Wing Ribs

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Posted

I am going to be installing fuel level indicators on my tanks (clear tube style). However the previous owner fiberglassed the butt rib on the wings. 

So my question is, are the butt ribs on the wings and the butt ribs on the fuse the exact same cutouts? I need to get through the fibreglass and remove as much of it as I can to expose the tank. 

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Posted

The MK IV Avids I've had did not use a butt rib on the wing.  The fuel tank finishes off the end of the wing.  Got a picture of yours you could post?   JImChuk

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Posted

The MK IV Avids I've had did not use a butt rib on the wing.  The fuel tank finishes off the end of the wing.  Got a picture of yours you could post?   JImChuk

crap now that I think of it, that may be my case also. I'll take a much closer look on top and bottom of wing. But then again if that's the case I won't need to remove fibreglass to expose the tank for installing sight tubes. Correct? 

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Posted

The Avid Magnum was the only one that I know of that had fiberglass ribs on the fuselage, although these may have been added to some other Avids - If you are looking thru a wooden rib and seeing fiberglass, then you are looking at the end of the tank.  Kitfox used wood ribs both on the fuselage and on the root end of the wing with or without wing tanks.  EDMO

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Posted

Here is a picture of the butt end of one of my Avid MK IV wings.  There is a partial rib behind the rear spar, but only the fiberglass fuel tank in front of it.  JImChuk

Photo0045.jpg

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Posted

Okay thanks a lot guys. I took a closer look and it appears just as you stated. 

My model 2 Kitfox had the butt ribs with wing tanks so I think that confused me believing they'd be the same. 

I was wondering why the previous owner had a horribly cut square cut out in the fabric that didn't show anything, even before painting. Picture attached. 

Ive been posting a lot because I just want to be sure. After finding some worrisome work done to her I am looking everything over with a magnifying glass and getting all the direction I can. I've had to replace and repair nearly everything. Garbage bag ties used as cotter pins and wiring tie downs don't sit well with me. Oh and the 4 different colored wires all twist tied together with house merets that power the fuel pump....no thank you. 

IMG_5630.JPG

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Posted

Keep posting - We love photos - Bad work can be just as informative as good work.  Looks like you will know a lot about the plane before you get thru fixing it.  If you need answers or opinions, you can probably get more than you need on here - just pick out the one that suits you.  :BC:   EDMO

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Posted

Wow scary stuff. I have respect for anyone who's built a plane but some people really shouldn't. Remove a big strip of fabric where that square is. The bigger the spot the easier it is to see the fuel in the tank. There is a butt rub but it's on the fuse end and easy to modify. Your gonna want parked and inflight marks in gallon increments at some point. I love knowing exactly how much fuel I have at any given point without guess work and Hobbs times. 

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Posted

Joey is right - If the guy didn't paint the end of the tank, or a least left an area without paint, you should be able to see the fuel in the tank.  EDMO

Wow scary stuff. I have respect for anyone who's built a plane but some people really shouldn't. Remove a big strip of fabric where that square is. The bigger the spot the easier it is to see the fuel in the tank. There is a butt rub but it's on the fuse end and easy to modify. Your gonna want parked and inflight marks in gallon increments at some point. I love knowing exactly how much fuel I have at any given point without guess work and Hobbs times. 

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Posted

When I first bought it, it wasn't painted over and I couldn't see any fuel level. I had figured that's what that cutout was for and then because nothing was visible I figured it was like my Kitfox wings and had the butt rib that he glassed over. Now knowing that's not the case. Originally I was going to have the "spuddering engine type fuel indicator" but figured while I'm working on it I may as well keep going. 

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Posted (edited)

I don't know how it might be set up to work with your wing tank, but on my Kitfox 2 which had a plastic nose tank there was a car-type license plate light mounted outside of the tank so that it lit up the tank from the side and you could see the level of fuel better thru the slot in the IP.  I am thinking about mounting small LED lights on the outside of the fuselage rib to light up my sight gauges which will have one of Bear Perkins' little red pellets floating on top of the gas inside the tubes.  EDMO

Edited by EDMO

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Posted

Maybe you can sand off the paint in the area where you can see through my fuel tank, and be able to see the fuel level there.  I think that section of the tank was more transparent then the rest of the end of the tank..  Just don't sand to far.  ;-)    JImChuk

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Posted

Maybe you can sand off the paint in the area where you can see through my fuel tank, and be able to see the fuel level there.  I think that section of the tank was more transparent then the rest of the end of the tank..  Just don't sand to far.  ;-)    JImChuk

I would try a little laquer thinner or something rather than sanding - but if you sand, use progressively finer grit and polish the marks out until you can see thru the tank - like renewing plexiglass on your windsheild or car headlights covers.   EDMO

I don't know how it might be set up to work with your wing tank, but on my Kitfox 2 which had a plastic nose tank there was a car-type license plate light mounted outside of the tank so that it lit up the tank from the side and you could see the level of fuel better thru the slot in the IP.  I am thinking about mounting small LED lights on the outside of the fuselage rib to light up my sight gauges which will have one of Bear Perkins' little red pellets floating on top of the gas inside the tubes.  EDMO

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Posted

I'll be headed out of town to go check out a Murphy Rebel but when I am back I will attempt the sanding/polishing idea. 

Looking closer it looks like I won't have any room with how the butt rib on the fuse mates up to the side of the tank. I wouldn't be able to see anything less than half way down to the bottom of the tank.

in another thread I am talking about my CQ issues with it being on the forward side of the spectrum. So another idea I am pondering as suggested by I think EDMO (apologize if I'm wrong) but to move my header tank and pump back. But if I did that I was thinking of using this fuel cell I have that's 2.5 gallons with a sending unit on it. That way I can pre calculate my fuel but on the cautionary side as soon as I'm left with just what's left in the 2.5 gallon header tank then the sender somehow lights up a dash light? Thoughts on this? It would only be an emergency notification if for any reason I am wrong or have used more fuel than planned? Also this would completely correct my CG and put me in the -15" range rather than -12 to -13".

IMG_5632.PNG

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Posted

Nice looking fuel cell - who sells it and how much is it?  EDMO

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Posted

I picked it up on eBay some time ago for a trike project. It's 2.5 gallon and they have 1 gallon also both coated or polished. I believe mine weighs just under 3lbs. 

http://m.ebay.com/itm?itemId=201370338689&fromWatch=true

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Posted (edited)

Very nice.  I paid a lot more for my 1 gallon plastic tank from Kitfox and no sender included.    EDMO

Edited by EDMO

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Posted

you could  sand it down and build two spots up with Fiber glass, drill and tap two holes for a sight tube that would be the easiest,

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Posted

The negative thing I see about the 2 1/2 gallon fuel cell is this.  You will never use the fuel in it most likely, so you are carrying around 15 lbs of weight.   (would you ever take off with the low fuel light showing?)  Adding just a few lbs of weight on the tail will move the CG back, you would have to figure out how much you need though.  The idea of a low fuel warning light is a good idea though.  Wish I had one several times.  Some have rigged them up in the top of the Avid header tank. I'm sure it's been discussed here in the past.  Not sure where it is though.  Thanks for the post, maybe I will get around to doing the low fuel light because of it.  JImChuk

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Posted (edited)

Looking over the sight tube idea, I don't think it will work out. I mean it would, but not how i'd like it. I would only be able to install the tube in such a way where I can only see half of the tank. Theres no way of accessing the tank halfway (horizontally) and down because of the butt rib and fuselage. Picture attached in next post. 

With regards to the weight in the tail - currently it weighs 61.2lbs. Ive temporarily modified the battery tray and moved it back as much as I could (8") and only gained 1.5lbs. According to the weight on the mains, my tail needs to be between 72lbs to get into the low -15's for CG. So I was thinking just as 1avidflyer suggested, of adding more lead directly at the tail. So I ordered some lead to melt down into rounded plates about 2.5" in dia. and bolting to both sides of the thru tube at the back. I've tried adding these 7.5lbs of plates (picture attached in next post) and gained 7.2lbs making the tail now a total of 68.4lbs. Note, these plates in the pic are just testing weight amounts. NOT a permanent solution. But I still need another 5lbs roughly and adding these clunky useless weights would keep me from sleeping. But, it is a quick an easy way of gaining tail weight that I'll keep in mind should the tank still not be enough.

So I figured that if I am to have a total of 5 gallons of fuel at minimum, and 15 gallons at max useful load I would prefer to shift 15+lbs of that weight that is already required to be there towards the tail. 

I like the idea of the fuel indicator also and feel that its a nice backup to have if my burn rate was to be higher than anticipated. But will have to see. 

Thanks again for all the help and suggestions guys.

Edited by fusionfab

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Posted

IMG_5633.JPG

IMG_5634.JPG

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Posted

I was once told that for every pound you add you lose 6fpm climb. Something to think about while bolting lead to your plane.

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Posted

I was once told that for every pound you add you lose 6fpm climb. Something to think about while bolting lead to your plane.

That is one of the many reasons why I despise adding lead to the tail and am in search of anything at all in order to avoid it. I have some days off coming up that I plan on using to install this fuel cell and pumps farther back. If it works to how I think it will that'll be all I need to do to gain better CQ numbers. 

My thoughts are that I won't be adding any weight to the plane this way (other than the added 1.75 lbs for larger tank, and bracket to mount it), all I'll be doing is shifting weight thats already over the mains. Additionally should for any reason my wing tanks get used up I'll still be within CG limits, lastly should I completely run out of fuel, I'll still be within limits. Fingers crossed my vision pans out.  

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Posted

I was able to see my wing tank fuel levels quite easy, and I have the same amount of stuff as you.  I would maybe tie the pitot tube to the side of the steel tube, rather than the bottom though.   I went looking for some pictures, and found this utube video showing the tank about 10-12 seconds in.  You could see the level down to 4 gallons real easy.  https://www.youtube.com/watch?v=D3dxYaxQHDY  In the second video, you can see the other side of the plane at 40-45 second mark.  JImChuk

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Posted

I doubt that any of my 4 Avids flew at a CG of 15" or more.  Usually probably around 13".   None had a heavy engine in front, but they all flew fine.  Maybe you're trying fix a problem that doesn't really exist.  Have you flown the plane at a more forward CG and don't like it?  :-)   JImChuk

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