Pitot in tail of Waiex
Posted: Sat Nov 30, 2019 9:45 am
by dbdevkc
I am still building, but I see in my factory supplied flight manual in the Operating Checklists/Walk Around Inspection, #2 (which is the tail section): “c. Inspect/Install pitot/static tube (Waiex).”
Was this always an option on the Waiex? The only one flying like that that I am aware of is Kip Lorie’s Waiex, I also know that Bryan’s build has that also. But I was pretty sure that it was a custom build option.
Re: Pitot in tail of Waiex
Posted: Sat Nov 30, 2019 12:03 pm
by Bryan Cotton
I have no idea if it was ever an official option. One less thing to connect at the wing root is a bonus though. And if my tube is ever destroyed, it is easy to pull it out and put another in.
Re: Pitot in tail of Waiex
Posted: Sat Nov 30, 2019 12:55 pm
by Bryan Cotton
In this old Xenos article it looks like the factory ship has a tail mounted pitot or total energy probe.
https://www.sonexaircraft.com/kitplanes … l-wonders/
Re: Pitot in tail of Waiex
Posted: Sat Nov 30, 2019 1:20 pm
by scotttro
You know, that brings up an interesting question: If a pitot/static works in the tail, might an LRI probe?
Re: Pitot in tail of Waiex
Posted: Sat Nov 30, 2019 2:06 pm
by Bryan Cotton
I’d say no. Doesn’t an LRI measure delta- pressure between the top and bottom wing surfaces?
Re: Pitot in tail of Waiex
Posted: Sat Nov 30, 2019 6:51 pm
by GordonTurner
I would say it would. The probe isn’t sampling pressure above and below the wing, but the change in relative pressure between a pitot at (roughly) zero degrees incidence and one at minus 45 degrees incidence. The two probes could be anywhere.
Gordon
Re: Pitot in tail of Waiex
Posted: Mon Dec 02, 2019 1:25 pm
by Onex107
An AOA or LRI should be mounted 90 degrees to the wing, where ever it is mounted. It is actually measuring the angle of attach by using differential pressure above and below. I presume you are talking about mounting the sensor on the “Y” tail, at an angle. Mounted vertical to the wing it might work, if the wing doesn’t blanket the tail at a stall angle of attack. It’s an excellent instrument to add. It will improve your landings. The plans are on the internet.
Re: Pitot in tail of Waiex
Posted: Mon Dec 02, 2019 2:06 pm
by racaldwell
I built a diff. pressure LRI for my RV6. ( I mounted the tubes in a hollow windsurfing fin mounted to the bottom of the wing.) It works well. However, you have to look at it for it to have any value. I just can not look at it while very close to the ground and slow airspeed because all my attitude queues are outside the window. I have the guage mounted high on the panel just to my right but just don’t feel comfortable taking my eyes off the runway area. In hindsight, that project was a waste of time for me.
I do have a TE probe with pitot and static mounted to the tail of my Xenos. The LRI probes would work there just fine.
Rick Caldwell
Xenos 0057
Re: Pitot in tail of Waiex
Posted: Mon Dec 02, 2019 4:17 pm
by Rynoth
Rick, that’s a good point on the location of the instrument, as it’s only useful if you can see it in the phases of flight where it’s useful. On top of the dash can be a good place to put it if it doesn’t otherwise obstruct your view (varies for different aircraft of course), but I’ve found mine to be very easy to reference in my Waiex by mounting it directly in front of me near the top of the instrument panel, essentially as a primary instrument, right next to slip/skid indicator which is equally important in slow flight.
Re: Pitot in tail of Waiex
Posted: Tue Dec 03, 2019 1:28 pm
by Onex107
Mine was a late addition so it’s not in the panel. It’s about like Ryan’s but on top of the panel down next to the windshield as far as it will go. Not pretty but easy to watch as you land. Built from 1/4 inch alum scrap and plumbed to a $60 differential gage. Mounted on the inspection cover under the left wing. Adjusted to stall at the red.
Re: Pitot in tail of Waiex
Posted: Wed Dec 04, 2019 11:07 am
by Spaceman
Do any of the commonly used iEFIS type glass panel systems accept inputs from an LRI so you can display the info on the screen instead of the analog gauge? I haven’t really put much thought into avionics at all yet but I bought an LRI kit and put it in the left wing inspection panel and ran the tubing to the wing root way back when I built my wings.
I figured I’d decide how to use it later but if it could be integrated into a glass panel that would be pretty slick. Then again the analog gauge is a good backup if the panel fails; you could probably fly with nothing but the LRI if you’re VFR…
Re: Pitot in tail of Waiex
Posted: Wed Dec 04, 2019 12:47 pm
by Area 51%
Do any of these LRIs offer any kind of audible output? I don’t suppose it would do much good with everyone wearing noise cancelling headphones these days.
Re: Pitot in tail of Waiex
Posted: Wed Dec 04, 2019 3:10 pm
by T41pilot
Grand Rapids Technology units have an Angle of attack indicator that may help you out. They also have audio warnings that can be downloaded for the efis. A stall warning may be one of them. I purchased a GRT sport EX system but have only scratched the surface on wiring and learning all the stuff it can do. I’m still designing my panel and have a spot leftover on the right side to figure out yet. Seat heater switches and ELT indicator fit under the radio stack. Thinking about trying to get a kindle running as a second display using the GRT remote app.
Re: Pitot in tail of Waiex
Posted: Wed Dec 04, 2019 3:35 pm
by Spaceman
Looks nice so far! Now I’m getting way off topic but where are you putting your pitch trim knob? So far that’s all I have on my panel and I just copied the factory plane’s location in the upper left corner of the panel.
Re: Pitot in tail of Waiex
Posted: Wed Dec 04, 2019 5:38 pm
by T41pilot
Well it may be over the top and just another bell or whistle, but one of the rocker switches on the left side of the panel will be operating a linear actuator to be positioned under the seat pan for electric elevator trim. I have DIY indicators for flap position and elevator trim position next to the switches. I looked at hat switches for the stick but they were crazy expensive. I don’t remember the price exactly but I think my rocker switches were under 10 bucks. I just didn’t want the big red knob on my panel. The bargraph is a DIY indicator for fuel quantity. It will just act as a backup for the EFIS indicator. I’ll use a probe for the bargraph and the EFIS can calculate quantity using fuel flow as well.
Re: Pitot in tail of Waiex
Posted: Wed Dec 04, 2019 8:01 pm
by Spaceman
Oh wow that’s awesome! Ok so going even further off topic, if you’re putting the actuator under the seat, are you going to build in some kind of access panel in case you have to get at it later?
I want to eventually put in a simple autopilot but I haven’t yet addressed how I’d ever access the aileron servo once the seat pan and floor are both riveted on. I’m not sure why they made the seat bottom so permanent on the B model compared to how the legacy seat is attached!
Re: Pitot in tail of Waiex
Posted: Thu Dec 05, 2019 11:01 am
by Area 51%
For what it’s worth, seems I remember someone installed their roll servo in one of the wings out by the belcrank.
Re: Pitot in tail of Waiex
Posted: Thu Dec 05, 2019 11:45 am
by OneTallShort
Area 51% wrote:Do any of these LRIs offer any kind of audible output? I don’t suppose it would do much good with everyone wearing noise cancelling headphones these days.
The MGL iEFIS system will do an LRI with audio output which can be fed through the intercom into your headset. For at least the iEFIS lite which I have, you need to purchase the iEFIS Extender which adds AOA, 4 additional RS-232 Ports and analog inputs for $250
http://kb.mglavionics.com/article/AA-00 … atics.html
I’ve got a drilled out rivet on my Legacy Sonex wing above the plans built Pitot-static tubes. Hasn’t flown yet though…
Gregg Short
Sonex 715
Re: Pitot in tail of Waiex
Posted: Thu Dec 05, 2019 12:46 pm
by GordonTurner
Roll Servo in wing (picture from underneath, main spar at top of photo)
Re: Pitot in tail of Waiex
Posted: Thu Dec 05, 2019 1:09 pm
by racaldwell
For the trim knob, I have installed a vernier that is normally used for the prop governer. I haven’t flown yet but it seems to work fine in the hangar. It is located by my left thigh.
Rick Caldwell
Xenos 0057
Re: Pitot in tail of Waiex
Posted: Thu Dec 05, 2019 1:25 pm
by Spaceman
GordonTurner wrote:Roll Servo in wing (picture from underneath, main spar at top of photo)
Ah that looks nice. If I hadn’t already closed up my wing that would be a great solution! I don’t think I could get all that installed through the inspection panel, and I definitely don’t want to drill out and remove the whole wing skin. At this point I guess it would be less effort to put in some kind of access panel either in the floor under the seat, or just on the seat pan itself. I haven’t planned that far ahead.
Re: Pitot in tail of Waiex
Posted: Thu Dec 05, 2019 5:07 pm
by T41pilot
Chris
I plan to use either the rear spar carry through or the aft lower seat support as a mounting position for the linear actuator. Since the seat back is hinged, it can be removed for servicing that area. Your upholstery solution would have to accommodate a seat back removal. I also contemplated having an inspection plate in the seat bottom as well. Unless you suffer from the princess and the pea syndrome, you should never feel the mounting screws through the upholstery.
Re: Pitot in tail of Waiex
Posted: Mon Dec 09, 2019 7:06 pm
by thomas
I’m really intrigued by what Kip and Brian have done with moving the pitot to the stabilator. If there are no performance issues with this modification, I would like to do the same with my build as I have visions of damage to the wing-mounted pitot from hanger rash.
I’ve tried searching the forum but I don’t see where Kip may have shared if there are any attitudes where the prop wash alters the indicated airspeed. If somebody who’s asked Kip the same question could chime in or point me to the right thread, that would be much appreciated. I know the Xenos has a similar setup but, because it has larger stabilators, it seems there is less chance of prop wash interference than with the Waiex.
Thanks!
Paul
Re: Pitot in tail of Waiex
Posted: Mon Dec 09, 2019 9:29 pm
by N111YX
Paul, the only time I have an error in airspeed reading is waiting to takeoff with a slight crosswind and the propeller blast gets blown over into the pitot. It may show 15-20 mph when standing still. Once I’m rolling, there is no adverse effect. I have no regrets in putting it in the tail.
There may be picture on this website from long ago but my pitot tube is removable and slides into a phenolic block that is riveted to the outermost rib. I tapped the phenolic for a nylo-seal pitot line.
By the way, my static system consists of a 3/32 inch hole drilled into the static port shipping plug on the back of the Dynon. Pretty simple and works great. Altitude is within 50 feet of an IFR system (formation check) and airspeed is within 2%.
Regards,
Re: Pitot in tail of Waiex
Posted: Mon Dec 09, 2019 9:40 pm
by N111YX
A little video from a few years ago…
https://www.youtube.com/watch?v=kKxCEWkGX34
Re: Pitot in tail of Waiex
Posted: Mon Dec 09, 2019 9:47 pm
by Bryan Cotton
Here is the original thread with Kip’s pictures.
viewtopic.php?f=15&t=927
I copied what Kip did very closely. There are pictures in my build thread.
Re: Pitot in tail of Waiex
Posted: Mon Dec 09, 2019 9:56 pm
by N111YX
Good find, Bryan. I thought those pics were here:)
Bryan Cotton wrote:Here is the original thread with Kip’s pictures.
http://www.sonexbuilders.net/viewtopic.php?f=15&t=927I copied what Kip did very closely. There are pictures in my build thread.
Re: Pitot in tail of Waiex
Posted: Tue Dec 10, 2019 12:25 pm
by thomas
Thank you, Kip and Bryan!
The crosswind scenario on taxi sounds manageable. I’ve been saving photos of both of your builds but your feedback was the confirmation I needed to move in this direction.
Thanks for blazing the trail and sharing the knowledge!
Paul
Re: Pitot in tail of Waiex
Posted: Tue Dec 10, 2019 4:21 pm
by Area 51%
For what it’s worth…I also copied Kip and Bryan and have a Waiex you can put an eye out with.
Can’t post here, but PM me your email address and I’ll send you pictures of my installation. Biggest difference between mine and theirs is I used rivnuts and screws to attach the block.
Re: Pitot in tail of Waiex
Posted: Tue Dec 10, 2019 4:49 pm
by thomas
Fantastic - thank you! PM sent. Paul
Re: Pitot in tail of Waiex
Posted: Tue Dec 10, 2019 5:11 pm
by Bryan Cotton
I regard rivnuts as the work of Satan, so I used nutplates instead.
Re: Pitot in tail of Waiex
Posted: Tue Dec 10, 2019 5:26 pm
by Area 51%
If I had your skill for drilling out rivets, I would have gone with nutplates too.
Re: Pitot in tail of Waiex
Posted: Tue Dec 10, 2019 6:26 pm
by Bryan Cotton
I’ve had lots of practice, meaning I screw up a lot.