Tuesday, June 6, 2017

Sniffer Electric Free Flight Report

In my hobby interests I try to use “adaptability” to enjoy what I have available to me in the local area. Locally we do not have an abundance of open area to fly free flight model airplanes. In the past I have flown small rubber powered models or gliders that if I lost it would not be too upsetting to me.  Somewhat larger free flight models to me can be more fun to build and challenging to get adjusted properly.

In my Build Report for the BMJR Sniffer I described the Sniffer kit that originally I was going to power with a Cox PeeWee .020 engine but decided to use a brushless electric motor and radio control for control of motor speed and dethermalizing (DT). I had thought it would be easy to connect the servo for rudder control but so far I am having more fun with an airplane that is almost free flight.

When I started flying the plane it flew right under power but changed to left for the glide but not always consistently so.  I added a rudder trim tab and forced the plane to fly to the left under power while maintaining a left glide. My concern was the plane might glide too much left but that does not appear to be a problem. The transition from power to glide is pretty smooth. When making trim adjustments it is so nice to be able to shut the motor down immediately or trip the DT to bring the plane down safely if it looks like a crash is likely.

Where I often fly there are many obstacles and if it looks like the glide will go over a building or tree I use the DT to bring it down before reaching the obstacle. This works pretty well except one time it came down into a chain link fence after the DT, no damage however.  If it is close to calm I will leave the power on until the Sniffer is pretty darn high. Most times it circles in the general area without drifting too much. When calm you can fly it around at reduced power and it will just circle around at like 30 feet high.

From my observation I think the propeller freewheeling in the glide has a rather detrimental effect on the glide, it also appears to cause the glide to be left. I say that as when I removed the propeller and did some test glides from a small hill the plane went straight. Spinning the propeller in the glide turns the motor which has a fair amount of friction. I know for better glide performance in P30 rubber power event people try to reduce that friction with their freewheel mechanisms.  I am going to look for a folding propeller for my motor.

This has been a fun project and gives me ideas for other sport models I could use RC DT on. Maybe a rubber powered model. 

Bill Kuhl

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