The Basics of gliders

I have given lots of thought to the subject but I still can't figure out how the pod and glider separate at apogee and not sooner or later on booster-gliders. I'm sure if I saw one it would all make sense but I do not have access to one at this time.

Also is it possible to scratch build one and still have it glide effectively? If so how?

Boost gliders are usually designed to separate at ejection, which you try to have coincide around apogee. With only limited motor delays available, that is sometimes difficult. Sometimes they do separate before or after apogee.

What usually holds them together is a combination of friction on the attaching parts and the fact that that the glider has a lot more drag than the pod does(until the pod ejects a streamer or chute). The kick of the ejection charge and recovery deployment should be enough to separate the glider from the pod. Sometimes the recovery device/shock cord gets tangled up with the glider and you get what is affectionately called a "Red Baron" as the combination streams in as if it had been shot down.

I keep saying "usually" because there is a great variety of glider designs and separation systems that try to improve the likelihood of a successful flight and some rely on other methods to hold things together and make them come apart.

Lots of good info available about building and flying boost gliders on the NAR website at: https://www.nar.org/contest-flying/competition-guide/duration-events/boostglide-duration/ There a bunch of plans there that you can scratch build.

Good luck,

Don

Thank you, that it super helpful!

One tip I have is if you are going to scratch build boost gliders is to invest in a Razor Plane - it will make shaping the airfoil much, much easier. Shaping balsa with a razor plane one of the roads to inner peace.

Ok thank you I might just have to invest in one.

One thing that holds them together is the way the glider/pod fit together. I design them so that the glider "hangs" from the pod. When vertical and under boost (with drag on the glider), they stay together, but at any off angle, or if the pod slows down, they fall apart. Some pictures of my 13mm boost pod glider "Dinky Bird". Top picture is Estes "Eagle" glider (can't find boost pod).

WOW1 Did that ever get mangled... But I think you can see how they attach.

Oh, and scratch build, and glide effectively? You bet! For your first "home rolled", however, I suggest you try copying an established design. The Flat Cat is an excellent design to start with!

https://www.spacemodeling.org/jimz/mpcr216.htm

George has an interesting page on the subject at https://georgesrockets.com/GRC/Glider/GliderHooks.htm

Stine's Handbook of Model Rocketry also has some basic design guidelines for the flatcat glider.

Hand-tossed (and catapult-launched) gliders form an excellent conversion source for rocket gliders. Here is an great web site about making your own, with three tiny gliders that will fly on a 13mm boost pod. I've built/flown the Dog Chew.

https://chuckglider.blogspot.com/2010_07_01_archive.html