BD-4 News letter # 28 ~ March, 2000

With the loss of Roger Mellema last August Several BD-4 Builders are attempting to continue the publication of his BD-4 news letter. While we will never be able to replace his talent, or even do as fine a job as Roger did, we are attempting to collect and pass on information about the Bd-4 for others to use.

This news letter will be available free if down load it off the web. If you wish to have a hard copy mailed to you, we ask that you mail $5.00 to cover postage, printing and handling.


Roger Mellema Memorial Jim Huber

The local EAA chapters (441 and 26) formed a memorial committee and came up with a plan. They decided on a memorial wall plaque at Oshkosh

($400) along with a perpetual trophy to be awarded at Oshkosh. This perpetual trophy is supported by an endowment managed by EAA. We are still researching who gets to call the shots on deciding on the judging rules and how to make fine adjustments to the process as time goes on. The current feeling is, that Rog would have preferred an innovativeness, etc. type award.

The endowment is for $1,000 for the award and another $1,000 for a trophy/plaque to be given to the winner. The endowment has been underwritten to ensure success, but we are asking anyone from the two chapters and the BD community to support this effort. An account has been set up at a local bank.

Roger D. Mellema Memorial Fund
C/O Washington Mutual Bank
1195 NW Gilman Blvd
Issaquah WA 98027


Empty Weights Steve Mahoney

It's always amazing to me how many aircraft show up at fly- Ins that are grossly over weight. While some of these fat aircraft may look beautiful and win awards for their craftsmanship, many of these cannot carry the payloads specified on their data sheet and still stay within their design limits. Aircraft flown under these overweight conditions will certainly suffer a sever performance hit, in addition to being operated with less margin to exceeding their structural limits.

I was at a fly-in a couple of years ago and this fellow had a won best "custom built" aircraft. The thing was truly a wonderful sight, beautifully finished inside and out. It had many coats of paint perfectly applied and clear coated. A leather interior with sound proofing, a complete radio stack and gyro panel with an H.S.I. It looked as if anyone would love to own and fly this aircraft until you looked at the data plate and saw the empty weight. It was 250 lbs. over what the designer had intended. Although this aircraft was designed as a two place aircraft, this particular example, could not even carry just the pilot, fill the fuel tanks and stay within the designed gross weight

I have discovered over the years that homebuilt aircraft are just like people the older they get the heavier they become.

Jim Bede Really did an excellent job of designing the BD-4 to be a light yet structurally strong design. It's when we exceed these numbers that we start to see performance degradation and problems with landing gear and the like.

I believe that a good empty weight for the BD-4 with an 0-360 to be under 1200lbs This includes all the fairings, modified windshield , fixed pitch metal prop.

Here are some of the things I did to reduce my empty weight.

  1. Install a flyweight starter. These starters weigh about 8lbs less than the standard prestolite starter that Lycoming uses and are far superior. They don't have that nuisance bendix gear that locks out once that motor is engaged, are more reliable and provide better cranking speed. One of these will set you back about $355. But you can recover most of this by selling your old starter to some poor guy who owns a Cessna and is forced to use certified parts to maintain his airworthiness. (One of the few times you'll thank the FAA) I bought mine from Chief Aircraft 1-800-447-3408 (no sales tax, its in Oregon)
  2. Get rid of that old heavy Lead acid battery. The latest technology is Dry Cell! I heard about this from a Vans RV flyer. They have been using the Odyssey PC 545 with good results for some time. This battery weighs only 11.8 lbs. as compared to 21 lbs. for a 25AH Concorde Certified Aircraft battery. It delivers 230 cold cranking amps, 225 for the Concorde. As these batteries are dry cells they can be mounted in any position (except upside down) and are very good in a high vibration environment. Because they don't vent they don't require a battery box ( there's some more weight you can get rid of ) The PC545 lists for $185 in the Chief Aircraft Catalog. I was debating whether I wanted to spend this much when I discovered that these are cells used in motor cycles and Jet Skies. I found a slightly larger cell ( PC 625) that was on sale for $79.95 at a Jet Ski shop in California (Aqua Sports (310)782-2815 or . I ordered it and had it shipped UPS to me and I have been extremely pleased with the performance. With this new cell and the flyweight starter it turns the prop so fast that I can practically Taxi without starting the engine. The PC-625 weighs 13.23 lbs. It delivers 265cold cranking amps and measures 6.7" X 3.9" 6.89" Odyssey also has a 24 month fee replacement warranty. These cells also have a much lower internal leakage than conventional wet cells so they don’t tend to loose charge if not toped off, as regular batteries do. I feel that these batteries really offer a nice easy performance upgrade over the old technology. Again if you can find one of those Cessna or Piper owner who are stuck having to use "Certified parts", sell them your old battery and you can move into the new technology for very little out of pocket expense.
  3. Interior, I recently changed my carpet. I found a much lighter weave at Home Depot. I was able to save 3 lbs. over the old weave
  4. My cowling is made of a very light weight Kevlar / glass layup it weighs 10 lbs. less than my old conventional fiber glass one did.
  5. Paint, this can really add up fast. my airplane only has on coat of paint on it. It may not look perfect but it's light!
  6. I used light weight- honey comb aluminum in place of the plywood for the floor boards shown in the plans.
  7. I machined off excess weight everywhere I could or added lighting holes to non-structural or critical parts i.e. The machined the metal oil filler neck, lighting holes in the rear seat tubes, door handles, tail spring, single leaf was tapered (before hardening ). My solid links that replace the rubber donuts in my landing gear box are made from magnesium. The center of the wheel axles where bored. This was a lot of work, for not a lot of gain. The BD airframe is really hard to beat, the way it is in the plans. I'm sure I could have lost way more weight for the same effort by going on a diet.

Summary: weight savings on N579SC

Flyweight starter 8 lbs.
Odyssey battery 8 lbs.
Kevlar Cowl 10 lbs.
New Carpet 2 lbs.
Floor boards 2 lbs.
mls. machining
Swiss cheesing 5 lbs.
Total Savings 35 lbs.

How much can you carry in a BD-4

This was a photo that was taken at the Arlington Fly-In. We camp under the wing. Yes, we squeeze every thing you see into the Airplane and fly 300 miles from our home in Oregon. Here is a sample of a few of the things we brought…. 2 adults, 2 children, 1 dog , 4 sleeping Bags and foam pads, Dome Tent, 4 bags of clothes, 2 lawn chairs , 2 Ice chests. We are still under Gross. with enough fuel to get to Arlington. The problem is more the volume of things rather than the weight. We have an extra large area behind the rear seats.


Experiments with Oxygen Concentrators Steve Mahoney

A friend of mine introduced me to these devices. They are often used by medical patients at home to supply oxygen in place of bottled O2. These devices are really cool . They plug into a 110 volt outlet

A hose goes to the patient to supply the concentrated O2. They vent the Nitrogen out the back.

They work by compressing air to approximately 20psi in a cylinder containing a ceramic bed of something? the nitrogen is then absorbed the O2 is then bled off. The devices contain two of these absorbing cylinders of which alternately cycled , charged with air and then bled off O2 and then purged of nitrogen.

My friend and I surmised that this technology would be perfect for supplying O2 on board light aircraft.

Compressed air from an electricity driven pump or bled air in……. O2 out!!!. It's almost that simple. As long as you have power, you have an endless supply of O2. We couldn't figure out why we haven't seen this technology on general aviation aircraft. I later found out that’s exactly how the military dose it on the Hairier Jump jet. My friend found a used concentrator on Ebay and bought it. It was much larger that I thought, but I believe that by removing the case and all the sound proofing and replacing the 110 volt compressor the size and weight could be reduced significantly.

Just to see if we if the whole idea would work I volunteered to flight test it in my BD-4. I loaded the concentrator in the back seat along with a computer UPS to provide the 110 volts power source. I also took bottled O2 and a Spo2 meter. The Spo2 meter is an instrument that measures the O2 level in your blood with light. You simply slide on a small finger cuff and the instrument reads out pulse rate and O2 saturation on a digital display. At 10,000 feet it's normal for my spo2 level to be 85% with no supplemental O2 ( I work for a medical electronics company so I have access to this equipment)

I took the connector to 18,000 feet. It supplied over 5 liters a minute (more than enough for 2 people) of O2 with no apparent problem. I was able to achieve a 95% saturation of my blood equal to that of what I was able to do with the bottled O2.

So it seems to work ok, now we need to figure how to simplify it, shed the extra weight and get the size down. I see the day when we will have a switch on the instrument panel that turns on an endless supply of O2 with no expensive bottles to refill.


Onboard Oxygen Generation Systems (OBOGS).

The idea of producing oxygen in flight is very attractive since it minimizes logistic support for oxygen and increases operational safety. Several OBOGS systems are currently being evaluated. These systems include electrochemical concentration, fluomine chemical absorption, permeable membrane, and molecular sieve.

Currently the Navy's AV-8B Harrier aircraft utilizes the molecular sieve OBOGS. In the molecular sieve system (Figure 1-24) bleed air from the turbine engine is alternately pumped between two molecular sieve beds containing aluminosilicate crystals called zeolite. The oxygen is separated from the nitrogen and concentrated. The oxygen-enriched air is then available for use through the normal oxygen delivery system. During the separation process using the two-bed systems, as the first bed is concentrating oxygen, the second bed is removing nitrogen and releasing it to the atmosphere. The cycles are then reversed with pressurization of the second bed and exhaustion of the first bed, thus producing a continuous supply of oxygen. System startup is virtually instantaneous. The enriched air supply proceeds directly as the bleed air supply pressurizes the system. When the aircraft is ready OBOGS is ready. The onboard oxygen generating system is a revolutionary oxygen system which yields a continuous supply of breathing oxygen to the air crew member with no replenishment requirements. If there is any drawback to the system, it might be the fact that at best this system can only provide 95 percent oxygen, with 5 percent argon.


Web sites of interest Matronics List Archive Search engine. This is useful way to search for information on homebuilts . The BD-4 is not specially mentioned however I find it useful way to general information such as engine exhausts for example. This is a very popular site devoted to aviation in general This is a great BD-4 site by Mark Napier Reference the BD-4 archives notes Tennessee Valley Aviation BD-4 kits and parts


Dream Aircraft Panel ribs soon Available

Ed note: I am vary excited about the work that Scott DeGaynor is doing to provide a high quality ribs for builders. He and John Gill have made a major investment in tooling, research and development. They have produced 7 panels so far, but want to continue to perfect the process before they release it to production.

Last minute update: 4-13-00 Scott sent me a short note to say that he has partially assembled one wing and it came out perfectly straight. (I sure look forward to this) It should also be noted that his wing has flapper valve that prevent the fuel from sloshing to the outer bay tanks.

Dream Aircraft aluminum panel ribs are progressing nicely. While they hesitate to say much until at least one wing has been completely assembled, there are hopes this will happen by Mid March,2000. Ribs are made in permanent metal dies and made to the original airfoil specs with the BD mod. The rib has the spar flange formed into the rib making it one piece.

The process is first to waterjet cut the rib, wash it to remove any

abrasives, Lube it, and put it into the first die. One stamp of a large press and we have the center flange. The blank is placed into the second die and in one cycle we have the flange around the edge of the rib. We are using .032--2024 T0. The forming of the stiffeners make it rigid and we've discovered the heat treating process warps it and gives it very little strength advantage.

These ribs are useable, as is, for anyone wanting to build a wing by

fitting ribs then riveting skins. There are enough ribs in stock for about 10 wings. I will have pricing set soon.

The panel ribs are four pieces glued together in permanent fixtures. The adhesive is used by the military and is the latest . It is even better than pro-seal. Each panel I glue raises the price because of the rubber glove count per panel. The gluing strip leaves 3/4 inch for the over-lap glue joint.

Panel ribs will be priced after we have produced enough to assure quality and have realistic production times.

Contact: Scott DeGaynor at Dream Aircraft 616-776-0840


Low Cost Oil Cooler Steve Mahoney

This is a simple, Low cost, yet effective oil cooler I made for my BD. I used to have too high of oil temperatures when climbing out with a full load on a Hot day. I didn’t want to take any more bleed air off the Baffles, so I Just put the pipe in the exit of the cowl. It is so simple there is little that can fail or leak. I was surprised at how well it worked. I did, however have to adjust my oil pressure regulator to compensate for the added pressure drop by the added length of tubing.



Avemco Header Tank Policy on BD-4 recently changed Steve Mahoney

Over the past several Years, I have had several conversations with Avemco in regards to their policy requiring header tanks for insurability of the BD-4. I believe that this policy encourages a high degree of experimentation with the fuel system of unproven designs. With the encouragement of Roger Mellema I have proposed to Avemco that they modify the requirement in favor of placarding the Gauges with “No takeoff with less than ¼ tank”. Recently, I was contacted by Jim Lauerman of Avemco. After considering technical input from Bob Hoey, They have agreed to change

Their policy. As of April 1, 2000 a header tank is not longer required to recieve insurance from Avemco.

Many thanks to all who helped change this policy and make it a safer situation.

Tennessee Valley Aviation Steve Mahoney …a conversation with Charlie Musitano

Fuselage Kits

I talked with Charlie Musitano of TVA today (March 22, 2000). He has an inventory of 20 fuselages ready to go. All the parts are first class, made of quality materials, Anodized and shrink wrapped ready for shipment. Those of you who attended Oshkosh last year got to see for yourself the high quality of these parts.

Windshield Corners

TVA has recently received a shipment of a new angle that is used for the corner of the windshield. These are formed with a larger .800 R. improving the aerodynamics by reducing the turbulence caused as the air flows around the sharp corners of windshield posts. Charlie says that he is very pleased with the quality and the way these new parts came out.

Landing Gear Legs

Scotch Ply for a new landing gear leaf has arrived. They have enough to build 8 sets. Ed Note: “This is something I’ve always wanted to do to my BD. I think that there could be a very nice weight savings and the Scotch Ply gear, if deigned correctly, should be more flexible, thus absorbing more energy and imparting less to the fuselage in a hard landing. I believe that scotch ply is the same material which Jim Bede designed into the Grumman Yankee. It is also used in the, cheetah, tiger and traveler series aircraft so it has been well proven over the years.” Charlie says that the traditional aluminum gear legs will also be available as well.

New Nose Gear

A new fork casting which allows a wheel size 500X5 has been designed and manufactured from AL-Mag

This larger wheel size should be a welcome improvement over the old Scott tail wheel.

Engines and Props

TVA has recently made a deal with Lycoming to provide engines for the kits. They have obtained special pricing on the IO360 A1A 200 hp. Charlie says these deals are so good that you should contact him for details.

They also have a special deal worked out for the smooth running 6 cylinder 220 hp Franklin as well.

Props -TVA also has agreements with Hartzel and Sensenich as well, and can make you a good deal.


How to contact TVA

Tennessee Valley Aviation Products, Ltd. (256)704-2728 Fax (256)704-8827
2225 Drake Ave. Suite 17
Huntsville, AL 35805
Web Site




A recent rash of newly completed airplanes in our area (mostly RV-4's and 6's) prompted me to try to get a little more speed out of my BD-4. ( Besides, my old carb. heat box was getting pretty dilapidated after 20 years of flying.) My cowling was the original BD design with the air taken from the left rear baffle, ducted down to the carb. heat box, and eventually into the carburetor. The air had to make six 90-degree corners before entering the carburetor. I have always admired the simplicity of the air scoop and carburetor air box on Van's designs, so I decided to try adapting it to my airplane. I purchased both the air scoop and the air box for an O-360 from Van's aircraft. The air box was installed on the carburetor essentially per Van's instructions (fig. 1 & 2). Portions of the flange on the air scoop had to be trimmed off and reformed to match the lower contours of my cowling (fig. 3 & 4). I also extended the rear portion of the flange outboard to cover the exit area at the rear of my old cowling. The new glass was laid up right on the cowling after taping Saran Wrap to protect the paint. The completed installation is shown in fig. 5 & 6.

Temperatures were a little high on the first flight so I altered the rear end of the scoop. It was flared downward slightly to help pull the cooling air from the engine compartment (fig. 3 & 4 are the final config.). My exhaust system has a heat muff directly above the air box which tends to minimize the amount of hot air entering the air box when the carb. heat valve is open, so I redirected the 2 inch scat tube duct from the heat muff into the area above the new air box.

The result? I picked up about 100 RPM in level flight at full throttle, and about 200 fpm climb rate. (fixed pitch prop, 74D-65P). The engine is obviously "breathing" better than it was with the original air induction system. The modification turned my old cruise prop into a climb prop, so now I need more pitch.

I recently borrowed one of Sensenich's new fixed-pitch metal props (71D-83P) and flew a trial flight. My maximum speed was 190 mph true, with an honest cruise of 180 mph at 2600 rpm (5500 ft. altitude). Not bad for fixed pitch!!

Bob Hoey