Originally Posted by Castel101

Bri6672, great that your maiden went well. I have my CG at the recommended location here, 162mm, right side up gear down. My guess is that Jetnfast is correct, it might be adverse yaw what is making your nose pitch up. The manual recommends aileron differential, did you added this to your setup?

Mine doesn't present this behavior in turns, it turns very nicely.

Thanks man,

I didn't setup the differential, and honestly I didn't notice it in the manual. That might explain the turns but I'm more concerned about the take off. There was a bit of a crosswind and I have flown other jets that just don't like cross winds. Has anyone flown it in a crosswind? Curious if that might just be its characteristic.

I could see crosswinds being an issue with the F-4 based on the design. I haven't flown mine since it is still in the box, so I will let others answer that for actual crosswind encounters.....I would say though try and fly on a calm day and use about half flaps on takeoff, I bet that will help. Make sure it has plenty of speed before rotation so there is ample airflow over the control surfaces.

Not my first rodeo when it comes to speed on take off! It went into the air completely on its own. I don't like half flaps on take because it can bring the jet off the ground before you might want it to. I like my jets hauling butt before they go airborne. Hopefully someone else that has delt with crosswinds on this specific jet could bring us their feedback, based on earlier flight reports I didn't think it was an issue despite the F-4's design which would seem to play some tricks with a crosswind.

As far as the calm day thing, well this is not a flagship jet for me, it's my daily flyer and I expect it to fly in most conditions.

anyone looking for another airframe. im about to put my new in box plane on the classifieds for 350 shipped

Man this poor thread seems to have just died....

So I am going to give it another go this weekend. I added the differential, toned down the rudder and moved the cg forward just a tad. I think on take off I might have been holding to much Nosegear/Rudder and it might have caused the roll.

The crazy thing is my jetfan seems to like the F-4 more than it did the Habu, I wasent doing any high speed passes but I flew for 3 minutes and used less than 40% of the capacity of the packs, It also looked to be a bit faster than my Habu (Habu dopplered at 129) but it might just be the sound from the bifurcated exhaust (the Habu was pretty silent).

So weather permitting I will ring her neck this weekend.

Does anyone know if there's an Asia-based vendor that carries the F-4? I'm located in Taiwan so ordering it from E-Flite or any other US vendor isn't a feasible option due to the shipping cost. RC Castle in Hong Kong carries the Habu but not the F-4. Any suggestions? Tks!

Kevin

Originally Posted by bri6672

Man this poor thread seems to have just died....

So I am going to give it another go this weekend. I added the differential, toned down the rudder and moved the cg forward just a tad. I think on take off I might have been holding to much Nosegear/Rudder and it might have caused the
The crazy thing is my jetfan seems to like the F-4 more than it did the Habu, I wasent doing any high speed passes but I flew for 3 minutes and used less than 40% of the capacity of the packs, It also looked to be a bit faster than my Habu (Habu dopplered at 129) but it might just be the sound from the bifurcated exhaust (the Habu was pretty silent).

So weather permitting I will ring her neck this weekend.

4 me 165 was the sweet spot 4 cg

Originally Posted by bri6672

Recieved my F-4 on Wednesday and flew the maiden today. It went together really quickly, very easy build especially if you've built the Habu.

Mine is 8lbs with a 6s jetfan setup. I put the cg twords the rear of the reccomended. On take off it leaped off the runway nose up and rolled right, I quickly corrected and it climbed out fine. The nose goes up and the tail dips when pulling into the turns but other than that it flys ok.

Normally this is a sign of being tail heavy (along with the take off leap) but I'm ahead of 6 1/8th inches.

I read that another person had this happen earlier in the thread but is anyone else noticing this?

If the nose on these "delta" style wings goes up when you are still a bit slow, it will go into a high-alpha condition and it makes control difficult until you can gain some airspeed.
I lost an A-4 - and almost an F-4 due to this. My F-4 doesnt need a lot of speed in order to start hopping off the ground, so I just make sure that im NOT pulling any up elevator on the take off roll until it is moving along and ready to fly. It OFTEN jumps off before I think it should - but what are ya gonna do???
You didn't comment on your landing, so I guess that was not an issue.
Most of us have moved the CG way behind the recommended and she really is a different bird. I use a notch of flaps on take-off - just so the inboard wing stalls first if it does come off too soon. Its only about 15-deg.

Im glad its your daily driver - it is worth it. Just go fly the heck out of it and get used to it.

Enjoy!

Just put 3 more flights on mine yesterday. 2nd flight I was at 170mm with a 6s3300 and testing slow speed at full flap. Lost perspective in the turn (and alt) and the nose got too high. Full power and full down and it went over its back (I'm sure due to the power). Plus, I was very slow. Took about 500' to recover. After leveling off, I pulled flap and shook her out at speed and she was fine. It was a little more sensitive on final, but got her down no issues. Used full flap.

The kicker to me is that it looks nose heavy carrying all that up elevator, yet you start to feel the CG when its back at 170.

More testing for sure.

Originally Posted by f82fan

If the nose on these "delta" style wings goes up when you are still a bit slow, it will go into a high-alpha condition and it makes control difficult until you can gain some airspeed.
I lost an A-4 - and almost an F-4 due to this. My F-4 doesnt need a lot of speed in order to start hopping off the ground, so I just make sure that im NOT pulling any up elevator on the take off roll until it is moving along and ready to fly. It OFTEN jumps off before I think it should - but what are ya gonna do???
You didn't comment on your landing, so I guess that was not an issue.
Most of us have moved the CG way behind the recommended and she really is a different bird. I use a notch of flaps on take-off - just so the inboard wing stalls first if it does come off too soon. Its only about 15-deg.

Im glad its your daily driver - it is worth it. Just go fly the heck out of it and get used to it.

Enjoy!

Landing was fine, I have an A-7 and it had some of these same issues but the cg helped it out, I'll get her figured out, just got to fly the heck out of it and figure it out.

hey there folks. I'm still plugging away at my F-4. I have made a few changes. Mainly to a 90mm fan. I now have the CS 12 blade 90mm fan installed, duct work done and she sounds wonderful. This has been complete effort. I've also had to go from my original 1400kv motor to a HET Typhoon 1700mah inrunner. On 6s she is pulling @87 amps and 1800 watts. I can't be sure at the moment... My watt meter wasn't up to the task and I'm waiting on a new more robust unit. I've also splashed and installed a 180/200 amp ESC. All of this adds weight. Phew. One thing I really wanted to be sure of was air flow and cooling over the speed controller so I've cut out the top of the duct work to allow the cooling fans to have air blown (at typhoon speeds) over it. All of this has been sealed and taped up using not duct tape but high tac hinge. Strong stuff to be sure.

I'm now working on the rudder installation. I'll post photos soon. It's good to see where everyone is putting the CG. It's heavy with the batteries and I haven't the wings on or the retracts installed. Go Team F-4!

Hmmmmm. I hope it works out for you! I would have tried to find a lighter 90mm fan like the Jetfan. This plane is a handful when heavy.....Or so I've read.

No need for a 180/200 amp esc, that is complete overkill and adds additional weight to an alreadt CG/Weight critical jet. I suggest going with a max of 120 amp esc, that is all you'll need based on the numbers your setup is pulling. A castle 120 would be ideal, plus it would have data logging to help you see accurate numbers on your setup.

I'm using a Turnigy K-Force 100A in my F-4, it does get a bit hot as I'm pulling 90+A but I have 25 flights on it without any issues so it has proven itself to be working fine.

So flight number 2 and 3 today...

The owners manual came with an addendum that seemed to want quite a bit of up for the elevator neutral position. In flight number one she nosed up in the corners and leaped off the runway on take off. I moved the cg slightly forward thinking that was the problem. Well that was definitely not the problem, flight number 2 was a nightmare! The elevator was non responsive and would just stall and roll over with to much, it took everything I had to get it on the ground. So I then moved the cg back knowing and got rid of that manufacture reccomended up trim

Flight number 3 finally a normal take off!! And like so many have said it was way better (this was at 6 1/8 cg) it was the best it has flown but as I was bringing it around from base to final the elevator stalled again trying to pull up the nose. So another stall and another bit of crazy piloting to get her back on track.

So next time around I'm going to 6 3/8 cg. I can't believe how wrong eflite got the cg on this model. I would bet anything that most of the losses of this jet have come from being to nose heavy.

I also used 30% differential and the nose up issue disappeared.

By the way, I don't know why but the jetfan 80 is working way better in the F-4 than it ever did in the Habu, not sure why, I figured with the bifurcated thrust tube it would be less efficient but it's really come alive!