Looks very good! What are you using? Sucrose? Also, where are you getting your KNO3?

Edward

Potassium Nitrate
Sorbitol
Iron Oxide

I mix small batches by gram weight.

http://www.skylighter.com/

Could never find any of this stuff in the Cheyenne area.
May be available in Colorado.

Skylighter has been very prompt with shipping and
quality seems great.

This compaired to other tests was a little lazy.

Are you using the 65/35 mixture? I found sorbitol much easier to work with than any other of the sugars. I bought my KNO3 from a supply house in Denver - it was .40 cents/lb in 50 lb bags in 2003. I found a place in Denver also that sold sorbitol in 50lb bags for $1.50/lb.

I might have to dig up some of my old notes and make a 75mm motor soon....just love that roar.

Edward

Yes. 65/35.

Some very good prices. If they are still around, let Me know.

Mike, that does seem to be a poor burn to me. The exhaust plume seems to be kind of week and inconsistent. I am still in work putting together a test stand and would love to see some actual numbers from some of these motors. I would love to play with some of the sugar motors but I still here lots of horror stories about consistency. I'm sure you made this motor just like your others but the photos / video of your other motors showed better performance. So what was the difference? Was the weather just more humid when you made this motor, or was it the phase of the moon?

If people want to test motors I'll be more than glad to bring my test stand - I can go up to 220 lbs and 2500 psi, at up to 50kHz. It would be nice to have a static test day.

Edward

Mike/Edward.
Jeremiah and I have a test stand too, but I don't know what the max it can test is. Maybe Jer will chime in on this. I'm trying to figure out a way to do tests in Broomfield on our Church's property - North of town. I have a partial berm built and was thinking about digging a bunker of sorts. Not sure what the rules would be though. Do you have any ideas? It's on 20 acres.

I also have a friend with 35 acres and no close neighbors up by Carter Lake. He's already given me permission to test there and has plenty of dirt piles to hide behind. We need to have a test day.... Well, Jer and I need to do some more mixing, we don't have any test straws made for burn rate & chamber pressures. Lots of grains though.
Greg

Very nice! I've built quite a test stands over the years and this one is my favorite, fires vertically for hybrids and was within 1% on the NAR data for my certs. I've also got a 5000lb one for those big motors...but that one is only set up for 6" motors. I have a place I test up here in Fort Collins - on some acreage w/o no crops and no people.

Edward

Probably My 'pinch' of Iron Oxide'...When I started making sugar
motors, the web site I used suggested a pinch of iron oxide to
a 65/35 mix.

How much is a pinch?

I have since read a couple places suggested putting about 1% iron oxide. by weight. That is a more precise measurement, and two to three times what My pinch is. I will not over do it in the future but will put somewhat
more in My batches.

The slow soft burn was probably due to that.

I will test one, I was going to fly, saturday and put the results up
that day.

1% does a very good job of accelerating the burn rate. I've found that you get a much more conistent propellant if you ball mill some KNO3 until it is very very fine, almost flour like. You then mix that 1/3 flour to 2/3 regular by weight and then add your sugar and iron oxide. You get a smoother burn and it is much more consistent.

I would not go above 1% - but I know that measuring just a gram can be hard. I used to mix my sorbitol and iron oxide in a premix and then mix that with my KNO3. I would measure out 990 grams of sorbitol and 10 grams iron oxide. Mix them in a ball mill for a couple days and you get a very nice uniform product. Then mix that with the potassium nitrate.

What internal geometry are you using? If I remember I used 1" PVC, a washer that had a 5/16 hole in the middle for a nozzle and then a 3/8" aluminum rod that was turned 5/16" on one end for a core. I used to make them about 5" long.

Edward

Mine is pretty much the same.

I use an arrow for the core.

You can get wind chime parts at 'Hobby Lobby' in many differant
sizes that work well also.

Mine is 1- 8" to 9" grain. poured into the PVC. if I was to go larger,
I would make individual grains making a three or four grain.

I have made a few grains. With the idea of putting them into a
premaid case (RMS / LMS)

I purchased some LMS kits to try making some 29mm motors.
Have not tried that yet.

Tried a new forward closure today. Took less work and was a little
less involved in construction.

NNOOOTTTT 😳

With the help of My friend Carl with a countdown, It faild
almost immediately.

Glad it was in a test stand and not in a vise or a rocket.

I will go back to a closure that has not failed.
More Gooder.

latest tests. Went perfect. Everything works right. They are ready
to put in a rocket someday.

Thank You Carl for the countdown and commentary.

http://s46.photobucket.com/albums/f131/mshinn2001/