Cobham/Chelton HeliSAS
Wondering if anyone has insight/opinions re this product? Recently issued STC for R44 and TSO'd, with STC for 206 and 407 said to be in the works for first half 2010. Here are some links which provide a fairly comprehensive description and demo:
http://www.helisas.com/UserFiles/Fil...alOverview.pdf Thanks, EN48 |
I never heard low cost and military in the same paragraph before . I wonder What the installed cost is , what percentage of deliverd R44 have hyd coost ?.
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I wonder What the installed cost is , |
That does sound like a good price ( sorry for my spelling ) my recollection of the SFIM was that the computer alone cost close to that price. The demo tape is impressive though.But as my phone now has more computing power than my first computer this sounds reasonable.
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I flew an early prototype at least 5 years ago with Roger Hoh, the developer. The article appeared in Helicopter World, I believe. Anyone who wants to pm me can have the draft of the report.
I was impressed - it was designed to work best in forward flight, but actually made hovering slightly easier as well. Well thought out - but then again you'd expect that from Roger, who wrote most of the new military handling qualities specification for helicopters. Without droning on, during a long transit from one airport to another (including liftoff and touchdown and transition to and from cruise), I needed to press the trim release a total of 5 times. The device moves the stick, and in the light turbulence encountered, it moved the stick about half a second before I would have made the same correction. Nice to see they have it approved! Just wish it hadn't taken so long. |
I think it's a great idea that someone has put a low-cost autopilot system for helicopters on the market. I think it is a great pilot aid for VFR flight.:ok: But ironically, the one thing this system is NOT is a "SAS." The name choice is most unfortunate because it is misleading.:=
The reason the Chelton/Hoh system is low cost is because it uses "parallel" actuation only. That means it works in parallel on the controls, applying force through a spring. It's like having someone in the other seat on the controls applying force to correct your flying. But other than the sensation of spring force back to the pilot, there is no real assistance to stability when the pilot is on the controls. A true Stability Augmentation System (SAS) or in some cases a Stability and Control Augmentation System (SCAS) works in "series" with the controls and adds or subtracts from the pilot's control inputs in order to augment the stability or boost the control input as the flight situation demands. For example, in turbulence a governed power system will increase and decrease power which in some helicopters leads to tail wag. A true SAS or SCAS system will detect the power changes, see the wag, and put in the corrective yaw control before the pilot even notices. And all this happens without the pedal positions ever moving. A true SAS or SCAS does this same thing on pitch, roll and yaw and actually improves the flying behavior of the helicopter. It can fix handling quality problems like the power/attitude to airspeed/altitude relationship. This is especially important when you are trying to meet the stability requirements specified in Appendix B of the FAR 27 and 29 for IFR. So a helicopter autopilot with "true" SAS will have fast-moving series actuators to improve handling and stability, and slower-moving parallel actuators to control the helicopter when the pilot is off the controls. The SFIM autopilot mentioned (which became SAGEM and now SAFRAN) has a basic 2-axis autopilot (pitch and roll parallel trim actuators) with a 3-axis SAS (pitch, roll, and yaw series actuators) So this system provides a true SAS. To that you can add a yaw damper computer with another parallel actuator on the pedals. To that you add a flight director computer for coupled ILS and the like. (In true SAGEM fashion, the intent seems to be to sell as many boxes as possible.) This causes it to be a somewhat overpriced system with a more-complex-than-necessary installation.:ugh: But it is a more capable system. IFR Helicopter autopilots like those in the S-76 and 412EP usually require 2 sets of series actuators on each axis driven by independent computers. (That means the system has 6 series and 3 parallel actuators) . Each of the flight control computer uses a separate set of flight sensors. This is because the series actuators operate rapidly enough so that if something went wrong, they could turn the helicopter "dirty-side up" before the pilot could notice it and grab back the controls.:eek: So you need a second system, just as powerful as the first that will immediately add or subtract control input in the opposite direction to keep the helicopter "dirty-side down." This is called "fail passive" operation. 4-axis autopilots add a 4th trim actuator on the collective. 4-axis autopilot allow you to couple both a speed and a vertical mode (like glideslope) at the same time. This is really nice for the new WAAS steep helicopter approaches where you want to have the glidelope on collective and speed on pitch.:cool: But back to the "HeliSAS" system: It is a 2-axis (pitch and roll) parallel-actuator only autopilot system. (2 faster moving actuators than traditional trims as I understand it). It can fly the cyclic when you need it, and nudge in corrections to your hand flying when you are on the controls. In a lot of cases, that's good enough and it's a handy aid to have. Unfortunately all these systems are called "Autopilots" and the word SAS in the name doesn't mean you are getting one. Be sure you know what you need and what you're getting. |
Be sure you know what you need and what you're getting. |
Avnx EO:
There is no officially designated definition for what constitutes a SAS. I've used an academic definition in my book (and flight test lectures) to help students understand what the various terms may mean. But every manufacturer is free to call their system whatever they want. This system combines the series and parallel actuators into one system (wish I knew exactly how they did this - must be pretty clever). It's an object lesson to all of us to make sure you know what the terms mean and how the system operates. |
Actually AFAIK, the "Bell Subsidiary" picked up the SAGEM/SFIM STC as part of the package deal when HAS went bankrupt (i.e. they didn't specifically go out and choose that system.) My understand is that the Chelton/Hoh system is not yet certified on the 407. And If I were them I'd do the 206 first before biting off the 407. The 407 is likely to be a bit of a challenge because of the control responsiveness compared to a 206 or R44.
If it works on the 407, I think the Chelton/Hoh might be a smart buy. As long as you keep in mind its limitations. But until it's certified for the 407, I'm a skeptic when it comes to what people promise in autopilots. Marrying autopilot to airframe is an artform. Just because it works on one model doesn't mean it will perform anywhere near the same on another. I've seen people stuck with a non-working, uncertifiable system and a half disassembled aircraft. (The HAS-promised 427 autopilot based on the 407 SFIM/SAGEM is a classic example of that.) |
Shawn... it can't be a "series" actuator unless its in "series". I've seen the installation and it is a parallel actuator (they don't cut the control tubes to put in the actuator.)
I've also heard that same statement: that they "combine" the series and parallel actuators into one. That's a bit of an overstatement. You can't apply a series input with a parallel actuator.... by definition. What I understand they are doing is using a fast-moving parallel actuator that is limited from large authority over-travel by clever monitoring. This allows the system to be responsive enough for the fast and fine control movements in small scale (like those traditionally done by a series SAS actuator) but then still use the same actuator for the long-travel slower positioning one needs for trim centering. This is a truely cost-effective and clever way to do a hands-off system. But other than the nudges it gives you in parallel to your own actions, there is no handling quality improvement to the extent you get with a true SAS with the pilot hands-on. |
One more thing....
There is no officially designated definition for what constitutes a SAS If a SAS installation stabilizes the rotorcraft by allowing the pilot to "fly through" and perceive a stable, well behaved vehicle, it qualifies as a SAS... I'm not saying its a bad system. But if it's primarily a hands-off system, it's a clever autopilot - not a SAS. |
And If I were them I'd do the 206 first before biting off the 407. The 407 is likely to be a bit of a challenge because of the control responsiveness compared to a 206 or R44. According to press coverage, this is the plan. Cobham/Chelton has announced that they will do the 206 first, followed by the 407. The link in my first post to the Technical Description of this system actually shows photos of the servos installed in a 206. Here is an excerpt from a recent press release: "Previously, Cobham has received a Supplemental Type Certification (STC) from the FAA for HeliSAS use in a Robinson R44 helicopter, which the Company announced on 23 November 2009. Cobham is in the process of achieving HeliSAS certification for use on the Bell 206, Bell 407, Eurocopter AS350, and the U.S. Navy's Bell-made TH-57 helicopters" Your point about being wary until it is certified on the 407 is well taken, as aviation is full of missed expectations. Another Cobham/CHelton press release: News October 19, 2009 (MINERAL WELLS, Texas) Cobham Avionics announces that HeliSAS certification activities have begun on the Bell 206B and 407 helicopter models. Cobham is partnering with Edwards & Associates, Piney Flats, TN, for HeliSAS installation and certification on the Bell rotorcraft. The two-axis VFR STC program on both of these models is currently in the flight testing stage at Edwards, and early B206B results have been positive. In addition, HeliSAS components are being fitted on the B407, which is expected to be in flight test by early December. FAA certification on the B206B is anticipated in January, 2010 with the B407 to follow by April. Cobham Avionics has also plans to introduce HeliSAS on the Eurocopter AS 350 models and EC 120 later in 2010. |
You obviously know a thing or two about autopilots... but this IS a SAS. You definetely have to demo this one. You WILL be impressed.
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I contacted Cobham/Chelton after they received the FAA STC for the R44 and was told they weren't currently considering EASA certification, then a week or so ago I contacted them again for another R44 customer and was told that due to insurance issues the equipment was not currently being sold for R44's. I'm not quite sure what the state of play is.
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I'm not quite sure what the state of play is. |
Is Chelton a common FMS ? In one of my classes at Embry-Riddle we learned to use Chelton, I thought it was great but don't know when I will ever use it. :ok:
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Is Chelton a common FMS ? |
I fly the Chelton EFIS system in a fixwing. It's a very good piece of kit however there is a lot of button pushing. Updates are done through Jeppesen and are very easy, the terrain and obstruction database I find useful when landing at smaller airports often in mountainous terrain decending IFR. So I imagine it would be very good also in a helicopter when flying in marginal conditions.
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I had an opportunity to fly a B407 with the Chelton HeliSAS this week. Quite impressive and a definite safety enhancer. We tried a number of extreme attitude manuevers and found that the system returned the helicopter to straight and level with no drama by simply releasing the cyclic. Handles a coupled approach nicely, which may be useful for IIMC encounters. I have no other experience with helicopter autopilots, but do have substantial airplane AP experience and the HeliSAS seems quite comparable to AP's used in light SMEL airplanes. :ok:
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That's very cool. I have been talking to them for the last 6 months about getting the whole system put in my Eurocopter EC130, but i can't get them to give a price or tell me how long it would take. It looks like a great system and I love the Chelton in my Enstrom. I was hoping to put it in the EC 130 and add the autopilot. I think now, i am going to do the new Garmin G500H and give up on the Heli-SaS...now I have to wait on the darn stc for the Garmin.
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I have been talking to them for the last 6 months about getting the whole system put in my Eurocopter EC130, but i can't get them to give a price or tell me how long it would take. It looks like a great system and I love the Chelton in my Enstrom. I was hoping to put it in the EC 130 and add the autopilot. I think now, i am going to do the new Garmin G500H and give up on the Heli-SaS...now I have to wait on the darn stc for the Garmin. |
I've come to really like the Chelton in my 480. (I didn't get it at first) I really wanted to put it in the 130, but like you, when I saw the G500H, I decided it would be a VERY reasonable compromise. I can't wait to get it installed.
I will miss the simulated ILS approaches and how easy the Chelton is to use etc. The Chelton has been amazing as I have worked on my Commercial and Instrument ticket. Putting an IFR certified Chelton/Cobham system in a single engine, VFR ship is probably not the best investment for me. Chuck |
EC130B4 HeliSAS
I was getting excited reading the very knowledgeable discussion regarding SAS, and the HeliSAS system, until I read the last post re installation in my EC130B4.
I spoke to Sagem over a six month period trying to get prices, info on the STCs etc, They were incredibly slow, sometimes two months between replies. An installer in UK has a R44 in pieces, with a half installed Sagem SAS/autopilot/EFIS still waiting on Sagem. Grounded for 6 months! I am not willing to risk grounding my machine, particulalry as installation requires removing the control rods and sending them to USA to be sawn in half and actuators fitted. The HeliSAS sounds superior in its simplicity and weight, although it may not be as capable. Given that a single engined helicopter cant be flown IFR in UK anyhoo... I would be happy with the additional safety of the HeliSAS. Does anyone know if Cobham are seeking an EASA STC? All the press talks about FAA, and they havent replied to my emails... |
As for R44 STC and why it is not being sold so far, see the post in the HeliSAS/R44/Light Helicopter thread:
http://www.pprune.org/rotorheads/440...ml#post6216082 This was posted by Roger Hoh to the RHC Owners Group in March 2010: The HeliSAS autopilot and stability augmentation system received STC for installation on the Robinson R44 on Oct 30, 2009 (STC SR02254LA). It is installed on one R44 helicopter, which has a standard airworthiness certificate and it works great. HeliSAS consists of an attitude-command-attitude-hold SAS that can be engaged from engine start to shutdown. With the SAS engaged, the helicopter maintains level flight with hands off the controls, and has been demonstrated to automatically recover from extreme unusual attitudes. Hands-off hover, takeoffs, and landings have also been demonstrated. HeliSAS will be offered as a SAS-only or full autopilot option. The full autopilot option includes heading hold, altitude hold, GPS and VOR navigation modes, ILS, backcourse, and LNAV/VNAV approach capability. Unfortunately, HeliSAS is not being sold for installation on the R44 at this time because of liability insurance issues. The problem is that the Robinson Helicopter Company does not carry liability insurance. Therefore other insurer's are unwilling to be "first in line" . Work is in progress to resolve this issue. Work to achieve approval for HeliSAS as a factory option was halted in April 2009 so that Robinson engineering could focus 100% on R66 certification. It has come to our attention that there is a rumor circulating to the effect work was stopped at the factory because the technology is "not sufficiently mature". This is not the case. HeliSAS has been certified to the latest FAA rules including extensive DO 160F environmental testing (including the new HIRF rule) and the software was certified to the highest available standard (DO 178B Level A). This is the same standard that is used for certification of software for fly-by wire transports (e.g. Airbus). The market for HeliSAS for R44 helicopters is not known. Any input from members would be very useful to understand the viability of this product for the R44/R66 market. |
HeliSas
Well you could sell one to this EC130 owner if you got an EASA STC. So far my enquires to Cobham have not received a reply.
Its a great product. Hopefully Cobham will get of the ground and get some STCs in place. |
The HeliSAS installation in my B407 was completed by Bell/Edwards yesterday and I participated in the test flying today. First impressions are very positive. There has been additional development work since I flew a prototype more than a year ago which results in better handling qualities. Only negative so far has been an extended delay in obtaining FAA certification, but that is now complete. :ok:
At present, the SAS provides a force trim function and the AP loop provides typical functions such as heading hold, alt hold, and nav coupling in both lateral and vertical modes. I have been told that further development is underway that will provide a trim capability via a coolie hat switch on the cyclic. |
very cool..thanks for the report.
I heard over the weekend that an STC became available to install it in my EC 130. I have my avionics shop checking into it. Chuck |
Confirmed, now certified for the EC130 and AS350 B2/B3 via a partnership between Cobham and Metro Aviation.
I/C |
EN48, all you need now is the G1K upgrade :E:E
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I flew this auto pilot in a Bell 407 with G1000, back in April, and it reminded me of the Honeywell auto pilot in the G1000 fixed wing aircraft prior to the Garmin auto pilot/flight director. It controls the aircraft reasonably well, but is barely integrated.
If Garmin develops a FD/AP for the 407 G1000 installation, similar to their fixed wing auto pilot/flight director available in the Mustang/Caravan and other single engine aircraft, the HeliSAS will become a distant memory, just as the Chelton EFIS system has mostly become with the availability of G500H and G1000 in rotorcraft. |
but is barely integrated. |
EN48, all you need now is the G1K upgrade |
EN48
And, I am still dealing with bugs in the G500H software, some of which are still not resolved and will require additional fixes. In talking to Garmin yesterday, they told me that some of these could take "2-3 years" to resolve." (If ever) In the next paragraph you say, "avionics are a moving target and most exciting new avionics look like antiques in 5-7 years no matter who makes them" I totally agree regarding the moving target but we are paying large amounts of cash for a product, that has known bugs, is it not time that the manufacturers were made to address these as a matter of urgency rather than in their own good time ? you have paid for a product that could be at least half way through its useful life by the time they bother to sort problems out. In our industry they then turn to the other excuse, it is old technology the new equipment will be available soon! (with a new set of bugs):ugh: |
G1000 in the 407 is far more than fixed wing G1000 dropped into a rotorcraft, and there are many rotorcraft specific features that make the installation light years ahead of anything else ever put in a VFR helicopter.
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And, I am still dealing with bugs in the G500H software, some of which are still not resolved and will require additional fixes. In talking to Garmin yesterday, they told me that some of these could take "2-3 years" to resolve Can you elaborate on the problems that you're having? I'm doing some research on the various systems and could use some background, thanks. |
Can you elaborate on the problems that you're having? Garmin Service Alerts link: Garmin: Service Alerts PM me if you want more details. |
many rotorcraft specific features that make the installation light years ahead of anything else ever put in a VFR helicopter. |
we are paying large amounts of cash for a product, that has known bugs 500e, Agree with all your points. Apparently we are willing to part with large amounts of cash to get the improved functionalty even if we have to live with the bugs. Shouldnt happen but it does. And, we arent alone; graphic example: Windows OS. :} |
Why do we as consumers put up with it, It is a reason I dont use MS opperating system other than when I have to.
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I spent some time in the G1000 Caravan sim at FlightSafety today, using only the Garmin synthetic vision depiction of the runway to make dead stick approaches and landings to a 100 foot ceiling, by placing the flight path marker over the approach end of the runway, just as we use a spot on the windshield to make a precision autorotation. This technology is amazing and makes the Collins Pro Line 21 avionics I flew, the three previous days in the sim, seem antique by comparison. Whether on the Garmin G500H or G1000, synthetic vision will offer incredible capability to those flying at night, and/or in low or mountainous conditions.
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