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  #21  
Old 06-27-2012, 12:37 PM
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alphaxray alphaxray is offline
 
Join Date: Apr 2012
Location: Beaverton OR
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Default aerobatic support

Quote:
Originally Posted by Stu McCurdy View Post
Back in early March while re-doing my panel to install my AFS5500, I installed a TT Gemini ADI as a backup attitude reference. I installed it between my backup altimeter and airspeed, so I did not need the PFD version.

The Gemini is everything I needed as a backup ADI and is as advertised. It is quite sensitive in pitch but serves as a good IFR platform. The small pitch lines do not present themselves until you have groundspeed and serve as a VVI in that one line up or down will deliver 500 ft/min climb/descent. It's heading reference along the bottom is actually GPS track and must have GPS input to work. While doing aggressive maneuvering or aerobatics it lags actual attitude and takes 3-4 seconds to catch up once maneuvering stops. It is an electrical instrument so you must have a battery backup in the system in case main battery/alternator/master switch is out.
In regards to doing aerobatics, I have another unit (Blue Mountain) that has the same problem. But what I'd like to see is a mode to switch the unit in while doing aerobatics, or will the new Gemini not have any "ill" effects if you do a lot of aerobatics?
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  #22  
Old 06-27-2012, 12:52 PM
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Brantel Brantel is offline
 
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The Gemini is all solid state. You cannot damage it with aggressive aerobatics.

What will happen with aggressive aerobatics is the indications will become incorrect similar to what happens when a mechanical AI tumbles.

All you need to do is fly straight and level for a few seconds until the Gemini catches back up to you.

All electronic gyros and accelerometers have a saturation limit. If you exceed this limit then there will be an error in the display but it will correct itself if you fly straight and level for a bit.
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Last edited by Brantel : 10-23-2012 at 05:41 PM.
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  #23  
Old 06-27-2012, 08:28 PM
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rleffler rleffler is offline
 
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It arrived!





I've been giving Lucas a hard time for a year, now I suspect I'll be on the receiving end until I get the RV-10 in the air. Unfortunately, it's about ready to head to the paint shop, so it may be another 4-6 weeks before I'll have a chance to light the panel up.
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  #24  
Old 06-30-2012, 01:38 PM
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Flew today with the Gemini PFD for the first time. This unit works very well. The screen is nice and bright and gets even better with direct sunlight. There are still some of those flat shiny glass reflections but not bad.

The indications were dead nuts on with the Dynon on all normal maneuvers. I am sure high rate acro Or excessive pitch and roll would cause it to tumble but normal burning holes does not.

I don't think I would have any issue keeping the dirty side down with this display in IMC.

I will try and take some video of it and the Dynon in the near future so you can compare.
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RV-10, #41942, N?????, Project Sold
---------------------------------------------------------------------
RV-7/TU, #72823, N159SB
Lyc. O-360 carbed, HARTZELL BA CS Prop, Dual P-MAGs, Dual Garmin G3X Touch
Track N159SB (KK4LIF)
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  #25  
Old 07-04-2012, 03:22 PM
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Got in the air with a camera for the first time since getting the Gemini PFD installed.

Here are a couple still shots showing the PFD in direct Sunlight this morning.
The second shot shows the off axis brightness. You can use the Dynon screens as a baseline. Those Dynon screens have the superbrite option.

Please do not pay any attention to my butchered up panel. It is only temporary till the G3X upgrade





Here is a link to a video on Youtube of me just messing around, flying around just burning holes in the air this morning. You can use the Dynon as a baseline. The Gemini has a transflective display. This really works well since the more sun that hits it, the brighter it gets. There are still some smooth glass reflections however. Not as bad as an Ipad but they are there.

Warning..Turn down your audio, it is nothing more than cockpit noise...
Somewhere around 4:40 I was yawing the tail around so you can see how the slip indicator works. Lots of turns both quick and extended. Around 8:40 I started doing some pitch oscillations so you can see how the attitude indicator works. It starts out as a typical gyro attitude display but then migrates over time to a velocity vector display. Sorry for the crappy video. It is the best the Iphone can do...

Click image for video. You can switch to HD inside the Youtube app.



Overall I think this thing works very well for the price, space, weight. I don't think any current Instrument pilot would have any problem at all keeping the shiny side up in IMC with this thing.
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Brantel (Brian Chesteen),
Check out my RV-10 builder's BLOG
RV-10, #41942, N?????, Project Sold
---------------------------------------------------------------------
RV-7/TU, #72823, N159SB
Lyc. O-360 carbed, HARTZELL BA CS Prop, Dual P-MAGs, Dual Garmin G3X Touch
Track N159SB (KK4LIF)
Like EAA Chapter 1494 on Facebook

Last edited by Brantel : 07-07-2012 at 05:50 AM.
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  #26  
Old 07-04-2012, 05:49 PM
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Thanks for PIREP Brian you know how to make it right
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  #27  
Old 07-06-2012, 07:19 PM
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Quote:
Originally Posted by Brantel View Post

Overall I think this thing works very well for the price, space, weight. I don't think any current Instrument pilot would have any problem at all keeping the shiny side up in IMC with this thing.
Your first and second shot look like about a 5 deg bank, but the Gemini is showing level. Is this my eyes or does it not register small banks?
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  #28  
Old 07-06-2012, 07:30 PM
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Brantel Brantel is offline
 
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The pics were taken on the ground. On the ground the Gemini will always slowly rotate till the horizon is level.
Notice the pitch is also centered and the Dynon is not. Same thing there.

That is how a velocity vector display works.

In the air it seems more natural.

The Dynon is a true ADHRS so it does not do that.

The bank angle is more like 2 degrees. In the air the Gemini shows small banks just fine.
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Brantel (Brian Chesteen),
Check out my RV-10 builder's BLOG
RV-10, #41942, N?????, Project Sold
---------------------------------------------------------------------
RV-7/TU, #72823, N159SB
Lyc. O-360 carbed, HARTZELL BA CS Prop, Dual P-MAGs, Dual Garmin G3X Touch
Track N159SB (KK4LIF)
Like EAA Chapter 1494 on Facebook

Last edited by Brantel : 07-06-2012 at 07:35 PM.
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  #29  
Old 07-07-2012, 01:17 AM
BobTurner BobTurner is offline
 
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To clarify, the gemini long term is a turn coordinator and a vsi. Short term it shows bank and pitch computed from accelerometers. So in this case the aircraft was not turning so the gemini shows wings level. But the taxiway wasn't quite level so the AI shows the wings not level.
I've flown the TT ADI which runs on the same principles. It is quite flyable but you do need to keep these differences in mind. Worst problem is that in nose high slow flight the ADI presentation shows nose level.
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  #30  
Old 07-07-2012, 01:29 AM
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Weird and not a thread drift but all your images on this thread are upside down on my iPad 1. Fine on my PC and obviously fine for everyone else. Just weird because I've been surfing VAF for years with my iPad and this is the only thread where the images are upside down.

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