SMALLnet post454

John E. Brodbeck, Sr., who was one of the greatest pioneers and manufacturers in the hobby industry, passed away on November 2, 2004 (while SMALLnet was not posting). John was represented by the "B" in the world-famous K&B trade name for model airplane engines. It was K&B that initiated "1/2A" modeling back in 1948 with their breakthrough K&B "Infant" .020 glow ignition engine.

This contributed greatly to the phenomenal glow ignition revolution in model engines that occurred after WWII with Ray Arden's development and marketing of the glow plug in 1947.

Therefore, we SMALLsters owe a LOT to John Brodbeck Sr. for his great contribution to our S.M.A.L.L. part of the model airplane hobby, by introducing "1/2A" in 1948. John will be dearly missed -- especially by us older SMALLsters.

I was only six years old in the late 1940's when my brother and I owned a Testors Baby Zephyr free flight model powered by one of John Brodbeck's very first production K&B Infant .020's. Sounds hard to believe, doesn't it? As has been said before, sometimes the truth is stranger than fiction.

In the mid 1940's, after my late uncle came back from World War II, he gave my brother and me small black silhouette airplanes that the military used for aircraft recognition training. For a pre-school kid these were great little "toy" airplanes. My brother and I "flew" them BY HAND for many hours around our parent's yards.

A couple years after WWII my uncle said he had a secret he was keeping. He really built up the suspense! Finally, one day he asked, "Are you ready to know my secret?" Obviously, by this time we were dying to know his carefully-guarded secret and didn't hesitate for a moment in responding with a resounding "YES". Man, were we primed! He told us to come over to his house next door and he finally would reveal his secret.

When we arrived at his house, he told us his secret was upstairs in his attic. As we climbed those stairs, the mystery intensified. Our curiosity was nearly overwhelming! What our astonished eyes beheld on the floor of that attic on that day in the late 1940's was a beautiful U-control biplane -- the VERY FIRST ONE of the many that we would later see in our lifetime.

You can imagine the excitement we experienced on that day -- at that moment -- especially with little kids our age. However, my uncle then "hyped" the excitement! He asked us if we wanted to hear and see the engine run. By this time we were bouncing off his attic's ceiling with excitement! My uncle then took out some fuel, a battery and a large syringe with a hypodermic needle to prime the engine. When he pulled out that syringe with that long sharp needle our eyes almost popped out of our heads! (Our uncle worked at a local hospital. He was used to being around lots of "hypo's". We weren't!! Nevertheless, we calmed our nerves. We were not about to miss this show! He then fired up the biplane's engine.

Man, what a roar we heard in that small attic, and then exhaust smoke everywhere! Whew! But what a show!! We were beaming! My uncle asked us if we liked the plane. We said we LOVED the plane!! He said, "It's yours!" Remember, our uncle also LOVED to give us gifts. He was a great uncle!

IN REMEMBRANCE OF John E. Brodbeck, Sr. will be continued in the next SMALLnet posting. Roger

...Roger, I have plenty of reminiscences about Johnny Brodbeck too. Johnny shared with Roy Cox the reputation of being the nicest guy to work with -- and to work FOR -- in the hobby business. I did both, with both of those guys; and their reputations were well- deserved indeed.

I'll just mention two examples of Johnny's unselfish service to modelers. Each year while the U.S. Navy hosted the AMA Nationals, Johnny set up -- and personally worked at -- a free engine repair station. He didn't just service K&B motors, either ! At his own expense, Johnny stocked up on parts for Foxes, McCoys, and other U.S. engines. He (and his helpers, of which I was one a couple of times) would fix any balky or crash-damaged engine that a contestant brought in. And if the engine was a K&B, damaged too badly to be easily fixable, Johnny would provide a NEW specimen -- one that was already broken in ! Free......

One more: After their overwhelming success in control-line speed competition, the southern California FAST Club (First All-Speed Team) found all-out contest flying both boring and too restrictive.

They then came up with the Team Racing concept; which was meant more for fun than trophy-seeking -- flying realistic-looking control-liners under conditions somewhat like the then-popular full-scale "Goodyear Trophy" racers.

At first Team Racing did just what the FAST guys intended. But soon the competition lust degraded Team Racing to just another high-tech, high-pressure contest event that nobody flew for fun any more.

Once again the FAST guys innovated. This time they came up with a NON-racing control-line type of flying. This was for scale Schneider Trophy seaplanes. The motives were several: (1) Just to see what could be done; (2) provide a challenge to the club members (each was required to choose a different design); and (3) to put on spectacular demonstration flying: taking off from, and landing on, a quarter-circle water tank -- and flying three or four of these sleek seaplanes at once in the same circle.

But I've drifted off into another of my digressions... What I wanted to say was that Johnny Brodbeck provided the engines for these control-line seaplanes. Free. They weren't stock, either. I'm not sure who all was involved in the development and modification of those engines. Johnny was; so was Dan Lutz and Les McBrayer -- but there may have been others. The basic powerplant was a Greenhead .09, modified with a proportional throttle.

For the early 1960's that was quite an achievement -- because the throttle was actuated by a rubber bellows connected via a long, thin plastic tube to a squeeze bulb held in the pilot's hand along with the handle...

(To those old geezers who remember it, this system was indeed like the one Jim Walker used for speed control on his "Walker Firecracker" .065 engines. In fact, most of the Greenhead's throttle system parts -- such as the bellows, squeeze bulb, and plastic tubing -- were stock Walker Firecracker items.)

...It's kind of a sobering thought to me, realizing that after Johnny's death, I'm the last survivor of that FAST seaplane project... Gosh it was fun ! And Johnny Brodbeck made it possible. [JW]

I was especially drawn to JW's comments regarding undercambered airfoils. I used them for many years in my own FF designs and particularly in R/C Assist Old Timers later on.

I might add that I have never been a "Contest Guy", and all of my FF experience has been with sport and sport scale models.

Now, since I have no formal aerodynamics training, everything I've done has been through trial and error, and the decision to either continue using, or abandon anything, was based purely on observation.

Over the years, I did notice a couple of things, and for that reason have basically abandoned the use of undercambered airfoils except in scale applications where those airfoils are necessary to retain a good scale appearance and performance.

The first thing I noticed was that undercambered airfoils don't penetrate well, unless the model is much heavier then I like to build. But at that point, the lift advantage was lost to weight.

In free flight, I found that in testing the same airplane using a typical "Clark Y" style airfoil verses the undercamber (at the same weight) flight durations weren't radically different (in dead air) -- but the altitudes reached and distance traveled were.

The Clark Y would climb much faster, and to greater heights, where the undercamber would just kind of float around. The real advantage to the Clark Y came from the higher altitudes reached, in that there was a much better chance of finding lift over 100 feet than there was under 50 feet.

Another great advantage was that flat-bottom airfoils are much easier to build and cover !

Now there is one undercambered airfoil that I am still using on the pre-1910 R/C designs that works really well. It's one that I came up with a few years ago, and is an offshoot of a flat-bottom airfoil that I experimented with in the mid 80's. The original airfoil was flat bottom, 12% thick, with a 40% high point, and a 25% LE radius. That's ultimately the one I used on most of my FF and R/C electric scale designs, simply because it worked so well.

It's very aft CG tolerant, and has a gentle stall at a fairly shallow angle of attack. It's happiest at wing loadings in the 6 - 10 oz range on wings with a chord of less then 7"; but was also used on a 12' span, 63 lb. UAV with a 24" chord with excellent results.

Lately, I've moved the high point up to 35% and reduced the leading edge radius to 17%, which works every bit as good, stalls at a higher angle of attack, but requires the CG to be moved up to about 30%.

The undercambered cousin to the early 40% high point design was reduced to 8% thick, and was undercambered from about 8% of the chord, back to about 70% chord, and the lower surface lifted toward the upper surface of the airfoil about 1.5% of the chord at about 30% of the relative distance.

I used this one on the Dare, 1909 Wright Military Flyer, after building a test wing for my original Farman 400 design, with the same planform to be used on the Flyer.

Now here's the interesting part. I flew the Farman first using its original wing until it hit the "Low Voltage Cut-Off", and recorded the time. I then flew it with the same battery, using the test wing, and the flight duration increased by almost 20%.

I repeated the test on two separate occasions and got basically the same results. The downside is that the airfoil has a vicious stall, which comes completely without warning, and requires a fair amount of room to recover. However, on canard designs, i.e. the Wright Flyer, it worked great, because the wing never stalls.

So far, it's the best airfoil I've found for slow, underpowered models of OLD airplanes, and delivers very scale-like flight performance in those applications. To be used on a typical sport model, no thanks -- the stall is just too "predictably unpredictable".

Generally speaking, I have found that working with scale models with chords less than 7", airfoils really don't mean all that much, as long as they're curved on top and flat on the bottom.

I personally don't use what some would consider "high performance" airfoils, simply because it's practically impossible to reproduce the shape accurately, and on an open structure, the airfoil is different at any given point on the wing anyway. But, for those who are building competitive models, or striving toward high speed, all that I have offered here becomes completely irrelevant.

The observations offered here are only pertinent if slow, relaxing sport flying is where your interest is. PAT

May I suggest a method to get the most out of "single surface" undercambered wings. Wing twist is avoided by using such wings in biplane or triplane configurations. In doing so, a truss type of structure results that is very rigid--indeed such wings as I have built along these lines are stronger than the rest of the airplane. That may be because I can get away with ribs and spars of birch (tongue depressors) and ash.

Both of these woods can be bent permanently by wetting in a microwave and dried in shape before assembly. (Tongue depressors are bent and used as flat ribs. Ash spars are the leading and trailing edges.)

These frames can be covered with common stationery Tyvek using ordinary aliphatic glue and is heat-shrunk after drying. Cut up large Tyvek mailing envelopes (available at any Staples for example).

Doping (if necessary for use with internal combustion engines) is done with water-based urethane. Works great for me. Now go make something beautiful! Tom Arcoleo

...Tom, I was guilty of gross oversimplification in my remarks about my own "single-surface" wings. The ones I've been using on small rubber-powered & CO2 free flights and 1/2A R/C models were sheet balsa, steam-formed (by a process I developed 30 years ago) to an accurate McBride B-7 airfoil. There are no ribs or spars involved; and on wings with chords of 6 inches and under, no warping problems have ever occurred.

But my 7-incher (on a monoplane) wasn't so satisfactory. [JW]

Am in the middle of constructing a 20" span 1940 STRUCK "New Ruler" and contemplating the building of the pylon area. I knew for sure that I would never be able to cover the pylon with tissue with acceptable results, so I used an 1/8" balsa core sandwiched by two pieces of foam.

I sanded the shape into the pylon, covered the fuselage and got it ready for paint. Zowie...I'd built myself into a corner. Can't use any kind of enamel as it will melt the foam.....can't use water- base as it will sag the tissue and not re-tighten. (Don't ask how I know this.)

* gave pylon two coats of 50/50 white glue & water. * covered with Japanese tissue. * two more coats of 50/50 white glue.

I made up some sample pieces of foam using the above procedures. Painted the first sample with two coats of 50/50 Sig Lite Cote. Painted the second sample with Krylon Enamel paint, right from the can. Neither procedure produced any damage to the samples.

I'm submitting this in hopes that it might help others who occasionally use foam in their structures.

A couple of months ago I asked if anyone on the list had built Early Models' Roaring 20 and Schoolboy with e-power.

Is there a web site for "Early Models" ? I'd appreciate an address if there is one.

Anyone out there know where I can get a set of full-size plans for Leon Shulman's Zombie? I'll trade a set of Henry Struck's New Ruler plans for it, or buy them. W. Zober

I have been getting SMALLnet for several years. I wonder: is there anyone who is interested in free flight compressed air powered aircraft ? Planes using motors such as the Bert Pond Whirlwind or others.

I realize the Pond planes were larger than SMALLnet deals with. I am interested in developing a small compressed air motor of about .020-.049 in size. Also, does anyone know who can repair a Brown CO2 motor ?

...Jim, compressed air power isn't widely popular, but there is some activity. Most of it today is done with the Air Hogs motor, from plastic ready-to-fly toy airplanes. Ken Johnson is quite an advocate of these clever little motors, and flies free flight models of his own design with them regularly, at the Balboa Park "Grassy Knoll" flying site in Los Angeles's San Fernando Valley.

Construction articles for two of Ken's C-A FF designs have appeared in Model Aviation magazine.

Speaking of Bert Pond: Bert continued flying C-A models powered by his 3-cylinder all-brass Whirlwind motors until he was well into his 90's. Bert was a friend of mine, and I built & flew a single-channel

R/C model powered by a Whirlwind -- had it in the air briefly at one of the early Little Rock SMALL meets. (The air supply hose from the tank to the motor kept coming loose.)

Bert also imported an Italian-made C-A motor. It was all-plastic, much like the later Air Hogs product; but far more adaptable to scratch-built models. That's because the motor was separate from its air supply tank. It also had an ingenious "air valve" design that delivered nearly constant motor performance until the pressure dropped to about 40 psig.

The main problem with this motor (called the Z-Motor, if I recall rightly) was its fragility. Bert and I and the late, great Doug McHard in England, all devised ways of beefing up the Z-Motor. Doug did the most thorough job, but mine could handle 165 psig air with no difficulty. (That's the "legal limit" for C-A models, established by SAM back when interest in "vintage C-A" free flight models was growing -- circa 1980.)

Last year I saw a beautiful all-metal home-made version of this motor at the Grassy Knoll site. Compressed air has many advantages (such as zero fuel cost !) and deserves to be more widely used. One possible further development that I intend to try is using big aluminum beer cans (available in 24-fl. oz. size in California) -- for the air tank.

Source: CO2, Brown CO2 Repairs and Parts

As for repairs to Brown CO2 motors, Otto Kuhni is THE MAN for that. I lost my address book in a theft-of-everything on my trip to California last year, but you can contact Otto through the Blacksheep club. One contact for that is Tony Naccarato, at Tony & Addie Hobby Lobby in Burbank -- (818) 842-5062.

(T & A Hobby Lobby is one of the last REAL hobby shops in Los Angeles County. Sad -- there used to be four thriving hobby shops in Burbank alone...) [JW]

ADVENTURES in 1/2A: In 1950 I bought a K&B Infant. I've always been a Scale Model nut, so picked up a California Fokker D7 kit, 3/4" scale. The model was over-powered with the Infant, and flew way too fast, but never achieved altitude over 25-30 feet. It flew in circles, which completely suited our SMALL flying fields in North Carolina at that time. The Infant NEVER gave any problems...

Sunday afternoons, we would arrive at a field, where I unloaded my Testor's 39 fuel, a pump, and a battery. Fueled the Infant, squirted a gush in the intake and exhaust openings, hooked up the battery, flipped the prop; disconnected battery, and launched..

I would have a flight in before most of the other guys got set up.. The original aluminum Infant prop never lasted over a few flights.. being bent to h*ll. After that, I always used wood props.

Got hours of fun from the Fokker, knocking a wing off here and there.. No problem.

Finally, during a windy day, it ran into a house, and the fuel- soaked firewall gave up. Removed my Infant, and sold the remains to one of my flying buddies. He sort of restored the front end, and kept flying.

Then, the Dakota Biplane came on the scene... With a Baby Spitfire.. It was Almost Scale.. Always flew well, 'til same thing happened with firewall...

Tried couple different firewalls and continued flying. My Dakota eventually disappeared somewhere in the very large trees near one of the fields. I never found a trace.

Built Frank Ehling's Curtiss Condor (an all-sheet-balsa twin- engined biplane bomber !), from July, 1950, MAN. It also was too small for the Infants.. But, the plans were full-size.

In the early days of 1/2A, few scale models came out full size in the magazines... I hated to mail order plans, or anything else, for that matter.. Back then, everyone operated on very little hobby money, and bought from local stores..

Great Fun, until many of the guys began spending their money on women, getting married, etc.... I ended up with a bunch of Infants, OK Cubs and other SMALL engines because of those changes..

Did Cox make a glow plug connector for the .010 and .020 like the slip-on one for the .049 ? I have the one for the .049, and would like a source for the smaller Cox engines. Alligator clips are a pain to use for this purpose.

...Dan, the .049 "Cox Clip" works for the .020 and .010 also. Look at the slot in the clip's "tongue". You'll see two pairs of circular "bites" on the slot: a small pair behind the larger one. These small "bites" are intended for clipping onto the center post of the .020 and .010 glow heads.

However, I've got to state here & now that the Cox glow plug clip is poorly made -- but can be modified to work far better.

First, cautiously slit the yellow plastic sleeve down one side. The plastic is tough and grainless, and it's all too easy for the knife to go askew when you try to make the cut at one slice. I recommend several passes that gradually go deeper.

When the slit's complete, spread it apart enough to remove the two beryllium copper "contact parts". Then with a small flat screwdriver, pry up the crimped "tubular" portions that hold the wires.

Throw those paltry wires away ! (Were you surprised to see that their insulation wasn't even stripped in the crimped area ? I was !) Use a length of lamp cord to replace the too-teeny wires that Cox provided.

Scrub the beryllium copper parts until they gleam, with a toothbrush and some aggressive kitchen cleanser (e.g. Ajax or Comet). Rinse them, then SOLDER the lampcord ends into the crimp "tubes".

Now reassemble the "Clip", using a length of shrink tubing over the yellow plastic to hold the unit back together.

It also helps a lot to keep the contact areas of the clip clean & free from oil coating and/or oxidation. And from time to time, spread apart the two contact parts, to make sure there's plenty of spring pressure of the "fork" part against the engine's head fins when the "split" part is engaged onto the glow head's center pin. [JW]

SMALLnet Posting post454