BD-4 NEWSLETTER #24, March, 1996
Roger D. Mellema
17605 SE 288 P1.
Kent, WA 98042, Ph: 206-631-5324
rmellema@halcyon.com (or: rmellema@atc.boeing.com)
http://www.halcyon.com/rmellema/bd4.htmi
(ready soon)
Dues:
The number before your name on the address label tells you how many issues you still have coming. The cost per issue is $2.50.
Greetings!
The time for getting a newsletter out has come and gone again but there is some really good news in this issue. There is now an option for getting spars for the new builders - my, but we have been waiting a long time! Better yet, the new cabin spar is much stronger and can be substituted for the spar in our "already flying" airplanes. This will allow us to put on a little longer wings and still be safe.
Things have not been progressing much on the home front as Boeing is really getting into MY time. The DarkStar UAV has not flown yet but will within the month. It has been making lots of taxi runs at Edwards AFB and the software control algorithms continue to be refined. "My" radar is coming along well in development tests at Baltimore and I expect delivery within a month. I expect to fly the radar on the DarkStar during Oshkosh '96 (snif snif snif). It looks as if there is no way I will get there this year- I cant believe missing two years in a row. Boeing really really owes me! (hear them laughing?)
I had a small failure with my V-6. A tiny piece of gasket material (RTV) caused the oil pressure regulator to hang up causing low oil pressure. There was no damage (crank bearings) and the airplane is ready to fly again. There was also a problem with the small hardened steel clip that snaps over the hex shaft between the distributor and the oil pump It had come off and gotten chewed up by the timing chain There was a little pitting of the lower sprocket so it got changed out too. Boy, is it nice to be able to afford the price of engine parts!!
Spars! (Dream Aircraft, Inc.)
There is now a solution to several of the problems faced by BD-4 builders. A company in Grand Rapids Michigan has designed and is producing aircraft components, some of which may be interchangeable with the BD-4.
The "Super Tube" spars look like they can be made to fit which solves the major problem in building a BD-4 from scratch - the non-availability of spars. Several aspects of this new center section will work to our advantage. This spar is longer and stronger which answers the wing extension beef-up we have been faced with solving. It would be nice to pull out the existing cabin spar and replace it with the new higher strength spar.
Dream Aircraft offers a choice of spar packages:
- two, 12 foot wing spars and a Super Tube@ center section
- two, 10 foot wing spars and a Super Tubes center section.
The price quoted to me recently is very good and knowing the people involved in this company, I am confident that you will be treated properly. I am buying a set of spars just in case I want to change wings and want to continue flying while building. I am also considering changing out my cabin spar which I have not yet beefed up to allow flying at high gross weights with my already extended wings.
If you are interested in a set of Super Tubes, please contact:
Scott or John at: 616-454-7747, Fax. 616-776-0224
Dream Aircraft, Inc.
188 Wealthy SW
PO Box 1923
Grand Rapids, MI 49501-1923
188 Wealthy SW
PO Box 1923
Grand Rapids, MI 49501-1923
More spars:
Dave Downey (a fellow Boeing employee from Philadelphia) has an intense interest in carbon fiber spars for the BD-4. They offer some real advantages in weight and strength. The applications brochures he sent show carbon drive shafts for dragsters and also for huge garbage trucks. I am sure it would work but don't know the price. Will keep you updated.
Needs:
|
Aluminum Welding
Someone (sorry, I couldn't read my note) called and told me that they found the answer to welding aluminum. Call: GLIB Welding Equipment at 800-258-0126. Their techniques were so effective that you can easily use the Henrob (Dillon) torch.
Subaru SVX engined BD-4s:
Cordon Merrow (42772 Almond Grove Cir., Murrieta, CA Ph: 909-677-5868) is working on fitting n SVX engine in his BD4. Chapter 286 is assisting (we would like to hear more about this).
Bob Reynolds (#7 North Winds Dr., St. Peters. MO 63376) is putting the new flat 6 cylinder SVX engine and an RFI PSRU on his BD-4. This is a first, I believe and should be interesting. Good luck!'
Synchronous Belt Tension:
Machine Design (April6, 1995) carried an article by Gary Porter (Application Engineer, Gates Rubber Co.) that spoke to synchronous belt tension adjustment. Those of us with belt PSRUs have all worried about just what is best.
The article stated what we already knew, that if the belt is to loose, the belt will ride up and out of the sprocket producing excessive wear and cracked teth. If the belt is too tight, there will be undue stress on the drive components.
Belt efficiency (power loss) is worse when the teeth are not fully engaged. The ideal tension is when the belt rises slightly off the "back side" of the driven sprocket under normal loading.
There are ways of determining the best tension but none are easy on an airplane. The easiest thing that comes to mind is to position a micro switch (or a series of them) on the slack side of the driven sprocket and see how much the belt rises. Some manufacturers offer software and publish tables to simplify tensioning based on geometry, speed, and design load. I will see if Elwyn Johnson of NW Aero can get this software.
The chart below shows four initial static settings and how the tension changes with load. At the high setting, the belt showed little tendency to ride out of the sprocket as the torque load increased to approximately 180% of the belt rating. Even at that level, initial static tension plus self-tensioning of the belt under load increased teh total tension very little.
The belt does "self tension" but if you look at the "100% of belt rating" point, you can see that the belt tension is about the same for the three lower tensions. This means that the belt is being stressed about the same anyway, i.e. you might as well tension it correctly (the wide line).
Now that we know all there is to know -------we have to deal with the fact that the PSRU does not always run at the same temperature (thermal exansion)--------and sometimes the back "plate" is hotter than the front plate. Ah, but for a good challenge!!
SuperCharged Ford Information:
Charlie Rosenzweig (9070 Ocean Beach Hwy., Longview, WA 98632-9752, Ph: 360 577 6407) passed along the following sources for information on the SC engines. Rebuilt SCs are available from: Magnuson Products, 3172 Bunsen Ave., Ventura, CA 98008, Ph: 805642 8833
| For articles on SCs: Super Ford magazine
(jan & May '95), call: 800 883
4561 For the T-Bird newsletter "TIX", call: 602 948 3996 For the 3.8 V-6 STOL newsletter: Bruce Frank, 218 Landenberg, Landenberg, PA 19350. This is an excellent newsletter with a lot of people taking part in the information exchange. |
John Steers Progress Report:
John reports that he has been making good progress. JR Metal wing with 22 inches extensions. The 96 inch flaps are made from 2.725" x 0.035" tube for leading edge and ten aluminum ribs. The flap actuator tube extends through three of the ribs to better distribute actuator loads into the flap (a good idea for extended flaps - ed.). Two Delrin AF rings were used as center bearings. All modifications were made to allow 40° flap deflection (excellent idea, be sure to increase size of gussets #61 and #62, BD4-1-07 - ed.).
John uses a gas spring to hold up his top hinged doors and is planning to power his BD with a Super Charged Ford V-6 with a NW Aare PSRU.
BD McMelbrider Ford Jr. (Jim McDougall):
My BD-4 is faking shape at the usual snails pace; in 450 hours of building and at least as many hours of planning and thinking, I have an almost complete basic fuselage (enough to sit inside and make airplane noises). My method of construction is to build for a while, then disassemble the parts, debut holes & sand the sharp edges, apply a coat of Dupont epoxy primer, then reassemble. This method is slow but the resulting airframe is well protected and looks more like a pro built it.
I am not sure that I can still call my project a BD-4. Major changes planned or completed include:
- I extended the cabin by 18" as suggested to balance the heavier engines.
- I widened the back seat area and raised the root using Lloyd Brekke's plans
- Will use Cessna 172 flat spring landing gear per Hugo Schneider's design.
- Will use metal wings per John Raffensparger's plans.
- Will use new aluminum wing spars of my own design.
- Will use the rounded windshield designed by yourself, Roger Mellema.
- Will use an automobile engine, probably a Ford V6. Maybe I should call my plane a BD McMelbrider Ford Jr.!!!
1 read with much interest Steve Mahoney's report in the last newsletter. His computer analysis of the BD-4 spar shows that if you are using long wings, you must extend the cabin spar at least 12 inches on each side. I took initiative tram the article and decided to design my own spars.
I chose a 6 inch schedule 40, 6061 T6 aluminum tube. It is of standard dimensions, readily available and not expensive. The OD is 6.625" and wall thickness is 0.28", 40 % thicker than the original cabin spar. I plan to use the tube full thickness for the cabin spar and machine it thinner for the outer wing spars. I plan to join the spars outboard of the fuel tanks. My spars will be heavier than the original spars and should be at least as strong. I would like to see an engineer check it out. (I called Jim as to the new Super Tube® available soon from Dream Aircraft).
On another topic, I am in need of a tailwheel and main wheel parts. I can use either the Scott or Maule 8" pneumatic tailwheel assembly, a 1 1/2 inch wide tailwheel spring, and two Cleveland 6.00 * 6 wheel and brake assemblies. I have four Goodyear 6.00' 6 wheels to sell or trade. My phone number is 306-554-2551 work or 306-328-4847 home, fax is 306-554-3851.
Second!! BD-4 (Joe Lienau):
I read with much interest the article on spar loading in your most recent newsletter. I have purchased Francis Longs wing ribs and flanges, they are beautiful!!! 99 % of all the work is completed. All the builder has to do is cut the lightening holes where there is no fuel tank area and cut the holes for the spars. I feel they were worth every dime paid.
I am getting serious about working on my second BD-4 and am making some changes as follows:
- Extending the fuselage 18" (using a side channel 78 inches longer).
- Extending the wing two bays on each wing.
- Covering the forward fuselage (and belly) area with 0.032" skin.
- Using 7075-T6 main gear legs (I have these already).
- Installing skylight window over aft cabin.
- Adding one window on each side (like Ray Ward's).
- Installing a Lycoming 0-540-A (235 hp).
- Aluminum wing.
P.S. I have ordered a Light Speed Engine solid state ignition system for my current BD-4, but understand it can be a little tricky installing the trigger pins on the starter ring gear.
Is it time yet (to join the "Information Super-Highway")?
I almost hate to broach this subject as it seems to make people either a bit defensive or apologetic. The Internet is really a great thing and it will be geeing better all the lime. The problem is that it does cost a good bit to get "connected" and you have to do a bit of learning to feel comfortable at "surfing the net". Take heart though, as the Internet is getting MUCH easier to use with the new software.
The Internet
The Internet is the original structure for
communicating between computers in government,
universities, and industries. It includes
methods of exchanging data between computer
systems chat frequently were designed independently.
As a result, there are several protocols
that are necessary to understand if you want
to interface with "everyone". Fortunately,
most of us don't have the time or the need
to get into every tile at every site. For
starters, it is best to begin working with
the World Wide Web which is the newest addition and probably
the "solution" to the wide variety
of transfer protocols on the net. It has
"search engines" for finding information
on specific subjects and is also set up to
transfer data from the source to you. It
is an interactive system that allows you
to just "click" on something you
are interested in (usually a "highlighted"
word) and the software does all the hard
work in getting it for you.An example to entice you: in about 3 minutes an "N" number search program on the WW W found the current owners of all my old airplanes. The same program found all the airplanes registered by the FAA under "BD-4" or "Bede".
You will have to decide which "service" to buy. The Internet is the oldest and was once dominated by the government, universities, and industry but now there are many suppliers offering partial Internet access. You can get partial access through many other on-line services (Prodigy, America On Line, CompuServe, Delphi, GEnie) but for my money. I want to be on Internet (I have not cried all the other services so make your own derision). The other on-lines services had an advantage in that they were initially more user friendly. They soon found out that they had to have a "window" to each other and to the Internet so that their customers could communicate freely. The new software available for working the Internet makes it a big contender for "king of the hill". Pick the service you want but make sure it allows you to access the Internet.
E-mail
Most of you will also want to use the e-mail
system for talking with friends. The original
Unix mail system is hard to use and the editors
that they employ (vi) are straight out of
the dark ages (elm and pine are two "somewhat
improved" mail systems). New mail software
such as Eudora really make the e-mail system
work as it was intended.Usenet News
Another feature of the Internet is Usenet
News - The news channels (rec.aviation.homebuilt
and others) are great for interfacing with
others of a like mind. You will have to be
the judge of the quality of the answers given
but they can be enlightening and entertaining.With Usenet News, you will be able to read what others write and if you like, you can post an answer or a comment. This is not a real-time "chat" channel. Your post may take several hours to get on the news.
Computer equipment
The computer required for operation on the
Internet can be very inexpensive. The rate
at which data can be pushed over standard
phone lines is quite slow and it does not
take much of a computer to "keep up".
A Macintosh SE or an IBM 286 (or compatible)
is probably the absolute minimum you would
want to buy. They are very reasonably priced
on the used market. If you are going to use
some of the modern software to make it easier
to use the Internet, be sure it can run on
the machine you plan to buy.You will need a modem (which means "modulate-demodulate") to get the bits and bytes (8 bits to a byte) to flow over your phone line. The slower modems (2400 to 9600 baud) are almost given away, the 28,800 baud modems sell for $130 to $200. By the way, baud stands for "bits audio" per second. It you want to be on-line the shortest time possible and it you want to download graphic and pictures from the World Wide Web, you really need the taster modem.
Cost
The monthly cost of an Internet account is
actually quite reasonable. I have an unlimited
time, enhanced software account chat runs
$22.50 (Boeing discount, normally $30). If you don't mind using the archaic Unix language, the cost can be much cheaper but it will take some time to acquire the Unix skills. If you are into pull-down menus and great graphics (Macintosh and Windows) you definitely don't want the basic Unix "shell" account. Most of the software you need for enhanced Internet operation is available as shareware or you can buy collections of shareware wish documentation for ~$30 (this also allows as much as 14 days free use of the Internet).
If you want the e-mail options and don't do much "surfing", you can get enhanced accounts that run $9 per month for 9 hours ($30 to $50 setup fee and $1.50 /hour over the 9 hours). An inexpensive account is a good way to go but you must remember to compose your letters "off-line" so as to not incur cost while you are thinking.
A good way to team about the Warner is from a friend who is well versed or by taking a night course.
The Australian Connection:
Dave Sharpies (22 Coppabella Cr., Mooloolaba 4557, Australia) has been working for the Gliding Federation of Australia in developing an automobile engine to replace the Lycoming 0-540 that power their PA 25s (Pawnee) that are used for towing.
They made the mistake of ordering engine and PSRU from the US so as not to "reinvent the wheel". They were disappointed in the "level of engineering ability in America". It is unfortunate that they got sucked in by people who definitely were not "engineers".
They have gone forward and modified the Ford 3.8 L V-6 and obtained some impressive results. The largest problem that had to be solved was the unequal fuel distribution to the cylinders by the intake manifold (1984 model). It is specifically tuned for lower rpm than is used in the airplane application and does not work well above 4000 rpm. They ended up making their own manifold and mounting twin carburetors. With this configuration the V-6 was dyno'd at 196 hp (8.6 to 1 compression). The 0-5408 was dyno'd at 190 hp (supposed to be 235 hp).
They have done extensive flight tests and the V-6 performance is indeed equal to that of the 0-5408 but the fuel usage is substantially less. They are very happy with the capabilities of the V-6 and especially like the liquid cooling for their glider towing application.
I have found that the fuel distribution using a 1986 intake manifold is quite good. I will have to study this a bit more in the interest of improving fuel economy. Fuel injection sounds like a great idea considering all the trouble these chaps went through to get a manifold that would work with a carburetor.
Oil information:
There is a unbelievable amount of oil "misinformation" that resides in our collective "knowledge". There are all the arguments about which break-in oil to use, whether or not to use 50 weight (auto) oil in a V-6 converted for airplane use, which (if any) additive is necessary, how often to change oil, etc.
There was an article in the General Aviation News 8 Flyer recently authored by Kas Thomas (editor of TBO Advisor). The article rites recent studies that show the mufti-grade oils as not being as good as plain old SAE 30.
"Now it turns out there may be solid scientific evidence that single-weight oils protect engines better than their multiviscosity counterparts. A recent study published by the Society of Automotive Engineers (the folks whose initials adorn the top of every can of oil sold in this country) casts doubt on the theory that multigrades are better all-around lubricants than straight-weight oils."
"Last March, Mercedes-Benz engineers Rudolf Thom and Karl Kollman, along with Shell Oil engineers Wolfgang Warnecke and Mike Frond, authored SAE technical paper 951035, which discussed recent research results involving a variety of oils. Among the many interesting findings presented in the paper was a graph showing cylinder-wall wear rates versus cylinder wall temperature in an operating engine."
'Three tests in a 2.4-liter, four-cylinder Mercedes-Benz OM 616 engine compared three kinds of oils. In one test sequence, a straight 30-weight oil was used; in another, 10W-30 multigrade; and in the third, straight 10-weight oil. In each case, the engine was operated at fixed speed, torque and temperature conditions until constant wear rates were observed. Wear rates were then plotted against cylinder wall temperature."
"While two of the oils turned in very similar wear performance, one oil stood out as protecting the engine against wear at the extremes of temperature. That oil was plain SAE 30 (straight-grade 30-weight). At either extreme of temperature, the maximum wear rate with 10W-30 was more than double that of the straight SAE 30 oil. The worst performance was turned in by straight 10 weight."
"These finding should come as no surprise because , in general, thicker oils make for thicker oil films and the thicker the oil film the better the wear protection. What's surprising is that a 10W-30 oil, which is supposed to have viscosity comparable to an SAE 30 oil at high temperatures, does not provide wear protection at least equal to that of a 30-weight unmodified oil. The simplest explanation, it appears, is that the base stock from which a 10W-30 multigrade is made (namely, 10-weight oil) is fundamentally not as good a lubricant as a 30-weight base stock. If would also appear that viscosity-index (VI) improvers are not, in and of themselves, robust lubricants."
It should be noted that some multigrade oils are made from base stocks that have higher viscosity than 10W. Shell's 15W-50 starts life as an SAE 30 and Phillips X/C starts life as a 20-weight.
Notes:
- This quick-drain allows you to get all water out of a non-sump type tank.
- On a high wing aircraft there is nothing protruding to cut your head on.
- "O" ring can be replaced through the drain hole (use a bent wire).
- Drain can be bonded to fiberglass or aluminum tank (no rivets needed).
- "O" ring is "Evinrude" quick disconnect gas line replacement ring.
- Be sure to corrosion-proof the 4130 steel or the seat will rust and then leak.
- The drain can be turned from aluminum or made from stainless steel.
- The seat can be cleaned by pushing up the valve and "scrubbing" the seat area.
- Be sure to use a strong enough spring or leaks will be frequent.
- The drain can easily be removed by "cutting" the ProSeal around the base.
- Use roSeal sparingly when installing to avoid "squish up" in front of drain holes.
Nose Gears:
Jim Murphy and Val Barnhardt systems are better than the original Bede system. The Bede system actually works quite well. The only drawback is that the nosewheel is a Scott 3200 and is a little small in diameter. The weight on the nosewheel should be carefully limited as some builders have had main castings crack. The nosegear should be carefully checked on each pre-flight as it is very important to the longevity of your arplane. Check the nosewheel by taking the weight off of it (have someone push down on the aft fuselage), and then attempting to swivel the wheel by hand. It should be quite difficult to swivel.
Most tailwheel shimmy quite easily if the design geometry is wrong (most are) or if the friction device (Scott #3234, thrust plate) is mis-adjusted or gets grease on it. The Scott 3200 friction cannot be increased by tightening the main pivot bolt. The assembly must be disassembled, degreased carefully, and the condition of the "thrust plate" checked. The "thrust plate" is held under pressure (against Scott #3207, washer) by several small springs (Scott #3233, spring compression). If there is not enough friction, either install a new thrust plate, install stronger springs, or the existing springs can be raised by putting something under them.
.c.Nose Gear, Murphy:
The Murphy brothers started building BD-4s right when Jim Bede first sold plans. They did a lot of work on improving the airplane but some of the improvements were of a type that most homebuilders could not accomplish in their home shops. This gear was sold by Jim Murphy to many builders. Jim is now totally our of the business but the drawings below show the technique used in the "Murphy Nosegear".
The following is quoted directly from the
Murphy plans:
The nose gear replacement kit is designed
to give the builder that has his or her BD-4
finished or nearly finished an easy way to
replace the small nose wheel and/or thin
wall strut with a 0.125" wall strut
without great difficulty. Many of the parts
are interchangeable and fit right in the
fuselage withoug modifying it.
The main difference in the two systems is
that the replacement strut is in a more horizontal
plane and is rigidly mounted to the fuselage
with a 500 x 4" Goodyear wheel mounted
in the castering fork.
When you hit a large bump at high speed the
strut will flex up and the pudgy tire will
help absorb some of the shock. When you hit
a large bump with the stock system with strut
mounted more vertical towards the center
line of the little 10" diameter tire,
the shock goes up the center line of the
tube right to the bushings, distorting them.
The wheel does not have tme to accelerate
over the bump, working something like a karate
chop. Notice the axis center line (pivot
oint) of the stock system and you can see
that the wheel has to accelerate over the
bump (or jump forward). A tail wheel or a
trailing suspension when the wheel hits a
bump the wheel will actually pause and lift
over the bump. The pivot point housing only
being 10" wide and the strut is 34"
long from the pivot point to wheel so any
play in the bushings will be comounded by
ration 3.4 : 1. When the nose wheel starts
to flutter it is encouraged by the play in
the strut. The fixed system does not have
bushings and is supported as far out as where
the shock was.
The nose fork is tilted forward 7° and
has a large 1.5 i.d. bushing on the full
tube diameter plus a simple drag clutch making
the flutter possibility very low.
Disadvantages: 1. The larger nose wheel will
cause more drag. 2. It is difficult to push
the airplane backwards. 3. It is expensive
to replace something that you have already
paid for. 4. Takes all the excitement out
of your landings - you do not have to worry
abut breaking off the nose strut or having
shimmy! 5. Lets you have confidence in making
short field landings in fields that you may
not get out of.
The following are building tips for the Murhy
Nosegear:
- Make nose gear as shown except heat treat.
- Make nose wheel fork as shown above.
- Assemble nose wheel and tire on nose gear. Afriction washer must be placed above the spring loaded steel ring that fits on top of the fork and also below the fork. These can be made of micarta or of heavy rubber belting or tire material. The inside of the bronze bushing is lightly greased but no oil ro grease shuld be on the friction washers. It should be difficult to swivel the fork on the strut by hand.
- Install nose gear and wheel on airplane with airplane blocked up so as to insure proper attitude and propeller clearance.
- Make the structure that replaces the delco shock using LGN-10 to hold top of structure.
- Remove welded assemblies ahd have them heat treated and magnetically inspected.
- Paint assemblies except where nose wheel frok fits and isntall in airframe ermanently.
- Make schckles - drill only the holes in the end that bolts to LGN-14.
- Make a three inch long transfer unch out of some 3/8 steel rod.
- Put one shackel on LGN-14 and align with nose gear assembly. Slip punch through hole in nose gear and punch location of hole into one shackle. Remove shacklw and repeat operation on the second shackle. Drill holes out of airfram.
- Install shackles.
Nose gear modification (Val Bernhardt):
Early BD-4 builder Val Bernhardt decided
that the Scott tailwheel "nosewheel"
was too small so he designed the following
modifications. Val's design is nice as it
takes very little machining and yields a
very robust nose wheel.
The 5/8", 4130 steel rod is sometimes
replaced with a thick strap of steel (1/4"
thick? by 1" wide?). The "strap
might be easier to weld to the vertical spindle
and the axle hole can be drilled right in
this piece.
If you notice the "backward angle"
of the axis of swivel, it should be noted
that this is the zero weight position of
the nose gear strut. When moderate loading
occurs the "axis of swivel" should
be vertical.
