Blog home  >  RC thermal and slope gliding 101
PermalinkSubmitted: 1:07 am on May-14-2015By: fatedev.com
With more people buying ready to fly (RTF) models these days the appreciation for how a model works and why is going more and more lost. One of the key areas of knowledge I see getting less and less each generation is gliding and the basic knowledge that can make the difference between a 10 minute or hour long flight times.

Slope soaring

The art of using the wind being blown up a steep embankment (a hill, mountain and even man made structures).

First of all it does not matter if you do not have mountains or such at your location, if you have wind and a place where wind is angled upwards then there is a good chance you could slope soar.

The basic effect is simple enough where wind travels along the ground surface (somewhat) undisturbed for a clear way until it is forced to change direction upwards over a peak. This creates an uplift and many other complicated effects but in short provides the lift you need to stay in the air.

As long as you have a good amount of wind then you can fly anything from Discus launch type models all the way up to full scale gliders. Finding a good spot is the hardest part and requires lots of testing, all too often I\'ve seen people give up after a few attempts when the best lift spot was not so far away as it turned out later.

Just by looking you can most likely find the best spot. For instance if there is grass on the ground then the direction it\'s being blown about can indicate where the most air is being directed, other indicators such as holding out a scarf or such will show how gusty or stable the wind is. The closer towards the peak of the embankment you go - the stronger the wind will be and it is here that it is best to launch your model with a strong forward and level throw.

Thermal gliding

Gliding on thermals is one of the most relaxing types of flying in my opinion, on the right day you can stay up until your bored and fly on one battery pack all day. So how do you find the best spot?

Thermals are all about one thing - heat. Many people often make the mistake of trying to go gliding too soon in the day even when it seems hot, this is because people confuse heat from the sun coming down with heat released from below.

Thermals are rising pockets of hot air which can provide massive amounts of lift in a very short space of time. So the best time to find thermals is actually mid-afternoon after the ground and objects have had time to really heat up and are giving off lots of heat.

The ground / earth is your biggest friend and being on the right type of spot can make all the difference. The general rule of thumb is the darker the colour the better the gliding, as dark colours absorb more heat than lighter colours that reflect heat.

So bare earth, farmer fields are golden, additionally plant life such as farmers crops, trees and such are also great retainers of heat and will provider thermals later in the day.

Remember to take the wind into account, for example if the day has a slight breeze but is hot and your flying over farmer fields then the thermals will also be blown downwind. Seems obvious right?  well apparently not as we often see people losing height directly over fields when the thermal lift they wanted was just in reach.

Finding multiple thermal spots can be critical on days where you seem to get less lift. Only by revising the same spots over and over can you learn which areas give the best lift so when you cannot seem to find a spot you know another place to quickly go to. By learning these things you can prolong your flight times massively and stay up for a long time even on days where most people seem to be going home early.

I prefer electric gliders as in areas like this the days of strong thermals are few and far between. However the lift is still there if your willing to go high enough for it.

Days to skip trying for example are when previous day was raining and the following day was not so exceptionally hot, then the ground is at best still drying out and certainly not giving thermals. When the day is hot when your out of the wind but in wind seems colder (basically a sunny but not warm day) then again the wind will be sapping out all of that precious heat.

So what to do if your not getting good weather?  Use an electric glider and fly down wind from a residential or industry area (away from population obviously), if you go high enough then these types of places are ALWAYS giving off heat just the thermals will be blown around like crazy so its not easy but it IS possible!