[AR] Re: hovering rocket vertical position control
- From: Ben Brockert <wikkit@xxxxxxxxx>
- To: "arocket@xxxxxxxxxxxxx" <arocket@xxxxxxxxxxxxx>
- Date: Tue, 17 Feb 2015 18:09:14 -0500
It was a Haskel, and I'm working with another one again now to run up
some tanks to ~5000 psi with nitrogen. (This year I had a part I
designed proof tested to 9000 psi, which is my new personal record.)
Air at 100 psi is a boring utility gas, air at 2500 psi is getting
into the realm of scary oxidizers. There's a lot of potential energy
in there and you need to be cleaning for oxidizer service or you'll
unleash the chemical energy too.
If you google nitrous pump you can get an air-powered booster that
will pump anything to 1500 psi for $800. Funnily enough they're
shipped with seal materials that aren't nitrous compatible.
I would absolutely do a ducted fan 'rocket' before doing a cold gas
rocket. The cold gas one requires many of the complexities of a liquid
rocket but flight time is terrible.
Ben
On Tue, Feb 17, 2015 at 5:18 PM, Jonathan Goff <jongoff@xxxxxxxxx> wrote:
> Yeah, we had one of the Haskel gas boosters. It looks like you can pick
> something up on ebay for ~$1500 or less.
>
> http://www.ebay.com/itm/Hydraulics-International30-30-Air-Driven-Gas-Booster-Paintball-Scuba-/371245373173?pt=LH_DefaultDomain_0&hash=item566ff2d6f5
>
> Looks like with that you could get up to 3500psi of air or more with a
> reasonable compressor feeding it.
>
> ~Jon
>
> On Tue, Feb 17, 2015 at 3:10 PM, Jonathan Goff <jongoff@xxxxxxxxx> wrote:
>>
>> I can't remember. I think we had an industrial one. Can't remember what
>> flow rate it was designed for.
>>
>> Jon
>>
>> On Feb 17, 2015 2:37 PM, "Lars Osborne" <lars.osborne@xxxxxxxxx> wrote:
>>>
>>> What kind of booster did you use at Masten?
>>>
>>> There are industrial pressure boosters, which are in the $3000 range,
>>> and I found a manually operated one for paintball, which is $700. I am
>>> wondering if there is a sweet spot for low flow rate boosters, but
>>> automatically reciprocating.
>>>
>>> Thanks,
>>> Lars Osborne
>>>
>>> On Tue, Feb 17, 2015 at 1:25 PM, Jonathan Goff <jongoff@xxxxxxxxx> wrote:
>>>>
>>>> George,
>>>>
>>>> If you're doing that, and want more than a few seconds of flight, you'll
>>>> likely need to go to higher pressures than a normal air compressor can go
>>>> to... But there are those differential piston gas pumps we used at Masten
>>>> to
>>>> take low pressure helium and boost it back up to enough pressure to refill
>>>> a
>>>> T-bottle.
>>>>
>>>> ~Jon
>>>>
>>>> On Tue, Feb 17, 2015 at 12:35 PM, George Herbert
>>>> <george.herbert@xxxxxxxxx> wrote:
>>>>>
>>>>> For (very) short flights, compressed air rockets using COTS tanks
>>>>> (like, standard propane bottles) give you more rocket-like behavior and
>>>>> are
>>>>> still darn cheap. Air compressor, tank, compressed air "throttle" valve,
>>>>> whatever thrust vector you want to employ.
>>>>>
>>>>> They even really are a rocket - it's just rare to see cold gas
>>>>> thrusters these days.
>>>>>
>>>>>
>>>>> George William Herbert
>>>>> Sent from my iPhone
>>>>>
>>>>> > On Feb 17, 2015, at 9:26 AM, Nate Vack <njvack@xxxxxxxxxxxxxxxx>
>>>>> > wrote:
>>>>> >
>>>>> >> On Mon, Feb 16, 2015 at 5:18 PM, <rsteinke@xxxxxxxxxxx> wrote:
>>>>> >>
>>>>> >> What have other people done? Are there other ideas?
>>>>> >
>>>>> > If you're looking to actually build a thing and test your stuff, you
>>>>> > might do well with model rotorcraft; IIRC, Paul Breed tested a lot
>>>>> > with helicopters. Quadrotors could reasonably approximate
>>>>> > multi-engine
>>>>> > rockets, and you could probably build a single ducted-fan design that
>>>>> > would hover, too.
>>>>> >
>>>>> > Moving to actual rocket hardware will still involve some surprises,
>>>>> > of
>>>>> > course. But crashing a $500 model is... cheaper than crashing a
>>>>> > rocket.
>>>>> >
>>>>> > -n
>>>>> >
>>>>>
>>>>
>>>
>
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