Date: Wed, 18 Aug 1999 10:47:07 -0500 From: David Domeier Subject: COZY: Electric gizmos.... George and Carl, re "My manual pitch trim works perfectly, so I am interested in why anyone would want an electric one." My LEZ seemed to be just fine with manual trim, but for some reason the MKIV is a bit more sensitive to manual trim. It always needs a little more tweaking. (I suspect the spring tension was not perfect or balanced) This electric system provides for effortless, very fine tuning of elevator trim. The primary reason I did it, however, is that I have ordered a NavAid autopilot and a S-Tech stand alone altitude hold system. The S-Tech has a feature that turns on a light when the airplane is out of trim, and in which direction. The electric trim unit will provide for very fine tuning while the altitude hold is on. I guess one could do it manually, but it is my opinion this will be more precise and easier, plus I am going to use the original pitch trim bell crank for the altitude hold servo with the motor mounted to the manual trim wood bracket. It should be a relatively easy installation with the sensor and control unit mounted just aft of the lower instrument panel under my seat. To answer your question, Carl, about back up trim if the unit runs away, the answer is no. It will require flying the airplane with elevator stick force to over come the cylinder spring tension. I do have full elevator travel if the unit runs away in either direction. It is my opinion that the likelihood of a failure of the momentary on-off-on switch is remote. It is quite rugged and there are no relays. Also, I have it wired through a switch on the Lanza electric panel, so if I can figure out what is going on in time, that switch will kill power to the unit. As a side issue, the Steve Wright retraction system (another neat electric gizmo) is controlled by relays and roller switches which if failed will cause some structural damage since there are no internal motor limit switches. I am thinking about installing that same momentary on-off-on switch to control it along with a light indication of full up/down. It would be a pain to have to hold that switch for gear up and down, but it would provide a relatively simple fail/safe system if one of the roller switches or a relay failed. I fly many short local flights and probably have over 150 retraction cycles, with no problems, but I wonder if and when a relay or switch will fail. If Steve could figure out a way of installing internal limit switches on that motor, and it is a powerful beast, I would be more pleased, yet, with the unit. dd From: "Wilhelmson, Jack" Subject: RE: COZY: Electric gizmos.... Date: Wed, 18 Aug 1999 14:55:47 -0400 David: The motor gearbox does have a mechanical slip clutch in it to protect the nylon gears. This slipclutch is a last resort type of system and should not be used as a stop. Also, this clutch produces a lot of torque before it slips and may cause other damage. A simple solution that has worked for me is: Use a 10 amp circuit breaker. The motor is a DC motor and one of the charateristics of this type motor is that they draw current very proportional to their load. Test the breaker with a steady current to make sure it is close to the 10 amp holding limit. Max current during nose lifting is about 8 -- 9 amps on my system. You might want to check this on yours to make sure the 10 amp overload is ok. I have this type of protection on my airplane that use a nose lift system of my own design but uses the same motor and gear box and has worked several times when the micro switches where set to close. Jack Wilhelmson N711CZ > -----Original Message----- > From: David Domeier [SMTP:david010@earthlink.net] > Sent: Wednesday, August 18, 1999 4:47 PM > To: George A. Graham; Canard mail list; cdenk@ix.netcom.com > Cc: cozy_builders@canard.com > Subject: COZY: Electric gizmos.... > > George and Carl, > > re "My manual pitch trim works perfectly, so I am interested in why > anyone > would want an electric one." > > My LEZ seemed to be just fine with manual trim, but for some reason > the MKIV is a bit more sensitive to manual trim. It always needs a > little more tweaking. (I suspect the spring tension was not perfect or > balanced) > > This electric system provides for effortless, very fine tuning of > elevator trim. > > The primary reason I did it, however, is that I have ordered a > NavAid autopilot and a S-Tech stand alone altitude hold system. The > S-Tech has a feature that turns on a light when the airplane is out of > trim, and in which direction. The electric trim unit will provide for > very fine tuning while the altitude hold is on. I guess one could do it > manually, but it is my opinion this will be more precise and easier, > plus I am going to use the original pitch trim bell crank for the > altitude hold servo with the motor mounted to the manual trim wood > bracket. It should be a relatively easy installation with the sensor > and control unit mounted just aft of the lower instrument panel under my > seat. > > To answer your question, Carl, about back up trim if the unit runs > away, the answer is no. It will require flying the airplane with > elevator stick force to over come the cylinder spring tension. I do > have full elevator travel if the unit runs away in either direction. It > is my opinion that the likelihood of a failure of the momentary > on-off-on switch is remote. It is quite rugged and there are no > relays. Also, I have it wired through a switch on the Lanza electric > panel, so if I can figure out what is going on in time, that switch will > kill power to the unit. > > As a side issue, the Steve Wright retraction system (another neat > electric gizmo) is controlled by relays and roller switches which if > failed will cause some structural damage since there are no internal > motor limit switches. I am thinking about installing that same > momentary on-off-on switch to control it along with a light indication > of full up/down. It would be a pain to have to hold that switch for > gear up and down, but it would provide a relatively simple fail/safe > system if one of the roller switches or a relay failed. > > I fly many short local flights and probably have over 150 retraction > cycles, with no problems, but I wonder if and when a relay or switch > will fail. If Steve could figure out a way of installing internal limit > switches on that motor, and it is a powerful beast, I would be more > pleased, yet, with the unit. > > dd From: SWrightFLY@aol.com Date: Wed, 18 Aug 1999 14:40:09 EDT Subject: Re: COZY: Electric gizmos.... In a message dated 8/18/99 10:52:48 AM Central Daylight Time, david010@earthlink.net writes: << I fly many short local flights and probably have over 150 retraction cycles, with no problems, but I wonder if and when a relay or switch will fail. If Steve could figure out a way of installing internal limit switches on that motor, and it is a powerful beast, I would be more pleased, yet, with the unit. >> Great question and one we were concerned about as the system was being developed. Bottom line........we have never had a relay or switch failure and the rated cycles for them will (we think) about equal the life of the airframe. The system does have an internal clutch which will slip and prevent serious damage should the system "run away". We considered "internal switches" but we chose to keep them external so we could keep the design simple and have them visible so they can be easily inspected. We were very concerned about dirt, water, etc., getting up in the tube where the ball screw functions so we chose to keep that sealed on the advice of theThompson Saginaw engineers. Steve Wright Aircraft Works LLC: Electric Nose-Lift for EZEs Date: Wed, 18 Aug 1999 07:44:10 -0400 (EDT) From: "George A. Graham" Subject: COZY: Manual pitch trim My manual pitch trim works perfectly, so I am interested in why anyone would want an electric one. I read the pilot reports on the canard/trim website, and it appears that the greater "authority" of the unit is the big bonus. I followed Vance Atkinson's plans for his trim spring "cylinder", then connected it to my pitch trim handle, instead of the electric motor. See CSA Jan 95, page 11 My trim handle is in the center console, aft of the center mounted stick. George Graham RX-7 Powered Graham-EZ, N4449E Homepage From: "Nat Puffer" Subject: COZY: pitch trim failure Date: Wed, 18 Aug 1999 09:33:56 -0500 Builders, There has been some fear expressed (needlessly) about what would happen if Alex' pitch trim unit stuck or "ran away". I flight tested Alex first prototype. It had a coarse thread on the lead screw, and a motor that wasn't as powerful as currently, and also had a resistor wired in series. On a long cross-country from Mesa to Arlington to St. Paul to Oshkosh, to Mesa, with many stops in between, the trim stuck with the elevator set for take-off. There was no problem overpowering it in cruise. Upon our return to Mesa, I discussed this with Alex, and he modified his unit to a finer pitch on the lead screw and a more powerful motor. It has worked just fine since. Don't worry about imaginary problems! Regards, Nat From: cdenk@ix.netcom.com Date: Wed, 18 Aug 1999 16:30:52 -0500 (CDT) Subject: COZY: Re: Electric gizmos.... Was said I'll give 2 examples from last weeks flights to Wyoming: 1: The plan was From Lincoln, Nebraska to stop a Rawlins, Wy. as a potty stop. A thunderstorm was setting over the airport (one of 3 we could see with 100 mile visibility) The nearest suitable airports probably were Rock Springs and Cheyenne, at least a half hour away. 2: On let down from 11,000' approaching home, passed through a cloud deck from 7000' to 4000' at 400 feet per minute for ear comfort took about a half hour. Try flying the plane for a half hour either enroute or preparing for an approach, while passing through a cloud deck. I am sure such a unit would not pass FAA certification funtionally, and I wouldn't have one on my airframe. I believe the correct functionality: The trim system has an infinite motion, with a slip clutch. If runaway, open the breaker or fuse (easily accessible in flight), then (and the same if mechanism froze) normal adjustment by slipping clutch, just like the adjustable friction shown on the drawings. Date: Thu, 19 Aug 1999 11:23:37 -0500 From: David Domeier Subject: Re: COZY: Re: Electric gizmos.... Carl, I disagree with your conclusion concerning this simple trim system in an IFR airplane. (re ".... and I wouldn't have one on my airframe.") I have no interest in promoting the system, Carl, but I think we should keep the total risk of single engine IFR flight in perspective. The momentary on-off-on switch controlling pitch trim is of very high quality, not stressed by heat or vibration, and is of low usage. The contacts are spring loaded open - even if the spring fails, moving the switch to off should stop the motor. There are many more critical moving parts in the engine than in this trim system. I am more concerned about engine failure than failure of the this trim system. dd From: cdenk@ix.netcom.com Date: Thu, 19 Aug 1999 16:44:44 -0500 (CDT) Subject: Re: COZY: Re: Electric gizmos.... was said I have had to replace numerous switches of various qualities from very cheap to expensive in the years that I have used various equipment, probably starting with a heathkit FM-1 tuner, but I wasn't thinking of only switch failure, but also such items as fuse or circuit breakers, motor, bearings, linkage type items, or whatever. Murphy's law controls. Re: Single Engine IFR: I respect that very seriously. On last weeks flights from Cleveland, to Pinedale, Wyoming, we stopped twice overnight due to weather, and filed IFR twice. The 1st IFR was Lincoln, Nebraska to Pinedale had a couple of 600 overcast and 5 miles in fog reports. We went at 10,000', was in the clear with more than 20 mile visibility all the way. The 2nd was also with a couple of 900' overcast and 3 miles and light rain. Climbed through 2800' to 4000' overcast layer on departure, on arrival it was into the clouds at 7000', and broke out at 4000' with 15 mile visibility. The lowest ceiling approach I have done with the Cosy was breaking out 1000' above the airport with at least 5 mile visibility. Though practice all the time down to minimums. The 2 weather stops were westbound 30 miles past Lincoln, Nebraska, visibility went from 30 miles to 8 miles in a short period, widely scattered thunderstorms were reported. I could no longer assure myself (visually) that I wasn't going to fly into a thunderstorm, turned around and landed a Lincoln. The 2nd weather stop was, stopped at Lincoln for fuel, line of thunderstorms, rain, etc. would have stopped us after another half hour flying near Pella, Iowa. Not worth it to get into the air for that short time. Line too long to do an end run. See future Central States Newsletter for full story. Date: Fri, 27 Aug 1999 15:38:26 -0700 From: "LCDR James D. Newman" Subject: COZY: Re: Electric gizmos.... Hi Dave and All, Sorry I didn't chime in sooner. Been gone. > David Domeier wrote: > To answer your question, Carl, about back up trim if the unit runs > away, the answer is no. It will require flying the airplane with > elevator stick force to over come the cylinder spring tension. I do > have full elevator travel if the unit runs away in either direction. It > is my opinion that the likelihood of a failure of the momentary > on-off-on switch is remote. It is quite rugged and there are no > relays. Also, I have it wired through a switch on the Lanza electric > panel, so if I can figure out what is going on in time, that switch will > kill power to the unit. I've mentioned this before (twice Oct. '97 & once May '98 - should be under 'Electric Trim' in the archives), but I helped Todd Morgan come up with a trim system using a linear actuator that spliced into his stock Cozy III trim system that could easily be removed by reaching under the panel to pull a pit pin to drop a defective trim actuator, or you've lost all electrical, out of the way, and the trim system immediately reverts back to manual. Besides winning Osh Grand Champion that year ('95), he won the Stan Ditzke Safety Award for this system using our grips. So, if you're really that concerned with actuator and/or electrical failure, the pit pin could probably be incorporated into the really nice Strong Trim System. Infinity's Forever, JD