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Mystery Plane

By Oscar Zuniga, EAA 237232, taildrags@hotmail.com

Mystery plane

Beginning with this issue, we’ll be including a new feature. With your help, each issue of Experimenter will present a “Mystery Plane,” challenging readers to determine what the plane is. In addition to this being entertaining, we hope to stir up some renewed interest in these old or unusual yet still viable homebuilt aircraft. Click the image for a larger view of the aircraft and do your best to guess the make and model before scrolling down to find the answer. Then consider submitting a photo and story for future issues of Experimenter.

The aircraft is a classic JN-1, constructed from plans designed by Jim Peris. This plane is perhaps the only JN-1 flying in Spain and maybe even in all of Europe. It belongs to Fernando Abon. He comments that the plans are more of an outline than a step-by-step instruction manual, and he had to do quite a bit of head-scratching to get it built from the plans. He also said that it’s a little slow in roll due to the constant-chord, rather deep wing (7-inch main spars, 4-foot chord). The Barnard M-19 “Flying Squirrel” is based on the JN-1, and many similarities may be seen between the two designs. However, materials and methods used in the M-19 are more conventional, while the JN-1 uses basically “ultralight” construction.

The Peris JN-1: Lost Forever?
It’s understandable when an experimental aircraft designer decides to stop selling plans or kits due to concerns about liability or lack of success or simply for personal reasons. Burt Rutan, John Grega, Jim Bede, and others have made that decision, each for his own reason. It’s quite another thing when an interesting and affordable design is lost due to the death of the designer and the inability of the design to survive the dissolution of his estate. This appears to be the fate of the JN-1, an ultralight/lightplane design by the late Jim Peris of Lancaster, Pennsylvania. Peris died some years ago, leaving the sale and distribution of plans for the JN-1 to his wife, Nancy, who has recently died as well. Investigation into the disposition of the Peris estates hasn’t turned up anything that might lead to continued availability of the plans by sale or transfer of the rights to the design. Unfortunately then, this little airplane may be lost to the homebuilding community.

The best introduction to an airplane comes from its designer. Here are some of Jim Peris’s thoughts about the JN-1 from January of 1984:

Around Christmas, a couple of us were at the house talking airplanes when the idea of a really simple and inexpensive plane came up. Such an airplane could be designed and built affordably if you could scrounge and if you had access to an engine and materials. The experience that I gained from building a Cavalier SA-102, two KR-1s, and a Goldwing was challenged as I went to the drawing board. First, a 10-inch model made from a manila envelope was mocked up and test flown, and it all started there. After looking through engineering and design books, I started to lay out the prototype in full scale. My experience building free-flight scale models was put to work. I had a small garage attached to the house, so keeping up with the concept was a matter of just stepping a few feet away from the house to the shop. In order to build an airplane, I think that you have to work on it or at least look at it once a day or you’ll lose interest quickly. It’s the same concept as kits or models having a picture of the completed item on the box. I kept myself interested by building a nice scale model of the JN-1 with a classy paint job.

Specs 1
Larger view

Specs 2
Larger view

Specs 1
Larger view

The JN-1 was mainly designed for affordable flying, so shopping and experimenting were number one. I built the prototype for $2,500, of which the engine was the single largest cost item at $800. The airplane was designed to operate at ultralight speeds and ranges, take off in 250 feet, land at 28 mph in the same 250 feet, and not require brakes as a result of the low speeds on the ground.

Construction is sheet foam with fiberglass covering. Bulkheads, wing ribs, stabilizers, and rudder are all sheet foam, much like a model airplane which is sheet balsa with tissue covering. For simplicity, everything is as flat or square as possible. Douglas fir was used for the wooden load-carrying members such as the longerons, spars in the wing and tail surfaces, landing gear mounts, and firewall. The foam formers are glassed on both sides, and the fuselage is glassed on the inside before assembly. After assembling the fuselage, the cabin section is then completed and the two sections are joined. Sand lightly and then apply 6-ounce fiberglass cloth with Saf-T-Poxy. The stabilizers and rudder have 1/2-inch x 3/4-inch spars for load carrying and hinge attachment.

The landing gear is a truck leaf spring wrapped with 3-inch fiberglass, and the wheels are from a wheelbarrow. All aluminum angle, tubing, and flat stock are from a local hardware store, as are the control cables and rudder cables, 1/8-inch and 3/32-inch. Pulleys are from screen doors, and the tailwheel is a toolbox wheel. The bearing from a wheel is the mount for the control stick. The wings have two solid spars, and the ribs are foam. The wing is also covered with foam and then glassed. I used 3/4-inch-thick blue foam for the ribs and 3/4-inch-thick white foam for the outer surfaces. A compression strut is installed between the two wing spars at the lift strut area.

Wing struts can come from an old J-3 or something similar. I used 4130 tubing with fittings and attach bolts. All wing fittings on the JN-1 are 4130 steel. The wings have strip ailerons with the control horns attached at the fuselage – a very simple control system.

The seat is a boat seat attached to the crossmember on the bottom of the fuselage. I got a seat cover at the boat shop, and the upholstery is from a fabric shop from their “ends” barrel. Total cost for the interior: 99 cents. My instruments are an auto compass, a self-made ball/bank, cylinder head temperature gauge, altimeter from a parachute, and a tachometer. The airspeed indicator is a rebuilt unit. All the windows and windshield are plexiglass from the hardware store, and the slight curve in the windshield is no problem to install.

The wings fold down in front and then swing back from universal joints at the drag spar attach fittings. The tail folds up on piano hinges. All control cables are fed through nylon tubes that are glued into foam formers, making for very positive guides. I used AN bolts and leftovers from other builders, costing about $150 in hardware. I used Morton’s body fill for glass fill on the top surfaces only, and acrylic enamel with hardener for the paint.

The Kawasaki 440 isn’t the only engine that could fly the JN-1. It does okay, but it could use any engine up to 50 hp – just beef up the firewall a little and make allowances for weight and balance. You have a couple of inches beyond the rudder pedals to shift the firewall if needed. I now have a 5-gallon fuel tank installed, but it could be larger if so desired. There’s a minor amount of welding to do in construction, but mainly just 4130 pieces such as the stabilizer stiffeners, drag spar universal joint, and the wing strut fittings. The wheel pants are white foam shaped by hand. Two layers of fiberglass are laid up, then hollowed out except for the nose and tail, which are left intact to keep mud out. Wooden blocks are glassed into designated positions for bolt mounts. Each wheel pant weighs 2-1/2 pounds complete. The build time for the entire airplane is dependent on the amount of experience and tools available, but 500 hours seems to be about average.

The one good thing about an experimental aircraft is the repairman certificate that can be obtained by the original builder when the plane is inspected and test time is flown off. After final inspection, you can do all condition inspections yourself and save more money over the life of the airplane. It’s very gratifying to build and maintain your own special aircraft.

I didn’t go for any high-tech sort of plane; this one was fun to design and build. Really a very inexpensive hobby! I guess you could spend $2,500 in a couple of years playing golf or bowling. The test flight was a couple of hours long, and we had a lot of fun with a J-4 Cub and a Vagabond, all flying formation and taking pictures. It flies very stable, no bad habits, and cruises 55 to 60 mph. Takeoff is in 250 feet with climbout at 40 mph. Rate of climb is 600 feet/minute. Approach at 40 mph and land at about 28 mph. All speeds are indicated.

Qualifications
I come from an aircraft family. My father was an A&E and A&I for some 55 years. I also have a brother who is an A&E and private pilot; he and I built model airplanes since 1930 and built everything possible. My flying experience has mainly been as a private pilot. I have owned a J-2 Cub, a Swift, an Aeronca Champ, a Cessna 172, and a Culver Cadet.In addition to a Cavalier SA-102, two KR-1s, a Goldwing, and the JN-1, I’ve built a Fisher 404, and I’m now designing a two-place and a ducted fan scale ultralight jet.

I was an engineer gunner on B-24s in the China-Burma-India theater in World War II. I’m an EAA tech counselor, EAA member number 1418, and I’ve served as president of EAA Chapter 540 (Smoketown, Pennsylvania) for three terms.

– Jim Peris

 
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