|
|
Hover mouse over any thumbnail to view larger image - more info on all concepts
Carter Aviation Technologies is a research and development company, pioneering new aviation concepts. Our primary focus is the slowed-rotor compound aircraft, a vertical takeoff and landing aircraft that uses the rotor for takeoff and landing, and a small, efficient wing for high speed flight, up to 500 mph, all with much less complexity than a tilt-rotor or other vectored thrust vehicle. We successfully demonstrated the slowed rotor concept with the CarterCopter Technology Demonstrator (CCTD), the first and only aircraft to reach mu-1 ( more info).
License Agreement with AAI
Carter Aviation Technologies LLC (Carter) of Wichita Falls, TX is announcing that they have completed negotiations with AAI Corporation, an operating unit of Textron Systems, a Textron Inc. company, of Hunt Valley, MD on an exclusive licensing agreement for Unmanned Aircraft Systems (UAS) using Carter's revolutionary Slowed Rotor/Compound (SR/C) Aircraft Technology - a combination of rotorcraft and fixed-wing aerodynamics. The 40-year exclusive agreement covers all UAS programs worldwide.
For more information, read the full press release:
2009-11-17 Carter Signs UAS License Agreement with AAI
This Month at Carter
2009-11-02
- We are creating two new spinoff companies - one for manufacturing which will initially build kit aircraft and military UAVs, and one for development and prototyping (more info). This is an opportunity to be involved with slowed rotor compound aircraft. If interested, please visit our Employment Opportunities page.
- Continued work on the 4-Place PAV Prototype.
- Continued with the wiring. Wiring for most major systems is now complete.
- Continued work on the baffling system.
- Continued work on the new tilting mast. Ribs and other internal components have been completed and installed. The two halves must still be bonded together.
- Began modifying the tip of the rotor blade mold. The new shape makes the transition more gradual from the constant chord section to the increased chord at the tip.
- Completed laying up a short section of the rotor skin, machined the skins as necessary, and began a proof test. We decided to test the skin independently of the spar, so that the strength of each can be determined. On one end of the skin is the pin joint that is laid up exactly as we plan to attach the skin to the spar. To pull on the skin, we need another pin joint, but because of constraints of the test fixture, we couldn't build up that joint in the same manner. We laid up as much titanium inside the mold as we could, machined away what was required to fit in the test fixture, and then added doubler material to the outside of the skin after the primary cure. After 4097 cycles at 240,000 lbs, this doubler delaminated from the skins. Fortunately, the reduced titanium inside the skins was still able to carry the load. We've re-attached the doubler in a modified manner that should reduce its stress concentration factor, and have resumed the test. Once we reach 10,000 cycles, we plan to slowly increase the load to 360,000 lbs and perform 1,000 cycles at that load. If the skins pass those 1,000 cycles, we will slowly increase the load until the part fails or we reach the limit of our test fixture.
For reference, these proof test loads are based on 160k lbs of centrifugal force from the rotor at 400 rpm (the max jump takeoff rpm). 240k lbs is a 1.5x safety factor under the cyclic loading, and 360k lbs is a 2.25x safety factor for static loading.
- Bonded together the two halves of the new spar, machined as required, and performed the proof test. We had the same plan for the spar proof test as that described above for the skins. On our first attempt at loading the spar, we delaminated the spar along the centerline at 200,000 lbs. This was due to the angle of the unidirectional carbon in the region where the thickness increases in the transition from the spar caps to the titanium lug. The spar was repaired and circumferential windings added in the appropriate location to address this problem.
After the repair, we resumed testing of the spar. We successfully completed 10,000 cycles at 240,000 lbs. As we began slowly increasing the load for the next phase of testing, we heard some popping at 300,000 lbs and paused. At first, the popping stopped immediately after we paused, but after several seconds of silence, the spar failed. On inspection, it appears that the failure was in the circumferential windings where the two spar caps come together (not the circumferential windings that were added as described above).
We do have plans to improve the spar design, and we do plan to build and test another spar. But to put the achieved load into perspective, as mentioned above, the load on the spar will be around 160k lbs at 400 rpm. We would have to spin the rotor at 550 rpm to put 300k lbs of load on the spar. To look at it another way, if we only spin the rotor to 365 rpm, we'll only have 133k lbs of load on the rotor, which will let us operate with the same 2.25x safety factor that was our original target.
- Completed modifying the spar mold. The spar for the test described above was laid up in two halves and bonded together. The new mole will allow the spar to be laid up and cured in one operation.
Modifying Plug
for New Blade Tip
Left Half of
Tilting Mast
Upper Skin for
Proof Test
Installing Spar
for Proof Test
|
New Updates on the First Monday of Every Month, Workload Permitting
Archive of Monthly Updates
This web site was last updated on 2009-11-02.
|
Home
