Some settings for my F3F Skorpion and how I arrived at them.

 

On the weekend I finally tackled trying to improve the handling of my Skorpion and have had a couple of requests to share my settings and how I arrived at them, so here I go.

Firstly I should clarify that I am by no means an expert and any information I pass on has been gained from others at race meetings and from articles such as Kevin Newton’s brilliant ‘how to set up a racing glider’ article from his website (http://kevin-newton.blogspot.co.uk/2001/01/how-to-set-up-racing-glider.html) and Andy Ellison’s article (On The Edge Special 2010 – Setting Up A Slope Racing Glider) in RCM&E. Another clarification from my point of view is that my plane’s CofG is at 110mm from the leading edge at the root of the wing on my Skorpion F3F and I understand that most people don’t fly quite that far back so any measurements or settings need to have the twitchiness of my CofG kept in mind.

One thing Kevin’s article definitely taught me was that experimentation and tinkering are key. Although I haven’t been disciplined enough to record the results of any Tinkering and would suggest doing so to others as it saves all sorts of hassle.

Right then. On Sunday I decided to correct the handling issues I had been ‘flying around’ on the Skorp. I wasn’t comfortable with how the plane was entering or exiting the turns on simulated F3F runs especially using the reversal turn (my preferred turn style). I felt as though I was constantly correcting the plane and fighting it to stay on the course and I noticed that the nose was slightly high through the turns, along with shifting towards the slope with the application of rolling away ailerons. On the ground I checked the current state of aileron differential and they looked to be moving almost an equal amount up and down. This setting was giving me the poor flights. Using the aileron differential mixer on my transmitter I adjusted the differential to have almost zero downward travelling aileron (I was working on the theory that I will see the change markedly if it is a BIG change!). I had to remind myself before the test flight that I would have much reduced aileron authority, especially when landing and turned the aileron-flap coupling and snap flap off for landing (looking forward to getting a Transmitter that can set a landing phase with those mixes OFF at the flick of the Landing switch). Test flight time and the change was pretty extreme! The plane was now pulling away from the slope when ailerons were applied and the nose was very low in the turn. But it was WAY too much of a change as the plane was now barreling back towards me out of the turns and trying to fly behind me! Although it was only a short flight, it told me that I had changed the plane in the right direction. I had just made the adjustment too large. After remembering to flick the three switches and successfully landing I adjusted the differential slightly back towards the starting point giving approximately 8mm down aileron, 20mm up aileron and 4mm up and down flap. These eyeballed (not measured) settings gave me the results I was after on my next test flight (very much a fluke to get it in 3 flights!!) and suit my CofG and my flying style. My plane now exited the turn along the slope at a trajectory that I didn’t have to fight and it’s line was such that I hardly had to adjust it before entering the next turn.

Next up was Snap-flap (SF). The amount of flap/aileron linked to the movement of the elevator (ele-flap mix on my transmitter). Again I subscribed to the more is more school of thought and for the first test flight I tested the difference between my current settings and none by switching it off during some test runs. I hardly ever pull full elevator and don't feel like the plane is close to flicking so didn’t see the benefit in doing the three loop test. I prefer to test for energy efficiency using the reversal turn as per my racing. After practicing with your own plane and learning what is pinging back out of the turn or not, you will know what is best for your plane and flying style.

The first test flight taught me that the amount of SF I was using at the time was an improvement on not using SF as the plane slowed down less when the elevator was used to complete the reversal turn when SF was used. The plane did not maintain it’s energy as well as I had experienced before, so I knew changes needed to happen.

For the second test flight I reduced the amount of SF by half. This change was wrong. The plane lost more energy in the turn. The third test flight increased the SF from my starting point giving me a maximum of around 6mm SF with the full 5mm up elevator travel.  Again I will reiterate two points. A) I hardly ever pull full elevator and B) my CofG is at 110mm. These eyeballed (not measured) settings gave me a much more energy efficient glider which completed it’s turns giving what seemed like acceleration out of the turn.

With my broken F3B Skorpion, I experimented with having the SF on a curve to deliver the SF biased to the start or end of the stick elevator travel. I found that early SF worked better for me than late although Linear SF works best for me. I think I would like to try late SF again though for using the EM turn style.

It is very possible that I will get to the slopes next time out and the conditions will be different and my settings will be wrong. It is also possible that I will want to fly a different turn style on a different slope and the settings I have will make that style hard work.

The best piece of advice I ever received regarding settings is to ‘just play around with them and learn what works for you’.

I hope this encourages some of you to have a play and learn what works best for you and your planes.