I'm pretty sure I've posted Chapter 62's experience with the boomtrainer but I can't find it in this thread. So, I'll do it again!
This post will cover several replies I could have made in this thread.
First the boomtrainer has hazards of its own. It can be rolled! Chapter 62 managed to do it because of an untrained tow team and a good gyro pilot that made a bad decision. Without going into detail (I know it is on the Forum some where!) the boomtrainer landed off to one side and without our castering wheels installed, it twisted the boom and rolled over. The very simple roll bar kept the one injury to road rash on one arm of the pilot. After thinking about it I don't believe castering wheels are a good idea, particularly if the tow driver puts the trainer on the ground off to one side which is what happened in the Chapter 62 roll over incident.
The boomtrainer
is pitch limited and also yaw limited but not as much in yaw as pitch. You can achieve a pretty severe yaw angle! But I don't think it is a good idea to check out the limits since it really doesn't serve any training purpose that I can see. Craig Wall, who probably has more boomtrainer experience that anyone here could give more insight.
The last email address I have for Craig is
[email protected] Don't be put off if you get an email back saying you are an idiot! That is just the way he is! He doesn't do it to all of us all the time and it is usually when something out of the norm is suggested.
I can't tell exactly what Larry has done with the boom but if he has added a flex joint or two where the trainer can climb level without the tow hitch interfering and also use the roll axis along with a rudder then all three control axis will be in play. I guess the concern would be rotor contact with the ground if these were all in play.
Paul mentioned the Subaru Brat as a tow vehicle and while he may have said it in jest, a small vehicle, at least low in height, would be my first choice. Vans or pickups do block some air to the rotors which leads to a longer takeoff run. The Chapter 62 trainer does have an electric prerotator but one of the things a boomtrainer teaches is rotor management so it wouldn't be used at first. The pilot will know when he is in 'clean' air once he gets off the ground. I happen to have an ole Honda Del Sol that I'd like to try as a boomtrainer tow vehicle.
I mentioned a trained towing team and that is one of the things Craig will mention if you talk to him. He feels it is extremely important. Also communication between pilot and tow team is required. Though hand signals have been used there can be misunderstandings as some experienced glider pilots can tell you! The Chapter 62 boomtrainer has a wired intercom. It was intended to install a air speed indicator for the tow driver but that has never been implemented.