Yankie Posted June 2, 2008 Posted June 2, 2008 I tested those rockets on the weekend, I made 2 KNSU rockets, one 1cm by 5cm and the other 2cm by 7cm, I launched them at an angle and they both flew about 150 metres and reached a height of around 50-70 metres, they had a burn time of roughly 5 seconds. The black powder rockets were 5cm by 1cm and core burners, two had pine charcoal and flew about as fast as the KNSU rockets but with a much shorter burn time. one couldn't lift a 1" shell, then I tried a willow bp rocket and omfg was it fast, I have never seen anything so fast in my life. I have a video of the three rockets i just have to upload them on youtube, will post links later.has anybody ever tried a mix of KNSU and BP? (best of both worlds) or even ramming half the tube with BP and the other half with KNSU.
DIYMark Posted June 2, 2008 Author Posted June 2, 2008 Never heard or thought of mixing BP and KNSU but depending on what side you look at I see it like this - either a KNSU fuel hotted up a bit, or a BP fuel tamed down a bit. The only issue I see with BP vs KNSU is well the fact that for the "equivalent" rocket you need slightly different tooling - which is expected with 2 different fuels with separate characteristics. So far I think they are almost equally matched in performance. Ive made a 70mm X 16mm BP rocket and it burned almost identically to a commercial motor D class motor. Ive also made a 120mm X 16mm KNSU motor and it had similar burn characteristics as to a BP motor. It would burn fast and hard. Im talking in the area of around ~1.2 second for that KNSU motor I made. Where as my brother makes some KNSU rockets (without Fe2O3) and they have long burn times (Far longer than if they had been made with Fe2O3 [so greater than 1.8 times as long]) and they tend to arc in their flight (less power I guess). But then again his nozzles are clay with holes in them and his not bothered to give too much thought into exactly details of the rocket - If it flies its good enough for him. So the way I see it up to now is that yes, KNSU can be a replacement if your bothered to get it to an art (Ideal nozzle sizes, running the case near to its rupture point and even possibly full CD nozzles). However if you want the same power from the same engine but want it to be made "fuss free" (no special tooling/dimensions and high tolerance as there is with KNSU) use BP - Hey its why you find generic motor formulas for BP and not KNSU (I guess)
psyco_1322 Posted June 2, 2008 Posted June 2, 2008 You could make a bp rocket and then use the KNO3/sugar on top of the spindle for a delay. If you add it right to the top then it may add a bit more smoke to the tail. Thats the thing about bp rockets, the delay until the header is pretty short if you just use bp. Pressed whistle would probably burn slower.
Xtreme Pyro Posted June 4, 2008 Posted June 4, 2008 A couple of days ago i decided to try a KNSU rocket but it was a failure sadly, it ignited and started rising out of the tube then it stopped and fell back into the tube and starting smoking... i guess it's time to start back at the drawing board and try again here's a couple of pictures attached if anyones intrested.
psyco_1322 Posted June 4, 2008 Posted June 4, 2008 Probably just another nozzle problem, they need small nozzles to work good and a nice core. Thats why I went to bp. The only time I had bp rockets do this was when I went off the fuel ratios in skylighters 4oz core burner article. There is something screwed up with that stuff.
Xtreme Pyro Posted June 4, 2008 Posted June 4, 2008 Probably just another nozzle problem, they need small nozzles to work good and a nice core. Thats why I went to bp. The only time I had bp rockets do this was when I went off the fuel ratios in skylighters 4oz core burner article. There is something screwed up with that stuff. Yea, the nozzle was small but i think the nozzle blew out after ignition, and i have had the same problem with skylighters 4oz article it doesent seem to work to well
DIYMark Posted June 5, 2008 Author Posted June 5, 2008 Today I shot some BP end burners with 30 - 40 gram BP reports, the rockets were 12mm ID and 70mm long. From the delay between sound and sight they were about 100m up which isnt too bad. Also my brother launched some KNSU core burners with some small tooling I made for him. The rocket size was 12mm Id and 70mm long (3.5mm nozzle using KNSU without Fe2O3). MAN THEY WERE FAST! Once the full core ignited they were gone about 200m up and disappeared - only leaving a huge white smoke trial; all taking place in about ~2 Secs (till apogee). So what am I thinking is WTF Sugar is better than BP? So then I got one of my end burners and using a drill bit I twisted in in the nozzle to make a core and a slightly larger nozzle. I launched it and the rocket had the same height as before (as the end burners) but got there quicker. Hmmm maybe the calculations I did in my the first post were correct - gram for gram KNSU has more energy than BP?!?! Now Im really confused! Oh and all rockets made here used tooling with proper CD nozzles (same angles; only nozzle throat was changed for different fuels)
Deceitful_Frank Posted June 5, 2008 Posted June 5, 2008 You can't really say that either one is BETTER than the other but yes, I believe that KNSU has about 50% higher specific impulse than black powder, 160s theoretical maximum as apposed to 110 or so. Semi-professional enthusiasts using machined steel De-Lavel nozzles can extract 140s from sugar where as estes get maximum 90s from their D-motors IIRC. If I build the best sugar rocket I can with a good clay nozzle and area expansion from throat to exit of 9 times (3 times diameter) I reckon 120s is possible and you may acheive 70s with your BP I suppose. Just to clarify, a rocket with 100s specific impulse can supply 100N of thrust per newton (98.1 grams of propellant) for 1 second or 50N per newton for 2 seconds and so on... hope this makes sence! Sugar needs high pressure for a stable burn (burning surface area 200-250 times nozzle THROAT area) which counts out cardboard for anything over 3/4" wide (core burning is very wasteful of energy as for most of the burn the pressure is far too low to extract decent Isp and the casing's strength (and therefore weight) is wasted and only really used towards the end of the burn. What you want is a cored rod burning on all surfaces and giving a more neutral burn profile. No cardboard tube available more than 3/4" wide is strong enough)BP is very dangerous to use in large diameters due to cracks appearing in the grain.... =BOOM! BP and large Al tubing=pipe bomb where as sugar in cardboard is just disappointing (in comparison with BP or what can be achieved with 32-38mm Al motors. It all depends what you want.
DIYMark Posted June 5, 2008 Author Posted June 5, 2008 Im with you here. KNSU is better - although if your after spark trail effects etc it may be difficult. So far with a 12mm ID the KNSU is fine but as I get towards 16mm paper is showing its limit so Ive gone for PVC. Also you mentioned that core burners is very inefficient - Ive noticed this too due to very progressive thrust. Is there anyway around this for do I have to start making cast grains? Rcandy takes too long but casting grains should be quick (Melt KNSU and pour) and if anything burn better than R candy.
psyco_1322 Posted June 5, 2008 Posted June 5, 2008 Mark if you have some hot bp or some a relatively decent burn rate try making one of your bp rockets without a nozzle. Yes no nozzle just fuel all the way and see how that works. Sugar rockets tend to be the kind that need that top of the core ignition to help get the whole thing lit up quicker.
Deceitful_Frank Posted June 5, 2008 Posted June 5, 2008 Im with you here. KNSU is better - although if your after spark trail effects etc it may be difficult. So far with a 12mm ID the KNSU is fine but as I get towards 16mm paper is showing its limit so Ive gone for PVC. Also you mentioned that core burners is very inefficient - Ive noticed this too due to very progressive thrust. Is there anyway around this for do I have to start making cast grains? Rcandy takes too long but casting grains should be quick (Melt KNSU and pour) and if anything burn better than R candy. I personally prefer rcandy. Jimmy Yawn's mix is around 58:42 Kn to SU and burns well with excellent handling properties. I have tried to take it all the way to 65:35 with recrystalization but it just doesn't work as well and the texture is horrible with a fragile and brittle fuel grain. 60:40 for me works just great with 1/3 of the sugar made up from glucose syrup and you only lost about 3% Isp compared with 65:35 IIRC. I would also be willing to bet that 1 volume of rcandy is more energy dence than the same volume of cast 65:35 as without vacuum degassing its far too easy to get trapped air bubbles in there and a ground suspension of KN in melted SU is never going to be any where near as intimately mixed as a recrystalised and dried out solution of fuel and oxidizer in water! Is making rcandy really that much hard work? Just take 50ml water, add 60g KN with 27g of white sugar and 13g of glucose syrup. Boil and pour into a glass dish. pop it in the oven at 150C til all visible water has gone, give it a stir and spread it out thin. Take a sample and allow to cool on a tile. Snap test yes or no. give it 10 mins, stir and retest. When its close then test every 5 instead. allow to cool to 80C and its mouldable by hand. Does it really take too long?!
DIYMark Posted June 6, 2008 Author Posted June 6, 2008 Making R Candy is no problem. Its just its rarely that I make it the then load motors with it instantly. So this would mean I have to reheat it and doing that on a skillet is a pain in the ass. Is there any other ways to reheat its easily? Also would getting Rcandy, smashing it up, putting it in a coffee mill work? then I could load my motors the same as I would with dry mix?!
Deceitful_Frank Posted June 6, 2008 Posted June 6, 2008 With KNSU its either melt it of make rcandy. Pressing dry mix is inconsistant and suggests core or end burning motors. As I've already said if you want to go down this route then stick with BP. KNSU is all about performance. Check the link below and see something hit over 340mph in 0.4 seconds. You don't get that with black powder. A good result is gonna take time to achieve. http://www.mediafire.com/?tsmxzbbgxsc How about if you don't make the rcandy 'til you know you are going to load the rocket or at least know the dimensions of the grain you will be using? As long as you get all your shit prepared on the table and know what you are going to do it takes seconds to pack soft toffee into a tube containing rolled up paper (to size the grain) and to poking a greased rod through it takes well... seconds! Allow it an HOUR to cool then remove it and put in a sealed bag with some CaCl2 wrapped in tissue and the longer you keep it the dryer and better it will be. If it is not allowed to cool enough even light finger pressure can warp it enough for it not to fit in you motor tube. My free standing grains have just 1mm or clearance around the edges.
DIYMark Posted June 6, 2008 Author Posted June 6, 2008 Good Idea. Last time I make a R Candy rocket (more of a spare of the moment thing...) it was quickly thrown together with an equally as quick CATO at launch Once I get my nozzle tooling Ill give the Bates grain a go!
Yankie Posted June 6, 2008 Posted June 6, 2008 I made a few KNSU rockets today and about 15 BP bottle rockets. the bottle rockets were 1cm ID and 2.5 cm long, they were loosely packed and had a tapering core with a 3-4mm nozzle. they were very consistent and all went about 100M. I had 3 KNSU rockets and two were 5cm long and 1cm ID with a full length core and 3-4mm nozzle, one lifted a fairly heavy rocket body about 50m up, i attempted a parachute but it snapped the leader and melted the chute, so the rocket came down just as fast as the slightly melted parachute. the second one had a lego man with a parachute and it got around 30 metres when the chute charge went off, it melted the chute a bit so it did not open, but still slowed the lego man down. I then made a 2cm ID 6cm long KNSU rocket with a full length core and 4mm nozzle, it got about 10 m off the ground then i heard the nozzle shoot out, yet surprisingly it kept going and ended up about 100-150 metres in the air and landed 100 metres away in a paddock. maybe i have made the first decent sized nozzleless KNSU rocket.
donperry Posted February 28, 2011 Posted February 28, 2011 I must add my results to the RCANDY thread when i make my R candy i do the recrystalized method with Red iron oxide.But i do things as little diffrently. I then take that r candy and ground it to dust. This means i can store it in a powder form and ram my rockets later.I tried that and man.... performed REALLY well. I have a video of it to show too http://www.youtube.com/watch?v=fjlYhE3q8MM rocket was a 3 inches long, .8 inches internal dia, with a 17/64 (.26) nozzle
donperry Posted March 6, 2011 Posted March 6, 2011 And here is a video that i wanted to share with you http://www.youtube.com/watch?v=s_d8DMiY4NE It probably reached a kilometer or so.
pillyg Posted March 6, 2011 Posted March 6, 2011 Don, that rocket is good, but pvc is really bad for casings because if there is a cato, it will fling sharp pieces of PVC everywhere.
dagabu Posted March 6, 2011 Posted March 6, 2011 Outstanding performance on that rocket Don. Could you share what the spindle length was as well
donperry Posted March 7, 2011 Posted March 7, 2011 Really wish I could. The owner of the video did not respond to my questions about design. Pilly. I use PVC with electonic ignitors and stay far enough. I need to add that I used my e- ignitor yesterday and they all lit too well. Paper swelled and shot nozzle out. I must add here that these rockets that are lit from the top of the grain using e ignitors are faster on the takeoff than those lit at the bottom, I.e visco fused. More gases seem to be expelled at the initial burst.
dagabu Posted March 7, 2011 Posted March 7, 2011 I cant light mine from the top, they all pop when I do. I want to try your method of grinding the fuel up and pressing like a standard fuel grain.
donperry Posted March 8, 2011 Posted March 8, 2011 Oh kool, i suggest you do! You must use normal white sugar though. Other mixtures (like dextrose) might be flexible and not brittle enough to be ground to dust. About the catos from top ignition, it seem thats a problem we both have
dagabu Posted March 8, 2011 Posted March 8, 2011 I just cant see spending a lot of money on dextrose so white table sugar (the cheaper the better) is what I use as well. How are you grinding it down? I found that it is to hard to just use a cheese grated on. Yes, I can't even use bare blackmatch to light the top of the rockets, I have to use visco and light the bottom of the grain. I like to think that this is a good problem to have
donperry Posted March 18, 2011 Posted March 18, 2011 I like to think that this is a good problem to have Haha, maybe it is.If you are using Table sugar it is VERY easy to gind using a mortar and pestle. In fact, i can grind quarter kilo in about 5 mins. But the cheeze grater should work to get them small enough to ram or press
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