REFLECTOR: FUEL FEED [heur]

Wed Feb 16 11:21:21 CST 2005

If the tanks are vented to the upper part of the engine compartment ... I think there is little chance it can ignite unless fuel actually leaked out.  Right, Wrong?  I may have to put a lead on it (to top or bottom?)

	-----Original Message----- 
	From: Jim Sower [mailto:canarder at frontiernet.net] 
	Sent: Tue 2/15/2005 11:03 PM 
	To: Velocity Aircraft Owners and Builders list 
	Cc: 
	Subject: Re: REFLECTOR: FUEL FEED [heur]

	Ron Brown wrote:

		Tom, 

		I don't think it is a good idea to vent the fuel system into the engine compartment, especially if you happen to flip upside down during a crash landing.  You will have lots of fuel draining out the vent system into the hot engine compartment. 

	Agreed.  I ended up with a sump vent to the top of the firewall that I can cap off when sump is full.

		With the factory designed fuel vent line routed up to the top of the firewall then back down to exit the bottom of the fuselage, fuel will not leak out of the vent system when the airplane is upside down. 

	I think pretty much all canard vents are like that now.

		One other thought on uneven fuel flow, even if the vents are tied together and the plane is flying level/ball centered: there is a possibility that an air bubble trapped in the vent line with fuel on either side of the bubble can cause an uneven venting of the tanks.  This wouldn't happen if the vent lines always slope upward to the manifold.  I think this may be the scenario that Jim Sower is seeing from time to time.  

	Nope.  That's the very first thing I fixed.  Actually, the builder had wiped out his LG and had the Velocity factory fix it, and they left one vent to the top of the right strake like it should be, and plumbed the other through the fuselage side into the BOTTOM of the left strake and thence up to the top of the left tank.  There was a permanent 7" column of fuel in that loop.  It's the SECOND thing I fixed (after ensuring that all the vent lines ran uphill to the top of the firewall).

		I have had it happen a couple of times on long trips after filling the tanks nearly full.  After landing and parking in my hanger, the fuel tanks were 5 or so gallons different and remained that way until I opened the fuel caps.  STRANGE!  Wings are level when parked in the hanger.  Another experiment - I placed a 2 x 6 under one main tire, simulating a wings down.  Guess what - the fuel level difference was MUCH LESS than I have seen in the air. 

	I did that too.  Full tanks will indicate full pretty much no matter what.  Jack up one wing and the indications will shift immediately (high strake will have fuel piled up near fuselage where the sender is and will indicate more fuel than is there; low strake will have fuel piled up outboard and lower level next to fuselage where sender is.  Eventually tanks may "even out".  But then again, they may not.

		But again, it could be fuel caps that are not always sealing perfectly for every flight. 

	But if you seal the caps with Al faced tape so there's no possibility that they're leaking, and one tank STILL doesn't transfer,  then what?

		Ronnie 

		----- Original Message ----- From: "Tom Martino" <tmartino at troubleshooter.com> <mailto:tmartino at troubleshooter.com>  
		To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org> <mailto:reflector at tvbf.org>  
		Sent: Tuesday, February 15, 2005 12:23 PM 
		Subject: RE: REFLECTOR: FUEL FEED [heur] 

		My plane flies perfectly.  Not my opinion, it is the assessment of my 
		test pilot.  The ball is in the center and the plane flies "hands off" 
		straight and level. 

		I will keep looking. 

		-----Original Message----- 
		From: Scott Derrick [mailto:scott at tnstaafl.net] 
		Sent: Tuesday, February 15, 2005 9:18 AM 
		To: Velocity Aircraft Owners and Builders list 
		Subject: Re: REFLECTOR: FUEL FEED [heur] 

		A leaking gas cap can cause uneven fuel flow but is not the prime 
		culprit. A bit of fuel valve lube applied to the O ring once a year will 

		insure this doesn't happen. 

		A miss-rigged airplane is most likely the cause. Shim your rudders so 
		the ball is right in the middle and you will get perfect fuel flow. 

		To test, be sure your turn and bank is installed correctly first, 
		garbage in garbage out. Then fly, this is the fun part.. Once you see an 

		uneven condition, press on the rudder that will put the ball in the 
		middle. If you want to even up the tanks fast, press on the correct 
		rudder so the ball is on the other side for a couple minutes, you'll see 

		the fuel even up and even go into the opposite imbalance if you keep the 

		rudder depressed. Then hold the rudder so the ball is centered, fuel 
		will flow as it was designed to. 

		Scott 

		Tom Martino wrote: 

			Well, now that I'm in my test flying mode ... I will really be asking 
			a lot of questions. 

			Here are some of them, as they relate to my fuel system: 

			1. What makes the fuel tanks feed unevenly to the header tank/engine? 
			(My right tank is feeding twice as fast as my right tank.) 

			2. Will that cause a problem when the fast-feeding tank runs out? 

			3. I used the larger vent lines for my tanks and tied them al together 

			with a manifold, then vented the entire system out through the top of 
			my firewall in the engine compartment (about four inches below my naca 

			duct). Do you think the system gets enough venting there? 

			4. Is there a need for a "whistle" hole in any of the tank vents ... 
			for additional venting (like we do with the crankcase breather? 

			Any help is appreciated from my more experienced Velocitologists J 

			Tom 

			N173EX 

			(A mere 6 hours) 

			----------------------------------------------------------------------- 

		- 

			_______________________________________________ 
			To change your email address, visit 

		http://www.tvbf.org/mailman/listinfo/reflector 

			Visit the gallery!  www.tvbf.org/gallery 
			user:pw = tvbf:jamaicangoose 
			Check new archives: www.tvbf.org/pipermail 
			Check old archives: http://www.tvbf.org/archives/velocity/maillist.html 

		_______________________________________________ 
		To change your email address, visit 
		http://www.tvbf.org/mailman/listinfo/reflector 

		Visit the gallery!  www.tvbf.org/gallery 
		user:pw = tvbf:jamaicangoose 
		Check new archives: www.tvbf.org/pipermail 
		Check old archives: http://www.tvbf.org/archives/velocity/maillist.html 

		_______________________________________________ 
		To change your email address, visit http://www.tvbf.org/mailman/listinfo/reflector 

		Visit the gallery!  www.tvbf.org/gallery 
		user:pw =vbf:jamaicangoose 
		Check new archives: www.tvbf.org/pipermail 
		Check old archives: http://www.tvbf.org/archives/velocity/maillist.html 

		_______________________________________________ 
		To change your email address, visit http://www.tvbf.org/mailman/listinfo/reflector 

		Visit the gallery!  www.tvbf.org/gallery 
		user:pw = tvbf:jamaicangoose 
		Check new archives: www.tvbf.org/pipermail 
		Check old archives: http://www.tvbf.org/archives/velocity/maillist.html 

-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/ms-tnef
Size: 10174 bytes
Desc: not available
Url : http://www.tvbf.org/mailman/private/reflector/attachments/20050216/ab0b4159/attachment-0001.bin