---------------------------------------------------------- Allegro-List Digest Archive --- Total Messages Posted Tue 03/23/10: 8 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 02:02 AM - Re: Negative Flaps (aerosiam) 2. 02:26 AM - Flap failure - broken wires (aerosiam) 3. 02:36 AM - Front suspension noise (aerosiam) 4. 02:43 AM - Inner tubes (aerosiam) 5. 04:54 AM - Re: Negative Flaps (Thom Riddle) 6. 07:09 AM - Re: Flap failure - broken wires (Hugh McKay) 7. 09:01 AM - Re: Re: Negative Flaps (Brad Kramer) 8. 12:39 PM - Re: Negative Flaps (Thom Riddle) ________________________________ Message 1 _____________________________________ Time: 02:02:11 AM PST US Subject: Allegro-List: Re: Negative Flaps From: "aerosiam" My 2006 Allegro has negative flaps. A few thoughts.... The design is for neg flaps. If the flaps are set 0, then about 5 degrees is added to the flap settings (unless the microswitch positions are altered). That means take off at 20 deg not 15 which may lengthen the run. Also full would be 53 deg which suggests the Vfe should be reduced. Are the hinges etc designed to allow for that extra force with 10% more full flap? Neg flaps improve the performance by reducing drag ( exactly in the opposite way to having flaps down.) Climb, cruise, glide and economy will be better. Althoug neg flaps are more associated with gliders, more SLAs have them such as the good-performance Virus and CT2 One downside is that neg flaps reduce the washout. In theory, the aileron span will stall earlier (in a clean stall) than the flapped span because it is at a higher angle of attack. In practice, the Allegro design has enough washout built in so this does not happen. However, I fitted vortex generators to my plane with closer spacing outboard and this noticably reduced the wing drop at the stall. My suggestion is don't alter a basic design parameter. Paul Read this topic online here: http://forums.matronics.com/viewtopic.php?p=291384#291384 ________________________________ Message 2 _____________________________________ Time: 02:26:52 AM PST US Subject: Allegro-List: Flap failure - broken wires From: "aerosiam" There is a vertical post next to the flap motor with 3 microswitches to control flap travel. A computer ribbon with 9 wires is used to connect to it. I have had 2 flap failures because of broken wires. The problem is that the gage of the wire in the ribbon is very small . I fly from a grass strip that is not smooth and the solder joints can break especially the top ones which are longest and most affected by vibration. One solution is to connect the ribbon to heavier 18 gage wire and solder that to the terminals which have a hole so they can be well secured. When I checked all the joints before repairing, another joint broke just by touching it. This may be an issue for older planes or those not operating from smooth runways. Paul Read this topic online here: http://forums.matronics.com/viewtopic.php?p=291386#291386 ________________________________ Message 3 _____________________________________ Time: 02:36:45 AM PST US Subject: Allegro-List: Front suspension noise From: "aerosiam" The climate in Thailand is not good for rubber products. On our 4 year old plane, the rubber on the nose leg has worn or shrunk so there was a clonking noise whenever the suspension moved. The solution was to insert a 1 mm brass spacer ring between the rubber block and the collar underneath it. It is an easy job. After unbolting the nose fork, the rivetted collar above can be removed and the spacer inserted. Paul Read this topic online here: http://forums.matronics.com/viewtopic.php?p=291387#291387 ________________________________ Message 4 _____________________________________ Time: 02:43:01 AM PST US Subject: Allegro-List: Inner tubes From: "aerosiam" I have had problems 4 times with inner tubes. 2 punctures, 1 valve failure and 1 where the side of the tube wore through. The inner tubes are made in Vietnam and I am not sure the quality is good. I always had difficulty attaching footpump hoses to them and replaced them with new inner tubes with valves at 90 degrees which also solves the problem of getting to the the valves with wheelpants on. Paul Read this topic online here: http://forums.matronics.com/viewtopic.php?p=291388#291388 ________________________________ Message 5 _____________________________________ Time: 04:54:49 AM PST US Subject: Allegro-List: Re: Negative Flaps From: "Thom Riddle" Brad, Have you actually measured the flap position when set to "0"? When I owned N221FA I checked the flaps in "0" position and they looked slightly reflexed to me, but I didn't actually measure them. 4 1/2 degrees is pretty small amount visually on a short chord flap but enough aerodynamically on a clean airframe to make a difference. If you decide to measure them, you might want to consider putting a little upwards pressure on them when measuring to take out the slack in the control system. Not sure which way the aerodynamic forces will push them in the "0" position but a little bit of slack would affect the measurement noticeably. Unless the manual says to make this measurement by comparing to the ailerons, I think it would be more appropriate to measure against the bottom camber of the wing just ahead of the flap. One reason for this is that the aileron rigging could be uneven from one side to the other for fine tuning of roll trim. Thom -------- Thom Riddle Buffalo, NY Kolb Slingshot SS-021 Jabiru 2200A #1574 Tennessee Prop 64x32 An ounce of action is worth a ton of theory. - Friedrich Engels Read this topic online here: http://forums.matronics.com/viewtopic.php?p=291401#291401 ________________________________ Message 6 _____________________________________ Time: 07:09:25 AM PST US From: "Hugh McKay" Subject: Re: Allegro-List: Flap failure - broken wires Paul, Jim, Brad, Thom, et al, Paul, thanks for your insight concerning the negative flap question I posted. Mine will stay at 4.5 degrees negative. Concerning the broken wire problem on the electric flap drive; I too fly out of a turf runway and I have had the same broken wire problem, but only once. However, another problem that I have had is related to the screw drive for the flaps and the flexible metal plate that trips the micro switches. When the screw drive motor engages the round vertical screw housing that holds the flexible metal plate rotates slightly (slack) as the screw engages. This slight rotation of course causes the attached flexible metal plate to shift slightly. In my case this slight rotational slack caused the metal plate to shift out of position just enough to cause the micro switch to catch on the edge and bend the switch arm and break the switch. This happened two times before I figured out what was happening. The flexible metal plate was not wide enough to compensate for this rotational slack. My solution to the problem was to fabricate a wider flexible metal plate. This took care of the problem. The original tires for the Allegro 2000 are cheap thin wall tires that have poor rigidity, and yes the inner tubes are poor quality. I have had only one flat tire in 3 years of flying, and that was a slow leak down over night while sitting in the hanger. Thank goodness it was slow and while I was on the ground. After taking the tire off and checking the tire and tube I found that the side wall of the tire was cracked in three small places at the points where the tire mould came together to form the outer shape of the tire. One of the other tires was also beginning to crack at the mould seams. This slight crack, combined with the already weak side wall strength which allowed the tire itself to flex more than it should on normal on landings, created a situation that allowed a slight pinching to occur on the inner tube where the crack was located. This flexing of the side wall, the slight crack in the side wall, and the resulting minute pinching on the inner tube over time worked it's way through the tube resulting in the final leak down over night. As a result of this I changed all of my tires to 8 ply tires with tubes. I suggest that everyone who has the original tires on their Allegro check them carefully and on a regular basis before every flight. If you find any visible cracking of the side wall, get new tires! Hugh McKay Allegro 2000 Rotax 912 N661WW -------------------------------------------------- From: "aerosiam" Sent: Tuesday, March 23, 2010 5:26 AM Subject: Allegro-List: Flap failure - broken wires > > There is a vertical post next to the flap motor with 3 microswitches to > control flap travel. A computer ribbon with 9 wires is used to connect to > it. > I have had 2 flap failures because of broken wires. > > The problem is that the gage of the wire in the ribbon is very small . I > fly from a grass strip that is not smooth and the solder joints can break > especially the top ones which are longest and most affected by vibration. > > One solution is to connect the ribbon to heavier 18 gage wire and solder > that to the terminals which have a hole so they can be well secured. > > When I checked all the joints before repairing, another joint broke just > by touching it. This may be an issue for older planes or those not > operating from smooth runways. > > Paul > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=291386#291386 > > > ________________________________ Message 7 _____________________________________ Time: 09:01:19 AM PST US From: "Brad Kramer" Subject: Re: Allegro-List: Re: Negative Flaps Hi Thom, Somehow I just KNEW I should ask you about our plane, instead of firing o ff answers when I'm in a hotel and not at the airport. You're right... 4. 5 degrees is very little to see given the length of the flaps. So... Hugh , let me retract my answer and defer to others who have actually made som e measurements. Thom... hoping you make it to OSH. I'm 80% sure I'll be there working dep arture briefings and being a tent rat again. (Hopefully with the Allegro, instead of Delta Airlines). ...brad. -----Original Message----- From: Thom Riddle [mailto:riddletr@gmail.com] Sent: Tuesday, March 23, 2010 06:54 AM Subject: Allegro-List: Re: Negative Flaps measured the flap position when set to "0"? When I owned N221FA I checke d the flaps in "0" position and they looked slightly reflexed to me, but I didn't actually measure them. 4 1/2 degrees is pretty small amount visu ally on a short chord flap but enough aerodynamically on a clean airframe to make a difference. If you decide to measure them, you might want to c onsider putting a little upwards pressure on them when measuring to take out the slack in the control system. Not sure which way the aerodynamic f orces will push them in the "0" position but a little bit of slack would affect the measurement noticeably. Unless the manual says to make this me asurement by comparing to the ailerons, I think it would be more appropri ate to measure against the bottom camber of the wing just ahead of the fl ap. One reason for this is that the aileron rigging could be uneven from one side to the other for fine tuning of roll trim. Thom -------- Thom Ri ddle Buffalo, NY Kolb Slingshot SS-021 Jabiru 2200A #1574 Tennessee Prop 64x32 An ounce of action is worth a ton of theory. - Friedrich Engels Rea d this topic online here: http://forums.matronics.com/viewtopic.php?p=2 ============= ________________________________ Message 8 _____________________________________ Time: 12:39:41 PM PST US Subject: Allegro-List: Re: Negative Flaps From: "Thom Riddle" Hi Brad, Now my curiosity has been piqued. When you get back home and have a chance, it would be nice to know if your Allegro does have reflexed flaps as I suspect it does. Without a digital angle instrument it is very easy to determine the reflex (if any) by simply measuring the distance from the top of a straight edge laid along the bottom camber of the wing up to the trailing edge of the flap. That divided by the chord of the flap gives you sine of the angle you are looking for. Arcsine of that number gives you the angle. It would not surprise me to learn that there is some difference between the two flaps because that is another way to adjust roll trim. Thom -------- Thom Riddle Buffalo, NY Kolb Slingshot SS-021 Jabiru 2200A #1574 Tennessee Prop 64x32 An ounce of action is worth a ton of theory. - Friedrich Engels Read this topic online here: http://forums.matronics.com/viewtopic.php?p=291465#291465 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message allegro-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Allegro-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/allegro-list Browse Digests http://www.matronics.com/digest/allegro-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.