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General control line discussion => Open Forum => Topic started by: Greg Hart on February 24, 2014, 10:57:46 PM
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Hi guys,
What formula would one take to use a 40 size set of plans and turn it into a 60 size ship.
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Hi guys,
What formula would one take to use a 40 size set of plans and turn it into a 60 size ship.
Given that we have run the same airplanes we used to fly with ST46 on anything from 36s to 75's, that's a hard question. Which 40 and which 60? They easily overlap each other in power.
To first approximation, find an airplane that works well with whatever 60 you want to use, and make your airplane about the same size.
Brett
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All I do is decide what I want the wingspan to be, figure out the percentage increase needed to get there, and then have Kinko's copy/print an enlarged set of plans. What model design are you wanting to enlarge?
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I am thinking whatever the squares are you might ad 10% to the equation not sure. Thinking about a JD Falcon. I'm using a LA .46. Thinking about a RO-Jett .61
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I am thinking whatever the squares are you might ad 10% to the equation not sure. Thinking about a JD Falcon. I'm using a LA .46. Thinking about a RO-Jett .61
RO-Jett 61 - ~650-675 square inches. The JD Falcon is what, about 575 or so? That's about 117% larger in terms of area. Take the square root of 1.17, which is 1.08, or 108% scale up of the linear dimensions. So make all the lengths and widths about 1.08x the original dimensions.
Brett
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Greg...
You have to ask questions about what you want to achieve in the "new design".. if it is just the "look" that is excellent because an exact scale up probably work... but you will be faced with dimensional problems..
I have blown up and shrunk (some didn't fly very well) many planes.. there is the factor of balsa dimensions ... but you can get a rough idea. For me, it has always been a marriage of ideas stolen and then adapted. The moment arms are going to expand at the same percentage as the say the wing area and you may not want that. My best plane that I resized was a New Era 111 scaled down for an OS 10FSR RC... as I went along I increased the rudder size, also take off in hot weather with a full tank was interesting, it did well in cooler temps.. exact scale wasn't effective.. I am thinking of blowing up the Dolphin for the LA 46 ... from 510 sqs and 49" ws by say 15% and that would make the wing area about 586 with a ws of about 56" ... what happens with this plane as you go up in percentage is the wing length starts to not match the area.. @ 18% the area becomes about 600sq and the ws is about 58" IMO the wing area should be in the 640 to 680 range... also 3 " flaps become 3.5"... everything becomes relative.
I use a percentage wheel ..Kinkos may have one. Also paper size .. you may have to put the wing on one piece of paper and the fuse on another..
I have blown up many old designs from Flying Models.. 1/4 = 1" scale is in the 400% (ball park) If the wing area is 600 sq/in.. 10% will be 660 sqs
I find it easier to make plans from 1/4" scale drawings vs blowing up full sized plans even bigger... in this case I would scale the 1/4" scale plans up say 10-20% and then enlarge those for my final copies since the machine at Kinko's won't go over 400% ... the better detailed plans blow up just fine.. some plans have scales and others don't. I use the spinner, wheels, wing span and any other dimensions I can to get a true representation of the percentage I need to enlarge the plans... believe me when I say this... wheels might say 2" on the magazine plans but when using the scale on some plans I have found some to be smaller than the listed size.. never trust old magazine plans completely..
I have noticed some plans list the ws as 51 " and another 52" and another @ 53.5" for the Jay Dee Falcon...strange (have mistakes been made figuring the percentage?) All of these plans were enlarged from the 1961 Article in MAN...
What is probably going to happen is you will get an airfoil that is too big/thick.. a nose that may be too long... the wing tips will even be big ... ect... your wing and tail feathers "looking down on the plan" will be fine but everything else will have to modified.. use the Cardinal, Magnum, KA 10... for references... these are basic designs that you can take to the bank. Just tweak your new plans ... I usually start with the airfoil and body sides... you will also need to scale the body width to fit your engine.. once you blow up a set of plans you will see what I am talking about... I know a lot of us dream ... it's fun.
Jim
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Brett's numbers work right. It's not really that much a jump. Trust the Kinkos camera to scale it all correctly and the only thing you may need to adjust is motor mount spacing. If you start playing with dimensions it's no longer a JD Falcon and won't fly like one. Sounds like a good project.
Dave
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One problem with using the Kinko's machines to enlarge plans. Sometimes, they are not well calibrated. When enlarging, dimensions across the X-axis may be different than the same dimension across the Y-axis. This does not always happen, it just depends on how well the machines are calibrated, and my experience with their service people behind the counter is they cannot do much about it. The distortion is generally not great and for our stunt models, there is little impact, particularly if the increase is in the +10% range or so. However, if you are enlarging a set of scale 3-views or plans from a magazine page to a usable size for your model, the distortion can bean an "annoyance".
A better solution then would be to go to a print shop. Here, with the right machines and operators, they can adjust the X and Y axis dimensions to suit whatever you are looking for. (Useful when enlarging a set of 3-views for a semi-scale stunt ship where the designer might want to slim down the fuselage.)
Keith
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Another idea. Blow up the plans to get the general out line of the J.D. Falcon. Top and Side views. THEN you call your friend here in Portland and get Pattermaster foam wing cores THEN WE can work on the moments. Just an Idea.
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THEN WE can work on the moments.
Moments? Howard, he said moments.
I have one text book that defines that a moment is the product of the resultant force and a length or lever arm
Keith
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Build an Impact, paint it to match your JD Falcon, put "JD Falcon" on the left wing. Problem solved. y1 Steve
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Another idea. Blow up the plans to get the general out line of the J.D. Falcon. Top and Side views. THEN you call your friend here in Portland and get Pattermaster foam wing cores THEN WE can work on the moments. Just an Idea.
I would pick something better than the Patternmaster airfoil.
Brett
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Brett I was kinda flirting with the idea of building a Pattern Master. Is there something wrong with that Airfoil?
Mike
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Brett I was kinda flirting with the idea of building a Pattern Master. Is there something wrong with that Airfoil?
Mike
By current standards it doesn't seem to be very effective for the volume (weight) and gigantic flaps. Phil Granderson's airfoil is something like 1/3 the thickness and can handle the same or higher wing loading, without all the drag and weight. The Patternmaster as a package is pretty good, maybe one of the better ST60 planes, where the drag is probably to your advantage, but i wouldn't copy the airfoil given current knowledge.
If you build a Patternmaster, build it *straight off the plans*, don't make a modified Patternmaster. The original airplane, properly trimmed and powered, works very well, based on the examples I have seen. Mike Roger's Patternmaster from the 93 NATS looked to be outstanding. Most of the knock-offs were not nearly as good, and many of them ended up trimmed very poorly (maybe because the owners got tunnel vision on the rudder adjustments, and forgot everything else).
Brett
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Wasn't the late Bob Baron's Patternmaster built straight off the plans, the year he won the NATS finally?
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Wasn't the late Bob Baron's Patternmaster built straight off the plans, the year he won the NATS finally?
Not exactly but it was pretty close. Mike Rogers was Bob's flying buddy so he knew what to do.
The airplanes (any of them) are package deals, change some things or adapt them, and you are on your own.
There's a bizarre rumor that everything flying today is a "modified Patternmaster", promoted by the New Jersey usual suspects. I have been accused many times of "not giving Big Jim credit" for that fact that I copied it and called it an Infinity, and I know that others have been accused of the same thing. Given that many of us had never seen the plans or anything else about it until long after we had done something else, I know it was NOT copied from anything. But it is a point of irritation, and the mere fact that I am denying it here will be interpreted as "trashing Big Jim".
If someone is going to design a new airplane, I think it is worth looking into all the current options, some of which have been proven more effective since the 80s.
Brett
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There will be nothing wrong with the Patteren Master Wing. It will give Greg what he wants. IF Greg fly's 20 times a year he'll be happy.
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Thank you Brett. I have a copy of the original plans. It even has some of Big Jim's writing on it.
Mike
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Talked to Greg today. Showed him sheet wings, SV22, Pattern Master. He wants to hand cut, and take his time. IT'S A PROJECT.... y1
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I am thinking of blowing up the Dolphin for the LA 46 ... from 510 sqs and 49" ws by say 15% and that would make the wing area about 586 with a ws of about 56" ... what happens with this plane as you go up in percentage is the wing length starts to not match the area.. @ 18% the area becomes about 600sq and the ws is about 58" IMO the wing area should be in the 640 to 680 range... also 3 " flaps become 3.5"... everything becomes relative.
You have made some good points. However, the above is incorrect. While it is true that increasing the 49" span by 15% will make it about 56", the area will increase from 510 sq in to 674 1/2 sq in, rather than 586. Area increases as the square of the dimension. So your new area is 1.15 x 1.15 x 510 sq in = 1.3225 x 510 sq in = 674.475 sq in. Likewise, increasing the plan size by 18% will give you 39% more area, or about 710 sq in. These are pretty big planes for an LA .46.
You're right about scaling large amounts though. If you don't scale the circle, speeds, and turn radii to match, things aren't as likely to work the same. Scaling weights and power" (in the real sense) are not the same (e.g. material thicknesses that don't scale, and scale weights give different wing loadings, etc.) and cannot generally be scaled to match scaling of other effects and dimensions => compromise. The "best" proportions for a a .15-powered stunter are not likely to be the very "best" for a .60-powered one. If a large change in size is for the fun of flying a given design at a new size, I'd probably look at successful stunters of the new (Edit: engine) size and scale to create equal wing areas, as long as both are flapped or both are flapless. That means that your scale factor will be the square root of the ratio of the new area to the old area.
For instance, for the example above, if you have chosen to increase the area from 510 sq in to 586 sq in, then the scale factor will be the square root of (586/510) = square root of 1.149 = 1.072. Tell the copier to make a 107.2% copy or an incrase of 7.2% in linear size.
Note that if your copier cannot go to the tenth of a percent, you're stuck with 584 (with 1.07 scale factor) or 595 sq in (1.08 scale factor), plus or minus their own error. I've had people who could adjust their sizes by the 0.1 % incriments and correct to my pocket-calculator suggestions as well as those whose equipment couldn't do that, or as Keith mentioned, couldn't adjust lenght and height to match. Some really aren't competent either. So, results vary.
I don't know whether much has been said previously here on this topic, but a SSW Forum search will probably find many threads of interest. Searches in both places might prove useful.
SK
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I used different math... 510 x .15 = 76.5... 510 + 76.5 = 586.5 and it seems to work for me .. but I am seeing how 15% of the MC x WS does what you say... you are right... I certainly don't want a 675-710 sq/in plane...
Glad you gave me something to mess with my mind...
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It's probably easiest to understand, if you think of the average chord and the wing span each increasing by 15%, when you scale up by 15%. So your original area is Average Chord x Wing Span, but your new area is (Average chord x 1.15) x (Wing Span x 1.15) = Average Chord x Wing Span x 1.15 x 1.15 = Original Area x 1.152. You can break this down as you did above and make, for instance, the new Average Chord to be (original) Average Chord + Average Chord x .15 = (Average Chord x 1) + (Average Chord x .15) = Average Chord x (1 + .15) = Average Chord x 1.15. Or just think of the new chord as 115% of the old one. 'just one of many ways to think of it, but this is why the area varies as the square of the linear dimension.
SK
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OK the plan is in. enlarger 13 to 15%. That should be shooting for a 58" wing span. not counting wing tips. S?P
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Wing tips ARE very important to the influence for trim. "Vortexes from the tip can cause issues. Low drag high lift." OK I'm not an aero-enginer...I'll let MR. Buck and Mr. Walker......and anyone else talk about tip shape.
Paul and I had a great talk about tip shape back in the time of IC engine's. Impact, Cardinal, ...and the others.
Now today.......I'M just getting re-educated. Been gone so long "is balsa extinct"
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I used different math... 510 x .15 = 76.5... 510 + 76.5 = 586.5 and it seems to work for me .. but I am seeing how 15% of the MC x WS does what you say... you are right... I certainly don't want a 675-710 sq/in plane...
Glad you gave me something to mess with my mind...
If you want to scale it up in terms of area, you compute the ratio of what you want to what you have, and then take the square root of the answer. So in your case, the square root of 1.15 is 1.072. So multiply all the linear dimensions by 1.072 (a 7.2% increase) and you will get what you want in terms of desired area.
Brett
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I will have fun with this project and the calculation's I am using will work for my purposes.
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Greg, a 7% increase in size would be perfect. Brett is giving you good advise and has experience with the engine. I don't understand why you'd bother to ask the question and then ignore the replies from folks that understand what is actually only High School math. H^^ Steve
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I use this spreadsheet to scale plans/designs up or down.
Under the "Original" Column plug in the numbers of the plane/design you want to scale then in the next column put in the scale factor like 1.1 or.95. The spreadsheet will return the dimensions of the scaled airplane. The green line are automatically figured for you and won't need you to input a number. I've included one of my designs as an example. Have fun.
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Greg,
I am glad to see you back among us this year. I hope we get to see you at a few contests
Sounds like you got your question answered and can now move ahead,,
the rest of us are getting something from the extra responses,,,
good thread,,
Scott,, are you going to fly this year?
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That means that your scale factor will be the square root of the ratio of the new area to the old area.
For instance, for the example above, if you have chosen to increase the area from 510 sq in to 586 sq in, then the scale factor will be the square root of (586/510) = square root of 1.149 = 1.072. Tell the copier to make a 107.2% copy or an increase of 7.2% in linear size. SK
If you want to scale it up in terms of area, you compute the ratio of what you want to what you have, and then take the square root of the answer. So in your case, the square root of 1.15 is 1.072. So multiply all the linear dimensions by 1.072 (a 7.2% increase) and you will get what you want in terms of desired area. Brett
Greg, a 7% increase in size would be perfect. Brett is giving you good advise... H^^ Steve
I have to agree. - SK
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Greg, a 7% increase in size would be perfect. Brett is giving you good advise and has experience with the engine. I don't understand why you'd bother to ask the question and then ignore the replies from folks that understand what is actually only High School math. H^^ Steve
I think James it trying to solve a different (but similar) problem than Greg.
Brett
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"you compute the ratio of what you want to what you have, and then take the square root of the answer."
I would have arrived at the right place but taken a longer route... my Dolphin enlargement is a ways off.. right not I have to concentrate on getting 4 planes ready for this season... but dreaming is a mainstay of design... back in my RC days I could design on a napkin drinking coffee and fly the plane the next Sunday... where did all my energy go?
This a gem ... Serge and Brett you guys are great..
Scott are you going to fly this year?
JJ
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MARK...Thank you for the question about flying this year. I've had two surgery's. BOTH where inconvenient. I had a stomach issue and and and ASS ISSUE....LOL. The doctors found cancer in both...........HOWEVER, the stomach issue will be resolved in the next few weeks. The Colon we take some time ....However, it's caught very early and the doctors say It's all good!!!! SO I'm going to help Greg build an Plane.
STEVE....my friend REALLY?????
Brett has given an assume answer. IT'S ALL GOOD. OH Steve you need to build a plane this century.............OHHHHH I did it...........BAD Scott BAD..........
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All I do is decide what I want the wingspan to be, figure out the percentage increase needed to get there, and then have Kinko's copy/print an enlarged set of plans. What model design are you wanting to enlarge?
That works for me and there is no reason not to do it that way. I have done it this way with my Arctic fox and three differnt sizes and all flew the same including my electric fox HB~> HB~> HB~> HB~>
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Build an Impact, paint it to match your JD Falcon, put "JD Falcon" on the left wing. Problem solved. y1 Steve
[/quoteAT least this guy builds planes and you don't! i WISH i COULD AFFORD TO BY MY PLANES LIKE YOU DO R%%%%CLP** CLP** CLP**
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For all the input this post has given to my question. Most of the responsive's were what I expected from the one's that know what they were saying, like the one's that have done it before. I was though not impressed with the response that implied that my math skills were lacking, n1or that I am ignoring the opinions of the great responses that were given. I hope all of us are on this forum to uplift each other in there skill levels. Not to judge another for what there may or may not know. Most of us do what they can when they can in God's given time to do so. I want to thank the one's that are so kind to share there knowledge. Oh for fun, does Spell check count? lol
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Hey, we all types on here, with all levels of talent and knowledge. You will learn if you stay with it long enough to know who to listen to and not listen to. Also learn not to respond to them as they will just keep the pot burning. I guess I am one of those individuals. S?P S?P VD~
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Greg...Spell Check???
Last time I used spwell chque I ask My Mother."MOM...How do you spel feriend".....LOV U ALL 010!
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FYI: The J.D. Falcon Has a 23.5" inbd wing and a 22.5" outbd wing . Add to this the 3.5" tips and the total wing span is 53.5". The kit was developed using John D'Ottavio's metal rib template which was made by a tool and die maker. This assured total accuracy.
I had a .60 size Falcon at the 1st Lawrenceville Nats. The airplane was designed for ST .60. Nearing completion, Windy talked me into going to a pipe. I don't recall which engine I used. For this reason the fuselage was fattened up to create a pipe tunnel. The airplane looked ok but being this was in the earlier days of the pipes, we had a lot of inconsistent runs. We now know that the pipe exit was much too small.
As many remember, the condition at that Nats were terrible. The .60 size Falcon had a foam wing. I hit a pot hole when landing and it was all over. The wing was destroyed. I have a picture of the airplane somewhere, but haven't found it.
Today I would use a much blunter airfoil similar to Bob Hunt's Crossfire.
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Thank you Tom,
I hope you can find the photo . Sure would like to see it. Can you tell me the date of when you built and designed that 60 size Falcon?
Thanks!