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Author Topic: glider sizes ?  (Read 234 times)
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enyaws
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« on: October 15, 2020, 11:01:43 PM »

I'm a bit confused on OUTDOOR glider sizes in reading AMA rules.  I see there are 3 separate forums here at hip Pocket.   Catapult, Hand Launch, and tip launch.  It appears that catapult is limited to 1.5 oz.  Tip launch is limited to 1 meter.  I don't see a size limit on hand launch but am aware of some of the larger he man events.  Is there a size limit on hand launch and if not what is considered average?
If a design or plan shows a hook or notch for the rubber indicating it is for catapult, is it safe to assume it will build easily at or below 1.5oz?   A couple of years back I thought i heard about a new provisional event for 30" bungee launch.  Has that event gained any traction or is interest poor. Perhaps these questions should have been spread across the 3 forums.  TIA for any replies that aim to un-confuse me.  I have found the AMA Glider site by the Krempetz clan. Much appreciated info. Wayne
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lincoln
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« Reply #1 on: October 16, 2020, 05:22:24 AM »

Since CLG limits the size of the catapult rubber, the 1.5 ounce rule is pointless in practice. It just won't launch very high. I suspect that 0.5 ounces is much closer to optimal. The Straight Up is popular for CLG. You'd have to use oak, or maybe old Guillows wood, to get it up to 1.5 ounces. OTOH, I suspect with care and careful selection of balsa, half an ounce is possible. I seem to recall having 12 inch CLG's that weighed more like a quarter of an ounce.

 You may run across a few catapult launch gliders designs which aren't intended for the current rules. Using more rubber on a pole can be very exciting and somewhat dangerous for bystanders. A robust model would be required, but it may also be larger.

Unless I'm mistaken, tip launch falls within the hand launch rules and is not a separate event. The one meter limit is in the AMA rules for hand launch.

The Flying Aces Club has an "unofficial" event for scale bungee launch  gliders. You can find out more on their web site. I seem to recall that people have been doing 36 inch bungee launch gliders over in the UK. The National Free Flight Society had a 30 inch hi start launch provisional event, but I don't know if it's still flown.
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enyaws
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« Reply #2 on: October 16, 2020, 09:44:11 AM »

Many thanks for the reply Lincoln! I did not have a grasp of how large a 1.5 oz. glider could be. It is now clear that the rubber limit is actually what keeps them withing reason.  I've built a fair number of gliders all unsuccessful at trimming and transition.  Having a couple of grandsons who are showing interest in free flight, I'm wanting to try CLG again as a reasonably quick build that will get them on the building board and in the air. My last build was the Q.CAT 18-2.  I was impressed with the Ralph Ray Tumbling Pigeon D.T. and carbon tube fuselage.  I fear these are too complex for kids starting out. I have some ideas for sanding jigs that will aid in airfoil forming.  I'm thinking that a larger glider might not be too fast a launch.  Perhaps backing off on the launch rubber would slow things down a bit.  Thinking about it, I did not learn to drive with a brick placed on the accelerator pedal Roll Eyes
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Jasco
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« Reply #3 on: October 16, 2020, 12:26:08 PM »

I'm not a paid spokesman, but if you head over to https://jhaerospace.com/ he has more CLG kits than you can shake a stick at. I recommend the "1-sheet glider" for kids of all ages.  I had a blast with mine and the kit is complete with rubber and a dowel for the catapult. Easily flew 1 minute in light summer air.
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enyaws
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« Reply #4 on: October 16, 2020, 12:40:36 PM »

I'm quite familiar with Johsh's site and getting real serious about clicking the buy button.  At my age, I'm still adjusting to what this stuff costs today. Also it frustrates me to allow the kids to believe they have actually built something that came all nicely laser cut.  That said I'm still wasting my time unfolding maps rather than using GPS.  Thanks for the reminder.  We are actually quite lucky to have so many supplies available online.  Rough on a brick and mortar stores, but good for the hobby.  I guess removing builder of the model rule was a good move in some ways.
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Tmat
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« Reply #5 on: October 16, 2020, 02:23:33 PM »

There are no size limits on catapult gliders other than the 1.5 oz maximum weight (42.5 grams). Because the launch rubber is limited, most gliders are under 30 grams. I've never heard of a AMA catapult glider at 1.5 ounces. It just wouldn't launch very high. Typically, for contest gliders, wing spans vary from 12" to 20" with 16" to 18" being typical and weights of 20 to 25 grams.
I've flown catapults as small as 6" span and as large as 24" span. 6" is for fun.

1 meter span is the max for Tip launch but this applies to hand launch as well (Tip launch is considered hand launch). From AMA rules:

An Outdoor Hand Launched Glider is a non-powered model aircraft designed to
fly outdoors with a projected wingspan less than or equal to one (1) meter (39.37
inches).

Any old hand launch glider design can be easily converted to catapult glider with the addition of a hook and grip. Tip launch requires a different tail surface arrangement to handle the big yaw at the launch.

Tmat
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Jasco
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« Reply #6 on: October 16, 2020, 02:58:14 PM »

I do my share of scratch-building, and obtain masochistic enjoyment from cutting out wing ribs, but I think laser die-cutting is the best.  I just wish I had my own!
I watched a video of Josh building a Wakefield using laser cut cross pieces and uprights. I just about lost my mind.

Anyway, the kits are a nice way of giving the kids a little assembly experience and get them in the air without the drama of their first bloody encounter with an exacto knife.

I've tried launching a couple of my larger gliders from the tip. They roll upside down and don't recover.
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enyaws
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« Reply #7 on: October 16, 2020, 10:16:03 PM »

Thanks all for the replies. Tmat's comments were especially helpful.
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lincoln
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« Reply #8 on: October 17, 2020, 07:00:50 PM »

For kids, or if your time is limited, you can actually get some air time and fly on smaller fields with very simple gliders with flat plate airfoils. I've had good luck with a 10 inch version of John O'Sullivan's Sparrow with a hook added. It's probably a good idea to extend the fuselage past the tail a little so you have something to grab. When holding it further forward, the tail kept hitting my fingers. Maybe a t-tail next time. I found a Budd Kicker helpful. My best time was a couple of minutes, which is plenty long when there's a breeze. The Sparrow is on Outerzone, but I'm sure some of the gliders on Hip Pocket could be just as good. Maybe the FAC Tick, meant for the FAC's tiny glider event.
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Tmat
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« Reply #9 on: October 17, 2020, 07:43:53 PM »

I fly a tiny 8" glider in the parking lot across the road from my house if the evening is calm. With a flat 1/16" "airfoil" (just rounded leading edge) the little glider does between 30-40 seconds with a 1/8" loop of rubber. The height gained is quite good, but the sink rate is high without an airfoil, thus ideal for a small field.
It's Hummingbird Model products "Hummer Bee" clg.

Tmat

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