macrafic

macrafic

Well Known Member
I was wondering if anybody had done a detailed comparison between, what appears to be, the two leading candidates for heated pitot tubes (I'm sure you all will let me know if there are other viable candidates!). That would be the Dynon and the Gretz (now markted by Angus Aviation).

They are both the same price and the electronics seem to be similar.

The Dynon comes with the AOA port. This would be a key factor if you are going with the Dynon glass. On the other hand, if you are going with the AFS glass, I know they integrate their own, but separate, AOA. Don't know if either AOA works with the competitors glass.

The Gretz comes with a 3-light panel marker to let you know the current operating status of the pitot.

Anybody have experience with either of these and can chime in on quality, advantages, disadvantages, opinions, etc.?
 
Problem with Gretz & Falcon heated pitot

I installed a Gretz heated pitot during construction of my RV9A but added a switch on the panel to activate it,; this in addition to the automatic features. I have switched it on for maybe 15 minutes in 2 years of flying. However the other day, I discovered that due to a short probably on the board, the tip of the pitot tube had "melted" & it could not pass IFR inspection. The functions of the board are just too complex in my opinion. That is why I installed a switch.
I didn't want to install another Gretz, so I ordered a Falcon heated pitot from Spruce. However, during installation of the Falcon, I found that the only thing holding the entire pitot tube together was a piece of 1/4" threaded aluminium tubing and it broke with very little pressure. :( I am now trying to fashion a replacement for the aluminium tube and will try to use brass this time.
I like the simplicity of the Falcon, just switching on the unit and bypassing thermistors etc. but the design is really not robust! Oh, btw, the fit of the Falcon in the Gretz mast is not perfect either but with some careful grinding this should be OK.
I will let you know how the new tube works out.
 
dynon user

I have the dynon tube. 1 winter of use under my belt. I keep the plane in an insulated but unheated hangar. Last year on one of the coldest days the tube developed ice on the inside. I realized this on the takeoff run as I had no airspeed. I turned on the heat and it failed to clear the ice even though it was working. My understanding is that these units only deal with ice near the tip that would be accumulated in flight, not condensation that could accumulate near the back. I removed the ice with a heat gun and blowing through the tube from the back, never happened again. Other than that, it works great!
 
andrew phillips said:
... I turned on the heat and it failed to clear the ice even though it was working. ...
Click to expand...

Andrew, how long did you give it?

I could easily imagine that it would take minutes for enough heat to reach the back of the tube to melt ice that's already accumulated there, but I would be surprised and concerned if it was really incapable of melting it given enough time. I'm very curious to know.

And generally (in response to both Cleve and Andrew) a key benefit of these regulated tubes is operational simplicity: as soon you start up, you turn on the pitot heat and forget it, even if you don't suspect ice. In Andrew's case that may also have given the tube enough time to melt the ice before takeoff. Or maybe not, but that would be the idea.
 
Dynon

I have the Dynon. It has plugged up twice in IMC -13c (two completely different flights). Stayed plugged until I descended to above freezing. I called them and they worked with me very well. I have installed a replacement Dynon but have not had it back into the same conditions so I can not say if it is solved. With a TT autopilot you lose the alt hold ability as the indicated airspeed drops to zero. It was interesting to watch the calculated wind speed on the GRT go from a 4kt tail wind to 140kt tail wind as the airspeed died off. The windshield was clear and the wings and tail were also clean. The pitot heat was checked and on before the flight. The blocked tube came after being in IMC for about an hour at 15k.
Floyd
 
To answer Roee's question. I flew for about 1/2 hr with the thing on and it did not fix the problem. It was about -22 F when I took off. I noticed the blocked pitot immediately after wheels up and turned on the heat. I continued flying for about 1/2 hr near the airport hoping it would clear... it did not. I landed using the gps to give me ground speed.
 
andrew phillips said:
To answer Roee's question. I flew for about 1/2 hr with the thing on and it did not fix the problem. It was about -22 F when I took off. I noticed the blocked pitot immediately after wheels up and turned on the heat. I continued flying for about 1/2 hr near the airport hoping it would clear... it did not. I landed using the gps to give me ground speed.
Click to expand...

Not the answer I was hoping to hear...

So I wonder what Dynon would have to say about it. I wonder whether your tube is defective, or if they are all just a bit too wimpy for those conditions?

In any case, I still think the best way to operate the tube would be to turn it on immediately after engine start, so it's heating up for those few minutes during taxi. It might not have made any difference in your case, but then again it might have. It would at least have a better chance. I suspect that the back of the tube could get quite a bit warmer on the ground in relatively still air than it would in flight with that -22 F air blowing across it at 170 knots carrying away that heat. Just a thought.
 
roee said:
\In any case, I still think the best way to operate the tube would be to turn it on immediately after engine start, so it's heating up for those few minutes during taxi. It might not have made any difference in your case, but then again it might have. It would at least have a better chance. I suspect that the back of the tube could get quite a bit warmer on the ground in relatively still air than it would in flight with that -22 F air blowing across it at 170 knots carrying away that heat. Just a thought.
Click to expand...
Yeah, pitot heat is an anti-ice system, not a de-ice system. It is designed to prevent ice from forming. In other words, you turn it on well before you have ice, rather than waiting until you have ice before you turn it on. I turn my pitot heat on for every flight, unless I am 100% sure that I will be below the freezing level for the whole flight - i.e. low altitude flights in the hotest part of summer.
 
I'm not sure about the anti-ice/de-ice comment. My only experience to relate was in a Cessna 414 as a passenger in the right seat. At around 17K we entered IMC and in a few minutes I called out the pilot that he had lost the ASI.

Pitot heat turned on and in a few minutes ASI came back on.

I'm going to put pitot heat in m RV-10 and I want to make sure that, if I were to forget pitot heat and needed it, I wouldn't have to wait to get on the ground for it to do any good.

Maybe the "fire and forget" versions of these things aren't such a good idea after all.
 
Richard,

That is one of the benefit's on the Gretz pitot. Turn it on and forget. The control module will cycle the pitot based upon temperature of the pitot.

There are hundreds of the Gretz pitots installed. One failure, while significant to that individual, is not indicatitive of a product issue.

I will admit that I discovered a manufacturing defect in mine while installing and test the pitot. While I purchased mine from Warren, Andrew at Angus took care of the warranty replacement at no charge.

For those thinking about a Vertical Power unit you can eliminate the led module and have the annunciators appear and alarm on the VP-200.

bob

 
Gretz

I have flown in IMC and picked up a lot of ice once. (about 1/2 clear ice on wing LE and 3/4" on my prop blades.) The pitot was on and did fine. Dealing with a heavy airplane, ice on the windsheild, etc. it is not a good thing to have to worry about whether a pitot has enough heat to clear itself.
 
I have been flying with the Gretz for just about a year now. All of my phase 1 flying was in MN in November and December, so saw plenty of cold temps, but, of course, no IMC. Now that I am in FL and have taken some trips, I absolutely love the way it works. I do have the VP-200 and have it set up so that the pitot heat is on for every flight. It comes on in the After Start mode and stays on until the Postflight (after engine shutdown) mode. I can see it cycling on and off at high altitude when outside air temps get into the high 40's. As Bob L noted, I don't have the three panel lights because Vertical Power annunciates the modes. Very cool.
I have not flown in any icing conditions, but am confident in the system.
 
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