The stock engine power was not enough
to lift the transom even with an
aluminum air dam, a lot of shaft angle, a
lifting prop, and a deep strut. It was back
to the drawing board.
Brian Buaas’ 29 cc modified Zenoah
was installed along with a new air dam
and sponson ride pads. More weight was
added to the left sponson tip. A total of
12 ounces of lead was added in the left
sponson directly opposite the engine as
well as 26 ounces in the left sponson tip.
So much for a light wood build.
Testing the day before the Northwest
Scale Championships in Washington
showed this wasn’t enough. The ride
pads were cracking from flexing of the
1/16 inch sponson bottom skin, and the
turn fin wasn’t strong enough.
Fortunately, I had some good friends
around. Brian, Kelly Groul and I retired
to Greg Roth’s shop for rebuilding. The
next morning we fixed the last few
problems and were finally able to run six
laps at race speed. We had the fastest gas
scale boat at the race.
The lesson is that old time, true scale
designs have too much lift for modern
power. Thunderboat designers
recognized this and changed the hull
designs from true scale. Mike’s frame
kits follow Roger Newton’s plans and
true scale hulls may need modifications,
especially with round nose boats. The
modifications we came up with worked
very well and can be used with other
similar hulls. The vibration and loads
these huge boats put on everything were
beyond my experience. I was very glad I
filled the front of the boat with foam
both for floatation and stiffness. I should
have used 1/8 inch thick sheet on the
sponson bottoms as well as the tunnel.
Bolting parts through the tunnel bottom
worked, however using wood screws did
not.
Continued on page 16
PROPWASH
April 2013
15
events that need sponsorships so please see the website or contact myself for details.
We have also been working with many great people from around the country on
things like judges stand ideas and unique trophies. I wanted to thank Lenny Blake for
offering up his racing system which will be perfect for this major event. I know those
in D19 can attest how great the system is.
Many good people in Colorado and Utah are putting in countless hours to ensure
we provide a great race venue and all will enjoy there time in Utah. The host hotel is
currently taking online reservations and filling up fast. We also just put up KOA
camping information for those that would like to camp which can be found under the
lodging tab on the nationals website.
Stay tuned because in the next
Propwash
I will include pictures of what we are
doing at the lake and other sneak peak things that are happening in Utah
.
2013 NAMBA Nationals Go Online!
By David Santistevan
2013 NAMBA Nationals Co-Contest Director
This year will be the first year that registration for the Nationals in Salt Lake City
will be done entirely online. Look for the link from the NAMBA home page to create
your registration and submit your payments. You will instantly receive an e-mail
confirmation of your registration.
For those of you not quite ready for this, we will be providing help to get you
registered. Just call David Santistevan at (303) 932-6250 or Joe Scarpino at
(303) 484-8661 in District 20 and they will do the online registration for you. You will
just need to mail your payment to Co– Contest Director Robert Holland to complete
your registration.
We are excited about hosting the Nationals in District 20 and we will see you in
Salt Lake City!
Scaling Up
By Lohring Miller
NAMBA Safety Chairman
The new gas scale class has been slowly developing in the Pacific Northwest.
Marty Shallenberger with the help of other scale racers proposed a 20% larger than 1/8
scale hull to fit gas engines under scale cowls. Several years were spent experimenting
with engine rules to get to the present set. Mike Luszcz laser cut frame kits based on
Roger Newton’s 1/8 scale plans were enlarged to gas scale size. This makes many
boats from vintage round nose designs to the latest turbine boats readily available for
scratch builders. Epoxy glass boats are also starting to be available.
I have one of the first Insane Thunderboats. It has been very successful, winning its
first regatta and running a second or two off the two lap record. I thought a similar gas
scale design should be easy to get to run as well. Therefore, I picked Mike’s Newton
106 plan frame kit to make the 6221 $Bill or Miss Eagle Electric. I thought this
dropped sponson design looked almost the same as my thunderboat. As a good
University of Oregon graduate, I picked the $Bill featuring a duck on the side. Mike
McKnight’s graphics for that boat confirmed the choice. Besides, it’s always fun to
take a nothing full size boat and win with its model.
Construction was straightforward for experienced scratch builders. The laser cut
frames fit together perfectly. I decided 1/8 inch thick tunnel bottom sheeting would be
better for a gas engine’s vibration, but used 1/16 inch thick sheet on the rest of the
boat. I built a cowl from plywood and foam sanded to shape and covered with glass
cloth and epoxy resin. The scale engine was the hardest part.
The boat balanced at the same point as my thunderboat and weighed four pounds
less. It should have been very fast. The first time out with a stock thunderboat engine
was a big disappointment. The tail dragged and even a little throttle blew the boat
over. Why was this happening? To start with, the scale boat had more curve in the
front of the tunnel.
The $Bill running with a stock engine