Why You Should Glide Test

The glide test is a helpful method used to determine whether your plane will fly - and you should definitely be using it!

If you've listened to one of our recent Flite Test Podcast episodes, you may have heard Josh Bixler talking about "hacking up foam and seeing if it flies". In essence, this is how almost every FT kit has been formed! What Josh is talking about is doing the absolute minimum to get a plane in the air before going all-out and completing it. Glide testing is an integral part of this, so here's how you should go about launching your creations into the great blue yonder for the first time.   

It took me a while to get over the idea that 'it's better to just power up your shiny new airplane and go for it' in favor of a more measured approach with the glide test. Especially when talking about the types of DIY airplanes that we love here in the Flite Test community (with light wing loadings and rarely a wingspan over 50"), most of the time, there's little excuse not to. 

The glide test has helped me catch some problems early on when working on past projects. An example of this would be when I was working on a Blunt Nose Versa wing when they had just come out back in around 2014. A quick hand-launch into a grassy field one afternoon taught me that the crucial CG of the flying wing was too far aft; after the launch, the plane tried to flip back on itself. After a few alterations, I could fix this and have success with the maiden flight - I doubt it would have been successful if I hadn't first found the problem. 

Doing a glide test is also a great way to settle those nerves that come with the inevitable first flight of a new airplane. Heeding the words of Josh, the first prototype of a de Havilland Vampire design I was working on was quickly assembled and taken out to a field with long grass for a quick chuck. 

It clearly demonstrated that it wanted to fly, so, without much hesitation, I slapped on a propeller and took the plane for a quick test flight. It was perfect. 

Of course, it might not always be possible to carry out a glide test. For one thing, the plane may be too large have a high wing loading that requires the speeds involved in a glide test to go significantly up. Effectively, with some models, might not have the means to run along and chuck the model forwards. Some models that might fall into this category are the bigger warbird and jet models produced by E-Flite, Durafly and Dynam. 

Secondly, you might not have the right location to glide test your model. The perfect location would probably be some sort of open field with long grass or other soft vegetation to cushion the landing (or crash!). If this is not available to you in your climate, you can still get away with using your normal flying field or lawn.

The Blunt Nose Versa wing after the center of gravity issue had been identified and fixed through the process of a glide test. 

The de Havilland Vampire I proved with a glide test. You can read all about this design here. 

A Durafly P-40. This plane wouldn't be the ideal candidate for a glide test as it has a relatively high wing loading for a model of this size.

How To Do a Glide Test

A glide test can, for all intents and purposes, feel a little odd. It doesn't seem natural to toss your precious airframe to the ground. However, you have to have some faith in your airplane that it will glide. If you've built it right and it is the right size and type to be glide tested (as mentioned above), a good plane will fly without power.

Location:

As mentioned above, choose somewhere with long grass if possible. If you live in a climate without long grass, you can still do a glide test, it may just be a little less forgiving. Also, it's worth mentioning that you should wait for a calm, predictable day. You don't want a sudden crosswind to catch a wing and roll your airplane into the ground. 

Aircraft setup:

Set the plane up as you would if you were taking it out for a maiden. Install the battery in the right CG position, turn on your radio and power up. Set your rates to high. If you have a propeller on the nose of your plane, you may want to remove it. This will avoid it getting damaged on landing. It will also remove the temptation to power off and fly away! 

Process:

1. Pick up the model and face it into the wind whilst holding the fuselage.

2. Walk or run forward into the wind but retain a grip on the model. Feel how the air works around it and wants to lift it out of your hands. 

3. Repeat the process and firmly launch it forwards almost parallel with the ground. Aim for a point in the distance. You don't want to throw it too high and stall, but equally, you don't want to lob it into the ground! 

4. Control the airplane unpowered to the ground with your radio. 

5. Repeat with alterations to the CG and controls if necessary. 

In some ways, the glide test is the perfect incentive to spend less time building and more time flying before becoming invested in your creation. If it simply doesn't fly - you can fix it! The next step is paint, decoration - and of course powered flight.  

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Article by James Whomsley

Editor of FliteTest.com

Contact: james@flitetest.com

YouTube Channel: www.youtube.com/projectairaviation