My first fixedWing plane
« on: March 16, 2019, 09:36:36 am »
Hello there,

One year ago I started researching about LibrePilot and how to build my own plane (fixedWing).
After watching a lot of videos on YouTube, I decided it's time to start from somewhere.
As majority of fixedWings are made out of different types of Styrofoam, I decided to buy some
extruded Styrofoam(I hope that extruded is the correct name) and to build my own foam cutter.

Downloaded a Wing templates, inside and outside of the Wing. I printed the template on a A4 paper.
By gluing the paper template on a piece of Plywood and cutting the Plywood with a hobby moto-saw,
I was able to make the hard temples for inside and outside of the Wing.


This is the final result.



Below you can see the other parts that I will use for my plane:

 - Camera sender and receiver:


 - 6CH 2.4GHz Receiver:


 - 2 x micro Servo 9g:


 - I don't know how this component is called, these will be glued to the Aileron:


 - Wire for connecting the Servo with the Aileron:


 - GPS module:


 - ESC 30A:

 
 - Motor A2212 / 13T | 1000KV


 - Propeller 10 x 4.5 (I think these are in inch)


 - cc3d board


 - Wood to make the wings stronger
 - Cover Film that will make the plane stronger

Next is to assemble all together and to buy some battery based on TheOtherCliff hints.
Hoping that my researches in the last year were OK, this should fly...  :)

Best Regards,
Alex

PS: I don't know to make the pictures smaller from the forum interface...
PSS: I changed the size from the source, it's better now.
« Last Edit: March 16, 2019, 09:44:58 am by Alex H. »
Best Regards,
Alex H.

Re: My first fixedWing plane
« Reply #1 on: March 16, 2019, 06:06:46 pm »
Quote
I don't know how this component is called, these will be glued to the Aileron
"Control horn" and they are screwed together with a matching plate with the aileron/elevator/rudder (elevon for you) sandwiched in between.  You can certainly add glue if you like.  :)

Quote
PS: I don't know to make the pictures smaller from the forum interface...
PSS: I changed the size from the source, it's better now.
The forum basically only knows icon and full sized.  Be aware that instead of linking to an external picture you can upload the picture and make it part of the post and it will automatically be shown as an icon at the bottom of the post and can even be inserted full sized where you want it in the post.

Ultralight experience will help a lot, but the thing that gets real pilots in trouble when they fly models is the control reversal.  When flying toward you, left is right and right is left.

<bragging but all true>
I have a Phantom ultralight that I haven't flown in years now.  I have a BRS chute.  I used to say that I couldn't remember at least looping (inside) or rolling (snap roll) it or gliding it inverted on the most recent flight.  Yes, the float carb motor will stop if you do it too long or at more than idle speed, but if you are afraid of landing such an easy to fly airplane deadstick from within gliding distance of your runway, you should find another hobby.  (Google some Phantom ultralight loop videos). I've never done any outside loops (I have a pumper carb, but never installed it or an inverted fuel system) but I honestly can't count the number of inside loops I have done.  I can say that one time I did 10 consecutive inside loops while deadstick coming down from something above 5000 feet (say 1800m).  It is a great airplane and I had the rough ground handling kit on it which took ultimate load from (+9.9g, -6g) to (+9.9g, -9.9g).  I keep it to a sane (+2.0g, -1.2g) for my comfort.
</bragging but all true>
Here is a random video (not me) to show what it can do.  And readers, if you want to play like this, the Phantom is the one you want.  Bigger motor is nice but not required, and inverted fuel system if you want inverted.


Some things come to mind:

How much does it weigh?  It needs to stay under 1kg ready to fly and the lighter the better.  Figure a battery will weigh a little less than 200g.

Calculating CG (Center of Gravity) is critical to it flying correctly.  There are formulas for calculating CG of a trapezoid wing.  For a straight wing, the CG should generally be about 25% back from the leading edge.  For a swept untapered wing that must be calculated as the average of 25% back along the whole wing which is 25% back as measured half way to the wing tip.  For a swept and tapered wing (trapezoid) the averaging must also be weighted (adjusted) for the fact that the outer wing is small and doesn't count much.  A wild guess is that your wing should balance about 42% back when measured at the center.

The center ribs have an upturned trailing edge.  Tip ribs do not.  It is common to do the opposite where the trailing edges at the tip are slightly upturned (usually just accomplished with a very slight purposeful warp) as compared to the root.  Turning the tip trailing edges up (called washout) means the root will stall first.  If a tip stalls first then that wing will drop and you have lost control.  Also, that upturn is the equivalent of up elevator when you build your elevons (elevator ailerons), just be aware of that.

Hand launching a flying wing is a bit difficult, especially if you are also the pilot and a beginner.  Something like a Bixler 1 is just so much easier to hand launch.  You have a place to grab it (the fuselage under the wing) and the prop isn't going to cut you since the motor is out of the way.  Bixler 3 has landing gear if you want that, but you will need much much much larger wheels to fly it off of grass.



Powered gliders or other airplanes with lots of dihedral also make good trainers.

Built up wooden wings will usually have some warping that must be removed before flying.  Holding the wing very still and looking at it from behind the center at arm's length and sighting along the flat bottom of the wing and looking left and right, you can see if there is a warp in the wing.  I guess you used heat shrink covering.  Hold it untwisted, reheat and hold 10 seconds till cooled will allow you to unwarp the wing.  I would add "washout" where the trailing edge of each wing tip is turned up the same very small amount.

CC3D and GPS:  CC3D does not do GPS flight modes like RTL/RTB.  It only allows the GCS to plot where it is on a map and only if you have added telemetry.  CC3D does do stabilization, like levelling out when you take your hands off the transmitter.  Also, it looks like that GPS is one of the ones that does not have configuration memory and CC3D does not have the code to load the correct configuration at each power up.  Revo class FC does this automatically.  Also, it may be better to have a GPS that has a compass when you get around to doing GPS flight modes.  GPS with compass is only supported on Revo class FC, not CC3D.  DJI Naza clone GPS with compass costs about $20 on eBay; again only for Revo class FC.

There is no general set of FC settings that will work for all airplanes.  The best procedure has you adjusting the settings, starting with the most basic settings first.  That means flying the airplane without FC stabilization to start with to get warping, trim, linkages, control throw max angles all adjusted correctly before adjusting the FC in Rate mode and finally in Attitude mode.  This means flying it without stabilization, like in the old days before FCs.  :)  I would also skip the FPV camera till you have the plane flying well.  Less weight and less expensive things to break in a crash.  :(

Lastly, a story.  I was a 15 year old who wanted to teach himself how to fly.  It took me a year and many airplanes.  Your airplane can fly, but there are many things that can make it crash that all must be correct before the first flight.  The best thing you can do is to find a local model airplane club and watch for a few days, then ask the best flier if there is someone who can help you with all the things you don't know.  I also recommend that you put that airplane away for later when you know how to fly better because one crash will hurt it badly and 3 crashes (and fixes) would make it heavier and less well shaped and harder yet to fly.  These things cost money, but buying a good EPO (a type of foam) foam trainer airplane (not the shape you like, but the shape you need) will be easier to fly, survive crashes better, and be less painful when crashed.
« Last Edit: March 17, 2019, 12:53:21 am by TheOtherCliff »