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Old Jan 11, 2013, 09:10 PM
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United States, CA, Madera
Joined Sep 2012
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giant scale pt-17 plans ?

I am thinking about building a giant scale pt-17. any plan reccomendations? I
was thinking of increasing the scale of guillow's plan that I have seems to be a pretty good design with semi symetrical airfoil. any thoughts on this?

thanks,Robert
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Old Jan 12, 2013, 12:14 AM
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I suppose that is a scale airfoil shown on Guillow's plan? If so, it's gotta be a first for them. IIRC they re rather famous for putting some made up flat bottomed affair on most of their designs.

I know a fellow who took Guillow's P-40 kit plan and blew it up to 1/5 scale for a static display. He checked it against actual parts/assembly drawings I supplied him and felt it was quite good. He did add scale airfoils on all surfaces etc, but otherwise it's all Guillows. It's now on display at a USAF base in TEXAS.

So I guess you could do worse, scale wise.
http://richard.ferriere.free.fr/3vue...npt17_1_3v.jpg
and
http://richard.ferriere.free.fr/3vue...npt17_2_3v.jpg

Regarding the scale semi-symetrical airfoil: On the real aircraft this proved to be a bit too sedate for serious aerobatics. It supposedly has a penchant for not stalling cleanly/consistently, causing some interesting recovery situations. Fix was to add a trangluar "stall strip" (right triangle sectioned wood piece approx 2" across the diagonal with point of 90deg corner headed directly forward) to wing LE. Length of piece and or pieces depending on the total desired effect (as I understand it this did not delay the stall but insured that when it occured it was cleaner- more stall strip made it more abrupt). This stall strip could be added full length to each upper and lower panel, but various other combinations have been observed. Last Stearman I saw with i t had short pieces, approx 6' long on inboard end of all panels. I've also seen it full panel uppers only. I've never seen it added to upper center section, nor seen it extend around the wing tip. A wide fabric pinked tape (6"?) usually covers the whole affair and helps fix the strip in place.

Historically, I'm not sure when the stall strip was added. Was it developed before, during, or post WWII?? I do know that most current restorations seem to leave it off.

I once observed a 1/6 scale Pt-17 with scale airfoil and no stall strip attempt a snap roll. Model was suddenly ALL over the sky, first climbing then bunting in a deminishing series rapid ocilations, recovery was over the crowd and over 60-70 ft of alitiude lost almost instantly. I suspected the model experienced a similar problem as the real aircraft, as otherwise, the model flew like it was on rails.
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Old Jan 12, 2013, 08:02 AM
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Nick Ziroli has plans for two sizes of giant scale PT-17s. http://www.ziroliplans.com/zirolipla..._frameset.html
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Old Jan 12, 2013, 10:59 AM
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United States, MD, Elkton
Joined Oct 2011
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Quote:
Originally Posted by TomCrump View Post
Nick Ziroli has plans for two sizes of giant scale PT-17s. http://www.ziroliplans.com/zirolipla..._frameset.html
Nick Designs models that fly well, and are pretty easy to build.Kit cutters have them in various stages of completion IE: short or full kits,with 'glass parts available.Robart makes articulated (functional?)gear for both sizes...

His design has perfect stall characteristics-they can be '3-pointed' easily.
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Old Jan 12, 2013, 09:48 PM
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United States, TX, Leander
Joined Sep 2003
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I have the ziroli 77" stearman. Flys very well and predictable. They have an 87"ws version also. Balsa USA has another at 1/3 scale, but pretty pricy. I've seen that one fly with an RCS radial on it. Sweet sounding engine. There is a build thread on rcsb for the ziroli 77".
Edwin
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Old Jan 14, 2013, 09:07 AM
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United States, CA, Madera
Joined Sep 2012
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thanks for the information, I may order the the ziroli plans , unless someone has a set they are done with and would like to make them available. the BalsaUsa kit looks awesome and includes nearly everything to make a very detailed model. yes its quite expensive. I see several plans available on ebay but there isnt much information in the descriptions.Does anyone have any experience with the pt-17 plans currently available on Ebay?
I am most intrigued by Packardpursuit's comments and I am actually leaning toward learning more about aircraft design, drawing my own plans and getting involved in creating or collaborating on some large scale open source options; plans that are free to use and improve. I am getting close to retirement and thought it would be nice to actually use some of the engineering skills I learned in college. It would be great if the g code for laser cutting model plans were more available too. I know a lot of people make their living selling kits and plans. I am not looking to trample over their patents and copyrights, but this hobby should be more affordable than it is.

anyway back to the pt-17 , I am going to scan the guillow's airfoil and compare it to a scale airfoil to see how close it is. yes most of the guillows models have flat bottoms , I assume this was because they were designed primarily for rubber power and or freeflight, dont think the were ever mean't to be flown inverted. I thought as micro rc gear became more common , guillows would redesign some of their kits toward this market.
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Old Jan 16, 2013, 10:35 PM
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United States, AR, Alexander
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Jack Strickland in Oklahoma Great flyer and very strong design !!
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Old Jan 16, 2013, 10:37 PM
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United States, AR, Alexander
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Flair Kits also!!
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Old Jan 16, 2013, 10:37 PM
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United States, AR, Alexander
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Amr ???
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Last edited by daleflysrcp47; Jan 16, 2013 at 10:41 PM. Reason: capital letters
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