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Archive for November, 2017
Posted by VicT | Nov 30, 2017 @ 05:44 PM | 3,665 Views
Full size aircraft manufactures use throttle detents for a number of reasons. Many have a gate that seperate flight idle power from reverse thrust reversers or reversible pitch operation. There is no switch to move just move the throttle below the detent/ gate and you are producing reverse thrust. In model flying we use flaps, slats, or prop wind milling drag to slow down. I have a reversible ESC that uses a spare channel for reverse thrust but I want to use windmilling drag instead. So how does this work?

If your ESC does not have the brake activated/enabled just bring the throttle stick all the way down to the stop and the propeller will turn as fast as your airspeed will allow. Even when you slow down to zero airspeed the prop will turn until centrifigual forces stop and then the prop will stop until airspeed increases and then the prop will start windmilling again. The windmilling drag may cause turbulence over the elevator and/or rudder that can reduce pitch and yaw control. I have had some models that have temporarily been out of control until the turbulence diminishes. This can be very alarming so I have used folding props to reduce drag and flaps to increase drag.. recently I have been trimming out a friends 43 Rick Stick. It can be fast but not slow down. It was not designed with flaps and although I could install flaps I want to know if wind milling prop drag is sufficient to slow the model down for landing. Another friend takes off with high...Continue Reading
Posted by VicT | Nov 22, 2017 @ 08:26 PM | 3,648 Views
The stock wing bolts are too short to hold the wing panels to the front or rear brass threaded inserts. I originally made wing hold down bolts from 3mm Allen head bolts screwed into a dowel. A washer was made from a credit card type plastic with a music wire pin to hold it in place. A nice custom bolt but went to Ace Hardware and bought the 50 mm long 3 mm bolts with a metal washer for my buddies to use. I can use my fingers to hand tighten or a Phillips head driver. See sketch below. See post 619 for picture info.
Posted by VicT | Nov 15, 2017 @ 11:55 PM | 3,105 Views
The purpose of adding a second elevator servo is for safety purposes. If one servo fails and that elevator fails to move then the other elevator servo and elevator will provide pitch control. Half of the normal elevator surface area will be used so reduced pitching power will be available. If Self Level is on it is assumed that the gyro will command more movement of the elevator half to regain a level pitch attitude. In case of one elevator servo failure the remaining servo and elevator will allow some pitch control for a descent and landing. Both servos are connected to a Y cable and use the same signal. The elevator horn and servo arm holes are equal so the elevators have equal throw and endpoints.
Posted by VicT | Nov 13, 2017 @ 01:27 AM | 3,191 Views
The Valiant 1.3 speed control (ESC) comes with the propellor brake off which causes the prop to spin (windmill) when the throttle is at idle/off. The windmilling prop spins faster at faster airspeeds and slower at slower air speeds . The drag of the windmilling prop can be beneficial if you want to decelerate such as on vertical downlines or for rapid descents. So why reduce drag more by "feathering or stopping" the prop from spinning or windmilling?
The spinning prop causes turbulent air over the elevator and rudder and their effectiveness becomes diminished. Stopping the prop by activating the hard brake causes the slipstream over the rudder and elevator to be smooth or "laminar". This increases control effectiveness and authority. In addition to smother control there is less frontal drag so you can glide for longer distances. This helps make it back to the runway in case your ESC stops power to your motor. This can happen when you fly too long or your ESC/ BEC fails and your Scorpion or 430 backup 2S pack (if installed) takes over for receiver power. A feathered prop helps reduce drag when you enter a thermal and/or you practice a climb and glide fun fly task.

Excerpts from the ESC manual (E-flite 30-Amp Pro Switch instructions) are here with my comments.

Remove the prop to prevent injury. Enter the Programming Mode 1. With the battery disconnected from the controller, and the transmitter turned on, first move the throttle...Continue Reading
Posted by VicT | Nov 05, 2017 @ 11:27 PM | 3,037 Views
My fellow clubmember Jack W took my suggestion and purchased a Valiant 1.3 M. He had been flying his Apprentice and Timber and enjoyed both but damaged his Timber severely. I told him that the Valiant Flys faster, longer, and almost as slow as the Timber and already comes with the Valiant landing gear that we have been putting on our Timber models. By moving the Valiant gear full forward in the belly battery compartment of the Apprentice and Timber the pitch over forces are minimized. The Valiant gear can be moved forward in the Valiant battery compartment for the same advantages and it is much easier and quicker to do.

Jack had programmed his Valiant with SAFE Select on the B switch and after verifying controls to have proper throw I proceeded to maiden his new Valiant. I put the Valiant on the short grass and slowly increased throttle for break away thrust. The grass was only about 1 high but created just enough drag to cause a pitch over. I could bend down and give her a push with full up elevator to get her moving but knew a forward gear would solve the problem. I had modified another clubmembers Valiant (Bob W.) and after 18 hrs of dual time the gear had held up even with my severe doughnut stress test.
I had used ply and hardwood to screw the gear in and it took about 3 hrs. I wanted to do it quicker and at the field. Heres how I did it.

I removed the 4 bolts and the Valiant gear. I then lightly sanded the aluminum legs that form the U shape....Continue Reading