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TruTrak Gemini PFD Pirep / Feedback

Brantel

Well Known Member
This will be the first post of a series of Pireps on the new TT Gemini PFD.

First will come the desktop review and later once installed I will do an in flight review.

Here is the package and the unit as shipped:

rveglk.jpg


The cost to my door was $1320.00 direct from TT.

Included in the box is the Gemini PFD, a DB9 connector kit (solder type, not machined pins), the manual, and a micro fiber cleaning cloth. The unit is packed well with a film covering the screen. The packing media is cardboard, not foam.

Here is the unit out of the box and powered up. I have tricked it into thinking there is airspeed in order for the screen to display all the indications it can provide. It fits a standard 3.125" instrument hole. The unit looks to be about 3 3/8" square.

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Turned on its side this unit is very slim. The connector will stick out further than the unit will. It is only 5/8" deep less the connector and fittings. There is a raised round area that sticks thru the panel that is about 1/8" tall.

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The user connections are pretty simple. One DB9 connector for power, dimmer, GPS and TT proprietary communications. 2ea 1/8" NPT ports for static and pitot lines.

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First impressions are "This thing is light!".

The unit appears to be well made and the housing looks and feels like it is aluminum with a tough black finish that is textured so it does not show finger prints.

The pneumatic ports are part of the housing so there should not be any reason they would crack like some of the past products.

On the desk the screen powered up is very readable and the colors are nice with good contrast and color depth. The pics above look a little washed out due to the crappy camera in the Iphone. The real unit has better color than the images above suggest.

While the screen is small at a little shy of 3" dia, the information being presented is easy to see. I sat mine on the desk at three times my normal eye to panel distance for my plane and I could still read all the information well. The resolution appears to be quite high for this type of device.

As shipped the unit provides the following information:

Airspeed Indicator
Altimeter
Velocity Vector Display
Bank Angle Display
Vertical Speed Display
Track DG
Slip / Skid Indicator
Standard Rate Turn Indicator
Low Airspeed Warning
GPS signal status Indications
GPS Ground Speed Display

It is my understanding that a future firmware revision will also include the ability to switch from a Velocity Vector Display to a Pitch Attitude Display. As shipped this unit works much like the existing older TT ADI and EFIS products in that the instantaneous pitch indication is gyro based but over time it becomes vertical speed.

The manual is easy to read and since the unit is pretty simple, there is not much issue with getting it setup and running in no time. The entire user interface is thru the capacitive touch screen. The touchscreen works just like an Iphone or Ipad.

It is easy to adjust the altimeter setting, V-speeds, low-airspeed warning and they provide you the ability to adjust the DG in case of GPS failure.

Currently the only unit's available are KNOTS, FPM, and FEET. My understanding is that a future firmware upgrade will enable more units.

In the lower left corner, the unit displays airspeed or ground speed depending on the status of the GPS signal.

Along the bottom center the unit displays the DG reading or ground track depending on the status of the GPS signal.

The attitude indicator shows a standard rate turn indication that shrinks and grows depending on the airspeed. At zero airspeed this indication disappears. The vertical speed indications also change range depending on the airspeed indication. The faster you go, the more sensitive the indication appears.

The display brightness is great inside on the desk so I took it outside in direct sunlight and the unit performs very well due to the fact that it uses a transflective screen. While the touchscreen works like the Iphone/Ipad, the screen brightness in the sun blows the Iphone/Ipad out of the water. It does however suffer what all of the slick glass capacitive screens suffer from and that is reflections. This is easy to work around however since the screen is nice and bright in the sun. The off axis performance of the screen is where the screen starts to fall short. TT only recommends a maximum of 20° off axis viewing. The real world unit does start to get dimmer off to the side of center. It is hard to quantify this so take my word for it. Don't plan on mounting this way off center of the pilot and expect it to work very well.

Trutrak offers a backup battery (TCW Unit) for $200 or you can roll your own.
Trutrak also offers user firmware updates but it requires another one of their products to enable this feature @ around $150 otherwise you have to ship it back for updates. I would have preferred a simple boot-loader/updater that worked on the RS232 port but oh well....

The overall impression of this unit is that it will make a great backup EFIS for my panel. That is exactly how I intend to use it. More to come once I get it installed and fly behind it.....
 
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I'm envious......

My unit is currently on a tour of the US (no fault of Trutrak) and probably won't get it to mid week next week.

bob
 
Thanks for the pirep Brantel. I've been eyeing the Gemini PFD as a backup for my EFIS...but first I want to get my 9A flying.
 
Gemini ADI

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.
 
Really cool - I've been waiting for a review like this. Do they have a PDF of the manual up somewhere?
 
This will be the first post of a series of Pireps on the new TT Gemini PFD.

Trutrak offers a backup battery (TCW Unit) for $200 or you can roll your own.

Brian,

What are you going to use (or recommend) for a "roll your own" battery backup. I couldn't bring myself to spring for the TT battery. I installed my Gemini PFD yesterday and the unit looks great. I haven't flown it yet because we are having a "Little Debby" problem in our neck of the woods right now - Tropical Storm Debby, that is :)
 
Not sure yet. There are many examples of small backup battery setups here on the forum in the archives.

It will run on a 9v battery so even that is an option.

I may not even put a backup in my current panel as it is only the test bed for my Gemini that was purchased mainly for a backup for my panel retrofit that is coming up next spring.
 
Can this replace a DG?

As I understand it, if the GPS signal is lost (maybe a SPST switch in-line?), this can function as a replacement for a DG for ATC purposes? You can use the touch menu to set the heading readout to your compass just like a vacuum or electric DG?

I may not be understanding this correctly. Wonder if it precesses?
 
Yes, without a GPS signal the unit reverts to DG mode and acts just like a mechanical gyro. Yes it does precess but it does have a function to tweak most of it out. I tested mine and it moved about 5 degrees in 30 minutes.
 
I've been watching the reports start to come in on the Gemini. I was considering replacing my DG and AI with one. However, I'd want it to be the same as my DG and not slave to the GPS.

My two thoughts / questions. If I were not to connect to the GPS, what other capabilities do I lose?

Will the DG be configurable in the future ? This latter case is because I'm mostly interested in the Gemini AP to replace my aging (and ailing) DFC-250 unit.

At least for me, I have time to see where things go, since the AP is not scheduled until 2013.

Thanks for the PIREPs !
 
As far as I can tell you don't lose anything other than the groundspeed and ground track readings if you don't hook it to a GPS.
 
Glen, I'll bet you're caught 'twix and between. If you want the Gemini/autopilot version my guess is that you have to have the gps, too, since that's the way all the TT autopilots work, they're designed to track gps courses. Since it's not out yet it's not clear if you will be able to display heading (subject to "gyro" errors, needs to be reset just like a mechanical DG) while still feeding gps to the autopilot.
My question is, why? For instrument approaches, having ground track is far superior to having heading info. For VFR, who cares?
 
The short answer is that with all things considered, it probably does not matter. In the fullness of time, I'd like a simple glass panel. I'll either need to keep my old magnetic compass or get an EFIS with a Compass sensor
 
Got the Gemini PFD physically mounted tonight after removing some switches and dimmer knobs. Had to use an instrument hole punch to knock out the hole. Then do some mods to the panel support rib and relocate the switches ans knobs. Touch up paint the area scratched up by the punch.

Now all I lack is connecting the pitot and static and connecting a few wires and it will be installed.....test flight this week hopefully! I already have a spare static line and have quick connect fittings for the pitot so it should not take long to finish it up.
 
Install complete, ground checks complete. Test flight today or tomorrow....

My panel now looks like this:

Click for bigger pic...


Had to move a few things to make room for where I wanted the PFD.

On a side note:

You learn something new every day....Did you know that the 430W spits out magnetic heading that it gets from an ARINC connected EFIS as its ground track when the actual ground speed is zero? I did not until last night when I was curious to how my PFD was displaying the exact heading being shown on my Dynon.
 
aerobatic support

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?
 
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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It arrived!


FP27062012A0001A.jpg



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.
 
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.
 
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 :eek:

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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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Banking...

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?
 
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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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.
 
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. :confused:

brantel.jpg
 
It has something to do with the embedded data in the image because it was taken on an iPhone. The iPhones and iPads know what direction the camera was in when the pic was taken. This causes the iOS to flip it because I had to flip them for non iOS people.

It is kinda a pain in the rear!

I think I have em fixed now.
 
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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.

Bob is correct although TT has promised a firmware update to give the end user the option of the current velocity vector type display or a true attitude indication. Apparently they already have the hardware inside to pull this off.
 
It has something to do with the embedded data in the image because it was taken on an iPhone. The iPhones and iPads know what direction the camera was in when the pic was taken. This causes the iOS to flip it because I had to flip them for non iOS people.

It is kinda a pain in the rear!

I think I have em fixed now.

Ha! I learn something new everyday....here I thought I was the only one who was suffering from photo viewing dyslexia between different machines - thanks for the tidbit Brian!

Cheers,
Stein
 
Weight???

Anyone know what the Gemini PFD actually weighs? I may have overlooked it on the TT website.
 
I am thinking about a Gemini PFD as a addition to my RV6. If you have a IFR certified aircraft is the Gemini legal to replace the turn coordinator? I believe it would be but wanted to make sure. Its actually lighter then the TC installed and would provide a backup to everything else.

George
 
There is no such thing as an IFR certified experimental aircraft.

You either have the proper equipment or you don't.

Yes the Gemini PFD can replace the turn coordinator.
 
Just so this review is complete, after flying for a while behind the Gemini, i have the following observations. Nothing major but stuff to know and understand. Posted this on the TT forum and I am waiting on a response:

"Lucas,

I now have a few hours behind my Gemini PFD.

I have a couple questions/concerns:

The past few times I have turned on the unit sitting on the ground I have noticed that it settles to about 2-3degrees of right bank instead of the wings level indication. In the beginning it would always slowly go to wings level indication no matter what angle it was actually in. Over a period of like 10 minutes it eventually started showing wings level again like i would expect. Is this error temp related or???

The PFD is shows a slight offset on airspeed from my Dynon. Is there anyway that you can give the end user the ability to tweak the indication?

The PFD is indicating about 25-35 ft lower than my Dynon which just past an IFR static/alt/xponder test last month....it was dead on. Is there any way you can give the end user the ability to tweak the altitude indication?

I have noticed that in a sustained high rate turn that when I roll wings level that the PFD shows about a 5 degree roll angle error for a while till it settles out. Is there anything that can be done about that?

Today I was climbing out after take off and climbing at a 10 degree pitch up indicated on the Dynon and at 1000fpm on the Dynon. The PFD was showing 2----2 for the entire climb. I was not climbing at 2000fpm and I was not at 20degrees of pitch up. What gives with this indication?"
 
Thanks Brantel,

Can you update this thread when you get a reply? I'm thinking about buying one.
 
The 2-3 degree bank offset is temperature related. The gyros are calibrated at operating temperature so until they get fully up to temp there may be a slight offset. 2-3 degrees should be as much as you see on that.

What is the difference you see on the airspeed?

There isn't a way for the end user to change the altimeter calibration. Do you see this discrepancy all the time or only after power up? This could also be temperature related.

I'll look into the other two issues. The vertical speed display was tested extensively against several references so I'm not sure what's going on in yours.



Just so this review is complete, after flying for a while behind the Gemini, i have the following observations. Nothing major but stuff to know and understand. Posted this on the TT forum and I am waiting on a response:

"Lucas,

I now have a few hours behind my Gemini PFD.

I have a couple questions/concerns:

The past few times I have turned on the unit sitting on the ground I have noticed that it settles to about 2-3degrees of right bank instead of the wings level indication. In the beginning it would always slowly go to wings level indication no matter what angle it was actually in. Over a period of like 10 minutes it eventually started showing wings level again like i would expect. Is this error temp related or???

The PFD is shows a slight offset on airspeed from my Dynon. Is there anyway that you can give the end user the ability to tweak the indication?

The PFD is indicating about 25-35 ft lower than my Dynon which just past an IFR static/alt/xponder test last month....it was dead on. Is there any way you can give the end user the ability to tweak the altitude indication?

I have noticed that in a sustained high rate turn that when I roll wings level that the PFD shows about a 5 degree roll angle error for a while till it settles out. Is there anything that can be done about that?

Today I was climbing out after take off and climbing at a 10 degree pitch up indicated on the Dynon and at 1000fpm on the Dynon. The PFD was showing 2----2 for the entire climb. I was not climbing at 2000fpm and I was not at 20degrees of pitch up. What gives with this indication?"
 
Thanks Lucas on the bank angle offset. Your info confirms what I thought I was seeing.

The airspeed difference is minor < 5 knots

The altitude offset is constant.

Looking forward to the answers on the last two questions.


The 2-3 degree bank offset is temperature related. The gyros are calibrated at operating temperature so until they get fully up to temp there may be a slight offset. 2-3 degrees should be as much as you see on that.

What is the difference you see on the airspeed?

There isn't a way for the end user to change the altimeter calibration. Do you see this discrepancy all the time or only after power up? This could also be temperature related.

I'll look into the other two issues. The vertical speed display was tested extensively against several references so I'm not sure what's going on in yours.
 
Is the airspeed always ~5kts off or is it relative to current speed?

We verified the vertical speed again today using three methods; tested against our own EFIS, tested against the G3X display, and timed manually. It was right on target.

The only other thing I can think of on the vertical speed is that it is also temp related if this was on takeoff. The pressure transducers also have to get up to temp. I'll look further into this.
 
Is the airspeed always ~5kts off or is it relative to current speed?

We verified the vertical speed again today using three methods; tested against our own EFIS, tested against the G3X display, and timed manually. It was right on target.

The only other thing I can think of on the vertical speed is that it is also temp related if this was on takeoff. The pressure transducers also have to get up to temp. I'll look further into this.

Lucas, will have to fly again to be sure on the airspeed. I will scan the video I made as well and see how it relates on there.

I think the VS was temp related because later in the flight I could not get it to do the same thing again.

The ambient temp that day was around 80°F.

EDIT: I scanned thru the video I made http://youtu.be/KtlLPJzRXtg

You can see the airspeed difference is pretty minor on that flight. About 2 maybe 3 knots. I can live with that. I doubt two different sensors are going to get much better.

You can see the altitude difference varies from about 25ft to about 35ft.

The vertical speed seems to close on that flight.

I thinks some of the difference is that you guys have different filtering algorithms. That will make a difference.

At 6:20, 7:10 and 8:10 you can see the bank angle error that comes into play after an extended coordinated turn.

@ 8:30 I started doing some pretty good pitch changes and they were pretty close.

See you at Osh!
 
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I have a few flights with my PFD now and it is working properly. The airspeed, altitude and heading match perfectly with my AFS 4500 effis. The rate of turn and attitude indications also mimic the 4500. With my older and wiser eyes I am not sure if this unit would be large enough to be my primary instrument but as a standby unit it really puts a lot of information in a small space.
 
VSI

Can someone elaborate on how vertical speed is presented? Is it numerical? Can't seem to see it on the video...

I'm leaning toward the Gemini in my VFR RV4 .... no ADI whatsoever at the moment. Prefer an instrument that has actual ASI and altimeter.

Thanks
 
The Vertical Speed is indicated via the horizontal lines of the attitude display.

Since the attitude display is instantaneous gyro info that transitions over time to vertical speed, once you have a vertical speed established, the attitude display is vertical speed.

2vafins.jpg


The arrow in the above pic is pointing at the 1000ft/min up indication for VS. The scale of the VS indicator changes depending on air speed.

In the video, starting at around 8:35:00, you can see me do a few ups and downs and cans see how the VS indication works when compared to the Dynon.
 
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Since the attitude display is instantaneous gyro info that transitions over time to vertical speed, once you have a vertical speed established, the attitude display is vertical speed.

Not so. On the way home from OSH I discovered we have a static leak. Opening and closing avent would result in a 300 fpm climb/descent nearly instantly. Interestingly enough the Gemini will show a climb and keep showing a climb which tells me its just a VSI. As far as I'm concerned that's fine as long as one understands how the instrument operates. In a skidding turn it will flat out lie to you. 30 degrees of right bank with quite a bit of left rudder will show a left turn.
 
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