Pacer oz7186

 

Pacer - plan thumbnail image

Pacer - completed model photo

This plan was found online 14/05/2016 at: http://www.rcgroups.com/forums/showpost.php?p=32952465&postcount=101
Outerzone planID: oz7186 | Filesize: 397KB | Format: • PDFbitmap | Credit*: Circlip, RFJ, rchopper56

   

About this Plan

Pacer. Radio control sport/pattern plane. For Cox TD .049 power and 2 channel radio. Uses the Ace foam wing, so no wing ribs or wing layout details are shown on the plan.

Quote: "Everyone knows about little 049-powered RC models. They are twitchy, fragile, buzzy things that dart around in a state of semi-controlled agitation while cluttering up the sky. They get in the way of the serious fliers with their serious planes. They are OK for the kids, but a grown man who wants to experience what RC is really all about with a really groovy responsive ship has to have a six-foot, six-pound, 60-powered job, complete with at least six channels. Right? Wrong!

Today's state of the art has changed all this, and a new breed of clean responsive craft is on the way. They not only look like, but fly like, their big competitive brothers; and at the same time offer some very considerable bonuses. In an age of growing shortages of energy, you can now have five and ten minute flights on one or two ounces of fuel. Long weekend trips to the field can be supplemented by a walk to a nearby playground, as all you need for an hour's session can easily be carried in two hands.

A few 60 pilots have been impressed enough to state their belief that this could be a great way to sharpen their competitive skills, and cut down on those 30 gallon summers. A study of the plans will indicate ease of assembly, with a minimum investment of time and money.

The Pacer may well turn out to be the father of this whole new family of RC craft. The concept is an audacious one, made possible by a combination of three essential elements: the availability of high-quality miniaturized RC gear, an engine capable of delivering an immense amount of power per ounce, and imagination. The three ingredients are not new; this particular combination is.

DESIGN PHILOSOPHY: It is not generally understood that an airplane, large or small, is first of all an idea. Sometimes vague in the beginning, the idea is filtered through past experience, practical considerations of available materials and methods, a clari-fication of goals, and a measure of intuition. When successful, the result is a collection of parts moving together as one to form a new entity - which sometimes, though rarely, equals or exceeds the hopes of its creator.

In terms of experience, the last dozen years have witnessed the birth of over sixty original RC designs by the author. There have been successes and failures, and the latter have been the teachers. Risk is always the constant companion and, from this, we learn to enjoy the trip - regardless of the outcome. Nothing is ever wasted, for the failures are seen as a necessary part of learning to bracket the errors.

Always there are the decisions, and each usually represents a trade off - but not always. A designer often feels he must choose between aesthetics and per-formance which, in turn, results in either an easy-to-build 'Ugly Box' or a highly complex 'Slick Brick.' This assumption that it has gotta be this or that is false, for the underlying premise of all good design is simply that form must follow function. Neither ugliness nor complexity ever made a model fly better. If either type worked well, it was not because of, but in spite of, these limitations. The current practice in model aircraft design is often so simple that anyone can become an expert overnight by following one basic rule: If it don't fly too good, stick on a bigger engine.

It is almost incredible how successful this method is, and surely helps explain the popularity of using larger and larger engines on increasingly smaller air-planes. Effective as the method might be, it does not really present much of a design challenge. The Pacer is the result of a challenge, a desire to see how much performance could be coaxed forth, while working within the confines of an RC payload, on one hand, and the available power of the Cox Tee Dee 049-051 on the other.

The goal was not to achieve a VTO trip to Mars, but rather to find a harmonious relationship of parts which would result in the superior flight char-acteristics usually associated with larger, high-powered pattern planes.

HISTORY: While not a committee, several modelers were involved in the development of the concept.

The plane that triggered the action was a P-51 Ace Warbird (oz7023) fitted with rudder, elevator, strip ailerons and a hot Cox 051. Tom Runge had brought it to Madison on a visit in the Summer of '73. His flight demonstrations included low inverted passes, and most everything else in the book. None of us had ever seen a 1/2A ship perform so outstandingly, which was a credit to both pilot and plane. Riding home from the field, a discussion among Tom, Frank Baker and myself explored the idea of taking another look at small, high-performance models, which would begin where the Whizard (oz5253) and Warbird left off. We agreed that it was well within the realm of the possible and, if successful, might be just the thing to make the small RC plane respectable. Work started the following day.

While Frank proceeded with a highly modified Whizard - a cabinless mid-wing - I was approaching the problem from another angle. Under Tom's watchful eye, a new design began to take shape. All of the inherent stability of the Whizard was designed out, to achieve the desired neutral stability of a pattern ship. Moments were lengthened, to smooth out elevator response, and every part made as clean as possible. Following Romey Bukolt's Warbird lead, the retractable landing gear problem was solved in the simplest possible manner - elimination. (An old artists' adage advises: when in doubt - leave it out!) In a spirit of fun, it was called the Mach None (oz2285). Two prototypes were cut before Tom left for the NATS and home.

First flights of all three planes took place about the same time, with Frank and I in Madison and Tom in Omaha. All tests exceeded anything we could have hoped for, with absolutely no resemblance to any previous experience with planes of this size and power. Elimination of the leading gear reduced weight and drag to a point where performance took a giant step: Large, open looping maneuvers were possible. Aileron response was crisp and precise, granting true axial control - but not at first. With airspeeds in the 60-70 mph range, response was so quick that the first flights were all over the sky, and two rolls resulted when one was intended. Some of the squarest loops yet seen at our field were caused by the mere twitch of a thumb. This problem was solved by simply reducing control surface throws.

When the engine quit, the clean machines kept right on going, and none of us could hit the field with our first five landings. It was rather incredible to come across the fence at less than ten feet of altitude, and watch the damn things sail clear across the field into the brush. In time, we learned to kill off speed with a combination of dead stick loops, rolls and a nose high attitude. Here, the low speed stall characteristics of the Ace foam wing, in combination with light wing loadings, allowed 'wheels up' touchdowns at ridiculously low speeds.

Several of the more experienced pattern fliers couldn't believe their eyes, and were soon standing in line to try their hands. They quickly discovered that the major difference in technique was dictated by the visual limitations of a small high-speed model. The solution was to fly close in and lower than usual to maintain visual orientation. Strong simple color contrasts played an equally vital role in this matter.

Mention should be made that only two servos were used, for while the Whizard had been previously tested on four channels, motor control was not really necessary and the rudder was rarely used. So, a decision was made to go with two. The Mach None suffered a loss of spins and snap maneuvers on its two controls, but the increased perform-ance of the lighter wing loading made it a desirable trade. On the other hand, Frank went to a coupled aileron-rudder arrangement, which gave him the whole stunt menu with almost no weight penalty. Dealer's choice. Seeking even more, his next move was to build an 049-size version of the Warlord (oz9012). Sleek and fast, the only problem was a flutter of the flying stab, which was resolved by going to a Nyrod linkage.

Meanwhile, back at the drawing board, my new one was coming into focus as a direct result of Tom's urging. Goal: a simpler, stronger construction involving less building time; elimination of rubber band wing hold-downs, and an even cleaner collection of parts designed to stretch performance closer to the ultimate. As some of you alert ones may have guessed, it was called the Pacer. It was built in one week and displayed at Toledo, along with Tom's new Mach None. The reviews were raves, although a few die-hards doubted the performance claims..."

Update 16/01/2017: Added article, thanks to RFJ.

Update 18/01/2019: Added alternate plan, thanks to rchopper56. The original Pacer design used the Ace foam wing. This here is a modern redrawn plan that shows details for a built-up wing construction.

Quote: "Hi Mary and Steve, The attached file of Owen's 1/2A Pacer is the same drawing that was and still is at Dave Fritzke's site but rearranged and is now just one sheet. The drawing dates back to 2004 and at that time, tiling seemed to be the way to present a drawing. The drawing shows a balsa wing for those who cannot find the foam wing the original called out. Gene."

Supplementary files

Article.
Alternate plan (shows built-up wing).

Corrections?

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oz7186 datafile

Pacer  
by Owen Kampen
from American Aircraft Modeler
August 1974 
44in span
Tags: IC R/C LowWing
all formers complete :)
got article :)

 

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User comments

I built this model around the time it was first published and it was superb. With a TD 049 it was so smooth, a bit better a plane than its pilot. Sadly pulling up elevator whilst inverted at twenty feet saw its demise but it was without doubt the most precise model I flew.
AndrewHare - 13/11/2015
Hi, Steve. I built a Pacer from plans, back in 1978, and my experience was very similar to Andrew's. At 22 oz. and with a good Cox TD .051 up front, it was smooth and fast, and would do anything that didn't require rudder. In fact, it flew so well that I eventually flew it right into the ground. Current modelers who were not around when the Pacer launched the "1/2-A Revolution" in the early 1970s would have been amazed at the sudden popularity of Ace's Pacer and Mach None, along with the multitude of designs from other designers and manufacturers. All of this came at a time when the first lightweight R/C gear was coming onto the market. Sadly, the moulded foam wings made my Ace are no longer available, but any capable scratch builder should have no problem coming up with an alternative. As with any model, excessive weight is the enemy of performance so keep the weight to 22 oz. or less for best performance. Regards.
Moeregaard - 16/11/2015
Just finished an electric version of Owen Kampen's Half A Pacer [more pics 005]. I had a set of Ace Wings, so I put them to use. Did not build in the rudder control, as per the 1974 original. Hope to fly it soon.
TomB - 12/10/2017
Thought you might like my take on the Owen Kampen Pacer (oz7186), built for a brushless motor, rather than the original Cox TD 049 (even though I have a couple available!). Flies lovely on a 1000 mAH 3 cell LiPo pulling around 75 watts on a 7" x 5" prop, for around 7 minutes, with the battery only slightly warm at the end of a very spirited flight. [more pics 006, 007]
Roger_Harpenden_UK - 16/01/2019
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