Any one have a manual fuel measuring stick For 21.5 and 15 gal M7 tanks?

Cash,

I bought the generic fuel stick from Sporty's and the calibrated it to the best of my abilities. I have a M7-235C with 21.5 usable mains and 15.0 usable auxs. I think that is configuration C. Whacha need?

Tim

Hey drak 130 I would sure be interested in measurements up from bottom of stick corresponding to gallons for a ball park measurement to compare with gages. I normally leave 3 or 4 gallons in aux tanks for reserve but would still be good to stick mains especially when your only doing short flights and it’s been awhile since topped. Thanks. Les

Les,

Will do. Will probably head out to hanger later this week. Will send what i have. I think we both have taildraggers so that will affect accuracy of the stick vs gauges. (When I put in the CGR-30s we jacked the tail to put it in a flying attitude and then calibrated. With the stick I left it in a 3 point. Aux tanks will be more accurate as they were empty when I started the process. Mains had some fuel in them to start.

Cheers
Tim

I would strongly advise you to calibrate your own stick for YOUR airplane. Every one of these is a hand-built individual, and your tank might not be the exact same shape or volume as someone else’s. The level that equals five gallons on their stick might not be five gallons on yours, even if they are the same year and model, and same part number tank. Also, tire size will effect apparent level directly under the fuel filler neck, for the same volume of fuel.

Other variables are the length of your gear, size of your main tires, and size of the tailwheel. You need to customize for your airplane. That also goes for the oil level. Last oil change the dip stick indicated 5 qts. I measured what I drained out and it came to over 6 qts.

Thanks Andy and Montana, all I was after was a BALL PARK measurement to support or question gages. After lots of hours in over fifty year’s piloting these thing’s around the US and Canada I have become quite conservative. I like the Maule’s fuel system where I always leave 3or 4 gallons in aux tanks for reserve.

Hopefully you’ve seen the posts about making sure you can’t drop the stick into the tank.

I'll echo what Andy said about the tanks varying dramatically on their actual capacity. I know you said you were just looking to "ballpark" it but you might have a tee-ball field measurer for a major league tank or vice versus.
Case in point, I replaced the tanks in my M-5 from the old style pillow tanks to the newer style square tanks. So it should have been 20.5 usable upgrading 21.5 usable, but on floats I intentionally ran each new tank to the point of fuel exhaustion to find out the no kidding amounts usable and found one held 24.8 usable and the other 24.2 usable. So like the man said YMMV, I would definitely make my own stick and have a flange/cap on it so it can't take a swim.....


James

I did a drain and refuel on my M5 to calibrate my fuel stick. I used the tank sump drain to make sure both main tanks were bone dry. They both held 22.5 gallons. I find that the bottom of the tanks are not flat, so I have to make sure I hold the stick at the same angle for an accurate gauge.

The tank bottoms have raised “ribs” that go fore and aft (really just a fold in the metal of the tank bottom). One is more or less right under the fill. So you have to decide if you’re going to measure from the top of the rib, or angle to the side to measure from the actual tank bottom. If you use someone else’s dip stick, this is one potential variable in getting a different reading: where exactly they place the stick when measuring.

Cut a half inch dowel about 18" long then use the sump drain to completely empty the fuel tank. Make sure the plane is sitting on a level surface then measure and add 5 gallons, put the stick in the tank and use a magic marker to circle the level of the fuel. Repeat for 10, 15, and 20 gallons and you have a highly accurate means of measuring the amount of fuel in the tank...as long as the plane is on a level surface and no change is made to tires or gear.

I’m fairly ignorant when it comes to wood, but I’m pretty sure I’ve experienced problems getting an accurate dip with wood, due to the fuel wicking up the stick. Does it matter what kind of wood you use? Hardwood vs, softwood? I use a plastic tube instead. I’m too cheap to buy the pre-made ones, so I bought a few feet of hard plastic tube at the hardware store, and cut it to the correct length. I dip it in, press my finger over the top, then pull it out to read the level. I calibrated it per 9JH’s method.

Excellent point. I used a cheap softwood dowel. If I left it in the tank it would wick upwards, but when I check the tanks it’s a momentary dip followed by an immediate read. After that it seems that the fuel evaporates at the same rate it wicks. By the time I get to the other tank it’s dry and ready for use again.

M5 235C, standard legs and 8.50 tires. I developed my own chart using a generic fuel stick from Sporties. When setting level, tail down it took 6 gallons to even show at the top of the rib in the tank. It is not a linier progression above 16 gallons. It takes 21 gallons to the top of the filler neck.
When I lifted the tail to level flight attitude, I drained 24+ galons out the belly draines. Put 24 gallons back in the tanks at level flight attitude.
I just plan on 20 galons each side and hope I do not get into the bottom of the tanks.
It takes some time but it is worth it to develop your own gauge for your own aircraft.