Straight Up (oz15549)

 

Straight Up  (oz15549) by Joe Mekina 1995 - plan thumbnail

About this Plan

Straight Up. Catapult glider model.

Quote: "Record-setting model shows the way to go in new Catapult Glider event. Straight Up, by Joe Mekina.

Catapult gliders have been around for a while in various forms, including the pole-mounted catapult variety that became popular among several free flight clubs in the late 1970s.

In the mid-1980s the Central Indiana Aeromodelers began promoting a simple set of miles with hand-held catapults. It wasn't long before the event gained popularity in local and regional meets and became a provisional AMA event in 1993.

In 1994 Catapult Glider became an official AMA event and gained further in popularity, especially in the Midwest. The event has brought many old hand-launch glider (HLG) fliers out of retirement who can now fly again, and it allows the Juniors to 'throw' nearly as hard as the adults.

The rules are simple: The contestant must launch the model with a hand-held catapult, consisting of a single loop of IA rubber with a maximum length of nine inches, mounted on a dowel with a maximum length of six inches. To keep the event simple, no limitations are put on the glider. except for a rigid-wing requirement, prohibition of auto (variable-geometry) surfaces and weight of no more than 1.5 ounces.

Six flights are scored, with a maximum flight time of two minutes per flight. All flights are scored, regardless of duration. If the contestant scores three maxes in his his series of six flights, he proceeds to the flyoff flights. The flyoff flights proceed with the same two-minute max until a max is missed. Again, all flights are scored, so consistency becomes even more important.

One way for a catapult glider to achieve its highest potential is to trim it for a nearly straight-up climb - hence this model's name. HLG fliers have long known of this technique, but since its nearly impossible to throw a HLG straight up, enough incidence was ually added to permit a somewhat more shallow launch. This increased incidence also added to consistency and helped make the launch less critical.

Because a hand-held catapult glider can be launched at any angle with consistency, this model takes full advantage of a trim technique that is nearly straight-up. Combined with its simple construction, light weight and spin-tab dethermalizer, Straight-Up makes a very competitive model. Try one or two - they are fun!

Construction: Attention to detail is the difference between an average glider and a great one!

Adhesive: Thick cyanoacrylate (CyA) glue works well, though other types of glue may be substituted if desired.

Wing: Choose a medium-weight (7-lb stock) piece of 1/8 balsa, preferably C-grain. Cut to the planform shown, then carve and sand the airfoil, being careful to maintain the high point as indicated on the plan..."

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Supplementary file notes

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Straight Up  (oz15549) by Joe Mekina 1995 - model pic

Datafile:
  • (oz15549)
    Straight Up
    by Joe Mekina
    from Model Aviation
    August 1995 
    15in span
    Glider F/F
    clean :)
    all formers complete :)
    got article :)
  • Submitted: 13/09/2024
    Filesize: 112KB
    Format: • PDFbitmap
    Credit*: theshadow
    Downloads: 420

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User comments

The Aerocraft Apache is already listed as oz13451, although this plan contains the note "updated 01/06".
Duane - 21/09/2024
Doh. Ah ok right, runs out this is (was) a duplicate entry, see Apache (oz13451) for the earlier post. Hmmm ok, bear with me, will move things around, put a new plan here in this slot.
SteveWMD - 21/09/2024
Apologies for the confusion. Starting again. Ok, have replaced that duplicate file (the Apache) with a new plan here in this slot. Those of you looking for the RC Apache, see previous posting at Apache (oz13451) for that plan. Here in this slot now we have the FF catapult glider 'Straight Up'.
SteveWMD - 21/09/2024
The plans were drawn Incorrect. I made an honest mistake and never caught it until they started showing up at meets when I noticed the tip dihedral looked excessive. I was surprised at how well the model still flew with the excessive tip dihedral. Lee Campbell kitted this model for years, he told me a few years ago he had sold over 10,000 of them, one of his best selling kits. It is sill available as a kit from Retro RC see http://retrorc.us.com/catap... The tip dihedral shown on the plans is 1-3/4 in, it should be 1-5/8 in. Build one and have fun! Joe Mekina
Joe Mekina - 21/09/2024
Hi Joe - it's always a pleasure to hear from actual designers, here. Do you have a drawing to hand that shows the correct dihedral angles? We'd be happy to post that up here, if you have one available.
SteveWMD - 21/09/2024
I built one of these years ago. A bit overweight, but it still flew well. It's been a while, but I remember seeing it roll out from inverted at the top of a launch, with very little loss of altitude.
I modified it with a slightly bent up trailing edge on the stab, thinned out, so it bent down at launch airspeed, but was very stable, with a c.g. forward of the usual spot. Kind of finicky to get right, but then it would launch consistently, almost straight up, with no tendency to loop. It wouldn't dive out if upset by a gust.
LR - 21/09/2024
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* Credit field

The Credit field in the Outerzone database is designed to recognise and credit the hard work done in scanning and digitally cleaning these vintage and old timer model aircraft plans to get them into a usable format. Currently, it is also used to credit people simply for uploading the plan to a forum on the internet. Which is not quite the same thing. This will change soon. Probably.

Scaling

This model plan (like all plans on Outerzone) is supposedly scaled correctly and supposedly will print out nicely at the right size. But that doesn't always happen. If you are about to start building a model plane using this free plan, you are strongly advised to check the scaling very, very carefully before cutting any balsa wood.

 

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