Do I Need The GFC700?

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Lance Murray
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Re: Do I Need The GFC700?

Postby Lance Murray » Wed Apr 25, 2012 3:43 am

I understand your point but the KAP 140 is rate based and NOT attitude based. There is no gyro in the KAP 140. It does use your turn coordinator to obtain turn rate and it uses the internal barometric sensor to obtain vertical rate.

Tkramer wrote:the KAP-140 has its own, independent attitude gyro.
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Gary
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Re: Do I Need The GFC700?

Postby Gary » Wed Apr 25, 2012 11:13 am

Lance Murray wrote:I understand your point but the KAP 140 is rate based and NOT attitude based. There is no gyro in the KAP 140. It does use your turn coordinator to obtain turn rate and it uses the internal barometric sensor to obtain vertical rate.

And it uses the external static ports to determine porpoising rate and altitude deviation. This is my biggest gripe with the KAP140, can't really use it in moderate or heavier rain without porpoising.
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Re: Do I Need The GFC700?

Postby carym » Wed Apr 25, 2012 3:22 pm

Gary wrote:
Lance Murray wrote:I understand your point but the KAP 140 is rate based and NOT attitude based. There is no gyro in the KAP 140. It does use your turn coordinator to obtain turn rate and it uses the internal barometric sensor to obtain vertical rate.

And it uses the external static ports to determine porpoising rate and altitude deviation. This is my biggest gripe with the KAP140, can't really use it in moderate or heavier rain without porpoising.


Gary,
I don't know if that is a problem with the KAP140 or your installation. I know this issue has been discussed extensively on both boards, but I am unaware of this problem occuring with any of the DA42's with KAP140 installation. Certainly I have not experienced this problem with my KAP140 and I have been in rain, snow, ice, and sleet (maybe I should become a postal worker).
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Re: Do I Need The GFC700?

Postby Gary » Wed Apr 25, 2012 3:27 pm

carym wrote:
Gary,
I don't know if that is a problem with the KAP140 or your installation. I know this issue has been discussed extensively on both boards, but I am unaware of this problem occuring with any of the DA42's with KAP140 installation. Certainly I have not experienced this problem with my KAP140 and I have been in rain, snow, ice, and sleet (maybe I should become a postal worker).

It is a problem with the external static ports for the DA40s with the KAP140 and it appears that the twin engine airplanes are not affected.
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Re: Do I Need The GFC700?

Postby Jean » Wed Apr 25, 2012 6:45 pm

Gary,
We complied with OSB40-050 (Installation of external static pressure source for KAP140 autopilot system - see wiki) and we had the Honywell servos SB complied with when we bought the aircraft. We never experienced any porpoising.
Short finals of ILS approaches must generally be hand flown before reaching the minimums but as you say, SVT makes that very easy.
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Re: Do I Need The GFC700?

Postby carym » Wed Apr 25, 2012 7:08 pm

Jean wrote:Gary,
We complied with OSB40-050 (Installation of external static pressure source for KAP140 autopilot system - see wiki) and we had the Honywell servos SB complied with when we bought the aircraft. We never experienced any porpoising.
Short finals of ILS approaches must generally be hand flown before reaching the minimums but as you say, SVT makes that very easy.


I know that this is getting to be thread creep, but it is still related to autopilot. I fly my ILS approaches at 106 kts because any slower the KAP140 is pretty sloppy. Keeping the speed at 106 kts (or greater) the KAP140 does well all the way down to minimums. Consequently, in order to be consistent I use 106 kts when either flown bye the KAP140 or when I hand fly the ILS. Flying the ILS at 106 kts is pretty easy in the DA42 and I can easily slow it down to the 82 kts needed to land when going from approach to landing flaps. I don't know, however, if this can be done in a DA40.
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Re: Do I Need The GFC700?

Postby Antoine » Thu Apr 26, 2012 5:32 am

Scotsman58 wrote:Thanks for these replies. Very helpful. Sounds like the consensus is to go for it if I can swing it.


Of course. This is a no brainer. The GFC700 is just some extra money you add into your purchase and get back in full or maybe even more whenever you resell it.

Today, weather allowing, I will be doing test flights for the development of maximum performance climb fuel flow tables. i expect to gain 10% on the climb rate.

The requirement is a fixed airspeed climb. Only the GFC700 can do that.

And, seeing the above posts, I'd like to say a word for Premier. They are not the least expensive dealer, but Mr Jeff Owen is the most knowledgeable, service minded and honest salesman I ever came across in any industry. If you are willing to spend a bit more in return for getting the best buy around, you should talk to him.
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Re: Do I Need The GFC700?

Postby Gary » Thu Apr 26, 2012 7:31 am

Jean wrote:Gary,
We complied with OSB40-050 (Installation of external static pressure source for KAP140 autopilot system - see wiki) and we had the Honywell servos SB complied with when we bought the aircraft. We never experienced any porpoising.
Short finals of ILS approaches must generally be hand flown before reaching the minimums but as you say, SVT makes that very easy.

I have had the external static port OSB (and had the installation checked by another shop), both servos replaced and the A/P checked by a good shop and still have porpoising in moderate rain.
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Re: Do I Need The GFC700?

Postby Rick » Thu Apr 26, 2012 11:59 am

Gary wrote:I have had the external static port OSB (and had the installation checked by another shop), both servos replaced and the A/P checked by a good shop and still have porpoising in moderate rain.
Gary, I'm not sure if this is a clue or not, but flying Tim's KAP140-equipped DA40 back from CA last weekend (which normally does NOT porpose), we began to have mild porposing in the climb above 13,000' which got progressively worse the higher we climbed. It would also do it fairly regularly at cruise, too, up high - and all this was in very DRY air. Just an observation...
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Re: Do I Need The GFC700?

Postby Steve » Thu Apr 26, 2012 12:23 pm

I will post this as an anecdotal data point. My KAP140 equipped airplane never porpoises. I have not done the static port SB. I don't usually fly in rain, though. The only thing I have done is the pitot/static line protection SB, but it didn't have a problem before that either...

Just lucky, I guess...

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