ERC Helps Develop New Test Method for Rocket on a Rope


The test team at the Missile Flight Test Division on ERC’s Missiles Sensors Test Directorate (MSTD) contract typically consider a successful test one that literally ends with a boom! The flight testing range hosts a wide range of test capabilities including live missile firings, target fabrications, weapons systems checkouts and qualifications, and warhead lethality testing in static and dynamic environments, just to name a few. The Rocket on a Rope (ROAR) test configuration is one of the dynamic deployment capabilities that has a proven track record. Recent developments, including superior and innovative designs by ERC’s team have helped the ROAR program add a reusable deployment mechanism by incorporating a jet engine instead of a rocket motor as the propulsion system. This serves two purposes, a) it eliminates the destructive nature of the test and re-use of hardware that drives down costs and speeds up time between tests, and b) provides greater thrust control to give constant velocity over time to the projects that require it.

The entire team at Test Area-1 supports the program on test day, but it was Haden Gregg and Ernie High who worked hand in hand with the customer’s requirements to single out jet engines as a solution, run the numbers behind the thrust curves required, and innovate the full on solution which involves both initial launch catapulting and braking at the end of the test. Haden also built and wrote the control logic for the on-board electronics. Mitch Hinkle and Dale Lee head up our CAD/Fab functions and re-tooled the design relentlessly as 2 different engines were tried and many nose cones and fuel tanks have made their way through the 3d printer. David Smith wrote the control software user interface which allows the test team to read engine parameters as well as fly the system over wifi.

We appreciate all the hard work they have done and are continuing to do in the development and testing of this new and exciting system. Read more about ROAR in a recent article in the Redstone Rocket written by our customer, Test Engineer Collyn Mann.

New Test Method Lassos Guided Flight Data

Have you ever seen a 2.75-inch rocket motor launched from a helicopter? They are not exactly known for their accuracy. However, the rockets do serve as an excellent and repeatable propulsion source for the Rocket-On-A-Rope test method. That was the thought process that created what is now a very cost effective method for testing an abundance of developmental items ranging from prototype warheads to advanced target detection devices.

The Redstone Test Center’s Missile and Sensors Test Directorate has partnered with the Aviation and Missile Research Development and Engineering Center to support ROAR testing at the Missile Flight Test Division, Test Area 1. The alliance between the two organizations has brought greater expertise to the test community along with an increased knowledge base and adaptive test nature. This affiliation is of great benefit to the test sponsor as they can draw insight from two exceptional organizations during the test event.

“Working with Test Area 1 while executing Rocket-On-A-Rope programs allows us (AMRDEC) to leverage our expertise in warhead and sensor development with RTC’s skills in system control, advanced data acquisition, and test methods. This innovative test system has provided predictable and proven light profiles for a variety of data requirements for both legacy and new technology programs. The combination of organizational insight is powerful and results in a proven product for the test sponsor,” Greg Johnson, AMRDEC ROAR senior engineer.

The ROAR test method is unique in that it utilizes high-tension ropes to guide the propulsion source, outfitted with the test item or target of interest, in a dynamic environment to a very precise location downrange from the launch point. Once the weight of the test article is known, it is a matter of a few calculations to determine where and when the test event will occur on the ropes. This type of accuracy ensures repeatable test results. The ROAR setup is relatively simple and includes the ropes, rope hardware, anchor point, winches and an adjustable height tower. The setup can move to different locations on the range to accommodate a variety of safety fans.

The customizable nature of ROAR testing does not stop at the test item. During the last year, the Missile Flight Test Division has developed a new air-breathing propulsion method as an alternative to the solid rocket propellant. The new, kerosene-fueled jet engine is a miniature version of what is found on jet aircraft and has been adapted for ROAR testing. Affectionately deemed the “Acceleration Controlled Model Engine” or ACME for short, it successfully meets the criteria posed by one test sponsor that had a requirement to fly at a constant, subsonic velocity for 150 meters. So far the addition to the test method has meant the procurement of two “mini-jet” engines, but more are expected in the future.

This subsonic, constant velocity alternative to rocket motors has opened the door for a variety of test programs, especially in the realm of unmanned aircraft and radar systems. The ROAR method has always filled a niche between test stands and full-up missile testing and the anticipation is that the ACME testing will do the same in the unmanned aircraft and sensor domains.

Article By Collyn Mann, Test Engineer-Redstone Test Center, with permission

1 Comment

  1. Matt on March 22, 2014 at 2:24 pm

    Great team, innovative results!