Static Test of 1st 3# motor

[billofca]

I had to leave on a business trip to Florida last Wednesday, and am just getting back to posting again now that I'm back home. I left off writing questions about nozzles last Tuesday, Nov. 2nd.

 

Yesterday I ball milled my first batch of BP rocket fuel (60-30-10). I had previously ball milled the KNO3 alone for 6 hours into a fine powder. Then I mixed the recipe yesterday and ball milled for 3 hours, using airfloat C. I then hydraulically pressed my first 3# motor using 2 teaspoons of fuel in each charge increment, pressing at 5200 psi (using the Wolter direct read gauge pad. I had only made 100 grams in the first fuel batch and used it all in building this first motor. The top tip of the spindle was still visible, so I finished it with a clay plug (about 3 heaping teaspoons) in one press increment at 2,000 psi.

 

Today, I dug a small hole in the ground and placed half the motor length in the hole (nozzle up) and packed dirt around the outside for the static test. It ignited into a nice roar and burned for about a second to a second and a half. No CATO, and no chuff, just a clean burn. The exhaust smoke shot instantly to maybe 40 or 50 feet straight up. There was no erosion to the nozzle (straight bentonite clay, pressed at 4.000 psi.) All in all, it was a perfect test. Visually, it looked and sounded like a very powerful thrust. Not bad for my very first rocket motor. I have a 300 gram of the same fuel recipe in the ball mill now for about 2 hours. On to building more motors and attaching a balancing stick for a first flight. I just finished reading a thread of previous posts on rocket stabilization (sticks and balancing, etc.). You guys are great at sharing your knowledge.

 

Tomorrow I will go to Home Depot to get a Royobi bench top table saw for cutting the sticks. Anyone have experience with this table saw, pro or con?

[Fly]

I hope that motor did not rock the earth off its normal orbit!

 

Fly

[billofca]

I hope that motor did not rock the earth off its normal orbit!

 

Fly

 

Nope, but it did scare the shit out of my wife who came running out of the house to see what's going on! She grinned at me and said "Ah Ha! I knew it had to be you. She's cool with the whole thing. I met her when she was working for me at my fireworks company back in 1988. She's a very good shell builder.

[billofca]

I hope that motor did not rock the earth off its normal orbit!

 

Fly

 

Nope, but it did scare the shit out of my wife who came running out of the house to see what's going on! She grinned at me and said "Ah Ha! I knew it had to be you. She's cool with the whole thing. I met her when she was working for me at my fireworks company back in 1988. She's a very good shell builder.

[dagabu]

Bill,

 

If I may, I would like to share some of my observations of your post with you.

 

"The top tip of the spindle was still visible, so I finished it with a clay plug (about 3 heaping teaspoons) in one press increment at 2,000 psi."

 

Any fuel that is above the spindle is considered delay, it is this delay portion that allows the rocket to keep going up for a ways and then tip over so that a shell can be given the perfect viewing position every time. The first delay to try is the same fuel you are using, go for a full ID for the first delay and see how it goes. I prefer 3 seconds delay and I dont press a bulkhead of clay anymore since I found several delay fuels that burn fast enough. The beauty of this design is that you dont have to drill the passfire hole in the bulkhead.

 

Depending on your tooling and the thrust of your fuel, you may be able to use shorter sticks then what the books call for but best to shoot your first with a 4'-1/4" stick the first time. Yes, the Royobi bench top is a fine saw for small stuff but you will not be able to rip 2x4s with it. They sell the same saw with a floor stand too, I use that one for rocket sticks. I modified the guide plate where the blade comes through the table with a new plate from Rockler and slowly raised my thin kerf Freud rip blade through it. I found this to be the very best system to cut sticks.

 

While you are at HD, go check out the scrap bin, you will find 4' sections of tongue and groove pine boards painted green on the end for $.50 each. They will have some warp but I consider 1/4" OK to cut. I rip them in 1/4" strips and then run the strips through on their side to give me 5/16" x 1/4" sticks. I spend a couple hours a year cutting sticks, remember the ear plugs!

 

I also save the saw dust and and mix it 50/50 with creamer for creamora bombs.

 

I also suggest that for silent delay testing you just throw some small stars in the extra tube above the delay and tape them in so that when the delay burns through, you will see the stars light.

 

-D

[Ralph]

Not wanting to disagree with a great rocket maker on the subject of rockets but the fuel above the spindle can and often does still contribute to flight it just continues to burn as and end burner ( if not I have been imagining that they go much higher and been wasting lots of fuel buy having rockets with spindles only 1/4-1/3 of the way up lol)

[dagabu]

Not wanting to disagree with a great rocket maker on the subject of rockets but the fuel above the spindle can and often does still contribute to flight it just continues to burn as and end burner ( if not I have been imagining that they go much higher and been wasting lots of fuel buy having rockets with spindles only 1/4-1/3 of the way up lol)

 

Ralph, that's a great point but I think that wit the mild fuel he is using that its a core burner. An end burner or a whistle motor are different animals altogether and yes, they do rely on the initial thrust of the short spindle and then us the thrust of the grain burning from end to bulkhead for the remainder of the flight.

 

Also noted is the lift, there is not enough usable thrust in an endburner to carry much more then a report.

[Ralph]

if you use a slow delay comp like CM rather than your rocket fuel youll notice a significant altitude difference still though its still producing some lift

[dagabu]

if you use a slow delay comp like CM rather than your rocket fuel youll notice a significant altitude difference still though its still producing some lift

 

I dont understand, can you flesh that out a little more?

[Ralph]

sorry CM= Chrysanthemum of mystery

 

if you use that as your delay comp your rocket wont get as high as if you used the same rocket fuel as you were the core is

[dagabu]

I apologize in advance but I am going to take you to task on that one. If I have time tonight, I will make two 1# BP rockets, one with 1 ID BP and one with 1 CM.

 

I will bet you that the one with CM will travel higher and further. I will put a 5 gram report on top.

[WonderBoy]

Dag I think a better test to show this would be to do one with CM and the other with 1ID BP plus CM. With 1lb motors an ID of BP above the spindle is burned during the thrust phase of the motor, so I think the reason why Ralph says they won't go as high is because he is loosing a full increment or 2 of fuel(depending on inc. size) during the thrust phase. With only 1ID of fuel above the spindle you'll be eliminating the coast phase of the motor and it will ignite the report shortly after the thrust is over, it will still be traveling upwards.

With 1ID BP and no other delay http://www.youtube.com/watch?v=Pj0obU8xbTk

 

With 1ID BP plus delay

 

I was testing a different charcoal in the first vid, but the concept is the same.

[billofca]

Bill,

 

If I may, I would like to share some of my observations of your post with you.

 

"The top tip of the spindle was still visible, so I finished it with a clay plug (about 3 heaping teaspoons) in one press increment at 2,000 psi."

 

Any fuel that is above the spindle is considered delay, it is this delay portion that allows the rocket to keep going up for a ways and then tip over so that a shell can be given the perfect viewing position every time. The first delay to try is the same fuel you are using, go for a full ID for the first delay and see how it goes. I prefer 3 seconds delay and I dont press a bulkhead of clay anymore since I found several delay fuels that burn fast enough. The beauty of this design is that you dont have to drill the passfire hole in the bulkhead.

 

______________

D,

 

Thanks for all your tips. I do know that I need 1 ID of fuel above the spindle, and then a delay comp. This was just a static test on the ground, and as I mentioned in my post, I ran out of fuel near the top of the spindle. My main concern with the test was that the fuel would develop significant thrust and not CATO or blow out the nozzle. In that regard, it was a success. I now have 300 grams of ball milled BP fuel, so the next motors will be done the correct way.

 

I was thinking, have any of you used thermit comp (aluminum & iron oxide) as a delay comp? Also could you post some formulas for delay comp that you are using?

 

Thanks - Bill

[dagabu]

Dag I think a better test to show this would be to do one with CM and the other with 1ID BP plus CM. With 1lb motors an ID of BP above the spindle is burned during the thrust phase of the motor, so I think the reason why Ralph says they won't go as high is because he is loosing a full increment or 2 of fuel(depending on inc. size) during the thrust phase. With only 1ID of fuel above the spindle you'll be eliminating the coast phase of the motor and it will ignite the report shortly after the thrust is over, it will still be traveling upwards.

With 1ID BP and no other delay http://www.youtube.c...h?v=Pj0obU8xbTk

 

With 1ID BP plus delay

 

I was testing a different charcoal in the first vid, but the concept is the same.

 

I agree that that would show an increase in distance traveled but that would be due solely to the delay in addition to the BP on top of the spindle. What we are looking for (as far as I know) is the difference between is the time delay that BP vs. CM affords.

 

D,

 

Thanks for all your tips. I do know that I need 1 ID of fuel above the spindle, and then a delay comp. This was just a static test on the ground, and as I mentioned in my post, I ran out of fuel near the top of the spindle. My main concern with the test was that the fuel would develop significant thrust and not CATO or blow out the nozzle. In that regard, it was a success. I now have 300 grams of ball milled BP fuel, so the next motors will be done the correct way.

 

I was thinking, have any of you used thermit comp (aluminum & iron oxide) as a delay comp? Also could you post some formulas for delay comp that you are using?

 

Thanks - Bill

 

Bill,

 

Congratulations of a successful test!

 

No, you don't need any fuel above the spindle especially if you want a metallic or other tail to be viewed on lift off. If one ID of fuel is used above the spindle, only 1/2 ID will be burned up in the thrust phase of the rocket fuel burn leaving the other 1/2 ID to be part of the delay phase. This is fine, but if you are looking for a particular rising effect, it will not start for nearly a full second after the rocket lifts off.

 

The delay comp may be used directly above the spindle and in my experiences, that is the best way to gauge the delay timing.

 

In my opinion, thermite is very hard to light, it burns at an indeterminable rate and when compressed with enough pressure to consolidate it to a solid so that it becomes a bulkhead, it would be almost impossible to light without continuous heat from a blowtorch.

 

I use delay that is the simplest to use and make, the fuel that the rocket is pressed from plus 30% Ti turnings. I also like Win 39J but simple speaks to me more.

Edited November 8, 2010 by dagabu

[WonderBoy]

Sorry, let me clarify my last post, I got distracted in the middle of writing it and got off topic (basically just delete the last sentence of the paragraph and the videos). I interpreted Ralph as saying that by using a slower delay at the top of the spindle instead of continuing with the same fuel, you will lose some thrust, so the test that Dag proposed would not work very well to test this.

 

And no I haven't used thermite as a delay, why thermite? I often use chrysanthemum #6 as a delay.

Edited November 9, 2010 by WonderBoy

[dagabu]

And no I haven't used thermite as a delay, why thermite? I often use chrysanthemum #6 as a delay.

 

Chr-6 is fine but if you want a brighter tail for marking its flight, use some Ti, Al, Mg/Al or the like to the C-6.

[Ralph]

Sorry, let me clarify my last post, I got distracted in the middle of writing it and got off topic (basically just delete the last sentence of the paragraph and the videos). I interpreted Ralph as saying that by using a slower delay at the top of the spindle instead of continuing with the same fuel, you will lose some thrust, so the test that Dag proposed would not work very well to test this.

 

And no I haven't used thermite as a delay, why thermite? I often use chrysanthemum #6 as a delay.

 

yeah you interpreted it right lol

[WonderBoy]

Oh yeah, I forgot to mention that part. I add about 7-10% large flake Al after milling. Ti gives a longer tail, but I often ram my BP motors so I stick to Al. Edited November 9, 2010 by WonderBoy

[billofca]

Hi folks,

 

The reading here is informative and helpful. I would like to know the formula for "Chrysanthemum #6" and "Chrysanthemum of Mystery" that were mentioned in above posts for a delay comp. Can someone post them for me?

 

Also, I have 325 mesh titanium; can that be used safely with say 5% added to the delay comp (no milling, just a simple mix) and with just hydraulic pressing, no tamping or ramming? I know it can be a problem with perchlorate comp, but here we are talking only about BP comp using KNO3. I can get the larger particle size titanium, but 325 mesh is what I have on hand.

 

I also plan to test in the future a mixture of KNO3 and Amorphous Boron as a delay comp for daytime model rockets w/ parachute recovery. Boron is an expensive chemical that runs about $80/lb, but I have several pounds of it on hand from my days of making Nomatch igniters. It might prove to be an interesting experiment.

[Ralph]

Hi folks,

 

The reading here is informative and helpful. I would like to know the formula for "Chrysanthemum #6" and "Chrysanthemum of Mystery" that were mentioned in above posts for a delay comp. Can someone post them for me?

 

Also, I have 325 mesh titanium; can that be used safely with say 5% added to the delay comp (no milling, just a simple mix) and with just hydraulic pressing, no tamping or ramming? I know it can be a problem with perchlorate comp, but here we are talking only about BP comp using KNO3. I can get the larger particle size titanium, but 325 mesh is what I have on hand.

 

I also plan to test in the future a mixture of KNO3 and Amorphous Boron as a delay comp for daytime model rockets w/ parachute recovery. Boron is an expensive chemical that runs about $80/lb, but I have several pounds of it on hand from my days of making Nomatch igniters. It might prove to be an interesting experiment.

 

 

 

here are a couple other charcoal streamers to

 

Tiger tail : Shumizu

Potassium nitrate 44

Charcoal (Airfloat) 44

Sulfur 6

SGRS or Dextrin 6

 

Chrysanthemum 6: Shumizu

Potassium nitrate 55

Charcoal (Airfloat) 33

Sulfur 7

SGRS or Dextrin +5

 

 

Chrysanthemum 8: Shumizu

Potassium nitrate 49

Charcoal (Pine airfloat) 40

Sulfur 6

SGRS or Dextrin +5

 

 

 

Chrysanthemum of mystery : Shumizu

Potassium nitrate 45

Charcoal (Pine airfloat) 50

SGRS or other water activated binder. 5

 

Spider stars : Source unknown

Potassium nitrate 54

Charcoal (Airfloat) 32

Sulfur 7

SGRS or Dextrin 7

 

Name: Gold Spiderweb

Source: Bill Ofca

 

Potassium Nitrate 53.571

Charcoal 32.143

Sulfur 7.143

Dextrin 7.143

Notes: Ball mill. Cut or pumped wet.

325mesh ti is alittle bit fine (your tail might end up being just a bright dot) but its safe to press though again with 325mesh ti its starting to get friction sensitive so treat the composition with respect

why just daytime boron is rumored to give a rather decent green flame in a similar way to zink does would probably be pretty nice at night to

[dagabu]

Bill,

 

Yes, you can add 5% but I have used up to 30% and it still lights.

[billofca]

Bill,

 

Yes, you can add 5% but I have used up to 30% and it still lights.

 

D, I chose 5% based on my previous studies for flash which uses sponge titanium, and whistles (sodium salicitate) that used 100 mesh flake titanium, where I discovered impact sensitivity gets pretty scary at 10% and above. In the past, I always used 6% in salutes and whistles without experiencing an accident. Other pros in the business also said don't go above 6%. Those were perchlorate oxidizers. I would tend to believe it's not a problem with KNO3, but being such a small particle size at 325 mesh, I still want to keep it low until I get around to doing a "hammer" test.

 

I flew my first stick rocket today. A 3# size with 60-30-10 ball milled mix and pressed hydraulically. This time the fuel completely covered the spindle with another 1 ID increment, then a clay plug (no payload). The thing took off like a bat out of hell and flew so high it went clear out of sight. Yeah baby, now that's what I'm talking about! I will use a delay comp when I get around to using some form of pyro payload.

[dagabu]

WHOOT!!!

 

Happy first rocket day Bill!!!

[billofca]

WHOOT!!!

 

Happy first rocket day Bill!!!

 

Thanks, D! I have now smelt the smoke again after taking a 15 year break from pyro. (Sniff - ahhh, the smell of beer farts in that spent rocket casing!)

 

I am inspired, thanks to the great advice and encouragement found here from all you good folks. At 63 years old, I am still happy to get my hands black from charcoal. More rockets will be made, and more chemicals will be bought so I can advance to some very nice payload ideas I have.

 

First, I have more testing to do with delay comps. Many thanks to "Pyrotechnician" for posting the Chrysanthemum delay comps.

 

Bill

[billofca]

Quick question. Are the chrysanthemum delay comps ball milled, or are they a simple mix?