Philip with his first Carl Goldberg Li'l Jumpin' Bean, in our back
yard in Smithsburg, Maryland c1991.
A pair of plans-built, framed-up Li'l Jumpin' Beans ready for finishing.
Parts were all cut and prepared for both models prior to assembly,
so it was more like assembling prefabricated kits.
Milling a channel in the leading edges for the ribs.
Depth gauge clamped onto razor saw when cutting rib slots in leading
2 sets of wingtip balsa laminations.
Using electronics perf board as a drilling template for the elevator
Letting out the lines for Li'l Jumpin' Bean #2.
My son, Philip. learned how to fly a control line
airplane using the Carl Goldberg Li'l Jumpin' Bean. He is shown in the picture to the
right in our backyard in Smithsburg, Maryland, sometime around 1991. Philip was about
5 years old at the time. Note the use of ear protection.
The entire airplane was covered with Monokote for strength and ease of repair during
the learning process. A Cox Black Widow .049 engine provided power
Update, 25 years later: (June 10, 2017)
Having never been truly satisfied with the silence of electric-powered model airplanes,
I made a decision to start reverting back to glow fuel models. Yes, electric power is
clean, easy to set up, and consistent motor runs are the rule, but I grew up with models
I could hear flying as well as see flying. I've really missed the sound and smell of glow
fuel engines after a 15-year hiatus. I'm starting with .049 engines mainly because of
the high cost of fuel, but there's also a back-to-basics feel about them since I, like
most kids in the 1960s and 70s, learned to fly with the plastic Cox models.
As you might know, Cox model airplane engines were on the verge of disappearing from
the face of the Earth, and the main venue for acquiring them was eBay. However, thanks
to an enthusiastic Canadian lover of all things Cox, an enormous stash of Cox engines
and parts were salvaged from the Cox warehouse in Colorado and a new company,
Cox International, was formed to
assure the continued supply of engines and replacement parts. But, I digress...
Carl Goldberg plans for the Li'l Jumpin' Bean did not include full-size outlines of
the ribs, tail feathers, fuselage, etc., but fortunately some kind soul made a plan sheet
with all the individual parts. It can be downloaded for free from the
website. I used it to produce two complete 'kits' of parts. Wanting my Li'l Jumpin Beans
to be as authentic as possible, I took the trouble to reproduce all the components faithfully.
Yes, I know kits can be purchased from
Brodak now), but my guess is the leading edge does not have the groove
or notches for the ribs. Also, the Brodak version has a cutout in the fuselage for their
beam mounted .049 engine rather than the bulkhead mounted Cox engines.
Two Cox Stunt-Bee .049 engines were purchased from Cox International, along with two
mufflers. It seemed to me the engines were not running reliably with the mufflers, so
I removed one entirely and in the other drilled a second hole opposite of the factory
hole. That second hole did the trick and still made a big difference in the noise level
compared to the engine with no muffler. The other muffler was modified and now both run
great. I broke in both engines with 6-7 full tanks of 25% nitro fuel, and that's what
I've been flying with. I learned a long time ago that going to a lower nitro level on
1/4A and 1/2A engines means certain headaches with adjustments and keeping them running
for a full tank. A Sullivan 1/2A electric starter is used to get them going. About a cumulative
year of my boyhood was spent winding the spring starters in attempts to get .010, .020,
and .049 engines running, so at age 58, there's just no time to waste ;-)
This is the maiden flight of my plans-built Li'l Jumpin' Bean (Carl Goldberg design).
The Cox .049 Stunt Bee engine was bought from the Canadian company that bought out the
Cox engine line. 25% nitro fuel is used for this flight, as it was for 6 full tank runs
during break-in. A muffler is being used with a second hole having been drilled across
from the factory hole; this makes the engine run a bit more consistently, and is only
slightly louder. The control line length is 35', but they have been shortened to 26' in
order to reduce weight and drag. Thanks for watching. - Kirt Blattenberger
Melanie holding Li'l Jumpin' Bean #1 and #2. She has been my model airplane enabler
for almost 35 years.
... continued from above.
As I recall, the learning process went quite well,
with only a couple minor mishaps. The propeller was installed backwards to provide less
thrust, and the Cox Black Widow .049 engine was adjusted to run as slowly as possible
while still being reliable. By this time, I had finally purchased an electric starter
for small engines, so the process was much easier.
A few years later, we built two more Carl Goldberg Li'l Jumpin' Beans to use for dog
fighting. That was in Colorado Springs sometime around 1998. I've got picture somewhere
but cannot find them.