Wicks Aircraft Bobcat ultralight, Wicks Aircraft, Supercat experimental aircraft, Wicks Aircraft Bobcat, Supercat experimental light sport aircraft (ELSA), Lightsport Aircraft Pilot News newsmagazine.

Lightsport Aircraft Pilot is a directory of aircraft that generally fit into what are described as ultralight, advanced ultralight, lightsport aircraft, experimental light sport aircraft, experimental aircraft, amateur built aircraft, ELSA or homebuilt aircraft in the United States and Canada. These include weight shift aircraft, more commonly known as trikes, powered parachutes, and powered para-gliders.

Wicks Aircraft Bobcat, Supercat ultralight, experimental, amateur built aircraft.

Supercat ultralight aircraft Cat Scratches     
Issue #8
 December 1987 The Bobcat Newsletter

Hello again to all of our Bobcat-Supercat builders out there. I'm happy to report that business is still going on.

This past summer was quite slow but as winter isapproaching it has picked up quite a bit. We now have shipped about 240 kits and close to 700 sets of construction drawings worldwide with a reported 60 aircraft completed and flying.

An accumulated flying time of several thousand hours seems to have proven the integrity of the basic design. Several of our overseas builders are now enjoying flying their projects and a couple are featured in this issue. We will attempt to get this issue out to all 700 builders even though we only have about 250 paid subscriptions.

The newsletter is quite important as it is the only means we have of communicating and sharing of ideas and problems. I will again ask for contributions from you whether it be hints or complete stories.
Let's hear from you!!

We have had some problems with subscriptions since we switched to using a computer for our mailing lists and for this we apologise. The old adage of "garbage in-garbage out" seems to be holding true for us as well. If you have paid for four issues and did not receive them, please let us know. There have been several important intems in the past couple of issues that I'm sure you would want to know about including a sample weight and balance and flight manual in issue #7. A $12.00 subscription ($16.00 overseas) entitles you to the next four issues. 

Bobcat - Supercat
Empty Weight: 325 lbs.
Gross Weight: 650 lbs.
Wing Span: 27.2 ft.
Wing Area: 108 sq. ft..
Engine: 447 Rotax
Cruise Speed: 70 mph.
Stall Speed: 27 mph.
VNE: 85 mph.
Construction: wood and fabric
Building time: 400 hours.

 We sincerely hope all of you will subscribe. Back issues are available for $3.00 per copy.

Both Kay and I made the annual trip to Oshkosh this year and very much enjoyed the show and meeting with our friends. The first two or three days were almost unbearably hot but it cooled down later in the week and turned out to be one of the best conventions yet.  The "Cat" flew hard every day. I now have tached about 180 hours on this aircraft which is much less than I would like but it seems there is never enough time to go out and have fun. I did install my side doors recently as cold weather has finally hit Arkansas. The doors keep me qite comfortable down to about 30 degrees outsid air temperatoure so I have still not installed cabin heat. Tempertures here in our part of the country seldom are below 30 degrees.


Although only a few of you are using the Ultra-Prop, I thought I would include the following service bulletin from Competition Aircraft so you would be aware of the problem.


Historically, propeller spinners have been plagued with problems. Almost every aircraft manufacturer has had difficulties with cracks and departing spinners because of the enormous vibration energy at this piont.  Service bulletins and "improved spinner assemblies" are common in the industry. Every hole and cutout in a spinner or its bulkheads invites stress cracks.

Despite our best effortst o make the polyester spinner installation on the Ultra-Prop 100% positive, a few reports of spinners coming off tractor installions and damaging the blades leads us to issue this service bulletin. The spinner should not be used on tractor installations. If it comes off, the blade damage could affect the ultralight's performance during a critical phase of flight.

On pusher installations, the pilot must make his own decision with regard to installation of the spinner. Tests have shown no damage caused by a departing spinner. Ultra-Prop kits will continue to be shipped with a spinner, since we don't know how it will be installed.

All owers of record who have returned the Owner's Warranty card have been advised of this service information.

Additional product or service information can be obtained by calling or writing Competition Aircraft at 11110 Gopher Mine Trail, Grass Valley, CA 95949. (916)268-3048.

Spinner Solutions

Now that the service bulletin on Competition Aircraft's spinner problem has been printed, I will relate some of our own problems with spun aluminum spinners. As most of you may know, the company that manufactured these aluminum spinners has withdrawn them from the market as most all the units experienced cracking after a short time. I personally went through four of them in about a year of use. Not only were they fairly expensive ($50 each) but were also very time consuming to cut and fit around the prop hub. It would take me an aveage of 3 to 4 tedious hours to cut, sand and very carefully polish the cutouts to eliminate possible vibration cracks. even with all that attention, a couple of them only lasted a few hours before coming completely apart. The aluminum back plate also was prone to cracking around the prop bolt holes although we eventually found a solution to that problem.

Well folks, we have finally come up with a spinner unit that works well and, although not exactly cheap, is less expensive than the aluminum cones. the major problem with the spinners has been the lack of a front stabilizing bulkhead but due to the variety of propeller thicknesses it was virtually impossible to manufacture enough different sized bulkheads to accomodate all of them.

The solution we finally devised is illustrated in the following sketch. A one inch O.D. aluminum tube is permanently mounted in the nose of the spiner and when the cone is installed over the prop, this tube protrudes though the 1" I.D. hole in the prop flange and prop. This virtually eliminates the nose cone "wobble" which was causing the vibration cracking.  

The spinner and backplate are molded from high strength ABS plastic and are more resistant to vibration cracking than the spun aluminum. Note the .050 aluminum backing plate circle used to reinforce the the backing plate. The backing and reinforcement plate are provided with the 1" hole already drilled for different configurations. the nose cone is attached to the backing plate with 3/16" AN stainless steel screws, AN washers and AN lock nuts. These are all prvided in the kit along with complete instructions. The nose cone will accept most any type of paint. Price for the complete spinner kit is $40. 

Fuel Funnel

A really handy item which some of you may not know about is a fuel/water separator funnel appropriately named "Mr. Funnel". Introduced at Sun-N-Fun a few years ago it is an item I can't seem to do without. I never put gas in my tank unless it goes though this gadget. It utilizes a special thrmoplastic coated stainless steel base with a hydrophobic mesh separator membrane that has an affinity for petroleum but repels water. Whew!! Despite the fancy nomenclature it works beautifully.

Along with the fact that fiberglass tanks are much less likely to collect condensation diligent use of this funnel should dramatically reduce the possibility of water contamintion in the fuel system. There are two sizes available on the market but the smaller one (5 1/2" bowl diameter) is your best bet. They cost around $10 and are well worth the investment. Wicks Aircraft Supply as well as most other aircraft parts houses have them in stock. To my knowledge, I've never had a fuel contamination problem while using this system. Incidentally, while on the subject of fuel, I have noticed that lower cylinder head temperature readings using regular leaded gas than I do with the higher priced unleaded.

Test Flight

I recently had the pleasure of test flying a supercat built by Dr. Robert Yoak from Benton, Kentucky. After a hospitable invitation from the good doctor, Kay and I drove over on a weekend and really had a good time. Doc's plane is powered with a 447 which started up very nicely and ran well though the two or three short flights I made in it. Flight characteristics were very similar to our prototype but there were a couple of exceptions which prompted the writing of this article.

Upon close examination of the plane, I found a discrepancy in the tail surface flying wires that might be worthy of mention here. The two aluminum tangs that connect the bottom horizontal stabilizer flying wires to the fuselage bracket "E" as shown on plate #10 of the construction drawings were installed incorrectly. After looking at the plans again, I can see how the mistake could easily be made. Dr. Yoak had both of the tangs installed on the top side which produces an uneven pull on the "E" bracket. I had intended that one of the tangs should be on the top and the other one on the bottom to produce an even pulling force. This may not be a critical point but the tangs should be installed correctly to insure even pressures.

Hopefully, the sketch on the following page will show how this installation should be done. 

The one thing that really caught my attention in test flying this plane was the fact that I had absolutely no ground steering control! It became immediately obvious as I started taxiing out to the runway. The only directional control I had was with differential braking. Rudder pedal input had no effect. We played a bit with the springs that he had attached to the rudder horn and the tail wheel control arm but with no success at all. I thought that we could stretch the springs enough that the tail wheel would move when rudder was applied but no matter how tight they were stretched, the tail wheel would not respond. I had heard of this complaint fron other builders but didn't realize the extent of the problem until I actually tried to ground steer one of these puppies with the "tension only" type springs. It just simply can't be done!

The "fix" which I've been using all along (and failed to pass along in the newsletter) is the use of the type of spring employed by the "big boys" . Instead of tension, it is a compression spring. they are available in most good hardware stores and are sold as aluminum screen door springs (usually in a repair kit). The sketch on the following page illustrates what they look like. Short sections of small chain and "S" hooks are used to connect the springs to the rudder horn and the steering arm. The chains are used for tension adjustment. 

The springs should be quite tight to give adequate ground steering control. An advantage that might not be immediately ovious is that using this type of spring eliminates concern over breakage of the spring connection. If it does break, directional control may be sloppy but not totally lost.

At any rate, by holding the brakes and applying full power, I was able to get Doc's plane in the air from a grass runway adjoining the paved surface. At full power the rudder takes over immediately and provided enought directional control to fly off grass. But please do as I say and not as I do! Don't attempt test flying without adequate ground steering. Set up correctly these Cats exhibit really easy ground steering but can be a real bear if not done properly.

One other note on Dr. Yoak's plane.When I flew it, he had not yet installed the aileron gap seals so I didn't know what to expect for roll control. I was a bit concerned on the first test flight but the ailerons seen to work just fine. Hope the Doc won't think I'm being too critical of his project as I think that with a few adjustments it will prove to be an excellent flyer.


Very little news to pass along about Rotax engines in this newsletter but a couple of things might be of interest. A good friend of mine that flys a Weedhopper(?) with a 277 Rotax has had some problems with the pins that keep the carburetor floats in position. He has had to replace both the pins and floats after a reported several hundred hours of flying time. Apparently, vibration is again the culprit causing the wear. The steel pins were extremely worn as well as the tube manufactured inside the floats. I tend to think the engine installation in the weedhopper allows much more vibration than our "Cat" mounts but it caused enough concern that I pulled the float bowl off mine just to check it. Our's showed no wear so I snapped the float bowl back on but I will try to check it as we accumulate more flying time.

Another thing I learned of only recently is that Rotax does not recommend scraping carbon buildup from the cylinder heads every 100 operational hours as reported in one of our recent newsletters. Apparently, if you are using synthetic oil such as Bel-Ray, very little carbon buildup occurs and the chance of a piece of carbon droping into the cylinders and getting between the ring and piston when you are scraping could cause more damage than if left alone. You still may want to pull the head every 100 hours or so and check the carbon just to be certain.  

We are mixing the Bel-Ray at 60 to 1 per Rotax Suggestions and find that it works just fine. If you do use Bel-Ray, it's much less expensive if you buy it by the gallon. We try to keep it in stock, Price is $22.00 per gallon.

A Determined Pilot!!

I've been intending to write about Charlie Curtis from Millington, Tennessee and his Supercat project for some time now and I suppose this is as good a time as any. Charlie's story is a bit different as he has a physical obstacle to overcome that I'm sure most of us would find insurmountable. He is a paraplegic due to a motorcycle accident several years ago and is confined to a wheel chair for motivation.

before his accident, he was a pilot and in recent years has taken up the fine sport of radio control model airplanes to satisfy his flying urge. He became interested in the Bobcat a couple of years ago and decided that he wanted to build one in large part to the fact that it appeared to be a large model airplane. His courage and determination should be an inspiration to us all.

Charlie has completed his project and the test flying date should be arriving shortly. He asked me to fly the plane initially since we are located not far from him. I got a call from him the other day expecting to hear it was ready but of all the luck, his house had burned down and was a total loss though his plane was not damaged. As soon as he gets situated again, I expect to hear from him and will be more than happy to make the test flights.

You may not be able to determine from the picture of his cat on page 5, but he has cut off a portion of the inboard section of the aileron which enables him to pull his wheel chair up to the rear spar of the wing. A small section of the right hand portion of the cockpit side wall folds down and provides him entrance to the cockpit. Rudder control is via a hand operated stick although the stock rudder pedals are left intact allowing normal operation. I have not personally seen the aircraft but it looks really well built in the pictures. Power is a Rotax 447 and the plane has all the latest modifications.

            Bowdler Aviation, Inc.
            1370 Howell Rd.
            Beavercreek, OH 45434-6828
            Manufacturer no longer in business.
Newsletter for Bobcat and Supercat builders. I do have all of the old newsletters and copies are available at: kenneth@tctelco.net 

Wicks Aircraft Bobcat ultralight, Wicks Aircraft, Supercat experimental aircraft, Wicks Aircraft Bobcat, Supercat experimental light sport aircraft (ELSA), Lightsport Aircraft Pilot News newsmagazine.
Wicks Aircraft Bobcat, Supercat ultralight - experimental lightsport aircraft


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