Wright Stuff C

Locked
lechassin
Member
Member
Posts: 187
Joined: September 11th, 2019, 9:49 am
Has thanked: 0
Been thanked: 0

Re: Wright Stuff C

Post by lechassin »

OpticsNerd wrote: December 10th, 2019, 10:28 am I'm having an issue right now. So when I fly with right turns my plane stalls with high torque but then slowly transitions to a dive over about 30 seconds as the torque decreases. The strange part is that this only happens with right circles; it actually flies very nicely with left circles. I've tried adjusting the shim to change the twist of the wing and changing the angle of the rudder to change the circle radius but neither fixed the problem. I'm also 95% sure nothing is moving by a significant amount during the flight. If anyone has any ideas please tell me. I really can't afford to continue having the right turns hinder my performance at competitions.
Once we have a decent flying plane, we do the fine-tuning in the same order every time we change something: first tweak the CG to achieve nice recoveries (HVAC or touches), then set the rudder to get a good radius, then tweak decalage to get a flat cruise. We do that with partial winding to speed up the process. Don't hesitate to fly right and left with different decalage settings. I recommend the decalage all be in the wing, keep the stab neutral; this creates a down thrust effect that helps control launch angle (you can add actual down-thrust, we have not). Only after we have a nice cruise do we worry about the launch.

To the left, we never had much problem: higher launch torque just makes the plane bank steeper at first, which controls the climb angle semi-automatically. You may be experiencing a similar thing.

To the right, we had the same problem as you. Compare these videos from early and recent flights. In each of these videos the cruise is nice and you can clearly see the launch evolve; again, we make sure we have a good cruise before working on the launch:
https://www.youtube.com/watch?v=u77yWYz5yow this launch doesn't stall but it also doesn't climb high enough. We kept the launch from stalling by launching at low torque, so fewer knots/less power, ergo shorter flight time, not ideal.
https://www.youtube.com/watch?v=gIZRCyUUGVY&t=34s higher launch torque, we're getting good height and better times, but now the launch is a concerning affair. I predict this is what your plane will do once you get the cruise to stay flat.
https://www.youtube.com/watch?v=yju4a7rvPm8 this one's perfect. I especially like this flight because it confirmed the effect of the rudder. In this case we had too much: just prior to this flight I launched the plane into a slow descent. I intercepted it right away, decreased the rudder a little, and tossed the plane again into what has remained our best setting. If it had launched into a stall, I would have increased the rudder. It doesn't bank much going to the right, so I think the rudder is affecting the amount of side slip. I'm really not sure why, but it works perfectly for us. Interestingly, the rudder adjustments at this point are tiny and the cruise radius doesn't change.

Sadly though, there's still a lot of fiddling; an improvement in launch often causes a problem in cruise, or vice-versa. One thing that's a total freebie is a flaring prop]. The plane won't pull away as steeply when you launch at higher torques, and cruise won't change at all. I think this year's planes really need that to launch well and get good height.
bjt4888
Member
Member
Posts: 843
Joined: June 16th, 2013, 12:35 pm
Division: C
State: MI
Has thanked: 0
Been thanked: 44 times

Re: Wright Stuff C

Post by bjt4888 »

lechassin wrote: December 10th, 2019, 3:02 pm
OpticsNerd wrote: December 10th, 2019, 10:28 am I'm having an issue right now. So when I fly with right turns my plane stalls with high torque but then slowly transitions to a dive over about 30 seconds as the torque decreases. The strange part is that this only happens with right circles; it actually flies very nicely with left circles. I've tried adjusting the shim to change the twist of the wing and changing the angle of the rudder to change the circle radius but neither fixed the problem. I'm also 95% sure nothing is moving by a significant amount during the flight. If anyone has any ideas please tell me. I really can't afford to continue having the right turns hinder my performance at competitions.
Once we have a decent flying plane, we do the fine-tuning in the same order every time we change something: first tweak the CG to achieve nice recoveries (HVAC or touches), then set the rudder to get a good radius, then tweak decalage to get a flat cruise. We do that with partial winding to speed up the process. Don't hesitate to fly right and left with different decalage settings. I recommend the decalage all be in the wing, keep the stab neutral; this creates a down thrust effect that helps control launch angle (you can add actual down-thrust, we have not). Only after we have a nice cruise do we worry about the launch.

To the left, we never had much problem: higher launch torque just makes the plane bank steeper at first, which controls the climb angle semi-automatically. You may be experiencing a similar thing.

To the right, we had the same problem as you. Compare these videos from early and recent flights. In each of these videos the cruise is nice and you can clearly see the launch evolve; again, we make sure we have a good cruise before working on the launch:
https://www.youtube.com/watch?v=u77yWYz5yow this launch doesn't stall but it also doesn't climb high enough. We kept the launch from stalling by launching at low torque, so fewer knots/less power, ergo shorter flight time, not ideal.
https://www.youtube.com/watch?v=gIZRCyUUGVY&t=34s higher launch torque, we're getting good height and better times, but now the launch is a concerning affair. I predict this is what your plane will do once you get the cruise to stay flat.
https://www.youtube.com/watch?v=yju4a7rvPm8 this one's perfect. I especially like this flight because it confirmed the effect of the rudder. In this case we had too much: just prior to this flight I launched the plane into a slow descent. I intercepted it right away, decreased the rudder a little, and tossed the plane again into what has remained our best setting. If it had launched into a stall, I would have increased the rudder. It doesn't bank much going to the right, so I think the rudder is affecting the amount of side slip. I'm really not sure why, but it works perfectly for us. Interestingly, the rudder adjustments at this point are tiny and the cruise radius doesn't change.

Sadly though, there's still a lot of fiddling; an improvement in launch often causes a problem in cruise, or vice-versa. One thing that's a total freebie is a flaring prop]. The plane won't pull away as steeply when you launch at higher torques, and cruise won't change at all. I think this year's planes really need that to launch well and get good height.
Yes, as noted by Eric, rudder causes both yaw and roll and this trim can be used to good advantage in controlling initial climb. See attached interesting discussion and chapter from Aero text:

https://physics.stackexchange.com/quest ... is-applied

Sorry to be out of communication recently. Getting three teams ready for their first Invitational this weekend has been time-consuming. Teams are at about 120 test flights so far and learned a lot. Forum comments and assistance from Jeff, Eric, Calgoddard, Coach Chuck and others have been very good.

Brian T
CrispyFern
Member
Member
Posts: 5
Joined: September 19th, 2019, 4:53 am
Division: C
State: IN
Has thanked: 0
Been thanked: 0

Re: Wright Stuff C

Post by CrispyFern »

I’m struggling to push past around 60 seconds in both directions. I think everything is trimmed pretty well but my motors might be the problem. They are pretty thick ~.12 and fly at around 2500 turns and .5 in oz of torque. The motor is at 5-10 winds when my plane lands. I’ve seen a lot of talk about thinner motors as lower torque. Should I start to focus on how I make my motors to improve? Am I correct in thinking that thinner motors will allow for more winds but lower torques?
bjt4888
Member
Member
Posts: 843
Joined: June 16th, 2013, 12:35 pm
Division: C
State: MI
Has thanked: 0
Been thanked: 44 times

Re: Wright Stuff C

Post by bjt4888 »

CrispyFern wrote: December 12th, 2019, 5:29 am I’m struggling to push past around 60 seconds in both directions. I think everything is trimmed pretty well but my motors might be the problem. They are pretty thick ~.12 and fly at around 2500 turns and .5 in oz of torque. The motor is at 5-10 winds when my plane lands. I’ve seen a lot of talk about thinner motors as lower torque. Should I start to focus on how I make my motors to improve? Am I correct in thinking that thinner motors will allow for more winds but lower torques?

CF,

Your thinking in the right direction. Once you have basic trim and stable flight, a significant piece of the science of the project is testing many variations in rubber density (thickness of rubber is not accurately measurable) and length and propeller design and pitch.

Also, you did not mention backoff winding. You will advance rapidly in the project if you take an hour and read all previous posts in this forum. And, you will advance even more if you read all posts in the previous year and in 2015 and 2016 for Wright Stuff. This is the scientific research part of the project.

Have fun,

Brian T
User avatar
xiangyu
Member
Member
Posts: 276
Joined: April 6th, 2019, 8:32 pm
Division: Grad
State: MI
Pronouns: He/Him/His
Has thanked: 7 times
Been thanked: 6 times

Re: Wright Stuff C

Post by xiangyu »

My first Invitational is this Saturday! Wish me luck lol. :lol:

I'll let you guys know how it goes!

Xiangyu
Medal & Ribbon Count: 33
Former EGRHS Team Captain 2017-2021
https://scioly.org/wiki/index.php/User:Xiangyu
bjt4888
Member
Member
Posts: 843
Joined: June 16th, 2013, 12:35 pm
Division: C
State: MI
Has thanked: 0
Been thanked: 44 times

Re: Wright Stuff C

Post by bjt4888 »

Xiangyu,

Best of luck. Fly well.

My teams are in competition with you, but I truly want everyone to do their best and have fun.

Brian T
User avatar
xiangyu
Member
Member
Posts: 276
Joined: April 6th, 2019, 8:32 pm
Division: Grad
State: MI
Pronouns: He/Him/His
Has thanked: 7 times
Been thanked: 6 times

Re: Wright Stuff C

Post by xiangyu »

bjt4888 wrote: December 12th, 2019, 10:10 am Xiangyu,

Best of luck. Fly well.

My teams are in competition with you, but I truly want everyone to do their best and have fun.

Brian T
Thanks! Good luck to your teams, too! I look forward to watching them fly!

Xiangyu
Medal & Ribbon Count: 33
Former EGRHS Team Captain 2017-2021
https://scioly.org/wiki/index.php/User:Xiangyu
newflight
Member
Member
Posts: 34
Joined: February 2nd, 2019, 8:48 pm
Has thanked: 0
Been thanked: 0

Re: Wright Stuff C

Post by newflight »

where are you competing this weekend?
xiangyu wrote: December 12th, 2019, 10:21 am
bjt4888 wrote: December 12th, 2019, 10:10 am Xiangyu,

Best of luck. Fly well.

My teams are in competition with you, but I truly want everyone to do their best and have fun.

Brian T
Thanks! Good luck to your teams, too! I look forward to watching them fly!

Xiangyu
User avatar
xiangyu
Member
Member
Posts: 276
Joined: April 6th, 2019, 8:32 pm
Division: Grad
State: MI
Pronouns: He/Him/His
Has thanked: 7 times
Been thanked: 6 times

Re: Wright Stuff C

Post by xiangyu »

newflight wrote: December 12th, 2019, 8:28 pm where are you competing this weekend?
Portage Northern
Medal & Ribbon Count: 33
Former EGRHS Team Captain 2017-2021
https://scioly.org/wiki/index.php/User:Xiangyu
User avatar
vehicleguy
Member
Member
Posts: 157
Joined: April 7th, 2017, 4:13 pm
Division: C
Has thanked: 11 times
Been thanked: 13 times

Re: Wright Stuff C

Post by vehicleguy »

I'm having trouble getting my mylar to not be wrinkled. I heard of blowing a hair dryer over it, but are there better solutions?
By the way, I also make sure to always crinkle it up before attaching it to the wing.
AHHS '22 Vanderbilt '26
2022 Events: Chem Lab, Envi Chem, It's About Time, Orni, PPP, Wright Stuff
2022 States: 3rd Envi Chem, 3rd Orni, 4th Wright Stuff
Userpage- https://scioly.org/wiki/index.php/User:Vehicleguy
Locked

Return to “Wright Stuff C”

Who is online

Users browsing this forum: No registered users and 1 guest