AT L850 nozzle

Steven88

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Hello. It’s been several months since I reloaded my previous AT L850 motor but I was pretty sure it had the Medusa nozzle and now I put one together today and it has the single throat nozzle. Has AT recently changed that or is this a mistake and I have the wrong nozzle with my reload kit? Wanting to fly tomorrow morning
 

DabCat

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According to the assembly drawing on the RCS website, it shows that it uses a medusa nozzle with 5 of the nozzles open. 1656735839617.png
 

Ethan

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1 x .344" + 4 x .242" is equivalent to single .594" throat, which happens to be P/N 01780-1 (per the drop down box)
It's likely they have just swapped the medusa for the single throat version on the newer load, but you could verify.
 

Steven88

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Thank you. Yes this is what it looks like.
1 x .344" + 4 x .242" is equivalent to single .594" throat, which happens to be P/N 01780-1 (per the drop down box)
It's likely they have just swapped the medusa for the single throat version on the newer load, but you could verify.
 

Steve Shannon

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Hello. It’s been several months since I reloaded my previous AT L850 motor but I was pretty sure it had the Medusa nozzle and now I put one together today and it has the single throat nozzle. Has AT recently changed that or is this a mistake and I have the wrong nozzle with my reload kit? Wanting to fly tomorrow morning
What do the current instructions show in the parts list?
 

Steven88

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I have read and reread the instructions to make sure I loaded the motor correctly but I’m having a hard time getting the aft closer to thread on the last tiny little bit. I can still get my finger nail between it and the case. Is this normal?
 

tfish

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its not helping that Aerotech is having website issues..


Tony
 

tfish

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I have read and reread the instructions to make sure I loaded the motor correctly but I’m having a hard time getting the aft closer to thread on the last tiny little bit. I can still get my finger nail between it and the case. Is this normal?
The key point is that you are feeling the orings compress. The closures are not meant to seat all the way.

Tony
 

tfish

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is there a motor vendor of Tripoli TAP or any L3 person at the launch ask them to check out your issue.

if in doubt ..don't fly.

Tony
 

tfish

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recentlyy..last couple years Aerotech came out with a new 75mm nozzle..it fits the smaller Aerotech 75mm reloads. This allows them to use a single throat nozzle when being used cross compatisble with a CTI motor case.

Tony
 

StreuB1

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Call Tim at Wildmans (815) 638-3200 to see if he is in the shop. He might have the answer for you or could give Karl a quick ring on his cell to find out if you are in a time crunch.
 

firemanup

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There’s an open AT thread in the propulsion section that Aerotech replies to and answers questions regularly, may try asking there for an answer.

I’ve flown L850s and don’t remember any of them being Medusa nozzles.
 

mrwalsh85

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IF you're not flying today, I will try to check out the L850 I have in the shop...
 

mtnmanak

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I have a newer L850 on hand and it has a single throat nozzle. The assembly diagram (posted above in #3) is from 1999 (and hasn't been edited since). I was under the impression @AeroTech phased out all medusa nozzles except for one J motor in the 54mm class, so if you see a medusa now, it is probably an old motor. That is a good question to post in the Aerotech Open Thread.

As noted a number of times, the rear closure not seating all the way is not a problem. The forward closure not seating all the way is a big problem, so I always tighten down the forward closure first, then the rear closure as tight as I can get it.

PXL_20220702_195708312.jpg
 

Steven88

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Customer service still exists even in the week ends! I give Aerotech 5 stars!!!

Here is their reply:

We don’t usually reply on the weekends but I did want to let you know that this is the correct nozzle.

Happy flying.
Jenn



BTW guys I had a great flight. Thanks for all your help!!!
 

Steve Shannon

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I stumbled across the announcement just now and thought this would be a good place to include it:
News from the Tripoli Motor Testing Committee:

Subject: new nozzles for 3 AT Reload Kits

Aerotech has announced their intention to replace the ‘medusa’-style nozzles in three 75mm reload kits with single-throat phenolic nozzles. These single-throat nozzles are configured to give the same Kn as the previously used medusa arrangement. The motors involved are the K560W in the corresponding CTI case, the K1000T, and the L1150R, both in Aerotech cases. The TMT committee has reviewed in-house testing data and seen no significant difference in any performance metric and has extended TMT certification to reload kits incorporating the new nozzles.
These reload kits will be offered to the public with new instruction sheets.

Alan Whitmore, Chair, TMT
 
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