HyperTEK Experimental Motor Research

I got a 54mm HT Bell to AT closure adapter from Wayne at NowHybrids. (He has no more - but bug him, esp for some in 98mm size :)) This will provide me with a nice sport/ex combo for 54mm Experimental Hybrid motor work.

First Flight / Test

The results of my first test / flight are indexed here. April 10, 2005 at Whitakers WELD.

54mm HT/AT EX

Jamming this stuff here for lack of a better place ... yet...

Wayne: "I have flown with the 1280 case and the440cc tank. I believe you can squeeze out more total ISP with the 1760case, but only the test stand will say for sure! Of course, the 835 tankcould be used also, most likely with the 1760 AT case. I have used 1.5 inch polypropylene pipe with a sleeve to bring up the OD to the AT case ID"

The 440 tank has usable (for my heavy rocket) ISP of about 745 NS as a J240 on the .125 orifice
The 880 tank has a max ISP of about 1285 as a K240on the .125 orifice and 1000 as a J317 onthe .172 orifice

AT 1280 case; AT 1706 case The 1706 case might be right when switching to a "real graphite nozzle" to accomodate the length.
It's instrumental to look at an AT 54mm reload instructions for the 1280 case. Such at this one.

What I have right now is a 835cc tank and both 835cc and 440cc tank dip tubes. So, for some tank weight penalty I can simulate ozidizers from both tank sizes.

HT J-Grain PDF; and the J Motor System; is part of the HyperTek Motor line (over view drawings pdf);
The AT 1280 54mm case is about the same length as the HT J motor grain, so we'll start with that. It's also the case that AT used with their system when it was available.

This does beg another question, and that is the tie down strap. One must now either mill slots in the AT closure or use eye-bolts in the rocket itself to loop it through. I milled slots in the AT aft closure, but it is perhaps problematic as if a recessed retainer is used, such as an Aeropac, the slots are covered.

For 1.5" pipe, in 1280 case, and my current injector, the pipe needs to be 24.5 cm long or 9.646" long (say 9 5/8" long)
For 1.5" pipe, in 1706 case, and my current injector, the pipe needs to be 33.0 cm long or 12.991" long (say 13" long) (this is incorrect due to incorrect 1706 case length)

Aft Closure, Tie down, and retainers

Since my nozzles will utilize radial o-ring seals only I decided my nozzle would be healthier if it had a sider flatter bearing surface - so I had a friend of mine face off the inside end of the Aerotech aft closure to provide a nice wide "nozzle washer" base for the nozzle to bear against. I also dremeled tie down strap slots in it. Here is a picture of it, The slots are perhaps problematic as if a recessed retainer is used, such as an Aeropac, the slots are covered.

Custom Nozzle

The Rocket Motor Parts Single Throat 54mm nozzle 1670 looks to be it. Stock with a .455 opening.
GAK! These are $21.95 each (!) For a single use phenolic (!) Nope ..... gonna do something else for that (!).

Ron Zeppin will make nozzles to spec for about $25 each. I've designed a nozzle for PVC Pipe and here is the dimensioned drawing. It's designed for a dash 326 o-ring as a radial seal to the case, and also a 326 as an axial seal to PVC Pipe in a manner complimentary to the HT-AT adapter. Here's the finished product.

As an alternative, here's an AT EX Nozzle I got from Ken Allen. I'm not sure it's the style I want, as I'd like radial sealing o-rings, rather than the compressive AT style seal, but I might give it a try.

This candidate nozzle is 1.5" OAL. The outer step is about 3/8" long or so. The OD of the outer step is 1.872 which is the step to fit the AT 54mm liner tubing. If you consider just those dimensions in the AT 54mm nozzle dimensioned drawing you've pretty much got the picture. The interior transition is radiused smoothly.

I passed on the one from Ken. The outer step is sized for AT liners, but they're very expensive. I'd rather continue to work with Loki liners as for solids. I'd also like a more "Loki Like" nozzle with one if not two captive radial sealing o-rings. You can do as others and scrounge used medusa nozzles from the folks who're tossing their flown 54mm AT motor nozzles as trash.

HyperTEK to Aerotech Adapter Modifications

I've spec'd some modifications to the54mm HT Bell to AT closure adapter that I have. There were different ones, so these modifications may not apply to all. This set of modifications provides for a #224 o-ring radial seal outside to the case, then a step shoulder to fit the inside of schedule 40 pvc pipe. The length of the step is calculated to allow the pipe to compress the #224 outer radial seal o-ring by 0.010 or so (as it's a bit light on it's squeeze at 8% or so). It also has an o-ring groove for a #220 o-ring for a radial seal to the inside of the schedule 40 pvc pipe.

Casting Aids

I'm having a set of custom casting bases made up for 1.5" pvc pipe. They complement my nozzles and modifications to the Mrazyk Adapter. It's a system now really. The casting bases main point is an o-ring seal on the base as the low viscosity liquids have been known to leak out small cracks and a mess is, well, very messy. Here's a pseudo dimensioned drawing of my casting hardware design. Note that I've also got a top collar. These two ensure that my top and bottom grain seals are both per-spec. Anything that pushes up the inside I can dremel away to oblivion.

Here's the as-built of that set of tooling. Many thanks to Jonathan Carter for making that set for me!

M Class EX

This type of approach is likely where I'll now go for my L3 Cert Project . With a 98mm variant of this type of adapter, which Dave Fitch of Florida has flown, would allow me to meet my goals of a good Sport and EX path with the same hardware with the bonus of being of a suitable length (~44" in 98mm versions) of allowing a "more standard" length rocket (vs accomodating the 78" long RATT M-900) and also my tertiary goal of showing the local L3 APCP crowd that they can stuff and/or switch to sport and EX hybrids in their L3 birds essentially without modification.

Experimental Grain Data

The grains are for the 1280 and 1706 cases. The 1280 case is 11 21/32" long and the 1706 caseadds 3 5/16" which is 14 31/32" long (I wonder if that is really supposed to be 15" long)

So our 1280 case grain pvc casting tube, per this system, should be XXX long, and a 1706 one should be yyy long.

Misc HyperTEK Grain data

J grain. 0.5” nozzle; 1” injector section; remainder slightly smaller (1/16”?) Outer 1.730”; 387.7grams / 388.8 grams

JFX; 31/64 < nozzle < 0.5 ; same core; outer dimension 1.495”; 329grams

Inner length 9” on the step to nozzle; injector groove 7/8”

835cc vent tube – stinger portion 6 5/8”

440cc vent tube – (need).

300cc vent tube – 4 3/8”

J motor length, bottom (inside) to vent 11"

“; top (outside, far aft) to vent “

Misc HyperTEK Thread Data

Specs on threads for Hypertek

1 3/4 -8 UN 3B

Or in metric

44.45 mm x 3.175 4H

Matt Del Castillo
Ballistic Brothers Rocketry
Matt @Ballistic Brothers DOT com
www.TheRocketShop.com

Candidate Experimental Grains

HyperTEK Experimental Motors

HyperTEK Hybrid EXperimental