Sentry R3 - Design of a Foamboard Scratchbuild

by Jamblor | July 28, 2013 | (14) Posted in Projects

Hi Everyone,

This is my first (sucessful) scratchbuild. I call it the Sentry R3. The video below will introduce the plane and the major components and will provide you with an idea of the flight characteristics both onboard and from the ground. Below the video I will post the specifications of the plane and several pictures. I really enjoy this plane as it zips along when the winds are calm and if there is some wind, well I send it straight up and have fun gliding it back down.

I hope you enjoy this plane and I'd love to see people build it for themselves to try out, or modify to make it better! And if you do build one please share the photos or videos.

Thanks and enjoy!

 

Specifications:

  • Dollar Tree Foamboard and 1/2" Pink Insulation Foam
  • -1m (40") Wingspan with a KFM2 airfoil
  • CG ~ 180mm back from the nose.
  • AUW: 360g (12.9oz)
  • Turnigy D2822-14 1450kv
  • APC 7x4 prop.
  • 20A ESC
  • 1000mAh or 1300mAh lipo
  • 2 x 9g servos
  • Elevon programming.

 

Notice the air scoop on the electronics pod. With this design to streamline the electronics, I really needed to direct some aircooling over the esc. Also note that the two tail fins are angled at about 70-80 degrees.

Simple motor mount, thrust line parallel with the foamboard. Also note the carbon fiber spar running along the KF step of the wings.

The underside with two rails to provide strength and hold the servos.

Note the dual control linkages for elevon control on both ailerons and elevators. I tried this design without the ailerons and it has a very hard time banking.

The inside of the electroncs pod.

And finally the plans. These were done in a cad program and then printed full size to pdf. I tested printing them with acrobats tile feater and it printed to scale so hopefully it will work for everyone. If not please let me know so I can fix the plans.

Simply print out the pdf, tape them together and cut out the shapes. Trace onto the foamboard and cut away. The first file is the full plans and the following two are how I cut the shapes out of regular sized dollar store foamboard. (These plans are more cutting plans)

Sentry R3 - Full Size Plans

Sentry R3 - 20x30 Cutting Plans - 1

Sentry R3 - 20x30 Cutting Plans - 2

Please leave comments and rate.

Thanks!

 

- Find this article & others like it at www.FliteTest.com -

COMMENTS

Da99er on August 2, 2013
Awesome design. I've been tossing around ideas in my head trying to accomplish some of the same design goals you have here. I hadn't thought of going horizontal with the pink foam fuse thought, great idea. Have you thought about trying one with a 30" wingspan? I'd like to be able to cut the wing from one piece of foamboard.
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Jamblor on August 8, 2013
Thanks for the comments! I haven't thought about going smaller as I'm trying to design something that has room for a camera or extra batteries if needed. However, I don't see why a 30" wingspan wouldn't work. This plane as it's set up has a min. cruise speed on a calm day at just over 1/3 throttle. So with a shorter wingspan the min. cruise speed might need half throttle or so.
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Auxiliarypower on August 2, 2013
Slap a Keychain cam on that bad boy and lets see some flight footage...

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Jamblor on August 8, 2013
I did include some flight footage in the above video, I'm just waiting for a nice calm day to take some more. Thanks!
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joann69 on August 2, 2013
A wonderful design Jamblor. I do have a question about the power pod on the top of the fuse. Where do I find the plans for the power pod? Also do you have the instructions that you can post for us so that we as foam airplane builders can build you design. I have built several of the FliteTest swappables and would really like you build your design.
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Jamblor on August 8, 2013
Thanks for the comments. I haven't actually drawn up plans for the power pod as this was a last minute addition to streamline the plane for gliding. The plane will perform fine with the electronics just simply velcroed on top. I did post pdf plans above, including a cutting plan that needs 2 sheets of 20"x30" foam board. If those plans plus the above pictures aren't clear enough I can write up some instructions when I have some more time.
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tramsgar on August 3, 2013
Looking good, thanks for sharing!
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Mr Bean on August 3, 2013
Nice design and this plane flies great. Do you recommend this plane for a beginner???
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Jamblor on August 8, 2013
I would recommend this as maybe a second or third plane only because it doesn't have any dihedral and does not level itself after a turn like a trainer. Also on a windy day it can be quite a handful to control for a beginner.
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3DMad5 on August 4, 2013
That's a really nice looking plane

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enivid on August 4, 2013
kickass design!
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sailorJohn on August 5, 2013
Cool plane
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cattail on August 19, 2013
I know it's me.... but.... I am having trouble understanding the plans you have at the end of your pictures. On the two "cutting plans" pages..... these are not the standard "print and paste" kind of plans are they? I usually download tiled plans and then tape them together and then paste these onto the foamboard.... Like I say... I am confused as to how to use your plans.
The full size page has no indications as to what to measure.

Thank you in advance for your help. This wing is really something that is "buildable"!
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Jamblor on August 19, 2013
Hello, Thanks for taking an interest in my design!
Both plans (the full and cutting) are meant to be printed out with the 'tile' feature in acrobat reader. The full size plans are the standard print, cut-out, and trace. However I included the cutting plans as well as this is how I build the plane from 2 sheets of foamboard. The cutting plans are also full size and should print to scale when you tile and print them. The rectangular outline in the plans should be equal to the size of a 20"x30" piece of foamboard. If you are having more troubles please let me know!
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rounce on August 29, 2013
I learned a few things from this..... I can tile pdf plans using acrobat reader and linking elevator and ailerons physically and using an elevon setup . Plus a nice set of plans for a next build. Well done!
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Canadian on March 7, 2014
Really like the plane thanks for sharing it and the plans building mine tomorrow
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Jamblor on June 13, 2014
Thanks for the comments everyone. If you've built/flown it feel free to post or send me a picture/video. I will likely be working on another simple foam board design in the coming months and will post plans and a video as well.
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Sentry R3 - Design of a Foamboard Scratchbuild