Letter to Tripoli Prefects

10/21/96

Dear Tripoli Prefect;

AeroTech would like to enlist your help in reaching the members of your prefecture with some important Easy Access/RMS high power product information.

During the course of the past eighteen months, AeroTech has been gathering input from the entire rocketry community regarding an apparent elevated rate of nozzle failure where use of the following four, RMS high power Black Jack reload kits is concerned:

29mm/G75J · 29mm/H97J · 38mm/H73J · 38mm/H112J

(Note: 38mm/I154J and 38mm/I195J have been reliable.)

Given the documentation provided by members of Tripoli (and the NAR) AeroTech found that the frequency of nozzle failures being experienced by consumer use of these four Black Jack Easy Access/RMS high power reload kits to be above average and in need of a "fix".

Though a "fix" in absolute terms is not possible (as expulsion of the nozzle is an intended over-pressure failure mode for all RMS hardware) a significant increase in reliability has nevertheless been accomplished. Please share the following with your prefecture members.

Prior to August 1, 1996, AeroTech redesigned its 29mm RMS molded nozzle for greater strength (while not circumventing any safety margins.)

Note: All 29mm and 38mm Easy Access/RMS high power reload kits utilize the same 29mm nozzle (with the one exception being the 38mm J350W which uses an entirely different nozzle.)

Effective August 1, 1996 to present, all of AeroTech's Easy Access/RMS reload kits (with the exception of the J350W) have been produced with the redesigned 29mm nozzle. It is very important that users of AeroTech Easy Access/RMS reload kits understand this point. Packaging of the redesigned 29mm nozzle has not been limited to Easy Access Black Jack reload kits. For the sake of manufacturing simplicity, the new 29mm nozzle will appear in Blue Thunder and White Lightning reload kits as well (with no change in performance.).

So, how does the consumer tell the difference between an "old" and "new" nozzle/reload kit? The answer can best be explained if you examine the cross-sectional drawings (Figures 1 and 2) on the next page.

In Figure 1, the "old style" Easy Access 29mm and 38mm reload kit nozzle (whether it is Blue Thunder, White Lightning, or Black Jack) is depicted. What is important to note is that the sides of the convergent section (combustion chamber side) are straight.

Fig. 1

 

In Figure 2, the "new style" Easy Access 29mm and 38mm reload kit nozzle (as used in Blue Thunder, White Lightning, or Black Jack reload kits) is depicted.

Fig. 2

 

Note that the sides of the convergent section (combustion chamber side) are now curved. Also be aware that the apparent curvature will vary depending on the average impulse of the reload kit; so don't be concerned if the convergent section of a nozzle in a H97 does not appear to be the same as the convergent section in a H238 as long as it is curved.

What AeroTech Would Like Tripoli Members To Do:

1- Tripoli members should carefully inventory all their AeroTech Easy Access 29mm-38mm reload kits for all examples of the 29mm/G75J · 29mm/H97J · 38mm/H73J · 38mm/H112J.

1- Remove the "old style" nozzles from each of the applicable Black Jack reload kits in your stock;

3- Using masking tape and a pen or marker, identify each nozzle as to the type of Black Jack reload it came from;

3) Package all the tagged "old style" nozzles in a soft mailing pouch along with a slip of paper on which you have written your name, address, and daytime telephone number;

4) Send your package to:

AeroTech, Inc.
Replacement Nozzles
1955 S. Palm St., Ste#15
Las Vegas, NV, 89104

Within 5 business days, we will ship back the appropriate type and number of "new style" Easy Access/RMS nozzles.

AeroTech appreciates your NAR section's participation in our effort to help make your flights with Easy Access/RMS Black Jack reloads among your most memorable.