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Help! FT Explorer - roll and nosedives with video

#1
Hi All - hoping to obtain some help. I purchased the speed build kit for the explorer at FliteFest for my son, but we can't get it to fly - we have several other planes that fly well, but can't keep this one in the air. I've tried making it nose and tail heavy, but the result always seems to be the same. Glide tests show it nose heavy even with CG way further back. I've also tried super low throttle all the way up to full throttle. Result is always the same - I need to pull up immediately after launching - it goes out a bit and then starts rolling and nosediving - I've had the plane go completly upside down. No rudder controls given to create the roll, plus we have the glider wing on, so it shouldn't roll. I can't perceive any twists in the wing nor tail, so I really don't understand the roll issue.

For the build - I went with normal 9g servos and the Turnigy D2836/8 motor with a 9x6 prop. Weight is 24.6 oz (685 grams).

- Sorry about my attire - I am dressed for working in the barn - not my YouTube de-beau
 

The Hangar

Well-known member
#2
Wow! I feel your pain - It took me forever to get my explorer to finally fly, due to a wrong thrust angle on the plans. speaking of thrust angle, is your thrust angle correct, and make sure your rudder is going the right way. This is all I can think of - hopefully you get it figured out. The explorer flies great though! Good luck!
 

The Hangar

Well-known member
#4
It looks like CG is right. What It looks like the plane is doing to me is that it is flying and then it is given full right rudder, but it looks like the tail didn't move and you said you gave no rudder input. Maybe try the sport wing so you have the extra channel to counteract the odd right bank/turn. I hope you get it figured out!
 
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Hai-Lee

Old and Bold RC PILOT
#5
It is hard to diagnose based upon the short video clip but I will hazard a few possibles which you can sort out or check.

Firstly what thrust angles are you using AND what direction is the prop rotating when viewed from the tail? If the motor has side thrust and the motor rotates in the wrong direction you will never be able to fly it with motor power!

Is the top centre panel of the wing, (between the folds), parallel with the wing bottom? If not and especially if the forward fold edge is lower than the rear fold edge, you have shifted the centre of lift rearwards and with it the required balance point.

When the motor is throttled up the plane has a tendency to squat or sag because the motor thrust angle has a downwards push on the airframe. If your plane has insufficient forward airspeed on launch it is possible to cause stall due to increased wing loading on throttle up.

If the wing incidence is poor and the plane a little heavy you can also cause a high speed stall or a nose dive on launch.

After checking the above you can try fitting a paddle pop stick or similar under the wing LE, ensure that you have no motor side thrust angle and try launching with a hard throw with the throttle at 50%. Slowly increase throttle only after the plane starts to climb!

Some pics and info can help to narrow the list of possible issues!

Have fun!
 

Chuppster

Well-known member
#6
From what I can tell the torque from the prop is what is driving it to the side. What happens if you counteract with opposite rudder?

I know with my Cub and Stearman, right after launch they will often "crab" on their sides, and even with ailerons they don't want to straighten out. I have to give rudder input to point the nose in the right direction.
 

Merv

Well-known member
#7
That is strange, it's hard to tell from the video, it almost looks like you plane is slowing down when you add throttle.
 

Piotrsko

Well-known member
#8
That's what I thought also but I'm old and therefore subject to hallucinations. However, my bronco did that on its maiden because the 50 year old radio I used is whacky. My response is #1 range test with motor running, #2 put plane on ground throttle up for a couple of seconds and see which way it moves. Motor has visible up thrust (correct for pushers above wing)
 
#11
Hi All - hoping to obtain some help. I purchased the speed build kit for the explorer at FliteFest for my son, but we can't get it to fly - we have several other planes that fly well, but can't keep this one in the air. I've tried making it nose and tail heavy, but the result always seems to be the same. Glide tests show it nose heavy even with CG way further back. I've also tried super low throttle all the way up to full throttle. Result is always the same - I need to pull up immediately after launching - it goes out a bit and then starts rolling and nosediving - I've had the plane go completly upside down. No rudder controls given to create the roll, plus we have the glider wing on, so it shouldn't roll. I can't perceive any twists in the wing nor tail, so I really don't understand the roll issue.

For the build - I went with normal 9g servos and the Turnigy D2836/8 motor with a 9x6 prop. Weight is 24.6 oz (685 grams).

- Sorry about my attire - I am dressed for working in the barn - not my YouTube de-beau
I'm thinking it's still to tail heavy and you my need full throttle to get it going. It's s best to have your planes more nose heavy for maiden flights... just my thoughts...
 

Headbang

Well-known member
#13
After frame by framing the video, it looks like there is right rudder. Could be an optical illusion. But it really does look like the plane rolls a little, maybe do to motor torque, and when you pull left the rudder is moving to the right making the situation worse. Could it be as simple as a reversed rudder channel? Also what direction is the motor spinning when looking at it from the rear? I assume ccw based on the way it rolled.
 

Hondo76251

Well-known member
#14
After frame by framing the video, it looks like there is right rudder. Could be an optical illusion. But it really does look like the plane rolls a little, maybe do to motor torque, and when you pull left the rudder is moving to the right making the situation worse. Could it be as simple as a reversed rudder channel? Also what direction is the motor spinning when looking at it from the rear? I assume ccw based on the way it rolled.
I tried slowing it down to see too, it does look like there could be some right rudder going on... but I can't tell for sure,
Another thing I did not notice before was your prop... looks suspiciously like it's on backwards, but again, hard to tell for sure. Make sure the lettering on the blade us facing the direction of flight. Could be the blade is pitched the right way but running in reverse...
 

Arcfyre

Well-known member
#15
Is the motor and prop spinning the right way? It almost looks like the prop is blowing air towards the nose, in which case it will never fly.
 

JTarmstr

Well-known member
#16
From what i can see, there wasn't enough power or airspeed to allow it to maintain flight. This resulted in the airplane rolling left and forcefully impacting with the ground. I dont know if you have tried to fly it since the video but have you attempted to launch at 100% throttle and threw it? I had a friend launch my FT Mustang for me and he threw it weakly and I tip stalled and crashed (throttle was at 75% on launch).

Also looking closely, the elevator seems to be deflected up highly. With low airspeed forcing the nose up will cause a stall. Hope this helps.
 
#17
Thanks for all the replies and sorry for the delay in replying. The prop is/was spinning correctly, however the only prop I had was a slowfly prop (9x4.7 i think), which might be the issue - too high of a KV for the slowfly causing weird torque issues? I have ordered and need to wait for a new prop - I ordered both an 8x4 and and 8x6 electric prop. If that doesn't solve it, I'll try to observe which way it's rolling on me and try to counteract with rudder trim. Postal service is saying Thursday arrival from the FT store - so I hope to do some testing then or the weekend (if my wife hasn't packed the schedule too full like last weekend). Motor angle was set based on the guide lines on the speed build kit - probably about 2-3 degrees down, and I no angle on the left to right axis.
 
#18
I FINALLY got a chance to get the new prop on that came probably 3 weeks ago. No real excuse other than not being totally convinced that a different prop would fix it. Anyway, put the new prop on last night after dark, and flew it tonight at dusk. It flew well - I didn't keep it in the air very long, because it's my son's plane, and I want him to have the most flight time on it. Hoping weather is decent tomorrow and I can get him in the air. Prop that caused problems was a TowerPro 9x6 slowfly, and the one that worked was a APC 8 x 6 pusher (had to reverse my motor). Model on the prop that worked was LP 08060EP.
 

The Hangar

Well-known member
#19
I FINALLY got a chance to get the new prop on that came probably 3 weeks ago. No real excuse other than not being totally convinced that a different prop would fix it. Anyway, put the new prop on last night after dark, and flew it tonight at dusk. It flew well - I didn't keep it in the air very long, because it's my son's plane, and I want him to have the most flight time on it. Hoping weather is decent tomorrow and I can get him in the air. Prop that caused problems was a TowerPro 9x6 slowfly, and the one that worked was a APC 8 x 6 pusher (had to reverse my motor). Model on the prop that worked was LP 08060EP.
Glad you got it to work!