Thanks Ken for the reply,
Apologies for my late reply as I was a bit busy yesterday but I wanted to ask
for you to maybe explain a bit more on the use of the regulator to purge as I
am struggling to understand how you suggested to use the regulator with the
check vales and two solenoids. Could you try and explain a bit more if possible
as I think due to my lack of experience is impeding me from understanding it.
I have looked into the Swagelok bored fittings on your advice for the dip tube
and it does look extremely interesting so I thank you for the suggestion.
Cheers again,
Elias
From: roxanna Mason<mailto:rocketmaster.ken@xxxxxxxxx>
Sent: 04 January 2021 18:43
To: arocket@xxxxxxxxxxxxx<mailto:arocket@xxxxxxxxxxxxx>
Subject: [AR] Re: Regarding Hybrid Rocket Feed System Design
A health purge will do wonders. Have a regulator set maybe 5-10% below your Pc
with a check valve and 2x sol. valve between the reg and your motor
When you fire the motor energize the 2x sol. valve. purge gas will not flow
against chamber pressure higher than the purge reg set point. At end of burn
once the motor Pc drops it hands off to the purge. You get an instant
transition from Pc to purge, works great.
Dip tube? We're having a similar requirement on our 1.5KLbF LOx/Kero rocket. I
proposed a swagelok fitting with the dip tube slid down to the desired liquid
level then swage the tube. If a level change is needed either cut the tube for
a higher level or change out to a new swage/tube assembly. You can also use
brass hardware store compression fittings for low budget easy access supply.
Not sure what your other question meant with a reg ball valve and nitrous but
be careful with the nitrous, don't let it cavitate or experience high
turbulence in a duct or get contaminated. Nitrous killed my friend and
colleague at Scaled Composites in 2010 along with two others.
Good luck,
Ken
On Mon, Jan 4, 2021 at 8:06 AM elias Aoubala
<eliaslina88@xxxxxxxxxxxxx<mailto:eliaslina88@xxxxxxxxxxxxx>> wrote:
Hey Guys,
A while back I started a thread here about initially designing my feed system
for a Hybrid Nitrous Oxide- HTPB engine. I think I’ve finally come to final
possible design and I wanted to post it here to get some opinions from others
on the design.
Overall I had a few questions I wanted to voice about the current design of the
feed system I have. Firstly My question is as to how do I prevent a backflow of
combustion flames through the injector line once it is shut off after ignition.
My first Idea was to implement another Flame back Arrestor and/or have flame
back arrestors on each line(main and ignitor)- however I think there might be
another solution which I am trying to figure out.
For the purge/fill vent (which I intend to use so I can use a dip tube on my
fill tank instead of gravity filling), I was initially thinking to put it at
the 4 way fitting above the tank which would simplify the tank design
significantly however I was thinking this would just lead to the liquid flow to
just exit thought the 4 way fitting to atmosphere instead of actually entering
the tank. Im not so sure about the design decision so I would love to here
thoughts about it.
Regarding the actual Dip tube for my fill tank- I’m getting my tank bought from
a third party and I wanted to know is their somewhat of a universal method of
building a dip-tube (or generally how do you build a dip tube for third party
tanks) and how do I do it (no experience with dip tube design).
Another point Id like to mention is the positioning of the actual back up
regulator, would I require anymore regulators for use between the actual
automated ball valves for Nitrous Oxide?
As you clearly can see from this post, I am still new to this so any
help/advice at all would be very much appreciated given how confusing this feed
system stuff can get and I really do appreciate the amount of help you guys
have given me already.
Many Thanks again,
Elias