Roger Lee Posted June 20, 2010 Report Share Posted June 20, 2010 Posted by Trevorvilla from another site: LocationUK Uneven fuel usage from tanks I have a strange problem, I have read about this issue with tanks and reading them. My CT seems to use the left tank to the point I cant see anything in the sight tube then the right tank starts to be used. This seems to be a common thing here in the UK, a lot of other owners have said the same thing. It is definitely not flying one wing low, even after flight and in a perfectly level hangar with the wings level, the fuel doesn't balance out! Seems very strange to me! I have drained the fuel off on more than one occasion to see if the fuel does come out off the right tank when the left is empty, which it appears to each time. any thoughts on this, it seems to be defying gravity! I did notice that someone mentioned fuel tank filters somewhere on this forum, this is something I am not aware of in the UK version (or could this be the issue?) Trevor Link to comment Share on other sites More sharing options...
Roger Lee Posted June 20, 2010 Author Report Share Posted June 20, 2010 Hi Trevor, The CT has the same fuel tanks in the UK as they do in the US or Australia. This was a subject discussed a few years back, but now it is new news because we have new fliers. The reason for the uneven flow is the tank design. They are very flat and if you fly out of coordination even a little one will drain a little faster. The more out of trim the faster the uneven drain. The slip indicators whether manual or Dynon are not always as accurate as they seem. A person put them in so a little human error can and is the cause. Try this, take a piece of yarn 9-10 inches long. Tape it to the front of your plane right above the center cowl screw. Then fly and see if your ball is dead center. Good Luck. Knowing that your left wing drains faster than your right, so does mine, fly with the ball to the left about 1/2 - 3/4 ball. I'll bet your fuel drain will be even. Remember that the fuel will follow the ball. If the ball is out to the left the fuel will go there and if the ball is out to the right it will go to the right. The fuel line circuit between tanks is open all the time. The fuel shut off only stops fuel going to the engine. This basic explanation used to be posted on the FD website, but has been replaced. Even though you may think your wings are perfectly flat while flying they may in fact be off just enough and if you are having the uneven drain then that is true. Link to comment Share on other sites More sharing options...
N78BZ Posted June 21, 2010 Report Share Posted June 21, 2010 I have found that when flying level, on autopilot, with the ball centered, my CTLS seems to drain the left tank first, too. To manage that, I simply set my 696 to give me a reminder to "switch fuel tanks" every 30 minutes. When that reminder pops us, I adjust the rudder trim to move the ball slightly to the "other" side. When on autopilot, that lifts the fuller wing slightly and helps to equalized the tanks. This lets me actively keep the tanks relatively equal on long flights. Link to comment Share on other sites More sharing options...
John Stamper Posted June 21, 2010 Report Share Posted June 21, 2010 Hi Roger, I'm fairly new to the CTSW and would welcome an explanation on the following if you can help. There are a couple of things regarding the fuel tanks I don't understand. Why do US CTSW's have two dipsticks but the UK ones only have one? Why are the fuel caps different distances from the aircraft centreline? Our UK CTSW dipstick is calibrated in litres. But it doesn't match another CTSW's dipstick also calibrated in litres. So do you think one of the dipstick is wrong, or could there have been a change in fuel tank shape during the production run? John. Link to comment Share on other sites More sharing options...
chanik Posted June 21, 2010 Report Share Posted June 21, 2010 Having fiddled with this quite a bit myself, I think it is worth noting that while the fuel follows the ball, at first, this makes the tanks look MORE uneven. When you skid a bit to bring the emptier wing down, the immediate effect is to slosh that fuel outboard while the fuller tank sloshes inward so while you are trying to even them up, it looks like the lower tank is even emptier while the other one looks fuller. Once you stop skidding, you see the fuel has tranferred. Link to comment Share on other sites More sharing options...
Roger Lee Posted June 21, 2010 Author Report Share Posted June 21, 2010 Hi John, I'm not sure what you exactly mean by 2 dipsticks? We in the US have one dip stick and it is marked on each side. One side is 1/2 gal. different than the other. Whether you live in the US or any where else with a CT the dip stick was meant as a reasonable fuel level check and may not be super accurate. The dip stick is to get you close with the fuel level so you can make an educated decision on whether you have enough fuel. It is very close, but there are things that can affect that reading. Such as are you leaning on the wing and causing the level to tilt to the out board, is the plane level to start with, is the fuel moving at all when you dip it. Any of these in the slightest may affect the fuel reading on the stick by .5-1.5 gal. I always tell people don't ever try to cut fuel close, just keep the level up and then don't worry or don't try to go too far without a refuel. Safety first. The cap issue you mention I have never measured. I don't know how big a difference it would make. Just think of dip sticks as very close estimators. This may be why one stick may be slightly different from batch to batch, but I'm not 100% sure. I hoped this helped. Link to comment Share on other sites More sharing options...
John Stamper Posted June 22, 2010 Report Share Posted June 22, 2010 Hi Roger, Thanks for explaining your US dipsticks. From another site I'd seen photos of the left and right markings on your US dipsticks. So you use a different set of markings for each tank. On UK CTSW's our dipstick is only marked on one side so we use the same scale for each tank. I just wondered why that was. But as you say its probably not that important. Regards John. Link to comment Share on other sites More sharing options...
Roger Lee Posted June 22, 2010 Author Report Share Posted June 22, 2010 Hi John Stamper, For the little ours is off we could get away with just one side. Link to comment Share on other sites More sharing options...
John Stamper Posted July 29, 2010 Report Share Posted July 29, 2010 Hi Roger, I lost our CTSW dipstick last week. Left it on the wing. Also lost a fuel cap, but it was found a few minutes after I departed! So I ordered a replacement and got a nice matt black one. Today I was handed back the original dipstick which had been found on the numbers at the start of the runway. I've attached a photo showing both dipsticks so you can see the differences. They are calibrated in litres. I've rubbed chalk on the matt black one to highlight the markings. Regards John. Link to comment Share on other sites More sharing options...
Roger Lee Posted July 30, 2010 Author Report Share Posted July 30, 2010 Hi John, That's a pretty fair difference. It would be interesting to hear what FD would have to say because I'm at a loss for words. Which one do you think is more accurate? I know I left myself wide open with that comment. Link to comment Share on other sites More sharing options...
airhound Posted July 30, 2010 Report Share Posted July 30, 2010 Whats 5 liters amongst friends? By the way, what is 5 liters? Link to comment Share on other sites More sharing options...
Roger Lee Posted July 30, 2010 Author Report Share Posted July 30, 2010 5 liters is about 1.3 gals. Link to comment Share on other sites More sharing options...
John Stamper Posted July 30, 2010 Report Share Posted July 30, 2010 Hi Roger, The main differences between the dipsticks are the 5 litre (1.3 usg) mark and marks above 40 litre (10.5 usg). I try to stay away from the lower level for safety reasons! As our microlight CTSW is only allowed to gross at 450kg (992 lbs) I don't fill to the higher level either! So, as there's not much difference between the dipsticks at the levels I'll use, the differences are a bit academic. But I'd still be interested in an explanation for the differences. Oliver, our UK distributor, was at my local airport today so I showed him the photo and the black dipstick. He grabbed his own CTLS dipstick and saw the difference first hand but he couldn't explain it. A mystery. Regards John. Link to comment Share on other sites More sharing options...
Runtoeat Posted August 2, 2010 Report Share Posted August 2, 2010 This topic was discussed on another forum a while ago and I noted at the time that my dipstick has two calibrations, one side of the dipstick is for the left fuel tank and the other side is for the right fuel tank. Here's the photos of my dipstick. You see that there is a 3/8" difference between 17 gal. marks. I think we need to get a reply from FD that addresses the differences. This is probably more important for our European friends since they seem to run with lower fuel levels to keep weight down. Personally, I fly with full tanks whenever I can. If one flies with low fuel levels, they might run into a fuel starvation due to the uneven drain of our tanks. Link to comment Share on other sites More sharing options...
Roger Lee Posted August 2, 2010 Author Report Share Posted August 2, 2010 Hi Dick, It's the same on all of them. It may just be the way the tanks rae mounted in the wings? Either way that little bit should never make a difference as you should never get to a point in a flight that that 3/8" worth of fuel level should matter. If I am staying around my area as most of us do I never put more than 15 in each wing. That will help prevent any venting on the wing. If I fly a long cross country I never put more than 16.5 in each wing. You most likely will never fly for that length of time and I will fill up after 4 hours of flight anyway just in case I have to divert. For me I never worry about fuel because I always have plenty and the only time there is too much fuel on board is.......when I'm on fire. Some dip sticks have gallons on one side and liters on the other. They don't even bother with left or right. It just isn't a real problem for us. The dip stick is an extremely close approximation, just like the site tubes because different factors may cause you a slight misread so never allowing a low fuel situation will always serve you well. Link to comment Share on other sites More sharing options...
Runtoeat Posted August 2, 2010 Report Share Posted August 2, 2010 Hi Roger. I agree that the 3/8" isn't that big of a deal but the topic keeps coming up and it would be nice to get a comment from FD. I keep about 14 to 15 gallons in each tank usually also. The only time I've "topped" off the tanks to a full 33 gallons was this week. I just got back from Oshkosh. My first time there. What an amazing collection of people and planes. We flew my friend's CTLS from my home base at Willow Run airport in Ypsilanti, Michigan (home of B-24 bomber production for WWII) around the south side of Chicago and up to Wittman airport. Going back, we flew at "classified" altitude over Lake Michigan. The CTLS showed it's tremendous capability for cross country travel. We traveled 610 miles round trip and averaged 5.2 gal/hr. fuel burn. I still can't believe how fast we came back from KOSH to KYIP without any help from a tailwind. About 2:10 for 250 miles which included our climb up to altitude at full throttle for about 20 minutes. This would have been about a 10 hour car ride which includes the unwanted ride around Chicago. The CTLS was comfortable and efficient. What a great way to travel! Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.