Flight Times

[illusionist]

[quote="jcollier"]IME, .093-.062 would be too drastic of a change. Our planes fly well with .080 to .085 rubber. If you are pressed for time and can't get thinner rubber, you could always decrease the wing incidence (angle of attack) a mm or so and see what that does.[/quote
As of right now, I actually don't have any wing incidence. My tail boom is set at an upwards angle compared to the motor stick. The wing lies flat on the motor stick.

[goblue007]

Are their any ways to keep a plane from climbing so fast?

[SOCoach]

My girls flew their plan at Regionals this past weekend at got a time of 2:28. The plane weights 7.3 grams and they were using .083 rubber. The are asking me two questions that I cannot answer . . . which is why I came here! One, what were the times at State (Michigan) last year and would 2:28 be competitive and Two, is there anything short of making a new plane, they can do to get better times?

Okay . . . that is actually three questions, but you get my point

[jcollier]

SO coach:

2:28 is certainly a respectable time. Michigan is a pretty competitive state though. Jeff Anderson could tell you more about last year's times, but I remember them being pretty good. Things can happen when teams go too aggressive on flight one, as my son found out at regionals this year. A good consistent effort can medal, because you have to fly a good time on one of 2 attempts in competition.

That said, the .3 grams you are over doesn't help, but a good flying plane of that weight can fly pretty decent times. Still, my other WS flyer, an 8th grader, laid up a very nice stabilizer in about 30 min. or less today. A wing and stab can be made and covered in a few days at most if the kids are motivated. The main thing is to build carefully with good wood. How much time do you have until States?

[calgoddard]

Are their any ways to keep a plane from climbing so fast?

See Jeff Anderson's post quoted above.

The goal of Wright Stuff is a slow climb to just below the ceiling, a long cruise (four or five circles without gaining or losing altitude) and a slow descent, with the plane landing with 50 turns or so. Landing with NO turns is bad. Once you get below 50 turns the torque is so minimal that descent is too rapid.

You need to match rubber width to prop for the air frame, with lots of test flights, and you need to optimize the decalage . i.e. the relative angle of attack of the main wing to the angle of attack of the stab.

Keep detailed flight logs, change one variable at a time, and stay away from basketballs.

I can't tell you if a specified rubber width is too big or too small unless I know the diameter of the propeller, the blade profile and the pitch of the propeller. Then I still need to know the number of winds at launch, turns backed off, the torque at launch, the max height of the flight and the number of turns remaining on landing, and of course, the duration of the flight. Then I still need to see a flight log with lots of flights with different rubber widths, turns and torques,etc. I really need to see the plane in flight so I can evaluate the trim. This is why if you are going to medal at Nationals you need to hook up with an experienced mentor, who can show you what all these things mean. I can almost gurantee that the gold medalist in Wright Stuff at the 2010 Nationals will have had the benefit of the coaching of such a mentor.

Someone should break five minutes at Nationals this year if they build the right plane and test with partial motors. I prefer the 2010 Cezar Banks design, although the 2010 Ziegler design is fine because he eliminated that wire between the motor stick and the tail boom. Our team always built custom planes after the first few years as they were cheaper and we could make them look different. The students could also select the best wood.

[SOCoach]

We have nearly 6 weeks until the State Competition so I will recommend to my girls to try and get the weight down a bit more. I think we will also experiment with .079 rubber and see what we can do with that.

Thanks!

[jander14indoor]

My girls flew their plan at Regionals this past weekend at got a time of 2:28. The plane weights 7.3 grams and they were using .083 rubber. The are asking me two questions that I cannot answer . . . which is why I came here! One, what were the times at State (Michigan) last year and would 2:28 be competitive and Two, is there anything short of making a new plane, they can do to get better times?

Okay . . . that is actually three questions, but you get my point

2:28 is a good, respectable time at Michigan. It would win some years, not others. Should certainly medal. The gym at MSU is on the low side, only 25 ft or so, but lots of floor space. So trim for low ceilings and open turns. Not too open, there is some drift depending on time of day in that room, but you don't need a 20 foot circle either.

Others (and my past notes) have answered your other questions.

Jeff Anderson
Livonia, MI

[illusionist]

Based on my plane that has a 38.5 cm wingspan and 11 cm chord, 19 cm stabilizer span, 6 cm stab chord, 3/32 inch rubber motor, and a 20 cm ikra prop and weighs exactly 7.1 grams. If I increase the area of the stabilizer, will I need to adjust the size of my wing? I know I will have to do some re-trimming though.

[illusionist]

Quick question, how should I adjust the center of gravity? Adding wire or other mass is adding a little too much weight...

[sciolyandmathcounts]

Blah, our school got 2:56 and we missed getting first because of Thomas Jefferson, who got 2:57! I'm not in Wright Stuff, but still..........