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Author Topic: How to roll a “Tapered” balsa motor tube “Boom”  (Read 327 times)
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PantherM100
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« on: May 01, 2021, 01:04:01 PM »

Hi Guys:
I’m looking for a tutorial for rolling a Tapered balsa
Motor tube “Boom” for my P30 Motor Tube.
I realize that I will need a Tapered Mandrel. Are there
Any sources for the Mandrel blanks??  I considered
Tapered Golf club shaft blanks but they measured about
.600” tapered to .350”  Diameters.  Any other sources
That can be “Re-Purposed”??
Thanks advance for your help.
Sincerely,
Jon B. Shereshaw
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PeeTee
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« Reply #1 on: May 01, 2021, 01:18:38 PM »

A billiard or snooker cue will do the trick. Why do you need to make it tapered, as most P30 motor tubes are parallel?

Peter
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Tapio Linkosalo
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« Reply #2 on: May 01, 2021, 01:30:16 PM »


Or if you prefer tighter taper, take a wooden broom stick, and then plane and sand it to the taper you desire.
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PantherM100
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« Reply #3 on: May 01, 2021, 01:31:43 PM »

Peter:
I want the tail boom tapered to minimize
The weight at the tail.  Only the tube that is
Behind the motor Peg to be tapered. The functional
Part of the motor tube will be straight.
Sincerely,
Jon B. Shereshaw
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faif2d
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« Reply #4 on: May 01, 2021, 04:17:06 PM »

A tapered boom form can be made by using a metal bar or tube (.38 or what ever) and you then wrap a tapered brown paper piece of paper around the center tube.  It is hard to keep this tight enough but it is possible.
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gman
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« Reply #5 on: May 01, 2021, 04:55:10 PM »

Jon, For a tapered former as short as the "boom" on a P30 it's difficult to find anything with a steep enough taper (pool cues etc are too shallow). I made mine by rolling a cone in brown wrapping paper to the desired shape (over-long of course) and filling it with "Polyfiller" or any water based plaster type filler. I incorporated a spruce stick of, maybe, 1/4" square to give it some strength. Give it a couple of days to dry out and then tidy it up and wrap it in waterproof tape.   Mine's made three booms to date and still seems ok.

The weight saving over just having a parallel tube full length is pretty minimal if you consider the slender triangle of balsa which is removed, but they do look nicer I agree.

Gavin

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PeeTee
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« Reply #6 on: May 02, 2021, 06:23:53 AM »

Jon
My apologies, I thought you were looking for something longer. The method suggested by Gavin will give you a short tapered boom you are looking for.

Peter
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calgoddard
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« Reply #7 on: May 02, 2021, 09:27:53 AM »

I have built P30s with a straight rolled fuselage that extends the entire length of the model (except for the prop) and other P-30s with a rolled tapered tail boom.

The weight savings from using a tapered tail boom is minimal but a P-30 of that configuration looks good, as others have pointed out.  Bear in mind that it will be tricky to align a tapered tail boom with a straight fuselage section. If they both share the same central axis, you will need a larger stab platform to get the usual negative incidence on the stab. That pretty much negates any weight savings from using a tapered tail boom.

If you want to fly with a thinner P-30 rubber motor other than the typical 6 x 1/8 you will need extra length between the prop hook and the motor peg. Use of a 6 x 3/32 rubber motor, for example, in a P-30 model pretty much eliminates the use of a tapered tail boom unless the model uses a spring tensioner..

Stan Buddenbohm's Air Shark P-30 and Don DeLoach's Polecat MK 10 P-30 both have straight rolled balsa wood fuselages that extend all the way back beneath the stab. These fliers are almost unbeatable in P-30 competition in the United States.

As I recall, Bob White's twin fin P-30 has a long, continuously tapered fuselage made of rolled balsa wood.  The fuselage gets quite narrow around the motor peg, so it is difficult (if not impossible) to get a blast tube to couple onto the motor peg. He was also a formidable competitor.

I hope this input helps.
« Last Edit: May 02, 2021, 09:41:06 AM by calgoddard » Logged
danberry
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« Reply #8 on: May 02, 2021, 02:08:30 PM »

Get a dowel that matches the small diameter that you want.
Get some heavy paper. Cut a strip of the paper about two feet long- this will be more than long enough for your purpose.
Wrap the strip around the dowel until the desired diameter is achieved. Cut it there and discard the extra.
You are going to cut a triangle of pare that you will wrap around the dowel. You know how long yo want the boom so that is one leg of the triangle. The other leg is the length of your test strip. Wrap the paper triangle around the doel and secure the ends with glue or tape.
Wrap it with wetted balsa and proceed .
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atesus
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« Reply #9 on: May 03, 2021, 02:49:01 AM »

I roll the portion aft of the motor peg out of 1/32" balsa, no taper. 
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