Do I Need The GFC700?

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Gary
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Re: Do I Need The GFC700?

Post by Gary »

Steve wrote: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...

Steve
I did not do a lot of IFR flying before the having the external static port SB but the altitude was usually off by about 100' until I had it done. Now the A/P altitude is dead on until it rains.
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Re: Do I Need The GFC700?

Post by Antoine »

Today I went flying in an attempt to do the calibration test flights for the lean-during-the-climb exercise.

It was very very windy, unstable and gusty. We had to abort the tests. but you should have seen Mr GFC700 hold the 75 KIAS against some really nasty rock n roll.
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ThomasD
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Re: Do I Need The GFC700?

Post by ThomasD »

I have a DA40 with GFC700.
I think it only really matters if you fly IFR. When the wx is really bad and you are getting thrown 30 degree bank angles left and right the GFC700 handles it beautifully.
I would have said before having the GFC700 that I could fly significant turbulence more smoothly by hand than any autopilot - and that was my experience with wing levellers in PA28s.

However, the key thing for me is in real IFR - if the wx is bad, for me it takes a lot of my capacity to just fly the plane, making it really hard work to do everything else that has to be done.
However, the GFC700 takes this load of flying the plane properly, and then take me to the ILS and down the glide slope, even in really bumpy conditions, leaving me to concentrate on situational awareness, monitoring the autopilot and all the other things you have to do...
Or likewise fly a SID or STAR - flew my DA40 into Amsterdam Schipol - you need to be in the right place and the GFC700 handles it all.
And one of the great modes is FLC (flight level change) where you plug in the altitude to go to then also the KIAS you want the GFC700 to maintain (when going up or down) - no need to worry about an autopilot induced stall, as can happen with a simpler autopilot that just gives a FPM up/down rate and the autopilot just tries to maintain this - even if it puts you in a stall.

I am sure that the KAP140 makes life so much easier than without any autopilot, but I do love the features of the GFC700..
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Lance Murray
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Re: Do I Need The GFC700?

Post by Lance Murray »

I don't have that issue. I also do not have the external static port. Try disconnecting that and see what you get. I am pretty sure that my KAP140 has no plumbing for the static system and it has only one sensing port directly behind the controller.
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.
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Gary
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Re: Do I Need The GFC700?

Post by Gary »

Lance Murray wrote:I don't have that issue. I also do not have the external static port. Try disconnecting that and see what you get. I am pretty sure that my KAP140 has no plumbing for the static system and it has only one sensing port directly behind the controller.
I like the external static ports until it rains. It would be nice to have a way to switch between the internal and external ports.
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Lance Murray
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Re: Do I Need The GFC700?

Post by Lance Murray »

I suppose you could add an alternate static port.
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Tim
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Re: Do I Need The GFC700?

Post by Tim »

I never noticed my KAP porpoising until flying at higher (>10K) altitudes.
On the climb, it porpoises a bit, enough to be uncomfortable.
When climbing out over the Sierra Nevada mountains last week, the last 2-3000 feet of climb to 17.5 was hand flown.
When straight and level, it doesn't porpoise at all that I can recall.
Tim
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