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RC Weekend Summary

Posted by on March 25, 2008

Last Friday, after running at Rancho San Antonio, I flew a ParkZone Cessna 210 Minium at the RSA flying area. Initially, it was a little windy, and the Cessna was being taken away by the wind, but I eventually got the feel for hovering and penetrating against the wind with the use of the throttle and elevator controls.

On Sunday morning, I finally got the Pico Stick up into the air with a ROG takeoff. It looked so majestic with its slow silhouette against the morning sun. Unfortunately, I didn’t get to fly it too long because the battery on the DX6 transmitter gave out. Because of the short run time of the stock Nicad battery, I purchased a NIMH replacement from cheapbatterypacks.com. The servos were a little too far forward, pulling the elevator down and the rudder too far to the right, so I just slid the whole assembly holding the servos forward and secured it with a twist tie. The included motor from MAE is very pleasantly quiet.

I put a HobbyZone SuperCub tail wheel (only $2.99!) on the tail of the FIK 100, and it’s doing a much better job of supporting the tail for ROG. I still have to get a successful flight with that plane!

It’s interesting how much I care about the wind now that I’ve started flying RC airplanes. The early morning and evenings are calm, but the winds are high in the mid-afternoon. I’ll have to look into why this daily cycle occurs.

Ah, here’s the answer from USA Today:

Q: What causes wind and why do we feel it least during early morning and at night?

A: Wind is the result of forces in the atmosphere acting to move air around. One of the most dominant is the pressure gradient force, which shoves air around to try to balance differences in atmospheric pressure. The stronger the gradient, or change in pressure over any given distance, the stronger the force and faster the wind blows.

As air moves over rough ground, a frictional force of the air interacting with the terrain tends to slow it down. You can think of wind as a vast river of air thousands of feet thick that moves steadily over and around everything on the ground. It does this regardless of the time of day; it is more dependent on the location and strength of pressure systems. Winds most often are stronger away from the ground where the frictional force doesn’t apply.

But, as the sun comes up and heats the ground, rising warmth mixes the slower air near the ground with air moving faster that’s above. While slower-moving air is being drawn upward in the mix, faster-moving air is pushed downward, creating breezier conditions by day. After the sun goes down, as well as before it gets strong enough to warm the ground in the morning, this mixing process isn’t happening. So winds at night and in the morning usually are weakest. Of course, storms and fronts can mix the air anytime, night or day.

Learn lots more about wind by visiting USATODAY.com’s What and why of wind index.

(Answered by Chris Cappella, USATODAY.com weather team, Feb. 19, 2002)