(Courtesy of Star Rocketry)
Hypertek "L" PML Ultimate Endeavour
Hypertek is a highly efficient low cost alternative to the current popular composite motors. However, how does one construct or modify a model rocket to accommodate the unusual shape of the Hypertek 835cc and larger motor systems? Chuck Andrus wrote an article describing one method he applied to his fiberglass HyperActive. Here is another technique I have applied to my most recent project, the PML Ultimate Endeavour, pictured left with my son Scott, that will be capable of either the Hypertek 1685cc or the 2800cc motor systems.
The Hypertek 440cc motor system fits nicely into any 54mm engine tube as long as it has enough depth to accommodate the length of both the motor system and fuel grain. The larger Hypertek motor systems, however, take a bit more imagination.
The following pictures will show the various views of the Hypertek PML Ultimate Endeavourís booster section. The booster section has two parts: the external airframe and the internal booster assembly. The internal booster assembly slides up into the airframe. This allows easy access to the Hypertek motor system.
Screwing the fuel grain onto the motor system takes little effort and provides a means of venting the N2O out the end of the rocket verses having to drill a hole through the side of the airframe. The vent tube attaches to the motor assembly through the engine motor tube.
Slide the booster assembly, after fully assembling the motor system to the fuel grain and attaching the vent, up into the airframe until it comes to rest against the booster block shown below left. The booster block takes the force of the engine thrust and transfers it to the airframe.
The screws only secure the airframe skin to the booster assembly (picture to bottom right shows screw along bottom edge of airframe). The bulkhead is far enough down the tube to allow either a 1685cc or 2800cc "L" motor system.
In my next article I hope to show pictures of my "L" project soaring into the sky and floating gently back to earth. I plan on using an Adept ALTS25 and a Blacksky ALTACC for my electronics. I will provide the results of the maiden flight.
Results of March 27th 1999 flight:
Hypertek L460cc with .172 orifice; Adept ALT measured 3794'; ALTACC measured 3810' at 16.625 sec; Max velocity was 425.07 ft/sec at 3.75 sec; Max acceleration was 262.22 ft/sec2 (8.2G) at .6250; Min acceleration was -41.46 ft/sec2 (-1.3G) at 6.5625 sec; Main chute deployed at 1200'; Sunny 60F light wind.
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