10 year old AT SU motor still good?

[Electronhammer]

A friend of mine gave me his AT Arreaux which had sat for roughly 10 years with a SU F motor in it. Rocket was stored in a garage which was not climate controlled (ie was subjected to temps from -25F to 105F). This motor any good? I think I know the answer, but thought I would ask. Thank you.

[cwbullet]

Maybe, It maybe hard to light. You need to first see if it is still certified. If not, you might have to fly it on research days.

[JStitz]

Before you stick an ignitor up there ream it out and get the oxidized coating roughed up so the propellant can ignite and pressurize the motor.

[chadrog]

Which propellant is it?

[Electronhammer]

Which propellant is it?

F50-7W

[shreadvector]

W = White Lightning which is the propellant most prone to surface oxidation crust/crud.

If you have a small round or flat file and it can fit throught the nozzle and find the slot in the propellant, you should GENTLY file the surface to remove the crusty layer. Do not use anything sharp, like a drill bit, as anything that can cut into the grain may create an extra large burning surface that can make the motor overpressure and fail.

Then use a nice hot igniter, like a Copperhead with a long area covered in pyrogen or a dipped igniter with a long pyrogen head. The trick is to find a head with lots of pyrogen and that will still fit into the slot.

F50-7W

[VARocketflyer]

W = White Lightning which is the propellant most prone to surface oxidation crust/crud.

If you have a small round or flat file and it can fit throught the nozzle and find the slot in the propellant, you should GENTLY file the surface to remove the crusty layer. Do not use anything sharp, like a drill bit, as anything that can cut into the grain may create an extra large burning surface that can make the motor overpressure and fail.

Then use a nice hot igniter, like a Copperhead with a long area covered in pyrogen or a dipped igniter with a long pyrogen head. The trick is to find a head with lots of pyrogen and that will still fit into the slot.

I know that W indicates White Lightning, but I recall even old F50 SU motors being Blue Thunder propellant. I have seen several SU motors mis-labeled in the past and I wonder if this might be the case here.

Mark

[shreadvector]

I guess we need to ask what brand of motor it is, since Aerotech never made an F50-7W. They make F50-6T, etc.

[shreadvector]

I will bet that it is an F20-7W.

[Electronhammer]

I guess we need to ask what brand of motor it is, since Aerotech never made an F50-7W. They make F50-6T, etc.

I thought it was 7W, but it is 6W. Guess that 1 second makes all the difference. LOL

[jbuscaglia]

I guess we need to ask what brand of motor it is, since Aerotech never made an F50-7W. They make F50-6T, etc.

AeroTech did make a batch of F50s and G80s using their "Fast White Lightning" propellent. They were even certified in 1998.

[Electronhammer]

Here are a couple of pics of the F motor that is in question:

[VARocketflyer]

I remember the G80 FWL motors, but didn't know about them also coming in F50s. Guess I missed those. As I recall, Ross from Magnum used to run specials on those G80 FWLs once a year or so since they were just running them in batches at AT rather than being a standard production motor.

Mark

AeroTech did make a batch of F50s and G80s using their "Fast White Lightning" propellent. They were even certified in 1998.

[mwtoelle]

The production date on that motor is 25 Nov 1991. The motor might pretty hard to ignite. How does the propellant look from the nozzle end? On the Arreaux, I would use a F50-9 instead of a F50-6.

[5x7]

The production date on that motor is 11 Nov 1991. The motor might pretty hard to ignite. How does the propellant look from the nozzle end? On the Arreaux, I would use a F50-9 instead of a F50-6.

How do you decode the date code?

[mwtoelle]

Until late 1998, Aerotech used a hexadecimal (base 16) code to hide the production date.

5B465 (hex).
5B(hex) = 91 (decimal)
465(hex) = 1125 (decimal)

There are some cases where Aerotech made some errors in their math, so not all date codes can be completely decoded. There should be more information in the rec.models.rockets usenet archive.