Відео

2020 (20mm x 20mm) would also be a great size. All of it's dimensions are just a little smaller than the 1010 (1"x1") You just need to buy the proper size rail buttons for your rail. I just looked on rail-buttons.com and they do have mini-buttons available for a 20mm rail.

I see where you would think that. The epoxy ensures a tight and air-tight seal on the ignitor powder. The epoxy gets blown out when the ignitor is ignited.

Two sources... I have a musician friend that makes some of my music and sometimes I use AI music from udio.com This video uses music generated on udio

@@rotaryrocketry I shall look into this and see if it can help me with my needs. Thank you for the tip. Great rocket motors, by the way... I almost blew my head off with a failed motor ignition about 30 years ago... Good times. (~_^)-b

hmmm... I am familiar with the test caps. Not sure where I would integrate that into the build but definitely something I will keep in mind. Thx.

It's something that has been suggested and I will be looking into it.

Single use.

It gets our 4" Eliminator series of rockets to around 1200 feet.

Although sous vide would provide the perfect temperature, you would not have the ability to mix the fuel to get it well blended as it heats. I suppose you could kneed the fuel in the bag once it reaches temperature but I'm not sure if that would be a good blend. Interesting idea though. One down side here is that most people don't have a sous vide machine.

@@rotaryrocketry I meant... Assuming the sugar and potassium nitrate powders are already properly mixed (using a plastic box, and shake?), we are only talking about blending the powder with the corn syrup. I think you can use the wife's Kitchen Aid mixer with a dough hook. The problem of mixing powder and liquid into dough like consistency has been solved by using a machine long time ago, not at White Sand, but in a kitchen. I am quite sure Orbital ATK doesn't stir by hand, most likely using some custom bigger mixer. And, I would use an Anova Precision Oven to do no water bath sous vide ($500). However, a cheaper $100 sous vide stick should do fine. The one good advantage, if it works, is that you can make large batches without having to sit there and stir constantly. Just throw the bags in and let it go. Just walk away.

I'm sorry you feel that way but that is your right. If you care to watch the followup video, you will see that the motor is actually successful. And I am in fact NOT dangerous. We take very careful steps to ensure that our testing is done safely.

@@rotaryrocketry What’s dangerous is people seeing this and thinking that PVC is ok. Are you with NAR or Tripoli?

Excellent question... I did use the earplug to block the nozzle in one of our other motor build videos and it works great... Except... The fuel gets stuck to the earplug and the earplug tends to break when you try to pull it out. With this current system, the earplug is reusable. Silicone, ptfe or spray cooking oil all work well for core rod lubricant.

Interesting... Unfortunately, neither of my drill presses have a "reverse". I guess the manufacturer thought it would be of no value to turn drill bits backwards.

@@rotaryrocketry Google "reverse spiral drill bits" or "left-handed drill bits" - Harbor Freight have them for not crazy money. That lets you run the drill press in "FORWARDS" and still spin the bit in the opposite direction. I'm not convinced that this makes better holes in UPVC though...it just makes me wonder if I'm some kind of tool hoarder to actually own a set!!

Well... ANY tool can be dangerous.

@@rotaryrocketry My 6" spirit level is only dangerous if you attempt to swallow it - but otherwise, you're right. But it is a matter of degree of injury and odds of it happening. Any circular cutting device that doesn't have some kind of retracting blade shield is inherently a LOT more dangerous than one with such a shield.

As long as the wax does not disintegrate instantly from the heat in the motor. If it were to disintegrate before the motor was finished burning then that would expose an area of the PVC to the hot gasses.

@@rotaryrocketry I imagine it would melt, but I wouldn’t think a coating of wax would make that big of a gap. Maybe a coat of some spray can sealant to create a moisture barrier would be enough? Either way, it’s a minor step, and epoxy already works! 🤙

I guess in theory, yes, it would have to shrink a small amount.

The corn syrup makes it so you end up with a nice pourable fuel at a fairly low temperature of 210 to 230F. YES there are substitutes... We did a video series testing some... Here is a link to the playlist ua-cam.com/video/RD4GXXHC_xM/v-deo.html

We have not measured and charted the trust curve for that motor yet. But as you see at the end, it does a great job of launching our 4" rocket to around 1000 feet.

I don't have one to measure because I have not built another since the last one exploded about 3 feet after liftoff using an new experimental motor. I looked back in my videos and I had mentioned that one of these was 1260 grams. Pretty sure that would have been weight of rocket, nosecone, flight computer & parachute. (not including motor weight)

@@rotaryrocketry impressive!

I have used Richard Nakka's SRM spreadsheet quite a bit to help in motor development. Mostly just to get an idea of a good starting size for the nozzle and then I fine tune it with trial-end-error from there. For this design, the outer surface, top & bottom are inhibited. The only uninhibited surface is the core.

@@rotaryrocketry thank you very much.

It's brand spankin' new.

I guess I don't speak that language.

True, not all measurements need to be exact... But it worked... That's what matters in the end.

Sure, there ARE measurable differences in performance with fuel-load variances, but how WOULD you measure them from the ground, and why?

I think the original comment was talking about the fact that my measurements for drilling holes was not very accurate. But the design of this motor is so simple that the measurements don't need to be accurate. As for ground testing... I just have not had any need to do a ground thrust test on this motor. It lifts our small 3" rockets to around 800 to 1000 feet high so I really don't need to know any thrust data at this point.

@@rotaryrocketry If you know the length of the rocket - then a video of the launch - viewed frame-by-frame will allow you to at least do comparative tests of two designs by looking at how many rocket-lengths it travels in each frame of the video. Some simple math would get you an actual thrust versus time graph - but that doesn't matter if all you're doing it comparing two designs to see which is better. You can also get the duration of the burn from a static fire test...and armed with both pieces of information, you'll be able to get a decent estimate of the ISP.

All very true... but a bit more that I was interested in doing for this video. I really just wanted to prove that the anchoring cement end caps would not blow out.

A bit off topic for this video. Also, fair to say that I don't have a clue what you are talking about :)

@@rotaryrocketry Basically a microwave driven plasma rocket.

​@travismoore7849 has this been done or is it just theory?

@@Cantbreakitifitsnotfixed I tested the plasma capacitor that arced in the microwave that when turned off had a powerful electrical field. I shocked my self so I know it can make a arc plasma. Andstore energy like a tv flyback system. As for the magnetic accelerator stage I have not made it.

U're a real rocket scientist, for sure!

This is actually a pretty old video and I have changed my fin installation since then. Newer system is similar in design but simpler. I don't use the motor tube design though. Reason I don't do that is because then I would have to find cardboard tubes that fit all my motor designs perfectly.

I realize there's a small amount of corn starch in there but it's typically around 3 to 5 percent. No really enough to worry about and saves me the time of grinding sugar into a fine powder. I have a future project coming up though where I don't want any impurities and then I will be grinding my own powdered sugar.

Be sure to watch the follow up video... That one didn't explode... ua-cam.com/video/NBFxIZ-WiYs/v-deo.html

Also have a look at this one... It's a lot smaller and we have launched it many times... ua-cam.com/video/WrvOPYNQv_g/v-deo.html

Liked the background I take it. I have a few of those from the same maker... They are really well done. Link is in the description for anyone who wants it.

Therein lies the problem... If I make a video without using safety equipment, people complain that I wasn't showing others how to do something safely... If I use safety equipment people say I should not have used it. It's really a lose-lose scenario. I suppose the overall lesson here is DON'T PUT YOUR HAND NEAR THE DRILL BIT - GLOVE OR NO GLOVE. I appreciate your concern though.

@@rotaryrocketry I'm sure you're good at assessing your own risk mate, just throwing it out there for viewers to consider. No shade and thanks for the vids

You are right but also can be dangerous without gloves. Carpenter for more than decade and i have caught my finger in drill bc i was wearing gloves, but then when i didnt wear gloves i stuck the drill bit in my hand when then boom lift i was on shifted and destabilized my force on drill causing bit to take sharp turn into my hand that wss holding wood in position.

@@julybliss4440 Sounds pretty severe, I wonder if gloves would have even helped you there. Hope you didn't suffer permanent damage :O

@@jeremiahbullfrog9288 certain gloves I wear have made stabbing yourself with driver bit less deep, still hurts though. No not any glove will stop the average force you use for some of the fasteners. Yeah I healed. Just bleed pretty bad and deep infection from oils on screw. Any more the Only gloves I will use with drilling are these tight Kevlar coated(similar to nitrile or rubber coated) called "ninjas", they tend to slip instead of catching on bits if they make contact. They make different colors ones for different purposes or job task. But heck even the time I was wearing looser gloves and caught in bit, it about dislocated my finger, hurt like hell and jammed knuckles and finger joints. Journeyman was yelling at me that he has seen it snap the bones in fingers when getting caught. Power tools are dangerous no matter what, but like you say it's important to not be careless and dont use loose, holey, or frayed gloves.

The nozzle size is extremely important. Reduce the size and the motor is likely to explode. Increase the size and you reduce the thrust. We don't just pick these numbers randomly, we experiment to find what works. Nozzles are measured in 64ths of an inch, so 3/8 would be a #24 nozzle. That's 5 sizes bigger and would greatly reduce the thrust, possibly to the point where the motor would not even be able to lift a rocket.

Many common drill bit sets have 1/4, 5/16. and 3/8" bits. There is not a lot of difference between the 5/16 (=20/64) and 19/64" bit you used. That's just a tiny bit larger and would be a small percentage of thrust less but a bit longer burn time.

True, 5/16 would be a safe alternative. However... As you know... If One is going to be building rocket motor nozzles that are measures in 64ths of an inch then One should have a good drill set with 64ths.

@@rotaryrocketry You could also say if one is going to be building rocket motor nozzles then one should be using a lathe. I was just pointing out that many of your viewers might not have the section of tools you have and bits that others do have that would work just as well. It's not hard to adjust the grain length or core diameter to get the pressure you want that works with the drill set they have.

True... When I used my lathe in some videos a while back, I got slammed a bit in the comments with statements like "You know most people don't have a lathe"

I tried that kitty litter cap thing a few years ago and could not get it to work. I'm sure it was just that I didn't do it right.

@@rotaryrocketry Looks like you have better ways of doing it anyway. My rockets are a little smaller. The biggest I've done was 1 inch so far using kitty litter

I'm pretty sure when I was trying that, it was with 1" PVC also. I was trying to copy something I found on UA-cam... Of course for him it worked great... For me, it was an epic failure...lol

Oh no... Single used motor... No refurbish.

No, but I think you just did.

I know they can be purchased cheaper but because I only buy a few at a time, I get them locally to avoid shipping costs. I will look into that RTRC... Sounds interesting, thanks.

The military has been using fiberglass tubes in weapons for a long time. The tubes MLRS fire out of are fiberglass. LAWs and AT-4s too. The Carl Gustav recoilless has a fiberglass tube too. It's impressive what fiberglass can take.

hmmm... Only everyone who makes rocket motors in the USA. Nozzles are measured in 64ths of an inch so this is a #19 nozzle.

Lol if 64ths get ya wait till you find out there are number, letter, fraction, metric and SAE sizings.

@@rotaryrocketrypppp❤❤❤

Unless you are using a machine shop grade mill to drill it, I's gonna be 3/8..

Blame the king of england

So it turns out that this new design is nearly 30 grams lighter than the end cap design. Both designs fit nicely into a 3" diameter rocket that I mentioned was the style we use for this motor. But rocket design and stability are a topic for another video.

Well, the title is actually phrased as a question... And I did make it clear at the end that this new new design was actually more difficult to build.

@@rotaryrocketry For a one-off build, the extra effort is pretty significant - but if I was batch-building a dozen of them - I think it's unimportant.

Very true. It was a lot more work in the end for basically the same results. However, I found the experiment very interesting and I'm hoping to integrate this new anchoring cement nozzle and bulkhead technique into a much more powerful motor in the near future.

@@rotaryrocketry I do appreciate the technique of softening the pvc, I'n going to incorporate that into my design. Looking forward to your next video.

All great stuff... As usual :) I will note that for this particular ignition design, you must have the ignitor pre-installed. The ignitor ignites a small amount of powdered fuel built into the top of the motor that blows down the core to assist with fast ignition. So the ignitor needs to be built-in. You are correct that I make the fuel in the garage. I realize that nothing is fool proof but the wok system is very safe. The heating element is in a protected space at the bottom and you would have to have some kind of catastrophic mess to get any fuel into that area. I do realize the success rate is only 50% but I was tickled pink to actually have it not explode. I'll definitely be doing more testing before putting it into a fancy rocket. Next test will probably be cooking to an even lower temperature to reduce the burn rate. My motor appeared to have a shorter burn time than Dan's but I'm not entirely sure why... Which actually makes it amazing that it didn't explode.

@@rotaryrocketry I've done 'igniter lighting powder for fast ignition' using 1/8" long dowel up the nozzle and through the core for launching. If doing nozzle-up static testing it is simple to simply lower the igniter powder package (powdered sugar propellant, or black powder, or copper thermite, etc) down the nozzle without the dowel and through the core to the bottom, gravity is a wonderful thing for that. As you say, "nothing is fool proof". It's not just getting something in that space beneath the woke. Nearly all of my propellant melting is done under a cover. I don't know if you've experienced ignition of melted propellant, it makes a large fast fireball with flaming splatter, something not nice to be standing near. You may have confidence in what you are doing but you have to realize many young people watching your videos don't have that experience. What is your Kn? If you want a slower burn rate you can simply open up the nozzle throat. I have three motor cases that use the same steel nozzle. A single grain is a low-pressure long-burn J-impulse. Two grains is a higher pressure mid-burn rate K-impulse and the 'long case' is a high-pressure fast-burning three-grain 50% L-impulse motor. So the shorter burn time than Dan's doesn't mean it should have exploded...it depends on how much of a margin of safety Dan's motors had. I've never had one of my two-grain K-impulse motors explode because the Kn and resulting pressure were relatively 'low'. I've also made motors that were within 10% of the case bursting pressure and had several failures.

I have no Kn or thrust data since I'm simply duplicating Dan's work at this point. I've been hesitant to use tools like Richard Nakka's SRM spreadsheet for calculating Kn. I know it's a good tool but because I've seen varying burn rates based solely on cooking temperature, I feel that tools that attempt to calculate Kn just will not be accurate because they do not account for this varying burn rate. I know I could simply increase the nozzle to reduce Kn, reduce burn rate and therefore increase burn time BUT... Again, since I'm trying to remain as true as possible to Dan's work, I really don't want to adjust the nozzle... yet...