Dear BD-4 friends,
Here we are back with you again. A little later than I wanted but with a double sized newsletter and lots of interesting letters and facts! I have been inundated with letters from interested builders who have been inspired by the article on John Brecher's BD-4 that was in Kit Planes magazine! Many people have requested past issues of the newsletters and most of those have been sent out now but I still have a lot more copying to do. Of course, the largest problem with trying to build a BD from scratch is the availability of spars. Bede has indicated the possibility of making a spar buy - see below. One other possibility is to make a built-up box spar for the BD. Some people are now working on that.
NEWSLETTER DUES
The newsletter dues are $5 for 4 to 5 issues each of which is usually 9 pages of text and figures (when they get late, they usually get twice that big). If you have a "@ "symbol before your name on the address label, you are good for about another 2 letters. If you have a "+" symbol you are good for more. If you have nothing, a "-", or a "* "you are being dropped from the active list.
HAPPY 20th BD-4 ANNIVERSARY
It has been 20 years since the first BD-4 appeared at Rockford and this year at Oshkosh we had the biggest gathering of BD-4's yet. The official count as of Tuesday morning was about 37. This is kind of hard to keep track of as some people come early and leave early or don't park in the "show" area. They fell into the following categories: fancy, good transportation, heavy, beautiful, fast, light, quiet, comfortable, old, new, expensive, two, three, and four place, trigear, conventional gear, spartan, noisy, and slightly damaged! As to which planes were which - you had better come and judge for yourself next year. I don't think I have seen any wider variety within one type of airplane except maybe the Pietenpol. I can't wait until we see the Ford 351, Mazda rotary, Oldsmobile V8, and the Ford V6 engined versions next year!
A small judging effort was undertaken and the best BD's for this year were as follows.
Deere Ogden was judged third. His BD is very clean and neatly detailed. I like the bright effect the green and whte paint job give it. It has a complete interior which is where most BD's are lacking. I like this airplane as it is nicely done but not overdone. I think it would score higher if total utility were taken into account by the judges (useful load etc.).
Don Phillips was judged second. Don has won several awards for his BD, one of which was a major Oshkosh award. Don's BD has very nice lines and a very professional looking paint job. There are some BD-4's that you Immediately notice are nose draggers, but on others like Don's, the paint scheme seems to hide the fact that there is a training wheel on front (spoken like a true tail-dragger pilot!). His BD has been flying for several years and still looks like it was just finished. He is turbocharged and likes the altitude performance.
The grand prize winner was Steve Takes. I must say that I have never seen a more beautiful BD-4. I don't believe that there was any doubt in anyones mind as to who would win the award for the Best BD-4. When Steve taxied in I immediately liked the paint scheme. The basic design is of burgundy stripes down the side of the fuselage. No clutter, just nice and simple. The interior is actually fancier than the outside. Almost the entire interior is of leather of a color that complements the burgundy stripes. The front seats have much taller backs than normal and look to be very comfortable (I don't like to ask to sit in someone's fancy airplane for fear of scuffing something). The instrument panel is nicely done with a very full line of avionics. The most noticeable item on the airplane are the moldings around the inside of the windows. They are made of balsa wood glued together to ft around the window and then sanded and filled to a very smooth surface. They were then painted to resemble the real wood moldings on Bentleys and Rolls Royces. Anyone who has tried to make the windows in a BD look nice knows how much work must have gone into this. All in all, a very beautiful airplane and just in time for a few years of retirement travelling.
Steve's wife, Lou, had only been in the BD for a very short ride before they started out for Oshkosh. She has been a little wary of flying homebuilts after hearing all the little problems and horror stories at our BD-4 discussions at Oshkosh. She did great on the trip and spent a lot of time at Oshkosh keeping their BD safe from predators. Maybe we should have one meeting where all we do is talk and show pictures about the family trips we have taken and/or we could talk about performance issues.
In addition to the awards reported above, I feel that there were some other airplanes that really stood out this year.
The first of these is Ray Ward's Super BD-4. Ray should really give everyone a ride so they can feel the performance of this airplane. There would probably be a few more of them made (you could buy Rays but I don't dare tell you the price here). Ray knows what a good BD is worth - it's too bad the rest of the world doesn't. Ray of course has also really promoted the BD-4 by winning the CAFE 400's Tri-Aviathon this year. Congratulations Ray!!!! Ray is now interested in something to do during the winter and is looking into some super Fowler flaps or other methods of improving his CAFE score.
Dick Marker had his turbocharged BD at Oshkosh this year and took off his cowling to make us drool. I always envy a neat engine installation (you've never seen under my cowling have you?). Dick has more things under the cowl than I thought you could put there. He lives in Idaho and really needs the high attitude performance provided by his turbo installation. The rest of Dick's BD is also very pretty. He used some non-traditional aircraft colors and made a really beautiful airplane.
John Bracher had his new BD there this year with a whole load of people. John also used non-traditional colors to a real advantage. Check out the September issue of Kit Plane magazine for good photos and story. I really liked the interior of John's BD-4. It was really well done.
Lloyd Brekke finally got his BD to Oshkosh at the same time I was there. It is hard to believe that his BD has been flying all these years and still is so beautiful. For those of you who are newcomers to the BD-4, Lloyd and his wife Janice worked for Jim Bede during the glory years. Most of us traded phone calls and letters with Janice as she did her best to get us the parts that were due us.
Lloyd demonstrated his new Loran to me during one of the airshows. I have used my SRT Labs model now for several years and while it works as good as any, I sure like the new features that Lloyd's has. The Fybrary is really helpful especially the emergency modes where it will lead you to the nearest airport.
Steve Mahoney and family had their BD-4 at Oshkosh for the first time this year. Steve's BD is exceptional in that it is the only BD I know of that competes with Bob Hoey's for simplicity and light weight We all know that a light airplane is the best airplane but it seem against human nature to leave things simple. Now we all know that engineers are not human (I can say that - I know) and so they take great pride in making very efficient flying machines. I think Steve's real reason for all the extra effort is to be able to beat me in a CAFE type race and with a fixed pitch prop yet! Steve even does things like milling down the Scott tail wheel as it is over-strength by a bit. He has also influenced me to build lighter. I did a lot of weight reduction as I re-built my BD. A good empty weight goal for an all-around most useable BD-4 with an O-360 and constant speed prop would be below 1200 lbs.
Bob Hoey has been an advocate of properly light airplanes for a long time. This is probably a carry-over from his work in the flight test area. Bob has no desire to fly in bad weather and so does not tempt himself by loading the panel with equipment that is really only used for IMC flying. I have to admit that I plead guilty in that I have carried around a lot of equipment that gets used very little. It is a shame that people at fly-ins ignore the beautifully engineered and built airplanes and seem to "ooh" and "ah" over the lead sleds with the super plush interiors and 1/4 inch thick paint jobs.
I think we should come up with a special Oshkosh award for the most "intelligently built" BD4.
Scott DeGaynor had his airplane back this year and said he and Jon worked on landing gear fairings until just before Oshkosh. Scott's cowling is the most admired of the BD-4's. The prop extends out a long way and the cowling is very pointed and sleek. He also has improved the restraint systems in the cabin to make it safer in the event of an accident. Scott has a specially builtup engine that is super smooth and puts out a lot of extra horsepower.PHOENIX?
rdm
My BD-4 is flying again! We still haven't moved into the new house but we decided to get the BD back on the gear again and so made Oshkosh '89. We homebuilders are always optimistic and so I gave myself 3 whole months to get it rebuilt. I expected that it wouldn't get painted and I wouldn't stretch the fuselage as I had off and on planned. All I had to do was replace the main landing gear box, both side channels, the floor, the firewall, the front lower angle, the left windshield angle, the cowling, put in a new windshield, all new side windows, repair and skin the doors, replace all lef side skin and 1/2 of the right side skin, replace lower Left engine mount, fix steel engine mount, repair the instrument panel, straighten left box brace (from spar to left lower engine mount), insulate the firewall, re-install engine, sand blast and epoxy chromate all 4130 steel parts, rewire the instrument panel, rework the baggage compartment, put everything together, flush all fuel systems and fly for confidence (I also did 0 SMOH on the engine).
After 2.5 months of rebuilding I flew it and found out just how many people were betting 1 couldn't get it done in time! So what if I still had a few clicoes sticking out here and there. What fund is to have a flying BD-4 again! I should have rebuilt it sooner.
After 5.5 hours of high power test flight I put the old banged up fairings on again and left for Oshkosh. We made it in 9 hours and 10 minutes. At 10,000 foot, 20 inches MP, and 2100 rpm, the corrected cruise speed is 193 mph.
I did some new things while I rebuilt my BD:
I lowered the center tunnel a lot so 1 could lower the front seat more and so the back sling seats are more comfortable. The 4130 steel elevator push-pull tube had to be bent downward but this doesn't hurt as long as it is bushed with micarta so it can't straighten when it has large loads put on it, I put a rub bar of micarta above the elevator bar right at the back of the main cabin and inside the top of the tunnel. The tunnel goes from main landing gear box height down to 1.75 inches at the rear of the main cabin and is 3 inches high at the rear of the back seat compartment.
The brakes on a BD-4 always seem a little weak so I have always had the tops of the master cylinders hooked up closer to the pedal than the plans call for. This with the 'race-around' belcrank system (see issues 1 through 3) have proven out to be an adequate solution. Upon rebuilding and trying to lighten the load, I decided that there must be a better way to get braking effectiveness. I took out the 'race-around' mechanism and substituted a pulley mounted to the front of the main landing gear box. A piece of old cable around this connects to the rudder actuation levers at the center of the cockpit. Now it you push on both rudders (to get brakes) the rudder cables won't be streached as you are pulling against the landing gearbox. Be sure to put a couple of angle stiffners in the landing gearbox or it will flex a Iittle when you really reef on the brakes. The old system put the force against the firewall. The new firewall can't take much force as I got rid of all the angles that were really just for the nosegear. To get better mechanical advantage from the rudder pedals to the master cylinders, I inverted the brake lever arm on the forward side of the top portion of the pedals. I then reshaped the forward portion of the lever arm and made it about one inch shorter (this was the same hole I was previously using). To do all of this I did have to remake the bottom mounts for the master cylinders. I moved the master cylinders down about 3/4 inch. The new brakes work much better and my whole assembly is lighter.
At Oshkosh someone said that Gerdes also makes a master cylinder with a smaller diameter piston. it is called a 0.049 -10P Gerdes master cylinder. This will also give a better mechanical advantage against the wheel cylinder.
I made a new baggage compartment. I initially used a canvas bag that was hung from the side fuselage angles. I didn't like the way this looked or worked. To improve it, I first buitt a tunnel (.016 AL) over the cables and riveted it to the floor to strengthen it for the heavier loads and then used sticky back foam on all surfaces for insulation and protection.
I have always had high friction in the aileron system so I decided to fix it while everything was open. I first cleaned and lubricated the torque tube bearings. They can be opened on one side by removing the plastic seal. I cleaned them and lubed them with WD-40 only. I have had trouble with other oils and greases turning sticky. Next 1 took out all the cables and pulleys and replaced them with push-pull tubes and belcranks. I used .035 wall, 1/2 inch outside dimension 4130 steel tube just like in the rear door frame. The belcrank is made from 1/16 inch steel and a belcrank bearing (6 to 7 dollars). The 'arms' on the belcrank are only about 1.5 inches long. I used all rod end bearings to keep wear down. I still have to put bearings in the rear belcranks as in the Bede design, the belcrank support brackets wear very quickly and cause slop in the ailerons. Try moving your stick from side to side and watch the belcrank cock sideways! I really like the new arrangement. it also makes it easier to set the ailerons.
A change I should make but haven't yet is the lack of fuel finger strainers in my wing tanks. I have very good fuel cells and don't want to cut into them so I will have to find a different way. Right now I very carefully strain everything that goes into the tank. Steve Mahoney came up with the following solution. Make a strainer out of very fine brass mesh or other material that will not let water through and make it so it lowers into the wing tank. The strainer can be pulled up to see if you were sold any water or other garbage. The strainer can be stored in one of the tanks.
SHE DANCED ONLY ONE SUMMER
by
Jost Walliman
Zurichstr. 5
8124 Maur, Switzerland
Dear BD Friends,
This will be my last contribution towards BD building and flying. It took eight years or more than 5000 hours to build my BD4. I had to do most of the parts like cowlings, ribs for the elevator etc. myself as the BD company went bankrupt after I had paid for all the parts. Now my BD-4 is no more.
I had all the fun and pleasure of flying the airplane for one summer. it flew without any problems during all of 1987. Last November I towed it home to store it over the winter months and to do some work on it. On the first flight on May 26th, 1988 I had an engine failure after take-off. I took off from runway 28 on the International Airport of Zurich. After take-off I turned left 90 deg to the axis of the runway. Over the parking area of the airliners arid the big hangars, at a height of approximately 1000 feet the engine stopped. As I was over a built-up area I thought the only choice was to return to the take-off runway and land on the remaining end. Then things happened rather quickly. After a 180 degree turn, on short final approach, My BD snap-rolled on its back and we hit the runway up-side-down.
Four minutes before my takeoff, a DC-9 had departed on the same runway. I am now unable to remember whether I stalled or whether the snap roll was caused by wake turbulence.
The BD is a write-off. I was able to free myself with only a broken foot, an injured knee, and a few bruises and scratches. I was glad to have been on my own as the pilots seat was about the only place not crumpled up.
CONCLUSION- Being aware of the fuel problems on the BD design, our FAA inspector asked for a header tank on the firewall which I installed as you can see on the enclosed drawing.
- I had a mechanical and an electrical fuel pump installed as well as a free flow gravity feed by-pass system.
- A post-mortem inspection of the almost zero-time engine showed no defect on the engine itself. it has to be assumed that the source of the problem must have been fuel starvation.
- Before the first flight I made a fuel flow test (see enclosure). During the flow test the hose to the carburetor was disconnected and the airplane put in climb position. No problems stowed up. Probably because the hose was disconnected and an airlock could not build up. For the first engine test I assembled the airplane back home and filled the wing tanks with approximately 12 gallons each. I could not get the engine to run. Even though the fuel valve was In the 'both' position there was no fuel in the line behind the valve. After bleeding the system the engine started on the first kick. I thought I could overcome the problem by installing an electrical fuel pump at the firewall. After all the testing was completed, we towed the BD to the airport and assembled it there. That was on that cold and wet spring of 1987. With all the gadgets I had made up, the assembly of the wings took no more than haft an hour. Wtth everything ready (40 gallons of fuel in the wings) I cranked the engine - no start. This time I had fuel up to the gascolator but apparently not in the carburetor. We undid the fuel line from the primer pump to one of the cylinders to check if we were injecting any fuel. We found fuel there, connected the line, arid tried again. The engine started the first time and them ran without any problems during the whole of 1987.
I SHOULD HAVE TAKEN THE ABOVE INCIDENT MORE
SERIOUSLY!!!!!!!!!!
Spring 1988, after the same assembly procedure the engine started, this time without any problems. Again wtth 40 gallons of fuel on board I taxied to the run-up checked the mags and took off. As already told, the flight ended only 3 minutes later up-side-down. Apparently the engine ran until the header tank was empty. (The header tank was not drained during the non-flying season.)
I have now ordered a Glasair-kit
All the remains form my BD are for sale or to be given away free. There are: wheel pants with integral landing lights, all the various welded parts like the whole control system, the complete elevator, gear legs, wheels and brakes, tailwheel and spring, the newly developed quick mount and dismount mechanism for the wings etc. The spars are already sold.
FUEL FLOW CHARACTERISTICS
With all three wheels on the ground, there is no fuel flow by means of gravity feed below 12 gallons in each tank. With the help of the booster pump, fuel flow starts above 6 gallons in each tank. The angle with all three wheels on the ground is equivalent to a 10 deg climb.| FUEL FEED | FLYING ATTITUDE | 10 DEG CLIMB |
| Gravity only | 29 gph | 24 gph |
| Booster pump | 37 gph | 37 gph |
| UNUSABLE FUEL | 1 gal each | 6.6 gal each (booster on!) |
Jost Walliman
ed note:
We are really sorry to hear about your BD. As the pictures show, the airplane appears very well done and I believe the only one operational in Europe.
When Ray Ward flew the CAFE 400 two years ago he also had a problem with fuel flow. We had drained the tanks so that he would know exactly how much fuel was in the airplane for the Tri-Aviathon As we were doing it, he said that after refueling we should open the quick drain on the gascolator and blow on the fuel Cap openings to be sure there was no air in the lines. We forgot and on his takeoff the engine quit cold. He wisely closed the throttle and landed on the end of the, runway. Ray has his fuel lines along the back of the door just as Jost has and even this didn't prevent the problem. After Ray brought the airplane back to the ramp, we blew into the tanks and that solved the problem.
After I rebuilt my BD recently, I flushed my entire fuel system to make sure I wouldn't have the problem again. After cleaning everything, I decided to do a fuel flow check. I left the tail on the ground and put 12 gallons of gas in each wing. The fuel would not flow by Itself (gascolator drain open). I blew on the caps and immediately got the fuel to flow. The flow rate was about 20 gph through the small drain in the gascolator. The gas continued to flow until there was about t gallon left in each tank.
I had only one problem in that one of the tanks flowed for awhile and then quit when there was still 5 to 7 gallons left in the tank. ApparentlyI had not cleared the air out of both down tubes from that tank. I guess the only one that was flowing was the forward one. This would explain why it flowed for awhile and then quit when the fuel got below that outlet. After blowing on the tank again, the rest of the fuel flowed out.
If you have a header tank, it is really important that you be able to see how much fuel is in it. Jost probably did some ground running before he tried to take-off and he was just cutting his margin of safety given by the header tank as he was using fuel out of it and the tanks were not flowing into ft.
Fuel pumps don't always pump the air out of lines and suck the fuel through. However, sometimes they do. I can set a can of gas on the ground and as long as the engine will start, it will suck all the air out of the line and start the fuel flowing. This is with the plastic line connected to the wing root fuel fittings.
I have never had a problem in getting fuel to flow once it has been interrupted while in the air. I have done several tests where I slip the airplane so that the engine quits, then push opposite rudder and in three seconds or less, the engine starts again. I have never then had it quit again.
A major lesson to be learned I guess, is that the air should always be purged from the lines after they have been emptied. When removing wings for maintenance, don't drain your tanks through the gascolator, siphon it out of the tanks so that the down lines stay full.
BEDE-4 WING SEQUEL
by
Paul E. Kauffman
3625 Holliday Village
Traverse City, MI 49684
As always, first efforts to design something, e.g., a new wing for the BD-4, result in complicated solutions. Subsequent to my comments in the previous newsletter, I have simplified the design of the new wing considerably. The accompanying sketch shows some of the details. Replacing the complicated system of fuel filling, storage and management is a simple flush fuel cap which closely preserves the airfoil contour. Sketches of both the current wing design and the flush fuel cap are shown here in figures 1 and 2.
I make a trip to Bryan, Ohio to help Dick Schrader skin the wing of his HP22, and learned a good deal about how to accomplish this task. Using a router and an accurate template of the airfoil from leading edge to the face of the rear spar, accurate ribs are easily cut from sheets of 1/2 inch thick PVC foam sheets. Likewise, aileron and flap ribs are also cut with the router. At the ends of the wing and the ribs at the ends of the fuel tank, 6061-T4 by 0.050 inch is used to form these 4 ribs for each wing half. The rest of the ribs are cut from 1/2 inch PVC foam sheets. In addition, the foam ribs within the fuel tank area are faced with 0.012 inch thick 2024-T3 or 6061-T6. This helps increase the shear strength of the foam ribs in the fuel bay area thus helping support the fuel load. This 0.012 inch facing is adhered to the ribs using the 9410 or 9412 Dexter Hysol adhesive. Shear strength of the PVC foam is 90 + lbs per square inch without the 2024-T3 facing. While this is probably adequate for the fuel loads encountered, the 0.012 inch facing enhances this markedly. With 4 inch spacing of the ribs a full tank carries about 3 gallons or 18 lbs of fuel between each rib. The full capacity cannot be filled, but, minus the vented airspace, there will be somewhat less than 30.5 gallons in each tank
Unlike Dick Schrader's HP22 spar which is rectangular in cross section, our BD-4 spar is round. This poses a problem. How can we accurately line up the ribs when they are "glued" to the round spar? While I have yet to accomplish this task, I plan to use holes drilled in the chord line of the rib template to line up the ribs. These holes along the chord line - drilled through the template - are used to locate The holes in the foam, and using bolts, hold the foam as it is cut with the router. Bolting a straightedge to the end rib (using the chord line holes) this can be used to line up another straight edge bolted to each rib as you "glue" it in place. Obviously it is important that all the ribs be lined up carefully assuring no twist in the wing, i.e., the rear spar must be parallel to the main spar. This is necessary so the skin will fit.
The flange of the metal ribs is formed over a template backed by a somewhat smaller rib-shaped block folding the 6061-T4 metal firmly in place with bolts or clamps. After starting to form the flange area around the radius of the template, a flush riveting tool driven by compressed air is run along the flange to form the rib. Any bowing of the rib face is then removed using a metal shrinking pliers. Eight of these ribs are required (4 on each Wing haft). Metal ribs are also required to support the 2 aileron bearings and the 3 flap bearings.
After the ribs are adhered to the spar and the rear spar is adhered to the rear ends of the ribs, the leading edge radius is formed on the skin and the skin is fitted to the wing. After fitting the skin and drilling holes to cleco the skin to the rear spar and the metal ribs on the ends of the wing, it is time to prepare the skin for the epoxy adhesive and "skinning" the wing. More on this procedure later.
Bending both the leading edge radius in the wing skin and the channels for the roar spar is somewhat of an artistic experiment. Never-the-less, they are feasible tasks for the homebuilder. Dick Schreders article on bending aluminum channels from the latest issue of the Sailplane Homebuilders association newsletter is copied here. Likewise, the article on Bending Leading Edge Aluminum using Vacuum is found in Sport Aviation, April 1986, in the "Craftsman's Corner", page 61.
Paul K.
Click on image for larger view
Click on image for larger view
Paul says that Dick Schrader has 6 inch OD 6061-T6 tubing in 12 foot lengths. Wall thickness is 0.070 inch. This fits inside the fuselage center section and could be used to strengthen the spar. This is thinner than the cabin spar wall thickness so It is not as it you had a longer cabin spar.
PROPELLERS
rdm
There is a perfect twist for each rpm/air speed combination but each portion of the prop has a different airfoil so the maximum lift/drag occurs at a different angle of attack. The airfoil tends to be a Clark Y at the tip and more symmetrical airfoil near the hub. The cord of the airfoil does not change much but the thickness does change and so the camber.
On top of all this, each portion of the prop travels at a different speed and all motion is at 90 degress to the airstream which changes from 0 to 200 mph during flight operations.
Now you might ask - what set me off into this nightmarish world of multiple nested integrals where everything seems to be variable? Speed!
Dick Marker approached me at Oshkosh and asked if I knew that most constant speed props were twisted for 120 mph. He had re-twisted his propeller for higher speed and picked up about 10 mph in cruise. Yes, we do have constant speed propellers but that does not get rid of all the problems. An ideal propeller also has to have a variable twist along the blade. This is of course close to impossible. So our problem then is to do a tradeoff study to determine the best combination of takeoff performance and cruise performance. I really had not thought about this very much and had assumed that a constant speed propeller gave me the best of all worlds.
I went home and wrote a computer program to make it easy to generate the propeller station versus the pitch angle curves I needed. I also measured the twist on my prop and indeed found it to be twisted for 120 mph just as Dick said. I plotted the ideal twist for 200 mph and then moved the 120 mph curve over to the vicinity of the 200 mph perfect twist curve. This is what a constant speed prop will do to load the engine for a specific requested rpm. The difficulty with analyzing a constant speed prop is that I really do not know what the exact angle the prop goes to for each rpm/airspeed combination. The majority of thrust is produced near the tip of the prop so I chose the 75 % span point to set the two curves equal. This allows us to see what angle of attack the chord of each station of the blade will have in cruise. As you can see in figure 3, the tip will be 2.8 deg more than optimum angle of attack and at the 11 inch station the angle of attack will be -4.7 deg less than the optimum.
If the prop is twisted for 200 mph and is then used for climb at 80 mph (best angle), the prop again is not optimum. Figure4 shows the 200 mph twist curve shifted to the left to correspond with the 75 % of blade twist for 80 mph. The tip will be 4.6 degrees less than optimum and the angle at a station of 9 inches will be 11.4 deg mare than optimum. This indicates that you may have the inner pad of the blade stalled. As you can see from the curves, higher rpm is better for root of blade performance.
Overall, if you already have a lot of take-off performance, you certainly want to twist your blades for cruise. I was toll that it would cost about $130 to have my blades re-twisted (if I supplied the station/angle data - they had no idea taw to derive ft themselves).
I also checked our Piper Aztecs blade twist and found it to be 100 mph. This seemed strange at first but it turns out that it is optimized for the best single engine climb rate speed. They apparently are more worded about single engine performance than cruise speed (as they should be).
Ray Ward's Super BD-4 uses an SX-300 prop and so I expected the twist to be too much for his slower cruise speeds. Ray checked out the twist and It corresponds to about 230 mph. His economy cruise is about 220 mph so his prop is not hurting him much at cruise but certainly is hurting him some in climb at slower airspeeds. However When you have so much excess power your best angle of climb is nothing to worry about and the best rate of climb speeds (120 mph) will rat be hurt too much.
The formulas needed to analyze your prop are as follows:
ANGLE NEEDED =ATAN { (Vel *1056)/(rpm * 2
* PI * Station)}
Velocity is in mph, station is in inches
from center of prop.
Click on image for larger view
WINDSHIELDS
rdm
At Oshkosh and after I've had a lot of requests for the curved windshield. I called my supplier and the new price is $230 plus $50 for the crate. The windshields can be obtained in clear or photo grey colors. The thickness we are using is 3/16 inch. I flew the prototype windshield for 5 years and it was only 1/8 inch thick. We probably could get you a 1/4 inch window if you so desire. The shipping varies from 60 to 90 dollars. I will need pre-payment of the full amount (excluding shipping) by December 15, and the windshields will be sent within about 6 weeks. If a lot of orders come in earlier we will probably get them sent a lot sooner. These windshields extend forward over the engine area by 10 to 12 inches. This means that the firewall is also extended forward from the top of the present firewall. It you have an original BD engine mount, the window will extend just past the top bar and will be just above ft.
Usually, the cowling can be cut and refit with no problems.
It is somewhat harder to work on the top rear of the engine but I think the extra speed is worth the effort (I get about 10 mph). You must take care so that the transition from window to side of the fuselage has no abrupt "breaks" in the curvature.
TAIL WHEEL SPRINGS
rdm
As I was rebuilding my BD, one of the tasks was to reinforce the tail wheel spring attach area. As you know, the BD method for Installing the tail wheel was not strong enough. First of all the tailwheel spring supplied was a three leaf arrangement that is much too stiff. We have now gone to one leaf which works fine and also reduces the stress on the rear of the fuselage. The BD supplied spring also was short enough that the "front" of it ended right in an area of the fuselage that has absolutely no strength. The BD method of adding an angle did not work at all so there were several solutions by the builders. These solutions were covered in an early newsletter.
While trying to decide which solution to use, Steve Mahoney suggested that maybe the best solution for weight and complexity was to just make the "front" of the spring longer so that it could be bolted to the somewhat beefed up cross-bar just below the rudder belcrank. I had 4 of these springs made and they work just fine. If you have need of a tailwheel spring, I can get you one for $28 plus shipping.
Another problem that I found earlier was the fatigue of the very last cross member of the fuselage due to the sideways forces of the tailwheel spring when you steer or "kick" the tail around. This piece of aluminum is about 5 inches long and is an angle bent to about 120 degrees. I now backed up this piece of aluminum with a piece of 3/32 inch steel bent just like the aluminum angle.
FIBERGLASS MOLDS
rdm
I'm not sure whether old age (yours or mine) has anything to do with it but I don't have as many fiberglass molds as I did earlier. I have been loaning them out to anyone who asks and suddenly I can't remember where they all are. Would you please check you storage areas and let me know what you have?
SPARS
rdm
Jim Bede was at Oshkosh this year and said that he was looking into making a spar buy. He did not have a price yet. He said he would be selling them through his son, Jim Jr. If you like the price and decide to buy some - please do not send money but only buy C.O.D.! If everyone does this he will be forced to sell that way or not at all.
Jim also talked about chemically milling spars to save weight. He said that they can be milled so they go from 0.120 just outside the cabin spar to.040 at the tip. This will change the weight from 27 to 18 lbs for each wing spar.. This is a total savings of 18 lb per airplane. The only drawback is the cost of $150 to $200 per spar. Before you opt for the tapered spar, it would be a good idea to look at all the extra weight you have already added to your airplane. It would be much more economical to take the 18 lbs out of the "frills" budget.
If anyone has an extra set of spars it would be a good time to advertise them. I have been getting a lot of requests for them.
LETTERS
A couple of people asked me why I didn't put their suggestions in the newsletter. The truth is that one envelope of about 30 letters got mislaid and I did a lot of looking before finding them. You have to realize that my filing methods have not been too organized during my move and house building activities. I'm sorry and will try to not let it happen again! I really appreciate the letters - keep your ideas coming in - they help everybody.
Bob Hoey sent in a method of keeping you doors from whipping off in the wind (see Figure 5). Bob also has tried the windshield comer deflector idea. He found no increase in speed but did get a quieter cabin and a lower stall speed. He theorizes that maybe the windshield vortex moving past the wing in some way as to give a premature stall. He thinks that stall is 3 to 4 mph slower. Figure 6 shows the method used to build the corner deflector.
Click on image for larger view
Bob sent information on AD 81-18-04 and AD 81-18-04 R1. These AD's have to do with the oil pump Impeller shaft wear and affect Lycoming O-235 through IO-540 engines of certain serial numbers. His O-360 was included and he had had it fixed. He recommends making sure your engine has the AD complied with.
John Raffensparger wrote to let us know that he is thinking of building a 1 place BD-4X. It will use a 115 hp engine and a 2 spar wet wing. Other wise it will just be a scaled down BD-4. This sounds like a fun airplane and could be built very easily. It could also use a Rotax engine to save weight. We in the Northwest have been thinking along the same lines but for a 2 place side-by-side with plenty of elbow and leg room. We have found that an Avid Flyer is really fun but way too small. If anyone is interested - contact John.
John Bracher wrote to say that he recommends Pete Grubb 619-588-0690, for propeller work. He is used to working with homebuilders.
For those of you who need a little more speed, Deane Ogden is now getting a 6 mph speed increase just by installing a crossover exhaust system. His cruise is now in the 190 mph area.
Glen Dickenson has lost his BD to a hangar fire and now has the following items for sale: Landing gear legs (7075 T6 milled from solid stock) for $300, new center spar $150, two each nose wheels and tires in yokes milled from 2024 AI with anti-shimmy dampners $200 each, 3200 Scott tail wheel and spring $250.
John Schippers says to check the roll pin in the attach bracket of the horizontal stabilizer. It should be there and it should be safety wired! The aileron balance weight should be checked to see that they cannot get caught in the wing tip. The first ones were built without the steel stiffner going all the way to the end. He doesn't knowif a Design Improvement was ever generated for this.
Paul Wood says he happened to talk to someone recently who knows of a pilot who flew a BD-4 cross country without a cowling. Has anyone else tried that?
Joe Lienau flew his BD in a 'CAFE 200' put on by his EAA Chapter (Downers Grove, IL). He won the 3 or more seal category. They plan to invite other chapters to participate in coming years. I would like to know if they weighed each airplane as they do in the -400? This seems like the hardest thing to do for a race of this sort.
Jack Hartman called to say that his BD is almost finished (he just missed Oshkosh). He has installed upswing doors and reversed his main gear legs to get some weight off of the nose wheel. He Installed two inch instruments and put them above the knob that controls ft. He wanted comfortable seats and' found the Pontiac Fiero seats were just right. They weight 35 lbs rather than the 14 lbs for the original seats.
Dick Gushman and Jim Parker have let me know that they have their ailerons set and that they came out with the correct deflection and differential. I am going down one of these days to see how they accomplished this! They are about ready to fly their O-360 powered BD very soon. They are worried about use of the small Scott wheel as a nose wheel. They would rather have either the larger Scott or a Murphy type wheel.
Paul Wood contacted me to ask about the ground handling of his tail-dragger. He has had a difficult time in getting used to it. He checked the toe-in of his gear and found that on one side the toe-in was substantial, and the other side had a slight bit of toe-out.
ed. notes:
The role here is that the gear should be
overall toe-out for a tail-dragger and toe-in
for the nose-dragger. The amount of toe-out
for the tail dragger should be very small
like 0 to 0.5 degrees. The toe-in for the
nose-dragger is not as critical but should
be small to reduce the rolling resistance
on takeoff.
When resetting the toe of your wheels it is not super important that the toe is compared to the fuselage sides as long it is alright compared to each other. "E" shaped pieces of aluminum can be used to shim the wheels straight. The two cutouts in the "E" are to go around the bolts that hold the axle on. If tire base of the axle is two inches wide, a piece of 0.025 aluminum will give a charge in toe of about: arctan (.025/2) = 0.72° (this will not be exact because the shim is not tapered - most likely, the angle will be greater than indicated). If you drop a plumb-bob from a 36 inch long straight edge clamped to the disk of the brake (and leveled), the correct toe-out would be a maximum (0.5°) of 0.31 inches in 36 Inches.
Another important factor in the ground handling of a tail-dragger is the stiffness of the springs used in the tailwheel steering. Do not use the "spring set" offered by the parts houses for such airplanes as the Cub or Champ. It Is much to soft and will give you a delay in moving your tailwheel when you give it an input with your rudder pedals. I find that very strong tailwheel steering springs greatly improve ground handling.
Paul Wood has a like new "How to Build Your Own Airplane" book for sale.
J. W. Brewer has an engine mound for sale for $125. it is for an IO-360 and uses the Piper Cherokee Lord engine mounts. He also has the following aircraft for sale: Stinson 108-1, Stinson 10, Cessna 170, Cessna 172, PA16 Piper, Ercoupe, Grumman Traveller, Breiglieb sailplane.
Bill Heine, 1095 E Idlewood Dr, Camano Island, WA 98292, PH 206-387-0822 has a BD-4 exhaust system for sale.
LETTER TO PRESIDENT PAUL
by
Monroe McDonald
Dear Mr. Poberezny,
I have returned from attending the '88 Oshkosh convention with my Bede BD-4 homebuilt aircraft and I wish for you to know that I am disturbed with what I see happening there.
Over the years I've seen so many airshows with hundreds of loops, and hammer-head stalls, that I would prefer to spend that time in forums, visiting exhibits, etc. However I feel I must spend the airshow hours guarding my plane from the hordes of general public that the EAA is admitting to the flight line. The homebuilt parking area seems to be the prime airshow seating They come with toddlers and children of all ages who run loose around and on the planes. They come with their food and drinks, baby strollers and lawn chairs. They sit their children on the planes for a better view, and they walk under the wings with their backpacks frames on. Several cigarette butts were found in the vicinity of the BD-4's; the wet wings don't leak badly, but they have been known to seep gasoline.. Any myth that these were "aviation" people was dispelled this year.
In our meetings, some plane owners said they will not bring "show" planes to Oshkosh again. Most of us want to keep coming, and are going to try using ropes and stanchions to protect our planes, although acquiring and carrying these things will be a burden. My question is, why is the EAA doing this to us? I am afraid the answer is that the big crowds that come to see the airshow, the Concorde, B-1 bomber etc., and the money they bring, are the main Interest of the EAA now, and the experimental airplanes are being trampled in the crowds. Witness the theme photo on the cover of the program book: the Concorde. it's interesting, but what has it got to do with homebuilts? The airlines and the military that you are featuring now are the ones trying to run us out of the sky. It kooks like they are already running us out of Oshkosh.
RIVETS
If you are looking for rivets, I found them to be very expensive and now may have found a better place to buy them. I finally found some Cherry brand aluminum pop-rivets in 1000 quantities for about $0.08 apiece. Some of the RV builders told me that they get monel pop-rivets of very good quality from Van Grunsvan. His price was about $0.06 a year or so ago - the best I could do in Seattle was $0.25 apiece. He might not sell to just anyone but an RV builder could get them for you.
HAVE YOU FLOWN A FORD LATELY?
During Oshkosh week several people asked me if I know about Ken Mitchell's Ford V6 powered BD-4. They had heard about him from Blanton when they called to inquire about powering the BD with a V6.
After returning home, I contacted Ken and after many delays with weather and other problems, we finally made the trip down to Utah. Jim Huber, Dave Dotson, and I made the trip in my BD-4. Dave has a BD just like mine and Jim is now running his RX-7 Mazda engine on a lest stand.
Ken's BD was started by another builder but Ken reworked the wings, finished the fuselage, and installed the Ford V6. Ken used a unique method of reworking the wings. He carefully took apart the fuel cell end of both wings, painted the insides with ProSeal and then put them back together again. If you use some heat, the 3M-2216 epoxy will come apart quite easily. I never did ask Ken how he got to the clamps on the wing where they are on the Inside of the fuel cells.
The first thing I did was to try to determine what the difference in speed would be if our two airplanes were putting out the same power. Ken has the original windshield, no main gear leg to fuselage fairings, no fairings over the brake modules, loose fitting wheelpants, no fairings on the tailwheel, and a lot of cowling (cooling) drag. I would estimate that there would be a difference of at least 20 mph and probably more like 25 mph.
The cowling is a standard Brekke cowl that has been extended 3 inches at the rear. The openings for air cooling the Lycomings were left open to cool the engine compartment and provide air to the carburetor. A 6 by 18 inch opening was placed below the prop shah for air to go through the radiator (Ken opted to put one radiator under the rear of the engine rather than use two at the upper sides of the engine). Ken first tried a 6 by 6 inch opening but found that on 100° F days the engine ran a little hot. This opening is covered by a medium coarse screen which restricts the airflow to some extent. Ken plans to change these openings when time permits.
The exhaust comes out of the cowling on the bottom side and turns toward the rear and somewhat toward the center of the fuselage and then goes all the way to the rear of the cabin. The pipe that comes out of the cowling and hooks to the straight pipes under the cabin is a piece of chromed flex pipe. Ken plans pack the long 'mufflers' with fiberglass to further quiet the exhaust. The noise level is no problem how. I like the idea of getting the exhaust behind the cabin area but I don't know if I could live with the drag. The flex pipes could be routed inside the cowl if it weren't for the radiator location.
The propeller is a Prince Aircratt Co with 'Q' tips. It is 68 inches long and has a pitch of 74 inches. That correlates to 190 mph at 2700 rpm (4320 engine) or 140 mph at 2000 rpm (3200 engine). Ken says that liftoff occurs at about 85 mph and 3600 rpm (2250 prop rpm). The gear-down ratio that Blanton recommends for the BD-4 is 1.6:1. This makes the two prop rpm numbers above, engine rpms of 4320 (2700 prop rpm) and 3200 (2000 prop rpm). The propeller is 1/2 inch lower than it would be if a Lycoming were powering it. Ken has a small 'skull cap' spinner on it for now and plans a much larger one later.
The weight figures come out very good. The airplane is painted has some fairings, a complete but not fancy interior and tips the scales at 1235 lbs. That is the Same as my O-360 with a constant speed prop, and a couple more fairings.
The engine of course is a Ford V6 of 3.8 liters (232 cu in) with 8.8:1 compression from a 1983 LTD. The carburetor is a Holly 500 cfm with electronic lean. The main jets are not yet right and the exhaust pipes are a greasy black from running too rich. Ken is a bit dissatisfied with the leaning. He now has it set for only rich or lean and it is not nearly adjustable enough. The igntion system is standard Ford with a magnetic pickup in place of points. There is one coil and two electronic ignition modules that are checked during runup. The plugs and ignition leads are standard Ford. The radio noise is very low even without shielded ignition. The proper radiator for this application is 37 inches by 6 inches, has 9 tubes and is a '4 core see-through'.
The reduction system is from Blanton and uses a cog belt and two aluminum pulleys. The belt is about 4.5 inches wide and Ken has 125 hours on it so far. There are no signs of wear and Blanton says they will last for many years. A possible advantage to this system is that the belt absorbs shock and does not pass it along to the engine or the prop. The structure of this system looks very beefy and probably could be judiciously lightened to some extent. A little longer prop shaft would help in filling a nicely faired cowling but is not bad as it is.
The engine mount does not look difficut but Ken gave us some pointers as to how to improve it. He made a litle error and had to mount his oil cooler on the fire wall as it interferred. Of course the mount comes right in front of the exhaust pipes and at least one of them on each side has to have a jog in it.
We flew the airplanes side by side to get a feeling for the Ford's performance. The cruise speed used was 146 mph indicated at 6000 feet (141 on Ken's) and Ken had about 3800, engine rpm and 22.5 inches of manifold pressure. I don't have a good feel for what Blanton says this should be in horse power but some of the data he has put out shows that 3800 rpm and 17 inches of manifold pressure is equal to 118 hp. The actual horsepower I had to set to keep up with Ken was 50 % or 90 hp.
The only way I can guess at what horsepower he was putting out is to do the "speed change is proportional to horsepower change cubed" comparison. If my analysis of the extra drag on Ken's airplane is correct in that it causes him a 25 mph speed loss, then he was putting out enough hp to go 25 mph faster than me or 170 mph.
hp needed to go 170 = 90 mph (170/145)3
This works out to be 145 hp. 145 hp out of the V6 is shown to consume 7.2 gph which is about what Ken says he bums (70 minutes of flying, 2 touch and goes uses about 7.4 gallons).
I know, I know! What does it cost? Ken has $1100 in the engine setup, $2000 in the reduction system and Blanton plans, and $500 in his prop (could be as cheap as $300). This grand total of $3600 is just a little over what a used constant speed prop will cost you.
I lucked upon a 1987 Ford LTD V6 just yesterday with only 6000 miles on it. I talked them down to $450 and bought it. I am ready to be disappointed with the take-off performance of a fixed pitch prop but am really looking forward to working with this engine. It weighs 293 lbs at this time. That is the basic engine without carburetor, exhaust system, alternator, starter, flywhel or reduction system (59 lbs). Blanton claims that the ready to fly system weighs 387 lbs This is 14 lbs heavier than what Blanton says the Lycoming O-360 weighs. I just weighed my O-360 engine and found that everything forward of the firewall except the cowling was 416 lbs. That is including a Hartzell constant speed prop and spinner of 59 lbs. It appears that Blanton's engine weight numbers are very accurate.
I have a great idea as to how to get a constant speed prop to work oh this engine. Just use a standard Hartzell and rebuild it to be electric driven using slip rings. It should only take a couple of years to get it going! We are planning to tear down McCawley and Hartzell props to see it ft is possible.
Click on image for larger view
MEMORIAL DAY FLY-IN
We held the third annual Memorial Day fly-in at my place and as ususal we had a great time eating, talking, playing volleyball, flying and hangar flying. We had a disappointing turnout of BD-4's but Steve Mahoney did a great job of giving rides - thank you Steve!
We had 42 people there representing 13 BD4's.
We have this get together every Memorial Day so plan on coming up this way for a fun day. We can put up some people if they would like to stay overnight. We do a potluck for lunch and usually eat about 3 PM.
OUR CONDOLENCES
We are very sad to have to announce the death of Dick Penney of Fort Worth, Texas. Dick has been a strong advocate of the BD-4 for many years and we will sorely miss his companionship. Although he did not get his BD finished, he had great fun in planning all the improvements he was going to make. Warren Sambell of Arlington, TX now has Dick's BD-4 and is continuing the building process. He had worked with Dick over the past year or so.
BD-4 PLANS
Since there are no plans available for the BD-4 and I can't trace the rights to the "How To Build Your Own Airplane" hook, I have found a place that will make copies for you. They will be on 11 by 17 inch paper and will be unbound. The price is $35 per set.
J.R.'s s METAL WORKS, INC
PO BOX 61
BROOKLANDVILLE. MD 21022-0061
Dear Fellow BD-4 Enthusiast:
After several false starts over the past five years, I have finally started fabricating parts for the "4". I hope to make available all of the metal parts and fasteners along with building tips and advise. I will not be able to offer plans for now, but there should be many sets available through ads in Sport Aviation, Kit Planes or Trade-A-Plane. I will not get into suppling wheels, brakes, cables or other hardware items which are readily available from Aircraft Spruce, Wicks or one of the other good suppliers in this field. I will however, soon have a list of all these parts.
I am initially offering formed pans and a Fin and Rudder Kit. A Stabilizer Kit will follow this fall and I will base further offerings on demand. A Metal Wing Kit and Spars are a possibility, but it will probably take firm commitments from 10 or 12 builders to meet the minimum purchase requirements. I have made several sets of hand formed ribs for builders, but my delivery time has been too long, so I am looking into having wing ribs hydroformed. I plan to otter only parts that I have in stock or can complete in no mare than two weeks. Once you get to building no one wants to wait.
I now have over 200 hours on my BD-4 N643R and am extremely happy with the bird. We have been to Oshkosh, Sun and Fun and numerous other fly-ins. It took approximately 3000 hours over 6 years to construct my plane, however, I did Alodine and Zinc Chromate the entire airframe and I constructed two sets of wings. The first being the Fiberglass ones. While sanding these I experienced a 40% bond failure in the epoxied joints of the panel ribs. l reluctantly sawed up $500.00 worth of fiberglass and set about designing a metal wing using plans for the BD-7 as a guide. I have never regretted building the metal wing. There has not been any fuel tank leakage nor any fuel flow problems in seven years.
The first 30 hours of 643R flying time was spent as a nose thumper, then a friend who was doing my flutter test, bent the nose gear strut. Atter talking to several other owners I decided to convert "Bird" to a tail dragger. This turned out to be another good decision as I have had no trouble at all with this installation.
My "4" has a 150 hp Lycoming and cruises at 140 mph at 2500 rpm. This is somewhat slower than advertised but the best I've heard for a 150 is 150 mph. Many of the builders with 180 hp report cruise speeds of 180 mph. I will try to work up some comparison's for you The 150 hp BD-4 can gross out at 2000 pounds, while the 180 can go to 2200 pounds with a landing weight of 2000, this Bird will carry just about anything you can stuff into ft.
As time permits I will work up more interesting information on the BD-4 and send it to you, if yuou have any questions please feel fee to write or call evenings (301)-343-1079 (home).
Happy Flying,
John H. Raffensparger
The following items are available from J.R.'s Metal Works:
BD-4 Newsletters
I have photocopied 21 BD-4 Newsletters, these contain a wealth of information including history, building tips and builders. Post Paid $25.00.
BD-4 Design Improvements
If you have BD-4 plans without the DI's you are missing a lot of very important information. There are several DI's that are mandatory and could affect flight safety. Post Paid $25.00.
Large Fin and Rudder Kit
Includes formed Fin and Rudder Skins, 3 formed spans, material for ribs, fasteners, hinge and miscellaneous materials. $275.00 plus $10.00 for shipping and handling.
BD-4 Formed Parts
| 2 | Fuselage side channels | 2024-T3 | $82.00 |
| 1 | Main gear box | " | 33.00 |
| 1 | Gear box cover | " | 18.00 |
| 1 | Gusset material, 12 ft2, 0.063 | " | 76.00 |
| 1 | V angle 41.5" long | " | 13.00 |
| 1 | 122° angle, 46" long | " | 15.00 |
| 2 | 76° angles, 48" long | " | 27.00 |
| 1 | Formed angle .063, 2x2 by 72" | " | 12.00 |
| 1 | Formed angle .063, 1.5x1.5 by 72" | " | 9.00 |
| 1 | Formed angle .063, 1x1 by 72" | " | 6.00 |
| 1 | Strip .063, 1 by 72" | " | 3.00 |
| 5 | Angles .025, .75x.75 by 42" | " | 18.00 |
| 1 | Stainless Steel .016" firewall | SS | 40.00 |
MS21040-3 Nuts: 109.00 per thousand, 12.50 per hundred.
Add $5.00 to material orders for UPS and
Handling.
Please give shipping address! Foreign orders
add postage for preferred method of shipment.
jhr
FIBER-GLASS PARTS
I've had a lot of requests for fiber-glass parts from the molls I used for my airplane. I will make these available to you it you don't mind trimming and putting things together. The cowling will come without flanges (you can put on metal or fiber-glass, or hinges). The wheel pants and wing lips will come untrimmed and the two sides not glassed together. The easiest way to get this done is to trim the part to the edge of the mold line, tape the halves logetherwtth Duct tape or better, and then laying a couple of strips of 8 oz glass in and brush on polyester resin.
| Cowling | $400.00 |
| Wing tips (pair) | $150.00 |
| Tail (or nose) wheel pant, Scott 3200 | $ 50.00 |
| Wheel pant, 600 x 6, Cessna type | $150.00 |
| Wheel pant, bottom enclosures (pair) | $ 45.00 |
All items are shipped the best way and will be Freight Collect. rdm