![]() |
If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
|
#1
|
|||
|
|||
![]()
So my AI has been going whacky for several months now -- falling over on its
side, then erecting, and so on. We finally realized that, with night-flying season nearly upon us, we'd better replace that boat anchor with an instrument we can trust. Although we don't fly IFR, we DO occasionally fly at night, and in rural Iowa, that can be essentially IFR. So, I asked my A&P to order the correct one for me, cuz I couldn't see a model number or any identifying marks on the face. Well, it turns out my autopilot is connected to the back of this instrument with a multi-prong plug, necessitating (of course!) the more expensive AI. This also explains (I hope) why my autopilot has been acting erratic, so I'm looking forward to fixing two problems with one purchase. (Ha! Wake up, Jay!) We ended up ordering a rebuilt unit from the Gyro House, in northern California. You pay $1100, and they credit you $600 when they receive your old one back in the mail. Even though I told them there was no rush, the instrument arrived within two days -- before my shop was even ready to install it. It was shipped in a gigantic box, with two huge pieces of foam holding the instrument in the middle of a marshmallow-like suspension. So far, I'm very impressed with their helpful attitude on the phone, and their quick service. I hope it will be installed Monday or Tuesday. Question: Does anyone know why the old autopilots were hooked up to a vacuum instrument? This seems like the height of folly, since a vacuum pump failure takes down EVERYTHING, as opposed to the newer units that work off the electric turn & bank. -- Jay Honeck Iowa City, IA Pathfinder N56993 www.AlexisParkInn.com "Your Aviation Destination" |
#2
|
|||
|
|||
![]()
"Jay Honeck" wrote:
Question: Does anyone know why the old autopilots were hooked up to a vacuum instrument? This seems like the height of folly, since a vacuum pump failure takes down EVERYTHING, as opposed to the newer units that work off the electric turn & bank. Autopilots come in two species: rate-based and attitude-based. Yours is attitude-based, as are many modern autopilots, especially the high end ones. Rate-based autopilots like my S-Tec 50 tend to be simpler and cheaper. The fact that they continue to work after a vacuum failure is a happy coincidence of the fact that turn coordinators are electric. -- Dan C172RG at BFM |
#3
|
|||
|
|||
![]()
Sure Jay, he attitude gyro tells the autopilot which way is "up." It is used
for pitch AND roll control in a position-based system, like Century (nee Mitchell or Edo-Aire) and King. For instance, in roll, the autopilot will use the gyro angle to cancel the heading error. For instance, if you are 10 degrees off the selected heading, the autopilot will roll in 10 degrees of bank until the heading select error starts to decrease. On heading, the bank angle becomes zero. As you said, the vacuum is one of the least reliable systems, but electric gyros are very expensive, while vacuum powered ones are simpler, and more robust. And attitude information was required in these systems. S-tec avoided the attitude gyro necessity, by using RATE based systems and pressure transducers. --Gary "Jay Honeck" wrote in message news:4DG6b.381210$Ho3.57121@sccrnsc03... So my AI has been going whacky for several months now -- falling over on its side, then erecting, and so on. We finally realized that, with night-flying season nearly upon us, we'd better replace that boat anchor with an instrument we can trust. Although we don't fly IFR, we DO occasionally fly at night, and in rural Iowa, that can be essentially IFR. So, I asked my A&P to order the correct one for me, cuz I couldn't see a model number or any identifying marks on the face. Well, it turns out my autopilot is connected to the back of this instrument with a multi-prong plug, necessitating (of course!) the more expensive AI. This also explains (I hope) why my autopilot has been acting erratic, so I'm looking forward to fixing two problems with one purchase. (Ha! Wake up, Jay!) We ended up ordering a rebuilt unit from the Gyro House, in northern California. You pay $1100, and they credit you $600 when they receive your old one back in the mail. Even though I told them there was no rush, the instrument arrived within two days -- before my shop was even ready to install it. It was shipped in a gigantic box, with two huge pieces of foam holding the instrument in the middle of a marshmallow-like suspension. So far, I'm very impressed with their helpful attitude on the phone, and their quick service. I hope it will be installed Monday or Tuesday. Question: Does anyone know why the old autopilots were hooked up to a vacuum instrument? This seems like the height of folly, since a vacuum pump failure takes down EVERYTHING, as opposed to the newer units that work off the electric turn & bank. -- Jay Honeck Iowa City, IA Pathfinder N56993 www.AlexisParkInn.com "Your Aviation Destination" |
Thread Tools | |
Display Modes | |
|
|
![]() |
||||
Thread | Thread Starter | Forum | Replies | Last Post |
ISRAELI TORTURE CONNECTION: WHO IS JOHN ISRAEL? | MORRIS434 | Military Aviation | 0 | May 12th 04 09:16 PM |
When You Hear The Heavy Accent & The Poor Phone Connection... HANG UP!! ----- hithUOFT8mSo | Aardvark G. Bandersnatch, CPE, RCA, IBM, LSMFT | Naval Aviation | 4 | April 3rd 04 03:17 AM |
When You Hear The Heavy Accent & The Poor Phone Connection... HANG UP!! ----- hithUOFT8mSo | Aardvark G. Bandersnatch, CPE, RCA, IBM, LSMFT | General Aviation | 4 | April 3rd 04 03:17 AM |
Headset with mobilephone connection | Mads | Home Built | 2 | January 8th 04 06:51 AM |
PC connection for GPS 90 wanted | Jim Weir | Owning | 4 | September 2nd 03 10:01 PM |