Air Force

April 13, 2012

TPS students analyze C-12 Huron rudder forces

Tags:
by Laura Mowry
Staff Writer
Air Force photograph by Chris Neil
The tufting visible on the tail of the C-12 Huron played a critical role in the SPINAL TAP test management project. It allowed the team to investigate the force-lightening anomaly using flow visibility. Testing was done during a series of maneuvers performed over the course of six sorties.

Karl Major, a civilian test pilot at the United States Air Force Test Pilot School, has been studying and flying the C-12 Huron for years. Over the years, he noticed an interesting phenomenon with the aircraft while experiencing sideslip.

Under certain conditions, the more the pilot would push on the rudder pedal to generate sideslip, the less the force the pilot would have to apply to get the rudder pedal to deflect. This was not intuitive and not a very desirable characteristic. Hoping to learn more information about the force-lightening anomaly, Major tasked USAF TPS students to investigate the situation further.

“As students go through TPS, they learn the theory of how and why an aircraft behaves in a certain way. It is important to their education to understand how different aspects might affect the flight characteristics,” said Major. “In this case, TPS students will discover the C-12’s rudder force anomaly on recurring curriculum rides.”

With Baughman leading the way, USAF TPS students Capt. Roman Underwood, Capt. Scott Rinella, Maj. Jesus Cosme, Capt Carl Beckey and Singapore exchange student Maj. Bellamy Chia of Class 11B accepted the challenge for their test management project.

The project is the culmination of the students’ intensive year-long Masters Program at the USAF TPS.

According to David Vanhoy, USAF TPS technical director, completing the test management project presents unique challenges for students who must balance the successful completion of the project with meeting additional curriculum-based requirements.

Air Force photograph by Chris Neil

The test management project SPINAL TAP, short for Science Project in Aircraft Laboratory, Tufted Aircraft Panels, began last December hoping to investigate the phenomenon with flow visibility on a tufted vertical tail. Two sorties were videotaped from a C-12 chase aircraft, allowing the team to review data and visually identify how the tail of the aircraft responded during the various airspeeds and aircraft configurations.

“It’s truly amazing what our students are able to accomplish,” said Vanhoy. “And the SPINAL TAP folks are no exception.”

The test management project SPINAL TAP, short for Science Project in Aircraft Laboratory, Tufted Aircraft Panels, began last December as the team prepared to look into the phenomenon by using a flow visualization technique on the C-12’s tufted vertical tail.

Tufting refers to the strings of yarn attached to the surface of the aircraft’s tail, which allowed the students to visually monitor their activity during flight, particularly when performing maneuvers that induced sideslip to the aircraft. This technique shows locations where the airflow is attached to the surface of the tail, where it has separated from the surface, and the general direction the air is flowing along the surface, all phenomena that are otherwise invisible to the eye.

“Looking at one subject in greater detail can be extremely valuable,” said Baughman, USAF TPS, SPINAL TAP project manager. “The safety of the C-12 rudder was never in doubt, but it is certainly an interesting characteristic and we were excited to have the opportunity to look further into it.”

Steady heading sideslips, rudder doublets, asymmetrical thrust, and the “Webster” flight test maneuver, created by the students, were used to induce sideslip while testing various airspeeds and aircraft configurations.

According to Baughman, the Webster flight test maneuver was named after the group’s technical advisor, Fred Webster who works with the 773rd Test Squadron at Edwards. The maneuver was designed to gather data that Webster built software to analyze.

Of the four maneuvers performed during flight, the steady heading sideslips turned out to be the most effective for gathering data.

“Normally as a pilot, I would continue pushing on the rudder pedal to get out to where I need to be,” said Baughman. “But, if I were to instantaneously push on the pedal to get a fixed amount of sideslip, then that’s where you start seeing the pedal force lightening in the C-12. The steady heading sideslip maneuver is the best way to see this happen since we’re taking snapshots at different angles of sideslip.”

Early on in the project, it became clear that there were physical challenges associated with the SPINAL TAP test management project. Performing steady heading sideslips required pilots to apply approximately 150 pounds of force on the rudder pedals for extensive periods of time throughout each of the six, two-hour long sorties.

“We quickly realized that flying these maneuvers turned out to be quite a workout,” said Baughman. “We decided to take two pilots on each sortie so that we could alternate and get a much needed break.”

Two of the six sorties were videotaped from a C-12 chase aircraft, allowing the team to review data and visually identify how the tail of the aircraft responded during the various airspeeds and aircraft configurations.

The team’s preliminary findings indicated that the anomaly is more subtle than the force lightening that Major and the students had originally thought.

“When we started the testing, force lightening showed up in the data right away,” said Underwood. “However, as we continued testing, we started to see different results.”

The data also seems to indicate that aircraft configuration plays a much larger role in force change than airspeed.

“When we introduced flaps into the aircraft configuration, we saw more sideslip and more flow separation,” said Baughman.

With the flying portion of the project completed, the team will now focus on the data and aerial footage to identify the precise moments when the tufts on the aircraft tail indicate a change in flow characteristics.

The SPINAL TAP test management project team will present their findings to the USAF TPS in May before their graduation in early June.

Their project was certainly an interesting one,” said Vanhoy. “It was truly a blend of modern and historical approaches to flight test. I can’t wait to see how their results turn out.”

According to Major, the results of the experiment will benefit future Test Pilot School students and could possibly even spark interest into further investigation of the force change anomaly of the C-12 Huron.

“The results of the tests will definitely be folded back into the curriculum for our students. In addition, the results could lead to further inquiries if new questions are discovered during the team’s analysis,” said Major. “The broader and deeper the knowledge base of our students, the better they will perform as airborne evaluators of new or highly modified aircraft.”




All of this week's top headlines to your email every Friday.


 
 

 
afmc-q-and-a

Lean thinking, process improvement highlight Busch’s time at AFMC

During the last 16 years and six assignments in Air Force Materiel Command, Vice Commander Lt. Gen. Andrew Busch was challenged to find new methods to operate more efficiently in one of the most complex and diverse commands tha...
 
 
Air Force photograph by Bill Orndorff

3-D printing saves maintainers money at Hill

Air Force photograph by Bill Orndorff An F-16 wing attachment, molded from plastic in a 3-D printer, was used as a prototype before being machined in metal. The 309th Maintenance Support Group at Hill Air Force Base, Utah, is u...
 
 

New personal property allotment rule implemented to protect Airmen

Defense Secretary Chuck Hagel recently directed a policy change in paycheck allotments which will prohibit service members from allotting pay to buy, lease or rent personal property. The prohibition includes allotments for the purchase or finance of vehicles, such as automobiles, motorcycles and boats; appliances or household goods, such as washers, dryers and furniture; electronics...
 

 

AF realigns missions to enhance nuclear support

In response to a directive from the Secretary of the Air Force and Chief of Staff of the Air Force, the 377th Air Base Wing in Albuquerque, N.M., will report to Air Force Global Strike Command, and the Air Force Nuclear Weapons Center will reorganize, combining the AFNWC commander and Air Force Program Executive Officer...
 
 

Air Force looks at innovative acquisition processes

With new technologies rapidly coming to the forefront of the global stage, remaining the world’s greatest air force comes at an escalating cost, making responsible spending and cost-cutting initiatives high priorities for Air Force leadership. The Air Force Office of Acquisitions is partnering with industry to realize some of these initiatives and help propel the...
 
 
Air Force photograph by Rebecca Amber

Airman, screenwriter says follow your dreams

Air Force photograph by Rebecca Amber Capt. Eric Koenig, 412th Aerospace Medicine Squadron dentist, consults with a patient at the Edwards AFB Dental Office. This past Veterans Day, Capt. Eric Koenig, 412th Aerospace Medicine S...
 




0 Comments


Be the first to comment!


Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>