January - March, 2005

2005-03-28

• Put the aircraft back together and tested it in the test pit. The prerotator u-joint cross which is the weakest link in the rotor drive failed when we accidentally hit the throttle cable during an adjustment. The failure caused slight damage to a few other parts in the rotor head. We have already repaired or machined new parts, and have the aircraft back together. We plan to test in the pit again early this week. Note that the prerotator is only used on the ground to spin up the rotor, so it would not have failed in flight, nor is it a necessary system in flight. We are also running the prerotator system at a higher stress level than originally designed, since we are using a larger rotor than the original CarterCopter rotor.

  CCTD in Test Pit (Note New Rotor)

• Continued bodywork on the aircraft on the nose and starboard wing where the new ballistic chute cable was installed, and on the tail booms where they had been modified during the last flight tests.
• Installed a hydraulic cylinder and the necessary plumbing on the control stick to implement a pitch/airspeed hold, which will help hold the aircraft steady for gathering data. We are still working on the electronics and algorithms to implement the controller.

2005-03-21

• Began putting the aircraft back together in preparation for flight testing. The engine and most mechanical systems have been installed. The landing gear pump has been put back together and installed.

  Working on CCTD

• Trimmed ½" from the trailing edge of the rudders and rebalanced them. We've also installed a system to lock the rudders when the pilot engages it, in an attempt to eliminate the yaw oscillation noted in a previous update.
• Sent the ballistic parachute back to the manufacturer to perform several modifications which were necessary to increase the safety margin, since the aircraft has grown heavier since the ballistic chute was first installed. A drag ring was installed which will slow the opening of the parachute at high speeds, but speed the opening of parachute at slow speeds. The risers were swapped out with ones made of Kevlar. And a new, ½" steel cable was installed connecting the aircraft to the ballistic parachute. All of these changes increase the ultimate strength to 20,000 lbs, giving a 5 to 1 safety factor.
• Completed redoing the computer for the automatic controls. The computer has been housed in a new metal case to shield it from radio noise, and indicator lights plus a display screen have been installed on the case to aid in troubleshooting the system.

  New Auto- Controller Housing Autocontroller & Main Computer Installed in CCTD

2005-03-14

• We finished the test of the new rotor with integral spinner and droop stops. We slowly increased the rpm in 25 rpm increments, starting at 175 rpm. Once each rpm goal was obtained, the clutch was released and we immediately jammed the cyclic and pulled collective to check for any instabilities. The highest rpm we could obtain was 335 at an average rotor torque of 2425 ft-lbs for 65 seconds. We had hoped to achieve a rpm of 350, but we did not want to go over 2500 ft-lbs (83% of our 3000-ft lb proof load). The rotor was very smooth at 335 rpm. We jammed the cyclic hard several times at that rpm immediately after releasing the clutch, and there was no instability. All of this was done without a stabilizer bar (first time we have been able to do this since we had a dogleg in the 32 ft dia rotor. We felt that with the new spindle this would be possible - a model had been built and tested to confirm the design).
• Installed new radiators in the aircraft. The old radiators had been in the aircraft during the wheels up landing and in-flight fire, and had developed leaks.
• Continued work on redoing the computer for the automatic controls. Indicator lights and all external connectors have been installed on the case. Most computer boards and power supplies have been installed.
• A new video broadcast system has arrived, which will allow the ground crew to watch the video from the tail camera. The system was ground-tested with a car and performs well. We are also switching the tail camera back to the old one, which had a wider angle lens, providing a view of more of the aircraft and the landing gear.

2005-03-07

• We have completed drop testing of our next generation aircraft landing gear design, and everything worked as designed. We tested one gear to an impact velocity of 24 ft/s (1440 fpm) with a 3000 lb test weight. The drop height was 134" (107" until first impact + 27" of landing gear stroke). The landing gear did not exceed the design limits, which were themselves only 2/3 of the load applied during the static proof test. The peak decceleration during the 24 ft/s test was 5g. Depending on the weight being supported by the gear, the impact velocity could be varied accordingly, as long as the total energy being absorbed by the gear remains the same. For a 2000 lb weight, that would be an impact velocity of 30.4 ft/s (1824 fpm) and a drop height of 197". The landing gear has another noteworthy feature in that should the impact velocity in a crash be much higher than 24 ft/s, then the max pressure is kept below that which would cause yield until the gear bottoms out, which keeps the gear from failing until the max energy possible has been absorbed. The total weight of the gear, including the rim, tire, brake, and attachment hardware, but not including the pump used for retraction/extension, was less than 70 lbs. Note that these tests were for one gear supporting 3000 lbs. For a typical airplane with two main gear, this translates to a 6000 lb gross weight.

  Landing Gear Drop Test Video

• Began getting the test stand ready to test the new rotor blade with integral root fairing and droop stops. The engine has been transferred from the aircraft to the test stand. All of the collective pitch hardware has been taken off of the old rotor and put on this one, and the rotor has been put on the test stand. The rotor controls must still be added to the test stand before we are ready to test.

  New Rotor on Test Stand

• Began redoing the computer for the automatic controls. The computer will be housed in a new metal case to shield it from radio noise, and indicator lights plus a display screen will be installed on the case to aid in troubleshooting the system.

2005-02-28

• We've wrapped up this round of flight testing. We flew to 160 mph, momentarily reaching a top speed of 163 mph. We flew steadily at a mu ratio of 0.8, with peaks of 0.83. We are experiencing a yaw oscillation, however, at higher speeds, starting anywhere from 130 to 150 mph. We believe it is due to the softness of our rudder linkages and the location of the rudder aerodynamic center relative to the pivot axis. A temporary extension was added to the rudders, but did not solve the problem. We have decided to break down the aircraft and bring it back to the shop. We will test and install the new rotor with integrated spinner, which should allow the aircraft to reach a mu ratio at least 1.3 and be more streamlined. We will also use the down time to try to solve the yaw oscillation problem, as well as making several small fixes to the aircraft.

  Nice Landing Video

• On Monday, our cylinder that measures prop thrust had a failure in an internal ring that's used to hold an o-ring that seals the cylinder. We repaired the cylinder, reinforcing the way the ring is bonded so that a similar failure doesn't happen in the future. This failure kept us from flying on Tuesday and Wednesday.
• Taped up the side air scoops that were added when running with the turbo. Engine block and oil temperatures were still okay.
• On Saturday, the pilots felt the engine hiccup in flight. We will examine this issue while the aircraft is down.
• The nose gear is slowly leaking oil, probably around the seals in the pump, transferring the oil to the pilot side main gear. We will service the pump while the aircraft is down.
• Completed the new rotor with the integral root fairing and droop stops.

  Rotor with Integral Fairing

• Continued work on the mold for the rotor for the modified Monarch autogyro.
• Performed taxi and flight tests of our landing gear for the modified Monarch autogyro. There is an issue of the gear drooping too much when unloaded (in flight), and having too much lateral travel as it goes through its stroke. We plan to modify the gear, reducing its stroke, which will reduce the lateral travel and droop. Note that the lateral travel is only an issue when making zero roll landings- the tires will not slide across the pavement. When making a normal rolling landing, the tires will be able to move outward as the tire rolls. Also note that the modified gear will still have 15" of stroke- much more than most landing gear.

2005-02-21

• Repaired slip ring on the rotor that carries the flapping sensor signal.
• Found a problem with the spool valve solenoids that has been plaguing the aircraft for years, but had been misdiagnosed in the past. If a solenoid is engaged to pull the spool valve hard on in one direction, and then you immediately try to switch direction, the spool valve will lock up. So, we modified the control logic to allow a pause before trying to engage the opposite solenoid.
• Found and corrected a problem of the autocontroller boards having a different ground potential from other computer boards. This problem was probably responsible for the problems we have been having recently with the failure of autocontroller electronic components.
• Continued flight testing on Wednesday and Thursday. The weather was too bad to fly on Friday. We had several short hops down the runway, and several traffic patterns. Everything appeared to be operating properly. We plan to continue expanding the flight envelope this week.

  Nice Takeoff Video

  Nice Landing Video

  Another Nice Landing Video

• During flight testing, we were visited by both the Canadian division of the Discovery Channel, and our local newspaper, the Times Record News.
• Continued drop tests of the new landing gear design. We have now tested the landing gear to an impact velocity of 22 ft/s (drop height of 7.5 ft) with a 3000 lb test weight. We still plan to perform the tests with a 2000 lb test weight with an impact velocity of maybe 30 ft/s.

  Landing Gear Test Setup

  Landing Gear Test Video

• Worked on the new rotor blade, adding an integral spinner to the blade. The new spinner incorporates a droop stop, to keep the blades from drooping as much as the current rotor.

2005-02-14

• Continued flight testing. Last week, we flew 9 hops down the runway in 3 days of flying. Most of the time has been spent tweaking the automatic controls of the aircraft. We want to make sure everything is working properly before flying additional traffic patterns. Rotor pitch is now smooth and fully automatic from a rolling jump take-off, through unloading the rotor to a very short landing. We have decided not to perform any more zero roll take-offs and landings until we have a moveable rudder in the prop slipstream and have broken the "Mu 1 barrier".
• Repaired a board that generates an oscillating signal used to pulse the solenoids to give fine adjustment of the automatic controls.
• Straigtened the suction line to the hydraulic boost pump. It would crimp under certain conditions, reducing the flow to one of the pumps which drives the automatic controls.
• Serviced the prerotator clutch cylinder, which had been sticking, causing erratic engagement of the prerotator.
• Removed the high volume boost by-pass solenoid valve, so that both hydraulic pumps are now full-time.
• Corrected loose connections in the autocontroller board, which were causing a good deal of radio static.
• Continued drop tests of the new landing gear design. We have now tested one gear at a 20 ft/s impact velocity (drop height of 6.2 ft) at a test weight of 3000 lbs. Peak cylinder pressure was only 2160 psi. Maximum design pressure is 2700 psi, so there is capacity to increase either the weight or impact velocity. We also plan to perform the tests with a 2000 lb test weight with an impact velocity of maybe 30 ft/s. Note that the landing gear system was statically tested to 4000 psi.

  Landing Gear Test Fixture at 3000 lb Test Weight

• Worked on the new rotor blade, adding an integral spinner to the blade.

  Rotor with Integral Spinner Partially Completed

2005-02-07

• Due to bad weather, we were not able to fly on Monday, Tuesday, or Wednesday. This gave us some time to catch up somewhat on engineering projects and administrative responsibilities.
• Performed several drop tests of the new landing gear design. We dropped 3000 lbs at an impact velocity of 14 ft/sec, and everything is looking good so far. We plan on going up to a 20 ft/s impact velocity with the same weight, and 25 ft/s with a 2000 lb load. Note that these tests are for one gear only. For a typical aircraft with two main gear, these loads translate to 6000 lb and 4000 lb gross weights, respectively.
• Starting on Thursday, we flew several more short hops down the runway. After the first hop, there was a low oil pressure warning, and the pilots shut down immediately. The harmonic balancer had come off of the engine, allowing oil to leak, and taking both alternator belts with it. The alternator belts also drive the water pump, so the engine block temperature started to rise. It looks like the pilots shut down quickly enough to avoid damaging the engine. We reattached everything, and tightened the harmonic balancer much tighter than the shop that put the engine together.
• On several of the early flights, the engine wasn't making nearly as much power as expected, and exhaust temperatures were very low. It appears to have been caused by the wideband oxygen sensors not working properly. The simple fix is to cycle the power to the sensors once the engine is running to reset them. We also tweaked the programming of the electronics that convert the wideband oxygen sensor signal to a signal that the engine computer can use, making the engine run at a more constant air fuel ratio without hunting.
• Worked on the board that mixes the flapping sensor signal and the stick position signal, to remove stick movement from the flapping reading. It appears that we have it just about right.
• Changed the primary comm radio in the aircraft. We are getting static at the unicom frequency of 122.8 that doesn't show up on other frequencies. It appears that something in the aircraft is causing that static. We are looking for the source.
• Made numerous other changes to the electronics to tweak the automatic controls of the aircraft.

2005-01-31

• The engine that suffered the power drop the previous week was damaged due to high temperatures and pressures caused by pre-ignition. Even though our EGTs appeared fine, because of the high compression ratio, the peak temperatures were high, but produced lower exhaust temperatures than for a normal compression at a given fuel-air ratio. The high pressure and heat deformed the valves, accounting for the low test compression in 5 of the 8 cylinders. We also determined that we were not running with "cold" enough spark plugs, which caused the electrode tip to glow red hot and cause the pre-ignition. We replaced the engine, installed colder plugs and wide band oxygen sensors with appropriate circuitry to run the engine at a richer air-fuel ratio to cool the combustion temperatures. However, upon starting the new engine, it did not have any oil pressure. The company that built it had left out a galley plug. We pulled the engine again, let the company repair it, and re-installed it back into the aircraft on Wednesday night.
• The television news program, 60 Minutes, came to Olney for a story on the future of aviation that will air sometime in the upcoming months. Bob Simon was the correspondent covering the story, and interviewed company president, Jay Carter, on Thursday. Thanks to a lot of hard work from our technicians and several long nights, the aircraft was ready to fly on Friday, with a camera crew from 60 Minutes there to film it. Because of weather, we were only able to fly two short hops down the runway, and another short hop on Saturday for our annual shareholder's meeting. Low ceilings prevented any longer flights.

  Camera Equipment in the Hangar

• All systems appear to be functioning correctly. Before flying, we ran a static full throttle run for 3 minutes on the replaced engine, until high oil temperature reduced the oil pressure below our minimum of 45 psi (there was no airflow to aid in cooling). Engine horsepower was 380 with a static thrust of 1850 lbs. In flight at 90 mph, the full throttle horsepower increased to about 400 due to ram air, and the increased airflow kept the oil at an acceptable temperature.
• We have still not determined exactly what is causing the erroneous horsepower reading noted last week, but it appears to be related to the vertical acceleration at liftoff.

2005-01-24

• Continued test flying in Olney. We have now flown several traffic patterns in addition to continued short hops down the runway. The systems we have checked appear to be working well. The next items to check are the landing gear and the auto rotor rpm control as we fly between 30 and 140 mph. Our new scimitar propeller provides about 500 lbs more thrust than the previous prop, even with 50 less horsepower, which allows the aircraft to accelerate to about 90 mph and climb to 300 ft by the 2500 ft marker. The pilots commented that the aircraft is very smooth and flying better than ever.

  Aircraft in Flight

• During one traffic pattern, we had a problem of losing horsepower while the pilots were on downwind. The pilots landed without incident. Examining the aircraft after the flight, we found that the O2 sensors were not tight, which could have affected their readings and caused the loss of power. All of the spark plugs looked fine, except one which had some residue. We tightened the O2 sensors, replaced the spark plugs, and ran again. We had a power loss on a subsequent pattern flight as well. This occured at a lower altitude, but the pilots were still able to land without incident. After this flight, examination of the spark plugs showed that the tips had been burnt off of five of them. We are currently investigating what could have caused the power loss, and will not attempt another pattern flight until the problem is corrected.
• We are having a problem of what appears to be an erroneous horsepower reading when collective is above 6-7º. Even though the horsepower reading drops off, the thrust reading stays high, indicating that horsepower is higher than what's being measured. We will investigate this problem this week as well. We suspect an interference somewhere with the collective cable linkage which pushes against the engine and affects the engine torque sensor.
• Corrected a compression crack in one of the tail booms. On one of the short hops down the runway, too much collective on flare caused the aircraft to pitch up, allowing the tail booms to hit hard before the landing gear. We believe the structure was weakened in that area when heat was applied to debond and relocate the boom training wheels. The crack was easy to repair, and both booms were reinforced before additional flights resumed the next morning.

2005-01-19

• We apologize for the delay from our usual Monday update. The webmaster has been very busy with several projects.
• We are back Flight Testing in Olney! We have performed several pitch captures and short hops down the runway to test all the aircraft systems to make sure they're working properly. We have made many changes to the aircraft since the last flight tests. Some of the most notable changes include removing the turbo, installing the new scimitar propeller & spinner, overhauling the electronics & installing the computers in one main case, and changing the hydraulic system to be driven by the rotor, instead of engine oil pressure. We were able to remove 175 lbs of nose ballast weight, so that the aircraft test weight with both pilots, 30 gal of fuel and the ballastic chute, is now 3800 lbs.
• The pilots have reported the aircraft has never flow so well. Initial acceleration is fantastic.

  Aircraft in Olney

  Aircraft in Flight

• Before taking the aircraft to Olney, we completed all of the small projects including calibrations, bleeding lines, etc. to ready the aircraft for flight testing, ran several landing gear retraction tests in the shop, and ran the aircraft in the pit for a final systems check to ensure that the engine and all rotating hardware were operating properly.

2005-01-10

• Completed prop mapping in the test pit. The pitch vs rpm has been optimized, but the engine is not producing as much power as expected. We will try to correct the power problem this week, and will see if we need to re-map the propeller.
• Installed the rotor on the aircraft.
• Tested the landing gear retraction. It took longer than we would like. We are going to switch to a less viscous hydraulic fluid, and perform the test again.

  Aircraft Ready for Landing Gear Retraction Test

• Ran the aircraft in the test pit with the rotor, and tested all systems. The new rotor flapping sensor appears to be functioning properly. We are going to switch to a less viscous hydraulic fluid for the aircraft hydraulics (the same as being used for the landing gear).

2005-01-03

• Continued testing in the test pit. Partially completed mapping the propeller- determining the optimum pitch vs. rpm and power. The data that we have gotten so far shows lower thrust values than what we were getting on the test stand. Two possible causes for this are 1) the pressure gauges used on the test stand were out of calibration and 2) the engine support may have been in a bind such that when a load was placed on the rubber mount due to torque, it caused a thrust component that added to the measured prop thrust (when the engine was installed back into the aircraft, we did notice that one of the mounts was in a bind).
• During propeller mapping, the main drive belt failed. The belt tensioner was not tight enough, which allowed the belt to slip off of the pulley cogs. As this happened, the mechanical advantage on the belt teeth became great enough to fail the belt due to the high tension. We think this high tension also damaged the engine, causing metal to metal contact on one of the main bearings. After replacing the belt, we ran the engine again, and after only a little while the main bearing spun. We replaced the engine and the aircraft is mechanically ready to go into the pit again.
• Continued work debugging the new electronics.
• Continued work on moving the "training" wheels further forward on the tail booms to give more prop clearance. Both wheels have been moved, and the fairings have been installed. There is still some finishing work to do before painting.

  Relocated Training Wheel

• During testing in the pit, we noticed that the prerotator shaft was bent. We do not know exactly when this happened, but think the most probable time was when the prerotator yoke failed in March of last year. We replaced the bent part.
• Finished one half of the mold for the rotor for the modified Monarch autogyro and future Personal Air Vehicles. Flipped the plug and mold in preparation for making the other half.

  Modified Monarch / PAV Rotor Mold