---------------------------------------------------------- Zenith-List Digest Archive --- Total Messages Posted Fri 11/14/08: 13 ---------------------------------------------------------- Today's Message Index: ---------------------- 0. 12:17 AM - Fund Raiser Lagging Last Year By Over 30%... (Matt Dralle) 1. 07:11 AM - Re: Zenith-List Digest: 41 Msgs - 11/12/08 (mversteeg) 2. 07:24 AM - Re: Heavy engine and Horiz. stab (Sabrina) 3. 08:34 AM - Re: Heavy engine and Horiz. stab (Bryan Martin) 4. 08:57 AM - Re: Re: Zenith-List Digest: 41 Msgs - 11/12/08 (Paul Mulwitz) 5. 11:54 AM - Mean Aerodynamic Chord (George Swinford) 6. 12:23 PM - Re: Mean Aerodynamic Chord (steve) 7. 01:21 PM - Re: Re: Cable Tensions for 601XL? (JAPhillipsGA@aol.com) 8. 06:27 PM - Re: 601XL Wing Flutter (David X) 9. 07:04 PM - Re: Re: 601XL Wing Flutter (steve) 10. 08:30 PM - 601XL - Aileron Trim Tab Deflection (Dave VanLanen) 11. 09:39 PM - Re: 601XL - Aileron Trim Tab Deflection (Ron Lendon) 12. 10:47 PM - I've moved to FLAG (and you can too) (Richard Vetterli) ________________________________ Message 0 _____________________________________ Time: 12:17:15 AM PST US From: Matt Dralle Subject: Zenith-List: Fund Raiser Lagging Last Year By Over 30%... As of the 13th, the Fund Raiser is currently about 30% behind last year in terms of the number of Contributions. Yet, oddly the number of messages posted per day is up by 10 to 20% on the average. It costs real money to run these Lists and they are supported 100% though your Contributions during the Fund Raiser. Won't you please take a minute right now to make your Contribution to keep these Lists up and running? Contribution Page: http://www.matronics.com/contribution Thank you for your support! Matt Dralle Email List Admin. ________________________________ Message 1 _____________________________________ Time: 07:11:41 AM PST US From: mversteeg Subject: Zenith-List: Re: Zenith-List Digest: 41 Msgs - 11/12/08 Hello Paul, I agree, and although complex panels seem to attract some, I like the clean panels. I also know that experimental - amateur built airplanes don't fall under all the rules. But on the other hand I have heard stories where the DAR sometimes is very specific (remember the whiskey compass discussion). I hope you will have a DAR that accepts this and sees the sense of you argument. Regards, Maarten, plans building XL, getting close to closing the second wing > Time: 08:03:02 AM PST US > From: Paul Mulwitz > Subject: Re: Zenith-List: Wires and fuses and such > > > Hi Maarten, > > I guess the regulation you cited explains why so many panels are > crowded with circuit breakers. In their great wisdom, the FAA seems > to have dictated that solution. > > Fortunately, I don't think part 23 regulations apply to experimental > - amateur built airplanes. This may be one of many examples of the > notion that the FAA regulations are overly restrictive on certified planes. > > To directly answer your question, my plans are to limit my flights to > Day/VFR. I suspect I could safely conduct such flights without any > electrical equipment operating at all. The only really essential > piece of electrical gear is the starter motor. My Jabiru is not > likely to start any other way. > > Best regards, > > Paul ________________________________ Message 2 _____________________________________ Time: 07:24:51 AM PST US Subject: Zenith-List: Re: Heavy engine and Horiz. stab From: "Sabrina" Grant, You have an HDS. Bryan, Scott and I used XL plans or kit. From my comparison of the HDS vs. XL, the XL decreased the decalage. Then the 650 increased the decalage. All Bryan, Scott and I did was increase the decalage of our aircraft to a range similar to that built into your HDS and the new 650s. The factory shifts the wing, we shift the H stab. Other than an HD series used for aerobatics, I don't know of a single 600 series with the increased (I would call nominal) decalage that has had a structural failure. We have had this argument before, but it was prior to the increase in the 650's decalage. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=214193#214193 ________________________________ Message 3 _____________________________________ Time: 08:34:02 AM PST US From: Bryan Martin Subject: Re: Zenith-List: Heavy engine and Horiz. stab I agree with you on all counts but, the airplane also has to be built with the proper decalage between the wing and stabilizer. In my case, the CG was within the acceptable range and I still could not trim it out. With the CG near the aft limit I was just able to trim it with full tab deflection. With my aerospace engineering education, I determined that the solution to this situation was to re-pitch the stabilizer. I had somehow got the decalage slightly off during construction. It worked and my test flights after the correction showed the airplane had adequate pitch stability. If we were all building our airplanes in identical rigging fixtures they would all be rigged the same. Since each one is hand built by a different individual, you can expect slight differences in the final product. It should be no surprise that the need for some small corrections might be found during the phase 1 testing. On Nov 13, 2008, at 9:05 PM, Frank Roskind wrote: > A heavy engine does not require more down force on the elevator if > the plane is balanced correctly.. A properly balanced standard > configuration airplane needs a center of mass ahead of the center of > lift, which would produce a nose down pitching force if there were > no force applied from the horizontal stabilizer and elevator. The > Horizontal empennage surfaces provide a downward force in order to > keep rotational forces in balance. When that force is diminished > the nose pitches downward, which is what happens to a stable > airplane in a stall. The center of mass should always be in a range > relataive to the datum which keeps the Center of Mass in front of > the center of lift by a small margin. Too great a margin will mean > that the plane will be difficult to fly and may not even rotate for > takeoff. Further, the stall speed is raised as the Center of Mass > moves forward, because the lifting surface must offset the downward > force at the tail. > > You need to build your airplane so the Center of Mass is within the > designer's specs. You can do that by moving the engine closer to > the firewall, if possible, or by putting wieghts in the rear of the > aircraft. It is better that the weight come from equipment, but the > weight could also come from mere ballast. If you move your engine > back, you may need to add some kind of spacer for the propeller for > better handling and performance. > > In my opinion it would be dangerous for a non-expert simply to make > the tail surfaces larger, or to pitch them at a steeper downward > angle, to offset the weight of an engine. If you intend to do > something like that please consult with Zenith first, for your own > safety. > -- Bryan Martin N61BM, CH 601 XL, RAM Subaru, Stratus redrive. ________________________________ Message 4 _____________________________________ Time: 08:57:08 AM PST US From: Paul Mulwitz Subject: Re: Zenith-List: Re: Zenith-List Digest: 41 Msgs - 11/12/08 Hi Maarten, I don't want to get into a regulation interpretation battle, but I will if I must. As I understand the regs and DAR history, the compass issue is completely separate from the part 23 question. Part 23 clearly doesn't apply to Experimental airplanes. Experimental airplanes do require a compass. The issue I have heard discussed is whether the compass must be a whiskey compass or if one of the new-fangled electrical devices like the one found on the Dynon EFIS is sufficient to meet this need. I think the electrical compass is really satisfactory to meet the requirements, but some builders have run into this issue with their DAR and decided a cheap automotive whiskey compass was an easy way to get past an old fashioned DAR. From a strictly practical point of view, it makes sense that you need to be able to figure what direction you are going under all circumstances - including electrical failure. The same argument doesn't apply to trying to trouble-shoot electrical problems while still in flight. Best regards, Paul XL getting close At 07:10 AM 11/14/2008, you wrote: >Hello Paul, > >I agree, and although complex panels seem to attract some, I like the clean >panels. I also know that experimental - amateur built airplanes don't fall >under all the rules. But on the other hand I have heard stories where the DAR >sometimes is very specific (remember the whiskey compass discussion). >I hope you will have a DAR that accepts this and sees the sense of you >argument. > >Regards, > Maarten, > plans building XL, getting close to closing the second wing ________________________________ Message 5 _____________________________________ Time: 11:54:00 AM PST US From: "George Swinford" Subject: Zenith-List: Mean Aerodynamic Chord John Read, and others: "Mean Aerodynamic Chord" is a length, rather than a point. For an untapered wing, the MAC is the length of the chord measured anywhere along the span. For a tapered planform the MAC is found at a spanwise location where the chord is sort of an average of all the chord lengths. On a wing with simple taper this is easily determined. For a planform with sweep and multiple tapers, typical of modern airliners, it becomes a bit more complicated. I think the point to which you refer is the so-called "aerodynamic center", which is found on the MAC at a distance equaling approximately 25 percent of the MAC aft of the leading edge. The acceptable range of center of gravity locations is usually expressed in percent of MAC; for a particular airplane it might be from 10 percent to 30 percent. The acceptable CG range depends on a number of design features, one of the most powerful being the tendency of the wing to pitch or rotate about its spanwise axis. This tendency must be counteracted by other forces on the airplane, largely by a down force generated by the horizontal tail. The popular old NACA 23000 series airfoils (23012, 23015 etc) were designed to have a low pitching moment. Symmetrical airfoil sections (for example 23000) have zero pitching moment and have often been used on helicopter blades and aerobatic airplanes for that reason. Incidentally, "symmetrical" means identical, top and bottom. Some refer to an airfoil as symmetrical just because it has some curvature on the lower surface, but this is incorrect. You are correct in noting that flying wings typically use an airfoil section which has a reflexed trailing edge. This reduces the pitching tendency to near zero and deflection of the trailing edge surfaces does the rest. You are also correct in noting that changing the incidence of the stabilizer is not the way to correct a static balance situation, although it will have an effect on the overall static stability. I hope this helps generate light, rather than heat. George ________________________________ Message 6 _____________________________________ Time: 12:23:10 PM PST US From: "steve" Subject: Re: Zenith-List: Mean Aerodynamic Chord Right On ! ----- Original Message ----- From: George Swinford To: zenith-list@matronics.com Sent: Friday, November 14, 2008 12:52 PM Subject: Zenith-List: Mean Aerodynamic Chord John Read, and others: "Mean Aerodynamic Chord" is a length, rather than a point. For an untapered wing, the MAC is the length of the chord measured anywhere along the span. For a tapered planform the MAC is found at a spanwise location where the chord is sort of an average of all the chord lengths. On a wing with simple taper this is easily determined. For a planform with sweep and multiple tapers, typical of modern airliners, it becomes a bit more complicated. I think the point to which you refer is the so-called "aerodynamic center", which is found on the MAC at a distance equaling approximately 25 percent of the MAC aft of the leading edge. The acceptable range of center of gravity locations is usually expressed in percent of MAC; for a particular airplane it might be from 10 percent to 30 percent. The acceptable CG range depends on a number of design features, one of the most powerful being the tendency of the wing to pitch or rotate about its spanwise axis. This tendency must be counteracted by other forces on the airplane, largely by a down force generated by the horizontal tail. The popular old NACA 23000 series airfoils (23012, 23015 etc) were designed to have a low pitching moment. Symmetrical airfoil sections (for example 23000) have zero pitching moment and have often been used on helicopter blades and aerobatic airplanes for that reason. Incidentally, "symmetrical" means identical, top and bottom. Some refer to an airfoil as symmetrical just because it has some curvature on the lower surface, but this is incorrect. You are correct in noting that flying wings typically use an airfoil section which has a reflexed trailing edge. This reduces the pitching tendency to near zero and deflection of the trailing edge surfaces does the rest. You are also correct in noting that changing the incidence of the stabilizer is not the way to correct a static balance situation, although it will have an effect on the overall static stability. I hope this helps generate light, rather than heat. George ________________________________ Message 7 _____________________________________ Time: 01:21:09 PM PST US From: JAPhillipsGA@aol.com Subject: Re: Zenith-List: Re: Cable Tensions for 601XL? Jay, thanks for the info. I finished my XL over three years ago and built the tail feathers back in '03 so I don't remember this. I need to check my plans and look to see if I did this mod. Thanks, Bill of Georgia do not archive **************Get the Moviefone Toolbar. Showtimes, theaters, movie news & p://toolbar.aol.com/moviefone/download.html?ncid=emlcntusdown00000001) ________________________________ Message 8 _____________________________________ Time: 06:27:01 PM PST US Subject: Zenith-List: Re: 601XL Wing Flutter From: "David X" I wonder if you have verified the cable tensions for your ailerons. This seems to be a focus of concern with the NTSB regarding at least one recent 601XL crash. -------- Zodiac 601 XL - CZAW Built - Rotax 912S DO NOT ARCHIVE Read this topic online here: http://forums.matronics.com/viewtopic.php?p=214298#214298 ________________________________ Message 9 _____________________________________ Time: 07:04:02 PM PST US From: "steve" Subject: Re: Zenith-List: Re: 601XL Wing Flutter Bill, isnt 140 a little fast for the 601 ? especiall in rough air.. Also read the CFRs about flying near power stations..... ----- Original Message ----- From: "David X" Sent: Friday, November 14, 2008 7:26 PM Subject: Zenith-List: Re: 601XL Wing Flutter > > I wonder if you have verified the cable tensions for your ailerons. This > seems to be a focus of concern with the NTSB regarding at least one recent > 601XL crash. > > -------- > Zodiac 601 XL - CZAW Built - Rotax 912S > DO NOT ARCHIVE > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=214298#214298 > > > ________________________________ Message 10 ____________________________________ Time: 08:30:37 PM PST US From: "Dave VanLanen" Subject: Zenith-List: 601XL - Aileron Trim Tab Deflection I just finished installing my aileron trim, and when I tested it, I can only get a total of 40 degrees of deflection. According to the plans, I should be able to get 50 degrees of deflection (25 up and 25 down). Adjusting the length of the control rod only changes the distribution of the 40 degrees between up and down - it does not increase the total deflection. I checked that the servo was working correctly, which it was (.7" travel per specs). I also checked that there was no binding of the control rod clevis with the trim tab horn angle. The only thing I could find was that the center of the control rod mounting hole in the horn angle was 13 mm up from the flange instead of the 12 mm specified in the plans. I find it hard to believe that 1 mm would cause a 10 degree loss in deflection. Has anyone else experienced this problem, and if so, what did you do to resolve? Thanks, Dave Van Lanen 601XL - tail done, flaps done, working on ailerons ________________________________ Message 11 ____________________________________ Time: 09:39:19 PM PST US Subject: Zenith-List: Re: 601XL - Aileron Trim Tab Deflection From: "Ron Lendon" Looks like the difference between 12mm and 13mm would be about 1.7 degrees at the .7 travel. I didn't calculate what it would be out at the tip of the trim tab, don't have the dimension handy. -------- Ron Lendon, Clinton Township, MI Corvair with Roy's Garage 5th bearing Zodiac XL, ScrapBuilder ;-) http://www.mykitlog.com/rlendon Read this topic online here: http://forums.matronics.com/viewtopic.php?p=214324#214324 ________________________________ Message 12 ____________________________________ Time: 10:47:47 PM PST US From: Richard Vetterli Subject: Zenith-List: I've moved to FLAG (and you can too) Attention Northern California (SF Bay Area) builders. After building in my garage for the past four years, I've moved my project to "First Light Aviation Group" (FLAG) in Livermore, California, adjacent to the Livermore Airport (lvk). FLAG has individual building bays, each one complete with plenty of power, compressed air, large locking tool boxs, work tables, shelves and a pallet rack for large parts. FLAG also supplies large tools (drill press, shear, brake, etc) with convenient bathrooms, vending machines, fridge and microwave. And, it's available 24/7. In the lobby is a retail store with pilot supplies and building supplies. A large meeting room upstairs rounds out the facility. I found that when I moved my airplane to FLAG, I was able to work in the company of fellow builders/pilots and without the distractions of building at home. Now I'm confident that I'll get my plane flying in short order. No one asked me to post this and I'm not affiliated with FLAG, I'm just a happy customer. Check it out at www.flaglvk.com Rich Vetterli 601XL/Corvair 95% done, 95% to go Check out my progress at www.geocities.com/stixx5a ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message zenith-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Zenith-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/zenith-list Browse Digests http://www.matronics.com/digest/zenith-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.