It's remarkable to see just how consistent the entire skin of the aircraft looks, the machined tooling has paid off so well. Most aircraft of this scale have noticeable waves and irregularities just all over the surface

@FarmerFpv

5 ай бұрын

It's bright white, lol.

@DrewLSsix

3 ай бұрын

​@@FarmerFpvplenty of other white planes out there

A&P pilot here, can’t thank you enough for all of the knowledge you’re giving! Keep it up and can’t wait to see the first flight!

One of the potential problems i have concern about is the spin recovery characteristics. The split rudder and location of the stabizer and elevater seem to be in positional relation ship to the rudder to cause "blanking" of the half rudder because the opposite half stays in neutral

We designed split rudders into the Lynx suborbital space plane we were developing at XCOR for similar reasons- it allows speed brake function and also was much simpler to actuate given their locations at the wingtips. We were also able to include a slight preload against the stop to provide greater resistance to flutter, important in a supersonic aircraft.

This whole project is phenomenal. I wish you lads the very best of luck in the future!

Always a great presentation… Tungsten makes an interesting choice. Density, and doesn’t corrode at ordinary temperatures of aircraft operation…. And not soft like lead. There is a recent AD for these elevator balance weights on a popular airplane because the weight was cast in a tube… and corrosion formed between the lead and the tube…. The corrosion forces expansion and the weight tries to fall apart. The problem took 20+ years to appear… but, once started the rate of oxidation increases, exacerbating the problem… Go DarkAero! 😃

Really proud of you guys, I have been following you guys for 3 YEARS. If I get a visa to the US, I must come and visit you guys. The consistency is amazing.

I used to fly the SAAB 340 and it had the most amazing redundant elevator system. Basically the left control column controlled the left half of the elevator and the right control column controlled the right half of the elevator. Normally they'd work together as one unit as there was a friction and mechanical plate that meant that if one side moved the other side moved as well. But crucially if part of the system jammed you could overpower the linkage between the two sides and still be able to operate at least half of the elevator. I always thought this was an amazing way to provide redundancy.

I never tried the split rudder although I thought a lot about it. I have flown canard aircraft so I understand the speed brake part of it. Good job! Also it looks like you have some differential in the ailerons. Very good! Something I did a lot was flattening and widening the aileron counterweights so they tuck up inside the wing tips only when the aileron deflects down but the weight enters the wind stream when the aileron deflects up. This adds some parasite drag to the to the up aileron side of the aircraft thus reducing the amount of rudder required to maintain coordinated flight. It's good to see some young people that know how to think out good design. Keep it going and be careful. Thanks for the videos!

The independent rudders are great. A very safe way to operate a speed brake without forgetting the boards are out. Yes, this happens, even with highly trained and experienced airline pilots they forget to stow the speed brakes.

Nice, heim joints, bell cranks and torque tubes, with not a whole lot of translation, so backlash should be minimal. You might want to also mention that the control surface weights, by projecting up into the airstream forward of the hinge point, also help manage control forces at higher airspeeds. The split rudder works VERY effectively as a speed brake, I use them this way all the time on my Cozy. I am curious what you're using as a rudder return spring - it looks like you're using push-pull cables to actuate each rudder, but I don't see space inside the rudder for a spring assembly - is it at the pedal end? If so, how do you plan to prevent buckling of the cable in push near the pedals if there is resistance at the rudder end? You'd need a decent sized spring to overcome the friction of a push/pull cable that long. Do you engage the brakes master cylinders only after you get full rudder pedal travel? How do you ensure you can land with the rudders deployed, but without the brakes deployed? (I'm assuming the nosewheel is full castering?) Lastly, I didn't see the roll servo, I'm curious as to where it's going to end up - it looks the only practicable place is behind the seats?

@kadmow

7 ай бұрын

- How I heard it, the rudders are independent - with only a pull cable (spring return to centre) - ??, is the rudder deviation only from centre to full lateral deflection (left or right) ? - OR having no centre stop, the lee side rudder (low pressure) just follows the pressure side (half) to full deflection under spring action? - using the airbrakes on a steep straight-in approach sounds kind of similar to balancing regular toebrakes for yaw control, from the sound of it.. hmmm... Some high performance lightweight RC craft also only use a (single acting) pull cable (kevlar thread/kite-line often used) for tail unit control, the tension is maintained by spring tension as is full tension deflection - balanced by servo force - (spring-pull rudder and elevator - no tensioning problems or slop can intrude)

@Skinflaps_Meatslapper

5 ай бұрын

I think they're making a mistake with the split rudders in the way they have them designed. They really need to follow each other at least somewhat past centerline for the first third of their travel before splitting, with canard aircraft a little misalignment doesn't come with a drag penalty but it certainly will with a split rudder, and especially so with conventional tractor configuration slipstream hitting the vertical. There will only be a single speed and throttle setting in which the two rudders are streamlined and together, the rest of the time one or the other will be split, meaning you'll always have a small amount of airbrake deployed. The rudder pedals should also be interconnected in their movement with airbrake function as a separate lever to actuate that simply moves two pulleys to shorten the rudder cables. This would allow standard toe brakes to be used instead of pushing the pedals to the floor and forcing the airbrakes open in order to make the toe brakes work, or having to use the dreaded piper style hand brake. You may not always want to use brakes with the airbrake deployed for whatever reason, and not being able to put any pressure on the rudder pedals during flight to avoid deploying the airbrake is going to suck.

What about ICING inside the split rudder design? Will you test the push force overcoming ice adhesion? Another option is adding heat for safety. Love the concept, but Ice and Breaking concern me.

@purge98

7 ай бұрын

Very good point.

The Long EZ 'rudders' are somewhat required to be airbrakes, since they use a different principle to normal rudders to yaw the plane. Normal rudders apply lateral lift to the tail to pivot about the center of gravity. Since the Long EZ rudders are more to the sides rather than behind the CoG, the force required to pivot around the CoG is almost straight backward, ie, drag. And they need to be differential so that their is a net torque. If the EZ rudders were set up to act in unison, in the same direction, you would find that it would barely yaw.

@cyanoacry

7 ай бұрын

edit: I checked my plans and the Cozy definitely has a shorter rudder moment arm than a comparable 172, previous comment deleted. oops!

Great video, as always. In addition to clearly explaining the basic operation of your control system, I especially liked how you quickly touched on the considerations that went into the design; such as goals to minimize friction, backlash, compliance, and weight while also ensuring easy of service.

Your explanations are always so good and easy to understand, great project!

Very interesting rudder design, really clever double identity for a rudder. However, even though I don't see this bird doing dive bombing, the dive bombers in WWII also had an air brake, which didn't work until they poked it full of holes. Before the holes, the dive flaps ripped themselves off the airplane in some dives. There's going to be quite a vacuum in between your rudder panels. They're also small, unlike the surfaces of a dive brake, so making them work without unexpected consequences should be easy. Holes near the very front of the control surface should do, and won't interfere with the forward flight aerodynamics of the surface, but it will do the pilot and structure a favor. They can be made as decorative as they are functional.

@LawyerPapa

7 ай бұрын

I was going to mention the drag. If you need to fly with a trim, you'd be flying with a parasitic drag. Anyway, yours went well beyond that!

@CrossWindsPat

7 ай бұрын

They didn't have carbon fiber back in WW2. But it is a good idea if they need to.

@CrossWindsPat

7 ай бұрын

@@LawyerPapa Ouhhh thats a solid concern.

Great explanations and great looking airplane! Reminds me Mike Arnold's AR-5. Thanks a lot for sharing

Always informative guys!

This project is hugely inspiring, you guys rock! Cheering you on

Your project is next level. Love it!

Ngl, I love everything about the split rudder aside from the control scheme you've selected. Conventional rudder pedals (push one and other moves opposite) with a seperate speed brake lever similar to what youd see on a jet's throttle quadrant would be much better as far as avoiding inadvertent speed brake application and making the transition from other aircraft more seamless.

@daviddavids2884

7 ай бұрын

ngl, yeranidiot see my comment above

Can't wait for the first flight. Amazing work guys.

Great video as always!

This plane looks so good, love your vids, thanks

Interesting rudder/spead brake. One thing I wonder about is propeller slipstream. On the Rutan canard airplanes the vertical stabs and rudders are outside the spiraling slipstream. On the DarkAero, it will be in the slipstream. I'll be interested to see how you deal with that, as well as rudder trim. My understand (which could very well be wrong) is that on the Rutan canards, the rudders on the winglets is more about creating drag rather than lift. Same goes with split style of flaps on other airplanes. I'm not an aeronautical engineer so I might be all wet... I'd like to see your split rudder act more conventionally with the rudder pedals and have a separate mechanism to split them. Kind of like the A-10 ailerons do. Hmmm... Or.... Leave the rudder conventional an put the speed brakes on the ailerons just like the A-10's! Keep up the good work.

@schnka

7 ай бұрын

I agree with you. Rutan design is based on drag. In conventional control surfaces it’s the back side of the control surface that moves the airframe. It’s a wing you might say creating lift. Left rudder input means the right side of the vertical fin and right side skin of the rudder making a positive airfoil moving the tail in the left direction. I question if this will work well. I’m not an engineer but have been designing and building model aircraft all of my life for 50 years or so. Have studied design for decades. I guess we will know one day. Great project!!!

Is there an expected loss in rudder authority with your design compared to conventional designs, since only half of the rudder deflects with say a right rudder input. Wouldn't the fact the left half of the rudder remains within the line of the airflow "block" some of the airflow from adhering to the interior side of the deflecting right rudder and therefore reduce effectiveness?

@givenfirstnamefamilyfirstn3935

7 ай бұрын

It looks like it shifts the air flow point of indecision on the leading edge so that more air will flow over the clean side and move with higher speed giving more lift. Will it be _efficient_ and forceful enough for fighting *repeating* turbulent air gust rapid wing rises or more importantly immediate effective and powerful spin recovery? Imagine an inadvertent spin at aft C.O.G. with those pretty, narrow wings.

Such a gorgeous plane

Beautiful thinking . It made me happy as same as seeing Beautiful paintings

Man. She is really coming together nicely. I really can't wait to see how that split rudder works out. Seems like a great way to add drag when you want it to slow down such a slippery plane.

excelente video, keep it up

I have now watched every one of your videos, some more than twice. Its wonderful to witness the evolution of modern design and materials taken to their absolute limits for your mission. The videos are so informative, easy to understand, and the plane is absolutely gorgeous. When it comes time for a DarkAero II, how do you feel about a plane with a 55mph stall speed, fixed gear, fixed pitch prop, 200mph cruise, similar mega-range? Come on, add a couple of feet to the wing, a couple of inches to the cockpit, use that UL520T so we can outclimb the weather - this will be an rv-14 killer. AKA, something us mortals can safely handle and still get insurance for (not to mention have a better resale value)... Just food for thought, keep up the good work, and keep the videos coming.

Impressive work.

The split rudder is so sick

@ddegn

7 ай бұрын

I agree. I imagine there's a small aerodynamic penalty to using split rudders. I'm pretty sure the split rudder has more drag in use than a conventional rudder. Having a speed brake likely makes any loses worth it.

@fdelacou

7 ай бұрын

Was wondering if that could be a replacement for ... flaps. Thoughts?

@gpaull2

7 ай бұрын

@@fdelacou- It could replace flaps for giving drag while reducing altitude without gaining airspeed. Won’t add lift for slower takeoff and landing speeds though.

@charlesseymour1482

7 ай бұрын

No! Not sick but good!

@timduncan8450

7 ай бұрын

@@fdelacou NO. Flaps increase lift and drag, important to minimize and bleed KE during landing. Lift is critical for this. Flap extension is typically not allowed at high speeds due to high loading they can create.

That is a pretty sweet looking plane! ✈️

Seems like it would create a lot of drag in normal flight with the split rudder. Example: prolonged right rudder on climb out leaving the open-V trailing vertical stab.

@rdyer8764

7 ай бұрын

Seems so to me too. What say you guys?

@cabanford

7 ай бұрын

Speed break is cool, also wondering why both rudder halfs don't both go left/right?

@DarkAeroInc

7 ай бұрын

The rudder deflection to trim the aircraft in climb or during normal maneuvers is small. The drag of the split rudder isn't much different than a conventional rudder for small deflection angles.

@cabanford

7 ай бұрын

@@DarkAeroInc Thanks for the reply! So loving the epic engineering quality of this project ❤️❤️❤️

@21trips

7 ай бұрын

@@DarkAeroInc Since the rudders are the speed brake, can you turn on the ground and speed brake at the same time like a short-field landing?

8:15 i've always wondered why more planes don't have that, its like a really easy way to reduce speed. glad to see the team incorporating that design into your aircraft though, keep it up.

Was wondering about flaps. Glad I'm subscribed (11:40).

You guys are awesome! Everything is very well thought out. The split rudder is a great feature. Using it to slow the plane down is very nice. I have to ask, in turns, does the other half, the straight half, hinder the turning ability of the turning half, enough to notice? Do the halves open up enough to maybe offset any drag? Again, great job! I hope to have the money to buy one of your airCRAFT one day! Take care

You guys are SO LUCID. Actual role models

How are you guys running brakes and steering with top mount lever pedals? And will there be anything in place to ensure that resting on the pedals isnt going to cause constant airbrake? Also how are you accounting for the need for trim?

We need so many more videos. Just normal everyday stuff. These are awesome

Great work in there, thanks for sharing this video. One question, why choose one split rudder movement to stop in the yaw and not make it all the way together with the other part? Wouldn't this create a greater drag while yaw?

Cool. Please get into more details.

In 1965, the Payen Arbalète PA60 was already using such a system that inspired Rockwell for the space shuttle...

Amazing video as usual. Just curious to know which camera do you use? The auto focus is sharp, fast and accurate.

The most advanced airplane 🛫 today 🛫🤙🏻🏆☝🏻💪🏼 looking forward to more videos ty

I didn’t hear anything about designing out flutter? This is of great technical interest to me. It is also the practical speed limit for many airframes, assuming they have lots of hp like this one. Would especially be applicable to high powered turbo normalized aircraft

You might want to consider a lockout for the split rudder for takeoff and climb. Canard flyers of various makes have had issues during engine outs of panic stomping on both rudder pedals, exacerbating the emergency. This is of course, alleviated with training. Also, a lockout would keep the passenger from inadvertently inputting while shifting their position, ect.

@willasproth

7 ай бұрын

Does a control lockout not have its own safety challenges?

@DarkAeroInc

7 ай бұрын

You wouldn't want to lock out the rudders during takeoff, climb, or any other phase of flight since they are required for directional control.

@codeforge3301

7 ай бұрын

@@DarkAeroInc only lock out the split rudder functionality. When locked, it should behave as a conventional single rudder

@LThorsen78

7 ай бұрын

The ability to flip a switch to convert the rudder(s) into a single control surface would inherently be safer. (If this function is actually desired) Failures to the pins/flanges shouldn't lead to any particular dangers.

@LThorsen78

7 ай бұрын

@@codeforge3301 This is what I meant to convey. Thanks.

Do you have any aileron differential? Have you calculated expected adverse yaw and does it matter? Will the air brake rudders affect pitch or just speed (via drag?).

How does the roll not bleed into pitch control? When you move the stick sideways, it seems that the pitch linkage would move a bit forward?

Every one of these videos teaches me something. You make complex concepts understandable, and most importantly, you give your audience credit for having enough intelligence to follow along with you. Much appreciated.

As always the ailerons will create some adverse yaw that will have to be counteracted by rudder. Unfortunately the split rudder is going to cause a lot of drag during routine turning.

Any reason you used torque tubes for the elevator and ailerons instead of cables? I happen to be really familiar with a specific aircraft that only uses cables for its flight controls so seeing torque tubes was intriguing. Thanks

I noticed you have an elevator servo connected to the linkages. The rudder control cable system as well as the ailerons do not show servo’s though you did mention servo’s related to a future video on the split flaps if I heard you correctly. At the very least having some sort of trim tab on the rudder would significantly lower the pilot workload on long distance flights. Could this form the basis for a 2 or even 3 axis autopilot system?

Very cool, congrats on the innovative design! I'm still looking forward to HS taxi testing/ TO roll testing. I looked at the similarities/differences between the DarkAero and a TBM for TO roll (for P-factor). They are somewhat (loosely) the same. The TBM has a large rudder, and needs it to hold center line on TO. It will be interesting to see if the split-rudder will also hold center line at full TO power. I'm rooting for you guys! 8) --gary

Are you guys concerned about the pressure drag vector that is opposite the way you are trying to yaw due to the split rudder?

So everytime using the Rudder deploys the Speed Brake every time? Even trimming the Rudder results in more drag? Does DarkAero have Directional Stability problem that your trying to fix with the Rudder Speedbrake? Wagging the Tail, reduced by deploying Speed brakes with Rudder deflections?

How bad is the performance loss during initial climb when using a lot of right rudder? It seems like you’d be trying to climb with the speed break basically partially deployed if you have a consistent rudder input in

11:00 instead of increasing the arm length to balance it, what if u add a cavity inside the wing and have the aileron elongated along the entire tail, distribute the weight in a short depth and it doesn't interfere with the airflow?

Is there any increased icing risk in the split rudder?

How will you handle constant yaw inputs in cruise flight? Won’t a constant split be inefficient?

@pilotavery

7 ай бұрын

Like any airplane, the pilot has to learn its quirks. The cork of this is you can't push hard on both of the rudder pedals at the same time

Do you have enough leverage for one hand to over come the forces on the ailerons control surfaces? If you have 1:1 ration on the torque tube then the only lever advantage is the length of the stick. 🤔🤔🤔🤔🤔🤔

I'm really curious about the single split rudder. Wouldn't that increase drag any time you use the rudder in a coordinated turn?

Is there a differential in the ailerons between up and down deflection or is the travel the same? Cheers and good luck.

With the rudder pedals doing so many things, how do you apply the brakes?

Can't wait to see it fly.

Why is the fuselage so long? Could the cruising drag be reduced if the empennage is closer to the cockpit?

This is pretty slick. You combined the dual rudders of a Rutan VariEze into a single unit. 👍 Edit: I should have finished watching your video before I commented. At the 8-minute mark you talk about the VariEze.

Great and enjoyable videos. My question is, is the darkaero going to have a pressurized cockpit?. However is the build of a pressurized cabin just dependent on the strength of material only or how is modelling a design for a pressurized cabin achieved, are there computations?

@DanFrederiksen

6 ай бұрын

it's much easier to do pressurized with a round cross section like a balloon. This plane is more boxy. It's not impossible but flat parts need very high strength and the canopy edge and latching mechanisms have to be very strong as well. The 'glass' would be thicker too. Or would have less glass, more or a hard top with pillars like a car, maybe. No pressurized GA plane has been done with a clear canopy afaik but not impossible. Fighter planes have it.

TECHICAL PTS ONLY Your rudder is just skin. It should've ribs. Otherwise, it gonna collapse under aero load, locking its hinge, making it catastrophic. Too many linkages providing failure pts. Trim tabs is another set of failure points...Instead give trim tabs on stick like RC model Longer control horns proportionally minimize backlash.

Clever design choice with the split rudder/airbrake. For better or worse, this style of airbrake doesn't reduce lift when deployed. Wing spoilers have the benefit of increasing tire traction, although I suppose they have their own concerns, such as difficulty in packaging without a drag penalty. I'm curious how the split rudder's drag compares to a hinged rudder at modest deflections (e.g. trimmed for P-factor at cruise).

Are there no vortexes produced at the end of the wings, increasing drag?

I would love to see the pedals in the cabin to see how the brakes operate with the split rudder system. Please include that in a future video!

Love these videos. Would you be willing to do a video on the business model/plan? Curious how you see the DA fitting in around the Lancairs and RVs of the world

I am really not impatient for this project to be done, as your videos are so educational and well made. Thanks !

How much slack in the controls is acceptable? Years ago I was flying AA5As, and some of them seemed to have 15 degrees of slack at the yoke for the ailerons.

We're spoilers considered over or augmenting ailerons in the interest of mitigating adverse yaw ??

Why is your elevator torque tube off the center of rotation? Space constraints?

I can't wait to see it in the air.

what are you guys doing about confliced input /panic input on the rudder? you might just end up with a huge speedbrake deployed at takeoff

You say that it's kind of complex but it's about the most basic way you could do it with hard mounted components. Nice work.

The rudder looks a little small for slow speed.. does the nose have positive steering or free castering?

Love the plane! One question though, how do your wheel brakes work? Guessing no toe brakes?

Please explain the split rudder more. I see impact force vs lifting force as one side stays flat (stream lined) while the other is inducing drag. Is the concept the same? Are there efficiencies in stabilization with the split rudder?

@NickOakley

7 ай бұрын

I don't get this either. The VariEze uses the split rudder to add a little extra pro-yaw drag out at the tips as well as the normal yaw moment, but I can't see the advantage of this on DarkAero because you're adding extra drag down the centre-line.

How do the wheel brakes work with split rudders?

Is right rudder only or left rudder only not going to act like an unwanted air brake ?

Very nice project. I would not do split rudder, I think it mostly generates drag not yaw moment. For EZ planes "draggy rudder" works because of different location of the rudders.

I didn't see any mention that the long torque tubes through the wings, at the cabin, don't pivot at the tube? Hard to explain, and I don't have the correct vocabulary to properly describe, but watch closely at around the 6:00 mark. The inboard bell cranks are anchored on one of the ears?! Is it very weird that the inboard ends of the torque tubes move up and down in space?

So impressive. Range and cruise speed are unmatched. I'm a simple RC pilot. But enthusiast or not, who doesn't think this thing is awesome!?!?

You should reconsider the current rudder actuation. As @aaronhammond7297 mentioned in a comment a few days ago the Long EZ 'rudders' are somewhat required to be airbrakes because the force required to pivot around the CoG is almost straight backward, ie, drag. Which is not true for your design. Every time one will actuate the rudder it seems that it will also create some serious drag, due to rudder's size. Considering that you designed the plane for speed, that's a major oversight. Sometimes being different is not being better. You can keep the split rudder design, but the halves should move together, unless the brake is actually wanted and applied intentionally some other way.

Yes. Serviceability is flight critical!

I really like the inclusion of the dual yaw rudders as an airbrake as well. glad i found yalls channel and congrats on all the progress

One doubt, the split rudder can in thesis act differently because both sides would never act equaly and cause yaw?

Thing of beauty.

Does split rudder add to STOL capabilities?

You've probably already answered this but how is trim done?

Looks las though it'll be a nice, crisp handler. A little bit of friction in the systems isn't bad as a damper of oscillations. It will be interesting tosee how you handle trim, and how you achieve differential on the ailerons.

Very cool. You didn't mention nose gear steering. How will that work? Maybe include with the secondary controls discussion?

@nathanbanks2354

7 ай бұрын

It looks like it's castering (kzread.info/dash/bejne/emyJycprlt3KYKw.html) but this still involves controlling the braking mechanism. I didn't look carefully for past videos on this.

@alexanderarnett4966

7 ай бұрын

Yes they chose to go with a free castering nose wheel. Steering is handled by differential breaking and rudder at high ground speed.

I've seen split rudders but I'm not sure I've seen that control scheme for the rudder only moving one side at a time, interested to see how y'all came to that decision and how it changes things like spin recovery. Obviously would imagine it would be at the worst a negligible impact but are there any major advantages to this aside from weight saving for having a speed brake?

@CrossWindsPat

7 ай бұрын

Its just the speed brake. Its a debatable function but one could argue its safer to be able to control your speed at will than the negative consequences from the spin characteristics. One thing is for sure, I dont see split rudders on every plane and there must be a reason for that.

What have you done to control adverse yaw when applying the ailerons?

@givenfirstnamefamilyfirstn3935

7 ай бұрын

Time 2:35 shows differential movement, more drag on the inside lowering wing.