---------------------------------------------------------- RV9-List Digest Archive --- Total Messages Posted Tue 10/05/04: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 01:09 PM - Re: Fuel valve (Chuck Jensen) 2. 01:46 PM - Re: Fuel valve (Stein Bruch) 3. 01:48 PM - Re: Nosewheel shimmy (Chuck Jensen) 4. 03:03 PM - Re: Fuel valve (cgalley) ________________________________ Message 1 _____________________________________ Time: 01:09:59 PM PST US From: Chuck Jensen Subject: RE: RV9-List: Fuel valve --> RV9-List message posted by: Chuck Jensen Cy, You wrote this this a few weeks ago. I was interested in the fuel starvation issue with low wing and fuel flow from 'both' issue. Would you, or someone be so kind as to expound on what must be shared wisdom given your brief reference. Chuck -----Original Message----- From: owner-rv9-list-server@matronics.com [mailto:owner-rv9-list-server@matronics.com]On Behalf Of cgalley Subject: Re: RV9-List: Fuel valve --> RV9-List message posted by: "cgalley" With a low winged plane you DON'T want a both. Causes fuel starvation problems. Cy Galley Safety Programs Editor Always looking for ideas and articles for EAA Sport Pilot ----- Original Message ----- From: "Konrad Werner" Subject: Re: RV9-List: Fuel valve > --> RV9-List message posted by: "Konrad Werner" > > Dear Steve, > The current valve has 3 Fuel Ports plus OFF. One of the fuel ports (your choice) is not used with the standard 2-Tank setup. > There is no "Both" on this valve. > do not archive > ----- Original Message ----- > From: Steve Sampson > To: rv9-list@matronics.com > Sent: Monday, August 23, 2004 12:39 PM > Subject: RV9-List: Fuel valve > > > --> RV9-List message posted by: "Steve Sampson" > > Could someone remind me about the positions on the VANS supplied valve. > One position is L Tank, one R Tank. Am I correct in thinking the other two > are both 'OFF' or is one 'Both'? I am just getting some labelling made up > and cant get to the valve. > > Thanks, Steve. > > #90360 > UK > > --- > > ________________________________ Message 2 _____________________________________ Time: 01:46:45 PM PST US From: "Stein Bruch" Subject: RE: RV9-List: Fuel valve --> RV9-List message posted by: "Stein Bruch" Usually with a low wing airplane a "Both" selection is a "no-no" There are a couple of reasons #1) reason is that because of the venting/pressurization issues with the tanks, you can and will most likely end up with one tank being pressurized more than the other tank. This is a reality with our homebuilt airplanes, the difference in venting pressure only has to be in fractions and then here you go: With a seletor in "both", the tank with the higher pressure in it (because remembering that both aren't 100% equal) begins to feed fuel to the lower pressure tank. This tank then will dump the fuel out of the vent and this whole process will go on until one or both tanks are completely empty. Even some high wing airplanes with a fuel system that doesn't have a "common" or "interconnected" vent line can suffer from the same problems. #2) The next problem is gravity. Assuming you can get the vent pressures on the tanks to be 100% equal (by running a common tie between the vent lines or something), you still have to worry about gravity. Gravity will always move the fuel to the lowest tank, and if you are using a "both" valve while the fule drains to the lowest tank, the system will then start drawing air from the other tank. Bad Deal all the way around. I've seen some people try to "roll their own" BOTH selection by usine two boost pumps and elaborate check valves, but in the end it's just easier to switch tanks every once and awhile. Fuel systems are not something to take lightly, and I would strongly discourage anyone from taking on modification of these systems lightly!! One could write pages on the differences in design of fuel systems between high and low wing planes, but that's the short version of it! Cheers, Stein Bruch RV6's, Minneapolis -----Original Message----- From: owner-rv9-list-server@matronics.com [mailto:owner-rv9-list-server@matronics.com]On Behalf Of Chuck Jensen Subject: RE: RV9-List: Fuel valve --> RV9-List message posted by: Chuck Jensen Cy, You wrote this this a few weeks ago. I was interested in the fuel starvation issue with low wing and fuel flow from 'both' issue. Would you, or someone be so kind as to expound on what must be shared wisdom given your brief reference. Chuck -----Original Message----- From: owner-rv9-list-server@matronics.com [mailto:owner-rv9-list-server@matronics.com]On Behalf Of cgalley Subject: Re: RV9-List: Fuel valve --> RV9-List message posted by: "cgalley" With a low winged plane you DON'T want a both. Causes fuel starvation problems. Cy Galley Safety Programs Editor Always looking for ideas and articles for EAA Sport Pilot ----- Original Message ----- From: "Konrad Werner" Subject: Re: RV9-List: Fuel valve > --> RV9-List message posted by: "Konrad Werner" > > Dear Steve, > The current valve has 3 Fuel Ports plus OFF. One of the fuel ports (your choice) is not used with the standard 2-Tank setup. > There is no "Both" on this valve. > do not archive > ----- Original Message ----- > From: Steve Sampson > To: rv9-list@matronics.com > Sent: Monday, August 23, 2004 12:39 PM > Subject: RV9-List: Fuel valve > > > --> RV9-List message posted by: "Steve Sampson" > > Could someone remind me about the positions on the VANS supplied valve. > One position is L Tank, one R Tank. Am I correct in thinking the other two > are both 'OFF' or is one 'Both'? I am just getting some labelling made up > and cant get to the valve. > > Thanks, Steve. > > #90360 > UK > > --- > > ________________________________ Message 3 _____________________________________ Time: 01:48:08 PM PST US From: Chuck Jensen Subject: RE: RV9-List: Nosewheel shimmy --> RV9-List message posted by: Chuck Jensen I don't know much about RVs (well, make that nothing, actually) but Velocity aircraft have had some of the same issue about nose wheel shimmy...with equal resolution--marginal. However, you're issue about the shimmy associated with braking may be a somewhat different and may be related to harmonic vibrations through the gear legs that are caused by braking action. The harmonic vibration can be easily mistaken for shimmy in the nose wheel. Just an alternative thought. Chuck -----Original Message----- From: owner-rv9-list-server@matronics.com [mailto:owner-rv9-list-server@matronics.com]On Behalf Of Dale Larsen Subject: Re: RV9-List: Nosewheel shimmy --> RV9-List message posted by: "Dale Larsen" Axle bolt tension is good, breakout tension is adjusted per plans with a fish scale. Tire pressure is good, and wheel rotates freely. On closer investigation, it only occurs at the end of the rollout, when you start to brake hard. If you don't brake at all, it dosent shimmy. I would think that if it were due to a balance condition that it would be poportional to the speed of the wheel. No shimmy on takeoff. > --> RV9-List message posted by: "fcs@jlc.net" > > > > It moves 1 to 1-1/2 inches at about a 3 Hz rate. > > Maybe the wheel is out of balance? > > Dale > > Wow, and you say you can't feel this?!? I suppose it is possible that > your tube is folded or pinched inside the tire, causing major imbalance. > If you think this is the case, you should immediately take the wheel apart > and check. Trust me, you don't want to experience a flat tire. Some > degree of bouncing is to be expected with a spring type nose gear leg, but > that's way more than I have seen. Check your axle bolt tension while > you're at it and make sure your wheel is rotating freely. Also check your > nose fork breakout tension. If it is too loose the wheel can wobble > violently from side to side just as it touches the pavement. Use a > fish-scale to actually set it per Vans instructions. The fork must have a > good bit of tension and not just swivel freely. If you can't find the > culprit, I would give Vans a call and see if they have any further clues. > > ________________________________ Message 4 _____________________________________ Time: 03:03:59 PM PST US From: "cgalley" Subject: Re: RV9-List: Fuel valve --> RV9-List message posted by: "cgalley" Take two straws and put them in your mouth. Place one of the straws in a can of pop and suck. How much pop did you get? I'll bet none because air is easier to suck than pop. Close off the straw that isn't in the pop and voila, you can suck the pop. If you use a both tank position, then when one tank empties, no matter how much gas is in the other tank, you will suck air and the engine will quit. Cy Galley EAA Safety Programs Editor Always looking for ideas and articles for EAA Sport Pilot ----- Original Message ----- From: "Chuck Jensen" Subject: RE: RV9-List: Fuel valve > --> RV9-List message posted by: Chuck Jensen > > Cy, > > You wrote this this a few weeks ago. I was interested in the fuel > starvation issue with low wing and fuel flow from 'both' issue. Would you, > or someone be so kind as to expound on what must be shared wisdom given your > brief reference. > > Chuck > > -----Original Message----- > From: owner-rv9-list-server@matronics.com > [mailto:owner-rv9-list-server@matronics.com]On Behalf Of cgalley > To: rv9-list@matronics.com > Subject: Re: RV9-List: Fuel valve > > > --> RV9-List message posted by: "cgalley" > > With a low winged plane you DON'T want a both. Causes fuel starvation > problems. > > Cy Galley > Safety Programs Editor > Always looking for ideas and articles for EAA Sport Pilot > > ----- Original Message ----- > From: "Konrad Werner" > To: > Subject: Re: RV9-List: Fuel valve > > > > --> RV9-List message posted by: "Konrad Werner" > > > > Dear Steve, > > The current valve has 3 Fuel Ports plus OFF. One of the fuel ports (your > choice) is not used with the standard 2-Tank setup. > > There is no "Both" on this valve. > > do not archive > > ----- Original Message ----- > > From: Steve Sampson > > To: rv9-list@matronics.com > > Sent: Monday, August 23, 2004 12:39 PM > > Subject: RV9-List: Fuel valve > > > > > > --> RV9-List message posted by: "Steve Sampson" > > > > > Could someone remind me about the positions on the VANS supplied valve. > > One position is L Tank, one R Tank. Am I correct in thinking the other > two > > are both 'OFF' or is one 'Both'? I am just getting some labelling made > up > > and cant get to the valve. > > > > Thanks, Steve. > > > > #90360 > > UK > > > > --- > > > > > >