OOps! Typo. 1080 should be "1018". Sorry....
--Steve
On 3/29/19 5:32 PM, Steve Peterson (Redacted sender steve_peterson for
DMARC) wrote:
1080 (aka "CRS" -- cold rolled steel). But if you actually *like* machining stainless, go ahead :-)
A slightly more machinable alloy is "12L14" also known as "ledloy" which has a tiny amount of lead added to the steel to make it more machinable. I've used both and seen no difference in erosion or other wear.
--Steve
On 3/29/19 4:54 PM, William Schmiedlin wrote:
This is great news!
What alloy are people using? 300 series stainless steel?
Regards,
William Schmiedlin
On Wed, Mar 27, 2019, 10:45 AM Rick Maschek <dmarc-noreply@xxxxxxxxxxxxx <mailto:dmarc-noreply@xxxxxxxxxxxxx>> wrote:
Somehow I thought this had been announced here. Some of you may
already be aware.
This is a post by Steve Shannon, TRA President on the TRA forum
from last month:
/"At LDRS 36 in 2017, Rick Maschek requested the Board to
consider amending the Tripoli Research Safety Code to allow steel
nozzles for use with sugar motors used at Tripoli Research
Launches. At the time we requested that he provide data to our
Tripoli Research Committee Chair, Dr. Terry McCreary, to
demonstrate that the use of sugar motors would not increase risk.
The concern as I understand it is that the additional density of
steel would lead to increased momentum and thus greater range in
the event of a nozzle being spit. The counter to that is that
nozzles in properly flying rockets are spit downward rather than
horizontally. For static tests it's possible to require that they
be held vertically so the direction of a spit nozzle would be
vertical and thus have limited horizontal range. NFPA does not
prohibit steel nozzles.
Since that time Rick and Terry and I have discussed this
electronically several times, but we never did really receive data.
Honestly, most of us don't feel that steel nozzles necessarily
increase risk when used for sugar motors as long as all other
rules are followed.
So, rather than leaving this unresolved, Terry proposed that we
provisionally allow the use of steel nozzles with sugar motors
for both static burns and flights as long as the static burns are
vertical. The board voted on his proposal last week and it passed
easily.
The motion was for steel nozzle usage to be allowed for this
calendar year (2019). During that time we want Prefects and users
to come to this thread and relate any first hand accounts about
their use of steel nozzles, both good and bad, and especially
observations about spit nozzles. Of course for flights, an angled
blast deflector could redirect a spit nozzle, so observations
about that should also be made. At the end of 2019 Terry and the
board will review the data and make a determination whether to
incorporate that change permanently in the Tripoli Research
Safety Code. If we do nothing, this provisional permission to use
steel nozzles will expire at the end of 2019.
I should also point out that this is not mandatory. Local
Prefects have the latitude to ban the use of steel nozzles at
their home fields. Local Prefects always have the authority to
adopt policies that exceed NFPA and the Tripoli Safety Codes."/
Rick
