jonas. I am still following and looking forward to when you start producing.

Best Regards
Pierre Fouché

NRTM

Hi Pierre..

We have slowly started the production of the last three of the five first.

Send me a pm if you want to know more.

regards
Niclas

rcjets_63

My Feedback: (4)

Congratulations on the flights, Niclas. You are getting the plane dialed in nicely.

I see (and heard) your Jeti DC-16 radio in the videos. Are you using a Central Box? What sensors are installed?

Also, regarding the production of kits, don't forget that I want one too! :-)

Jim

NRTM

Thanks Jim.

I use a R18ex reciver and a max bec 2d plus ex and no sensors so far.
I am suprised over the lowspeed caracteristics and as you saw it is easy to land.
We have already counted you in for a kit,so let us know when you are ready so we can give you an aprox dilivery date.

Regards
Niclas

Techspy

My Feedback: (1)

Hey Guys,

I am just finishing a Jet Legend JAS EDF build. Actually, the only thing left is the paint and I am not sure if I will maiden it first or not. Anyway, I keep seeing people say that the Jet Legend and the Skymasters are the same but I see some differences in the picts I look at. So what about the CG for a Jet Legend? I have not been able to locate a manual for it and right now have it setup as in the Skymaster at 140mm from leading edge of the wing root where it touches the fuse. It is balanced right at 140mm with the gear down and is probably 135-136mm with the gear up. Does this sound correct?

I just tested today with 14s 5000mah, and a Dynemax and got 7800 watts and 154 amps and has an AUW of 24lbs. This one flew with 4400 watts and 109 amps at the same weight so I am hoping mine will have descent authority.

https://www.youtube.com/watch?v=KrTgJuGU9sA

Thanks for any info.

rcjets_63

My Feedback: (4)

140mm should be fine. If you have also set up the plane with the control throws shown in the manual, you might also want to check early in this thread for recommended throws and expo settings. The throws recommended by SM for ailerons are TOO sensitive.

Regards,

Jim

Rafale

My Feedback: (2)

Hi Techspy

I agree with Jim on the CG. Mine is also arround 140-145mm. A have about 7mm up and 5 mm down on the ailerons to give very smooth aileron control with long slow-rolls. Also installed a ACT Fuzzy pro 2 ch gyro on the nose gear and rudder to keep the heading on take-off and landings. She is a beaut since 2011 now. This weekend it's Oudtshoorn Scale again and she'll be there.
I know Jim has a great setup with a gyro described aerly in this thread. Believe me this jet needs some special control. Although me and Jim talk about the Skymaster jet. The Jet Legend caracteristics are the same.

Best regards
Pierre

Techspy

My Feedback: (1)

Thanks guys. I will double check the control throws and go with what you recommend. Just to be sure, does your CG change as much as mine with the gear up?

Also, I have the canards lock at neutral for landing and takeoff in conjunction with the gear switch. I think I will also add a mix to a knob to allow me to adjust the throw during gear-up flight. I have a Guardian stabilizer on the elevons and rudder, not the nose wheel or canards. I may put a gyro on the nose wheel.

One other question, how do you guys trim on your maiden? Do you leave the canards locked at neutral, trim the elevons and then activate the canards? I have flown several delta wings and canard EDFs (90mm size however) such as a Mirage 2000, 90mm JAS39 and Eurofighter so I have a little experience with the canards.

Thanks again.

sysiek

My Feedback: (176)

Hi I have video on YouTube with all throw and mix for landing ,this might help to ,look tooommmek and the gripen video .

E Squared

My Feedback: (2)

Techspy,

Looking forward to hearing how she flies, especially at 7800 watts. That's more than double what my TJ100 is producing in my JTM Viper. Good luck. Post some pictures and be sure to get some video of the flight.

Techspy

My Feedback: (1)

A quick test today with a luggage scale showed 17lbs of thrust. Here is a quick vid of a motor run.

https://www.youtube.com/watch?v=rSB_...fn930wRZr0H1Yg

Techspy

My Feedback: (1)

Ready for maiden. Maybe this week. A couple of picts.

E Squared

My Feedback: (2)

Very nice.