2-Stage HEI on 75mm CTI

Buddy Michaelson

Sponsor
TRF Sponsor
Joined
Nov 7, 2018
Messages
500
Reaction score
466
Location
8337 Penn Ave So
Curious from those who have successfully flown 75mm CTI motors using HEI to light the sustainer, and any tips/pictures of those that have successfully done it. Thanks!
 

CTom

Member
Joined
Dec 22, 2013
Messages
20
Reaction score
6
1. Fill one end of the smoke grain insulator with 1/8" of JB Weld. Let harden.
2. Drill a 7/64" hole in the forward closure as close as you can to the center.
3. Insert the insulator into the smoke grain well.
4. Use the hole in the forward closure as a guide to drill a7/64" hole thru the JB Weld.
5. Remove the insulator from the smoke grain well.
6. Thread 1 or 2 pyrodex pellets onto a lighter.
7. At 1/4" from the pyrodex pellets, separate about 3/4" of the lighter wires and strip the insulation from each of these sections.
8.Thread the lighter wire thru the insulator and the hole previously drilled in the JB Weld just up to the area of wire that was stripped.
9. Tack the lighter in place inside the insulator with 5 minute epoxy. Let harden.
10. Make sure the sections of stripped lighter wires are separated and not in contact with each other.
11. Pot with High Temp RTV Gasket maker up to 1/8" from the top of the insulator. Let set up.
12.Top off the remaining 1/8" of the insulator with JB Weld. Let harden.
13. Grease the insulator like you would a smoke grain.
14. Thread the lighter wire thru the hole in the forward closure well.
15. Insert the insulator into the smoke well and makes use the lighter wire aligns with the hole in the forward closure. Gently add traction to the wire as you insert the insulator.
16. Put a drop or 2 of 5 minute epoxy on the wire on the outside of the forward closure.
 

Attachments

  • 20221001_165453.jpg
    20221001_165453.jpg
    488.2 KB · Views: 1
  • 20221001_165502.jpg
    20221001_165502.jpg
    1.7 MB · Views: 0
  • 20221001_165525.jpg
    20221001_165525.jpg
    1.6 MB · Views: 0
  • 20221001_165736.jpg
    20221001_165736.jpg
    462.6 KB · Views: 0
  • 20221001_165743.jpg
    20221001_165743.jpg
    314.1 KB · Views: 0

Cameron Anderson

Well-Known Member
Joined
Sep 14, 2018
Messages
832
Reaction score
382
Location
Reno, NV
That's the purpose for splitting and stripping the wire? I assume to provide the smallest, least accessable path for flame and pressure to escape the case?
 

MClark

Well-Known Member
Joined
Jan 20, 2009
Messages
3,257
Reaction score
1,620
Location
Glendale, AZ
Wires stripped to prevent gas leak. Insulation melts at low temperature.

Motor would be considered research with this modification.
 

CTom

Member
Joined
Dec 22, 2013
Messages
20
Reaction score
6
Cameron,
I have used this method on 4"/3" MD L3150/M840 and O3400/M840, and a 3"/3" MD M2150/L395.
Using the same method on CTI Pro 38 for 1.5"/1.5" MD J530/J150 at AIRFest this past August.
A friend has had 2 successful flights on 2.25"/2.25" MD L935/K300. The interstage coupler is very unique for CTI Pro 54 motors.
Hoping to fly a 3"/3" MD M2245/M840 at BALLS in 2023.
Attached is a picture of the O3400/M840. Unfortunately, the nosecone was pushed into the airframe at 43K' doing Mach 3. Still reached 60K' and had full recovery. A valuable lesson learned.
Chris
 

Attachments

  • -storage-emulated-0-DCIM-Camera-DSC-6689.JPG
    -storage-emulated-0-DCIM-Camera-DSC-6689.JPG
    2.5 MB · Views: 1

plugger

Well-Known Member
Joined
Apr 30, 2009
Messages
720
Reaction score
386
Wires stripped to prevent gas leak. Insulation melts at low temperature.

Motor would be considered research with this modification.
is there any HEI system that would not be considered research?
 

CTom

Member
Joined
Dec 22, 2013
Messages
20
Reaction score
6
Hi Tony,
When I read the Tripoli Competition Event rules, it appears that by using this method using commercial motors, it would not qualify for either a commercial motor record (section 2.9), nor would it qualify as a research motor (section 8.0-2).
Am I understanding this correctly?
Chris
 
Top