---------------------------------------------------------- Lightning-List Digest Archive --- Total Messages Posted Mon 06/25/07: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:19 AM - Re: N730AL Panel #3 and height of panel.... (nick otterback) 2. 10:37 AM - Gap Seal Application Advice (Brian Whittingham) 3. 07:02 PM - Re: N730AL Panel #3 and height of panel.... (pequeajim) 4. 08:43 PM - Re: Re: N730AL Panel #3 and height of panel.... (Mark Stauffer) ________________________________ Message 1 _____________________________________ Time: 07:19:34 AM PST US From: nick otterback Subject: Re: Lightning-List: N730AL Panel #3 and height of panel.... ________________________________ Message 2 _____________________________________ Time: 10:37:52 AM PST US From: "Brian Whittingham" Subject: Lightning-List: Gap Seal Application Advice I will post my final findings online soon. Nick is going to provide me with an airspeed calibration soon and then I'll get the rest of my results up for performance changes. Well, after talking to Earl F. this morning, we now have a second airworthy Lightning with gap seals. Unlike my previous experiment, this one is a light sport compliant Lightning aimed to improve efficiency. It is also made to be a temporary installation. There were several lessons learned during my experiment in the fabrication of the seals. I would make some changes if I were going to make a permanent installation. 1. seal length - The gap seals were mostly good, but on the flaps especially I would trim them to where they covered the majority of the hole, but didn't overlap the flaps. This way the flaps could be extended without the gap seals vibrating against the belly of the plane. I think that I'd do the same to the underside of the ailerons, although we had no problems with the ailerons. 2. cloth seals added to ailerons - I would put either an S-shaped or V shaped cloth seal in the aileron before adding the mylar seals to cover the hole. The idea is that the cloth seal would stop the airflow better and the mylar would smooth the airflow over the void. This is commonly done on gliders who need every bit of energy that they can recovered. There are two methods. One is the S - seal which looks like an S from the side. You attach it to the top of the wing, flex the aileron full travel and then attach the rear part to the bottom of the aileron. The second method is where you attach a seal to the upper and lower parts of the wing. You flex the aileron full opposite and trim to length. You then create a crease in the void area to where when the aileron is in the nuetral position it is pretty much flush across the top of the wing, but as you deflect the aileron you stretch the V shape open. I have included a graphic of this, but in my pic the V shape is open at nuetral to illustrate the shape. I believe that we would've had a much tighter seal in terms of airflow escaping from the high pressure to the lower pressure side of the wing if we had've done this one extra step. 3. Seal thickness - In our experiment we got some uneven "waiviness" in the larger seals along the bottom of the wing. This had to have cost us a little in terms of drag and if I had've had several more sets of hands and sharper eyes and lots of time we probably could've gotten the wrinkles out. The wrinkles were all spanwise and not chordwise though. I would probably go to some thicker duralar, specifically on the flaps. The longer the seal, the harder to minimize the ripples, but I believe a stiffer seal would've worked better. I believe the seals were 7/1000th's of 1 inch thick for reference. Again, Duralar is just a trademarked name for a higher tensile strength version of mylar. 4. Prepare for the unexpected - For any aircraft this is a good rule, but when modifying an experimental yourself, you're essentially retesting the flying qualities of the aircraft. I was very careful to try to take this in steps. First Nick taped up the flaps only to see what it felt like. No real change. We then put on the seals for the ailerons and elevator. Nick took another short flight and reported that it felt basically the same in terms of control pressures and handling. With my method of application though there was the possibility of one of the top aileron seals coming loose from the double sided tape, but not the 2nd layer of tape (see graphic) This has been reported on several gliders. What happens is the the front of the seal is still attached, and being on the lower pressure side of the wing it pulls up. This creates an effect like a spoiler and aileron and possibly a little rudder has to be put in to counteract the roll. I'm not sure of any accidents where this happened, but several anxious pilots. The Lightning would have more than enough aileron to counteract this problem, but it would have to be recognized and corrective action taken. Another option is a permanent installation using glue, but I'd still recommend keeping alert whenever flying. 5. Cost/Time analysis - The cost for manufacturing the seals was probably less than $100, although I haven't went back to tally up the costs. This could be manufactured in a precut and shaped kit from probably realistically $500-$750. The benefits would be tried and proven materials, instructions & pics for installation, and improved safety because of the proven installation and material methods. Time, if you had an extra person to help you would probably be around 2 hours for the install to make sure that you have it on smoothly and that it looks good and is straight. For that you get about 5 extra knots of cruise performance. If you kept your cruise speed the same as before the mod, you should get extra fuel efficiency, although I didn't test for that. It stands to reason that if your drag is decreased though that you will be able to turn higher RPMS, run at higher TAS's, and burn less fuel at a set RPM. 6. Looks - Didn't change much on the top side of the plane. Looked like a piece of white tape along the top of each wing near the aileron. If you glued it on you'd see a white rectangular strip of mylar covering up the hole which was pretty close to the same color as the plane. On the bottom I used clear gap seals across the wing and white across the tail. You could use all white or all clear. On the ground, if you looked up under there you could barely notice them, but standing out on the runway after Nick got off the ground and looking up it appeared that the gap was gone from the ground. So overall you would have negligible change in looks. Very similar to the gap seals on the aileron of the Cirrus from the top side. Overall I think that our experiment was a success. Hopefully Earl can independantly verify the results. We also got a favorable result from the experiment which means that it is potentially applicable. I did find it interesting that there's a Penn State Aero professor that had calculated that you get basically a certain percent increase in each performance field for installation of gap seals on small GA aircraft. His research led me to try out this experiment as he always meant to do a Phase II with composites (metal airplanes in his original tests). What we've seen is a greater increase in terms of performance percentages, than as calculated by his results. I'm not sure whether to attribute that to the wing planform or to that of composites (clean surface) versus a riveted metal surface. Interesting however you look at it. Brian W. _________________________________________________________________ Dont miss your chance to WIN $10,000 and other great prizes from Microsoft ________________________________ Message 3 _____________________________________ Time: 07:02:22 PM PST US Subject: Lightning-List: Re: N730AL Panel #3 and height of panel.... From: "pequeajim" Nick: You post didn't go through? Read this topic online here: http://forums.matronics.com/viewtopic.php?p=120630#120630 ________________________________ Message 4 _____________________________________ Time: 08:43:10 PM PST US From: "Mark Stauffer" Subject: RE: Lightning-List: Re: N730AL Panel #3 and height of panel.... Jim, I looked at the panel you posted and I'm concerned that you haven't taken the 2" bend at the bottom of the panel into account during your design. The reason I say this is the dimension from the top of the corners just above the fresh air vents to the bottom of the panel look too long. If I'm correct then you will lose all of you back up instruments and controls below your screens. Is your picture drawn to scale? Mark -----Original Message----- From: owner-lightning-list-server@matronics.com [mailto:owner-lightning-list-server@matronics.com] On Behalf Of pequeajim Sent: Monday, June 25, 2007 9:02 PM Subject: Lightning-List: Re: N730AL Panel #3 and height of panel.... Nick: You post didn't go through? Read this topic online here: http://forums.matronics.com/viewtopic.php?p=120630#120630 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message lightning-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Lightning-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/lightning-list Browse Digests http://www.matronics.com/digest/lightning-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.