SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Feb 10, 2013, 08:58 PM
Registered User
bri6672's Avatar
San Diego
Joined Jul 2009
2,249 Posts
Quote:
Originally Posted by Castel101 View Post
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.
bri6672 is offline Find More Posts by bri6672
Reply With Quote
Sign up now
to remove ads between posts
Old Feb 11, 2013, 09:26 AM
Registered User
Jetnfast's Avatar
United States, MO, Warrensburg
Joined Feb 2008
2,256 Posts
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.
Jetnfast is offline Find More Posts by Jetnfast
Reply With Quote
Old Feb 11, 2013, 09:51 AM
Registered User
bri6672's Avatar
San Diego
Joined Jul 2009
2,249 Posts
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.
bri6672 is offline Find More Posts by bri6672
Reply With Quote
Old Feb 15, 2013, 04:31 PM
Cowboy of the skys
warbird_cowboy's Avatar
United States, Mt, Whitefish
Joined Oct 2010
1,083 Posts
anyone looking for another airframe. im about to put my new in box plane on the classifieds for 350 shipped
warbird_cowboy is online now Find More Posts by warbird_cowboy
Reply With Quote
Old Feb 15, 2013, 06:27 PM
Registered User
bri6672's Avatar
San Diego
Joined Jul 2009
2,249 Posts
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.
bri6672 is offline Find More Posts by bri6672
Reply With Quote
Old Feb 15, 2013, 06:38 PM
Registered User
Taiwan, 北市
Joined Dec 2008
781 Posts
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
kchen95 is online now Find More Posts by kchen95
Reply With Quote
Old Feb 16, 2013, 05:34 AM
guillows basher!!
Pittsburgh Allegheny, Pennsylvania, United States
Joined Feb 2004
962 Posts
Quote:
Originally Posted by bri6672 View Post
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
esb-help is offline Find More Posts by esb-help
Reply With Quote
Old Feb 16, 2013, 06:42 AM
Registered User
SPRING, TX
Joined Feb 2007
91 Posts
Quote:
Originally Posted by bri6672 View Post
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!
f82fan is offline Find More Posts by f82fan
Reply With Quote
Old Feb 16, 2013, 09:07 AM
low, left, & fast
nuts-n-volts's Avatar
Albuquerque, New Mexico
Joined Dec 2004
147 Posts
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.
nuts-n-volts is offline Find More Posts by nuts-n-volts
Reply With Quote
Old Feb 16, 2013, 09:48 AM
Registered User
bri6672's Avatar
San Diego
Joined Jul 2009
2,249 Posts
Quote:
Originally Posted by f82fan View Post
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.
bri6672 is offline Find More Posts by bri6672
Reply With Quote
Old Feb 18, 2013, 10:19 AM
Registered User
United Kingdom, Northern Ireland, Belfast
Joined Jun 2011
333 Posts
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!
Shane Sunday is offline Find More Posts by Shane Sunday
Reply With Quote
Old Feb 18, 2013, 01:30 PM
Hey Ya'll!! Watch THIS!!
Michael Paxton's Avatar
Nashville TN.
Joined Mar 2006
2,555 Posts
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.
Michael Paxton is offline Find More Posts by Michael Paxton
Reply With Quote
Old Feb 18, 2013, 01:39 PM
Registered User
Jetnfast's Avatar
United States, MO, Warrensburg
Joined Feb 2008
2,256 Posts
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.
Jetnfast is offline Find More Posts by Jetnfast
Reply With Quote
Old Feb 18, 2013, 05:02 PM
Senior Member
Arngeir Blakseth's Avatar
Molde, Norway
Joined Jan 2001
2,458 Posts
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.
Arngeir Blakseth is offline Find More Posts by Arngeir Blakseth
Reply With Quote
Old Feb 18, 2013, 07:31 PM
Registered User
bri6672's Avatar
San Diego
Joined Jul 2009
2,249 Posts
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!
bri6672 is offline Find More Posts by bri6672
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Build Log Fly-Fly F-4 Phantom: BUILD CRCJA Foamy EDFs 1937 Yesterday 02:31 AM
Sold Master Fly F-4 Phantom II 1/7 scale 99"lenth 65"w dhf23 Aircraft - Electric - Jets (FS/W) 9 Dec 29, 2011 09:43 PM
Alert E-Flite F-4 Phantom 32 DF ChuckTseeker Electric Plane Talk 17 Sep 09, 2011 12:54 AM
Discussion Starmax F-4 Phantom 90mm Build Thread neversommer Foamy EDFs 31 Jan 12, 2011 03:56 AM
Anyone build/fly AERC F-4 Phantom War Bird Radio Parkflyers 3 May 11, 2003 06:19 PM