View Full Version : Flying trailer
07-16-2007, 10:26 AM
My friend Xavier Averso sent me this video of Michael Obermaier, designer of the DF 02, of a test performed on a 900 kg trailer (1800 lbs).
If you never saw a flying trailer, it's worth watching the video.
07-16-2007, 03:45 PM
Also a shorter version is on youtube:
One more reason to remove the rotor blades when towing your gyro on a trailer. :D
07-17-2007, 06:25 AM
Yeah, but what a smooth ride you'd get from the trailer...
07-17-2007, 10:23 AM
That is funny, The new "heavy lifting" gyro! Or else it is a featherlight trailer!
Do you think I'd get better gas milage on the truck if I leave my blades on the gyro next time I haul it to a fly in?
07-17-2007, 10:52 AM
I'm going to send the link to the guys at featherlite trailers just to see what they say...
Cool, I didn't realize this is how a lot of testing got done! I can see it getting interesting back in my hometown, we got like a two-mile stretch of straight road going across the valley bottom.
Please be careful with such things, Tom Milton told me that a friend of him was killed making such a test. I don't want to feel responsible for accidents.
-> may you all have safe landings - even with your car trailer :rolleyes:
07-18-2007, 05:48 AM
DOn't worry, I was just joking.
07-18-2007, 02:03 PM
Before the advent of two-place powered gyros, one way to learn to fly gyros was in the Bensen "flying trailer," a/k/a the boom trainer.
It had no separate trailer strapped on below; the gyro itself was the trailer. It was fitted with a long trailer tongue in place of the nosewheel. At the front end of the tongue was the usual car hitch. It had an extra-wide main axle and castering main wheels linked by a tie rod to prevent damage from crabby landings.
There are probably a few of these units still around. Craig Wall was training people in one in Texas up to a few years ago.
07-18-2007, 05:08 PM
Actually there are several boomtrainers scattered around the U.S. PRA Chapter 62 has a functional one and there is at least one more in Texas that was being built.
I've attached a picture of Craig Wall's that several of us had a chance to experience before Chapter 62's was built. Craig towed it from Hondo (West of San Antonio) to Houston so that we could try it out. Subsequently some of us went to Hondo and trained with Craig.
Both Craig's and Chapter 62's are built from mild steel so that they could be towed on the highway. Chapter 62 incorporated a very simple roll bar in their's.
You can see a C. Wall innovation in the picture and that is a 3rd wheel that is used when Craig starts training. Craig gives minimal instruction since he thinks one of the benefits of the boomtrainer experience is that the student is learning to be a test pilot and recognize when to back out of a situation.
He breaks his training down to the smallest steps possible so by using the 3rd wheel the student learns to 1st control the machine in the roll axis only while learning blade management and balancing on the wheel. Then the wheel is taken off and the rest of the training procedes.
You will notice that Craig did not use castoring wheels. Chapter 62 incorporated removeable castoring wheels and tie rod.
Chapter 62's most recent pilot had considerable fixed wing flying time before he learned to fly a gyro and swears that the reason it didn't take him very long to learn how to fly a gyro is because of learning blade management on the boomtrainer.
The boomtrainer doesn't take as much real estate to fly in as a gyroglider but still requires someplace that will let an auto operate. Craig Wall feels that a boomtrainer will provide 90% of the experience that a glider will provide while being less prone to upsets.
In addition to the standard boomtrainer, Chapter 62 built, but has not tested, a 'on the trailer' boomtrainer. The trainer is tethered on top of a trailer and has devices to limit flight travel in all directions or to limit it in only one direction. While the boomtrainer is relatively safe, one Chapter 62 incident caused the 'on the trailer' trainer to be built since it was felt there was even more control of the student pilots action. Even though the 'on the trailer' trainer doesn't pickup the trailer, the subject of this thread isn't a new concept.
07-19-2007, 05:27 AM
One of the things that amazes me about this test is how little coning of the rotorblades that there is. I would have thought that at 3g's there would have been a lot more.
07-19-2007, 05:38 AM
The steady-state coning angle doesn't change with changes in gross weight.
Lift varies as the square of airspeed. A rotor blade's RPM is its airspeed. Therefore, lift varies as the square of RPM
Centrifugal force also varies as the square of RPM.
Coning angle is the angle whose tangent is the ratio (lift per blade)/(centrifugal force per blade). This ratio stays constant as rotor load goes up. So the coning angle stays constant.
Coning angle does increase momentarily when you suddenly pull G's. Once the RRPM catches up to the higher load, coning angle goes back to it usual value.
Coning angle changes with changes in collective pitch, since this alters the rotor's RPM for a given lift.
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