[sugpro] Re: Hello Sugpro
- From: shawn.mchatten@xxxxxxxxxxx
- To: sugpro@xxxxxxxxxxxxx
- Date: Tue, 10 Feb 2015 18:01:55 -0500
Oh Man, oh man, oh MAN! It is SO good to hear someone talk science about
sugar again. I have missed this so much :).
Shawn
On 2015-02-10 16:30, Andrej Vrbec wrote:
> Ah, OK that makes it clearer. I thought that you have a 70cm BRB GPS version.
> No, I don't use any clamping. I know that clamping should improve density but
> I haven't yet come to try this. I typically get grains to about 97-97,5% of
> ideal density.
> I did quite some experimentation with different grades of potassium nitrate.
> My goal was to develop a mixing and casting technique that would allow me to
> use a fertilizer grade potassium nitrate which is very cheap and readily
> available. I've tried many different grades, particle sizes, pH values,
> defoamers, surfactants, vacuum degasing, you name it I've done it. In the end
> I just couldn't get the same high density propellant as I get when I use a
> food grade potassium nitrate without anticaking agent. I've read that a lot
> of people use fertilizer grade KN with good success but it wasn't working for
> me. Surfactans and defoamers helped to some degree but still the density was
> lower than with a food grade KN. It seems that anticaking agents used in this
> potassium nitrate fertilizers have a significant efect on wetting abilities
> of molten dextrose. as they make the KN particle surface more hydrofobic. All
> these problems went away when I switched back to a potassium nitrate without
anticaking agent, which is twice the price of fertilizer grade, but gives very
good results.
> So far I didn't have any problems with disbonding even in large grains. The
> material I use for the inhibitor is not a paper, but a gasket material called
> Tesnit BA-202, which is made of organic fibers and nitrile rubber. I cut the
> material to correct size to fit snugly in the steel tubular holder which is
> then heated in an oven to 150°C as well as base and a coring rod. Just before
> pouring, the mould is pulled from the oven and the propellant is cast. Here
> is the link to this material website: http://donit.eu/material/ba-202/ [1] I
> use 0,5mm thickness and the factory that makes it is conveniently located
> just a few kilometers from my home :)
>
> Andrej
>
> -------------------------
> FROM: Richard Nakka <richard.rocketry@xxxxxxxxx>
> TO: sugpro@xxxxxxxxxxxxx
> SENT: Tuesday, February 10, 2015 8:55 PM
> SUBJECT: [sugpro] Re: Hello Sugpro
>
> Andrej,
> Thanks for the info. I actually bought the new BRB900 unit, which
> comes with a simple GPS receiver. Great thing about this unit is that
> no amateur radio licence is required.
>
> To keep this post on-topic, here's a question about your propellant
> grains (beauties, by the way). Do you cure the KNDX under pressure or
> clamping? To prevent disbonding. I've temporarily migrated to KNSB to
> get good bonding (I use clamping pressure), but would like to get back
> to using KNDX...to hopefully get those nice flat thrust curves that
> your motors exhibit :-)
>
> Richard
>
> On Tue, Feb 10, 2015 at 1:06 PM, Andrej Vrbec
> <dmarc-noreply@xxxxxxxxxxxxx> wrote:
>> Hi Richard
>>
>> It's nice to hear from you again. You are right, the propellant is plain
>> KNDX. I've also experimented with other sugars (sorbitol, erythritol and
>> mannitol) but in the end I decided in favor of dextrose.
>> Bigredbee GPS was a real game changer at least for me as I don't have large
>> open spaces to fly from. I fly from a small clearing in the middle of the
>> dense forest and so far I haven't lost a rocket yet. BRB GPS is very easy to
>> set up. First you must download a configuration software from BRB website.
>> When you connect the GPS to the computer you can make settings like how
>> often do you want it to report location and altitude, your call sign, output
>> power, etc. On the ground you will need some kind of radio setup that can
>> decode incoming APRS data packets sent from BRB GPS. There are a lot of
>> options but mostly it comes down to how much are you willing to spend. Based
>> on my experience I would say that the best option for rocket use on the
>> field would be an all-in-one radio such as a Kenwood TH-D72 or a Yaesu
>> VX-8GR (recently discontinued) or Yaesu FT1DR. These radios are pricey but
>> very easy to carry around when you are chasing you rocket as you don't have
>> to have several pieces connected with cables as would be the case with an
>> ordinary radio connected to a TNC (terminal node controler such as Byonics
>> TinyTrak4) and a separate battery. When the radio receives the data packet
>> from BRB GPS it decodes it and displays a current altitude, latitude and
>> longitude. When the rocket lands you take the last known coordinates and
>> punch them into a handheld GPS receiver or if you have one of the above
>> mentioned radios it will display a distance and direction to the landing
>> site.
>>
>> Andrej
>> ________________________________
>> From: Richard Nakka <richard.rocketry@xxxxxxxxx>
>> To: sugpro@xxxxxxxxxxxxx
>> Sent: Tuesday, February 10, 2015 4:36 PM
>> Subject: [sugpro] Re: Hello Sugpro
>>
>> Amazing work, Andrej...! Your rockets are beautifully crafted.
>> Congratulations!
>> I particularly like your nice flat thrust curve, that's KNDX, right?
>>
>> GPS is a clearly a real boon to rocketry recovery, as your flights
>> demonstrate. I recently purchased a big red bee GPS and look forward
>> to flying it soon....although I must admit I haven't quite figured out
>> how to use it ...
>>
>> Richard
>>
>>
>>
>>
>>
>>
>> On Tue, Feb 10, 2015 at 3:16 AM, Andrej Vrbec
>> <dmarc-noreply@xxxxxxxxxxxxx> wrote:
>>>
>>> Hello guys
>>>
>>> I have just recently found out that Sugpro is active again. I really
>>> missed
>>> it, as it was always fun to read what others are doing with sugar
>>> propellants.
>>> Recently I have sucessfully flown a sugar rocket to 8km. Here are the
>>> videos
>>> of the motor static test and the flight:
>>>
>>> https://www.youtube.com/watch?v=Q2YJtmsqKSU [2]
>>>
>>> https://www.youtube.com/watch?v=z4QmCuDgi_w [3]
>>>
>>> https://www.youtube.com/watch?v=zImHsYWY9-s [4]
>>>
>>> Before that I also made a sucessfull flights with a 100mm M motor. You can
>>> see the videos here:
>>>
>>> https://www.youtube.com/watch?v=JJlIXvbbtNA [5]
>>>
>>> https://www.youtube.com/watch?v=d_AweYPlwkk [6]
>>>
>>> How many subscribers is there currently? I hope that most of the folks
>>> from
>>> the old Sugpro will join the new list.
>>>
>>> Best regards
>>> Andrej Vrbec
>>
>>
>>
Links:
------
[1] http://donit.eu/material/ba-202/
[2] https://www.youtube.com/watch?v=Q2YJtmsqKSU
[3] https://www.youtube.com/watch?v=z4QmCuDgi_w
[4] https://www.youtube.com/watch?v=zImHsYWY9-s
[5] https://www.youtube.com/watch?v=JJlIXvbbtNA
[6] https://www.youtube.com/watch?v=d_AweYPlwkk
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