Propo-Cat (oz14026)

 

Propo-Cat (oz14026) by Bud Atkinson 1966 - plan thumbnail

About this Plan

Propo-Cat. Radio control aerobatic model. WIngspan 60 in.

Quote: "Bud's Class Two Radio Control Craft. Kansas City cutie takes proportional or reed R/C equipment, has sleek look of hot low-wing Multi types, forgiving qualities of a gentle yet well-trained kitten. Propo-Cat, by Bud Atkinson.

The name Propo-Cat stands for a proportional control R/C tigercat, as I designed it around desirable features of proportions. However, you reed flyers needn't despair. A fellow KCRC'er built and flew one with reeds with very good results; of course, not as smooth as propo, but performance was very good.

Class II contest ships are as Class I and III airplanes, similar in appearance and layout with each designer adding, his own touches, but we do believe the Propo-Cat to be somewhat different in conception and also in construction. I always have tried to have a reason in my designing and not change just for the sake of change or appearance. I won't go into a lot of aeronautical double talk, but I believe most model designing is nothing but the results of past experience plus trial and error, and so it was with the Propo-Cat.

In all fairness much credit should go to my Aristo-Cat (oz6995) since a great deal was learned from it. A designer always picks up knowledge from his previous designs be it good or bad, and there never has been - nor will be - a perfect airplane be it I, II or III.

The first thing noted about the Propo-Cat is the landing gear, not necessarily a new idea, but I think unique on Class II ships. In the Middlewest we do have wind. The majority of the flying fields at contests are grass or something just as bad. This, no doubt, is the case throughout the rest of the country except where flyers are fortunate enough to have the use of abandoned air fields.

The gear in the wing, as in a low winger, will stay right side up on rough flying sites as well as in wind which is always a problem with Class I and II shoulder or high wing airplanes. The extra length of main gear also takes much of the shock out of landing. The main gear gives the appearance: of 'walking-off' instead of flying off rough take-off strips. At the '65 Nats the Navy judges were much impressed with the smoothness of the landings and touch-and-go's of the Propo-Cat; she never received less than a 4 on touch-and-go's and landings.

I believe you will find Propo-Cat easy to build and fly, being more of an advanced Class II airplane with cleaner lines than most of the Class II today. The touch-and-go's and landings are a joy to behold!

You will notice on the plans that the fuselage sides are 3/16 sheet. No, this is not a mistake! By using 3/16 you no longer need doublers as such. It also gives needed strength at the leading edge of the stab where so many airplanes are weak; the extra weight, which is small, is well worth it.

The wing saddle is of 1/8 ply. I use white glue to assure a straight wing saddle. The rest of the fuselage construction is standard practice. The wing and stab are set at zero degree incidence and care should be taken to maintain this. The engine is set at 3/8 in downthrust with 3/16 in sidethrust. Lighten all blocks to keep weight down.

No servo location is indicated since with proportional and reeds there are several types and sizes of servos. I have used the F&M proportional rig in two Propo-Cats, the early model using the metal Bonner servos. The F&M has worked very good for me and the Propo-Cat but, of course, any proportional or reed gear will fit in the fuselage nicely.

The wing on a Class II airplane, critical as far as performance is concerned, must be straight and true. I built two wings, one all wood and one Styrofoam. As far as flying goes there was no difference, but foam wings are much truer and will stay that way. Care should be taken to insure a true straight wing if you build an all-wood wing.

The main landing gear is installed the same as you would any low winger. Care should be taken when you glue the landing gear blocks in place since the extra length of the gear does put a little more strain on the blocks.

On the plans, I show 3/16 wire for main gear, but if you are a light builder 5/32 wire is sufficient, 6 to 6-1/2 pounds. I would say to use 3/16 wire if you go over 6-1/2 pounds. I have used both with good results. My Nats Propo-Cat checked out at 6-1/4 pounds and I was using the 5/32 wire main gear; nose gear is standard 5/32 wire.

Select 3/32 sheet for wing planking to keep weight down. For better rolls on Class II, the wing loading must be kept to a minimum.

The stab is easy to build, and strong, no trouble should be encountered; in making the stab use hard 1/16 sheet for covering and soft balsa for ribs. The fin and rudder are of hard 1/4 in sheet to keep from warping. Great care should be taken in building the fin and rudder. A Class II airplane is only as good as the trueness of its fin and rudder - the rudder being most sensitive since it must have a lot to accomplish. Do not cover elevators or rudder with silk, use tissue, as silk will cause them to warp.

I believe I have covered the high points of the Propo-Cat's construction, with the rest being standard building practice. Sandpaper and elbow grease are the by-word in any good airplane. I believe you will enjoy building the Propo-Cat. Your model will draw favorable comments at the old flying patch on the ground with its appearance as well as in the air through its performance."

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Update 23/8/202: Added article, thanks to RFJ.

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Article.

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Propo-Cat (oz14026) by Bud Atkinson 1966 - model pic

Datafile:
  • (oz14026)
    Propo-Cat
    by Bud Atkinson
    from American Modeler
    March 1966 
    60in span
    IC R/C
    clean :)
    all formers complete :)
    got article :)
  • Submitted: 12/08/2022
    Filesize: 797KB
    Format: • PDFbitmap
    Credit*: dfritzke
    Downloads: 398

Propo-Cat (oz14026) by Bud Atkinson 1966 - pic 003.jpg
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User comments

Another 'hidden gem' here, I think. And this for both, the model and its designer.
Hubert - 23/08/2022
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