Ridge Runt (oz5771)


Ridge Runt (oz5771) by John Lupperger 1995 - plan thumbnail

About this Plan

Ridge Runt. Slope aileron trainer. Wingspan 50in, area 275 sq in, weight 18 to 22 oz.

Quote: "Ridge Runt. A Slope Aileron Trainer that flies as good as it looks.

The Hobby Shack Ridge Runt was designed to be an aileron trainer for the pilot wishing to transition from rudder/elevator floaters. However, the experienced pilot will find it to be agile enough for basic aerobatics, and great fun for sport flying. Due to its simple construction and light weight, the Ridge Runt will fly on any slope in light to moderate winds. Its clean design will also allow it to fly in high wind conditions with the addition of a small amount of ballast.

The Ridge Runt can be flown several different ways: it can be flown from the slope, hand launched, high started, or even with a power pod. When flown from the slope, simply toss the model into the wind and fly back and forth across the face of the hill. Initially all turns should be made away from the hill till you feel comfortable with your model.

Although the Ridge runt was designed primarily for slope soaring, it has successfully been flown from a high start. The tow hook should be placed about 1/2 in ahead of the CG (center of gravity) for initial flights. Control inputs should be kept to a minimum during tow, as the model goes up the line very rapidly. Even though the model is quite small its light weight makes it capable of reasonable thermal flying. One advantage to its small size is that you can work small, fast moving thermals, even dust devils!

The model can be set up with a power pod in either a tractor or pusher configuration. For easy sport flying use a Cox Black Widow: for higher speed, aerobatic flight, use a Cox Tee Dee .049 or .051."

Quote: "So by now we have come to the most important point of every test report: the Flight Properties. The next bit is no undue adulation. The Ridge Runt really flies perfectly and - no matter if you go slope soaring or thermal soaring with the help of a tow line - this plane is easy and precise to control! Normal wide turns can be achieved just by using the ailerons - only when you want to produce real sharp circles is elevator movement needed. With the aid of both control surfaces (ailerons and elevator) the Ridge Runt really shows where it's at - tight turns with the wings in a vertical position scratching just a hand's breadth over the slope's edge, one loop after another or slow rolls (if there is enough speed) are so simple to do that you really will enjoy it! When going slope soaring in strong winds, additional ballast underneath the centre of gravity is recommended - I take between 50g and 100g of lead.

It's not only when soaring at slopes that the Ridge Runt shows its good manners. You will enjoy this model just as much when doing high-starts from a tow line. While on the line the Ridge Runt is very stable without any tendencies to brake out and once off the line it reacts even on light thermal winds so that, with just a little kick you can manage to stay up soaring for hours!

The Ridge Runt has a wide range of speed. Due to its slim shape this model produces only low drag so you can fly it at the speed of an elderly jogger as well as at 50 kilometres per hour and more. Even at stall speed the Ridge Runt is very good-natured. First control surface actions slowly die down and then the model dives downwards in a very stable way without rolling to either one side.

At this point I have to thank my wife the for being so kind as to take the pictures of the Ridge Runt in the air - especially since she really is no fan of R/C models (this is still expressed in a very diplomatic way!). I also have to say thank you to Ditmar Geimer and Andreas Frede for their support during the many test flights with the high start line.

Conclusion. If there existed any kind of formula or equation for calculating the efficiency of a model airplane, taking into account kit price, building effort, looks and flight properties, the Ridge Runt would - despite its small dimensions - be not far away from 100%. This model is a fully fledged soarer and a good choice for intermediate pilots starting to fly models with ailerons as well as a perfect 'second' model for the experienced RC-pilot who needs something to take along during holidays. Anyhow, at a kit price of just £27.50, you can't go wrong with this model and will surely have a lot of fun!"

Note: the supplement instructions file is very good. 6 pages, complete with illustrations. Very thorough on construction details.

Update 07/08/2016: Re-scaled this plan to correct full size at 50in wingspan, thanks to anon.

Update 18/06/2018: Added kit review from Aviation Modeller International, April 1996, thanks to RFJ.

Update 14/12/2018: Added kit review from R/C Model World, May 1996, thanks to RFJ.

Update 19/02/2020: Added kit review from Silent Flight, April/May 1993, thanks to RFJ.

Supplementary file notes

Instructions, thanks to turbojoe who posted the scans up onto RCGroups.
Kit reviews.


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Ridge Runt (oz5771) by John Lupperger 1995 - model pic


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User comments

Hi, Steve. Back in 1991, I built a Ridge Runt from the Global kit. It went together quickly and flew reasonably well, not needing much wind to stay up on the slope. As an aileron trainer it's not a bad airplane, but the flat-bottom airfoil really limits rolling maneuvers and I got bored with it pretty quickly. If I were to build another, I would use the E-374 or similar semi-symmetrical section. Thanks for yet another plan from my past!
Moeregaard - 14/08/2014
A great little sloper. I modified mine with the Selig 3021 aerofoil (thickened 10%), lengthened the nose and sheeted the leading edge. Soars well in 5 to 20 knots and is fully aerobatic.
RalphJ - 21/04/2016
Hai Steve, the original wingspan was 50 inches, not 56. Keep up the good work, outerzone is great!
anon - 07/08/2016
You're right. Thanks. Re-scaling this one now.
SteveWMD - 07/08/2016
Hi Steve, here's a couple of photos [more pics 004, 005] of my new Ridge Runt, 20 odd years after my first one! Ready to fly weight came in at exactly 1lb. Keep up the good work on this magnificent site. Cheers,
MikeJones - 24/04/2017
Hello, I'm sending in some pictures of my modified Ridge Runt. I've started from the Outer Zone plans. I've CNC wire-cut the wings from foam with E374 airfoil at the local Fablab and sheeted them with limewood. Built the fuselage as per plans but put the stab low to avoid the linkage intricacies. It was actually a zero-euros project: all surfaces made from scraps of balsa, cardboard and depron; at the end, I bought only the Oracover film. All the other materials have been scavenged from crashed planes or found somewhere in my workshop. It came a bit on the heavy side, 650g rtf (37 g/dm2), but it slopes briskly and neatly in medium-strong wind; a pleasure to build and to fly. Here's some photos of the building [more pics 006, 007] and of the maiden flight that took place on my favourite Genoa slope [more pics 008, 009]. Thank you for your great work at Outerzone. Ciao from Italy,
RaffaelloB - 04/05/2017
Added new photo of the Ridge Runt, thanks to AndyMac [more pics 010].
Mary - 10/07/2017
Please find attached photo for your excellent web site [model photo]. I built this from the kit about 20 years ago. It still flies well, although I have replaced the tissue wing covering (not recommended) with Solartex.
RussellH - 17/01/2018
Last summer I wrote off my original Ridge Runt on a windy day when it inexplicably decided to emulate a fence post in the hillside. I realised it had become my 'go-to' model for slope soaring with the club so, having dug out the reusable parts, I set about building a replacement. Photo attached [more pics 011].
RussellH - 11/06/2019
I built mine in the summer of 2017. A great looking model and easy to construct.
I also did the lower stab thing, with a linkage out the side of the fuselage.
I have to admit to being a bit rubbish at the flying side of things but I have had it out a few times. Might need to dust it off and get it going again.
Graham Patience - 04/08/2019
Hi there, here is my RidgeRunt built from your plans [012-015]. Great fun so far and was a good building exercise! Keep up the great site!
Stephen Harris - 08/09/2021
Here are some photos of my Coyote = Ridge Runt [pics 016-019]. A great acrobatic soarer.
Murat Kece - 28/07/2022
Murat, the Global Ridge Runt and Slec/Balsa craft /Ripmax Coyote are not the same Aircraft. Different wingspan and taper, different fuselage shape, I own both.
Mike Jones - 10/09/2022
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