Humidity
Posted: April 4th, 2010, 2:47 pm
StampingKid:
You have raised one of the most difficult issues with Wright Stuff. After years of coaching Wright Stuff I eventually realized a major problem but could not get an adequate answer, even from experts with 50 years of indoor rubber powered flying experience.
Here is the problem. You practice for weeks or months in your gym, much of it during the winter. The gym is empty and cold, e.g. 60 degrees F. You keep maticulous records on winds, torque, rubber size, max height, duration, etc. so you can do a no-touch flight at the compeition, i.e. one in which the plane will climb just short of the max ceiling height without ever hitting.
You go to the competition. You launch the plane with a rubber width, torque and winds that should take you just below the ceiling. Instead, the plane rockets to the ceiling and diasaster strikes. The plane crashes into the ceiling a couple of times and you don't get a lucky bouce. Your plane evenetually lands on a light fixture. What happend?
Well the gym is full of students and spectators, and all the lights are on. So the temperature is much higher, e.g. 15 to 20 degrees higher, than when you practiced. The humidity is often different, depending on weather conditions.
All other factors being equal, a Wright Stuff plane can fly as much as 20% longer with a 20 degree increase in the temperature at the flying site. It sounds counter-inutitive because the air is warmer and thinner.
The plane will also climb much more rapidly when the temperature is 20 degrees warmer.
Solution: Your first competition flight is a conservative flight, i.e. you launch your plane with low torque and low winds based on your flight logs. Depending on the max height achieved by your plane during the first lfight, extrapolate to determine the best torque and winds for your second "aggressive" flight that will get your plane close to the ceiling.
Practice flights in the gym where the compeition is held early in the morning on the day of the competition are of little value because the gym has not heated up yet.
I have also heard that high humidity can result in lots of broken motors. This happened at Nationals in D.C. a few years ago. It cost Wright Stuff Monster a medal and he was one of the very best builders and flyers at that competition.
Now as to storing your planes, don't worry about the humidity. If your planes have plastic film wing and stab covering variationa in humidity should not result in warps serious enough to ruin your trim. There may be a small weight gain but not enough to significantly impact your time, and certainly not enough to warrant storing your plane in a Turkey roaster bag and risking damge on removal.
I would be interested in Jeff Anderson's take on how to adjust your motor width, torque and/or winding for different humidity and temperature. When I have asked other experts, they seem unable to give clear guidance on how to effectively deal with this issue. I guess it is a non-issue if you are flying an F1D or Penny Plane airplane in a flying site with a 90 foot ceiling.
You have raised one of the most difficult issues with Wright Stuff. After years of coaching Wright Stuff I eventually realized a major problem but could not get an adequate answer, even from experts with 50 years of indoor rubber powered flying experience.
Here is the problem. You practice for weeks or months in your gym, much of it during the winter. The gym is empty and cold, e.g. 60 degrees F. You keep maticulous records on winds, torque, rubber size, max height, duration, etc. so you can do a no-touch flight at the compeition, i.e. one in which the plane will climb just short of the max ceiling height without ever hitting.
You go to the competition. You launch the plane with a rubber width, torque and winds that should take you just below the ceiling. Instead, the plane rockets to the ceiling and diasaster strikes. The plane crashes into the ceiling a couple of times and you don't get a lucky bouce. Your plane evenetually lands on a light fixture. What happend?
Well the gym is full of students and spectators, and all the lights are on. So the temperature is much higher, e.g. 15 to 20 degrees higher, than when you practiced. The humidity is often different, depending on weather conditions.
All other factors being equal, a Wright Stuff plane can fly as much as 20% longer with a 20 degree increase in the temperature at the flying site. It sounds counter-inutitive because the air is warmer and thinner.
The plane will also climb much more rapidly when the temperature is 20 degrees warmer.
Solution: Your first competition flight is a conservative flight, i.e. you launch your plane with low torque and low winds based on your flight logs. Depending on the max height achieved by your plane during the first lfight, extrapolate to determine the best torque and winds for your second "aggressive" flight that will get your plane close to the ceiling.
Practice flights in the gym where the compeition is held early in the morning on the day of the competition are of little value because the gym has not heated up yet.
I have also heard that high humidity can result in lots of broken motors. This happened at Nationals in D.C. a few years ago. It cost Wright Stuff Monster a medal and he was one of the very best builders and flyers at that competition.
Now as to storing your planes, don't worry about the humidity. If your planes have plastic film wing and stab covering variationa in humidity should not result in warps serious enough to ruin your trim. There may be a small weight gain but not enough to significantly impact your time, and certainly not enough to warrant storing your plane in a Turkey roaster bag and risking damge on removal.
I would be interested in Jeff Anderson's take on how to adjust your motor width, torque and/or winding for different humidity and temperature. When I have asked other experts, they seem unable to give clear guidance on how to effectively deal with this issue. I guess it is a non-issue if you are flying an F1D or Penny Plane airplane in a flying site with a 90 foot ceiling.