HighAltitude;n1141763 said:
I just completed my MTO 2017 build on Monday and I took the time to run through some scenarios:
1. You cannot pre rotate in brake mode. There is a micro switch on the control shaft that prevents the prerotator from engaging until you move the stick back. The prerotator only engages when the stick is within range. Too far back or forward and prerotation stops. There is also a pressure switch to prevent prerotation with any pressure in the system. You must have the stick in the correct position AND no pressure in the system so you cannot prerotate in brake mode. You can learn it with engine off and key on. I don't understand the comment that it is not understood and involves guessing.
2. Switching to brake on takeoff roll. The pressure switch is set at about 2 bars. It will allow pre rotation at 2 bars or less but at that low pressure there is no braking pressure and the stick is easily pulled back. This is likely what happened to Phil. The PIC may have put it in brake mode but didn't build pressure. If he was trimming on climb out, it was poor technique.
2. Nothing happens immediately and suddenly when you engage brake mode in flight. The "Brake" position is really "Brake Armed". You have to take a second action to apply the brake. Rather than asking "Can you prerotate in brake mode?" the question should be "If a student engaged brake mode in flight, what would happen?". You do not fall out of the sky, nor does the stick go full forward with maximum force. Absolutely nothing happens. You would never know it was in brake mode if you never needed aft trim during your flight. Until you take the second step and build pressure use the trim switch, you wouldn't know the switch was in brake mode. If and when you trim aft in flight you will start to feel forward stick pressure when trimming aft. Again, with the engine off, it can easily be simulated. I imagine that if I pulsed aft trim in flight and the result was more forward pressure instead of less, I would notice it and probably bump the trim again. It would get slightly heavier and responding the opposite of what I intended so I imagine that I would try forward trim. I hope I would not panic and hold the aft trim button until stick forces required two hands but I can see how that scenario would cause confusion. However, a student could/should be taught not to mess with any trims during take off. Level off and then set trim. I will practice today in the hanger with engine off by switching to brake mode and then applying aft trim to get a feel for it and practice switching back to flight mode to feel the instant release of forward stick forces.
I have a brand new MTO sitting here that I know very well having just built it so if anyone wants me to test other scenarios that I may have not covered above, I would be happy to run through them in an effort to keep us all safer. I encourage everyone with an autogyro to sit in the seat, flip on power without starting the engine, and run through the scenarios that I did. I have a much better understanding of what to expect. We are all here to learn and help each other.
I'm sorry but this post is both confused, misleading and ultimately contradictory.
You absolutely CAN pre-rotate in brake mode and you say so yourself having told everyone in point 1 that you can't! That is misleading, in the context of what we are trying to explain dangerous and proves the point I was trying to make initially. People are confused on the issue.
SO TO BE CLEAR YOU CAN PRE-ROTATE IN BRAKE MODE.
The point I was making had nothing to do with the stick position - and therefore the micro switch has no effect on the issue I was describing.
Your own point 2 contradicts your point 1.
Regards point 3. Is nothing about selecting the BRAKE mode in flight and everything to do with the fact you think you are in FLIGHT mode because the switch has been selected incorrectly from take off.
The confusion comes like this....
You have just built a brand new MTO 2017 and at some point you perhaps do some flying with an instructor or maybe you read these forums. The question is made about the BRAKE / FLIGHT switch and the answer is given "no you can not pre-rotate in brake mode". So now for ever and a day you are flying around in the belief that you can not do what you absolutely can do! So when it happens why do you look? You didn't even think it could happen never mind what the function of it happening actually are!!
YOU CAN PRE-ROTATE in BRAKE mode. 100% I've been sat in an aircraft that has done just that. Am I dumb I didn't figure it out in the air? Perhaps. Was that where my thinking was? No because when I did a check ride for the aircraft it was never mentioned. The POH didn't mention and in my case [perhaps in this accident too??] I was a passenger until it got too much for the pilot flying. So you get handed a poor situation. Yes you can fix as you describe by simply dumping trim pressure BUT that is not what your brain is telling you is wrong. You expectation is that it is something else causing an issue and you want to get on the ground. That working out well depends on where and how you fly i.e. airmanship not flying over congested areas etc.
Once again to be clear. Pilots are generally casual with the BRAKE/FLIGHT switch. In so far that they are happy to switch from one mode to the next without it being part of a planned "checklist" style action or point. Indeed you can find YouTube footage of the accident pilot and his use of this switch and it is clear that it is not part of a lining up or departure fixed process.
The issue I had was [in my opinion] was caused because the pilot had flicked modes prior to lining up, got delayed and went into "auto-pilot" and flicked the switch again without actually reading or focused on what he was doing. With system pressure low - because it is very common with many Auto-Gyro Calidus and Calavon pilots to relieve stick forces to trim fully forward [i.e. dump any rearward trim pressure] once they go to FLIGHT mode. The problem is if distracted and they end up back in BRAKE mode you can pre-rotate.
Is it a problem? Well with good awareness arguably no more than having retractable undercarriage. BUT like all systems it is good to understand them and people in general believe you can not do something I know [and the system knows] is possible. Worse in a Cavalon both the switch and the pressure gauge are located in a position where the leg covers both so neither are visible with a casual scan.
Do I think it is relevant to the accident? Whilst I do not know what has caused the accident and will wait for the report I do feel it has the potential to have been a factor and I highlight to you guys here because of the confusion over what happens etc in the scenario.
Ultimately aircraft do not end in a fatal accident with experienced crew without reason and if you look at the time from take off to accident then something went wrong that wasn't engine related if you read the interim NTSB report so this is one possible control issue, which due to the unknown nature and my experience when it happened the only thing that stopped us from a similar situation was we were not flying over wires or a congested area. At 100ft AGL we still had not figured out our issues and had power lines been in our path we would have possibly hit them too.
Regards Rotor RPM as you all may know the rotor is in auto rotation and so RRPM is a function of loading. I closed the throttle in order to descend and maintain best glide speed and keep the disc loaded. Vance has explained the point well. I have a YouTube set of videos on gyroplane technique under my flying school name The Gyrocopter Flying Club for general flying stuff.
Any issue I would have had in the landing phase - had it come to that - would have been the fact it would have been a downwind landing and in a field. Turns were not going to be accurate and we had few options with the initial height. It is likely had we had to land the aircraft may have been damaged but I was confident we would likely have walked away. However in the grand scheme I was happy to take that given the situation moments before.
Please don't get confused with the issue. The BRAKE/FLIGHT mode is not something that causes RRPM to decay because of the mode being BRAKE (other than if you genuinely do bunt and then its low g and not the rotor brake that is causal). Stick force is the issue and the fact the aircraft is in a state that has maximum forward stick and you are not only working as if there was no trimmer but also against the pneumatic system pressure forcing it the other way. All this while stressed and trying to figure what is happening. Its ok for a minute but as you get tired the stress increases for obvious reasons.
Ultimately regardless of its application to this accident it is worth knowing - fore warned etc.