April - June, 2005

2005-06-27

• This item was listed in last week's update, but was such an important event for our company, that it's being repeated this week. During routine testing on the morning of Friday June 17th, the CarterCopter achieved a mu of 1! During the second half of the flight, the pilot, Larry Neal, controlled spindle trim manually (the way rotor rpm is controlled in high speed flight), in stages gradually increasing airspeed and slowing rpm. With all of the other automatic controls working well, the rotor rpm was the only parameter the pilots had to monitor closely, so we were comfortable flying to high mu ratios this way. Since everything was looking good and the aircraft was flying smoothly, the pilot allowed the rotor rpm to decrease to 107 rpm at 170 mph, reaching mu 1. Following our cautious approach of only expanding the envelope a little bit each flight, the pilot quickly slowed back to a lower mu ratio. The pilots reported that at mu-1, and during the portion of the flight leading up to that point, the aircraft was flying smoothly and the rotor was stable. There was no cabin hop, and the rotor stayed in track the whole time. The aircraft flew continuously at a mu ratio of 0.9 or greater for 20 seconds. Brad King was co-pilot for the flight. The first part of the flight was spent testing the automatic spindle trim controller, which worked well, but still requires some tweaking.

  CCTD Mu-1 Flight Video The Crew on the Day of the Historic Flight Strip Chart Recording of Flight Data

  Although we did not take off with the intention of breaking mu-1 on that flight, from as well as the aircraft had been flying and with the way we had been expanding the envelope during the week, we knew there was a pretty good chance that we would break mu-1 that day. The fact that it occurred on the first flight of the day was a pleasant surprise. Two former Bell engineers were present to witness the event, and one employee had even brought in champagne.
  
  Only time can tell, but we feel this flight was a milestone in aviation history. Efficient high speed flight with vertical takeoff and landing has long been a major goal throughout the history of flight. By flying stably at mu-1, the CarterCopter has demonstrated what some critics have said was impossible, showing that the slowed rotor concept is valid and achievable, and has pioneered the the way for future aircraft to take advantage of this technology.
   
• Continued work on the mold for the propeller for our modified Monarch autogyro. The prop is designed for the 62 HP Rotax 582 engine.
• Worked on the rotor head for the modified Monarch autogyro. This rotor head will give the blades two pitch settings - flat for prerotation, and some increased pitch for in-flight. This two-pitch setting will allow the autogyro to perform jump takeoffs.
• Regarding the damage to the aircraft that occured last week, our engineers have not yet had a chance to study the aircraft. We spent the entire week working on a proposal that was due today. We will give more details of the incident once we have had a chance to study the aircraft.

2005-06-20

• During routine testing on Friday morning, the CarterCopter achieved a mu of 1! During the second half of the flight, the pilot, Larry Neal, controlled spindle trim manually (the way rotor rpm is controlled in high speed flight), in stages gradually increasing airspeed and slowing rpm. With all of the other automatic controls working well, the rotor rpm was the only parameter the pilots had to monitor closely, so we were comfortable flying to high mu ratios this way. Since everything was looking good and the aircraft was flying smoothly, the pilot allowed the rotor rpm to decrease to 107 rpm at 170 mph, reaching mu 1. Following our cautious approach of only expanding the envelope a little bit each flight, the pilot quickly slowed back to a lower mu ratio. The pilots reported that at mu-1, and during the portion of the flight leading up to that point, the aircraft was flying smoothly and the rotor was stable. There was no cabin hop, and the rotor stayed in track the whole time. The aircraft flew continuously at a mu ratio of 0.9 or greater for 20 seconds. Brad King was co-pilot for the flight. The first part of the flight was spent testing the automatic spindle trim controller, which worked well, but still requires some tweaking.

  CCTD Mu-1 Flight Video The Crew on the Day of the Historic Flight Strip Chart Recording of Flight Data

  Although we did not take off with the intention of breaking mu-1 on that flight, from as well as the aircraft had been flying and with the way we had been expanding the envelope during the week, we knew there was a pretty good chance that we would break mu-1 that day. The fact that it occurred on the first flight of the day was a pleasant surprise. Two former Bell engineers were present to witness the event, and one employee had even brought in champagne.
  
  Only time can tell, but we feel this flight was a milestone in aviation history. Efficient high speed flight with vertical takeoff and landing has long been a major goal throughout the history of flight. By flying stably at mu-1, the CarterCopter has demonstrated what some critics have said was impossible, showing that the slowed rotor concept is valid and achievable, and has pioneered the the way for future aircraft to take advantage of this technology.
   
• During a subsequent flight, the pilots executed a forced landing in a nearby field. The pilots walked away from the landing unharmed, but the aircraft sustained significant damage. The exact cause of the failure is still being investigated, but is not in any way related to the high mu ratio on the previous flight.

2005-06-13

• Worked on the automatic controller for spindle trim, which will allow us to hold a target rotor rpm as the aircraft speeds up and unloads the rotor. We did much of the development and testing using the X-Plane Flight Simulator in conjunction with a separate computer to simulate the CarterCopter's computers and automatic controls. With a few modifications to the original algorithm, we were able to develop a system that was stable on the simulator. We have not had a chance to test it on the aircraft, yet.
• Installed new alternators with twice the capacity of our previous alternators, and replaced the old 5 amp alternator circuit breakers with 10 amp circuit breakers. We flew one short hop down the runway on Friday, in which we discovered that the new alternators would require even higher amperage circuit breakers. Along with that change, we decided to run heavier gauge wires to handle the higher capacity.
• Continued work on the mold for our new propeller to go on our modified Butterfly autogyro, which is designed for the 62 HP Rotax 582 engine.

2005-06-06

• Continued flight testing in Olney. Overcast and foggy weather during much of the week kept us from flying as much as we'd like to. We continued our approach as described in last week's update, where each flight we limit our top speed to 10 mph faster than the max speed achieved on the previous flight. In this way, we've gotten up to 160 mph, momentarily reaching 162 mph. In one flight, we flew at a mu ratio of 0.7 or greater for eight seconds, peaking out at 0.74. Our focus now is tweaking the automatic control for our spindle trim, which will allow us to hold a target rotor rpm as the aircraft speeds up and unloads the rotor. We must get that system working before flying to higher speeds.

  CCTD in the Air CCTD in the Air

• During one flight, one of the rod end bearings for our new overhung pulley load support bracket failed. Although the rod end was rated for high loads, there was a grease sert right in the high stress area of the part, which is where the failure occured. Since the piston for the bracket is pressurized from our engine torque sensor, when the rod end failed, it allowed the torque sensor piston to bottom out, giving a zero torque reading, and thus a zero horsepower reading to our prop pitch controller. Since that controller tries to hold an rpm based off of the horsepower reading, when the horsepower reading went to zero, the controller increased prop pitch to its maximum, trying to slow down the engine rpm. This bogged down the engine, and combined with the stalled angle of attack, caused a drastic loss of thrust, which the pilots interpreted as a problem with the motor. They throttled back to zero, and made a non-event power off landing. The actual problem was not diagnosed until after the aircraft was on the ground, or the pilots could have changed the prop controller to a different mode, holding a reasonable rpm independent of horsepower. We replaced the rod end bearing with a different type without a grease sert in the high stress area, and continued flying.

2005-05-30

• We're back in Olney flight testing. We've made several short hops down the runway as shake-down flights, as well as several traffic patterns. Our longest flights were on Friday, with one flight lasting 16 minutes, and two flights lasting over 20 minutes. Since we are using a new rotor, we are limiting the pilots to a top speed each flight of 10 mph faster than the previous flight. Everything appears to be working properly while we're making the tweaks necessary to expand the envelope. On our second to last flight on Friday, we reached a top speed of 156 mph, and a peak mu of 0.63. The mu ratio was continuously at 0.6 or higher for 20 seconds. A low ceiling prevented us from expanding the envelope any further that day. Our new rudder locking system seems to have eliminated the yaw oscillation that occured at high speeds during our previous flight tests, as noted in the February 28th update.

  Aircraft Taking Off Aircraft Taxiing Aircraft Taxiing

• Before going to Olney, made several changes to the fuel system: put new, larger, fuel filter on discharge side of fuel pumps, removing filter from suction side; replaced fuel regulator; increased suction tube in tank from 1/2" to 5/8" diameter; added sight gauge to fuel tank.
• On the new propeller to go on our modified Butterfly autogyro, we test fit the interior layers of each half of the mold, and they go together perfectly.

2005-05-23

• We fabricated and installed the new bracket to support the overhung load on the engine. The big problem before had always been to get a support bearing to just counter the belt load and not add to the load when this new bearing support structure moved due to temperature changes - iit would only take a few thousands of an inch growth for the bracket to add to the load. We already had a system in place, where in order to measure engine torque, the engine was supported on an arm with a pivot on one end, and a cylinder with a pressure sensor on the other end. We used this pressure to feed a piston on our new support bracket, so that the force it applies is always proportional to the actual engine torque, and in turn the belt tension.
• Reinstalled all other components back into the aircraft. We will take the aircraft back to Olney for flight testing this week.
• Began work on a new propeller to go on our modified Butterfly autogyro, which was designed for the 62 HP Rotax 582 engine. The plugs have been completed, and the interior layers of the molds laid up and test fit to each other. For this propeller, for the first time on any of our props, we sent a 3D computer file to a machinist, and using a 5-axis CNC mill, they were able to make 2 separate plugs for us, one for the top half of the prop, and the other for the bottom half. Previously, we had made a plug for the entire propeller by hand, and then built a skirt around that before making the molds for the top and bottom halves. This new method saved us weeks of labor.

  Prop Plugs as sent by Machinist Prop Plugs after Surface Prep & Finishing Test Fitting Prop Mold Upper & Lower Halves

• Continued work on the software portion of our airspeed hold controller. Toby Landes, who has designed most of the hardware and software for the CarterCopter control systems and data collection systems came down on Saturday, and spent the better part of the day working on this software. There is still some work remaining, but the bulk of the work was completed over the weekend.

2005-05-16

• Continued flight testing in Olney. Flew several more short hops down the runway as shake-down flights to make sure everything was working properly, as well as a few traffic patterns. Unfortunately, late Wednesday afternoon we lost engine oil pressure just after a 30 mph rolling jump takeoff and then made a non event landing. The loss of oil pressure appears to be due to a spun main bearing. This is the third time we have had this type of failure. There were other contributing factors in the first two failures, but now it seems apparent that the cause is the overhung load on the engine crank coming from our drive pulley, which is especially bad during prerotation when the engine's at high torque and low rpm. We have already designed a support bracket, which must be fabricated and installed before we can fly again.
• By flying early Wednesday morning when the air was still calm, we were able to confirm that the new rotor with integrated root fairing is stable (flying when it was gustier or when there was more turbulence, the pilot was unable to tell if the aircraft behavior he felt was due to the rotor or due to weather).
• By increasing the collective to a slightly higher pitch with each successive takeoff, we were able to go to 11º of collective (2º higher than what had been our normal), which caused the aircraft to jump 35' into the air in a 30 mph rolling takeoff. Data from these flights indicates that we could probably go to 12º, at which point we will begin reducing the takeoff speed, until we are performing jump takeoffs, or have achieved the minimum speed at which the pilots are comfortable.

  Rolling Takeoff with 11º Collective Pitch Another Rolling Takeoff with 11º Collective Pitch

• Continued work on updating the flight simulator.

2005-05-09

• Took the aircraft to Olney to continue flight testing. We've flown several short hops down the runway as shake-down flights to make sure everything is working properly. The new rotor appears to be doing well. We have added 4 lb. lead weights to each of the corners of the root fairing (16 lbs. total) to act as a stabilizer bar for the rotor.

  Aircraft in Olney

• Replaced the cylinder to operate the stick for the pitch/airspeed hold with a larger cylinder. Continued work on the logic for the controller.
• Continued work on updating the flight simulator.

2005-05-02

• Spent much of the week tracking down a hard to diagnose electronics problem. It turned out to be a strain gauge to measure collective cable force. When high torque was applied to the rotor, the resulting movement on the rotor gearbox caused the strain gauge to short out.
• Completed a new rotor mold. By adding or removing sections, this mold will be able to produce rotors ranging in diameter from 20' to 34', including the rotor for our 2-Place PAV, 4-Place PAV, and the Butterfly autogyro that we are modifying with Carter technology.

  PAV Rotor Mold

• Began work on the electronics for a pitch/airspeed hold, which will help hold the aircraft steady for gathering data.
• Continued work on updating the flight simulator.

2005-04-25

• Carter would like to recognize our web hosting company, Web Fire Communications for working with us in preparation for the increased web traffic from the two television shows last week.
• Finished repairing the rotor.
• Put the aircraft back together and tested it in the test pit. Everything appeared to be functioning properly.

  Testing in the Pit

• The CV-joint which transmits power to the prerotator failed due to wear and was replaced.
• Installed a pressure sensor in the landing gear, which will allow us to monitor the pressure during landings.
• Installed fuses and other circuitry to protect the autocontroller from power surges and spikes.
• Continued work on updating the flight simulator.

2005-04-18

• The CarterCopter was on two television programs this past weekend, Discoveries This Week on The Science Channel, and 60 Minutes on CBS. Video of the Science Channel story is available by following the link below, while the 60 Minutes story can be read at Full Print Story on 60 Minutes
  

  Video on Discovery Channel

• Carter would like to recognize our web hosting company, Web Fire Communications for working with us in preparation for the increased web traffic from the two television shows mentioned above.
• Continued work on repairing the rotor. All of the composite work is now done. We're currently making lead weights, molded to fit snugly into the root fairing, to have them ready to go if we find during flight testing that they're needed to stabilize the rotor.

  Repairing Rotor

• Finished tweaking the landing gear on the test stand. It's ready to go back into the aircraft.
• Began replacing all light bulbs in the cockpit with LEDs.
• Continued work on updating the flight simulator. We've installed a hydraulic system that will be able to automatically move the collective control as in the actual aircraft. We've purchased a new, more powerful computer, onto which we're installing the latest version of X-Plane. We're writing a plug-in for X-Plane, which will simulate our main display (allowing us to update the simulator at the same time as we update the aircraft), as well as simulate our automatic controls, including sending a signal to the controller that will control the collective hydraulics. These changes will make the simulator a better training tool for our pilots.

2005-04-11

• For those of you who remember reading that a 60 Minutes film crew had visited us in January, the story is finally ready to air. It will be shown this Sunday, April 17th, at 7:00 pm ET/PT on CBS. The aircraft will be one of those included in a segment titled "Highway in the Sky," exploring the future of aviation. The CarterCopter will also be on the program, Discoveries This Week, airing this Friday, April 15th, at 8:00 pm ET on The Science Channel. Encore presentations will be shown throughout the weekend. For a complete list of show times, check your local listings, or look on The Science Channel's website. And for those of you in our local Wichita Falls area, look for a newspaper article featuring Carter in the Sunday edition of the Times Record News.
• Company president, Jay Carter, will be present at the Sun 'n Fun Fly-In in Lakeland, Florida this weekend. He will present two forums, one on Friday the 16th at 1:00 pm, and another on Saturday, also at 1:00 pm.
• Began work on repairing the rotor. The old root fairing has been removed, a new root fairing has been layed up, and the composite blade root pivot bracket attachment point has been straightened. Remaining work includes reinfocing the blade root with unidirectional carbon fiber, reattaching the pivot bracket, and installing the new root fairing. This new root fairing is still going to be integral to the blade, but is not going to include a droop stop.

  Repairing Rotor New Rotor Fairing

• Removed the main landing gear from the CarterCopter, and began modifying the new landing gear test stand to accomodate them. We plan to tweak these gear using lessons learned in testing our new, larger gear.
• Spent some time optimizing the antennae for transmitting and receiving the tail camera video from the aircraft to the ground. With the transmitting antenna mounted on the belly of the aircraft to be optimized for flight, reception with the aircraft on the ground is poor when line of sight is obscured by obstacles and even parts of the aircraft itself.
• Installed a new board into the main computer case, which will test the computers and electronics to aid in diagnosis when there is a problem. It will not operate the entire time the aircraft computers are on, but instead can be turned on independently.

2005-04-04

• Got the aircraft back together and into the test pit. All systems worked properly.

  CCTD in Test Pit

• Performed two high speed taxis and one short flight on Friday. There were two intermittent electrical problems that gave us problems throughout the day that had to be diagnosed and repaired, one related to the flapping sensor and the other related to the engine fuel-air controller. We also had a problem with a piece of o-ring plugging up one of the brake line locks, keeping that brake from operating. However, we were able to get all of the problems corrected.
• During the flight on Friday, the pilot commented that although the rotor was very smooth and still controllable, it seemed to have a mind of its own. This may have been due to the fact that we removed all of the gyroscopic stability with the removal of the stabilizer bar, so we decided to add stabilizer weights to the root fairing- one weight in each of the four corners of the root fairing, totalling about 1/5 of the weight that we flew with the last time. We only had two heaters, so we tried heating up the entire fairing to cure the resin bonding the weights at all 4 locations at the same time. We failed to consider the 1200 lbs of spring force on the toggle springs used to reduce the collective load, which caused the composite blade root pivot bracket attachment point to twist/creep excessively at the elevated curing temperature , and also distorted the spinner so that the 2 spinner halves would not align. It will take about a week and a half to make the repairs and replace the spinner, which means that the CarterCopter will not make it to the Sun 'n Fun fly-in in Lakeland, Florida. Since our chief test pilot, Larry Neal, will be attending the fly-in to represent his own company, we will not be able to fly until after he gets back, about two and a half weeks from now. We will use this down time not only to repair the rotor, but to concentrate on a few other projects, and to make a few modifications to the aircraft, most notably modifying the brakes to prevent a similar failure as to what happened last week, and modifying the landing gear using lessons learned in testing our new, larger gear.
• Company president, Jay Carter, will be present at the Sun 'n Fun Fly-In in Lakeland, Florida. He will present two forums, one on Friday the 16th on Personal Air Vehicles (PAVs), and another that Saturday on the quiet efficient Scimitar prop and the extreme energy absorbing landing gear. There will also be a Carter Aviation Technologies press conference on Saturday morning. (This press conference has been cancelled.)