Best location for Gretz pitot

[smithhb]

I am attempting to determine the best location for mounting my pitot on a RV-9. I would appreciate your suggestions. I am enclosing three pics and I have attached the inspection covers and tie-down ring for clarification.

Option 1: This is where Vans suggests installing the pitot and has holes in the ribs to this bay for routing lines. I feel the pitot head will be too close to the tie-down ring.

Option 2: This location is one bay outboard of an inspection panel and plenty far from the tie-down, but is located in the center of the wing (inboard to outboard). Not sure if that really matters.

Option 3: This location is also one bay outboard of the 3rd inspection panel and is the most outboard location. It will require routing the pitot tubing around the bellcrank.

I have just about ruled out Option 1 due to the close proximity of the tie-down. Option 2 or Option 3 are still possibilities.

 

[sportpilot]

gretz pitot

Cleve decided to locate the Gretz heated pitot on the rib outboard of the aileron bellcrank and access cover. You also need to mount the control circuit board. Cleve put the circuit board in the same bay with the aileron bellcrank fastened to the rib. We also were concerned about routing the tubing thru the bellcrank, so we cut a slit in the conduit and ran it down the conduit. We ran the power lead (high amps) separatly thru the rib gromets and under the bellcrank with the strobe power supply (the gray wire in the picture) We ran the circuit board wiring (low amps) down the conduit. We hope the tiedown wont interfer. Here are some pictures

Gretz heated pitot location N417CT

Heated pitot control circuit board location

More pictures here

 

[smithhb]

Claude/Cleve,

Your solution will require bypassing the bellcrank...I was hoping to keep that area as sterile as possible. It does look like you will have good access to the pitot through the inspection panel.

I just hate the idea of running anything underneath the bellcrank hinge.

 

[sportpilot]

Claude/Cleve,

I just hate the idea of running anything underneath the bellcrank hinge.

That picture is confusing with all that wire hanging out. Those are the wires that hook up to the control circuit board and they dont run down the wing. All the wiring is in the flexible conduit including the pitot tube. The only wire we have running under the bellcrank is the gray wire going thru the adel clamp. That is the strobe power supply and it in no way interferes with the bellcrank.

A better picture without all the clutter

This picture shows the pitot tubing going into the conduit. The gray strobe power supply can be seen running under the bellcrank. We moved the flexible conduit up one level so it wont interfere with the aileron push/pull tube running to the cabin. I hope this is a better picture of what we did.

 

[alpinelakespilot2000]

I put mine in the same bay as Van's.

Outboard of the aileron bellcrank has two disadvantages: (1.) You have to route around the bellcrank. (2.) Tie-down lines will usually come from more outboard locations and will thus have the potential to snag the pitot on the way to the tie-down ring.

The one disadvantage of Van's location is that it makes inspection/maintenance difficult unless you make another access panel. I made another access panel.

Good luck.

 

[smithhb]

I put mine in the same bay as Van's.

Steve,

Do you have any pics? I'm not aware of how Vans did his. I assume you put your pitot just inboard of the tie-down ring in the next bay. Like this:

I'm not sure why you would need to cut another panel?? It seems you are only one bay away from the bellcrank panel.

 

[alpinelakespilot2000]

Bret-
I don't have any pics handy right now. If I remember I can try to get some tonight. If you look on Van's drawings for the wing you'll see where they specify the pitot location. I put mine in the same bay, just closer to the outboard rib so that I could reinforce the pitot bracket by screwing it to the rib with some angle. But yes, it is just on the other side of the rib that is inboard of the bellcrank.

Technically yes, you could access it through the bellcrank inspection panel, but what I found problematic is how would you get two hands and two wrenches through there in the event you ever needed to service the pitot connections? At the minimum you'd have to take out the push tubes... even then it would be a challenge. Instead, I just followed the advice of my tech. counselor and made another inspection panel to match the three stock panels. Took about an hour. Now I have full access to those connections. It doesn't look bad either.

I think there are a lot of ways to skin this "where to locate the pitot" cat, so just use me as another example. Let me know if you have any other questions.

 

[sportpilot]

tie down

We considered the tiedown problem and are hoping it will not happen. For access to the pitot and the connections, we left sufficient wiriing and a loop of tubing floating inside the wing as per Gretz instructions. This allows you to take out the mast screws and slide the pitot out of the mast for dissconnecting or service. You dont need to go thru the access panel. To have access for the control circuit board we installed that in the same bay as the bellcrank. Mounting outboard of the bellcrank you dont have any interference with the bellcrank or push rods.

 

[alpinelakespilot2000]

Bret-Here's the picture of how I did it. Again, let me know if you have questions.

 

[rickmellor]

In my -7A I installed it on the outboard side of the bay outboard of the last inspection cover. I put a bend in the pitot line to go around the bell crank. The circuit board was installed in the same bay as the bell crank. I put the circuit board in an enclosure to give it a bit more protection.

-Rick