FEJ F-35 Maiden Update
 

Getting ready for maiden. Since there are not that many out there, was wondering if anyone could confirm CG and throws.

Mine came out at 38.5 lbs dry, UAT full. CG at 100mm per print.

Thanks,
David

You might try reaching out to Lowell Wexler. He is not affiliated with them anymore but I know he did own and fly one at one point, I think I remember hearing it flew considerable better with a gyro but not sure..

A couple of things I was advised to do: Split the nose doors to reduce the center of lateral area shift when the doors are opened. The steering rod is secured using e clips and they come off so use a wheel collar inside the strut to secure the steering rod. The set screw that limits the turn on the lower portionof the nose strut MUST be loctited and set in just enough to not lock the strut's compression, else if left too loose the strut can turn 90 degrees. A roll axis gyro is necessary when the forward main doors are opened during retraction and extension of the gear. (Those doors are 45 degrees to the airflow and can make for some very interesting moments.) Make sure you set up the forward doors to close in both gear positions as the flight envelope gets pretty unstable when they are open. Also make sure the forward main doors open exactly the same angle so as to minimize the differential roll that they initiate.
All this being said the JL F-35A is a very docile plane and lands very slowly. I was cautioned to use a 3 axis gyro and while I used an iGyro at first I have a futaba single axis gyro on roll only now, and it is activated on the gear switch, being active only when the gear are down. The F-35A has a great 'presence' in the sky and you will enjoy the flight envelope. A friend in Hawaii has one and he uses conditions to get flaperons transferring the roll control to the stabilators during the flap deployment, and the ailerons can be raised as flaps to cause an airbrake efffect. I find this all unnecessary, as the 35 lands vastly slower than even the JL F-22 with all the crowed surfaces hanging out, but each to his own.
Hope this helps,
Len

Sorry I forgot the CG data: We are at 13lbs 13oz on each main wheeel and 5 lbs 14 oz on the nose wheel. If you do the math and get the percentages and apply them to your total weight the CG will be very very close to where you want it. You have a larger total weight than the 33.5 Lbs here, but that is likely because I used a lighter engine than most would in this plane. My friend in Hawaii used a Behotec 180, and I used a JetCat Titan SE (160 size).

Len

Len, thanks for your feedback. The nose gear must be very different on the JL, probably more scale. Most of those components are not present on the FEJ version.
Ive been told its a ***** with gear doors open so Im planning on that. I did set up my main foreward gear doors to remain closed while gear is out. I have a Rhino on mine. Airframe is pretty beefy. I had to add a large battery at the nose to get CG. There is nothing I can move forward as most of the equipment is already under the cockpit floor. I got 8.1 lbs at the nose, 14 lbs on right wing, and 16 lbs on the left wing. Not sure why the 2lbs difference between wings, this is not right. This is my second set of Xicoy CG weights and I still think it is not working right.

I have considered splitting the nose gear door. As soon as I maiden it and feel good about it, I'm stripping it down and converting to a production version F-35A, with the split doors and a nice paint scheme.

I did have a couple of comments with Lowell a few years ago and I think he said it flew good, but was a bit elevator sensitive. What throws do you have on yours? On the FEJ "manual" it is not clear where to dimension from. Anyway, I set it up for "**** load","half ****load", and "quarter ****load" just in case.

thanks for your feedback!

You may convinced me to go for the roll control gyro. Headed to the LHS later today.

I have to say, this being my first 40lb size airframe......it was soooooo easy to install equipment! I could probably double the amount of fuel easily (or fly with smoke on for 5 minutes non-stop). Rhino looks tiny in there.

http://www.rcuniverse.com/forum/atta...mentid=2110384http://www.rcuniverse.com/forum/atta...mentid=2110385

Hi "Falcon", Sorry I forgot while I was researching all that stuff again that you had an FEJ and not another JL F-35A. Anyway the CG locations are likely close as the moments shouldn't change that much unless they put the gear in a different spot which is quite easy for FEJ to do! I am retrofitting an FEJ F-14 now to make it airworthy (read HEAVY as Hell!), and they do some very strange things at that company!

I heard the Xicoy CG transducers are having some QC issues, but mine seem fine with an accurate weight on them. They do drift over time in the powered on state though. A pain in the butt but still usable. That being said, you could just use an HD kitchen scale to check the lateral weight as 2 Lbs is pretty far off even for FEJ's wings. You don't even need to lift the opposite side unless you really need to record the weights for your file, as the 2 lbs is going to show up big time if it is really that different.

My control surface throws are HUGE, and I did exactly what you are doing on a 3 position rate switch. Eventually I move the rates closer to a central position as more flights are done, such that I end up with just using a mid rate unless the bird needs a touch more for landing. My experience with the F-35A is that it is a real puppy to fly and land, other than the times the gear are transitioning of course. I do find it is a tad less stable ('skitterish') when the gear are down and the forward doors are closed too though, so I leave the roll gyro on all the time the gear are down. I do think it could maybe even benefit from an additional gyro on the yaw axis too, but my style of flying is such that yaw rarely comes into play other than in aerobatics and ground handling...wrong I know but its the way I was taught, oh so many, years ago!

On the first flight I left the gear down until I was at altitude after the turn out from takeoff heading downwind since I had been warned about the roll axis instability. I was carrying too much speed so the cycle was incomplete, leaving the nose gear hanging out a tad. It was uneventful to the flight characteristics though. I slowed and cycled again upwind and the gear tucked away nicely. It was very noticeably roll unstable though as I didn't have the gyro engaged at the time, wanting to see for myself what it would be correcting. I immediately hit the gyro switch to mid rate after the gear was up, and noted it didn't need any stablization at that point though. So hence the gyro attached to the gear switch in my case. It didn't seem to want to tuck over and fall out of the sky though, but it does get your attention pretty quickly.

I moved my gear switch a year ago when I went to using a tray for my Tx. STUPID me forgot to move the gyro to the new gear switch!!! I ended up doing a no gyro landing on the F-35A's sixth flight as I wasn't mentally present enough (while fighting the aileron stick) to recall why the plane could be rocking around so badly. That being said I scraped a wing tip, which is a tad difficult to do on a 35 by the way! So not really much damage other than my pride and some grey paint. I mention this so you get a sense that it is not an impossible situation to land without a roll gyro. If you ever get into this situation please remember that smaller aileron inputs are better as roll PIO is a real danger as you begin to chase the plane's rolling. It became that I was simply rocking the plane from the stick to prevent the plane rolling itself. Had I remembered that the rudder rates were now where the gear used to be I could have gone to high rate rudders and had the gyro engaged! More pride shot! Anyway I hope your maiden goes as well as mine!

Enjoy,
Len

I have the fiberglass F-35 Lowel had and here is only short video of it... he mentioned the tail has tendency to dance a little but when I had Billy Edwards fly it we saw none and no change when he used flaps or gear he was petty happy...now that I read this I will watch to see what happens with yours mine is just sitting cause I keep getting involved in other Jets ... 40 sec. mark https://www.youtube.com/watch?v=O0NJga6stdE

" I got 8.1 lbs at the nose, 14 lbs on right wing, and 16 lbs on the left wing"\

Another way to cross check your lateral balance is to lift it from the nose and tail using a string. Because if your Xicoy CG machine is correct..that could be fatal during your maiden flight.


Good luck and I hope it flies better than this one :(
https://www.youtube.com/watch?v=hhzoH17yf3o

We CGd a friends BVM Rafale and it had the same lateral CG issue.....flew great. You could easily tell if it really was that bad. Gonna play with it some tonight.

BTW if it goes as per that video we are happy! LOL

Falcon, check the calibration on your scales you could have one of the units that didnt get calibrated.

Could possibly be Keith, this is the second set though!

Ultimate jet guys calibrated mine, then I found out you can do it yourself in the tools menu, you just need a precision weight 5-10 pound weight works best from what they told me.

Well, I fell crafty today and decided to make a scale exhaust. BTW first time Im able to upload a pic from an Android device!http://www.rcuniverse.com/forum/atta...mentid=2110899

looking good, cant wait to see it in the air. You do any repainting on it?

Waco Sunday amigo

Not yet. Gonna fly it for a while first and get comfortable with it. But yes, plan is to give it to paint in Israeli LO Digital Camo scheme.

Gonna maiden it locally, then join you guys down south when it is setup.......I hate driving to Waco only to find out I have a broken air line! Yes, its happened before! :-)

Sounds good

digital camo....interesting. I have a F20 I want to do in digital camo.....let know henand show s yur technique

Exactly as described by others. Takes a lot of speed and elevator to lift off, but once it does.....it is nice. Was not able to retract the LG so I had to fly it the whole way, it was still very docile. Flew like an F-16 with gear out (yes like a pig!) I'm glad I put a Rhino in it because I was at the upper 15% of the power curve the whole time. Landing is super smooth and predictable.

It was very sensitive to rudder. Not sure if its me because I've never flown twin rudder before, but even a light touch of rudder would turn it upside down fast!

A short video from my cell phone. My buddy filmed from his Quadcopter, I'll upload that one when its done.
At the end of the day, I'm a happy camper. The thing has A LOT of presence in the air, unlike any other models I've seen.

David

https://www.youtube.com/watch?v=m-wQgBpvoLU

Sweet , congrats to you David, great lookin jet..
love the body English with landing at 2:51

Congrats on your maiden flight.. and this plane seems hard to rotate, have you considered takeoff with full flaps like a F-18?


p.s. also the big F-35 seems to takeoff with them..

https://www.youtube.com/watch?v=eQCg2IZcKPg

congrats, good to see it in the air