Certified EX hardware help

[thobin]

Ok I want to buy some larger motors that can be used with EX motors (54mm & 75mm). I'm only aware of a few brands of hardware that you can use EX motors with, and that you can use to certify level 2 or 3 with. I think? Gorilla, AMW Pro-x, Loki and Kosdon. Are there any more, or some of theses aren't certified?

What's the best hardware to go with and why? That kind of stuff with out getting into a AT /CTI is mo betta kind of battle. I'm kinda leaning towards Gorilla but i'm also giving Loki a good hard look too. Help me out here.

TA

 

[jimzcatz]

Gorilla,AMW,Loki,Kosdon are all the same,and are certified for commercial loads. Prices are pretty close,so its up to you and where you want to buy from. Reloading Aerotech cost more for the inert parts_liner,nozzle). The Brand X from Tru-core is the cheapest, and I have some. It is great hardware, but its not certified for Commercial loads.

 

[G_T]

Hardware that will cert level 2 won't cert level 3.

I have AMW and Tru-Core 54mm hardware. They get far more EX than commercial. In the rare case that I want to fly commercial, it will be Pro38 for convenience, or a full K - baby L in the 2550 case.

I have AMW 75mm hardware, pretty much the full set, but the reality is that the collection of cases will likely only get two commercial loads total. One was for a friend's L3, and one for mine. We've had a number of flights and test burns on this hardware set, some under my name and some under other's certs. One of my favorite 75mm cases is an old gold Kosden East case which is somewhere around 4700. For some reason the commercial cases skip this region now. 3500 then to 6000 for AMW for instance.

I'm not all that fond of the commercial nozzles for EX use. In EX, I probably run a higher pressure than the commercial loads. I certainly run a higher Kn - roughly a case size worth. The commercial nozzles are under-expanded for what I do. They work fine, just lose some efficiency.

In EX, one gets to choose the grain geomerty - length, core dimensions, bates, finocyl, moonburner, c-slot, whatever you want. One chooses a liner. One chooses nozzle throat, expansion ratio. It is all up to the EXer. Not many decisions are pre-made, if you don't want them to be.

IMHO, except for rocket kits not being designed for it, I like 88mm (up to small N motors) and 114mm (up to medium O motors). Why? Cheap good enough liners, readily available. When you get into EX, you'll likely find that good liners are pricy, and cheap liners are, well, cheap. You get what you pay for. I've had plenty of burn throughs and splits with cheap liners. But PML phenolic tubing is not bad liner material and the price is right. 88mm uses 3" body tubes and couplers, and 114mm uses 4". If your rockets use rings, then these oddball sizes are a non-issue.

EX is what you make of it.

Get the level 2, and then get with someone to mentor you in EX. Worry about the L3 stuff later. That would be my advice.

Gerald

 

[THarrison]

Hardware that will cert level 2 won't cert level 3.

Not true. AMW 75/6000 has the skid L1400 along with all the M loads.

 

[DeeRoc29]

For 54mm, CTI is super easy for EX. Use spent nozzles and bulkheads. Get liners/casting tubes from Always Ready Rocketry.

 

[thobin]

I didn't mean that I want to use lvl 2 hardware for lvl 3. Im not aware of any 54mm that you can lvl 3 with it. My goal here is just to find out what the differences between hardware and if there is more certified brands out there than what I listed.

Thank you good to know.

Not true. AMW 75/6000 has the skid L1400 along with all the M loads.

TA

 

[G_T]

Just don't count on being able to launch the skid, depending on your launch location and conditions. I wasn't aware of that motor; thanks for the correction!

Gerald

 

[jimzcatz]

Just don't count on being able to launch the skid, depending on your launch location and conditions.

Gerald

Why not? Its a great motor. If you can find the April 2008 issue of Rockets Magazine my 3.75X SWAT made the table of contents page!!! It was the AMW L1400.

 

[CarVac]

Fire risk.

 

[Loki Research]

What's the best hardware to go with and why?

The best hardware is what's best for your needs. There are a few differences in snap ring motors, but the cases are pretty much the same, between the snap rings anyway.

Liners,
Most 54mm and 76mm liners are the same for ALL snap ring motors. 38's are different between some manufacturers and so are some of the 98's. Search the forum and you'll find the differences.

Closures,
The forward closures are different among each, some have "hockey puck" style (flat disk with an o-ring and and threaded for an eyebolt), some, like Loki & Gorilla have wells for tracking smoke and/or delay ejection. Gorilla offers both styles I believe. A few, as with the new Loki 54mm bulkheads, can do plugged with or without an eyebolt with or without tracking smoke, or tracking smoke with ejection, all in the same bulkhead.

Finish,Commercial cases are usually type 2 anodized. (bright color finish) AMW cases, and now, all new Loki cases are type 3 hardcoat anodized for superior corrosion protection. Non anodized cases work just the same, but can be a bear to keep clean and keep the metal from oxidizing/pitting on the inside over the years.

Case Material,
Older Loki 54mm and 76mm cases were turned from Sch80 pipe. The 54mm had integral thrust rings, which fit in just about any motor retainer, and people really liked this. The problem with pipe is the tolerances. Pipe is not as strait and round as the custom drawn tube is. It's particularly troublesome when making long motor cases. After turning down the OD, the wall could be quite a bit thinner on one side than on the other. Unfortunatly the only way to see this is after cutting a finished case in half, done sometimes when repairing a damaged motor case. Most of the time pipe works just fine for motor cases, just not as good, especially on the longer cases. To my knowledge, only AMW, Gorilla and Loki have custom drawn tubing for 54 & 75/76mm cases. I'm not sure about the other diameters.

Thrust rings,
New Loki 54mm cases have smaller external thrust rings placed further aft in order to fit more of the popular motor retainers and to lower cost. They will fit some of the Slimline retainers, but the retainer must be installed dead nuts strait. (very tight tolerances there) The 76mm thrust rings are also lower profile now as well, but they still do not fit the Slimline retainers, nor will any of the other snap ring cases AFAIK.

Lastly, the nozzles.....
How big a difference is there here? I really do not know, because most nozzle vendors either can't tell you what material they have, because they don't really know, or they just won't tell you. (maybe also because they don't really know) I do know that I wanted a better grade of graphite moving forward with Loki. Our nozzles have always been at least of standard quality grade material with first class machining, but I have recently stepped it up here, a lot. See the products page for more information on this and other changes to Loki Hardware.

I have a 54mm #24 (.375") test nozzle that saw 11 firings before it finally showed a crack, and then I fired it once more for $hits and grins (can I do that?) on a 3 grain Loki Blue. It worked fine. It saw everything from 600 to +1,500 psi, red, white & blue loads and the majority were over 1,000psi. Oh and the throat....it still measures .375" I'm very happy with it. (Disclaimer, I did not fire any Spitfire through it. We had a drought here this summer)

I'm not all that fond of the commercial nozzles for EX use. In EX, I probably run a higher pressure than the commercial loads. I certainly run a higher Kn - roughly a case size worth. The commercial nozzles are under-expanded for what I do. They work fine, just lose some efficiency.

Okay, I have to bite here. I’m assuming you’re doing APCP and not sugar.
What is the maximum Pc and average Pc you run each diameter of your motors at? Is this measured on a stand, or calculated on Burnsim?
What Kn ranges do these motors run at?
What expansion ratio do you like to run?

 

[dixontj93060]

... but I have recently stepped it up here, a lot. See the products page for more information on this and other changes to Loki Hardware.

Scott, like this!!! So should I sell off and do a wholesale upgrade on all my Loki hardware?!

Just ordered a couple of reloads from Chris' Rocket Supply I hope to be lighting this year. Also still have that N3800 -- just no rocket worthy to fly it in yet?!

 

[thobin]

What about compatability between reloads from one brand to the next? And what about the spacer system for the gorilla? Like most I would rather spend money on reloads than hardware, any thoughts form those who have had a chance to use it.

TA

 

[G_T]

Hi Scott,

Coming out to Red Glare in a few weeks??? Hope to see you there! Jerry, Al, and I will be burning some Ns in 88mm and 114mm, conditions permitting.

It is easier to answer some of the questions in person because otherwise someone will try what I'm doing and blow up some rockets. But, since you asked, APCP. Kn from about 308 at the low end to up over 450 at the high end. Burn rates from about 1/8"/sec at the low end, to 0.2"/sec at the higher end. Propellant density in the range of 0.059 lb/in^3 at the low end, up to 0.0643 lb/in^3 for one of our denser formulas (at 4% aluminum). Expect the density to go up some more though. Increasing density impulse is one of my goals, as long as it doesn't increase burn rate.

My desired expansion ratio is not a constant, but depends on the particular test. I do stay somewhat underexpanded, mainly to avoid being overexpanded if results differ too much from expectations. It is usually not too far from 6:1, give or take a number.

I have a little test stand pressure data, but the calibration file is @#$@ so it is worthless except for showing the curve. Unfortunately. That data is only for 38mm tests up to 4 bates grains anyway. The stuff we're working with nowdays just doesn't play well with hardware smaller than say a 3500 in 76mm at the small end (empirical result), so probably not such a loss at that. The old prototype propellant that worked well down to small motors just wasn't stable during storage due to what was in it. So now the contents are a fair bit different.

I did accidentally run 4Kg of propellant through an AMW 6000 nozzle (in a 7600 case) in two seconds in a static test. Mistake, but it survived. It was quite loud though! I learned a lesson about opacification in that test. It's not a mistake I'll be repeating though it would be really cool to fly that propellant if I thought I could get away with it.

I think I've provided enough info for one to estimate the actual pressures pretty well. I just don't want people running high Kn just because I'm doing it. My formulas are intended to have pretty low burn rate exponents compared to most, and some of them have exhibited a burn rate plateau such that there is not much difference in burn time with Kn in the range of 150 to 450. My target pressure range is in the 750-1000psi range, low enough not to risk the hardware. These propellants tend to burn very smoothly. It is all a work in progress. Just copying my formulas without duplicating the processing won't duplicate the results anyway.

My 88mm hardware is roughly 3/16" wall and the 114mm hardware is roughly 1/4" wall. I'm not worried about casually blowing them up with a bit of pressure. They are rather overbuilt for my target pressure range.

Numbers are from memory as I'm not around the computer where I have the records. The motor tests tend to all blur together after a while anyway.

Anyone reading this - don't try it! Feel free to talk with me about it in person at a launch though if the direction I'm attempting is of interest to you!

Scott, did I get you the info you needed?

Gerald

 

[jimzcatz]

Also still have that N3800 -- just no rocket worthy to fly it in yet?!

I have just the ride for it....