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Newbie to RC with TT CG probs

#1
So I built the Tiny Trainer a couple of weeks ago and I've been crashing it ever since. It veers left on launch and wants to cartwheel into the dirt. I noticed that the CG is where marked with NO Battery. I've read a few threads with the same complaint. I've also read that launching with throttle will cause it to veer left. I'm hoping that moving the battery back will help it to fly better. I'm currently heavily modding it so I can place the battery under the wing but this will require me to move the servos back closer to the tail. I don't mind doing the work, but is all this really necessary?
Thanks,
 

BATTLEAXE

Well-known member
#2
Hello Just Mike and welcome to the forums. I too had issues with the TT. It was a fickle little beast for me to get in the air. I made two of them just in case I did something wrong with the first one. The first one was just like what you have, stock. The second had a few mods like moving the tail servos back to make room in the fuse for other electronics and battery etc. I still had issues with it but some here swear by that plane.

Some questions for ya...

What size of motor?
What size of prop?
What size is the battery?
Do you have any video of these attempted launches?

The video thing will really go a long way to helping us diagnosing the problem. But from what you described it sound like you are having a torque roll issue. What's happening is that there isn't enough speed on the launch for the wing to take effect and stabilize the roll caused by the spinning prop. Being somewhat tail heavy can be a factor as well. I imagine this is your first plane so I am guessing you set it up as a 3 channel rudder/elevator/throttle system? The CG is an all up weight mark, meaning the battery as well. This is because everyone uses a different battery so there is no way to account for that from the mark of suggested CG. So if this is a balance issue then resetting your gear locations so your CG is a bit nose heavy with all the gear in is ideal. Other then that try to start with a little right trim in the rudder, just a few clicks right from center should be fine. This ideally should compensate for the heavy left roll. Beyond that you could look into if the wing has twist in it, could have happened while building it. If your tail feathers are square to the rest of the plane like the wing etc.

Keep us posted
 

Hai-Lee

Old and Bold RC PILOT
#3
The swerving to the left on launch sounds like a thrust angle issue. I have built many over the years and the power pod has the required side thrust angle built in on one end. If you fitted the firewall on the wrong end of the power pod then the plane will always veer to the left. When assembled the motor should point slightly to the starboard side of the plane, (for a CCW motor installation. If the motor shaft is pointing straight ahead or to the port side then the powerpod is assembled or fitted incorrectly.

There are a myriad of other possible build issues that you need to check but the powerpod and motor installation are of primary importance.The CG point or balance point is approximately 25% of the wing cord back from the wing Leading Edge. I have flown them very nose heavy and even quite tail heavy with a little difficulty. At 25% of the cord the TT should fly almost perfectly straight and almost directly out of your hand!

A pic or two of your build would help and a video of your flight attempts would be solid gold in diagnosing any further issues.

Have fun!
 
#4
Thanks guys. I ordered it with power pack A which includes a radial 1806 2280kV motor and 6/3 props.
Dont think I have any way of recording so I'll rely on your advice and keep reading!
 

Hondo76251

Well-known member
#5
+1 on the thrust angle. I had previously read some of the issues people had experienced with the TT so the first time I built a powered one I added a pretty significant down and right thrust angle. It was bone stock other than that and it flew great. It was a bit nose heavy but thats usually not too big of a deal. I've built several since pretty much as per the instructuons with a touch more thrust angle and I've always seemed to have good luck.
 
#6
I confirmed that the thrust angle is correct. In fact I rebuilt the power pod so it's like new. I also shortened the control rods and moved the servos back so I could put the battery under the C.G. it balances perfectly now.
 
#9
Which is the right direction? I gotta assume it is since I have standard props that came with the kit and it's pulling the plane. I don't think it would fly at all if it were spinning backward. Don't have it in front of me but i believe the correct direction is CCW when facing me.
 

Merv

Well-known member
#10
At FF19 I shared the build table with 3 noobs who all built the TT from a kit. When it was time, I was given the privilege to maiden all 3. All 3 were balance at the CG mark on the kit, they all flew tail heavy. When we moved the CG forward 1/4 inch from the mark, all 3 planes flew great.

Try making the plane balance 1/4 inch forward of the CG mark.