Easy Foamboard True Airfoil Wing Construction - Page 16 - RC Groups
Thread Tools
Oct 04, 2011, 09:52 AM
Registered User
Whoopz, what makes up the fuselage on this plane? Can you show the underside? Also curious about your servo placements.
Sign up now
to remove ads between posts
Oct 04, 2011, 10:05 AM
Ed @ Experimental Airlines
ExperimentalAir's Avatar
Originally Posted by Whoopz

When you are trying to find the starting CG of a plane are the ailerons included in the wings chord? The wing has a 7" chord and the ailerons are 2".
While it's technically true the MAC should include the control surfaces of they contribute any aerodynamic force (ie: lift), and thus be factored into the CG calculation, there are a few caveats.

From my experience, if you decide to include the control surfaces in the calculation, still err on the side of going a little nose heavier in your CG choice for maiden flight. If you leave the ailerons out of the math that will tend to slide your Center of Lift and Aerodynamic Center forward, resulting in your calculated CG being forward too - which is a safety measure.

More esoteric considerations below, if interested:

As someone who likes to keep my designs simple I often try to leave out a rudder. This often necessitates tweaking a little differential aileron in various ways to counter adverse yaw. One easy way is to reflex the ailerons up just a little so they are "blanked" by the airfoil, neither adding nor defeating lift in the neutral position. But it ensures the upgoing aileron hits active airflow slightly before, and at a greater angle, than the downgoing aileron. So the inside wing has decreased lift AND increased drag, thus yawing it into the turn - what the rudder would ordinarily do. So with this, my ailerons exert no lift when neutral and a negative net lift input with pitch up tendency when active. That's why I, personally, for my builds, don't "count" the ailerons for CG determination.

With transmitter mixed differential - same consideration.

With mechanical differential at the linkages - same consideration. With your single-servo aileron setup you could easily arrange the pushrods to originate from closer to the servo axis and splay out to the control horns to work in some differential aileron. If your ailerons are overactive due to the long servo arm length, this would tame that problem too.

Short wingspan makes it not so necessary but I'll always take a freebie advantage when it's simple to build in.

Anyway, any builder will tell you to go a little nose heavy if anything. I'm just thinking out loud here.

It's a beaut! Get 'er flying!
Oct 04, 2011, 10:12 AM
Ed @ Experimental Airlines
ExperimentalAir's Avatar
Originally Posted by Whoopz
I know the original design of the wing calls for the ailerons to basically be built in as you make the wing. However, one thing I noticed is that with longer ailerons they get really floppy. One thing I found that works well is to go ahead and just cut the ailerons completely off and use Elmer's foam board for those. That's with the paper still on.
That's true, ailerons will twist, especially if narrower than 1 1/2" and even more so if the control horn is somewhere other than the center of the control surface, span-wise that is. In-wing servo helps that. Tape on top and bottom helps a little too.

Good call on leaving paper on both sides though. You could get fancy with the construction process to selectively leave the paper there, or just cut 'em off and build from virgin foamboard as you suggest.
Oct 04, 2011, 10:36 PM
Registered User

The fuse is made up of a piece of coroplast. I bought a sheet of it from Lowes.

It is basically just folded in to a box. What I did was make the fold and run a bead of hot clue down the fold line and let it cool. Holds the fold really well after that. Has be HOT glue though. Didn't work out to well on the cool setting on my glue gun. One servo is mounted in the top center of the wing.

The fuse itself is 14" long. I chose 14" because that is twice the width of my wing minus ailerons. Each side is 1 3/4". I basically did the size based on my battery.

This is only a aileron/elevator setup. I put the elevator servo on the rear of the fuse. Not too happy with the placement. I think I would have been better off put the servo out on the tail but was concerned about the weight. If it doesn't work out well I plan on moving it.

I zip tied the fuse and the tail to the arrow shafts. I left the entire bottom of the fuse hinged makes it really easy to get in there and move stuff around. I just use three rubber bands front/middle/rear to hold the fuse closed. Will let you know how it holds up tomorrow.

I put a dowel in from of the wing to mount it but tied the rubber bands to each tail boom.

I left things kind of rough simply because I will make another versus without all of the bugs.

Just wanted something simple that could be quickly fixed or thrown away without much fuss.

I didn't do any math for the tail. Made it basically half the length of the wing and the vertical stabs are basically the same size and made of coroplast.

If you have any more questions let me know. Hope to fly it tomorrow. Will let everybody know how it went.
Oct 05, 2011, 05:41 AM
Registered User
Has anybody tried using Coroplast as the spar material in these wings?? It seems like it would add a lot of stiffness/toughness for just a bit more weight.
Oct 05, 2011, 08:50 AM
Registered User
I've thought about it. Was going to do it on the next wing for the little plane I just made if I broke the current wing.

The sheets of coroplast come in a size differant than the foam board so seams wouldn't line up either.
Oct 05, 2011, 11:53 PM
Registered User
Maiden flight didn't go so well. Nooby pilot error is to blame. Forgot to tone down the controls for the first flight. The motor shaft got bent but the rest of the plane is ready to go. Already have a new motor ready to go in and redid the motor mount.

I think people are going to be pleasently surprised by this little guy.

The wing did great. Used to having to take off at full throttle. At half throttle this thing will glide right out of your hand and start flying.

Will post pics of the modifications and fly it again tomorrow :-D

btw this was my 6th Armin wing. Still have two other planes in the works.
Oct 06, 2011, 12:29 PM
Registered User
Any flight you walk away from is a good one! ;-)

Missing some good videos here guys! :-)

I'm hoping to get mine up this weekend. 90" span (triple Armin Wing with wing boxes, with 8 deg dihedral), 45 inch fuse (graphite golf shaft). Park 480 w/ 12x7 prop. Giddy Up!

And yes, I'll be video taping the maiden for posting.
Oct 06, 2011, 04:34 PM
Registered User
I know I know. I've been looking at cameras. Been looking for ones that I can use for FPV if I when I get that far with it. The Sony Bloggie looks promising. And has already been proven for FPV.
Oct 06, 2011, 04:40 PM
Registered User
stonerscolony's Avatar
Little update on my own FPV build using the Armin wing technique as seen in my earlier posts I made a 2 piece wing with ply enforced center section for mounting electronics inside. Is it possible to Solar-film depron as I asked myself in other thread here?? The answer is YES, I used a regular iron and started with the lowest heat. There are areas of wrinkle I managed to get flat but overall I love the result.

I made cut outs on the wings roughly where the lights are inside (its my tattoo and has meaning too me) now the film is over they should light up nicely.
Oct 06, 2011, 05:29 PM
Watt Waster
Tsavah's Avatar

Camera on the Hat and on ...

Originally Posted by Whoopz
... I've been looking at cameras. Been looking for ones that I can use for FPV ... The Sony Bloggie looks promising. And has already been proven for FPV.
I suppose a person can go expensive for FPV and other uses, but why? There are a bunch of spy camera options for around $10 and if you want to go a bit more, there are the slightly larger video cameras, like the one made by Turnigy. If the color balance or some other detail isn't good enough, you can use scrap plastic film, or sun glass lenses to adjust the results. The bottom line is cheap is a good thing, especially if the camera might get damaged. I have a pair of sunglasses I glued a little foam shelf to, covered in epoxy and very thin, lightweight fiber glass. I used double sided tape to mount the little $10 spy camera, called a DVR, to it. I used the double sided tape so I could remove it later if needed and align it better. I also glued a short piece of under-the-sink plastic plumbing pipe, shorten to around 2 1/2", to one eye lense of the sunglasses.

As long as I use that eye to keep the model inside the circle, the DVR spy camera will always "see" the flying RC model. Otherwise the model might fly off one edge of the video frame, or the other. It is amazing how well I can track the model in flight using the dead-simple short tube sight/site. I didn't want to get fancy, but I did want to make it easier to keep the model within the video frame and end up with a smooth tracking result. Works better than I thought it would. Since I was recycling an old pair of sunglasses, and the plumbing pipe only cost around $2, I suppose with the $10 DVR spy camera I have less than $20 invested. Maybe one of these days I will decide to get a bit more spendy, but I don't think that will be this year or next. I just don't see the need to spend more.
Last edited by Tsavah; Oct 06, 2011 at 05:32 PM. Reason: spelling ...
Oct 06, 2011, 05:44 PM
Registered User
Maiden flight of "Strato" went great. Pheww! those first few minutes were a heart pounder. This thing changes direction FAST. I'm going to be moving the rates down. I didn't notice any control issues from my overly long aileron control rods however they do give a really cool side effect - the plane sounds like a train whistle when you're in a dive! I'll probably eventually move the servos to the wing, but for now I'm going to leave things as they are - I'm lazy, and I like the whistle The de-papered symmetrical Armin wing seems to perform great with no bad characteristics that I could find, but then I'm hardly a qualified test-pilot.
Oct 06, 2011, 05:56 PM
Build straight - Fly twisty
Whiskers's Avatar
See? I was right
In post 220 I said, "That will fly really nicely, Hubec."
Well done you.
Oct 07, 2011, 02:28 AM
Registered User
Originally Posted by Tsavah
I suppose a person can go expensive for FPV and other uses, but why?
Thats an easy question to answer. My expectations are differant than yours. I've been looking for awhile now and this particular camera meets all of the requirements I have at a price point I can afford. If you want to know more about the choice a made and my thinking behind it send me a private message. I don't want to derail the purpose of this thread to much. For fear that Ed might drop a six pack on my head.

The thing is I now I can get live footage of my mishaps for your viewing pleasure.
Oct 07, 2011, 07:09 AM
Registered User
east6008's Avatar
This bending thing is a revelation, I fiddled around with a piece and
also came to the conclusion you could make a nice fuselage with
the right angle bends---next thing is somebody to figure out compound curves

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Build Log SEW-SLO 30" Foamboard Wing Atx_Heli Foamies (Scratchbuilt) 73 Mar 27, 2016 03:15 AM
Build Log SEW-SLO 30" Foamboard Wing Atx_Heli Flying Wings 0 May 19, 2011 10:47 PM
Discussion airfoil and wing construction foxjazz Dynamic Soaring 0 Oct 02, 2008 02:04 AM
Question True Airfoil Foamie Wing Structure - Silverslick Foamies (Scratchbuilt) 4 Apr 05, 2008 10:51 AM
Lightweight full-airfoil Depron wing construction? mike98624 The Builders Workshop 27 Apr 22, 2005 01:07 PM