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TS Flightlines/Aircraft Specialty Red Cube install Kit

mfleming

Well Known Member
Patron
Just wanted to share the install I just did on my Red Cube.

After looking at numerous different installs, I decided to go with the install bracket by TS Flightlines/Aircraft Specialty. A nice turnkey option that is very well documented.

The core of the kit is a beautiful custom bracket and hose. The install has you move the outlet from the bottom of the fuel servo to the top which I think is much cleaner. and also remove the 90° fitting from the flow divider and install a straight one.

I was worried the bracket bolt would be a difficult chore but ended up being a non issue and the install was a breeze. It's nice to have this job behind me :D
 

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If you don't mind disclosing, how much is the kit. I think Tom told me a while back but I can't remember. Finally getting ready for my panel upgrade and it will include a red cube install.

Thanks
 
Very clean install but I thought there was a requirement that the Red Cube be installed with the wire facing up. Has this been changed or has experience proven that it is not needed?
 
Danny---if the wire is installed UP, what happens if you make a 90* bank, or fly inverted? The wire wont be up anymore. And YES----the transducer still reads JUST FINE.

Tom
 
If you don't mind disclosing, how much is the kit. I think Tom told me a while back but I can't remember. Finally getting ready for my panel upgrade and it will include a red cube install.

Thanks

Good morning.

Here is a link to the ordering page with more information.

http://aircraftspecialty.com/rv-7.html

It runs between 299.95 and 364.95 depending on if you want steel or stainless fittings, and also if you want the hose in standard or integral firesleeve.

Happy building,
Steve
 
Michael, you probably saw this already but just in case, there appears to be a washer lying below the hose in the second pic.
 
It's great!

I really enjoyed the support (as always) in working with Steve to get this kit installed in my plane. This kit made everything very tidy and professional looking. The red cube is very secure and the hose routing is great. Beautiful work! Highly recommended to other builders.
 

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Michael, you probably saw this already but just in case, there appears to be a washer lying below the hose in the second pic.

Yes, I almost snapped another photo but I thought…we’ll see if anyone notices…good job ;)
 
Steve, is this available for RV10? cannot find it on your website for RV10 product category. Thanks.

Unfortunately this bracket can't be used on the RV10 due to the location of the flow divider on the case. On the -10 we run the red cube between the mechanical fuel pump and servo as our standard installation. (similar to the -14)

Alternatively, here is an image of something else that can be done. You can use the stock length hose from the servo to the spider and instead attach it to the red cube. Then you run another shorter hose between the red cube and the spider.

attachment.php


Steve
 

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keep an eye on the fittings for any signs of distress from thermal expansion. short straight connections on a hot engine with cool fuel get my attention.

component center to center distance appears to be 3 inches. hot engine 230F and cool fuel 30F is a temp delta of 200F. thermal expansion of alum ~ 13E-6 in/in/F.

(3)(13E-6)(200F) = .008 inches movement and the stress will be on the fittings because the other components are robust.

it will move a delta of this amount with each thermal cycle. is this movement enough to cause any concern? only an analysis can determine that. the obvious location for routine inspection is the threaded elbow connection to the red cube for any signs of leakage.
 
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@Steve,

Throw in the fact that the structures aren’t that rigid, especially relative to each other, stresses can get very high very fast. I started a thread inquiring about minimum tube length and didn’t get an answer. Can only assume a minimum length => 1/2 of minimum supported length. Can only assume that those calcs and related standards assumed perfectly rigid attach points. Assumed Delta T? Who knows?

Short and straight are a recipe for bad things. If you know more, mind sharing here or at:

https://vansairforce.net/community/showthread.php?t=199383
 
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Someone asked in a PM if this was the new or old bracket. I don't know but here's a photo of it for those that are interested
 

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keep an eye on the fittings for any signs of distress from thermal expansion. short straight connections on a hot engine with cool fuel get my attention.

component center to center distance appears to be 3 inches. hot engine 230F and cool fuel 30F is a temp delta of 200F. thermal expansion of alum ~ 13E-6 in/in/F.

(3)(13E-6)(200F) = .008 inches movement and the stress will be on the fittings because the other components are robust.

it will move a delta of this amount with each thermal cycle. is this movement enough to cause any concern? only an analysis can determine that. the obvious location for routine inspection is the threaded elbow connection to the red cube for any signs of leakage.

So the straight fitting off the flow divider connects with the 90° fitting attached to the red cube... Is this the area of concern?
 
I was worried the bracket bolt would be a difficult chore but ended up being a non issue and the install was a breeze. It's nice to have this job behind me :D

Not sure how you did it, but installing that bolt and safety wiring it was a PITA.
 
I started playing with this idea about 9 years ago, after doing some installs. Originals had 2 hoses, 1 generally very short and 1 longer. The short hose was always wrong. Some of you may remember. So in order to simplify the install, I came up with a similar system that was used on the AFP Purge valve, that some of you had. Credit goes to Don RIvera on that item.

I can only tell you that in 9+ years of installing the transducer this way, we have not had a structural failure. Even in the past, before the bracket, a bunch were flying with no issues. Yes-----I'm sure there is all kinds of math to say this doesnt work. I also remember the single bullet theory.

And if someone has a single hose solution, universal and adaptable to most 4 cylinder Lycomings, no matter what sump and servo, I'll be glad to listen.

Anyone recognize this?

Tom
 

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Not sure how you did it, but installing that bolt and safety wiring it was a PITA.


The bolt instal was a little fiddly but not bad. As far as safety wire...The original bolt from Lycoming wasn't safety wired, I just used an internal star lock washer.
 
Steve---the 90* elbow is a steel or stainless fitting---depends on what kit is purchased. IMHO, better than aluminum AN fittings that are used alot. We dont, but other types of installs have.

Tom
 
I didn’t use their bracket, but definitely their hoses. Steve was great to work with.
 

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Someone asked in a PM if this was the new or old bracket. I don't know but here's a photo of it for those that are interested

This is the new style bracket......... based on feedback, we made numerous modifications. Same basic design but a bit less bulky and easier to install than version 1 bracket.

Steve
 
I used their hoses but installed the cube after the fuel servo and in a horizontal orientation on my -540.
 

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I don't have the nice bracket, but this is the way my red cube is mounted and after 340 hours, it's done just fine. I love the fact that after I calibrated the K factor, it's now within a tenth or two of the actual fuel level every time after refueling. I can't really trust the fuel level sensors, but I can trust the calculated levels within that tenth or two. By the way, it was Tom's idea when I did it based on others who have done this.
 
Hi Dan---yes I DO remember---and I have the install pics. My point was the wire isnt facing UP---well I guess if you make a left 90* bank it would be--
and it has a very short hose with a 90* hose end, and a 45* inlet fitting on the transducer. Kinda 'violates' the parameters that EI has, but has worked for a long time.

Guys---keep in mind that that stock installs on the RV10 and RV14 both violate EI's recommendation too---but work just fine.

Tom
 
Hi Dan---yes I DO remember---and I have the install pics. My point was the wire isnt facing UP---well I guess if you make a left 90* bank it would be--
and it has a very short hose with a 90* hose end, and a 45* inlet fitting on the transducer. Kinda 'violates' the parameters that EI has, but has worked for a long time.

Confirmed, seems to be quite accurate at all flows.

Guys---keep in mind that that stock installs on the RV10 and RV14 both violate EI's recommendation too---but work just fine.

The reason is obvious when you take a red cube apart.

Fuel spins a turbine with flow at a tangent to its circumference. That means the inlet and outlet are offset to one side of the turbine chamber. With the wire up, the ports are at the top. With the wire on the side, the port flow is vertical. Neither position can trap any significant amount of vapor. However, I'll venture a cube installed upside down, wire on the bottom, will lose accuracy because it will trap vapor in the top of the chamber, and the paddle wheel won't spin consistently.

Simple bracket behind cube. It's not just hanging in the hose, although a lot of them seem to be fine that way.
-
 

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...
Simple bracket behind cube. It's not just hanging in the hose, although a lot of them seem to be fine that way.
Here's how I installed my "red cube." It is in about the same place recommended on the RV-14 plans, although I did bolt mine to the engine. I've read that this might not be the best idea due to the transmission of vibrations from the engine to the fuel flow mechanism.

So far it's reading accurately at about 100 hours of flight time.

img_1554.jpg

... and a few more pictures:

http://www.rv8.ch/red-cube-fuel-flow-transducer-installation/
 
LOL---Hey Mickey----another 'not to instructions' install that is working just fine. Last I heard, this was experimental aviation, so playing out of the box--within reason and good testing--is pretty normal.

Nice Job.
Tom
 
Just like was mentioned, the cube in my RV-10 is installed before the mechanical fuel pump. Not recommended. Only downside I and others have seen is an exaggerated flow reading when the boost pump is on. Not a big deal.
 
Matt---The RV10 was originally designed to have the transducer in the tunnel by Vans engineering. Its proven to be a reliable install, despite it being in "violation" of EI's 'recommendations' of after the last fuel pump, and a section of straight line on either side of the cube. Well, I guess the length of tube (by the plans) before its curves up to clear the heater tubes and connect to the firewall bulkhead fitting could be viewed as straight. (Just because with a hand bender and flaring tool the flare would be about 1.75-2.0 from the bend).

Tom
 
Matt---The RV10 was originally designed to have the transducer in the tunnel by Vans engineering....despite it being in "violation" of EI's 'recommendations' of after the last fuel pump...

To be fair Tom, such installations are typically not accurate with the boost pump on, which is why a cube mount near the divider is a better bet.

I might have placed mine there, but already had a purge valve in the space.

I like Mickey's mount too. It's downstream from both pumps, and well inboard of the exhaust headers, i.e. limited fuel heating.
 
LOL--Dan---I wasnt really advocating for or against the Vans RV10 install. My point was it too 'violated" EI's recommendations. You and I went thorough that a long time ago.
My Comment was mainly for those that wanted to floow to the letter of EI's 'recommendations'. I dont believe they were thinking of the experimental guys when they developed the cube.

Tom
 
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