Hybrid Endburners Take Two

[usapyro]

Last year I was quite successful with my hybrid endburner design that allowed me to have a sugar/bp rocket that worked nicely.

 

http://www.amateurpy...ket-end-burner/

 

Then I just realized... That all could be done so much simpler. All I need to do is take the fastest BP meal possible and combine it with the fastest dry sugar fuel possible. Working ratios should be around 50:50 and the range should be around 80/20 to 20/80 BP/Sugar Fuel.

 

The advantage? Sugar fuel packs more power but doesn't have the burn speed to be used in an end burner configuration.

 

 

Also, I should be able to consistently and easily replicate certain effects... Like levitating takeoffs... Just by shifting the ratios of the increments. Or maybe even takeoffs that first go fast... Then just hover... Then take off! If this works, the possibilities are endless!!!

 

It may be even possible to use a combination of sugar fuel and whistle fuel to get a true MEGA smoke cloud space shuttle slow takeoff effect rocket!

 

 

If you ever experimented with slow takeoff BP rockets you know the issues... If you try to do a large nozzle for a slow takeoff the BP grain is burned out before the rocket can gain any height. Small nozzle sizes and higher pressures are more efficient. Sugar fuel alone can't even get things off the ground in an end burner.

 

Testing shall begin in a couple weeks. Anyone here experimented with mixes of dry sugar fuel/bp? Or whistle fuel/dry sugar fuel?

 

 

The key thing I am excited about is that having two mixes which the ratios can be shifted increment to increment easily allows you to do speed changes in one engine with one nozzle size! I want to make a rocket that steadily slows its burn rate as it loses weight so it maintains about the same speed! That would be saweeet!!!

Edited October 8, 2012 by usapyro

[brimstoned]

This sounds like weeks of fun!

What kind of sugar are you planning to use?

[usapyro]

The fastest dry mix I know of. Confectioners Sugar / Ball milled KNO3 + 2% Red Iron Oxide. Probably going to ball mill the KNO3 with the iron oxide.

[Col]

Maintaining stability during the hover could be fun if you rely on the stick

[usapyro]

In my experience as long as the engine thrust maintains positive thrust vs weight... In the very slightest amount, and the center of gravity is behind the engine. It works just fine.

 

Wind can be an issue...

[usapyro]

Here is why this design is much simpler than the one I was using last year...

 

http://i46.tinypic.com/2em2bo1.png

 

No cores, no complications, just plain pressed fuel increments... BP/Sugar Fuel or Whistle/Sugar Fuel. This is going to be some fun testing...

 

Btw, if you can get a dry sugar fuel end burner to work consistently and have good height and speed... Make a video. It is IMPOSSIBLE. I gave up on sugar fuel for anything but cast grains for PVC/Hard casings. Even then the stuff is still massively finicky and you have to be so precise...

Edited October 9, 2012 by usapyro

[usapyro]

Well, the 50:50 BP/Sugar Fuel mix works wonderfully!!!

 

For my tests I used 15g of my hottest willow meal and mixed with 15g of 65/35/+1.5 KNO3/Confections Sugar/Iron Oxide(Red). The KNO3/Confectioners Sugar was also long duration ball milled.

 

I used very short 3/4" id rammed rockets for testing. Very consistent burn... No finicky behavior. Fuel works fine with slightly different nozzle size variations. Was amazed at the distance and power of these rockets with their miniature fuel grains... I was actually kinda jaw dropped by the first rocket with the smaller nozzle... Holy crap... It ended up in the woods like 600' away traveling with around a sixty degree angle. I expected it to land in the field.

 

 

WAHOOO... IT WORKS! BP/Sugar Fuel End burners... ZERO core at all! The BP heavily increases the burn rate to the necessary levels needed for an end burner and HEAVILY reduces the burn rate pressure sensitivity of the sugar fuel. 50:50 BP/Sugar Fuel is definitely a easily usable high power non-finicky fuel that can be rammed or pressed. This stuff rams rock hard easily to a much better density than black powder also. I wonder how this fuel would act with some FeTi in it... Might work!

 

I will test a couple full sized rockets tomorrow with this mix. The 50:50 mix seems as easy to use as BP... And packs much more power! I think that this 50:50 fuel will be able to lift rockets with shells in an end burner configuration just fine. No reason to cool down your BP rockets with mineral oil and bad ratio's folks... Just toss in enough percentage powdered sugar fuel and you have a more powerful rocket with the burn rate you need!!!

 

Btw, has anyone ever used fuel speed changes to increase efficiency as nozzle erosion occurs? I am thinking what could be a great idea is to use a three step fuel speed change. Start off with 50:50 BP/S, then 55:45, and finally 60:40. That might be overkill steep and cato the rocket in flight... Will have to test! I use grog free nozzles.

 

 

BOTTOM LINE... 50:50 BP/Sugar Fuel is an EASY to use fuel that has a MUCH better specific impulse than BP... It even rams and compacts better. Lovely powerful endburner fuel!!! I gave up on plain sugar fuel for pyrotechnic rockets long ago. Too slow/finicky/pressure sensitive, etc... This fuel is as good as it gets! Definitely my main fuel from now on. Ratio's from 50:50 to 70:30 BP/S. I think lower ratio's will probably have too low of a burn rate to be usable for lifting end burners... But, I should be able to get some VERY long duration flight rockets that can't lift much with ratios around 30:70 or so... Hehe...

 

I am probably going to go crazy with this fuel and have containers with tons of different ratios... 20:80, 30:70, 40:60, 50:50, 60:40 etc... Time to make some seriously cool rockets... Ones that steadily accelerate, ones that lose acceleration midway in their flight, randomly change direction then re-accelerate... Haha... Ohhh... The things that can be done with a burn speed tunable end burner fuel! With how well this fuel compacts to rock hardness and sticks together... It probably would make a particularly good nozzle-less core burner that wouldn't have unburned fuel crack off during the burn like what happens with BP sometimes!

Edited October 14, 2012 by usapyro

[usapyro]

Yep... The 50:50 mix just works great. I even tested down to 20:80. 20:80 BP/SF. Those lower ratios can't lift much but they sure make a nice long duration cruising flight!!!

 

Changed my design slightly for use without delay increments. With the high pressure small nozzle rockets this prevents the grain from blowing itself out prematurely. My rockets are particularly prone to this as I use a slick smooth aluminum layer inside my tubes.

 

http://i47.tinypic.com/e985yt.png

Edited October 15, 2012 by usapyro

[brimstoned]

You have the fever!

Imagine drilling an 1/8" hole in the case 2/3's up the planned grain (before pressing) cover with tape.

Spinner at end of flight?

Edited October 15, 2012 by brimstoned

[usapyro]

Huh?

 

Hmmm... That spinner idea could be useful in a two stage rocket. Spin it up then blow off the stick with the separation BP charge... Then you just have a rocket flying straight without a stick!!!

 

That idea might just be workable with a dual stick stabilized design where the ends of the sticks are wired together to stop them spreading during the spin up... Not sure how good of a rotation speed you could get... Hmmm...

[gregkdc1]

Good job on the rockets! I have never made rockets like yours but when I was younger I use to make cored rockets with a hybrid black powder/sugar fuel. I don't remember much about the fuel other than I would ball mill it and then mix it with water until it formed a slurry. After words I would let it dry out before ramming it into little 1/2" rockets. The thing I liked the most about this fuel is that is would make very long tails, like a tiger tail or willow star as the rocket flew. If your not already maybe you could try wetting and drying some of your fuel to see if it makes a better tail, if it doesn’t mess up the burn rate. Edited October 16, 2012 by gregkdc1

[usapyro]

Ill tell you one thing this fuel does... The 50:50 fuel puts out a very nice flame in nozzle-less end burners.

 

Usually when I try to lengthen the tail on a rocket I toss in some FeTi or rougher mesh charcoal. Works better in my opinion than anything else.

[dan999ification]

do the nozzleless endburners fly?

 

Dan.

[usapyro]

Perfectly! Use around a 4-5" core for a 1" I.D.

 

I'm even using starched confectioners sugar and not even the fastest powder possible.

 

This fuel is MUCH faster than you would think... But, your BP must be hot like mine. (See my video.)

Edited October 22, 2012 by usapyro

[Col]

An endburner with a 4"-5" core?

[nater]

An endburner with a 4"-5" core?

 

Well, I light long cored whistles on the end, so they are end burners, right?

[usapyro]

Er, my wording was wrong. I meant nozzleless rocket. All nozzleless rockets are cored... Even with the fastest whistle or BP.