Aerotech J 460T L Reload questions

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JP Morgan

JP Morgan

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I picked up an older AT reload, the 54mm J460T long delay.
Looking at the nozzle it has 1 center hole and 3 others around that. There are
3 other holes that are Not drilled out and there's no mention in the instructions
for drilling them either.
*Do these 3 need to be drilled out?
*Is this nozzle what is called a Medusa?
*Can I trust this older reload motor? Date Stamp is 1998.
AT J460T L.jpgAerotech J 460T long delay.jpg
I got it thinking it might do for my Magnum 3 but have a look at the Open Rocket
simulation and tell me?
Magnum 3 J460T Simulation.png
Maybe I can fly the Magnum 3 with just the lower section, do a motor ejection...

I also need help in using the Open Rocket program to copy the Magnum 3 I've got
drawn up and pasting it so I can remove the upper tubing and Av bay section to run
a Simulation that way without drawing it all over again.

JP
 
I don't know about the reload, but my first thought is that if the instructions don't say anything about drilling the nozzle, then don't drill it. Only do what the instructions say and do everything the instructions say.

As for the Open Rocket, you should have a couple of choices. Use Save As to save the file under a different name and then modify that file. The other would be to use windows explorer to open the folder the file is in, make a copy there and then open the copy and modify that.
 
Yes, that is a medusa nozzle and it looks right to me. Leave it as. Age is not a concern, especially with BT propellant.

I would be totally fine with that motor in a Magnum, but not with the 14 second delay. I have a Magnum and have flown the heck out of it, and would think about 8 seconds would be just the right delay for this motor/rocket combo.
 
Handeman said:
I don't know about the reload, but my first thought is that if the instructions don't say anything about drilling the nozzle, then don't drill it. Only do what the instructions say and do everything the instructions say.

As for the Open Rocket, you should have a couple of choices. Use Save As to save the file under a different name and then modify that file. The other would be to use windows explorer to open the folder the file is in, make a copy there and then open the copy and modify that.
Click to expand...

Thanks. I'll try your suggestion for Open Rocket.
I'll burn the K550W first, then if the Open Rocket Sim works out for using just the lower half of the Magnum 3 I may
give the J460T a try.

I just wanted to check with you guys about the nozzle holes. Being a motor that's been around for a while I thought
maybe someone may have drilled the other 3 out and tried that with positive results...

JP

JP
 
J Blatz said:
Yes, that is a medusa nozzle and it looks right to me. Leave it as. Age is not a concern, especially with BT propellant.

I would be totally fine with that motor in a Magnum, but not with the 14 second delay. I have a Magnum and have flown the heck out of it, and would think about 8 seconds would be just the right delay for this motor/rocket combo.
Click to expand...

10-4.
I would be using dual deployment if the simulation run is on the numbers, meaning enough speed off the rail and such...
You say you have a Magnum but this one I have is the Magnum 3.
JP
 
DO NOT DRILL THEM OUT!
Years ago someone drilled out a J 275 and proceeded to fly it in a Bruiser.
It flew but, just barely.....


JD
 
JDcluster said:
DO NOT DRILL THEM OUT!
Years ago someone drilled out a J 275 and proceeded to fly it in a Bruiser.
It flew but, just barely.....


JD
Click to expand...

10-4.
I figured it would get the best of somebody and they would drill them out!
I suppose the other 3 holes would be removed for a 4/6 grain motor, this one being only 2 grains.

JP
 
I myself have flown a few J 275's.
If I remember correctly; the center core and 2 outer holes are used
Making it 3 in a straight line that are drilled out.


JD
 
That is correct, don't drill anything!!!

JP Morgan said:
I picked up an older AT reload, the 54mm J460T long delay.
Looking at the nozzle it has 1 center hole and 3 others around that. There are
3 other holes that are Not drilled out and there's no mention in the instructions
for drilling them either.
*Do these 3 need to be drilled out?
*Is this nozzle what is called a Medusa?
*Can I trust this older reload motor? Date Stamp is 1998.
View attachment 246592View attachment 246593
I got it thinking it might do for my Magnum 3 but have a look at the Open Rocket
simulation and tell me?
View attachment 246591
Maybe I can fly the Magnum 3 with just the lower section, do a motor ejection...

I also need help in using the Open Rocket program to copy the Magnum 3 I've got
drawn up and pasting it so I can remove the upper tubing and Av bay section to run
a Simulation that way without drawing it all over again.

JP
Click to expand...
 
Dont drill anything. thats the way it is supposed to be Ive flown may of them.
 
The reason for the Medusa nozzle is that the throat area is easily adjusted by drilling, or NOT drilling, some of the sub throats.

If you look at the reload assembly drawings from Aerotech's website, you will see if the Medusa nozzle is fully or partially drilled out.
 
Do not alter the wy it comes from the manufacturer, if you do you are effectually turning it in to a research motor under the rules.

As far as the propellent, I would use a little sandpaper and knock off the oxidation from the grain ends and cores, makes them easier to light.
 
JP Morgan said:
10-4.
I would be using dual deployment if the simulation run is on the numbers, meaning enough speed off the rail and such...
You say you have a Magnum but this one I have is the Magnum 3.
JP
Click to expand...

Understand, but there is barely any difference in weight between the Magnum and Magnum 3.

I personally would have no problem with flying my Magnum, payload section and all, with a J460.
 
If you would like to see a picture of my Magnum-3E coming off the pad at this years Midwest Power 12 on an Aerotech K535W. See Eric Cayemberg's Nov. 5,2014 post at Cheap & Dirty Random Pics regional launches on this forum. Dual Deploy to 3400'. Greg Olson
 
I almost did this on my first medusa. Thank to a club member for intervening!
 
I thought at first that maybe the 3 holes not opened up were like other single throats
that almost always need pushing out and cleaning up...

With help from you guys I was able to use Open Rocket and simulate a "short" Magnum 3.
Short Magnum 3 on J460T L.png
Looks promising, although I would rather use the full rocket and dual deployment.

So what are your thoughts on the "first" Simulation I've run using the J460T with the entire Magnum 3?
Is that enough speed off the rail, Enough Altitude for dual deployment with 2 altimeters?

JP
 
rdbones said:
Do not alter the wy it comes from the manufacturer, if you do you are effectually turning it in to a research motor under the rules.

As far as the propellent, I would use a little sandpaper and knock off the oxidation from the grain ends and cores, makes them easier to light.
Click to expand...

Shouldn't be necessary with Blue Thunder propellant. One thing that Blue Thunder loads have going for them is that they age well. I myself have used ones from the mid to late 90's. Absolutely no problems at all.

If it were White Lightning, than most definitely.
 
It appears that the Open Rocket model pictured has a tail cone on the Magnum. Unless I've completely and totally missed something since the early 90's, I'm unaware of tail cones on anything LOC with the rare exception of the Laser LOC series. Was this something you added or perhaps a LOC add-on? I've been looking for a LOC 5.45 to 4.00 transition; if you have a source let me know!!

Also, the simulation on a K-550 to just over 3000' seems really low to me.... That, or I need to really, really, re-calibrate my senses! This seems more like a J-415 altitude with a K-550 more like 4,000'+.
 
I fabricated the tail cone, details in my build thread, used Payloadbay to draw it up and print the template.
I put a tail cone on my LOC IV too. You could say they reduce drag and I think they make the rocket look
more like a rocket.

The Altitude should be correct. It weighs 19 pounds. It's built well!
If it goes a little higher that's okay. I'll go back and weigh it out again...

Thank you for the input.

JP
 
I found these photos of German WW2 rockets. They used a Medusa like setup. It all has to do with chamber pressures as to how many holes are open and how much they are drilled out.

images57JSZDGL.jpg

imagesBTWZ113W.jpg
 
JP,
The J 275 W has 3 drilled out around the center hole..
The Redline J 315 has 2 drilled out around the center so they are in a straight line....
The J 540 red also has 3 around the center....
Aerotech know's what they're packing with the load...

Don't change anything....

The age of the propellant make no difference....
The worst case is it can be harder to get lit....

Teddy
 
Last edited:
I've flown a J 460 in the older Magnum with a central 54 mm + two 29 mm outboards.
The rocket was lost ( due to faulty electronics) for 2 months then returned.

I flew a K 1100 a few years ago..... The motor was at least 10 years old.
Not trouble at all! I even went so far to retro fit the motor with the newer seal disc which the original never had.


JD
 
JP Morgan said:
I fabricated the tail cone, details in my build thread, used Payloadbay to draw it up and print the template.
I put a tail cone on my LOC IV too. You could say they reduce drag and I think they make the rocket look
more like a rocket.

The Altitude should be correct. It weighs 19 pounds. It's built well!
If it goes a little higher that's okay. I'll go back and weigh it out again...

Thank you for the input.

JP
Click to expand...

Wow, 19 pounds is a solid build so those altitudes seem reasonable. I'm digging up your build thread now.... Thanks for mentioning it.
 
pyrobob said:
Wow, 19 pounds is a solid build so those altitudes seem reasonable. I'm digging up your build thread now.... Thanks for mentioning it.
Click to expand...
Keep in mind that's 19 pounds all up weight/loaded.

JP
 
I looks like LOC is showing the stock Magnum-3 at 8.5 pounds dry. How about yours?
 
Many a year ago, I flew my extended Magnum (full tube instead of the half tube for the payload) on its first voyage on a J460T. Rocket had a fiberglassed coupler and an RRC2 in the altimeter bay, a 3rd centering ring, but was otherwise built stock. IIRC, the rocket flew to 1,650' and recovered perfectly under the Skyangle 52" Main.

14 year old me even wrote a review on Rocketreviews! https://www.rocketreviews.com/locprecision-magnum--by-dan-patell.html

3stoogesrocketry probably remembers it....2002 Invitational!
 

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