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Seeking advice for my next Tiny Trainer

#1
Hi all,

I was delighted to find FliteTest a month or so ago, and have scratch built 5 planes over the past month or so, with intentions to continue to build more in the near future. I have been more focused on building than flying, and have no previous experience with RC. I used to enjoy building White Wings paper airplanes as a kid, and this feels like the natural extension of that pastime. I finally cobbled together the electronics needed to put one into the air, and figured the Tiny Trainer with non-aileron wings would be the place to start. My first take-away was that clearly RC flight was going to take some practice!

My main observation was that I could get it up 20' or so but by then it would begin rolling to the right, which also caused it to turn in that direction. Some judicious trimming of the rudder seemed to be enough to get it to steer it straight, but the roll continued until it was no longer stable (flying nearly sideways at times). So the best I could do was get it up into the air for a large loop and then back onto the ground before it got too sideways to handle in any way. I re-centered the wings after each "landing," so I don't think that the wings were merely off-center.

The good news is that it was a wet day and I was already intending to fly it to mechanical or water-log failure, and then rebuild it. I suspect my fusilage or tail fin(s) are skewed, but I am new to this so asking for confirmation on this or other suggestions that might make the trainer roll to one side without any ailerons in play. The couple of good hard "crashes" didn't damage the plane beyond scuffing the nose a bit and tearing loose the power pod, which I was able to replace on the spot and continue my flight attempts. All other landings were fairly graceful, but I was definitely impressed by the durability of the plane!

I have several other models built and have moved my electronics to an FT Long-EZ for my next flight, but hope to rebuild my Tiny Trainer soon and give it another try. I feel like it would have been fly-able, had I a means to adjust the tenancy to roll, so I'm looking forward to seeing what the "bank and yank" flying approach that the Long-EZ uses feels like vs. the Trainer.

A very cool experience to see the thing up in the air, even if it was for 30 seconds at a time at best! Looking forward to the rebuild and next flight. The plane itself is still intact, but the fuselage is definitely warped now from getting wet. Looking forward to the next build.
 

Merv

Well-known member
#2
Flying too slow can cause one wing to stall out, that is loose lift. You could also have build a twist into your wing. When you fold the wing, it's important to make the edges of the wing root even.
 

d8veh

Well-known member
#4
Before flying a new plane, you should check that there is no twist in the flying surfaces. You should be able to tell us that when you looked from the front, everything was straight. If it isn't, you need to adjust it. After you've switched on your radio gear, you should check again that all the moving surfaces are in the neutral position, unless you've deliberately set them off-centre to trim the plane for straight and level flight.

A plane like the Tiny Trainer needs a bit of side-thrust to counter the motor's torque. When viewed from behind the plane, if the direction of the propeller is clockwise, the torque will roll the plane to the left, so you need to point the motor a couple of degrees to the right to get neutral flight. You can adjust it by putting washers or other shims behind the motor. obviously, if your propeller turns the other way, the torque will be reversed and the side-thrust needs to be the other way too.

While you're dealing with side-thrust, you might as well add in the two degrees of down-thrust that will stop it from climbing steeply whenever you open the throttle. Another way to get these thrust adjustments is to make a new motor pod with the front shaved to the correct angles before gluing on the fire-wall.
 

FDS

Well-known member
#5
I had a bit of those symptoms, I just set a lot of expo on the ailerons on the 4 channel then left hand launched it, so I could correct with the ailerons and elevator as it leaves my hand.
The angle of the power pod can make a big difference to how the TT performs, I am on my 6th power pod already and have destroyed 2 firewalls as well.
When I have maiden’d the simple scout my son built I will tell you how that compares. I am not convinced the TT is the easiest FT design to fly, but haven’t flown enough different designs to prove it!
 
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Hai-Lee

Old and Bold RC PILOT
#6
The 3 channel wing is very easy to get what is effectively a twist in the wings id you are not extremely careful in making sure all of the joints and angles are set accurately. As a side note though I have actually built and flown the sport wing (Without ailerons) on a 3 channel setup and found that it actually performed quite well though a little faster than the polyhedral wing.

Keep at it and you will be flying like a pro in no time!

have fun!
 

Hai-Lee

Old and Bold RC PILOT
#9
I had a bit of those symptoms, I just set a lot of expo on the ailerons on the 4 channel then left hand launched it, so I could correct with the ailerons and elevator as it leaves my hand.
The angle of the power pod can make a big difference to how the TT performs, I am on my 6th power pod already and have destroyed 2 firewalls as well.
When I have maiden’d the simple scout my son built I will tell you how that compares. I am not convinced the TT is the easiest FT design to fly, but haven’t flown enough different designs to prove it!
Just something for you to check on! With the 4 channel wing it sometimes flies a lot better and if you like gentler with a minor increase in the wing incidence. Pack up the wing LE where it meets the fuselage so that the front of the wing is lifted by around a half to one millimetre.

The extra lift generated at a slower speed is very noticeable!

Have fun!
 

FDS

Well-known member
#10
I added a small incidence as suggested, didn’t really notice much difference. Will increase it a little more next time. It may be due to my ineptitude as a pilot.
 
#11
Thanks all for your input. The elevator is definately skewed a little, which looks subtle to my eyes but probably not to aerodynamics. My guess is that is the root of my problem, although I have not ruled out the glider wing yet, either. I'll try setting up the 4-channel wing and see how that flies, which may help me to rule out or confirm that my glider wing is wonky.

That said, it's true that my first instinct at the stick was to cut the engine as soon as I got a little uncomfortable with what I was seeing, something I'll need to train myself away from if I want to get these things up into the air more than 20' or so, which of course leaves very little room to save things before they hit the ground.

I'm currently building a mini guinea, and will then rebuild the fusilage on my trainer to try things out again. In the meantime, I have a Long-EZ built and ready to fly as soon as the rain lets up here. Thanks again for everyone's input and experience as I figure this out!
 

FDS

Well-known member
#12
I now keep climbing, compensating with the sticks until I get good and high, then if it’s a new set up, trim (Elevator, Ailerons, Rudder) whilst staying high, then see what’s what. If something is off then I drop the throttle and come in. I have also tried to stay off full throttle altogether, unless I really need to climb.
Staying high made a big difference to my flying experience with the TT. All the worst problems I have had were low to the ground.
Tell us how you get on with the Guinea, the full size one is in my build pile!
 

mayan

Well-known member
#13
I now keep climbing, compensating with the sticks until I get good and high, then if it’s a new set up, trim (Elevator, Ailerons, Rudder) whilst staying high, then see what’s what. If something is off then I drop the throttle and come in. I have also tried to stay off full throttle altogether, unless I really need to climb.
Staying high made a big difference to my flying experience with the TT. All the worst problems I have had were low to the ground.
Tell us how you get on with the Guinea, the full size one is in my build pile!
I try to keep throttle at 50% almost all the time. Helps me control the plane stress free.