November 2023

Next Meeting

Friday December 29, 2023

 

Meeting Directions: CrossPiont Church

 

Click Any Photo to Enlarge



The weather is getting colder in Minnesota after the Thanksgiving Holiday.  This morning it was 15F (-10C) so many of us decided to wear jackets to the meeting. Typically, the Friday after the Thanksgiving Holiday is our lowest attendance.  We had 23 members and guests join us for presentations, discussions and plain old brainstorming.

The meeting room was fully engaged when President Cal Branton started the meeting at 7:00.

We hope you had a wonderful Thanksgiving!



John Baligrodzki’s ¼ Scale Kokusai KI-76 ‘Stella’

John is building the prototype unusual observation aircraft from Dave Andersen’s latest set of plans.  This KI-76 has several unique design attributes;

1.)  There is no balsa used in the construction of this model.  The fuselage is built up from light ply formers and spruce and basswood.  The (very large) horizontal stab is shaped from pink insulating foam and covered with light fiberglass and poly resin.  The wing ribs are hotwired from pink foam and mounted to spruce leading edge, spars, and trailing edges.

2.)  The horizontal stabilizer has a substantial span.  That if you  combined it with the overall fuselage length of 92” would make the model difficult to transport for most modelers.

Dave Andersen incorporated a removable tail structure in the design that allows the complete tail assembly to be simply removed to fit the airframe in most Minivans or SUV’s and even small trailers.

Specifications: Kokusai KI-76 “Stella” ¼ scale

Wingspan:

Wing Panel Length

Over-all Fuselage length:

Fuse length w/Tail Removed:

Recommended Power:

Estimated Weight:

 148" (3.76m)

 68" )1.73m)

 92" (2.24m)

 74" (1.9m)

 70cc to 100cc

 35-45lbs (16-20kg)

John will be using an EME 70 twin with an electric starter.

 

Jan Larsen’s Digital Weight & Balance System

Jan demonstrated his latest upgrade to his own design weight & balance system using electronic load cells for the Main Gear wheels & the Nose/Tail wheel.

Jan has added the feature of Bluetooth communications to handle larger aircraft (up to 150# capacity).

 

David Andersen, New Building Article

"Cutting Stringer Notches with

A Thickened Scroll Saw Blade"

Some giant scale airplanes have hundreds of stringer notches.  Cutting ¼” sq stringer notches in fuselage formers and wing ribs can be inaccurate and time consuming when done with a conventional scroll saw blade. The blade is very thin so each side must be cut separately, followed by two more cuts that curve into the rear edge of the notch, then a couple of more cuts to trim the rear edge while turning the wood before and during the later cuts.

The task can be more precise and faster if the scroll saw blade is wider.  With a 1/8” thick blade, one need only cut one side and then cut the other side.  Two quick straight parallel cuts are all that is needed.  And if the blade is exactly 1/8” wide only one cut is needed for a 1/8” x ¼” stringer.  Here’s how to make your own thicker scroll saw blade:

Cut three scroll blades into six two-inch long sections.  Glue these to the center section of an uncut scroll saw blade. Be sure that all the teeth point in the same direction. Use epoxy and clamp together while the glue sets. 

Measure first.  This method may vary slightly with different scroll saws.

TEAM Composite’s 45% Scale Me-163 Komet - Update

Jan Larsen has created a nose camera system that will be mounted in the #2 unit.  It is based on a DJI camera system that uses code similar the Futaba’ S-Bus structure.

Jan has designed/built a controller to drive the pan-tilt capabilities as well as return a live 4k video to the ground for FPV (passenger rides) and recordings.  The system has a solid range of 8 miles and the video through the goggles is amazingly sharp & clear.  He expects to report more on these features in the Spring 2024.

Ahmed El Bassal showed the forward section (from the trailing edge mount forward) of the #2 build of the 45% Me-163.

Based on the flight tests of the prototype and analysis, Ahmed has been able to optimize the structure to reduce materials in non-critical areas and beef up the wing mount.

The effort has reduced the weight of that section by 20%

This model is coming together faster and will be expected to fly in Spring 2024.

 

Jan Larsen’s Machine Gun Sound Generator, for his 1/3rd Scale Balsa USA Fokker D-VII

Jan surprised us with his breadboard design for his machine gun sound generator.  Most electronic sound generators have difficulty being heard over the flying model at a distance.  Jan suggests that an amplified speaker system is challenging to reach the amplitude and frequency required to simulate a firing machine gun to an observer on the ground.

Jan’s solution is to eliminate the electronic sound module, amplifiers, and bulky speakers for a simpler mechanism.  Rather than simulating the explosive firing of a charge, he is firing explosive charges of gas.  He originally tested the concept by using compressed air and propane fuel.  The sound was rather disappointing.  He then replaced the compressed air with compressed oxygen and fired the charge.  The result was a ‘report’ loud enough to get his wife to run downstairs to see what had exploded.

Being a dedicated modeler, Jan built the control system from a conventional CDI ignition module commanded from his own design controller.  The controller is fed from the tachometer sensor from the engine and is programmable to provide single shots, short bursts, or repeated bursts sounding like they are firing through an interrupter mechanism.

Jan’s firing chamber is machined from stainless steel and has a blast diverter to direct the expanding gases and flame to each side of the chamber.  The controller operates solenoid valves for the propane and oxygen sources as well as the spark ignition.

Jan says the proof of concept works, but there are a few bugs to work out before he mounts it into his 1/3rd scale Balsa USA Fokker D-VII.  After all, what could possibly go wrong? (LOL)

 

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Contacts

Cal Branton, President

CalvinBranton@gmail.com

 

Larry Sorenson, Treasurer

SledWorks2@gmail.com

 

Scott E. Anderson, Secretary

andersonscotte@hotmail.com

 

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MNBigBirds@Hotmail.com

 

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