One Sheet No-Waste Twin Tail Boom Series.

by dharkless | October 30, 2014 | (11) Posted in Projects

Hello again out there....

This article is about a series of planes I have designed around a single concept.  The concept is using a single 3/16 dowel cut in half to make twin tail booms in a  One-Sheet No-Waste design. My goal was to make a small, light, slow flying plane that could be flown in the local high school gym.  I am not sure that I was successful in reaching that goal because the resulting airplanes though small and light are not very slow. They are pretty fast and nimble instead. 

 

UPDATE 1-13-15: I was contacted by Hillbilly30 who has built  #2 from the second plan below.  He has included a description with photos and a video in an FT Forum posting.  He has more flight time with his build than I do with the entire series.  He made a couple of changes.  He used carbon fiber instead of wooden dowels.  He moved the battery to the top of the wing.  He added 4 1/2 degrees of down thrust to fix balloning at full thrust.

 

Hilbilly30's flight video:    

Note: this is best viewed at full screen.

Thanks Tad

End of update.

 

 

The planes were developed in the order they are numbered.  I am presenting them out of order in this article because #3 ended up being the best overall performer and is the one I will most likely feature in the build article.

This is #3 of the 4 designs I have developed so far:

Top View:

And bottom:

#3 Has a 31" wing span with a straight leading edge and tapered trailing edges.   It uses Wing "A" shown on the plans below.  

The plans are a simple pencil sketch with dimensions drawn at 1" = 20" on an 8 1/2 X 11 sheet:

The major dimensions can just be transferred to a 20" X 30" sheet of dollar tree foam board.  Rather than put all of the details on the full sheet I started by dividing the sheet into the larger rectangles then doing the smaller layout on each piece.  I think it is easier that way since you are always measuring from a corner or edge.Like this:

(This set is the rough cuts from the drawing below for Plane #5 added as an update at the end of the article) 

For plane #4 in the series (below) I decided to make a two channel trainer.  It is made from the same plans as #3 above but uses wing "B".  I  reversed the wing so that the leading edge is tapered and the trailing edge is straight (This could be done as a 4 channel with less dihedral as well.).  It looks like this:

Top: 

And bottom:

For this two channel version I increased the dihedral to 6 degrees (1 1/2" block under each wing tip).  It does not have ailerons but banks very nicely in a rudder-only turn and returns to level flight quickly when the controls are returned to neutral.  It can fly either fast or slow and so I think it will be a good first trainer.  It is probably a little quicker at full throttle than most of the store bought "Trainers" out there but at half throttle I think it would compare favorably to most.

 

Now, backing up a step...

There were two eearlier versions before #3 and #4.

Here are versions #1 (left)  and #2 (right):

These both have 40" wing spans.  

Plane #1 (left)  was my my first  disign in this series, the concept plane.  I started out thinking that the wing would be strong enough if I just scored and bent it similar to whart was done on "Olde Speedster".  The wingwas cut out and the bend lines were scored strongly on the bottom side.  The  camber was made by placing two scraps of foam under the center at the wing root and only one under the tip.  This did not produce as much camber as the Olde Speedster and the wing is longer.  It was evident after assembly that the wing was too flexable and would fold in flight so I added a single layered "spar panel" to the bottom of the wingspanning the two fold lines and glued to the .  That stiffened it considerably but I still got some stress wrinkles on the top of the wing in the first flight.  I added 6 skewers to the bottom to reinforce it.  I have not flown it since the reinforcement but it is considerably less flexable in static testing.  I think it will hold up. If I re-build this one I will use the FT method and fold the leading edge with a spar similar to #2, #3 & #4 but thinner.  That will do away with the need for reinforcing.

Bottom view #1(after reinforcing):

I added two skewers through the pod, one in front and one in back of the bottom "spar panels.  I then added two at the back edges of the spar panels centered on each boom dowel.  Those also pierce the pod for additional stability.  One was also added to each of the leading edges (also piercing the pod).  

The good news is that it is very fast and the ailerons are very responsive.  It will roll sharply almost at the top of a vertical stall.  This is the best high speed performer of the group.  Stall speed and landing speed are higher due to the thinner wing however.  

I still have to add the hatch cover to this one.

 

Plane #2 bottom:

 

Planes #1 and #2 were built from another plan:

Plane #2 was built with a thicker wing section.  It uses the FT wing assembly method of attaching the bottom panel to the leading edge of the top panel, cutting the 45 degree back-cuts and folding.  It has two spars on each wing creating a boxed spar.  This is very much stiffer than #1 was and did not need any reinforcement. 

The tails on my prototype #1 and #2  were made from separate pieces instead of one piece folded.  This allowed the vertical stabilizers to step back and the rudders are behind the trailing edge of the elevator.  I think I like that appearance better but the one-piece version is stronger.  The tail surfaces are also larger on these two.  I plan to make another #1 with the FT folded wing and the one piece tail to see how that works out.  I think both changes will be fine. I am showing the one piece folded design in the plan above and will probably us it on all future versions..

Both #1 and #2 have straight leading edges and tapered trailing edges (WIng"A")  but either could be built just as well with tapered leading edges and straight trailing edges (WIng "B") for a differednt look.  

 

Miscellaneous notes:

The ailerons are larger on #1 than on #2 and it is also more responsive.  The plan shows the larger ailerons. Less experienced pilots may need smaller throws or higher exponential for less touchy performance.

The landing skids on all four versions are similar.  They are for landing only and prevent ground scuffing.  Plane #2 was the first I did the skids on and you will notice that the main gear attachment is well back on the wing.  When I did #3 and #4 I moved it forward.  On maiden flights #2 was the only one that nosed over on landing so I am going to use the more forward position for all 4 in the future.

You will notice a short piece of dowel and plastic reinforcements on the left hand wing tip of each version.  These are for hand launching.  You just grip the wing tip loosely between your index and ring fingers and let it hang at your side (pivoting back).  Give it about 2/3 throttle and swing discus style straight ahead (not up as you might expect) and you are flying.  You do not need to throw hard.  The motor will do the work. 

For all four versions I used additional scraps to make some items such as the nose and hatch covers, spars and the motor mounts. 

The longish noses are needed for balance. The batteries are either 1000 or 1250 and are positioned right up at the nose.  Plane #1 actually has a 1250 and still needs $1.50 in quarters at the nose to balance.  I will try a 1500 instead for the next flight.

One added value feature:

These things stack for easy transport...

 

NOTE:  Look for the construction article within a week or so.  

 

UPDATE (11-04-14):

I have made version #5.  It is similar to #1 but has the stronger FT style folded wing and tapered leading edges. It also uses the folded one piece tail.  It looks like this:  

This picture shows the landing skids on the ground as they would be after landing.  

 

 

 

Equipment:

Servos: (2) or (4) 9gram

ESC: 20A - 30A

Motor: Hobby King Donkey ST2204 1550 kv; Turnigy 2822/14 1450 kv

Motor Lead Extensions: Make (3) to fit 3" to 4"

 

Supplies:

Dollar Tree Foam Board: (1) sheet plus a few scraps

3/16 Dowel: (1) pc 36" plus (1) pc 1 1/4"

Flag Wire: (4-5) pc 21"

Hot Glue & Gun

Bamboo Skewers: (2) pc 3"

Packing Tape

Velcro

Used gift cards or flexible cutting board.

 

 

COMMENTS

eagle4 on November 2, 2014
great looking planes mate. i really love the zero waste approach you're going for. Although this article is a bit messy, as in it feels like it jumps all over the place. It doesnt make logical sence to follow it along as you start with number 3 from 4 then go back to 1 and 2. I think each of these planes deserves its own article. then perhaps an article that links them all together where you compair the flight charactistics.
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dharkless on November 3, 2014
Hi Eagle4,
Thanks for the kind comments and the reader feed-back.
I intentionally placed the models out of numerical order.I started with #3 because I planned to feature it in the build article. I thought I made that clear in how I structured the article but I apologize if the result seemed scattered.
I appreciate your comment that each plane warrants a separate article but I think the construction is so similar that separate build articles would be redundant. The only real difference is the wing shape and I think that can be dealt with adequately either in the same article or in a follow-up. It is true that the wing shape makes all the difference in the performance and that is the advantage of this platform. You can pretty much make it into whatever you want. I will probably do a build article featuring one version and a second offering several variations on the theme.
Again, I apologize if anything was left unclear. My brain is a bit scattered and I am afraid my writing follows...
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dharkless on November 5, 2014
Thanks for the kind comments!
I am working on the videos. I tried today but it was too windy and I ran out of room on my camera.
I have made one short flight on each #1 through #4 earlier and they all fly very well. I was not even going to try #1 because of the thinner airfoil but it is actually the fastest and most aerobatic. I only did about 5 to 10 minutes each but I did not perceive any flutter. No bad stalls either. These were the first I tried the wing tip launching method and that works great. The motors really pull them out of your hand. You just swing with the pull of the motor and release level and off they go. The one inch dowel section is just right for gripping and the 1 1/8"square of cutting board reinforces it well.
The pusher configuration helps with elevator authority. I did one dead stick and it was a little mushy.
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Holski77 on November 4, 2014
Beautiful build, I wish you would post videos these things look they would be a delight in the air.

Do you have any flutter problems with the tail booms? I have always had trouble when using a dowel empenage because of flutter.
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ohitstarik on December 1, 2014
I really want to build this, but the plans are really confusing. Lets see what i can do with it though.
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dharkless on December 1, 2014
Thanks for the comment. The plans may seem confusing because there are two different plans shown and you can make at least two different versions from either plan. This article was intended as an introduction to the concept and not as a construction article. I have drafted a construction article that takes you through the construction of version #5, the last one shown but I have not published it yet because I was hoping to have flight videos to include. The weather here has turned so that I have not been able to get the flight videos. I also was not satisfied with the quality of some of my photos. Since you are trying to build I will take a look at that draft and probably publish it without the flight videos.
There are 5 different versions shown. Had you settled on one?
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ohitstarik on December 1, 2014
Oh no i just looked through it a bit more and i understood how to build it.

I'm just used to being, like, hand fed on information on how to build things. The wing part was what confused me, but i got it working. Right now i'm drawing things on the foamboard and i'm about to cut the parts out. I'm building #3.

still rated 5 tho

Looking through all your articles, looks like there are a buch of things i can build from you. Thanks!
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dharkless on December 1, 2014
As long as you are following the fact that I am showing two different wings on each plan you should be OK. If you have any trouble e-mail me at dhark69@gmail.com. I will give you my phone number and can talk you through any vague spots.
The dihedral angle will be made automatically by the wing folds. When you put the wing halves together you will have about 3 degrees without making any cuts.
The wing blanks are the same for 3 and 4. Just make two "A" wings instead of "A" and "B".
Another tricky point is fitting the fuselage to the wing. I would suggest making a template from scrap.
You might take a look at the 80" wing article. Most of the wing details are similar.
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ohitstarik on December 1, 2014
Wow! Umm.. Thanks for offering to help. I'm flattered honestly. I saw the note at the margin of the paper that said make 2 of the wings a or b, and realized that there was an a and b on the paper. I have the wings cut out now. I think i have this project now. I will be building more of your projects later on (especially the landing gear), and if i have trouble i will contact you.

Thank you!
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dharkless on December 2, 2014
one more detail that is not noted...
The 36" dowel is cut in half and then the longer one is trimmed exactly to match the shorter one. Hold them even with the back of the tail and lap 2" from the leading edge of the wing. Lay our carefully so all is parallel to the wing joint so the tail is straight. Glue to tail first with the tail standing on end on one of the vertical stabs and the dowel against the board.. Any dowel curve should go toward center (up). When you glue to the wing hold to layout marks and all should be good.
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dharkless on December 14, 2014
The #3 build article is published. How are you making out?
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ohitstarik on December 16, 2014
ehhhh not that great. I was messing with the thrust angle to get it to work properly and found out that the CF tube i was using to hold the back was cracked, so i took that out and didnt really touch the plane untill you posted the article again. I guess ill start from scratch since i really messed up while building the wing. Ill keep the fuselage though since i modded that to hold up my fpv camera and stuff.
Ill post a video into a cool category with onboard video once im finished. Thanks :)
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dharkless on December 16, 2014
So far my thrust angles have all been straight. I am not sure that is the best answer.
In response to your question I looked around and found an answer here on FliteTest. It is "Motor angles for pusher planes" by franck. I am adding the related article to all of my pusher articles. There are other sources of info out on the net but this one considers several components and helps explain why my straight configuration works.
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ohitstarik on December 16, 2014
Yeah i've read through that article before. I've tried straight and its just pitching mine down. Maybe i should angle it down on the horizontal stabilizer? Who knows. I'm using a 2200 mAh battery and a gopro-esque camera up in the front, so the extra added weight might pull the center of mass down even further.

But yeah straight never worked for me, even after trying it. Even this Icon A5 i have angles the motor down, and theres no horizontal stabilizer to hit in the way of the airflow. Just some sort of magic i need to research more i guess.
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dharkless on December 17, 2014
My 1250 was clear up in the nose with ESC and receiver behind. I tried 1500 and was too heavy. Camera should be at the CG unless it is VERY light.
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dharkless on December 17, 2014
Were you able to get the CG at the proper point with all that weight up front? I used 1250 and no camera, The CG should be 2 3/8 " back from the leading edge.
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dharkless on December 1, 2014
The wings fly very well, especially the 80" one. I have about 20 flights on the prototype. I made a couple of changes on landing gear but otherwise as shown in the article.

I am also working on 1/2 sheet, twin tail boom and wing designs for indoors. Testing this week.
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ohitstarik on December 1, 2014
ooo! That sounds exciting! I really want to go back to smaller scales. Ill keep updated.
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dharkless on December 3, 2014
I am now building a second #3 and taking pictures for a build article. I hope to have it up by this week-end. I would love to see some pictures of your build. You can e-mail them to dhark69@gmail.com.
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Yogenh on December 30, 2014
This dose look like a real good starter plane.
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dharkless on December 30, 2014
Look at #4 above. The wings are swept back using wing "B" from the first plan instead of wing "A" that was used on #3. You also have to increase dihedral to 6 degrees by putting 1 1/2" under both wing tips while joining and trimming the center of both wings till they come together front to back Then just eliminate the ailerons and plug rudder into radio 2.
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dharkless on December 30, 2014
You can build from the 3# build article and just make he few changes.
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Yogenh on December 30, 2014
Thanks will talk to others and get them going.
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dharkless on December 30, 2014
Good luck. Send pictures: dhark69@gmail.com
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One Sheet No-Waste Twin Tail Boom Series.