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FT Flyer Unpredictable Nose Dives??

ttrando

Junior Member
#1
Hey guys, I'm relatively new to RC and I've had quit a few experiences with planes crashing. However, I've never had a problem like this one. My friend and I build him a FT Flyer. Looks great and construction seems to be very sound.(will post pics if needed.)
However we popped the electronics in the swapable fuselage and tried to maiden it. It would fly true for several seconds and then all of a sudden it would plunge into a violent nosedive. It is properly trimmed and flies level, but has a tendencies to dive randomly without user input. Checked everything and I can't detect the issue.
I figure it could 1 of 2 things.
1) Perhaps the radio is glitching from interference causing the servo to twitch? It is DSM2 only
2) The elevator servo is broken and moves unpredictably.

However I have not seen any of these issue in preflight and it has no other bad tendencies. I will further dissect this issue with field testing, but it looks like it may be a very hard mystery to uncover. My FT Flyer is unbeleivabley versatile, and I dont't understand why this one is so unpredictable. Hopefully this is a basic beginner issue that you can set me straight on. Thanks in advance for your superior knowledge

Plane Specs.
1x Park300 1600kv motor
1x 18A Plush Speed Controller
2x HXT900 9g servos
1x Turnigy 500mAh 3s Lipo
1x Orange 6ch Rx w/o failsafe
1x T-SIX 6ch Orange Transmitter(DSM2)
 
#3
I actually had this problem with the one I built 2 days ago. I didn't figure out what caused it yet. It needs some pretty extensive repair. The firewall broke and the front skewers that hold the pod ripped out of the air frame taking a decent chunk of foam with it. Mine was within 20 yards of me when it happened.
 

ttrando

Junior Member
#5
Earth- I did neglect to perform a range check. I will try this later. However, I've had this happen off of launch, distance of a few meters. Thanks
Shadow- It looks like we can have a fun time figuring out this phenomenon together. Good luck with repairs. They might be a pain, but at least they are dirt cheap.
Colorex- I am almost certain this was not caused by a stall. Th Flyer has extremely forgiving stall, and a low stall speed. Unless there is something very aerodynamically wrong with my friend's (which looks unlikely), I do not see how this could have been a stall. For what its worth, I've almost hovered this thing without it diving, but sometimes at more normal speeds it goes straight down. I believe speed is irrelevant.
 

colorex

Rotor Riot!
Mentor
#6
If you run the motor and move stuff around, do you get glitches in the elevator? Wiggle the cables around and see if the elevator stays true.
 

pgerts

Old age member
Mentor
#7
Toss and fly inverted - if it goes up instead of down you might be sure that the problem is in the electronics.
 

ttrando

Junior Member
#8
I have pretty much eliminated the radio as an area of fault. Swapped his orange system out with my 6ch dsmx system and still got poor results. It did fly straight and level for about 30 seconds at one point, a new record. I will continue to check the electronics. I recently experienced issues with hxt900 servos locking up in my simple f22, so servos will be a good place to look for error. As far as inverted goes, it's a great idea, but we'll see how long I can keep a functional Flyer inverted. It has a tendency to roll upright due to its large wing surface area and dihedral. The motor mount came of the firewall in today's tests. It would have much earlier if it weren't for the advantageously high grass where we fly. I appreciate all the help. Please keep throwing m ideas.
 
#9
Does the plane recover from the dive? If so, by itself or with controller input? How do the elevator hinges look? What sort of material did you use for control horns and rods? Any wobble there? What's the weather like? Are there any funky spots in the servo wires? Are all the connections secure? Is it difficult to plug the battery in? Is the battery really secure? It took me forever to realise the battery in my Catalina was sliding rearward because it would slide back into place during landing.

Take the plane up really high and glide for a bit. Will it glide hands off? Do you have to point nose down, or up to glide?

Does it do this only when your friend is at the controls?

My wife had an F-117 that would do the same thing. It turned out to be a combination of too far forward cg and high stall speed. It flew OK at lower speeds, but only if it stayed level. Any bit of nose up attitude below 1/2 throttle and it would go all kamakazi.

A way to test connections is to power up the plane and shake, roll, swing it around, drop and catch, and slap it. Just because it works on the ground doesn't mean it will in the air.
 

ttrando

Junior Member
#10
The plane recovers from dives usually with a lot of down stick. The rods are steel cable and the horns are plastic. They are both secured well. The weather is decent, not enough wind to throw the plane around. The battery is secure and I will check over all the electronics. I will attempt to gain enough altitude to do a glide test, but the Flyer has an inherently poor glide slope. I have yet to stress test it on the ground, that will go with examining linkages and wires. I have a feeling it may be a weird quirk related to the cg but the fact that it flies alright sometimes make me feel like it might not be. I will inspect that as well. And yes I am sure it is the plane, not the pilot(completely);) Thanks for the input guys. Keep it coming if you will and I'll try to do some tests tomorrow afternoon. Weather permitting.
 
#12
The similar problems I've had with mine is a faulty HXT500 servo and, as a result, a loose rudder horn. Easy to check both on the ground... Other than that - nasty winds or bad cg. Checked the failsafe input setting?
 

ttrando

Junior Member
#13
See, the orange rx I have lacks failsafe and I originally thought that might be the issue, but I confirmed that the radio system is irrelevant. I will try replacing servos. Many thanks.
 

Enjaa

Junior Member
#14
My 13 year old son was flying his Flyer and was getting the same nose dive issues. I just thought he was causing it and didn't think much about it until we had to build new Flyers because the our planes were tore up from dog fighting. What a blast! But, now my new plane is doing the exact same thing. The plane will be flying along and it does a right angle dive at the ground. I've checked CG, electronics...... But nothing. It's unnerving not knowing when it's going to happen. Anybody figure this out?
 

Enjaa

Junior Member
#16
Thanks Randall. Can a plane be tail heavy even though the CG is good? I'm flying it with a 1300 lipo that is midway back on the plane to make CG.
 
#17
I had an airplane similar to the FT Flyer that would do the same thing. It was caused by a binding elevator. If I gave it a little down elevator it was fine for a second but it would suddenly pop into full down. The stabalizer being slightly warped caused this reaction. It's a long shot but this could be your problem?
 
#18
I agree with those who suggest binding or slack in the controls. If cg was off, it wouldn't fly fine for 30 seconds. I have a foamie that started flying erratically. Turned out that one of the servos was just lose enough that it would lever itself out of alignment instead of moving the elevator.

Good luck!
 
#19
Well again my first theory would be a manhandled cheap servo acting up, or a loose rudder horn, something like that... or a brownout of some kind.

To reproduce it do some "dry runs" on the ground, where one of you holds it and watches what happens while the other one controls it while narrating what should be happening.
 

Enjaa

Junior Member
#20
Tail heavy! I took a better look at CG and was slightly back for the Flyer, so I moved the battery up towards the nose about two inches and haven't had the problem since.