J180T

[rocketgroupmike]

Hi all, my PML Sudden Rush has kind of a short motor mount, and I was thinking the J180T would be perfect for my L2 attempt. The casing for this reload is the 54/852 and the 54/1280 will also fit my rocket. I'd normally go for the 1280, but I like the long burn... Are there any pro's or con's on this reload? Any comments on availability?

 

[solrules]

You can get the J135W for the 1280 case. It burns for about 7 seconds, and has just started to get back in production, so chances are you could get it from your local dealer. If not, Tim from Wildman Rocketry has it in stock. One fun motor!

EDIT: whoops, wrong name.

 

[rocketgroupmike]

Thanks Sol, but I'm not sure the J135 would lift my 5 pound bird. (J180 is borderline) I built it solid and added a payload section. Plus I just looked, and the J180 is 10 bucks cheaper...

 

[solrules]

Originally posted by rocketgroupmike
Thanks Sol, but I'm not sure the J135 would lift my 5 pound bird. (J180 is borderline)

Sure it would. According to Aerotech's graph...

The J135 produces an initial thrust of about 37 pounds. The initial thrust is the most important, as it determines if your rocket will get off the pad fast enough to get stable. Now, your rocket weighs 5 pounds, add in 2.5 for the motor itself, and you have a total of 7.5 pounds loaded rocket. 37 pounds/7.5 pounds = 4.9 thrust-to-weight ratio. A rocket will get up and stable on 3, with 5 being a pretty fast liftoff. People always tend to say never go under 5, and some even say none under 7, with no real need present. Sort of like overbuilding your rocket (which I am guilty of on occasion).

As far as the cost, that is you choice, but I prefer to .....live dangerously.....

have fun!!!

 

[Lacucaracha]

The J180T is a nice engine. It has more thrust early in the burn and will get your rocket off the pad faster than the J135 would.

I think it is a good choice.

Let us know how it goes...

 

[Austin]

I have about a 4lb rocket that would be perfect for the J135...I am going to have to try it some day.

Rocketgroupmike...the J180T is a great load, nice smooth takeoff with a long burn for a Blue Thunder. I would stick with it if that is what you want. While solrules makes some good points, the one that was forgotten was that you need to purchase a special extended forward closure to fly the long burn motors like the J135. If you have a standard 852ns casing, you probably only have the standard closure, so you will need to stay with the J180T.

Good luck and remember to post pics!

Carl

 

[gerbs4me]

sounds like a good choice motor for a L2 attempt

 

[rocketgroupmike]

Well, I don't own a 54mm casing yet, so whichever closure I need is no problem. And I do like the smoke... I guess I will think about it some more. Any other comments?

 

[Papa Elf]

Won't be able to do that at a CMASS launch... because I suspect it'll go over 3000 ft. However, if you are going to another launch, and like to borrow a case, let me know. I even have the extended closure if you need it .