Quantcast

Alternate methods of motor retention for 18/24 mm

The Rocketry Forum

Help Support The Rocketry Forum:

ScrapDaddy

Well-Known Member
Joined
Jan 26, 2010
Messages
2,081
Reaction score
1
For 18mm and 24mm motors, as far as i know there are Engine hooks/clips,
tape, friction fitting, and an extra bonus to 24mm there are madcow retainers
are there any other ones? besides the methods found in apogee newsletter **** which i already looked at.
 

Evo666

Well-Known Member
Joined
Sep 28, 2009
Messages
413
Reaction score
0
I'm going to try the tape method as suggested by Apogee. I've never used reloads before so got to find how to put one together. I'm also interested in other ways for motor retention since one of my hooks on my patriot went flemsy on me.
 

ScrapDaddy

Well-Known Member
Joined
Jan 26, 2010
Messages
2,081
Reaction score
1
I am just planning on buying a really nice scale rocket but i dont want an engine hook to ruin it all its a 24mm
 

Gillard

Well-Known Member
Joined
Jan 18, 2009
Messages
1,970
Reaction score
1
rowes retainers, really nice retainers, any pretty much the only thing that the UK has to offer to the rocketry world
 

MarkII

Well-Known Member
Joined
Jan 18, 2009
Messages
8,212
Reaction score
9
I haven't tried to construct one yet, but I'm sure that it is possible to make a motor clip for 18mm and 24mm that can be retracted back up into the mount for display purposes. Instead of a hook at the top, the clip would have a small flange that fits into a simple track. When the clip is fully extended, the flanged end is at the bottom of the track and is prevented from being pulled out any further and the clip then works like a conventional motor clip. The clip cannot retract once a motor is installed, because the thrust ring or the motor block prevent the motor from moving. Since the motor cannot move, the clip cannot move. Once the motor is removed, the clip is then free to slide up into its track and be out of sight.

QModeling has a retractable clip arrangement in its kits.

Mark K.
 

Trident

Retired, plenty of kits
Joined
Jan 18, 2009
Messages
859
Reaction score
9
Here is my suggestion. This was done for a cluster on a cloned Astron Cobra (I wanted it to look like the original -- no hooks), but could be done for a single motor. The threaded shaft holds a bolt (4-40 in this case). When motors are installed, a small washer is placed on the bolt, and holds in motors. When on display, the bolt is left out, showing no unsightly hook.



 

MarkII

Well-Known Member
Joined
Jan 18, 2009
Messages
8,212
Reaction score
9
Lee, that is identical to the method that I used for my Cobra. I did describe it somewhere recently, but apparently not in this thread. In any event, great minds think alike!

In mine, I attached a 4-40 blind nut to the forward end of the clustered motor tubes, and then secured it further with bits of epoxy putty around the edges. Since the nut is all the way at the opposite end of the cluster, I needed to use a very long (for #4 size) machine screw or bolt. I couldn't find any that were at least 3.25" long, so I used a length of threaded rod. I soldered an acorn nut and a #4 fender washer onto one end of the rod, and that is my bolt.

Mark K.

DSCF1144.jpg


DSCF1137.jpg
 

Trident

Retired, plenty of kits
Joined
Jan 18, 2009
Messages
859
Reaction score
9
Mark,

There were rumors that I had a twin brother, but we were separated at birth ...
;)

The 4-40 "threaded insert" I used is actually a control rod clip (clevis?) from the RC airplane world. It is the device to hold the threaded push rods to servos. I clipped off the "arms" that snap into the horn on the servo, leaving a very small diameter threaded tube that could drop down between the tightly spaced BT-20s.

Also, note the little can of Testor's red paint next to the Cobra. Once I started spraying, the paint gushed out around the nozzle, completely emptying the can. It was a hot day, so I managed to get several coats onto the fins all in the same spraying cycle. This is an excellent example of why I wear disposable nitrile gloves when painting!
 
Last edited:

Latest posts

Top