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One Design News

ONE DESIGN NEWS

Volume 1 Issue 2 • January/February 1995


A Bimonthly Publication for Builders, Pilots, and
Enthusiasts of the ONE DESIGN Series

I must start issue # two of the ONE DESIGN NEWS by thanking all of you who have subscribed to the newsletter, as of February over 170 people have returned the form. Many of you had comments and observations, ranging everywhere from technical advice to “how about a swimsuit issue.” Some of the more repeated comments include, a plans revision section, a tips section, include lots of info and pictures of builders projects, and the number one request, to publish a list of builder’s names, address, and phone numbers. This last request presents a problem. I should have provided a spot on the subscription form asking if you mind your address and number published. I realize that is can be great benefit to builders or even prospective builders to contact others in their area, to exchange information, compare projects, and share material, however, I hesitate to publish names without prior permission. I think that a compromise would be to wait until the next issue to include a subscriber list, and if you do not want your name in the list please let me know beforehand. I will not include names of plans holders who have not subscribes, merely because they have not seen this notice. I hope this works.

I have encountered another problem that I did not anticipate, I have had a hard time deciding where to cut this issue off. I have received some great information, and photos from builders. Please do not take this to mean that I am not encouraging future submissions. I could easily have produced a fifteen page newsletter, and I hope to have this much information for each issue. To my knowledge there are at least fifty serious builders, which means that by fall of this year we should see some aircraft flying. There is some great work being done on ONE DESIGN projects, and this is just the beginning.

IAC ONE DESIGN NEWSLETTER

Dan Rihn has written his last issue of his original newsletter dated vol 2, # 6. Dan produced this newsletter to keep builders and others up to date with plans progress, and the ONE DESIGN category. However as it is now redundant, Dan gets a well deserved break. This original newsletter certainly served its purpose, and really helped keep the interest level high. Dan will continue to be a regular contributor to the ONE DESIGN NEWS.

PLANS UPDATE

Part three of the drawings are due to be released shortly, this will be the final set of drawings. There may be additions, error correction, or clarification of existing information, but all of these will be included in future issues of this newsletter.

ONE DESIGN RULES

The ONE DESIGN rules were published in the December issue of Sport Aerobatics. The rules have been an ongoing subject of discussion and for some, dispute. I would really like to see the concept work, and I imagine many others also would. When the original concept was introduced in Sport Aerobatics it generated an amazing amount of mail. I must admit that there has been a fairly even split in the comments received to date, but here is also a large group of people building what they feel is a magnificent aircraft, with little consideration to the concept. There will certainly be enough ONE DESIGN aircraft to hold a competition within two years, however, will they all be red, white, and blue? Time will tell.

ONE DESIGN WING – A construction overview, Part II

We left off in issue one with a complete wing skeleton, glued together, but without stringers, or fittings.

We decided very early in the project that with 128 individual stringer cutouts we had better devise a way to do them quickly and accurately, if you intend to approach them with a coping saw and a straightedge you had better book a couple of days off. We built a small jog for a router to ride in. You will need a sharp ½” end cut router bit, we have tried both straight flute and spiral flute, and although the spiral flute cuts marginally better with less breakout, they are very expensive. I would think that you might be better off purchasing two straight flute end cut bits, and if the first shows any sign of getting dull, switch to the other, remember 128 slots! We used an 8” by 9’ strip of ¼” plywood as the base of our jig. We added ¾” square runners along each side. This enables the router base to follow along the runner, and as it is circular there is no particular alignment necessary. We then determined where each rib was located along the length of the jig, and made about a 3” notch along the jig with the router, we then clamp the jig along each respective stringer line using the tip rib and the base rib stringer notches as a guide, and then by running the router down the jog along the runner you get an exact stringer line. We have found that it is better to make two passes long each line, once at 3/8ths, and another at the finish depth of 5/8ths, this minimizes the tearout at each gusset. Along the nose ribs we leave the stringers slightly proud ,and finish sand with a long board to maintain the correct contour.

Installing the fittings is pretty straightforward, we use all machined components for the aileron hinges and drive fittings. Make sure you install plywood crush plates between the fittings and the spars. The bellcrank errors are covered in this issue elsewhere. It is very important to maintain alignment between the three aileron hinges because misalignment can cause bindig, and because over a 6 foot aileron incorrect alignment will be very noticeable. I would recommend that you align and drill the rear spar for the hinges on a drill press before you assemble the wing.

We have also added tie down fittings in the wing, these are attached to the main spar at station #84. The fittings are a simple machined strap with a 3/8ths female thread mounted flush with the bottom skin, we have removable 3/8ths male thread eye fittings. I imagine there will be lots of variations on this idea, (I have already seen four different types). We have mounted the pitot system at both the location shown on the plans, and in one wing we mounted the pitot block on the outside of the tip rib, this means that if it ever gets bumped, and they do, we still have access to the block and the fitting. We mount the static source on the fuselage. Make sure that you varnish under all fittings, and use large 970 washers up against wood, or even better a 4130 crush plate, and anchor nuts. Next issue, sanding, skinning, and ailerons.

A SPAR CLAMPED AND GLUED IN THE JIG

THE STRINGERS IN PLACE

WING CONSTRUCTION – ANOTHER PERSPECTIVE

My name is Christopher Gardner. The new editor of this newsletter, Peter Groves, has asked that I write an article discussing a second viewpoint on wing construction techniques. Some of you may recognize my name from my participation in the prototype One Design program; in addition, I have over nine years experience as an A & P involved in the maintenance and manufacture of aircraft ranging from homebuilts to transport category jets.

Because the very nature of this aircraft deals with construction from raw materials and blueprints only, I feel it is incumbent upon any potential builder to familiarize him/herself with basic woodworking practices available in books from a number of sources, two of which are the FAA’s AC 43-13 and the EAA’s Wood/EAA Aircraft Building Techniques. With this in mind, this article will concentrate on details of One Design wing construction only.

One question all builders are faced with at the beginning of any project concerns the type and quantity of equipment needed to accomplish the job. The following is a brief list of equipment I consider essential to construction of this wing:

  • 18 ft long x 4 ft wide flat table top
  • 8 point water level system (about 30 ft of ½ inch clear vinyl Tubing and some “T” fittings
  • Clamps. You cannot have too many clamps. 2 x 4 Block and Allthread Clamps (more about this in spar section);
    C-Clamps (at least 11 each of 4” capacity);
    Spring clamps (10 or 12 each of 1 in and 2 in capacity)
  • 10 ft angle iron straight edge or equivalent
  • 24-in x 16-in carpenters square
  • 12-in combination square
  • Chalk line
  • 7-1/4 in Circular saw
  • Hand jig saw
  • Electric or pneumatic hand drill and drill bits
  • 3 in x 6 ft minimum sanding block (straight and absolutely flat)
  • Fine wire staple gun and ½ in x .033 chisel point wire staples
  • 10 in hand place
  • Dust mask/respirator

While not essential, the following make the task significantly easier:

  • 6 in motorized jointer
  • Table mounted combination of disk and belt sander
  • Air compressor (if pneumatic tools used)

We start with fabrication of the main spar, which utilizes douglas fir. The stock we found was already mill cut to ¾ in x 4, 6, and 8 in. dimensions, with a radiused edge on the boards. This requires squaring the edge of the boards on a jointer to remover the radius. Next we cut each of the boards to the proper length and dry assemble the spar so that the grain slope on each lamination is opposite the successive lamination, and each butt joint is staggered on successive lamination. We then cut the spar stack so that each of the lamination layers has the same overall width of 9.75 in. Before disassembly, we match mark the boards in sequence to facilitate reassembly and mark the profile for the scallop cutout at the ends of the boards. After disassembly, we cut out the scallop profiles with a hand-held jog saw and sand the edges smooth. Although our spar assembly jig is straight-forwards and inexpensive to make, it is constructed of item #1 in the essential equipment list, the 18-foot x 4-foot table. This table is the foundation of all the wing construction, and as such, it must be reasonably flat and dimensionally stable. As can be seen in the accompanying photos, ours are constructed from ¾-inch x 4-foot x 8-foot plywood, 1-inch x 6-inch x 8-foot side boards, a few 2-inch x 4-inch x 4-foot brace boards on bottom, and several pre-fab steel table legs with adjustable screw feet installed at their base for leveling. We leveled ours with a builder’s transit, but any method including simple line levels, etc will do. One top of this table, we install our spar jig which is fabricated from 1-inch x 6-foot boards and plywood end gussets. They are simple “L” shaped platforms with triangle gussets on the ends for rigidity. We place a platform at each end of the table 17.5 inches apart. Placing household door shim stock under each platform, we level the end platforms and screw them to the table top. We then string two lines of fluorescent fishing line taughtly between these platforms on each outside top edge. We finish the jig by placing eight additional platforms equally spaced between the ends and shim to flush with the bottom of the strings and secure each platforms to the table with screws. This provides an elevated true surface with clearance for the clamps used during spar assembly.

In regards to these clamps, ours are made from 2 x 4’ yellow pine boards with 5/8 inch allthread secured through holds in the outer ends of the boards. We tack welded a nut to one end of the allthread, with the other nut free spinning. As can be seen in the photo, these clamps are positioned so that we can provide clamp pressure for both the laminations and the butt joints simultaneously. A word of caution, this incorporates two steps into one, and with a finite amount of epoxy working life and large surface areas to cover, speed is of the essence. A minimum of two people are required during this stage. Also, don’t forget to apply a layer of wax paper or equivalent between the clamps and spar surfaces to avoid the obvious.

At this point, we have a rectangular spar blank ready for tapering and beveling. This is accomplished by first marking a centerline on the spar forward face with a chalkline. Next we transfer the measurements for the spar’s height at the root rib and tip rib locations using our centerline for reference, and mark these heights on the spar. This gives us the taper profile of the spar. We use a circular saw and a long straightedge to rip cut both the spar taper and bevel simultaneously. We position and clamp our 10-foot angle iron straight edge an exact distance from the profile marks to allow for the width of our circular saw base plate which will be following the straight edge. We adjust the saw base plate to the proper 4.5 degree bevel angle, and make the cut. This procedure is performed four times, for each of the two top and two bottom surfaces of the spar. This completes the fabrication of the main spar.

We manufacture our ribs with production templates used to router out multiple pieces; however, the same things can be accomplished with a jig saw and patience. Pre-assembly of the ribs is limited to gluing the capstrips, center vertical stiffeners, and center gussets in place on both main and nose ribs. The forward and rear verticals and gussets are not installed at this time; however, we use a table-mounted 8-inch disk sander with an adjustable platen to sand the angles into the nose rib forward edge and main rib trailing edge surfaces prior to rib installation. Incidentally, we use production truss rib style fixtures for building the ribs, but again these could all be built free hand with some extra effort and care. At this point, I want to mention a real time saver for which I feel the cost is justifiable. Instead of using wire nails for assembling various rib parts, etc., during construction, we purchased a pneumatic fine wire staple gun manufactured by ITW Paslode for approximately $180.00. This tool speeds construction considerably (important when working with epoxy) and greatly reduces the effort expended. Sometimes tools just have to be viewed as investments, and no, I don’t own any ITW stock.

After Rib assembly, we place the main spar atop our construction table, level it at the tips with our water level and vertically at its forward face with an electronic level (or bubble level) and clamp in place to three “L” brackets at the center and tips. By now, we have also precut the forward and rear spars including the tapers and bevels, using the same method as described for the main spar. We then position these spars at the proper distance from the main spar at the root and tip rib locations, and using the premarked centerlines and water level, level them to the main spar centerline and clamp in place two more “L” brackets. Next, we mark the spars at the appropriate wing stations for rib locations, squaring off the centerlines. We glue one forward and rear vertical support to the face of the spars for the nose and main ribs. The forward and rear spar rib verticals need appropriate bevels cut or sanded into them before installation. Now the ribs themselves can be installed, including the remaining vertical supports and forward and rear gussets. Throughout these steps, we use the staple gun and spring clamps mentioned earlier for pressure while gluing verticals and gussets. After all the ribs are installed, we have two steps left before skins can be applied. First, the capstrips must be block sanded so that the tops of the ribs mate smoothly to the top surfaces of the spars. We use a long six foot x 3 inch wide block sander to accomplish this task. Working back and forth and fore and aft across the wing with 100 grit paper glued to the sanding block, we slowly sand the taper into the capstrips where they meet the front and main spars, and gradually blend them back to the straight rear spar. Second, the stringers must be installed. We begin by marking the locations of each of the eight stringers on the root and tip ribs, and using our long angle iron straight edge, mark across the top of the capstrips between those two ribs. We cut the appropriate angles into our stringers on our six inch jointer, and using a piece cut from the excess on the end of each stringer, mark the stringer profile on the gussets by simply flushing the top of the stringer against the top of the gusset. Using a hand held jog saw with an adjustable show, we set the angle required to cut across the capstrips and cut down into the gusset/capstrip along the profile lines. We use a coarse file to make a snug fit, then glue the stringers I place.

Up to this point the wing has been constructed inverted with the bottom surface facing up. This is desirable for a couple of reasons. Once the bottom skins are on and the wing flipped over in the jig, it is easier to locate the hole for the access panel below the aileron bellcrank, as well as locating the aileron pushrod penetration path. So, we install bottom skins first. We place a skin panel atop the structure as far forward as possible without coming across the rear spar with the aft edge of the panel. Our skin splice will run parallel to and immediately aft of the rear spar. We square the inboard edge of the skin with the nose rib and a reference mark on the rear spar. Next, we mark the locations of the outside edge of the tip rib, the aileron well area, all ribs, spars, and stringers. We then transfer these marks to the outside of the panel and cut out the aileron well area. The excess cut off from the aileron well provides sufficient material to cover the inboard trailing edge area. This layout pattern leaves between 1-1/2 and 8 inches of excess along the front of the panel. We leave this attached to assist in bending the skin around the nose rib curvature. After soaking the leading edge of the skin in water overnight, we tack the skin to the structure at the main spar and first stringer aft of the main spar with wooden tack strips. By screwing an 8-foot 2 x 4 to the excess on the top surface of the leading edge, we provide a bearing surface to apply clamp pressure to bend and hold the skin firmly in place over the nose ribs. Using an iron, we apply head to the water-soaked areas and generate steam to soften and form the skin. We leave the panels for 24 hours to assure complete drying. The skins are now ready to be glued to the structure. As can be seen from the photos, we use tack strips to secure the skins to the structure while the epoxy sets. Finally, we remove the tack strips and trim the excess from the leading edge.

After turning the wing over, re-levelling, and clamping in place, the bellcrank brackets and other interior components are installed. The method for top skin installation is identical to that for the bottom with the exception of having to seal the interior surface of the skin with epoxy or varnish in all areas except where wood to wood contact occurs. This is easily accomplished by again marking all the spars, ribs, etc., masking those areas off, and paining all remaining exposed surfaces. During the wing skinning stages, we use a home room humidifier to artificially increase the moisture content of the air. This in turn allows the skins o absorb some of the moisture which swells them slightly. When the skin returns to normal moisture content, they will be tight and wrinkle free on the structure. In closing, I would like to add two things. First, no matter how uncomfortable it is, always use a good quality dust mask/respirator when sanding epoxied parts. And last, the preceding information is but another technique of wing construction for the One Design. The method that works for us may or may not be suitable to your needs. In any case, we all benefit from the exchange of ideas, and I hope this article contributes to the success of your project.

CHRIS GARDNERS’S WING UNDER ASSEMBLY

THE WING AFTER SKINNING



ONE DESIGN VS G200

By Lloyd Beaule

I flew both of these aircraft about a month apart. Comparisons are inevitable, but it is important to point out that neither of these designs was in its final configuration when I flew them.

The One Design had a 320 cubic-inch, 160 horsepower engine with fixed-pitch prop, but will eventually sport a parallel-valve 180+ horsepower Lycoming. It will also have a slightly enlarged vertical tail / rudder on all the models other than the prototype. The G-200 is pulled by the esteemed 10-360 angle-valve 200 horsepower Lycoming, with MT composite constant-speed propeller. This is the final engine/propeller combination, but other features are not necessarily so.

Near the leading edge of the G-200 wing, there was a forest of tiny vortex-generators that went from tip-to-root, both top and bottom. The airplane is still being tested, which is not surprising; it’s a prototype. It is doubtful that such delicate little vanes would live there permanently. But who knows; let’s wait and see.

ONE DESIGNG-200
Wing Span19.3 feet20 feet
Length17.2 feet17.75 feet
Wing Area74.6 sq ft75 sq ft
Aileron Span73% of trailing edge100% of trailing edge
Empty Weight740 lbs (prototype)840 lbs (prototype)
Load Limit+/-10g+/-12g
Stall Speed60 mph60 mph
Max Speed220 mph236 mph
Roll Rate360 deg/sec360 deg/sec +
Seats11

The numbers listed above are not necessarily dead-on. They have been in flux for a while, so it is difficult to pin down the final figures, but they are close. The biggest difference is weight. Richard Giles says the prototype has “extras” on it, and a lightweight G-200 is easily done.

Construction Welded Chrome-moly tube fuselage and tail group. Wire-braced horizontal tail. All wood wing. Ailerons wood frame, fabric covered. Built entirely of Advanced Composites. Wing skins built of pre-preg carbon filler and Nomex honeycomb cores. The spar has S-glass in the shear webs and uni-directional graphite in the caps.
Wing Swept leading and trailing edges. Tapered in thickness and plan form. Similar to Laser, Sukhoi Sno-cone Swept leading edge only. Trailing edge is straight (but looks swept in the air). Tapered in thickness and plan form. Sno-cone
Seat Semi-supine, adjustable. Seat is perfect for me. Seat is laid well-back, and located high in the fuselage. Not good for me. Seat installation is an option, though.
Taxi, T/O Landing Very Pitts-like, but easier. No tail-wheel cable to mess with. Outstanding visibility for taxi, takeoff and landing. Locking cable to mess with.
Climb Modest 2000 fpm Good 2500 fpm +
Roll Great roll rate and feel. Ailerons have little inertia on stopping. Great roll rate and feel. Ailerons have little inertia on stopping. 10% faster roll rate.
Turning Pitch is good inside and out. Pitch is good inside and out.
Snap Good inside snap level and in the vertical. Outside feels good since the servo adjustment. Crisp recovery. Good inside snap level and in the vertical. A softer stall-edge inverted; but once rotating zooms around.Since the inverted entry required coarse inputs, recovery needs healthy inputs.
Acrobatic Flight vis. Very good Very good. Pilot needs to sit a little further to use the straight trailing edge as a sight.
Spin Normal for both. I forgot to do some. I watched several others spin upright and inverted and it all looked fine to me.
General Has very natural feel to my style of flying aerobatics. Pilot ss seated low, near roll center. I felt like I was on a perch. This particular seat arrangement was poor for me. It is too high; too far away from the center of roll. I felt on the outside of the roll action, being flung around. Again, the G-200 seat design is optional.

Kits cost the same. However, the MT prop on the G-200 costs $5000 more than the fixed pitch.

This comparison won’t cause anybody to choose one over the other; they’re almost the same. What’s interesting is the fact that a number of people are backtracking on monoplane size and horsepower. Those bigger monoplanes cost $100,000 to build as homebuilts. These smaller ones can be done for less than half of that. To buy an Extra, you’ll fork out a cool quarter million.

There’s no reason in the world why someone can’t produce an excellent performer using nothing but advanced composites. I often wondered why Burt Rutan didn’t do it years ago. Much of the Sukhoi and Extra airplanes are composite. But a weight saving? I’m not convinced.

I chose the One Design for two reasons. First of all, I endorse the concept of the One Design category, hoping for anonymity, one-airplane design, and a more technical category, rather than high G. Second, I’ve been flying Unlimited for ten years, and in that time, I’ve seen lots of unbreakable airplanes break. I’m realist; the airplane is going to break. I want to be able to detect damage before it gets too far, and I want to be able to fix it according to proven and documented techniques of repair. I can do all that with steel, wood, fabric and aluminum, and I have the books. With advanced composites, how do you know when it’s coming apart, how do you fix it, and how do you know when its integrity is restored to 100%?

ONE DESIGN ERRORS AND CORRECTIONS TO PART 1 AND PART 2


Drawing # and Drawing Title Comments
-001 Paint Scheme Indicate that the underside of the horizontal and elevator is painted red. Note One Design rules do not allow strips on underside of wing. Underside must be all red.
-117 Roll Over Safety Bar Use ¾” dia. .049 wall tube
-119 Formers etc. Part –7 should be made from bent up 4130 sheet, bent to 90 then bent at each stringer standoff. There is no part number for the belly former at station 52.00. It is made the same way as above. In Part 3 there will be more details of these parts as well as details of a horizontal former attached to –7 and diagonal tube –97 and –98 on Dwg –111 for attaching the wing root fairing.
-125 Fin and Rudder Full size rib flat patterns are incorrect, dimensions are correct
-159 SHT 1 Long Control Syst Add aileron stops. Details to be in Part 3
-150 SHT 2 Long Control Syst -63 typically is made with a bent flange on one side, then mated and welded along the edge during assembly.
-91 and –93 clevis plate are not usually assembled this way. –93 plate should be tapered and welded to the side of the –01 tube. This will be clarified in Part 3.
-151 Dir Control Syst Rudder cable should be 1/8 inch 7x19, not 3/32, Fairleads should be on the inside of truss aft of the cockpit. A bushing should be added at the forward end of the tailwheel attach to keep the attach tube from crushing when the attach bolt is torqued. Check to insure that the brake mount doesn’t interfere with the brake when pedal is fully deflected.
-201 Engine Mount All dimensions are intended for reference only. Engine mount should be mated with engine during assembly to insure fit.
-301/-901 Basic Wing Structure Install a clear plastic access cover for bellcrank inspection. Do not use this pitot system. Part 3 will include a better pitot/static system. Part 3 will also include a tie down attach using the bellcrank mount bolts
-304/-904 Wing Ribs 12.5 etc Move rib 12.25 to 12.5, the cap strip at BL 12 is hitting the truss and it will make the skin work out better
-305/-905 Wing Ribs 36, 48 Insure aileron pushrods do not rub or interfere with ribs. Be sure lightening holes line up prior to covering wing.
-309 Aileron Hinge mounts Bellcrank Assy drawing is drawn with the arms reversed in position. Check other views to insure proper assy. Bellcrank Bracket –29 flat pattern can make bracket too small if not bent up properly, check dimensions and make bracket match the bellcrank. Add tie down assembly forward face of spar. Details will be in Part 3. Bellcrank arms are made from 5/8” 4130 steel square tube .065 wall or from .050 thick flat stock folded as shown. Part –23 is 1x.049x3.125, -25 is 7/8x.058x2.45, ass a space between the bearings 5/16x.058x2.4
-310 Aileron Assy -25 is too small it should match the height of the real face of the aileron spar. Add corner blocks to the nose and diagonal ribs. Add stiffener plates to –33 aileron horn on fore and aft side. It will need to be stronger torsionally when the spade is installed. Spade details will be included in Part 3.

FUTURE ISSUES

Next issue we shall have a complete summary of the rules for the One Design Category. Along with a discussion of the rules and the concept. An article on ground handling of aircraft and more wing articles. We shall also begin describing fuselage construction. Please keep information coming.