---------------------------------------------------------- Zenith-List Digest Archive --- Total Messages Posted Sun 02/15/04: 14 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:16 AM - Aileron Trim & Deflection (Bob Miller) 2. 06:56 AM - 701 seat/flap (Flydog1966@aol.com) 3. 08:49 AM - Re: Aileron Trim & Deflection (bryanmmartin@comcast.net) 4. 08:57 AM - Slat Skin Support Angles - Rivet edge spacing... (Bima, Martin) 5. 09:50 AM - Re: Stratus Subaru cooling (John Karnes) 6. 12:19 PM - Re: Slat Skin Support Angles - Rivet edge spacing... (Ed Kramer) 7. 03:37 PM - Re: Stratus Subaru cooling (Leo Gates) 8. 03:57 PM - Re: Stratus Subaru cooling (John Karnes) 9. 04:00 PM - venturi troubles?? (John Karnes) 10. 05:26 PM - Re: venturi troubles?? (Ray Montagne) 11. 05:30 PM - Re: Stratus Subaru cooling (Leo Gates) 12. 05:48 PM - Re: Stratus Subaru cooling (Dave Austin) 13. 06:20 PM - Re: venturi troubles?? (Benford2@aol.com) 14. 07:28 PM - Re: Stratus Subaru cooling (Tim & Diane Shankland) ________________________________ Message 1 _____________________________________ Time: 06:16:43 AM PST US From: "Bob Miller" Subject: Zenith-List: Aileron Trim & Deflection --> Zenith-List message posted by: "Bob Miller" Time for public embarrassment. Dang!! As Bryan Martin points out, my threaded rod idea won't work as described. The ailerons would stay centered, not the stick, because the airstream is still the only force acting on the ailerons. I do understand that the deflected control surface creates drag, but there would sure be less drag if the control surface could be deflected without the additional drag of an opposing trim tab. To make my device work, springs would be required to keep the stick centered, kind of like using springs to return rudder pedals to center. I wonder how much spring pressure would be required, and how it would affect the force necessary for aileron control? In any event it's probably enough to undo the advantage of using hinged ailerons. Regarding weight in the right baggage compartment, it would require 57 pounds there to exert the same moment as a 200 # passenger. How would you calculate which would have a greater impact on performance, additional weight or aileron trim? Bob PS: If one has a header tank only, and for a given weight distribution, wouldn't aileron trim would stay the same throughout all aspects of the flight? (I'm thinking now of a ground adjustable trim tab if the spring and threaded rod idea isn't practical.) ----- Original Message ----- From: Subject: Re: Zenith-List: 601 Alternative Aileron Trim > --> Zenith-List message posted by: bryanmmartin@comcast.net > > If I'm reading your description correctly it seem you are describing a device to deflect the ailerons enough to trim the airplane while keeping the stick centered. > > First of all this adds some parts to the aileron control path and may introduce more failure modes. > > Second this device will not have the desired effect. In order to trim the airplane, you must deflect a control surface. This requires that a force be exerted on the ailerons. This force can be exerted by a trim tab or the by the control cables. Without a trim tab, the cables will still be exerting the same force on the ailerons no matter what position the stick is in. In order to conteract this trim force another force must be introduced, not just a displacement of the control system. If your device were conected to a spring and could be used to adjust the spring force on the control system, it would have the desired effect. > > Some airplanes use an adjustable spring (or bungee cord system) to apply trim forces, but this does not eliminate trim drag. The control surface is still deflected which produces an increased drag. To eliminate trim drag the only solution it to physically balance the airplane by adjusting the center of gravity (i. e. put some luggage in the wing locker on the light side). > > Bryan Martin ________________________________ Message 2 _____________________________________ Time: 06:56:15 AM PST US From: Flydog1966@aol.com Subject: Zenith-List: 701 seat/flap --> Zenith-List message posted by: Flydog1966@aol.com Zenith used to recomend 60-65 m.m. clearence between the seat bottom, and the top of the gear channel. It seems they have some concearn about the seat interfering with the flap leaver, and now recomend measuring down from the top of the seat front 115 m.m. This will put the lowest part of the seat ~85 m.m. above the floor, but only~50m.m. above the top of the gear channel. Less than the 60-65 they used to recomend. Could anyone "De-confuse"me? My dwgs are out in the garrage, but I think the channel height is 35m.m., and the seat front 200 m.m.. Thanks Phil do not archive ________________________________ Message 3 _____________________________________ Time: 08:49:17 AM PST US From: bryanmmartin@comcast.net Subject: Re: Zenith-List: Aileron Trim & Deflection --> Zenith-List message posted by: bryanmmartin@comcast.net > --> Zenith-List message posted by: "Bob Miller" > > I do understand that the deflected control surface creates drag, but there > would sure be less drag if the control surface could be deflected without > the additional drag of an opposing trim tab. The trim tab does create some small amount of additional drag but it does have one advantage, if a control cable or linkage breaks, you can use the trim tab to control the airplane to some degree. This might make it possible to make a safe landing. > To make my device work, > springs would be required to keep the stick centered, kind of like using > springs to return rudder pedals to center. You don't really want to keep the stick centered, just balance the trim forces. If the ailerons are deflected you want the stick deflected, otherwise you may not be able to use full deflection in the other direction if needed. > I wonder how much spring > pressure would be required, and how it would affect the force necessary for > aileron control? In any event it's probably enough to undo the advantage of > using hinged ailerons. Hinged ailerons will create more drag than the hingless ones unless you take care to seal the hinge line gap. And yes, springs will affect the control forces more than a trim tab. > > PS: If one has a header tank only, and for a given weight distribution, > wouldn't aileron trim would stay the same throughout all aspects of the > flight? (I'm thinking now of a ground adjustable trim tab if the spring and > threaded rod idea isn't practical.) > Yes it would. Even with wing tanks, it's possible to keep the lateral CG nearly constant by switching tanks at regular intervals. An ground adjustable trim tab should work fine. Bryan Martin Do not archive ________________________________ Message 4 _____________________________________ Time: 08:57:31 AM PST US From: "Bima, Martin" Subject: Zenith-List: Slat Skin Support Angles - Rivet edge spacing... --> Zenith-List message posted by: "Bima, Martin" Is anyone else having trouble maintaining the 2D rivet center to edge spacing for the skin support angles near the slat? I can get it but with incredible effort. Anybody have a easier method than shown in the manual? Thanks Martin Bima Winnipeg, Canada STOL-Vair 20% Slat Skin Support Angles - Rivet edge spacing... Is anyone else having trouble maintaining the 2D rivet center to edge spacing for the skin support angles near the slat? I can get it but with incredible effort. Anybody have a easier method than shown in the manual? Thanks Martin Bima Winnipeg, Canada STOL-Vair 20% ________________________________ Message 5 _____________________________________ Time: 09:50:10 AM PST US From: "John Karnes" Subject: Re: Zenith-List: Stratus Subaru cooling --> Zenith-List message posted by: "John Karnes" > Did it make any difference? Not really. Temps continued to climb toward 230 and had to abort climb out every time... > Did you do anything about the heat from the muffler and pipes and > seal the radiator real well when you moved the radiator rearward? No. I figured that the space between the two wouldn't need any heat insulation. I did seal the radiator both behind and on the sides. > Did you put anything on the outside of the radiator to assist the draw > on the backside? Someone just wrote and talked about facilitating draw of air through the rad by establishing an area of lower pressure behind the rad. I was under the belief that you wanted to force all the air past the cooling coils and wanted to block the exit in the rear... > Was your scoop designed to smooth the flow around the radiator elbows > and over the end of the radiator? No. I just constructed a flared box and riveted it onto the front of the rad. I will say, though, that the muffler I had was one I inherited and hung down in a position that I'm sure obstructed air flow. When I changed to pipes and motorcycle mufflers for each header, and moved the rad to the "chin," my temps dropped DRAMATICALLY. As I stated before, I established a service ceiling of 12,500' on thursday and was on climb out the entire time. At no time did the water temp ever reach 210 deg F. Hope this helps... John Karnes Port Orchard, WA N601JK ________________________________ Message 6 _____________________________________ Time: 12:19:12 PM PST US From: "Ed Kramer" Subject: Re: Zenith-List: Slat Skin Support Angles - Rivet edge spacing... --> Zenith-List message posted by: "Ed Kramer" Martin, If your talking about the "L" channel that gets bent to the contour of the nose ribs at the slat support. I remember having to be extra careful cutting the notch for the bend. 2-D can be maintained with some difficulty. Ed Kramer West Seneca, NY CH 701 edair701@adelphia.net Build Status: Completed: Rudder, Left wing, Right wing. Flaperons at 50% > > Is anyone else having trouble maintaining the 2D rivet center to edge > spacing for the skin support angles near the slat? > > I can get it but with incredible effort. > > Anybody have a easier method than shown in the manual? > > > Thanks > > Martin Bima > Winnipeg, Canada > STOL-Vair > 20% ________________________________ Message 7 _____________________________________ Time: 03:37:03 PM PST US From: Leo Gates Subject: Re: Zenith-List: Stratus Subaru cooling --> Zenith-List message posted by: Leo Gates John Karnes wrote: >--> Zenith-List message posted by: "John Karnes" > >>Did you put anything on the outside of the radiator to assist the draw >>on the backside? >> >> >Someone just wrote and talked about facilitating draw of air through the >rad by establishing an area of lower pressure behind the rad. I was under >the belief that you wanted to force all the air past the cooling coils and >wanted to block the exit in the rear... > OOPS! The key is to GET THE BAD AIR OUT! You can't push a string. My erudite contribution. Leo Gates ________________________________ Message 8 _____________________________________ Time: 03:57:09 PM PST US From: "John Karnes" Subject: Re: Zenith-List: Stratus Subaru cooling --> Zenith-List message posted by: "John Karnes" I was under > >the belief that you wanted to force all the air past the cooling coils and > >wanted to block the exit in the rear... > > > OOPS! The key is to GET THE BAD AIR OUT! You can't push a string. > > My erudite contribution. > > Leo Gates But isn't the "bad air" forced out the bottom of the rad past the cooling coils and fins, thus creating the cooling effect you are after??? John Karnes ________________________________ Message 9 _____________________________________ Time: 04:00:25 PM PST US From: "John Karnes" Subject: Zenith-List: venturi troubles?? --> Zenith-List message posted by: "John Karnes" When I have been flying lately, my gyro horizon has started tumbling after flying about 20-30 minutes. It is connected to a 4" venturi located on the left bottom fuse. Is it possible that the venturi is icing up and losing vacuum? OAT has been about 40 deg F. John Karnes Port Orchard, WA N601JK ________________________________ Message 10 ____________________________________ Time: 05:26:49 PM PST US Subject: Re: Zenith-List: venturi troubles?? From: Ray Montagne --> Zenith-List message posted by: Ray Montagne On 2/15/04 4:00 PM, "John Karnes" wrote: > --> Zenith-List message posted by: "John Karnes" > > When I have been flying lately, my gyro horizon has started tumbling after > flying about 20-30 minutes. It is connected to a 4" venturi located on the > left bottom fuse. Is it possible that the venturi is icing up and losing > vacuum? OAT has been about 40 deg F. > > John Karnes > Port Orchard, WA > N601JK > Absolutely possible! Remember that a Venturi is creating a low pressure area and therefore a drop in temperature. DO NOT ARCHIVE Best Regards, Ray Montagne Cupertino, CA =========================================================================== Zenith Aircraft Zodiac CH-601-XL, Jabiru 3300 Construction Log & Photos: Build Status: Rudder completed Elevator Completed Stabilizer Completed Flaps Completed Ailerons Completed Right Wing Completed Right Wing Tip Completed Left Wing Completed Right Wing Tip Completed Fuselage Under Construction NOTE: Heavy SPAM filters in place. Replies that do not include the word 'Zenith' or 'Zodiac' will be rejected and will not be viewable by me. =========================================================================== ________________________________ Message 11 ____________________________________ Time: 05:30:52 PM PST US From: Leo Gates Subject: Re: Zenith-List: Stratus Subaru cooling --> Zenith-List message posted by: Leo Gates John Karnes wrote: >--> Zenith-List message posted by: "John Karnes" > > I was under > > >>>the belief that you wanted to force all the air past the cooling coils >>> >>> >and > > >>>wanted to block the exit in the rear... >>> >>> >>> >>OOPS! The key is to GET THE BAD AIR OUT! You can't push a string. >> >>My erudite contribution. >> >>Leo Gates >> >> > >But isn't the "bad air" forced out the bottom of the rad past the cooling >coils and fins, thus creating the cooling effect you are after??? > >John Karnes > >John, > The hot air needs to be sucked out. Forcing air into rad simply compacts it, if it cant exit. The cool air will also expand further compacting the flow. Rule of thumb - Three times the area of the inlet for the outlet. Leo ________________________________ Message 12 ____________________________________ Time: 05:48:54 PM PST US From: "Dave Austin" Subject: Re: Zenith-List: Stratus Subaru cooling --> Zenith-List message posted by: "Dave Austin" Negative, John. The rad just becomes a flat plate pushing into the air. Low pressure behind is the answer. Think about Chris Heintz' answer to better cooling, which is to put a flange on the cowl at the air exit at the bottom rear. That flange creates a low pressure area to draw the hot air out of the cowl. Dave Austin 601HDS - 912 ________________________________ Message 13 ____________________________________ Time: 06:20:25 PM PST US From: Benford2@aol.com Subject: Re: Zenith-List: venturi troubles?? --> Zenith-List message posted by: Benford2@aol.com In a message dated 2/15/2004 5:00:42 PM Mountain Standard Time, jpkarnes@earthlink.net writes: > > When I have been flying lately, my gyro horizon has started tumbling after > flying about 20-30 minutes. It is connected to a 4" venturi located on the > left bottom fuse. Is it possible that the venturi is icing up and losing > vacuum? OAT has been about 40 deg F. > > John Karnes > Port Orchard, WA > N601JK > What does your suction gauge read ???? ________________________________ Message 14 ____________________________________ Time: 07:28:32 PM PST US From: Tim & Diane Shankland Subject: Re: Zenith-List: Stratus Subaru cooling --> Zenith-List message posted by: Tim & Diane Shankland Thought I might as well throw my 2 cents in. I spent most of last winter testing heater cores for my cooling system. The current discussion is not putting all the pieces together. First, for any given heat exchanger there is a relationship between the air pressure across the core the the volume of air that goes through it. It no a matter of push or pull it is a matter of differential. I order to have the required volume of air go through the heat exchanger you must have a certain pressure differential across the core. To provide that pressure you must convert the kinetic energy of the moving air to pressure, this is called pressure recovery. Likewise you must provide a path for the heated air to escape. Pressure recovery mean that the velocity of the incoming air must be slowed down , preferable without turbulence to efficiently recover the pressure. That means that that you don't make a funnel shaped scoop but the reverse, a smaller opening that enlarges to the heat exchanger. This slows the air and recovers the pressure. The amount of pressure required to move the air through the heat exchanger depends on several variables one of the most prominent ones being the thickness of the core. Automotive radiators are designed to work at relatively low speed with little pressure recovery because they are typically 3/4 inch thick, they also are quite large and perpendicular to the air stream, not a problem for a car but not good for an airplane. The heater core I am using are 1 1/2 inch thick and in my design require 3 inches of water pressure differential across the core to cool the engine. The standard Zenith system has limited pressure recovery, is located in an area of turbulence from the front landing gear and often has the exhaust and engine heat going through it. My system has the heat exchangers in the cowling. While my system is not yet flying (this summer) I have the expressions for doing the calculations if anyone is interested. Although not yet flying the physics and the field tests I have performed looked good. Tim Shankland John Karnes wrote: >--> Zenith-List message posted by: "John Karnes" > > I was under > > >>>the belief that you wanted to force all the air past the cooling coils >>> >>> >and > > >>>wanted to block the exit in the rear... >>> >>> >>> >>OOPS! The key is to GET THE BAD AIR OUT! You can't push a string. >> >>My erudite contribution. >> >>Leo Gates >> >> > >But isn't the "bad air" forced out the bottom of the rad past the cooling >coils and fins, thus creating the cooling effect you are after??? > >John Karnes > > > >