1m Beech Staggerwing D17S

[aelflyer]

Time to decorate (custom decals)!

The time has come to decorate this plane. I'm afraid of adding even more weight to this plane, so I looked around for pictures of white Staggerwings. I settled on NC79091's paint scheme. Here's the reference image:



To create the larger window/striping/lettering decals:

1. Fadi created the decals in digital form
2. I printed the (black) decal shapes on normal printer paper and cut them out (roughly, with extra border)
3. I sprayed the back of the paper with the same removable glue I use for attaching plane patterns on foamboard, then glued the decal patterns to self-adhesive colored vinyl
4. Cut out the vinyl stickers with a razer blade, align to pencil parks on plane, and stick the vinyl on.

Here are pictures of putting the wing numbers/letters on. After cutting out the individual stickers, I taped the resulting template onto the wing with temporary tape. The black letters are red vinyl with the black printed pattern pieces still glued to them, whereas the red letters are the final appearance with the pattern pieces removed.


For the smaller markings (flags and tail letters), I printed them out in color, cut them out, and glued the paper directly to the plane with permanent spray adhesive.

Here's the final result. The American and Tunisian flags on the nose are in honor of this plane's Tunisian/American co-design:

 

[aelflyer]

Final weight

Decals are on. CG is set to ~2.5" back from LE of lower wing (balanced upside down on lower wing). Prop is on. Transmitter and ESC are programmed. Control surface throws are checked. Battery strap and velcro are in. Thrust angle is set down and right. I can't think of anything else to do.

I started with a HobbyKing 30A ESC and measured a max draw of 24A at full throttle with the 10x4.5 prop on the bench. However, after multiple sessions of listening to long serenades of confusing beeps, I cannot for the life of me figure out how to program it. I'm therefore switching to a Flycolor 40A ESC I have sitting around, which has the added benefit of a 4A BEC (rather than 3A)---a nice bit of extra amperage to run all the servos. Moving to this ESC is a 10g weight penalty, but I barely notice the difference in CG. The same prop/motor now pulls 28.6A (330 W) at full throttle on the bench. I am hoping that means it is generating proportionally more thrust, but I have no way to measure it. It draws 16A at 60% throttle. Estimating flight times using 80% of battery capacity and these Amp draws, I get 4.5 min at full throttle and 8.1 min at 60% throttle.

For thrust angle, I started with a neutral/straight firewall, then added a washer to top and right motor mount screws to get a slight right + down thrust angle:



Final weight w/out battery= 818 grams (1 lb 12.9 oz / 28.9 oz)
AUW with 2700 mah 3S = 1,006 grams (2 lbs 3.5 oz / 35 oz)

The plane balances perfectly at my estimated CG mark with the front of the 2700 mah 3S lined up with the firewall.

 

[aelflyer]

Maiden and Second Flight Video

Maiden + second flight video is up.

It flies really well.
- Takes off quickly and easily with only a little bit of up elevator. It's got lots of lift (watch the 2nd take-off, not the first )
- Flies predictably and clean in the air
- Loops are clean
- Rolls are slow, though likely faster than scale
- Stalls are gentle, nose dropping affairs. Nothing scary (see stall tests in video)
- Flaps slow it down a lot. This thing can fly slow, as long as you keep the power up. Drop the power with the flaps down, and it will stall quickly. Though I haven't tried a flaps -> down-elevator mix, which might help.
- Landing: Fly it to the ground, land at speed, don't back off the throttle. This is not a light airplane, and there's a fair amount of drag. I had a lot of "go arounds" trying to approach too slowly. I could feel the controls wash out as I dropped below its comfortable airspeed. Keep the airspeed up and it will come down smoothly. It really wants a smooth landing surface, but all I have available is grass.
- Design/build error: main wheels need to move farther forward (ideally axle should be at leading edge of wing) to prevent nose-over landings on grass/non-smooth surfaces.

 

[Grifflyer]

Awesome work aelflyer! looks like a great flying plane!

 

[unrauv]

I use mostly Gorilla Glue white, it sets up in and hour. I only use hot glue for fast hold bits. - My two cents.

 

[aelflyer]

Awesome work aelflyer! looks like a great flying plane!

Thanks, Grifflyer!

We’ll get the plans updated and will look forward to others hopefully building it. We are going to re-work the lower wing to move the mains forward. I’m hoping the end result is a plane that can cleanly land on grass without nosing over. Once we get that figured out, this should be reproducible. We also welcome beta builders if anyone wants to jump in and work out the remaining kinks with us.

 

[DamoRC]

Congrats on the maiden. All round this was a really nice build and the final product looks great!

DamoRC

 

[Tench745]

Looks beautiful and flies great. A little more flare on your landing might save you a nose-over. Moving the gear will definitely help though.

 

[aelflyer]

Crash Report: Time to Move the Wheels

The decision whether or not to rebuild the lower wing to move the mains forward just got a lot easier. I made the dumb mistake of not repeating my pre-flight check for my last flight of the day. I'd done pre-flights before all the other flights and thought, "I've already checked everything today, I'll just put it back up one last time."

It so happened that one of the flap servo wires had come unplugged from the y-adapter plug somewhere between the last landing, battery change, and final take-off. I put it up in the air and could not control the roll. The disconnected (unpowered) flap servo centered and therefore deployed the flap at 50%. Had I been able to figure out what was wrong, I could have deployed the other flap to 50% and flown it level to the ground. But I didn't diagnose the problem from afar fast enough. I fought the roll and managed to get it to the ground almost level, but it rolled right before touch-down and dug the lower wing into the ground.

Lessons learned: I shalt always do full pre-flights before every flight and I shalt tape all servo extension/y-connections.



The good news is that the retract mounts held, and the plywood/foam/screw lower wing mount held. The wing simply folded/ripped back near the root, one wing strut ripped, but nothing else was damaged. I actually glued it back together and it came out close enough to straight/true I could have flown it. The damage was shockingly small.

However, I really want to move the main wheels forward, so I ripped the wing apart after convincing myself I could have repaired it. I'm now using the original wing as my cut-it-up prototype to figure out the new retract servo/wheel placement.

The CG is 6.5cm back from the LE of the lower wing, the previous axle position was right about at CG (not good). I want the new axle position as far forward as possible, even if I have to add a wing root fairing and/or make wing/fuselage changes to hide the folded wheels.

Below are pictures of a mock-up of the new desired wheel position with wheels retracted. The retract unit will fit in the wing this far forward (5.5cm forward of the previous position) without modifying the retract mounts. The wheels protrude ~2cm forward of the current LE of the wing.

Now Fadi and I need to figure out if we'll reshape the wing root to conceal the wheels or create a separate fairing. I'm leaning toward reshaping the LE of the wing root so that the entire thing remains made of foam, but it's an interesting design challenge to make a folded LE that isn't straight. The easiest thing to do would be to angle the entire LE forward to create room for the wheel cavity at the root; however, this would make the lower wing different than the top wing and detract from the scale look. It would also be pretty easier to use the existing wing design and add a posterboard wing root fairing added to conceal the wheels. I really want to figure out a way to do this as an integrated part of the folded foam wing.

I'm going to mock up some ideas with posterboard and/or paper taped to the old wing. Suggestions welcome:




This is closer to the scale wheel placement. The real Staggerwing lower wing flairs in a wing root fairing shape:

 

[Tench745]

I think a combination of things could be done. First, maybe un-bend your LG wire. Then if necessary, rotate your retract so it's no longer parallel with the wings' leading edge so that the wheels will still sit within the profile of the wing, but still be at the right location on extension. Here's a picture to help explain.
Left: As is Right: angled mounting.

 

[aelflyer]

I think a combination of things could be done. First, maybe un-bend your LG wire. Then if necessary, rotate your retract so it's no longer parallel with the wings' leading edge so that the wheels will still sit within the profile of the wing, but still be at the right location on extension. Here's a picture to help explain.
Left: As is Right: angled mounting.

That makes sense, and thanks for the clear drawing!

However, there are two problems. 1) is that I'd prefer to leave the forward bend in the LG strut to get those wheels that much farther forward. 2) the struts are not made of piano wire---these are 3mm struts from the RocHobby Staggerwing that are super tough. I don't think I could bend them (precisely / non-destructively) if I tried.

For better or for worse, I'm committed to figuring out a way to create a leading-edge fairing structure (or somehow flaring the leading edge of the wing root) out of foam that hides the folded wheels. I just don't know yet what the structure is or how to build it....

Keep the ideas coming, and I'll post updates as I try things.

 

[aelflyer]

3-part wing

I think we have a solution. Sankaran Ramanarayanan gave us the idea to split the wing into 3 parts, with the middle part protruding forward with an angled leading-edge wing root fairing made of a nice clean folded foam edge. He uses a similar construction technique on his foam board B-25 bomber wing design.

I mocked it up tonight using some scrap foam board. This isn't exact, but this is roughly the shape we're thinking for the center / wing root piece. The existing airfoil will join with this on each side. Fadi is working on making an actual pattern for this, but here's a quick prototype:

 

[Tench745]

That'll work!

 

[aelflyer]

Iterating...

Fadi and I are iterating on the pattern now for the center wing section with 1 of the landing gear units temporarily glued in-place. Here is another mock-up using the old torn-up wing with the pattern for the new mid-section (a paper version) wrapped around the old wing as a "skin."

It's clear we have some fuselage work to do to clean up the nose; however, I should be able to use most my original fuselage/airfoil profile fuselage cutouts as-is because the airfoil shape of the mid-section will be identical to the rest of the wing. At least from the trailing edge up to the main spar, then the leading edge will change shape as the middle part slopes more gently out toward the extended central portion. It's going to be interesting to see how this folds when made of foam...

 

[aelflyer]

New wing/retract housing mocked up in foam

After hours of back-and-forth with Fadi, here is a mock-up of the new middle wing section built out of foam board mated to a chunk of the old wing. Folding the middle section with foam is interesting. There are a lot of score cuts at seemingly crazy angles to make this work, but the end result seems like it matches the main wing airfoil shape, does the job of hiding the retracted wheels, and should be pretty easy to replicate with the score cuts in the plans.

Time to build this for real....

 

[aelflyer]

Lower wing patterns, including score cuts

The pictures below are the 3 pieces of the new lower wing design with the printed pattern still (temporarily) glued on. The "ladder lines" on the pieces are score cut locations to create the smooth airfoil/3D shape.

 

[aelflyer]

Other responsibilities have kept me away from progress on the V2 Staggerwing, but it will get done. In the meantime, FliteTest just reviewed the RocHobby Staggerwing.

 

[miraspen]

I think with how complicated this build looks, you should do a build video when all the kinks are worked out.

 

[aelflyer]

Thanks for the nudge. I’ve been thinking about a build video. I first need to finish the V2 lower wing and get the plans updated. I’d be happy to guide someone through the build if anyone wants to be a beta builder.

I like the idea of doing a build video, but it’ll be a while before I can get to it. Let me know if you want to build before then.

 

[miraspen]

Am i doing something really wrong? I am coming across alot of problems. The cowl ring doesnt wrap around the front, just isnt long enough. Wing cut out on the bottom isnt even close to the wing profile. the power pod is too tall to fit in the power pod home. Also for me the tail is cockeyed. im trying to get it right but having a pretty hard time with this one. also the hstab cut out isnt deep enough, so dont glue it in till you mock up both Hstab and Vstab.