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• Simple Wing Strap

  Quinn • 07/16/2021 at 22:19 • 0 comments

  I've most of the time used rubber bands to mount wings to fuselages.  While simple, this has some upsides and downsides.  

  Upsides: 

  • Super simple to make and use
  • Easy release during a crash can reduce damage

  Downsides:

  • Rubber bands can dig into wings
  • Can stretch in high g maneuvers causing loss of control.  Adding more to minimize this exacerbates digging into wings

  For smaller planes I'll definitely still use them, but with a recent plane, Rainbow Quartz which is a version of an ultra stik, I wanted to do something different.  I decided to make a sling out of strong fabric and Velcro.

  The strap is a single layer of fabric with a loop on one end and folded taper on the other.  Sewn on Velcro forms the attachment.  I simple stitched the edge to prevent unraveling of the fabric, but you could also glue the edge, or use an artificial fabric and fuse the edge with a flame or soldering iron.   The length and location of the Velcro is dependent on the wind chord.

  The fuselage requires a pair of dowels to attach the strap.  These are the same as if you are using rubber bands, but they no longer need to stick out into the air stream and can be flush with the fuselage. 

  I inserted the rear dowel through the fuselage and the loop/pocket on the end of the strap.  To attach the wing, it can be set into it's place on the fuselage.  The strap is laid forward over it, under and around the front dowel, then back up to attach by Velcro on top.

  It's important for the strap to run in this direction so that wind during flight doesn't push the Velcro towards opening.

  This requires the fuselage to have an opening at the front of the wing so you can pull the strap down around the dowel and back up.
  

  The pressure holding the wing in place without external forces is minimal, just due to the minor stretch in the fabric weave.  While this prevents digging into and wear and tear on the wing, it does mean that the wing needs to otherwise be mounted in the fuselage so it doesn't twist.  This model has a wing saddle built into the fuselage, which i think you need to plan for if using this method.

• Kiki (Graupner Junior Sport)

  Quinn • 05/06/2021 at 15:05 • 0 comments

  I purchased this rather old glider from a club member for very cheap as a project plane.  As I got it, the nose of her plastic fuselage was cracked, her uncommon shaft size folding prop was broken, though a spare was included.  Also, a spare unused wing set was also included.  Worth it just for the pair of 1.25m balsa wings.  She was also still running on a geared brushed motor and NiMH 7S battery.

  Repairing the nose was awkward, but not too bad.  Awkwardly placed clamps and expoxy did the job.
  

  I put on the spare prop and tried a test flight, which didn't go so well, resulting in a small crash which broke the brittle prop.  I had planned on replacing the power system anyway, so this just pushed me towards that right away.  My suspicion was this was a combination of a barely adequate power system and my not being used to it.

  I swapped in an arguably oversized brushless motor and ESC.  This combination has equal power to weight, which is much more than needed for a glider.  However, it was a very good physical fit, and I'd rather oversized then undersized.  To fit, the motor directly screwed in, I just need to mount the wires so the wouldn't run against the can.  I'm worried about overheating as there is no airflow around the motor, only behind it, but will see when I fly it.  I'm hoping that given normal glider use of low throttle and most of the time no throttle should be ok.  After more use, I'll probably adjust the throttle curve so that full throttle isn't used, or only for takeoff.  Swapping to 2S is another good option.

  Despite the more power, this system, including 3S 2200 lipo, cuts 350g off the weight.  The battery needs to move from under the wing all the way up to the front.  So there wasn't really any purpose in going with a smaller power system as I'd just need to add extra weights.

  To keep the out runner motor can from abrading the wires, I fashioned a plastic clip to hold them against the side wall.

  After a test toss, she lost control and crashed, requiring a bit more glueing.  I thought what was going on was a small gust of wind tipped her, and i couldn't right her with just rudder and dihedral.  While that may have impacted things, a larger factor I think was that with as much weight as she has, she needs higher speed than my toss, and it was more of a stall.  But then the next issue.

  My next go was with no wind, and motor power on.  After a little pitch up, I quickly pushed forward to prevent stall, and she pitched up more.  I instantly realized the elevator was reversed, but in that 1/2sec time window to realize that, it didn't leave enough time to counteract instinct on elevator control.  Worst crash yet, denting one section of the wing, and crushing in an area from the hold down rubber bands when the wing hit, only one tip, twisting it.  Sigh.  Checking control surfaces is one of those things that even when done every time(i did here), you can get in such a habit that is more of an instinct, not actually thinking about each motion, every time.

  I was able to patch her.  Some extra CF strips on the fuselage front, and a patch in the balsa sheeting on the wing.  Next flight out, after triple checking the servo directions, was successful.  Kiki definitely requires quite a strong toss, just barely above level so she can get enough speed.  But she flies delightfully.  She needed a little down elevator mix about 6%, from throttle to balance out lift with throttle.  

  After a couple flights the motor started major vibration.  Seems like previous crashes weakened the firewall such that it would flex, allowing this vibration.  With the somewhat narrow gap between the motor and inside of the fuselage, this caused the motor can to rub against the fuselage inside.  I'll need to add a layer to the firewall to strengthen it and reinstall....

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• Opal (Full custom performance/glider)

  Quinn • 04/26/2021 at 20:41 • 0 comments

  Opal was my first plane that I fullly designed myself, without basing her on any plans.  I had been having a lot of fun with Pearl with the straight wing and wanted to make a higher performance and faster version.

  She was made to support swappable wings, with my initial intent to make a moderate wingspan symmetric airfoil one, and a much longer glider wing.  The fuselage is based on an 11mm carbon fiber tube., with horizontal and vertical stabilizers attached with plastic brackets.  Brackets were made with old gift cards, softened and shaped around the tube using a heat gun.

  The front end a plywood structure was attached to the tube and held the mountings for the Rudder and Elevator servos, both connected with a pull-pull system instead of rigid control rods.  The tube was mounted in a pair of bulkheads, on the plywood structure.

  Balance was intentionally made such that the battery sits exactly middle of the CG, allowing a range of battery sizes without issue.  With a smooth bottom and folding prop, she would hand launch, and belly land, but also have plenty of power with the larger prop and motor than what Pearl has.
  

  In the above picture, you can see the motor in it's aluminum bracket on the right.  This is followed by the ESC, and R/E servos mounted below it.  Those servos are connected to pull-pull wires that go through the CF tube.  Continuing left is a 1300mAh battery, though I usually use a 2200.  Last is the battery voltage telemetry sensor and receiver.  

  Opal was laminated from the beginning, having learned how helpful it is for protection, but also added strength.

  I had a couple good flights on her until one day there was a crunch, the fuselage cover fell off and it was clear something had gone wrong.  I landed her without power, risking damage dragging the inners on the grass without the protection of the cover.  The aluminum motor bracket had warmed enough, pulling heat from the motor, to soften the glue to the point it detached.  This swung around allowing the prop to impact the wing.  As the cover was partly attached on this bracket, it fell off.  As it was simple foam, it wasn't damaged, though needed to go out to get it.

  She wasn't too bad to fix.  I reattached the bracket but this time with epoxy, and doubled with reinforced tape. A piece of tape over the wing dent, and she was restored.

  I made 2 wings for her.  The first is 40" full symmetrical airfoil with 30" carbon fiber 6mm tube as a spar.  Full span ailerons give her fantastic roll rate.  This wing on Opal is great for high performance flight.  I'm happy to perform high-g manoeuvres, and fight at high or low speed.  The symmetrical flat wing provides equal inverted performance and a wide envelope.  Her stall characteristics are pretty good, she'll just slightly tip, but is immediately controllable again.  Glide slope, while not true glider performance, is quite good and can catch some strong thermals.  A sample of this airfoil:  (CF tube goes down the middle, between the foam spacers)

  The second was intended for soaring with a more traditional airfoil and 90" wingspan.  I added flaps to aid in landing as well.  As a spar, I had a pair of CF tubes, joined in the middle with a metal rod to give some dihedral.  First flight out was not very controllable, and that rod bent, folding the wings and resulting in a crash.  The fuselage plywood structure  needed to be replaced, but was otherwise fine.

  I gave up on dihedral and reinforced by directly connecting the two 30" rods, as well as sistering them with a third spanning the middle.  I was able to fly and land this configuration, but it was barely controllable, and the significant bowing to the wing extremely worrying.  I've not flown it again like this as I need to change something.  I'll probably...

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• Sadie(Custom 3D)

  Quinn • 04/26/2021 at 20:34 • 0 comments

  Sadie is a profile style 3D plane that was given to me.  While many RC flying clubs tend to be a bit awkward, nearly entirely made up of older men, they do tend to be friendly, kind and well meaning.  One of the regular's at a local field has been nice to chat with an talk about flying offered up this plane.  It was made by another member of the club, and he'd had it sitting around for awhile, not the sort of flying he typically did.

  It is made of 1/4" foam, with a KF step airfoil.  A single square carbon fiber rod strengthens the wing.  The design is made with colored tape.  As it is a profile style, all the electronics are surface mounted on the outside; the goal is simple and very light, for 3D flying, not speed.  She has massive control surfaces, and while small, the motor produces sufficient thrust to hover.

  It has been fun learning to fly, though a bit more stressful as she is so touchy, and more fragile than my other planes.  Sadie is the first plane I had which was solidly capable of knife edge flight, which I spent some time learning.  I'm still not very good with it, partly because I don't take her out much.  She really wants very low wind, and would be great in a large indoor facility.

• Rose (Flitetest Stortch)

  Quinn • 04/17/2021 at 18:12 • 0 comments

  I wanted to make a larger slow flying, "floaty" plane, and went with the Flitetest Storch.  She was made pretty much to plans, with a couple modifications:
  

  • I added lower guy wires to support the wings when in flight.  This is based on others feedback, and the fact that the wing design I didn't think strong enough to resist folding.  I've not had a problem with this setup.
  • For the motor pod, instead of putting spacers between the fuselage and the swappable motor pod, I just made a custom motor pod that was wider, and would fit directly.

  With this project I reinforced and going forward, all the skewer holes with credit card plastic, which has been a fantastic help in durability and longevity.

  I found that the ailerons are not nearly as much as I like.  If I was remaking it, I would have made them extend inboard more.

  As my first plane that I exclusively took off from the ground (instead of hand toss), this was the first time I found that I really needed to start laminating more of the foam.  Some of the undersides, especially on the horizontal stabilizer and elevator, were soaking up water thrown up from dew on the grass.  It's not been a problem yet, but is wearing them out faster than I would have liked.

  Rose is a lot of fun to fly.  She flies so very slow and gracefully.  She'll take off in 4 feet easily.  The flip side is that with such a thick wing profile, it's a high drag, preventing faster flight.  Likewise, she doesn't handle the wind very well.  With so much lifting, a gust can shoot her up or down, and it can be very slow to make any upwind progress.

  I burned out her motor last fall, and have not gotten to replacing it yet.

• Garnet (Flitetest Mighty Mini SE-5)

  Quinn • 04/17/2021 at 18:02 • 0 comments

  Garnet is a small SE-5 biplane, using the Flitetest Mighty Mini SE-5 plans.  She was again cut simply from DTFB.  While cut with a paper pattern, here is a picture of some of the pieces lined up with the projector for cutting.(demonstration for the projector project)

  She's fully cut out, but not proceeded beyond that.  I might come back to her in the future.

• Lapis (Flitetest Bloody Wonder)

  Quinn • 04/10/2021 at 01:48 • 0 comments

  With Connie going a bit rough, I started with something a little easier.  The Flitetest Bloody Wonder was an easy one, quick to put together.  I think I only made 3 changes to the design.  For the ailerons, I used two servos on the underside of the wing, instead of the single one on the top side with two pushrods.  Second after a number of broken props, I added some landing gear.  And lastly, I made a flap on the topside to more easily take the battery in and out.  It definitely should have had this in the design in the first place.

  In construction:

  Aileron servo changes and landing gear:

  The landing gear was attached via rubber bands only, with the goal of hard landings causing them to buckle instead of breaking off.  This did work quite well, though they buckled probably a bit too easy.  It was a good experiment, though with improved landing skill, i probably won't do so again.  I did add a plastic credit card on the bottom, under the gear wire so it wouldn't dig into the foam.

  At one point I did have a particularly bad crash, crumpling the nose and cracking the middle of the fuselage/wing almost completely in half.   One of the advantages of this style of construction is it is usually pretty easy to fix.  I just straightened and glued the fuselage and nose back together.   Here's a post crash picture:

  Lapis is a ton of fun to fly.  Super nimble, able to turn completely around on a dime, and plenty of power to do vertical takeoffs.  She is quite capable in smaller areas.

  As I usually fly her:

• Connie (Flitetest Sparrow)

  Quinn • 04/05/2021 at 19:17 • 0 comments

  My third plane was Connie, a Flitetest Mighty Mini Sparrow.  I also cut this from plans using DTFB.
  

  This one unfortunately didn't last very long.  It was just too twitchy and too quick for where my limited skill level was at the time.  I fixed her several times, but at the end one really hard crash did in the fuselage.  While I could have remade her, I decided to hold off for when my skills were better.  The wing survived pretty well, so is reusable.  I might make the design or something similar again in the future.

  Original construction completed:

  After the last crash:

  
  

  On other planes where the fuselage has broken(notably Pearl and Lapis), I could just glue it back together.  Here there were just too many bends and folds such that I wasn't able to make it straight again.

• Pearl (Flitetest Simple Soarer)

  Quinn • 04/05/2021 at 19:06 • 0 comments

  Pearl was my second plane, a Flitetest Simple Soarer because I really wanted to explore gliding.  This I cut from scratch using DTFB instead of a kit.  I printed the plans tiled and cut out that way.

  I started out as just a glider for practice, and eventually put on a motor.  I later rebuild a custom motor pod to make it easier to battery in and out, as well as lengthening to remove the nose weight required with the original design.

  Original wing in comparison to Sapphire's wing:

  Original glider setup:

  After awhile flying her as a motor glider, I built a straight wing with ailerons.  Using rudder and wing dihedral to turn didn't come naturally to me, and I much prefer the more active flying with bank and yank.  The straight wing was reinforced with a dowel, and later a second one so I could do more aggressive turns and loops.

  With custom motor pod and straight wing:

  The original polyhedral wing without ailerons was also much harder to fly with any wind, while the straight wing much easier. 

  I started doing more sport and acrobatic flying, often flying Pearl with the straight wing.  Eventually the enjoyment of that style caused me to design Opal as a much more capable version all around.

  Coming in for a landing:

• Sapphire/Ruby (Flitetest Simple Cub)

  Quinn • 04/05/2021 at 18:55 • 0 comments

  I started by making my first plane, Sapphire, with a partner making an identical Ruby.  These are the Flitetest Simple Cub.  We started with their laser cut kit, which was a nice time save and way to start.

  Current state:

  Being my first, I learned on it, at first and a 3 channel.  It also meant I crashed and broke it a lot.  Each time wasn't too bad to fix, usually just glueing it back together.  The only pieces I replaced was the vertical stabilizer and twice the motor pod.  

  After some time I added ailerons as well for 4 channel.  I really wish I'd built it with ailerons in the first place because bank and yank is so much more natural to me. 

  These were great first planes, and good to learn on.  I don't fly Sapphire as much now, but still fun and quite flyable today.

  Construction in progress:

  Later adding ailerons:

  Replacement motor pod (probably the second one):

  At one point I had wheels for Sapphire, but they were lost in one of my tree crashes while I was still learning.

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