Aug 03, 2011, 06:56 PM
USA, TX, Friendswood
Joined Jul 2007
How To Make A Thrust Tube For Dummies
*******Take all measurements in millimeters*******
1) Measure the inside diameter of the fan shroud (housing)
2) Measure the outside diameter of the fan hub (motor mount)
3) Unzip FSA Calc.zip
4) Input the figures you measured from the fan shroud into FSA Calc
5) Write down on a piece of paper the 85% FSA calculation from the center column labled Exhaust Diameter (single outlet) This figure will be your exit diameter.
6) Google "Cone Layout" and download it. It's free for a limited time period. If you decide you want unlimited usage you will have to pay for it after the trial has expired.
7) Measure the distance from the fan to the end of the rear of the fuselage. This will be the approximate length of your thrust tube. Write this figure down on the same piece of paper you wrote the exit diameter.
8) Measure the outside diameter of the fan shroud. Also, write this figure down on the same piece of paper you wrote the other two figures; thrust tube length and exit diameter
9) You now have your dimensions for the thrust tube.
10) Input the three figures from the piece of paper into the Cone Layout program. Diameter 1, Diameter 2 and Lengthh. Change all figures for angles in Cone Layout to zero to create a straight cone. Left click on "file" and print. You now have a template for a thrust tube.
11) Measure the inside diameter of the fuselage exit tube. Write this figure down. You might as well write it on the same piece of paper that contains the other three figures
12) Make a thrust tube centering ring. With a mechanical drawing compass draw two concentric circles using the fuselage exit diameter and the thrust tube exit diameter on a piece of 3mm foam sheet.
13) Cut the outer circle from the foam sheet and then cut the inner circle from the disc. This donut will be the centering ring for your thrust tube
14) Cut the paper cone template from the sheet you printed and tape the ends together down it's length forming a cone
15) With the fan housing cover removed from the fuselage temporarily curl the thrust tube down it's length , being careful not to crease it, and insert it from the rear of the fuselage large diameter end first all the way to the fan assembly. Ideally, the end of the thrust tube will fit over the fan assembly OD. If you were lucky the thrust tube will fit over the fan assembly and extend slightly out of the back of the fuselage. If not add a few mm to Diameter 1 and the length inputs in Cone Layout and keep making adjustments until it fits over the fan and extends out the fuselage exit.
16) Once you have a suitable thrust tube that meets all the criteria you can either use the paper one or more preferably transfer the shape to a clear plastic sheet, like notebook dividers, anything light and rigid, and use it for the final product. Attach it to the fan housing with tape or *PVA glue ( Elmer's ) and use the donut made in step 14 to center the tube at the exit and glue it in place as well
If I've left anything out or have otherwise been unclear in any way, my apologies.
* I suggest the use of PVA glue as it's water soluble in case removal becomes necessary.
Last edited by giuseppi; Aug 03, 2011 at 10:00 PM.