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FT Kraken, separable :The Hessian Ridgeback

#1
FT Kraken, Sepia-separable :The Hessian Ridgeback

Hi Everyone,

I've fallen in Love with the Kraken on first sight, but it's wingspan was going to be a storage and transportation problem for me, so before getting into ordering I put my mind into making this thing separable. (just in case, downloads for the scratch build are here)

I found some things from Multiplex, that function as a snap fastener (MULTIlockUni-Set Part Nr. 725142), but I felt not safe with only friction force holding my wing together, a form fit was much more what I was looking for.

Watching the Build video about 15 to 20 Times had me convinced I have a solution, but i would have to wing it as I build the wing.. So I placed my order of a Speed Build Foam Kit and electrical parts parallel to the Order to Hobby King, with LED Strips and Stuff. Idea here, was two Strips in the "front" part of the wing, iluminating it green and red (in compliance to Starboard and Port) and the whole Back section with one of those "multi color" things, flashing and making it fun to look at.

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Getting the Box was kind of unspectacular, the Tax was a not so nice surprise, (Europe) but I payed up and stopped thinking about it.

Datei 02.02.16, 20 23 42.jpeg
That's what I started out from... a full overview of what awaited me inside...

I started as the Build Video Suggested, but here is a Few things I'd like to add:

Opening the Foam for the landing gear was quite a pain when the Wing was already shaped, maybe that is something one could do before putting the Box spar on, while the lower side of the Wing is still flat. Just bend the Wire for the landing gear and fit it to the cavity, but of course don't glue it in yet.

The Build seems to completely leave out the coating of the Wing, or I'm missing that part. All of a sudden the Surface is shiny, and I have no clue how, what and when that got on there.

I did that just out of gut feeling before the box-spar gets mounted, mostly to protect the laser printed decal I put on the wing, which seemed to increase the force needed to bend the foam a bit.. maybe that is why I ended up with one slightly bigger Wing... it being my first bend of foam ever i might be ok... I did not dare to push as hard an necessary it seems. I'm sure it'll fly anyway. I used crystal clear packaging tape and re-enforced super strong tape, the first mostly on the surface of the wing, the later alongside all carrying structure I could identify. Mostly along side the Box Spar and what would later become the nose of the air foil.

First testing of the Lit wing.
Datei 02.02.16, 20 27 40.jpeg
As I played around with the LED strips I noticed that the controller of the programmable RGB LED has one function where he just permanently lights one if the three basic colors (Red Green blue). Needing to connect the controller to both wings, a I reused a male/female 4s plug and for the second wing i soldered it the way, than green and red would be switched. That way, when turning the controller to "green" the other half wing turns red, giving it the look you see on the pic. in some other config (like white and blue) the whole back section of the wing has the same colour. When setting it to "flash" ist makes psycedelic colour changes, that differ from left and right wing side, but you can't really tell. So, my switching two colours makes it even more colourful and fit my idea perfectly.

Then the moment of truth came, the Wings were supposed to be joined.

My Approach would be: Several link studs on two added plywood wing roots , joined with 20mm diameter and 2,5mm cross section O-Rings as a kind of cross thread.

In addition I found two support rods along side the existing Paint-stick-reenforcement useful. Now that These are in Place, I could imagine a laser cut set for the wing Separation as an option should pose no problem to you guys from FT.. give it a thought.

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As for the support rods, my choice was 4mm diameter. That seems enough for now, if I ever build another one, it would be more like 8mm Alu tubing and a pivot made of carbon fiber... feels better.. Also I'd add two Rib sections in the Nose and back section of the Wing, holding that in place.
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So why going through all this?
First, I got the impression the extra weight will not do any harm, FT loaded that thing with cameras, smaller rocket planes, net guns and what not. Secondly, now I can wedge in between both Wing halves whatever i feel like. All it takes is another Wing root-shaped plywood sheet that carries my interchangeable mid sections. Those could be "only" a battery holder or even FPV compartments or containers to drop things from, hell even a blunt nose-Pusher motor section could work.. I'm just keeping my Options open.

Datei 02.02.16, 20 16 00.jpeg Datei 02.02.16, 20 16 38.jpeg

I'll keep adding more details soon enough, for now wheels need to be acquired and the Wingtips need to get put on (I'll also make those detachable).

In Order to do that, I need to decide what to do with the landing skid. As suggestet by the original design, two wooden sticks are supposed to be glued to the Wing tip down side. I dislike this combination of functions of landing support and steering, especially since I want to be able to take off the Wingtip. Secondly I'm uncertain about the behavor when landing.
The Skid on the outmost far end of the wing will have an enourmous leverage, once it touches the ground while landing. Won't that possibly put the Kraken into a spin motion? or does that come in so flat that it will always touch down on the wheels first? As I will add support structure to the wings outer end anyway, I will put the skid on that (if at all), and let the wingtip just be a wingtip.

I'm also thinking about a reverse thrust function for Landing aproaches, having a Futaba programable radio with tons of extra channels and funny switches, can anyone advise on that? Overkill? Sure way of suicide?

Axel
 
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#2
Settings...

Ok, I started with the Ailerons... and I'm not quite sure this all works out.. First of all, I tried to put plastic hinges in, instead of using tape.. and they might have gotten a little sticky.. I#ll see if I can clear that out...
then: the Throw is way too big, allthough I was sure I used the same position of the wire in the servo and the rudder horn as in the build Video (a closeup on that would be nice next time guys)...

I never used a Programmable Transmitter before, so when looking for max deflection info I stumbled over "Throws: 35° deflection (elevon) Expo 30%" what the hell is that Expo .. WordlTrade show in Hannover? ... ok, no... I found This: and that was a helpful explanation


Detatchable Wingtips are on. love it. I put small wooden Stripes into the wingtips for support and used Wires instead of wooden kebap sticks underneath the wingtip.. wood felt kindof wrong. What (on second look ) felt also wrong, was having something Stick out of the end of my wing perpendicular, once the Wingtip was off..


COG is next, seems I need the Battery way to the Front if I don't want to add any lead...

Found a way to put the Lipo into the Wing instead of hanging it in the Wind (since seperable) and went for that option, needed to add 46 gramms of Lead to the nose (equivalent of 2 AA-Battery) though.

Loved the build, this was much fun, I'd like to make a build with my kid from scratch some day.

Hope I get it home in two pieces after the Maiden.. not in a Bag...
 
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#3
I've been looking at Hobbykings variable props on my project Vstol. It would give you differential thrust and reverse thrust for very short landings.
 
#5
Time for Specs

Wingspan: 1,83 Meter (6 ft )
Flying Weight: 1960 gramm (4.3 lbs) with batteries (1800 gramm / 4lbs 0 oz without)
Motor: Twin Emaxx GT2215/09 Brushless Outrunner (Power pack c)
Speed Control: 2 ESC - BL Heli 30 amp ESC (differential thrust for Rudder) (Power pack c)
Radio: Futaba FX 20 (Used: steering, throttle, left/right Aileron, toggle Switch for LED-Effects)
Prop Size: 9x4.7 counter rotating
Battery: 3S 2,2 / 2,7 Ah 25C
Flaps: no
Landing Gear: Kraken main gears with Wingtip Skid wires
Steering: 9 Gram Emaxx servo (Power pack c)
Experience Level: beginner / Intermediate (fly Phantom so far, some fixed wing experience waaaaaaaaayyyy back.. when Transmitter were still 40 Mhz)
Assembly Time: overall maybe 10-12 hours.. had to do a little every now and then,
 
#6
I've been looking at Hobbykings variable props on my project Vstol. It would give you differential thrust and reverse thrust for very short landings.

Can't the ESC go backwards other than re plugging the three motor leads? I did not look into this yet, but I was expecting those to run both directions if I wanted them to..
 
#7
no maiden

Still waiting for the weather to clear, we are seeing rain and strong winds...

lots of time on my hands to make final tweaks (neccessary or unneccessary)... found this:

balancing Props, should not only be a task for quad pilots, right?



(Caution, VVS-Detected!)
The guy used the App: iVibrometer (its 2€ in the European app-Store)

I found another similar App for free "AccelVisu" might work too... will give it a try next chance I get.

He put the small board with the mounted Motor and the wedged in iPhone on a layer of foam material, enabeling it to make small movements. Marking one end of the blade and running it gives you a certain type of movement. Sanding off some on either one end, running it again shows if things improved. In case it did, you are on the right side, and you take off as much as you need, if not, sand off on the other end....


I also found an App for a strobe light, trying to get both motors to run the same revolutions.. not quite there yet, the Wing and the LED's emit too much light ;-) ruins the strobe effect....

Axel
 
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#8

Did a roll out today, I guess the differential Thrust just acts like a Rudder, not any more not anything less. Not quite sure what I expected. I just rolled back and forth a bit on a playground nearby to get a Feeling how the Plane handles.

Also held it nose straight up and did full Throttle.. it almost carries it's own weight, but I guess it won't climb straight up. Seems the Motors Thrust is well balanced, had no Problems holding it with one hand at the nose as long as I did not pull side rudder.. the effect seems reasonably ok... But all the fields are still wet, don't want to risk ending up in deep grass and ruin the Plane even if I get it flown Ok.

I will have Patience... for ONCE :)
 
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#9
...Mor Basement Playtime

...since weather ist still questionable, I'm toying around with the plane.. found a shutter App for my apple device, playing around with the "wagon-wheel" effect on the Props, trying to find out if that way i could make them both have the same RPM's (uncertain how much that will really be of importance, since I'd rather want the plane to fly straight than be symmetrical while crashing..),

Conclusion is. Yes, you can showcase that effect, but the sound of the props will give me pretty much all the accuracy I need.. when they both hit the same RPM, the resonance does give it away...

The second application I tried was a vibration Meter, not much luck there either... yes it plots nice lines on the screen, but the effect was much better feel and audible..

Thinking about the hinge again every time I play around with it:, I'd suggest for anyone wanting to make this Plane separable too, do that just before you fold the wings. Simply align both halves and glue in Place the Hinge where the paint sticks sit in Front and back of the wing.. Then fold over the Wing and sand them to fit (the Hinge-sleeve material should not be titanium in that case..) Hinge material should be something like Fibreglass tubing... front I'd suggest 10 to 15mm diameter, back maybe 5-8mm
 
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#10
Took this form the Blog (that I actually just accidently started to be honest)

jonnyhyman;bt785 said:
Wonderful build. Thanks for all the important heads ups! These tips will help me on mine!

I've been searching for a way to make the wing detachable - and I love the plywood/O-ring solution. Elegant, light, expansible, and doesn't botch the laminar flow too badly!

Any tips on fabricating the wing joiner junction? Like you mentioned, I'll probably go for aluminum rather than the plywood.
Hey Jonny, thank you for you interest in this... sorry have to admit i still did not maiden this.. it#s sitting in my basement, but weather has cleared a bit I hope to catch a day without winds..

Well, I can just say, it all came out just fine in plywood (by "wing joiner junction?" you refer to the "Root wing" I assume, the two plywood parts with the buds to wrap the O-Ring around, right?)
I see no need for extra strenght of aluminum plus I think the glue will stick better to wood than a metallic surface... just a gut feeling on that one. ..but it would sure look neat if you have a Mill or water cut jet at your hand.. sawing that with a jigsaw might take a while.

I took the slightly denser birch plywood than the regular poplar Plywood, think it made a huge difference in strength.

Let me know how you get on with this task!
 
#11
...don't want to call it a maiden "Flight"... more a maiden odyssey... but! I did release the Kraken!

And here is what I found: On rough surface (I'm using a service Road between fields as take off runway) the Wingtip Skids have way to unpredictable and unstable friction. It's all a matter of leverage I guess, but at the tip of the wing, that is definitely not helping to get to speed and keep it straight at the ssame time..

I managed a lift off though, just to find me in a "stall" problem next, seems the Factory setting of the Ailerons is set to overshoot... or I'm tail heavy... I'll re-check that, but I was certain I'm ok on COG.

Well, I managed to keep it in the Air, but at full throttle the LipoChecker started sounding off low Voltage-alarm right away (I flew that lipo afterwards in my Phantom for 8 Minutes, so it was probably set too conservative) but I thought something is wrong and panicked a bit, taking back the throttle did not help much, plus it kept going away from me, and that is where the clean white design took it's tall, I could not tell if I'm upside down, left or what, Pulled into a stall again, managed to fly a turn, but again was not able to get it back closer to me.

At this point, I had gotten so low, that I lost LOS and all I could do was to just cut off engine and pray. Turned out it was in the middle of a flat field, standing nose towards me and except one torn off Aileron (I'll not try those plastic hinges again) it seemed fine.

So I'll be looking into a Tail wheel or Tail skid design, Replace the hinges on both Ailerons, re-check COG and work the Decoration a bit to be more distinctive...
 
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#12
...don't want to call it a maiden "Flight"... more a maiden odyssey... but! I did release the Kraken!

And here is what I found: On rough surface (I'm using a service Road between fields as take off runway) the Wingtip Skids have way to unpredictable and unstable friction. It's all a matter of leverage I guess, but at the tip of the wing, that is definitely not helping to get to speed and keep it straight at the ssame time..

I managed a lift off though, just to find me in a "stall" problem next, seems the Factory setting of the Ailerons is set to overshoot... or I'm tail heavy... I'll re-check that, but I was certain I'm ok on COG.

Well, I managed to keep it in the Air, but at full throttle the LipoChecker started sounding off low Voltage-alarm right away (I flew that lipo afterwards in my Phantom for 8 Minutes, so it was probably set too conservative) but I thought something is wrong and panicked a bit, taking back the throttle did not help much, plus it kept going away from me, and that is where the clean white design took it's tall, I could not tell if I'm upside down, left or what, Pulled into a stall again, managed to fly a turn, but again was not able to get it back closer to me.

At this point, I had gotten so low, that I lost LOS and all I could do was to just cut off engine and pray. Turned out it was in the middle of a flat field, standing nose towards me and except one torn off Aileron (I'll not try those plastic hinges again) it seemed fine.

So I'll be looking into a Tail wheel or Tail skid design, Replace the hinges on both Ailerons, re-check COG and work the Decoration a bit to be more distinctive...
Great info! Thanks for the heads-ups! Bummed to hear about the elevon being ripped off. I will also be looking into some kind of tailwheel. Keep us posted!

What did you end up doing to make the wingtip detachable? Working on that now on mine and wondering what works best!

Thanks!
 
#13
Great info! Thanks for the heads-ups! Bummed to hear about the elevon being ripped off. I will also be looking into some kind of tailwheel. Keep us posted!
Still not sure why the Wing tip Skid performed so poorly, I might have some Issue with the steering too, but I was alone, so ground start was my only option. Maybe a Hand start would show some other problems , next time I'll try this with a friend.

What did you end up doing to make the wingtip detachable? Working on that now on mine and wondering what works best!
Sorry, not beeing back to this project for quite a while,

For the detatchable Wing tip, I put some flat square plywood (about 2mm thick I guess), removed the paper on the Depron and sunk that in the Wing tip's surface after applying hot glue so it's flush with the outside surface and dispenses the forces evenly. I sealed it off with some Re-enforced package tape.

On the Wing I just made an extra Rib at the end and put in some wood thread piece in there that looks like this

$(KGrHqMOKo4E0WWw-6LiBNYRqIJLQg~~_35.JPG ..

I filed of the hooks at the end and Glued it it with epoxy with the washer part on the INSIDE of the Wing, make sure the holes in the wood for the tubing with the thread in it have a tight fit, works well, been using this on other projects before... no way that comes loose again.

I used Nylon screws, in case something breaks, I want it to be the connecting piece.

I have to get back to this .. but I don't see it for another month or so.
 
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#14

Did a roll out today, I guess the differential Thrust just acts like a Rudder, not any more not anything less. Not quite sure what I expected. I just rolled back and forth a bit on a playground nearby to get a Feeling how the Plane handles.

Also held it nose straight up and did full Throttle.. it almost carries it's own weight, but I guess it won't climb straight up. Seems the Motors Thrust is well balanced, had no Problems holding it with one hand at the nose as long as I did not pull side rudder.. the effect seems reasonably ok... But all the fields are still wet, don't want to risk ending up in deep grass and ruin the Plane even if I get it flown Ok.

I will have Patience... for ONCE :)
I really like your idea of reinforcing the wing like ribs at the joint.
The "rudder only" effect of differential thrust is what I like about it. Very flat turns like a 3D plane can make.
I was laughing when I saw your video about the rolls. I thought it was going to be rolls in the air. LOL
Also the sound of a twin is always great.

I am very interested in packable designs so I will look forward to your progress.
LooseBruce:D
 
#15
hi Bruce, on that playground surface skidding was no problem, I could even do turns (as you see).. it's some sort of rubber, made from recycled Tires or such... but on that concrete service ways I attemted to take off on it was a PINTA...

Will keep you posted.
 
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#16
Good news and bad news

..good news is, the Kraken is still in two pieces (not more) the Bad news:

Had no time for the changes so far.. need to get to it, summer is in full bloom..

-"time, all I need is more time.. hey, I have as much time as I want, i got a Time machine..."- Marty McFly
 

rockyboy

Skill Collector
Mentor
#17
Very cool build here - don't know how I missed this before! Really interested to see how it works out. That is a fair amount of additional weight for the separation supports, but as you mention the FT crew seems to put bricks on this darn thing and it still flys - just with a higher stall speed.

Good luck on your next flight - I hope we all get to see video of this in the air soon! :)
 
#18
Next Step taken

2017-04-08 11.14.04.jpg 2017-04-08 11.14.07.jpg

After last times problems with the ground start (which I kind of blame not only on my lack of flying skills, but on my design with the skidds on the Wing tips) I mounted a rear skidd in the center of the Airplane. No chance flying this yet.. but now (when on the Ground) there is only one dragpoint in the rear center. The Wingtip_Skidds are still on there, but hang in The Air about an inch when the plane is level, I assume this will come handy when Landing is a little rough... Will not be any good on a spot landing for sure...

I was under the impression, the Wing Tip Skids hat a really large leverage when starting the plane, if one saw a little more friction on uneven ground it would turn the plane sideways to easily while trying to pick up speed... well it's all mentioned above.

I also reinforced the Rudders, put additional hinges in (yes, I said I'd replace them, but hey, what the hell..) All that's left to do is change the Outer appearance a bit, so I know my Up and Down side and Stuff... Checked COG again, I'm definitely rather noseheavy than anything else, but that is on the Ok side..

This Summer it's do or die time! And I promise I'll put up a Video.. no matter what shape I carry this home...
 
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#19
..Did some Skidding test, it is way better than before, and i was off the ground for a split second there once, but It was very windy, and no desire to risk this, so I just keep to the ground. Noticed that the Skid kame loose, I'll have to put a little re-Enforcement like a Popsicle-stick in there or some...

I did play around with it to some extend, while the wind was strong enough to give the wings lift when it just sat on my hand felt right..