Original NAR Motor Technical Report 1962-1963

[shockie]

Attached are the original NAR Technical Reports for the Model Rocket Motors that existed in the 1962-1963 timeframe. With Drawings and motor information. Using the Thrust Curve Tracker at Thrustcurve.org, these old motors can now be flown in historical and today's modern models.

These were given to me by John Rahkonen about 15 years ago.

 

[prfesser]

Wow! Very interesting.

According to these papers, all the early Estes motors used paper casings that were 0.406" i.d. The C.8-0 (back when lb-seconds were used instead of N-seconds) propellant filled the casing almost completely, so there was no room for a delay or ejection charge. No single- or upper-stage motors.

I grinned at the label of "Astronite-B" propellant (black powder) and "ceramic nozzle" (clay).

Sometime after that the 1/4A and 1/2A motors retained the old casings, while the A, B, and C casings were increased to the current 0.50" i.d., leaving more room for propellant as well as for delay and ejection charges. They may have gotten New England Paper Tube or maybe some other company to produce higher-strength, thinner wall casings for this. That made possible single- and upper-stage C motors.

I was quite surprised at the Coaster motors, with a 1 1/16" o.d. paper casing only 3/32" thick. Of course they were coreburning motors that didn't require quite as thick of a casing. Still, that's as thin as today's 18 mm BP motors.

Prodyne used a paper-phenolic casing with today's standard 29 mm (1 1/8") o.d. casing. Phenolic being quite a bit stronger than plain paper, the wall was only 1/16" thick. The publications indicate that the propellant was a composite type, but based on the motor design I doubt that it was APCP. Those of you who make motors will note the nozzle throat and the endburning design.

Best,
Terry

 

[aerostadt]

I had a few of those Coaster motors. Back then it seemed like you were on top of the model rocket world going into new territory with one of those.

 

[shockie]

Wow! Very interesting.

According to these papers, all the early Estes motors used paper casings that were 0.406" i.d. The C.8-0 (back when lb-seconds were used instead of N-seconds) propellant filled the casing almost completely, so there was no room for a delay or ejection charge. No single- or upper-stage motors.

I grinned at the label of "Astronite-B" propellant (black powder) and "ceramic nozzle" (clay).

Sometime after that the 1/4A and 1/2A motors retained the old casings, while the A, B, and C casings were increased to the current 0.50" i.d., leaving more room for propellant as well as for delay and ejection charges. They may have gotten New England Paper Tube or maybe some other company to produce higher-strength, thinner wall casings for this. That made possible single- and upper-stage C motors.

I was quite surprised at the Coaster motors, with a 1 1/16" o.d. paper casing only 3/32" thick. Of course they were coreburning motors that didn't require quite as thick of a casing. Still, that's as thin as today's 18 mm BP motors.

Prodyne used a paper-phenolic casing with today's standard 29 mm (1 1/8") o.d. casing. Phenolic being quite a bit stronger than plain paper, the wall was only 1/16" thick. The publications indicate that the propellant was a composite type, but based on the motor design I doubt that it was APCP. Those of you who make motors will note the nozzle throat and the endburning design.

Best,
Terry

Terry I have a question about the 3 Coaster thrust-time curves.

If we assume all 3 motors use the exact same BP propellant, what would cause the 3 very different T-T curves? Nozzle geometry? Depth and shape of the core?

 

[hobie1dog]

so back then a "c"motor was the biggest?

 

[prfesser]

Terry I have a question about the 3 Coaster thrust-time curves.

If we assume all 3 motors use the exact same BP propellant, what would cause the 3 very different T-T curves? Nozzle geometry? Depth and shape of the core?

If someone out there has those motors, maybe they could measure the diameter of the nozzle throat. I'd guess that they have the same depth of core but different diameters for the core and the throat. If all three were the same, then they may not use the exact same propellant. Estes uses commercial BP, but perhaps Coaster made their own propellant, varying the composition slightly for a faster or slower burn.

 

[shockie]

If someone out there has those motors, maybe they could measure the diameter of the nozzle throat. I'd guess that they have the same depth of core but different diameters for the core and the throat. If all three were the same, then they may not use the exact same propellant. Estes uses commercial BP, but perhaps Coaster made their own propellant, varying the composition slightly for a faster or slower burn.

Since I long ago established the fact that these original Coaster motors were originally BP pyrotechnic skyrocket motors, it's safe to assume the BP was a slow 60/30/10 mix. That's the traditional BP mixture for literally hundreds of years.

That doesn't preclude later versions having a faster mic or even a combination of the two as was pioneered by Reinhold Tiling.

The original Coasters from 1959 did not have a distinct delay or ejection charges. Later versions did. In fact Coaster Corp received a Cease and Desist letter from none other than Orv Carlisle himself for incorporating a delay/ejection charges in his motors. The letter of course by was ignored by Menford Sutton, owner of Coaster Corp.

 

[aerostadt]

The original Coasters from 1959 did not have a distinct delay or ejection charges. Later versions did. In fact Coaster Corp received a Cease and Desist letter from none other than Orv Carlisle himself for incorporating a delay/ejection charges in his motors. The letter of course by was ignored by Menford Sutton, owner of Coaster Corp.

And of course, by 1965 Centuri was selling something like the Coaster motor under a bright orange and black wrapper called something Min/Max. I remember I had a few of the Coaster motors with I think had a wimple pale green wrapper that looked like the wrapper was ready to fall off.

 

[prfesser]

Since I long ago established the fact that these original Coaster motors were originally BP pyrotechnic skyrocket motors, it's safe to assume the BP was a slow 60/30/10 mix. That's the traditional BP mixture for literally hundreds of years.

That doesn't preclude later versions having a faster mic or even a combination of the two as was pioneered by Reinhold Tiling.

The original Coasters from 1959 did not have a distinct delay or ejection charges. Later versions did. In fact Coaster Corp received a Cease and Desist letter from none other than Orv Carlisle himself for incorporating a delay/ejection charges in his motors. The letter of course by was ignored by Menford Sutton, owner of Coaster Corp.

I did not know that the Coaster motors were originally skyrockets. Certainly, that's the classic mix and probably a correct assumption. However, it is possible to use the same tooling for all motors and three different compositions. Directions for speeding/slowing a mix appeared well over a century ago, though I don't recall which book. Throat measurements of the three motors would be conclusive...but as I said, you're probably right.

My mentor told me of one semi-authority who recommended changing the composition...of an APCP motor when it CATOed. THAT would be foolish, as it's far easier to simply redesign the motor slightly.

Related to your last paragraph: somewhere I have a letter from Frank Kosdon to my mentor, telling him to cease and desist selling snap-ring research hardware, as it was Frank's invention, etc., etc. The letter ended with a request for my mentor to please forward the letter to another person known to vend such hardware, as Frank didn't want to have to retype the letter... But that was Frank.

 

[rocket_troy]

Related to your last paragraph: somewhere I have a letter from Frank Kosdon to my mentor, telling him to cease and desist selling snap-ring research hardware, as it was Frank's invention, etc., etc. The letter ended with a request for my mentor to please forward the letter to another person known to vend such hardware, as Frank didn't want to have to retype the letter... But that was Frank.

That's gold

TP

 

[shockie]

I did not know that the Coaster motors were originally skyrockets. Certainly, that's the classic mix and probably a correct assumption. However, it is possible to use the same tooling for all motors and three different compositions. Directions for speeding/slowing a mix appeared well over a century ago, though I don't recall which book. Throat measurements of the three motors would be conclusive...but as I said, you're probably right.

My mentor told me of one semi-authority who recommended changing the composition...of an APCP motor when it CATOed. THAT would be foolish, as it's far easier to simply redesign the motor slightly.

Related to your last paragraph: somewhere I have a letter from Frank Kosdon to my mentor, telling him to cease and desist selling snap-ring research hardware, as it was Frank's invention, etc., etc. The letter ended with a request for my mentor to please forward the letter to another person known to vend such hardware, as Frank didn't want to have to retype the letter... But that was Frank.

Menford Sutton told me that in a telephone conversation circa 2008 about the Coasters we're descended from Skyrockets.

 

[shockie]

And of course, by 1965 Centuri was selling something like the Coaster motor under a bright orange and black wrapper called something Min/Max. I remember I had a few of the Coaster motors with I think had a wimple pale green wrapper that looked like the wrapper was ready to fall off.

Yep. The Coasters became the Atlas/Hercules BP motors from Centuri, which became the MiniMax line. It's really too bad they didn't last very long but that was due to their relatively high cost compared to the ABC of the time and the shipping requirement that they be shipped by Railway Express which was expensive back then.

Plus they were being gang rammed like pyrotechnic skyrockets, and there was quality control issues. That was finally solved by using a single hydraulic press per motor.
I've read there are literally thousands sitting in a hole somewhere in the AZ desert.

 

[aerostadt]

I had a Coaster motor that was a first stage motor (it might have been the 40 pound thrust motor). It was about the 1966 time-frame. I put a second Coaster motor rocket on top of the first stage and launched it on the Lake Michigan shoreline in my hometown. I guess it got about 400 feet when the second stage fired. I never saw the second stage again.

 

[aerostadt]

There are a few things out there on the internet:

https://plans.rocketshoppe.com/pubs/Coaster/coaster-docs.pdf