Medusa nozzle question

From what I can tell, Aerotech is doing away with the Medusa nozzle for the most part. But the 54mm J250FJ still uses one. I just picked up the reload, and noticed that only the center and two of the outer holes are open. The other outer holes are closed. Is this normal? I have emailed Aerotech, but sometimes it takes them a while to respond.

Yes, I have seen just one hole open as well as all seven. Depends on the load.

Yup, perfectly normal. The Medusa is kind of a universal blank, with holes opened for the appropriate loads. The J315 is the same way.

I believe that AT used the Medusa nozzle to cut costs. They can mold one nozzle, then, depending on the Kn requirements of the particular load, they can drill out one, two, or more holes. Eliminates the need to have multiple molds made. Not sure why it appears they are moving away from that, but I've noticed that lately, loads that used to come with a Medusa now use single throat nozzles.

cherokeej said:

I believe that AT used the Medusa nozzle to cut costs. They can mold one nozzle, then, depending on the Kn requirements of the particular load, they can drill out one, two, or more holes. Eliminates the need to have multiple molds made. Not sure why it appears they are moving away from that, but I've noticed that lately, loads that used to come with a Medusa now use single throat nozzles.

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Maybe it's just the 54/426 loads that are going from the Medusa to the smaller nozzle. It lists "original Medusa nozzle" and "new small nozzle" in the motor assembly drawings.

https://aerotech-rocketry.com/resources.aspx?id=6

qquake2k said:

Maybe it's just the 54/426 loads that are going from the Medusa to the smaller nozzle. It lists "original Medusa nozzle" and "new small nozzle" in the motor assembly drawings.

https://aerotech-rocketry.com/resources.aspx?id=6

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I think so - there is a special aft closure for that case as well.

chadrog said:

I think so - there is a special aft closure for that case as well.

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Yeah, I had to buy the smaller aft closure for a 54/426 I229T.

A professor at Mudd said that he had a Medusa nozzle that cracked between some of the throats... Maybe they're moving away from it to increase reliability?

Or maybe they just don't need it anymore now that they have all the molds that they need.

Cost factor.

Been a couple years, last time I checked the Medusa 54mm cost 14.95 vs the 38mm [which is why the newer small hole closure] for 1.50

They dropped the price of the soda can reloads also when they changed to reflect the cost savings.

You can buy all the components for all their loads separately at the RCS site.

blackjack2564 said:

Cost factor.

Been a couple years, last time I checked the Medusa 54mm cost 14.95 vs the 38mm [which is why the newer small hole closure] for 1.50

They dropped the price of the soda can reloads also when they changed to reflect the cost savings.

You can buy all the components for all their loads separately at the RCS site.

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The question is: why have they moved from Medusas to the larger, more costly 54mm single-throat nozzles?

Because according to Gary, and I asked him in person, the Medusa is substantially more costly than the smaller single throat nozzle that replaces it.


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Quake,,,
The bottom line is the nozzle is absolutely OK.........
They drill out a different amount of throats
to different diameters for different loads.............

Teddy

Guys, read what CJ said. The 54/426 is the only load going away from the Medusa( AFAIK). They are going with the 38mm blanks which are MUCH cheaper. Now I could be wrong about the Medusa, as I don't have the 426 but all the reloads in my stock I have that started out using Medusa still do. I looked in the bag.

H_Rocket said:

Because according to Gary, and I asked him in person, the Medusa is substantially more costly than the smaller single throat nozzle that replaces it.


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::blinks twice::

Was there something unclear about my question? The K1100 assembly diagram shows a Medusa nozzle, but nowadays they ship with the large, NOT the small, single throat nozzle. The one that is $27.50 on the RCS store as opposed to $18.70 for the Medusa nozzle.

See, thats why I put the disclaimer in, I don't know as much as I think I know. I have 2 K1100'a and I swear they have Medusas. Maybe not.

jimzcatz said:

See, thats why I put the disclaimer in, I don't know as much as I think I know. I have 2 K1100'a and I swear they have Medusas. Maybe not.

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Maybe it varies... I have seen one that definitely was single throat.

K1100T

old:
https://www.aerotech-rocketry.com/c...54mm_hp_rms/54-1706/54-1706_k1100t-m_assy.pdf
https://www.aerotech-rocketry.com/c...54mm_hp_rms/54-1706/54-1706_k1100t-s_assy.pdf

new:
https://www.aerotech-rocketry.com/c...54mm_hp_rms/54-1706/54-1706_k1100t-l_assy.pdf

note revision dates in upper right. Also there are a bunch of old motors floating in stock.

CarVac said:

Maybe it varies... I have seen one that definitely was single throat.

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K1100s had medusa nozzles for as long as I could remember. Then a K1100 I flew in 2006 had a single throat. I got all excited because that meant that I could use thermite in the K1100 I was going to fly in my Goblin for the ROCStock drag race. Then I got that K1100 in 2007 and it had a Medusa again. I lost the drag race.

Bottom line, I think it's whatever they have at the moment. The single throat 54mm didn't exist until the Medusas started having issues with the longer 54mm Redlines (K1275R especially, but a few of the K695Rs too), ask Bill Farr or Kurt about it sometime. My guess is that the mass flux through the individual tiny throats was too much for the phenolic, so they opened it up to a single throat, dropping the heat flow by a lot. Problem solved. And, bonus, now whatever's in the parts bin they can use.

ninja edit: DizWolf you just got a K1100T, yes? Are they single throat or medusa these days? I'm curious :cyclops:

ninja edit 2: When we flew Porthos at LDRS in Jean, K1100s had Medusa nozzles, too. But I got creative and built the thermite igniters into the motors at the pads, so they came right up when the ladder blew over, thus helping us find that mummified /thing/ out in the desert. See, the Medusas live up to their mythological naming, too!

daveyfire said:

ninja edit: DizWolf you just got a K1100T, yes? Are they single throat or medusa these days? I'm curious :cyclops:

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Haven't ordered one yet...just planning to. I've noticed stock age varies from vendor to vendor. Some of the overlap may be due to this.

https://www.aerotech-rocketry.com/resources.aspx?id=6

checking revision notes, they started swaping out medusas in 2002 in some loads, and more as years went on.