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Wayco said:
I think it was a Bay Area Rocketry Cert special. Buy the motor get the casing, or buy the casing and get the motor....
Does anyone still do that?
Click to expand...
A couple of years ago, AMW was doing that for CTI casings, but you had to buy two loads that fit the case. I don't know if that deal is still on.
 
loopy said:
I remember the cert specials where you could buy the case and get the reload. Would be nice if those still existed!
My question was more about what the failure mode was...what caused it to fail?
Click to expand...
The case failed at the forward threads. The forward closure shows that it burned through at the same place.
Now, the forward seal disk was never found, and don't you know I looked for it, but the failure occurred around 800 ft. and the rocket was under thrust. The pressure release blew a 5" (standard not thin wall) fiberglass tube completely in half:
Jughead fincan and motor.jpg
The forward closure:
Casing and forward closure.jpg

Being the devils advocate, you could assume that since the seal disk is missing, the motor was assembled without it. Considering who built it is an old fart, and he has done some airhead stunts in the past, that is a possibility. I'm not gonna bore you with how many 75mm Aerotech loads I've built without a failure, or how many seal disks I have seen with a burn through at the lip, let's just stick with the facts.
The motor casing failed at the forward closure.
 
Wayco said:
The case failed at the forward threads. The forward closure shows that it burned through at the same place.
Now, the forward seal disk was never found, and don't you know I looked for it, but the failure occurred around 800 ft. and the rocket was under thrust. The pressure release blew a 5" (standard not thin wall) fiberglass tube completely in half:
View attachment 598803
The forward closure:
View attachment 598804

Being the devils advocate, you could assume that since the seal disk is missing, the motor was assembled without it. Considering who built it is an old fart, and he has done some airhead stunts in the past, that is a possibility. I'm not gonna bore you with how many 75mm Aerotech loads I've built without a failure, or how many seal disks I have seen with a burn through at the lip, let's just stick with the facts.
The motor casing failed at the forward closure.
Click to expand...
Gotcha. I was just curious since that's the motor I'm using for my L3 attempt this fall/winter.
 
rharshberger said:
Its an unusual failure the M1297W is a really good motor and probably more L3 certs have been done on it than any other, based on the number I see being used for cert attempts.
Click to expand...

I flew my L3 on the M1315, because I already had flown the L1120, which is pretty much the M1297, but with the Medusa nozzle. Still a great motor!
 
Random question, I was putting an I245G together in prep for tomorrow, and was a bit confused. I don't remember ever using a forward seal disc for the 360 case, but the reload came with a phenolic liner and the instructions clearly indicate using the seal disc (and it came with the seal disc o-ring). Online instructions from RCS show a forward insulator, no seal disc. I put it together, and everything fits and looks right (same as any other motor using the seal disc), I just want to make sure I am not missing something. Maybe this is new? The outside tube packing doesn't say the seal disc is needed like other reloads that need it.
 
rharshberger said:
Its an unusual failure the M1297W is a really good motor and probably more L3 certs have been done on it than any other, based on the number I see being used for cert attempts.
Click to expand...
That was what I thought, and why I went with the 1297 (and the fact that I haven’t used a white motor got a cert attempt yet…Lol). Thanks!
 
Zyzzyva1000 said:
Random question, I was putting an I245G together in prep for tomorrow, and was a bit confused. I don't remember ever using a forward seal disc for the 360 case, but the reload came with a phenolic liner and the instructions clearly indicate using the seal disc (and it came with the seal disc o-ring). Online instructions from RCS show a forward insulator, no seal disc. I put it together, and everything fits and looks right (same as any other motor using the seal disc), I just want to make sure I am not missing something. Maybe this is new? The outside tube packing doesn't say the seal disc is needed like other reloads that need it.
Click to expand...
I’ve haven’t seen any 360 loads with a seal disc yet, but if it comes with the thin oring and a phenolic liner that’s what it’s for.

I did notice the I357s started coming with phenolic liners a year or two ago, but they still had a phenolic insulator; no seal disc.
 
Which loads use a thin nozzle oring instead of a seal disc? I remember using one of this since. That nozzle oring was a PITA to install.
 
Zyzzyva1000 said:
Random question, I was putting an I245G together in prep for tomorrow, and was a bit confused. I don't remember ever using a forward seal disc for the 360 case, but the reload came with a phenolic liner and the instructions clearly indicate using the seal disc (and it came with the seal disc o-ring). Online instructions from RCS show a forward insulator, no seal disc. I put it together, and everything fits and looks right (same as any other motor using the seal disc), I just want to make sure I am not missing something. Maybe this is new? The outside tube packing doesn't say the seal disc is needed like other reloads that need it.
Click to expand...

Flew one today. Also went together fine and worked great.
 
jd2cylman said:
Which loads use a thin nozzle oring instead of a seal disc? I remember using one of this since. That nozzle oring was a PITA to install.
Click to expand...
54mm loads with the Medusa nozzle have the nozzle to liner oring. It can definitely be a pain sometimes.
 
Can the 38mm end burn forward closure be used with standard reloads? I understand it wouldn't be certified, but would it work?
 
I’m curious, would a small 3s LiPoly be too high a voltage for the internal electronics in this little thing (granted it would have to be pretty tiny to replace a 9V battery and fit internally and I don’t know if such a thing can be had)? It looked good in person at the WSMC. As if I needed another LPR launch controller….:D

added: I also see there are all kinds of “9V rechargeble“ batteries on Amazon….but I’d wonder if their protection circuits might not like the short burst of high current that a motor initiator (whether yours or Brand E’s) needs to do its thing. Just what I need, another little research project. :rolleyes::)
 
Last edited:
BEC said:
I’m curious, would a small 3s LiPoly be too high a voltage for the internal electronics in this little thing (granted it would have to be pretty tiny to replace a 9V battery and fit internally and I don’t know if such a thing can be had)? It looked good in person at the WSMC. As if I needed another LPR launch controller….:D

added: I also see there are all kinds of “9V rechargeble“ batteries on Amazon….but I’d wonder if their protection circuits might not like the short burst of high current that a motor initiator (whether yours or Brand E’s) needs to do its thing. Just what I need, another little research project. :rolleyes::)
Click to expand...
I honestly don't know, Bernard. The battery should be capable of pushing at least 5 amps through the leads.
 
AeroTech said:
I honestly don't know, Bernard. The battery should be capable of pushing at least 5 amps through the leads.
Click to expand...
Have to be careful with a lot of the Lithium "9V" as they have PTC's built in that will limit the current to a max 5 amps, its a good idea to check the techvdata sheet for a battery
 
Amazon Basics 9V alkaline have the best short circuit current at 7A, even better than the original Duracell at 5.5A (Duracell redesigned them to a stack of rectangular cells and denied it. Max current of these is 2.2A, the same as cheap brands.) For our use, low drain with occasional near shorts, you need the high current. Amazon make sure they say 6LR61 for the cylindrical cells. https://www.amazon.com/Amazon-Basic...9v+battery+amazon&qid=1693408136&rdc=1&sr=8-5
Old Duracell $5 Duracell Old 1.jpg
New Duracell $5 Duracell new 9V 1.jpg
Energizer Lithium $12 Energizer Li 2.jpg
Amazon Basics 24 for $39 Amazon 9V 3.jpg
 
One of the problems with 9v batteries is that what you test today, might be completely different tomorrow and there is no way to know unless you've got access to an x-ray machine or buy a bulk lot and open one up
 
All --

I am not ready to do a complete inventory the motors in my magazine yet but I am going thru my 18, 24 and 29 mm Model Rocket Motors so I can fly model rockets at a near-by farm from time to time with my granddaughters.

I've found several bags of Aerotech RMS 18/20 E27-4T motors that are no longer listed in the Open Rocket DataBase nor is the E27 at ThrustCirve.org.

I did find a thrust curve from Apr 2000 in the RASP.ENG file I used to distribute in the rec.models.rocket days but the thrust curve came with a 'preliminary' annotation.

The data is below my sig. This is the thrust curve from the RASP.ENG entry:

e27.jpg

Am I looking in the wrong place for the E27 ?

Was it reclassified and subsequently renamed ( maybe the D21-T ) ?

EDIT: oops ! The D21-T is a single use 18mm motor so that's not it !

The Propellant looks fine and I am going to fly them but before I add a CUSTOM Motor.ENG file to OR, is there a better way to go ?

Thanks

-- kjh

This is the data from rasp.eng:
Code: 
;E27 RMS - preliminary
; Thrust Curve Fixed by rasp-fix ( was 22.08 N-Sec @ 0.93 Sec )
;
;E27                       18   70    4-7-10   0.0101   0.031     ISP-BT
;
E27         18         70     4-7-10           0.0101   0.0310   A-TR
             0.022     37.301
             0.043     32.270
             0.194     28.744
             0.323     27.738
             0.538     24.203
             0.688     20.169
             0.860     10.084
             0.925      4.034
             1.000      0.000
;Total Impulse          21.52 (N-Sec)
;Avg Thrust             21.52 (N)
;Specific Imp          217.27 (Sec)
 
Last edited:
kjhambrick said:
All --

I am not ready to do a complete inventory the motors in my magazine yet but I am going thru my 18, 24 and 29 mm Model Rocket Motors so I can fly model rockets at a near-by farm from time to time with my granddaughters.

I've found several bags of Aerotech RMS 18/20 E27-4T motors that are no longer listed in the Open Rocket DataBase nor is the E27 at ThrustCirve.org.

I did find a thrust curve from Apr 2000 in the RASP.ENG file I used to distribute in the rec.models.rocket days but the thrust curve came with a 'preliminary' annotation.

The data is below my sig. This is the thrust curve from the RASP.ENG entry:

View attachment 601238

Am I looking in the wrong place for the E27 ?

Was it reclassified and subsequently renamed ( maybe the D21-T ) ?

EDIT: oops ! The D21-T is a single use 18mm motor so that's not it !

The Propellant looks fine and I am going to fly them but before I add a CUSTOM Motor.ENG file to OR, is there a better way to go ?

Thanks

-- kjh

This is the data from rasp.eng:
Code: 
;E27 RMS - preliminary
; Thrust Curve Fixed by rasp-fix ( was 22.08 N-Sec @ 0.93 Sec )
;
;E27                       18   70    4-7-10   0.0101   0.031     ISP-BT
;
E27         18         70     4-7-10           0.0101   0.0310   A-TR
             0.022     37.301
             0.043     32.270
             0.194     28.744
             0.323     27.738
             0.538     24.203
             0.688     20.169
             0.860     10.084
             0.925      4.034
             1.000      0.000
;Total Impulse          21.52 (N-Sec)
;Avg Thrust             21.52 (N)
;Specific Imp          217.27 (Sec)
Click to expand...
E27T was a full length grain for the case. Not the D24T which is a different reload.
 
RocketScientistAustralia said:
One of the problems with 9v batteries is that what you test today, might be completely different tomorrow and there is no way to know unless you've got access to an x-ray machine or buy a bulk lot and open one up
Click to expand...

X-Ray not required.

The batteries have an IEC & ANSI code on the case and on the packaging. The 6LR61 or the PC1604 code
will guarantee you a 9-volt battery with the (6) cylindrical cells and welded connections.

IMG_6835.JPG
IMG_6436.JPG IMG_6982.JPG
 

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