Design

[nxtscholar]

Maybe helpful or not, but what I've found from test gliding is that if your plane tends to glide to the left, sometimes it's because of a weight imbalance. From the pilot's perspective, the right side would be somehow heavier (in my case, I spray painted too much, so now I just use colored tissue paper instead).

It is important to note that a plane can still fly in a left-hand circle without stalls or any initial problems upon an actual launch even if it test glides to the right. Although, not going to get optimal flight times.

[InfiniCuber]

Maybe helpful or not, but what I've found from test gliding is that if your plane tends to glide to the left, sometimes it's because of a weight imbalance. From the pilot's perspective, the right side would be somehow heavier (in my case, I spray painted too much, so now I just use colored tissue paper instead).

It is important to note that a plane can still fly in a left-hand circle without stalls or any initial problems upon an actual launch even if it test glides to the right. Although, not going to get optimal flight times.

How would I go about changing which direction it turns?

[retired1]

Several things will affect the turn. There is nothing that says that it has to turn left, it is just a bit more efficient if it does.
The leading edge of the left wing should be a tiny bit higher than the right OR the right wing leading edge should be a bit lower--this allows for a level flight. In your case, you probably have too much. Check this first.
Then look at your front motor mount. it should be about 3 degrees to the left. 5 is not terrible but not great.
Is your rudder rear edge about 1/16" to the left of the leading edge of the rudder?
Is the right side of your horizontal stabilizer about 3/8" lower than the left?
Is your tail boom cocked or warped a bit to the left? If not, this is an easy fix to warp it with your fingers. About 1/8" + or-.

[bjt4888]

InfiniCuber,
If your only basic change was a new wing, which resulted in extreme stalling and right turn instead of left, your issue is most likely with your wing. I would suspect too much incidence (LE higher than TE). Many of these airplanes will fly well with less than 1.5 degrees of total decalage. So, if your tailboom is angled so that the tip of the boom is 1/8" higher than the attach point at the motor stick,it has 0.6 degrees of negative incidence and the wing will only need about 1.0 degrees of positive incidence to reach a total decalage angle of 1.6 degrees (see how that works, it's the difference between the stab and wing incidence angles). 1.0 degrees of wing incidence is the wing leading edge about 1/16" higher (greater distance from the top edge of the motor stick) than the trailing edge.

Many of the airplanes will fly well with as little as 1/16" of left wing washin (left wing leading edge 1/16' higher than the trailing edge. You should develop the ability to eyeball this (remember most TE's are 1/16" thick, so if you can align the right wing so that it appears perfectly flat, then you should be able to see the left wing TE hanging just below the leading edge; as viewed from the front of the airplane). I am thinking that you need to reduce your left wing washin (or, if your left wing is flat and your right wing is washed-out, reduce the right wing washout for the same effect).

Retired1 gave you good advice for other left turn settings. The Freedom Flight airplane design indicated 3/8" of tailboom offset, 1/8" rudder offset and 3/8" of stabilizer tilt (measured from the middle of the stab to one stab tip). Your V-dihedral designs may require more tailboom offset. I've used as much as 5/8" in some cases for similar models.

Here's a quick photo of two more sets of flying surfaces on the covering frames that my students assembled today.

Brian T.

[Less_Incidence]

I'm fairly new to flight-related events in SciOly (Placed 2nd in State ELG C last year, first time I'd competed in a flying event). I have a fairly good design and a well-built plane, but no matter what I try as far as trimming I am stuck in this 2:45 rut. I haven't had a single flight above 2:50, and I know that I likely won't medal in my state below 3:00.

After reading this discussion I was thinking quite seriously about a torque burner, but how do these mechanically work? I've found almost no information on them in the vast expanses of the internet, outside of the general concept of what they are.

The torque burner design idea I've had so far is a rubber O-ring around the motor, with a string attached to that O-ring running across a couple of pieces of wire acting as pulleys, then connecting to a clip which tightly holds the middle of the motor (Maybe closer to 60 percent of the way back between the prop and the motor hook) until the front part of the motor unwinds enough for the clip to come undone (Torsion in rubber lessens ergo force on O-ring lessens ergo string tension lessens ergo clip loosens). However, I am convinced there is a much simpler way to do this and am envisioning a whole host of problems with the aforementioned O-ring around the motor.

Is anyone more familiar with torque burners (I'm looking at you, torqueburner) or their design?

[InfiniCuber]

Several things will affect the turn. There is nothing that says that it has to turn left, it is just a bit more efficient if it does.
The leading edge of the left wing should be a tiny bit higher than the right OR the right wing leading edge should be a bit lower--this allows for a level flight. In your case, you probably have too much. Check this first.
Then look at your front motor mount. it should be about 3 degrees to the left. 5 is not terrible but not great.
Is your rudder rear edge about 1/16" to the left of the leading edge of the rudder?
Is the right side of your horizontal stabilizer about 3/8" lower than the left?
Is your tail boom butterfly or warped a bit to the left? If not, this is an easy fix to warp it with your fingers. About 1/8" + or-.

Thank you, this is very helpful. I think the things you pointed out are my problems, so time to fix!

InfiniCuber,
If your only basic change was a new wing, which resulted in extreme stalling and right turn instead of left, your issue is most likely with your wing. I would suspect too much incidence (LE higher than TE). Many of these airplanes will fly well with less than 1.5 degrees of total decalage. So, if your tailboom is angled so that the tip of the boom is 1/8" higher than the attach point at the motor stick,it has 0.6 degrees of negative incidence and the wing will only need about 1.0 degrees of positive incidence to reach a total decalage angle of 1.6 degrees (see how that works, it's the difference between the stab and wing incidence angles). 1.0 degrees of wing incidence is the wing leading edge about 1/16" higher (greater distance from the top edge of the motor stick) than the trailing edge.

Many of the airplanes will fly well with as little as 1/16" of left wing washin (left wing leading edge 1/16' higher than the trailing edge. You should develop the ability to eyeball this (remember most TE's are 1/16" thick, so if you can align the right wing so that it appears perfectly flat, then you should be able to see the left wing TE hanging just below the leading edge; as viewed from the front of the airplane). I am thinking that you need to reduce your left wing washin (or, if your left wing is flat and your right wing is washed-out, reduce the right wing washout for the same effect).

Retired1 gave you good advice for other left turn settings. The Freedom Flight airplane design indicated 3/8" of tailboom offset, 1/8" rudder offset and 3/8" of stabilizer tilt (measured from the middle of the stab to one stab tip). Your V-dihedral designs may require more tailboom offset. I've used as much as 5/8" in some cases for similar models.

Here's a quick photo of two more sets of flying surfaces on the covering frames that my students assembled today.

Brian T.

Very helpful. I didn't even think about this but I will definitely try it. Esp due to my v-dihedral, thank you!

[nxtscholar]

@Less_Incidence: well, I guess I had more luck than you then, finding something in "the vast expanses of the internet."

imho at the very least, there is a simpler way to go about the torque burner concept consisting of simply wire. Check your PM.

Perhaps you already know, but aside from investing a large amount of time into it, do note that it is extremely important that you use a torque burner only at low sites. At high sites, it's actually harmful to flight times to not let your plane climb to the maximum altitude.

[jander14indoor]

At 2:30 plus times (you don't mention ceiling height) you are already a very good flier. Besides torque burner (if you are in a low site, say 25 ft or so) you need to start looking at sources of drag and really optimizing things. Perhaps play with prop designs. Different prop/rubber combos.

Good job
Jeff Anderson
Livonia, MI

[Less_Incidence]

Thanks for the help everyone.

I did some bench testing of the torque burner and very quickly got the impression that it is extremely hard to optimize and know exactly where to place the tube, what length to cut the tube/wire to, et cetera... I decided it probably won't be practical for me this year. Maybe next time.

My next thought is to use the Ikara flaring propeller, but I read earlier in this thread about them being trimmed/sanded and also found elsewhere that the prop has to be trimmed to fly properly. Is there a particular plan that shows a good way to trim/adjust the prop, and is there any particular technique to sanding or cutting it?

[jander14indoor]

Exactly the issue with torque burner. Not allowed in AMA competition so not a lot of experience/data. The student who did it successfully had been flying four years and didn't do it until he was already VERY competitive. He felt it was worth his time because at the Michigan State tournament in those years we flew in a fairly low site, about 18 ft at the edges and 24 in the center. He went from competitive and likely to win the tournament to blowing folks away. But it took a LOT of his time.

Jeff Anderson