[sugpro] Re: Hello Sugpro
- From: "Andrej Vrbec" <dmarc-noreply@xxxxxxxxxxxxx> (Redacted sender "andre09091978@xxxxxxxxx" for DMARC)
- To: "sugpro@xxxxxxxxxxxxx" <sugpro@xxxxxxxxxxxxx>
- Date: Tue, 10 Feb 2015 21:30:01 +0000 (UTC)
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/ 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
>>
>> https://www.youtube.com/watch?v=z4QmCuDgi_w
>>
>> https://www.youtube.com/watch?v=zImHsYWY9-s
>>
>> 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
>>
>> https://www.youtube.com/watch?v=d_AweYPlwkk
>>
>> 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
>
>
>
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