HAM Radio Tower DesignTeam HAM (2), 324B, Summer 2013

Robert FutchBlake Hill

Ben CohodasNick Mowrey

Mohammad Molani

The Bugatti of HAM Radio Towers

Blue Steel 9000

● Design HAM Radio Tower with easy

access to antennas near ground level.

● $1500 cost

● 50 feet tall

● Transportable by normal methods

● Able to be assembled by only two men

● Must withstand 80 mph wind

● No maintenance for 20 years

Requirements

● Based on chosen motor○ Motor needed to raise tower weight in allotted time○ Chosen motor gives the transmitted load that the

gears need to be able lift● analyzed multiple gear ratios● decided on gear ratio of 6:1

○ pinion teeth = 16, Disk gear teeth = 96 teeth● Go through analysis and find all constant

values● Find gear bending stress/wear contact stress● Use stresses to find Safety factors

Gear Analysis

Shaft Analysis

● Radial and Tangential Forces

● Resultant Moments● Alternating and Mean

Stresses● Modified-Goodman for

infinite life● 2x 0.75 l & 0.75 D (in)● 1x 0.75 l & 4.0 (in)● AISI 4140 Steel

Tempered & Quenched

Bearing Analysis ● Analysing/Summing forces of

each shaft resulting from gears and cable etc.

● Choosing bearing style based on loading forces present on shafts.

● Calculate critical dynamics load, C10 value for each shaft.

● Shop for bearings based on largest C10 value fitting desired size dimensions.

● Confirm bearings spec’s for failure by static load capacity C0

C10: 1,125lbs

C0: 657 lbs

Weld Analysis1. Estimate Allowable Weld

Stress tau2. Select an appropriate

Weld EXX Type3. Find tau primary and tau

secondary4. Total Weld Stress is the

Vector Sum of both types of stresses

5. Find Safety using Allowable Weld Stress tau and Actual Weld Stress

EXX 90h = h/16

Wind Analysis

● Tower must withstand 80 mph wind with temperatures found in the lower 48 States

● Reynolds Number in Transition Region of Air● Bending Failure of Cylindrical Mast at 60 ● Guidewires Can Resist hurricane wind

<220mph

Buckling Analysis

P-critical= 8346 lb

6c= 6939.72 psi

F.S= 4.17985

d of T-average= .305122 psi

D-pin= .07312 in

Design OverviewErects in 93 seconds using a ¼ horsepower motor.

Conclusion● Telescope and Tilt provides the easiest access to

antennas

● Final budget was over maximum, but cost is justified by

high endurance and ease of use

● Fully extended tower reaches 50 feet tall

● Transportable by Semi, or can be further broken down

for transportation by 9 foot trailer.

● Able to be assembled by only two men

● Withstands 60 mph without guy-wires and higher winds

with optional wires to improve withstands of 220 mph

● No maintenance for 20 years

Opportunities for Improvement

● The mast was most likely over designed and could be made smaller and lighter with a different material using permanent guy-wires if guy-wires were not a problem.

● The price of the motor could be reduced with a more complicated gear box, however this would also introduce more locations of failure.