Engine Size

[UrbanKnight]

I want to get my father some engines for his latest creation, but all I've been able to learn from conversations with him are that it is just a hair above the max liftoff weight for an Estes E12-4. It's a 3FNC about 5.5' tall with a 24x95 motor mount. I don't have the Rocksim file to run any sims, and I don't know anything about Aerotech engines. Anybody know what Aerotech engines would be comparable to an E12-4?

 

[mwtoelle]

An Aerotech E20-4, E30-4 or F32-4, should work.

 

[GDJ]

E15 or E30 has plenty of punch for many rockets. E15 for long burns, E30 for short punchy ones.

 

[GregGleason]

What is the launch weight (without motor)?

Greg

 

[JPVegh]

Look into an "RMS" reloadable motor casing. I have a 24/40 which will fit an Estes D motor mount and takes E18, E28, F12, F24, and F39 reloads.

Sounds like a great fathers day gift to
me!:smile:

 

[UrbanKnight]

Thanks guys. I think I'll surprise him with a few of mwtoelle's suggestions and let him decide what to use. I know he will build more rockets to use whatever is leftover anyway!

 

[shreadvector]

Thanks guys. I think I'll surprise him with a few of mwtoelle's suggestions and let him decide what to use. I know he will build more rockets to use whatever is leftover anyway!

I was offline all wekend so just providing a late response now....

Take a look at the data sheets on the NAR S&T website and you will see that the Aerotech E20 (or E15 as they are the exact same motors with different labels) has higher thrust and more total impulse, so they will do the trick. They are D12 sized, so you will use the orange spacer in Estes kits or simply use a 1 inch length of empty used D12 casing as a motor spacer.

https://www.nar.org/SandT/pdf/Aerotech/E20.pdf
https://www.nar.org/SandT/pdf/Aerotech/E15.pdf


For the E12 sized motors from Aerotech, the simplest is the F32. It has LOT more total impulse and average thrust than an E12.

https://www.nar.org/SandT/pdf/Aerotech/F32T.pdf

 

[UrbanKnight]

Thanks. I'm probably going to order them tomorrow. His birthday is in a couple of weeks, and you should see the engines in his rocket at an SCRA launch soon.

 

[shreadvector]

I bring bags full of the E15, E20 and F32 motors to all the launches. I bought a ton of them to support TARC teams who needed motors at the last minute. They are available to anyone who needs motors. Ditto for RMS in 18mm, 24mm and 29mm sizes.

Thanks. I'm probably going to order them tomorrow. His birthday is in a couple of weeks, and you should see the engines in his rocket at an SCRA launch soon.