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<DIV>Troy,</DIV>
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<DIV>I agree with your analysis 100%. Pat and I fly the Abbra. These models were originally set at 0.75 degree positive incidence with no adjusters. I decided to install adjusters this winter in order to have the full flexibility as you explained. I have had the same experience in regard the incidence and I usually finish with 0.25 degrees. Pat's Abbra could be OK since is gas engine and it is heavier.</DIV>
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<DIV>Now you can order the Abbra at 0, 0.25, 0.5 and 0.75 degrees. I think it is better to go 0 or 0.25 if you use glow engine.</DIV>
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<DIV>Thanks,</DIV>
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<DIV>Vicente Bortone</DIV>
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<DIV> </DIV>
<BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #1010ff 2px solid">-------------- Original message -------------- <BR><BR>> Pat, <BR>> <BR>> to give an answer that you don't want to hear... <BR>> <BR>> We have no idea. The model design will determine it. All the factors <BR>> mentioned from RVP are correct. Also the fuse shape. If the shape is such as <BR>> the model looks like its flying tail down then it needs more positive in the <BR>> wing. Also trim considerations, however I don't try to trim knife edge using <BR>> the wings. I'll leave that to the experts here on the list. I set the <BR>> incidence in the wing to make the fuse sit properly in the air. <BR>> <BR>> A rule of thumb I use is I will set the fuse up with its flying line (datum <BR>> line, zero line what ever) at zero deg to mother earth. I use a digital <BR>> smart level. I then walk across the room or down the hall. If the model <BR>> looks good as in its sitting what my eye perceives as level...I set the <BR>> incidence 0.25 to 0.5 deg to that. I usually start at 1/4 deg and know that <BR>> I will be cranking more positive in it. <BR>> <BR>> I know you said that adjustable is not in the cards. OK that doesn't mean <BR>> you can't adjust it later depending how they did it. If pins in the wings <BR>> and sockets in the fuse. You move the sockets. All it takes is a little move <BR>> and things change. <BR>> <BR>> <BR>> The criteria I use when flying will depend on what its doing in the air. If <BR>> it still looks tail low while flying level I'll crank in some more positive. <BR>> If it looks level and say it is pulling slightly on upline I might crank in <BR>> positive to see if the upline gets fixed and it doesn't disturb other things <BR>> like power off downlines, or elevator trim. My opinion is a model flies <BR>> better with a little positive in the wing. I tend to fly models that are <BR>> more nose heavy than other people the
result is the positive needs to be <BR>> there. And it helps the model track better. I will say this as you move the <BR>> CG aft to amore neutral location as in no elevator inverted and so on...The <BR>> need for positive incidence gets reduced. Also the need for thrust offsets <BR>> gets reduced. But in this config I have yet to get a model to fly in a <BR>> straight line. It might do OK when calm but a tail heavy model (more <BR>> neutral) will be a bear in the wind. I flew my Father in Laws Focus and the <BR>> guys were running the CG up at the front edge of the wing tube. I couldn't <BR>> get the model to settle down until it was almost a full inch ahead of the LE <BR>> of the tube. Then the model tracked like I thought it should. I spoke with <BR>> Don Sczur about his and he had the CG way up forward too. <BR>> <BR>> I believe in providing the model with a Bias so that it tracks on its own. <BR>> This is the way I was taught to do it. Pull the corner and let go. The model <BR>> should do the work for you. <BR>> <BR>> I would say I usually end up with about 0.25 to 0.5 degs of incidence in all <BR>> my models. I could not tell you how much because I don't know where the <BR>> flying line really is on some of them. The ZN Supreme I know where it is as <BR>> a flying line and I know I started with exactly 0.25deg and I cranked more <BR>> positive in it. How much? Oh about a turn or two until I liked the way it <BR>> tracked. <BR>> <BR>> The other great reason for adjusters is to eliminate aileron trim. If you <BR>> are carrying aileron trim it will be a speed sensitive thing and this will <BR>> not help you at all. You'll have to create a thro to aileron mix to <BR>> eliminate it. <BR>> <BR>> Heck guys do it and beat me with that setup. But it just doesn't work for <BR>> me, I get the model to fly straight in roll with zero aileron trim with the <BR>> adjusters. Sometimes is a 1/4 turn on a 4-40 bolt and sometimes its mo
re <BR>> like a full turn. If the model is flying tail low or is pitching slight to <BR>> canopy in the upline I might crank just one wing positive. This acts to zero <BR>> out the roll and also increase the positive in the wing as a whole. Then <BR>> sometimes I'll throw in a gob of positive on one side and a smidge on the <BR>> other to raise the tail and also eliminate aileron trim needs. Adjusters are <BR>> a wonderful trim tool. <BR>> <BR>> On big IMAC airplanes we adjust the incidence too. Just sand the socket and <BR>> little ovaled and then put a new ply ring on the inside. Works wonders in <BR>> some case. Other cases the problem doesn't go away and we fix it with thrust <BR>> or the tail or who knows what else. <BR>> <BR>> <BR>> I have flown a bunch of models in the last few years looking for that <BR>> perfect one. If you email me which one I might be able to help you out. <BR>> <BR>> Troy <BR>> <BR>> <BR>> <BR>> ----- Original Message ----- <BR>> From: "Pat Hewitt" <PHEWITT@FARMERSAGENT.COM><BR>> To: <JONLOWE@AOL.COM>; <DISCUSSION@NSRCA.ORG><BR>> Sent: Friday, September 30, 2005 9:53 AM <BR>> Subject: INCIDENCE settings <BR>> <BR>> <BR>> I would like to learn more about incidence settings on our wings. I have a <BR>> chance to buy a plane that has preset settings such as O, .25, .50, or .75 <BR>> but <BR>> how do I make the correct choice. I am sure the best is to have an just able <BR>> system but please lets not go there I just want to understand how you pick <BR>> the <BR>> correct one. <BR>> <BR>> Thanks <BR>> <BR>> Pat Hewitt <BR>> Paola, Ks. <BR>> <BR>> <BR>> <BR>> <BR>> <BR>> <BR>> ------ Original Message ------ <BR>> Received: 11:35 AM CDT, 09/30/2005 <BR>> From: jonlowe@aol.com <BR>> To: discussion@nsrca.org <BR>> Subject: Backplate Pump for OS 1.60 <BR>> <BR>> After seeing the discussion about putting an OS 1.40 pump in the <BR>> back
plate of an OS 1.60, I got to thinking. The OS 1.40 pump/backplate <BR>> is over $150 from Tower, then you have to get a special 1.60 backplate <BR>> for another $100 or so. In the old days, Perry made special backplates <BR>> with integral pumps for .61s. I had one with a bad pump. Perry <BR>> doesn't make the backplates anymore, but they put in a new pump in my <BR>> backplate for less than $50. As long as we are thinking about making <BR>> up special backplates, what about copying the old .61 design for the <BR>> 1.60, and sending them to Perry to have pumps put in? This would <BR>> certainly clean up the installation of the 1.60, eliminate a couple of <BR>> failure points for the separate pump setup, and be a lot cheaper than <BR>> using the 1.40 pump. I have a couple spare old Perry backplates that <BR>> could be used as samples for a machinist that I'd be willing to loan <BR>> out. Anyone willing to take this on? <BR>> <BR>> Jon Lowe <BR>> ================================================= <BR>> If you want your reply email to go to the list, you must Cc: the list! <BR>> <BR>> To access the email archives for this list, go to <BR>> http://lists.f3a.us/pipermail/nsrca-discussion/ <BR>> To be removed from this list, go to http://www.nsrca.org/discussionA.htm <BR>> and follow the instructions. <BR>> <BR>> List members email returned for mailbox full will be removed from the list. <BR>> <BR>> <BR>> <BR>> <BR>> <BR>> ================If you want your reply email to go to the list, you must Cc: <BR>> the list! <BR>> <BR>> To access the email archives for this list, go to <BR>> http://lists.f3a.us/pipermail/nsrca-discussion/ <BR>> To be removed from this list, go to http://www.nsrca.org/discussionA.htm <BR>> and follow the instructions. <BR>> <BR>> List members email returned for mailbox full will be removed from the list. <BR>> <BR>> ================================================= <BR>> If you
want your reply email to go to the list, you must Cc: the list! <BR>> <BR>> To access the email archives for this list, go to <BR>> http://lists.f3a.us/pipermail/nsrca-discussion/ <BR>> To be removed from this list, go to http://www.nsrca.org/discussionA.htm <BR>> and follow the instructions. <BR>> <BR>> List members email returned for mailbox full will be removed from the list. <BR>> </BLOCKQUOTE></body></html>