HD Module Settings

[rando]

Has anyone considered a 'hack' to override the minimum HD limit? I can think of several approaches from crude to sophisticated.

1) Initialize the system below the flying field level -- depends on topology of your flying field. This is the easiest / no-modification required solution, if available to you.

2) Apply pressure on the tubing during initialization to simulate initialization at a lower altitude. It could be possible to develope a jig to get consistent results. If you inadvertently apply too much pressure, you can then increase the HD limit (for that flight) to offset it.

3) Modify HD module or CPII module firmware -- might need to reverse engineer boot loaders and/or determine if micro-controller programming pins are physically available. It may also be possible to gain entry through the firmware updater software tool.

4) Intercept and modify the communication between the HD module and CPII. An inexpensive micro-controller can likely do this job. I assume this is a simple serial transmission TTL level RS232, SPI or I2C.

[sutty]

Hooray, a relevant post. Good man. Not sure of any of those methods other than number one. I could walk to the bottom of next doors garden and knock off, at a rough guess, ten feet, but as yet I haven't tried it. I imagine it would be easy to see what value I was starting off at by checking to see if it read ten feet, or so, when I got back to the take off spot. One guy who posts on here is about to try this, as he has described that there is quite a deep pit near his flying spot. He plans to take off from the bottom of the pit, and then fly around over the level ground which surrounds it. I'm certain he is aware of the additional risk.

Or, as I think Howard once suggested, one could always stand on top of a tall ladder whilst flying, this will bring it down a good few feet. He was of course joking, but I'm sure you could stand on top of a building or something, like if you had a flat roofed garage or similar. The benefit of that approach would be that it would at least still have the manufacturers recommended 50 feet to play with as and when it performed its recoveries.

I think pinching the pipe makes for very large readings, as just recently Jack described a method for checking that it was reading altitude by pinching the pipe and he said to look for a very large readings, or a very low reading as I think it would be. I think someone pointed out that you would get -1000 or similar. If this were the case then I imagine it would be very difficult to get a reading of say 20 feet when you let go of the pipe, with or without mechanical assistance.

I suppose it goes without saying that any of these ideas to defeat the intended minimum altitude would be against the manufacturers advice, but I suppose people will be people and at least a few are bound to try.

Having recently re-read the reasons that Tim outlined for us as to why he doesn't want us to be able to lower the height limit at our own discretion, with appropriate warnings etc, it got me to wondering if it might not also have had something to do with litigation. I can imagine a court case where the helicopter had flown into a person or property, where the injured party ends up being faced with the defence, "Direct your complaint to FMA. During the incident, when I flew into you, (or your property) I had no control over the heli, as it was undergoing an emergency recovery at the time. This was not my fault, as FMA allowed me to overide their minimum safe altitude setting and bring it down to 20 feet. As a result it didn't recover until it was at 5 or 6 feet, which is why it ended up flying into you (or your property)."

I have been curious to know what lawyers might make of such autonomous accidents, especially on some of the more sophisticated devices that allow for waypoints etc. What if you planned a route which was completely safe at 100 feet, but then an error in the device made it fly back at 10 or less and there was an accident? I suppose they would treat it like any other accident that was as a result of failure, and call upon the pilot's insurance. Would you be covered though if you had fiddled with the device against the manufacturers recommendations? I expect the insurers could easily get out of making a payment on that basis.

Just an idle thought or two.

Cheers

Sutty

[rando]

I can't comment on the litigation potential but don't doubt anything is possible. I would point out that every other component on the helicopter does nothing to prevent me from mis-configuring/misusing it also. Does that make FMA's defense stronger? Who knows.

As far as option #1, it works ... been there done that. And if your flying field happens to be a sloped hill side, then you can get the lower HD without any additional risk at all.

Option #2: Squeezing the tube simulates increased pressure which equates to a lower altitude. This is what you want if you want a lower HD. You can wrap a tie wrap around the tube while monitoring the altitude until you get it somewhere between 0 and -200ft. Then power cycle the system. After a few moments slowly release the wrap and see what the reference altitude now is (should be a positive number now). Now go in and adjust your HD limit to be X ft above the new reference where X is the actual HD altitude you want. The trick here is that the unit seems to have an algorithm for detecting a pinched hose so it's possible the procedure of placing/removing the tie-wrap will be detected as a pinch. This disables the HD -- I need to experiment with this approach more to see if it can be done consistently.

The other options are a bit more sophisticated. When I get some time, I'll instrument the signals with a scope and see what I can discover.

[N3M0]

Well since this post went into another direction at times, that was not intended. I thought FMA may have been working on a new firmware or some other concept to accommodate their users without having a liability issue. Operantly I was wrong, Tim's stance on this seems to strongly hint, that any plans to lower the deck are on the lowest priority list. While also hinting to having something available in the distant future. I still don't know why a pass code and disclaimer wouldn't limit the liabilities if written specifically for this application. JMO, Try not to flame me.

[jperkosk]

Originally Posted by N3M0

I still don't know why a pass code and disclaimer wouldn't limit the liabilities if written specifically for this application.

Fully agree with you on this one, Nemo.

Originally Posted by N3M0

JMO, Try not to flame me.

Contrary to the appearances caused by sometimes very heated discussions we're doing our damnest to avoid it around here, sometimes even at the cost of failing to get the point across

[sutty]

Originally Posted by N3M0

I still don't know why a pass code and disclaimer wouldn't limit the liabilities if written specifically for this application. JMO, Try not to flame me.

Perhaps it would, but liability was not one of the reasons that Tim had mentioned when justifying his company's position. That was mere speculation on my part that it may well have played some part. Perhaps I am wrong, I very often am. As I said, just idle speculation.

Cheers

Sutty

[N3M0]

Automatic limitations is another thought I had. If set under 15' only level flight will be allowed. If set at 20' then auto recovery with no HD and no 3D could be implemented. And finally if set to 30' the HD would be Implemented and 3D allowed. Just a thought.

[N3M0]

Epic Fail!

[pctomlin]

One thing we all seem to be forgetting is this is release #1 of a new product. I am sure Mark is listening, give him a chance and some quiet time to explore the possibilities. FMA makes great stuff and I can see the logic in starting out conservative with the HD.

[N3M0]

Still have a very hard time understanding why a password or disclaimer. Would not solve this issue. I know no one wants to crash, but we all do. Lets take our chances, we already know the CpII is awesome. It will work 99.5% of the time in less than a second. Ill sign the waiver before you email the pass code to unlock the HD setting. Anything could be implemented and still show how well the CP products work. Without anyone getting into trouble.
Maybe,crazy.. am I totally off here?

[pctomlin]

No, I don't think you are totally off. A little lower would be nicer, but we don't know the current limits of HD like Mark does and is currently comfortable with marketing. I hope the HD height can be set at a lower setting in a future update, time will tell.. Until then I am going to enjoy what I currently have.

[N3M0]

I agree! But the squeeky wheel gets the grease!

Im just surprised Mark has not stepped in and told me to STFU!

[ROGER G]

I did some research on the subject and I think they got it right setting the limit to 50 feet. From what I understand designing a pitot/static system for an airplane is a somewhat time consuming effort to make the system as accurate as possible. It is much harder to design a system for a helicopter. With the HD module we are only dealing with static pressure. Tell me, have you ever seen a full size Heli with a feathering static port dangling underneath the Heli ? The static port is the problem. From what I was able to understand, there is no way to get 100% accurate static port pressure, every time in the case of a Heli, especially a Heli doing all kinds of gyrations. IMHO, if you can come up with a better static port solution than what FMA did with their feathering system, and it can be shown to be 100% accurate, under ALL flight conditions, EVERY time, then they would probly lower the hard deck altitude.

[CZorzella]

Originally Posted by ROGER G

I did some research on the subject and I think they got it right setting the limit to 50 feet. From what I understand designing a pitot/static system for an airplane is a somewhat time consuming effort to make the system as accurate as possible. It is much harder to design a system for a helicopter. With the HD module we are only dealing with static pressure. Tell me, have you ever seen a full size Heli with a feathering static port dangling underneath the Heli ? The static port is the problem. From what I was able to understand, there is no way to get 100% accurate static port pressure, every time in the case of a Heli, especially a Heli doing all kinds of gyrations. IMHO, if you can come up with a better static port solution than what FMA did with their feathering system, and it can be shown to be 100% accurate, under ALL flight conditions, EVERY time, then they would probly lower the hard deck altitude.

Roger, I think you are on the right track and what you said may explain it all. The HD solution may not be perfect but it works; It is what it is.

The only thing I question about the CPII / HD solution is if it wouldn't be possible to put the whole system together using a single module. IMHO, the proposed solution using individual modules - avionics computer, main sensor, vertical sensor, IR sensor, HD module and the static port dangling underneath the Heli is kind of awkward and makes implementation a lot more complicated.

[jperkosk]

Gentlemen, you may be technically correct but still are missing a point here. If my setup recovers from my gentle flying each and every time in under 10' I want it to be my responsibility, not Tim's, to be able to set my HD to 25', period. AFAIK he hasn't seen me flying ever, yet he deemed it proper to prevent me from doing just that. Not really complaining here, he has stated his reasons, I just think his position to be completely out of touch with my specific needs.

[N3M0]

Originally Posted by jperkosk

Gentlemen, you may be technically correct but still are missing a point here. If my setup recovers from my gentle flying each and every time in under 10' I want it to be my responsibility, not Tim's, to be able to set my HD to 25', period. AFAIK he hasn't seen me flying ever, yet he deemed it proper to prevent me from doing just that. Not really complaining here, he has stated his reasons, I just think his position to be completely out of touch with my specific needs.

+1

[sutty]

Originally Posted by jperkosk

AFAIK he hasn't seen me flying ever

Kerh, course he has, one of your videos is on the website showing off how the CPII saved your 600.

Cheers

Sutty

[jperkosk]

Well that was back when I was trying to figure out the nose-in and my dumb-thumbing could be very abrupt at times . I promise my dumb-thumbing has become more predictable and gentle since, scouts honor

[ROGER G]

I understand what your saying Jerry, but I think your missing a point. The HD was a mission specific design. That is to be able to practice 3D and have AUTOMATIC ER activation at a safe altitude. Remember, you can activate ER at any altitude you want, you just have to flip a switch. Not a hard thing to learn. If you can convince Tim that there is a market for a HDv2 with a guaranteed error of +/- 10 feet when set at at a activation of 25 feet, well I'm sure they could design it, but they would have to install it on your Heli and test it, to make that gurantee. And would you or any one else be willing to buy it for say $500 or more for that a accuracy ? However, I do not have the HD installed any more on my Heli, but do have a somewhat Semi-Automatic system nearly complete. What I did was to install a mercury switch on my transmitter to activate the ER when I tilt the Xmiter aprox. 45 deg. from level. Works pretty well, just working on a latching circuit so it stays on after tilting the Xmitter back to level. Was not my idea, Jeti has this switch feature on their new but pricey Xmitter.

[CZorzella]

What an awesome idea!
Perhaps you could show some photos and details of this mercury switch you did.