One thing that impresses me is the enthusiasm, confidence and logical thinking that oozes from these three young men. I'm a bit taken aback at all the non-traditional material, methods and design. Carbon fiber, hinged canopy (and panel!), split rudder, tiny wing, UL520 no mixture control engine. This is a far far cry from the dowdy traditional C172 I fly. In fact the modern futuristic Darkaero makes the C172 look like the Ford Model T of the sky. They believe in themselves, and in their product. They do everything totally hands-on. If that's not full conviction I don't know what is. Way to go, bros! And my very best wishes from faraway Malaysia!!
Been very impressed with darkarea. The quality even in prototype form looks good. When I’ve asked a question or left a reply in the comments I get an answer that makes sense. The stress testing will mean that the aircraft has a better chance of obtaining approval outside the USA.
Nice vid on DarkAero. Those guys really give us all the detail and it will be nice to see real performance soon. I like your narration and the whole style of your video. Thanks.
What I like about these guys is though they seem wet-behind-the-ears in trying some of these new things like the split rudder and the electric gear, they also have the analytical chops and the rational attitude that I trust them to swap them out if they're not working, rather spend dozens or hundreds of pounds to satisfy their own egos like certain other would-be kitmaker youtube personalities.
Based on many of their comments I've read these guys also seem like they would be willing to accept/seek outside help should they stumble into something they cannot work out on their own. I'm only disappointed that I can't fly a darkaero with my light sport license and that it is a bit beyond what I can afford.
@@rv6ejguy I’ve been a subscriber of yours for a long time. I really enjoy your content and technical info, I’m following the darkaero project closely and love the work they’re doing especially around the gear. Please keep us updated. I always request them for content on the gear. I operate and represent BlackShape and their aircraft use electric motor drive undercarriage with lead screws. No problems there
The DarkAero has the potential to be a big success. The team's philosophy, professionalism, work ethic is something to be admired. The only factor that I can see against its success is, unsurprisingly, cost. The company will undoubtedly find a costumer base. I just hope that enough costumers will be there to justify the investment. Other than that, the aircraft itself is an absolute jewel. If I could afford one, I would definitely purchase one.
@@rv6ejguy I agree. It should be in the air as soon as airworthy; not as soon every single nut and bolt has been polished to perfection. It should be in the air as a proof of concept. Non-critical parts can wait. Getting it into the air will incentivize investment, as well as potential customers, not to mention the value of publicity.
@@leoa4c Yup, last video was on creating a CAD catalog. Nice thing to do but is taking time away from DA which has seemingly slowed down a lot over the last 6 months.
Much as I like the professional approach at Dark Aero, only finishing the the aircraft and flight testing it will prove the performance projections and specs. After that, it's another big project in itself to start producing kits. Still a long ways to go here...
These engineers have set THEIR goals (not ours). Very light. Fast as possible. Best range they can muster. AND...for better sales... side by side rather than tandem, and LOW PRICE- that means staying under FL180, non-pressurized, simple flaps, no slats, no speed brake (using split rudder instead), and the fastest stall speed allowed.. The UL engine is the lightest weight for the horsepower, and they say the electric adjust prop is much lighter than an oil pressurized one. They also say the prop was designed for this engine, and they plan on using full RPM of the engine for 200hp. I believe they will come in at their weight goal. Their speed goal seems too high, but they still believe it will achieve it. Their extreme attention to details and testing and designing for production and easy kit-building are their greatest strengths. Try finding a 275mph plane for $160,000.
Awesome! I hope they document the testing like the Wasabi guys do. It could be a chance to show any problems that arise, and how detailed they are when they solve them. Most importantly, it would be extremely interesting and fun for me to watch!
News alert,, that UL engine is now turbo normalized. 220 hp. Go high go way faster. Also with say an extended tip option cruise would improve with altitude while helping tame the stall speed a bit like 65 or so.
Very well done videos and a lot of fun! I'm not sure they couldn't make the spinner one piece though with matched tooling. I built a rocket fairing with a carbon fiber 20 ounce 2 harness twill and no special tooling. Matched tools and the right fabric could probably make this a one piece part. I'm also concerned that having to use some constant right rudder to offset engine torque would set up a permanent split in the rudder adding drag while in cruise. They also discussed the higher aspect rudder for more efficient lift right after saying their cross country mission profile made rudder usage (lift), less of a problem. Higher aspect has greater Moments of Inertia requiring more strength and that requires greater weight. So lower aspect seems more consistent with the mission statement. maintaining
Really enjoying the DA build vids. I'm curious about the split rudder authority. The Bugatti used a split rudder and fowler flaps, I think. Its the only other aircraft I can think of with the split rudder config. I'm hoping there will be a future DA model that is 4 place and turbo-charged. Cheers.
They are an impressive team. Design-for-manufacturing (DFM) is key for any manufacturer, and often overlooked. Its ideal to include all of these disciplines together at the start of a design, rather than having a departmentalized, waterfall process.
Thanks for looking at the DarkAero. I also think the brothers are doing a great job. There are two things about the airplane which don't seem right to me. One is the way the instrument panel is connected to the canopy. This seems like the wires going to instrument panel will be flexed more than in a stationary instrument panel. Hopefully this isn't the problem I fear it could be. The other aspect of the design I wonder about is the engine mount. They plan to use a pair of aluminum boxes (of sorts) to connect the engine to the firewall (with shock absorbing mounting points). This mount is much smaller than the normal welded tubes of other engine mounts. I'm concerned the smaller mount doesn't provide all the benefits of the bulkier mount. It just seems like the conventional mount wouldn't be as bulky as it is if there weren't a good reason to make that way. Again, thanks for the great video. I really enjoyed. I also really enjoy watching the DarkAero videos.
The flat six with EFI should be glass smooth compared to a 360 Lyc. and the plane is only stressed for 3.8G I believe. I think the aluminum mount fits with their philosophy of using machines (CNC) to make as many parts as possible. This layout eliminates hand fitting and welding tubes. We'll see how it pans out. Some things probably won't work as planned but I feel they will accept this and re-design any parts that don't.
@@rv6ejguy Thanks for the reply. I hope things work well as planned and as you say, they're make changes if needed after they test. It's a lot of fun watching a project being done so well after seeing all the problems plaguing the Raptor. Thanks for making your videos.
Flexing the wires by opening the cockpit should be no problem if they are properly flex and strain relieved and protected against chafing. I work on machines that get way more use than an aircraft cockpit and wire flex is no problem. Of course there is no worry about falling out of the sky either. But I can’t recall there ever being a problem caused by flex in 40 years of working on them. Improper strain and flex relief modification in the field by thoughtless techs usually causes any issues. That or improper use by end users.
UL Power have now turbocharged this engine. It will be a game changer, for sure, and it is called the UL520T. ulpower.com/en/engines/ul520/ul520t This engine now makes 220 HP at a more propeller friendly 2,700 rpm right up to FL150. It can produce 200 HP at 2,450 rpm and a continuous cruise power of 180 HP at just 2,200 rpm. Higher power, lower rpm and maintaining power at altitude will make a huge difference. The DarkAero 1 does not have much space between the engine and firewall but hopefully there will be enough room for the turbocharger. I do wish that each wing gets extended by about 1 metre. Glssair did this to the III transformed it with increased cruise speed and climb as well as reducing the stall speed.
Wow - that is interesting news I hadn't heard about. The tradeoff in terms of weight for power is not bad it doesn't look like. The high altitude performance also better obviously. How does increasing wing increase cruise speed? Or is that just with turbo + wing increase?
@@randominternet5586 The designers have made cruise performance at non-oxygen altitudes their primary design goal. In airplane design there are compromises. The small wing won't be good up at 18,000 feet or for slow flight. It's hard to have it all without giving up a bunch of knots on the top end. RVs do the medium speed (around 175 KTAS) and low speed compromise well and with massive market share. Not much point in trying to compete there. This is a small plane but follows the Learjet theory- the high speed means you won't have to sit in it too long...
I'm surprised they didn't go with a Rotax 915.... Although only 140 hp, it is turbo normalised, so more powerful at altitude than NA. Power loss is 3% per 1000ft for NA.....
Been watching their videos as they get the plan put together. It seems to compare to the Lancair 320. My hope is that this plane will have better flight (and particularly stall characteristics) than the Lancair. I read somewhere that Lancair kits make up a ridiculously high percentage of all GA crashes. Hopefully, these guys will make this a fast, yet SAFE airplane.
Fantastic! RU-vid got this too me. Very interesting analysis. Designs almost ALWAYS come in heavy but will be interesting to see where they land - very curious about that! They've got FAR more engineering into this than a lot of others, good mix of skills so very open minded as to their success. Focused on long / cruise flights clearly. I'd personally trade out a touch there but... they know what they are going for. ROC seemed high but I did no analysis, even 2,000 is fine. On engine choice - another poster notes there is a turbo version of this engine. The thing is already plenty fast. Maybe a Turbo version if they can prove the concept and might be a bonus on engine choice longer term. The range is impressive for the weight / size. I hope the autopilot is good and seats comfortable, that ends up being some real hours in terms of flight time. Where this get's really interesting is below gross. They should charge enough for their work in this, start with a premium price on the kits and then bring down over time if possible. I hope they get flying and make some money. Thanks so much for doing the video - enjoying theirs and now yours on this project. Only thing I'd love if someone added some wing loading / power loading numbers for comparisons. I might come back on weekend to add that when I have a bit more time to sit and look.
I bet they'll go for more iteration on the initial design for a DarkAero 2/3/4/5/6, different features, engine options, more passengers, etc. A turboprop/pressurized version seems like another logical step for this very gifted team. I don't think they want to go the CubCrafters route and charge a premium and limit their user base. Mass market appeal is where it's at.
@@Zav Except cubcrafters have a great business AND do good volume. The engineering for pressurized adds a fair bit. Should be fun - a 4 seater / turbo versions maybe some options.
I wouldn’t think twice about putting my life in the hands of a few young chaps with possibly less than 10 years aviation experience and 1 build between the three of them. I can’t see this endeavor being anything less than smashing. No pun intended! Brilliant! Cheers mates!!
My bet is that you've never built your own experimental aircraft. The homebuilder is ultimately even more responsible than the kit manufacturer to ensure that the plane is safe prior to flight testing. This plane will be a huge commercial success, and very safe. Most other kits do not even test their critical assemblies. You probably should stay on the ground with your negative attitude anyway.
@@FlightMojo well then your bet would leave you broke and as a result you probably won’t ever live independently. In other words you have absolutely no idea of what you’re talking and you appear to know even less about aviation safety. Get a life. Seriously!
They might achieve a lower than anticipated empty weight. As they're building, they have been finding lots of opportunities for weight savings from using different materials than initially planned. One example is switching to a polymer bearing/bushing for their landing gear shock absorber instead of bronze (?). I've been very impressed. I need to see actual flight testing and validation of their models though, especially for slow speed handling. The wings are very thin, working great at high speed. Low and slow is my biggest worry especially with the horizontal stab. They are very happy with the wind tunnel results though so my fears are likely unfounded. Is a 3200rpm propeller a problem with noise/vibration as the tips go supersonic? Why would UL make an engine with such a high possible RPM?
Has a design ever come in underweight? Taking weight out is usually the fight for everyone - even up to airbus! Very clearly optimizing for high speed / long range cruise I think? Be interesting see wing and power loading numbers in these comparisons. One benefit of the higher wing loading might be handling in crosswind / turbulence etc. The kind of flight times these folks are thinking about are long, weather can shift at the destination so a plane that doesn't get blown all over might be nice? Some light sport flyers get nervous (reasonably) when conditions for landing are a bit sideways. Just speculating.
@@randominternet5586 The designers want high speed and high efficiency/range and low cost. Their specific mission is getting from A to B and navigating around bad weather. I'm guessing they plan on airports with multiple runways. They do not plan on lightning protection or deicing, or grass runways, or any other engine besides the UL because their cowling is intentionally limited for aerodynamics. With their process though they should be able to fabricate a modified cowling very easily.
The Jabirus can spin up here too. It gives the opportunity to use a small prop for ground clearance and that won't hurt speed but may hurt TO and ROC. A bit of marketing too perhaps- 200hp from 5.2 liters sounds impressive. That's why I mentioned it may not be spun up this high and therefore won't make 200 hp.
These designs are not popular in North America so of less interest to most of my audience. I'm waiting to see actual numbers from flight tests of Dark Aero before doing any more comparisons. Paper numbers don't mean much unless flight proven.
They are certainly good bouys, doing very good job. One thing I do not understand: Why they put aluminum in between the carbon instead of airex or some similar material? MUCH easier to repair if needed, no corrosion issues at all.
I agree. I also see too many complex machined parts here, especially on the landing gear. Not ideal for production and maintenance. Aluminum engine mount also not a great idea from a fire perspective or fatigue over the long term.
I still cautiously weary of the posted empty weight, especially when the airplane has a retractable landing gear. This tends to increase the empty weight with the pay-off in faster cruising speed from the reduction of the landing gear drag. We shall see what the final numbers will be.
From their recent video they are projecting less than 780 lbs dry for the prototype. I think they did a great job and could still weight optimize some of the design if they want. Though I don't think they need to.
I just run across a number of their videos and am impressed with the overall design processes that goes through their mind. I think that the stall characteristics if they would contemplate putting perhaps some Vortex generators on the wings that would help that smaller Wing be a little bit more effective. I am surprised that the shape is not conducive to closer to about 260 knots. I do think that that engine puts out enough torque that the horsepower number is not the leading criteria. Propellers are pushed through the air and push through water via torque, not horsepower. I don't know why they never print the torque numbers but torque is at least as important if not more so. I don't know why people in Aerospace tend to ignore that number. But that's information for another day. And I know that this is still conceptual. But I think they've got something going here so far. I think that they may get even better performance than they are printing here. Or at least have the clear possibility of doing so. I know that they had toyed with the idea of going with an electric power plant. Which still could be done if they would put a smaller highly reliable fueled engine of some type to run an alternator. Generate ate the electricity that the engine needs to run off of and I think they could cut a little bit of the weight down even further. However I still think that electric Drive will only be viable if it's done in a hybrid manner. Even a small gas turbine engine will put out enough power to be able to even use a battery source and replenish the battery fast enough where you can still have well over an hour of backup when you get to your destination. The nice thing I like about it is you can easily scale up their production Concepts into a six-place aircraft that would be more than capable of being a good Caravan or even light cargo aircraft. The expandability of their build processes seems to be quite nice. I do believe that they may end up going to a center strut to assemble the wings into pieces. It would be easier to replace one or the other should one get damaged rather than having to replace both in case of some sort of damage.
HP, not torque, quantifies rate of work which is what engineers are concerned about for motive use. They know what they are doing. Hybrid drives don't make much engineering sense on aircraft as they operate at continuous high hp unlike automotive applications. Any study will show it just adds dead weight. Watch my vid on Raptor NG which explores the pitfalls of hybrid aviation systems. I don't expect DA will change the wing structure. It would require a massive re-design and re-validation plus add weight and delay production even further.
Where is Peter! Will he hold a seminar at OSH, a booth, take deposits? As much as he failed, he was the hero the community wanted, he was cheered on and raised $2mln from so-called aviation experts. I'm as humbled as he should be for thinking it was a good idea.
Flying out west in the Summer this needs a turbo and more wing to be attractive for my kind of flying. Optimize the design for 12500’ to 17500’ to fly VFR direct at possibly 300ktas+ for 1200 to 1500nm and I can avoid the airlines (weather permitting).
Prove engineering concepts first, then tailor specs to fit specific profiles. High altitude will require oxygen system and should have pressurization. I'm sure these will come in time, but this is the early stage.
The RV 4 with a new wing design might be able to compete on speed. Ultimately I think most builders will prefer aluminium so don’t expect it to sell like hot cakes. Looks very cool though. Would not say no.
These 2 are in a different class with big 6 cylinder engines. Not really comparable in my view and not really available to build any more with most support gone now.
Electrically actuated props have been around since the 1940s and are common on auto conversion like the Subaru. MT and IVO have been making them for over 20 years. in light of this, I didn't think that aspect was worth mentioning.
In the photo of the plane parts at 5:05 you can see the flat front of the fuselage where the engine mounts Does the engine directly bolt to this carbon fibre face? I see four holes and two openings. If so it seems it would be subject to much stress and vibration. Or is there some kind of metal structure the engine mounts upon?
flight directly proportional to situational awareness of pilot...crash will persist throughout all time, simply because you cant pull over to the curb.
This is very light for a 2 seat, 200hp retractable with a C/S prop. This is infusion, bagged and baked. No excess resin. Is there another comparable plane you know of that's lighter?
It is a well thought out design but the addition of blended up wingtip vortex generators is proven to reduce drag, increase lift and improve stability… just saying.
3:05 let's talk about it's stall behavior. (I'll preface this by saying I'm thoroughly impressed with the dark aero teams engineering prowess and attention to detail). Unfortunately, this aircraft is not going to have a friendly stall. No matter what that CFD stream flow shows, that shot is demonstrating a "perfect" steady state stall scenario. The real world is much more dynamic. 1: They use a modern Airfoil designed for favorable pressure gradients for maximum laminar flow. There is no problem with the NLF-0414F and similar foils. The issue lies in the fact that they have narrow drag buckets, therefore one cannot use sufficient washout (wing twist) along the span without causing some portion of the wing to operate outside of the low drag bucket under any and all flight conditions. This would be unacceptable and would likley prevent their high speed aspirations of 275mph on 200hp with 66ft^2 wing area. Therefore one can be assured that the total washout used on this wing was a relatively small amount to maintain efficiency, thereby compromising the stall behavior. (Specifically the roll-damping during the moments after initial stall-break). 2: Taper. The fact that there is a noticeable taper to the wing means the tip will be operating at a reduced Reynolds number to the root, thereby having a reduced maximum stalling angle of attack from this effect alone. They used a moderate amount of taper presumably to avoid adverse effects, bit it's still going to be there simply by the fact that this is a moderately high aspect ratio wing of very small area. Meaning, the wing chord is short (narrow) so it will be operating at a relatively low Reynolds number of only aproximatly 1.5-2e6 at minimum speed. The reason this matters is because Airfoils don't change their stalling angle of attack significantly between Re=3-20million but it changes radically in the range between 3 down to 1 million and below. So even a small reduction in Reynolds number might mean a reduction in stalling angle of attack of 1-2° from wing root to wingtip. This will nearly negate any and all of the slight washout at low speeds and Reynolds numbers. 3: Dynamic. - The rolling motion brought on by the inevitable fact that the stall will nearly always begin on one side before the other will tend to create an un-commanded roll. This roll, as found in all conventional aircraft when stalled, no matter how slight, will cause the wingtip angle of attack to increase due to the wingtip helix-angle. That is, the down-going wingtip sees a relative wind coming from in front of, and below, at a steeper angle than the root at the same fuselage angle of attack. This angle can be significant, and it's determined by the forward speed and the roll rate. An mild wing drop can push the wingtip to a higher angle of attack by several degrees, more deeply stalling the wingtip Airfoil section, reducing it's lift further yet, allowing an even more rapid roll to continue in that direction. (Negative damping, where one needs positive damping). 4: Vertical Tail area and arm. It's a high performance design with a very small tail, for reduced drag. But the vertical tail is quite important for maintaining both yaw stability and lateral (roll) stability in the stall and post-stall region of the flight envelope. Exacerbating this small stabilizer issue is the fact they chose split-flap type rudder control, which is probably less effective than other options due to limited lift attainable and the fact that it will generate a significant amount of drag at full deflection, right when you need maximum rudder and minimum drag, at low speed entering a stall, trying to maintain yaw heading to prevent a spin. [Not to say the split rudder cannot work, it's simply not ideal for this application it would seem. The desire for speed brakes, tricycle gear, and experimental rudder design in an extreme performance design seem to be contradictory requirements in an aircraft, in this pilots opinion. Give it a real rudder, in this specific application. Any pilot worth a grain of salt knows how to slow down with an application of G-loads, overhead break, flatten the prop pitch, etc.]. These issues mentioned are fundamental to all aircraft; But the choice of small wing area, high aspect ratio, moderately high wing loading, especially for the size and Reynolds numbers. And the laminar flow Airfoils need to be placed at nearly the same angle of attack along the span, to achieve low drag, reduces the available range of washout the designers can use. The best option for them would be to sharpen the leading edge of the Airfoil approaching the wing root. This would serve to lower the root stalling angle of attack (though also reduce it's maximum lift attainable by one to several 10ths of CLmax). It would also help maintain laminar flow behind the propeller, having a more aggressive pressure gradient in this area with the sharper nose. They could also use a thicker Airfoil here, as thicker Airfoils with sharp leading edges tent to stall at a slightly lower angle of attack than the normal NLF type foils do. It would also allow more space for fuel, etc. And also improve the width of the low drag bucket. The other alternative is top secret, unfortunately. But it appears the designers have not adequately factored in these problems, or implemented any of the above solutions, by the careful scrutiny of their CAD models and prototype wing they did not use a sharper leading edge or thicker root Airfoil section, nor did they use any of the more common solutions such as significant washout, discontinus leading edge, droops, cuffs, VGs, etc. And so this issue will certainly become a problem that will inevitably limit the market audience for this model and place it among the other high performance oriented (read compromised usability) types.
Much needs to be proven and validated in the flying prototype for sure and I've been clear about that in my comments. Certain things will not work out and have to be changed in production kits. You never know on stall characteristics. The Questair Venture has a very small chord, highly tapered, thin wing but has reasonable stall characteristics. I was involved with one of these at Reno in 2008-2010 where it won Super Sport Gold there. Neat design that not many people are familiar with.
@@rv6ejguy that Questair Venture is a fantastic design, I researched it several years ago, and was keenly interested specifically in it's stalling characteristics, believe it or not. (There is a video of one stalled on short final, you can make out the wingtip vortexes, and it takes a good two-count to begin a roll off to the side, it impacts mostly level). So, it has excellent post-stall roll damping. That aircraft was created by a top civilian aircraft designer and utilized much of his experience from the Piper Malibu, from my internet research of the plane, and the fact it appears to share several components. Especially panel-forward. Stall behavior is actually very predictable, Ddspite what all the textbooks say. As there was a massive amount of research in the early to mid 1940s by the NACA. Incidentally, the Venture uses an Airfoil combination that I myself had selected as a good stalling combination based on some of those research papers. The F8F bearcat uses virtually the same combination. It's known to be rather docile when power-off, based on reports of the era and not recent hype. The Beechcraft Bonanza also utilizes the same Airfoil series, and very similar Airfoil section thickneses as the Bearcat, Hellcat, and Questair Venture. The 23017 stalls quite gently, with a soft peak and some post-stall lift. The 23012 is far more abrupt, and drops off sharply under most cases. Probably the worst-stalling airfoil ever made is the 23009, which is found at the Bearcats wingtip and the 23010, only marginally better was used at the tip in the questair venture. - But, it all works because the 23012-23013 section thicknesses attains the maximum lift of that Airfoil family. (13% attains maximum lift across almost all Airfoils, laminar and turbulent). And the 23012 appears at aproximatly the 70-80% semi-span of the Venture (and the Bearcat). So, the the root is a soft stalling Airfoil that stalls at a lower CLmax than the 23012, as the 23012 has an identical, or slightly steeper lift curve slope, the same zero lift angle, and attains the highest CLmax, staining a higher AoA than any of the other thickneses of that Airfoil fanily. By using a normal wing taper ratio, with 17% root, 10% tip airfoils, the 12-13% thickness sections fall at the 70-80% semi-span of the wing, instead of being too far inboard to provide adequate roll damping. Or too far outboard to make any lift at all (Bonanza wasted the 23012 at the tip, where zero lift can be made, should have used the 23010 or 11 to move the 12% inboard a little). so, The 75% semi-span of the wing on the Bearcat, and the Venture remains flying, after the gentle root stall, and doesn't roll-off immediately unless pulled aproximatly 0.5°-1.0° farther into the stall. The 70% semi-span has a longer chord, and therefore higher Reynolds number than the wingtip, and suffers less adverse effects because of this. Placing the highest lift Airfoil outboard far enough to provide roll damping, but inboard enough not to suffer much Reynolds number effects, then adding any amount of washout twist will increase this stall margin. The Venture stalling characteristics were absolutely known to the designer in the preliminary phase on that specific airplane, I know it without a doubt, as well as the bearcat, which was intended to be a maximum performance fighter that needed to land on carriers by 300hr pilots. Good stalling behavior are almost never an accident, except in the case of 1910-30s constant chord wings made for simplicity ended up being good, almost by accident. The Dark Aero, I can say is going to have a rather small margin between root and tip stall, and therefore won't have much roll damping in a post-stall condition. This is because those few Catalog NLF Airfoils that have an identical shape to the one they have selected have a small low-drag "bucket" and this limits the amount of washout that can be used, as I mentioned previously, and it appears by their CFD results that washout is their method of choice, and not a combination of the above thickness variations, along with variation in leading edge radius and section thickness that it would require to make it exceptionally stable in the stall. So, I foresee some owners applying VGs in front of the ailerons, which will cost drag and speed to die disruption of the laminar flow in that area. They can also add a stall strip to the leading edge at the wing root, which won't cost any drag measurable, or maybe use some other bandaid fix. But, it's inevitable. Imo. - If there were a thicker section at the root, or a variation in the leading edge radius along the span, growing thicker to the tip, or if there was a very distinctive root stall on their CFD screenshots, where the tip was decidedly not-stalled. Then I would not have made any negetive predictions. But the design, by my scrutiny, lacks most of these features, utilizes wing twist exclusively, which is limited in it's amount by the low drag range of the Airfoil selected. And that angle variation will barely, if at all, make up for the variation in stalling AoA, due to the significant Reynolds number effect in that very low Re range of 1.5-2million. There is actually a brilliant way I've sort of re-discovered, to provide post-stall roll damping at any attitude, including inverted, and almost any airspeed, any reasonable, or even unresonable sideslip angle. But it's in conflict with achieving laminar flow at the wingtips. Many designs have used it since 1935, but most it's a side effect of other design considerations. There was one WWII fighter, an earlier design which was used throughout the war which had such fantastic stall characteristics that it could be pulled into a stall and flown around in that condition without snapping, or dropping a wing. It had a billiant designer, who was so far ahead of his time that almost nobody seems to have noticed, and 85 years later people still consider stalls to be difficult to tame or predict, when it's actually a very easy matter if understood completely.
Might vortex generators help tame that stall speed? They seem to do remarkable work on other designs, without noticeably harming high-speed performance,
We'll have to see what the actual stall speed is after flight testing. Small wing = high stall speed, all things being equal. I can't see these guys adding VGs to this design. In any case, 70 mph is no big deal, just fly it by the numbers.
I quit watching these guys after the Raptor fiasco started to get silly. Now I’ve caught up on a years worth of videos. The problem for those of us who initially thought the Raptor was going to happen is that we are all looking for a 4 seater. That said, these bros are very likely going to be a force within the industry and I suspect a four place will come very soon after this model is on the market.
I suspect that they might have some issues with the method they’re use to actuate the ailerons, might have too little stiffness given the tube design actuate by torsion.
The only thing I don't like about the dark aero is the split tail. I also wonder if the new ul520ist will fit. The idea of a normalized motor is intresting. Its ~30 # increase in weight. It does have a ~5 " bigger x dimension. Not sure if it would fit, but it is intresting.
I am open to seeing if the split rudder works well or not. If it works, bravo and you have a speedbrake of sorts too. If not, back to a conventional rudder and lesson learned.
After review of more of Dark Aero videos (or re-review after last watching a few of them almost a year ago) a few things still bother me as I state below. $80K kit price, with engine and prop they claim it will be $140-$160K. Second, UL520Si engine can only accept fixed pitch or electrical props, not hydraulic. Price of engine could not be easily found, but I am willing to bet it is more than a Lycoming. Also at 320 cubic inch displacement and claimed 200 hp I doubt, unless it is geared high RPM. They say it is direct drive? Some of the smaller UL engines are not getting good reviews. Satisfaction from owners is low, with 400 hr TBO, poor support, failing parts both mechanical and electrical. My biggest concern with this project is choosing a relatively new exotic UL engine and not a tried and true Lycoming. Yes I know UL is MODERN? Kidding. It is still a 4 stroke pushrod overhead valve air cooled engine like a Lycoming. *The Lycoming 320/340/360/390/540 engines are specific built aircraft engines with the best materials and optimal design honed over a half century, which benefited from massive WWII engine R & D and experience in design, materials and manufacturing methods. You really can't improve on perfection To me the other option is Continental. A "modern" FADEC or EFI can be installed on Lyc. In experimental or certified planes you can retrofit a single or dual Electronic Ignition on Lycoming engines. Still mechanical fuel systems and magnetos work very well in planes... modern or not it works well and always will, reliable, simple, electrical system independent, with good efficiency,. "Modern" claims are irrelevant. As far as the mechanical part of the engine the Lycoming is a real engine, overbuilt and stout. The UL looks like a toy or prototype with CNC machined parts. It may be fine for a low powered LSA but not high altitude aircraft with what I am guessing will NOT have low stall speed. The claim of 200 HP in normally asperated 320Ci engine I doubt.*
In one of their video's they went over pricing of the engine and prop. I don't recall the price of the prop, but the engine is in the $30-40k range depending on options, theirs was in the $35k ballpark if memory serves.
As I stated in the video, it's direct drive and 200hp is developed at 3300 rpm. I said hp will be closer to 185@2800 rpm which I feel is more realistic with the prop size they are using. Electric props have been around for many decades and work just fine for this application. Curtiss electric props were built by the 100s of thousands for many WW2 aircraft. I have lots of customers flying electric props. Work just fine as long a you're not doing aerobatics. The Lycoming is too heavy and too big for this lightweight design.
@@rv6ejguy As always your videos and posts (and products) are very comprehensive, technical, well research, accurate, and explained very well. I did not mean to imply you did not cover the UL engine HP/RPM. However I echoed and added my concerns. My opinion is the UL engine will not be durable, not perform as claimed, not be supported by manufacture. *Electric props?* YUCK! Ha ha. Yes they have been around a long time and problem plagued for as long as they have been around, going back to WWII, when developed and used widely on military planes. C-46 Curtus Commando accidents due to prop issues come to mind. It was so bad pilots refused to fly and the C-46 got the reputation as a widowmaker, due to props going flat pitch on takeoff. *Hydraulic props are better with the exception of Raptor. Peter should have gone electric.* Not saying electric prop pitch control isn't a viable option, just a poor second choice in my opinion. Again "modern" doesn't trump tried true technology that works, aka hydraulic CS props. Why are hydraulic props used on all serious piston and turbo-prop aircraft? The reason is it's superior. My point the Dark Aero's lack of engine prop options (i.e., Lyc + Hartzell) makes it a pass for me and doubt longterm success. I'm not a luddite just realistic. Also my RV7 Lyc 180hp Hartzell is a better plane overall, for me. I think the Dark Aero would be much better with a Lyc or TCM. PS if they want to succeed and a Lyc will not fit and not willing to change design, an alternate option to consider, is the Rotax 915 iS. I don't like Rotax or water cooling, but it is certified, supported, with fairly large fleet and known history. Air/Oil cooling of is my preference over the Rotax water cooling. The Rotax continuous max 141HP is available at higher altitudes with turbo, giving it an edge over UL for high altitude operations. I see Dark Aero as a cross country machine, NOT a sport plane, STOL, soft-field, aerobatics and utility. Another engune option is Continental IO-200 it would be slower on 110 HP but very efficient and pretty sure it would fit. This was the original of Lancair 200 it used a O-200 Continental and fixed wood prop. Light, cost effective and FAAAST. Builders on a budget could source a used O-200. With a light fixed prop it would be a delight to fly I imagine. Low weight and low complexity and low cost. I still would not buy or fly a Dark Aeto with UL or Rotax. For that money I could buy a flying used Glassair or Lancair.
@@gmcjetpilot I'm willing to try something new. A big focus is trying new designs and materials and seeing if big performance gains can be had. A non certified engine makes the most sense to push the envelope. If the DarkAero UL fleet doesn't end up being reliable, I'm sure the next iterations will feature different engine options, among other refinements.
@@Zav OK up to you. You want a nice flying plane or something new. This airplane will miss it's speed range mark, be very expensive, take long runways, not be aerobatic.... If I wanted a plane like this I would by a flying Lancair 360, Lancair Legacy, Glasair II or Glasair III already flying for less than what it would take to build this plane. BTW the kid does not exist yet.
Maybe I’m misunderstanding but their estimate for useful load is 750 lbs and your estimate is 680, with full fuel that drops to 280 with their numbers or 220 with your numbers. I’m 230 lbs. I guess this isn’t the plane for me..
Imagine someone who is 150-180lbs in this thing :) Might be a plane for the young. That said, do you really need the range they offer? Could trade that to jump in.
I have seen the hull at Oshkosh and this plane's appearance is more like a big model airplane than something you can get into and sit comfortable in. The cockpit is a big shallow shoebox. It's definitely made for slim people. But it will be fast and the fit and finish is amazing!
Yes, the cockpit looks pretty cozy for big guys and payload with 460 pounds of people and 30 pounds of baggage drops to 32 gallons. That's what RV-14s are for. It will carry this with a bigger cockpit and still allow for full fuel.
I don't see any correlation between the wing area and the initial climb performance. Sea level climb performance is the function of the power (trust), weight and L/D ratio. Thats it! Please consider these facts in your future videos. Despite this your videos are quite good and gives me huge relief when see numb project are totally roasted by real engineering aspects.
I think you'll find in the real world that most aircraft with high wing loadings and low power don't climb very well. Lift to drag ratio is important with lift being the numerator. Small area at low speed means low lift unless you increase AOA-which results in more drag. If you have high power and can go faster in the climb with that small wing at a lower AOA, you can climb ok. The drawback is speed varies as the cube of the hp so you need a lot more power to get that speed to make the small wing produce excess lift for a good ROC. We shall see how DA1 does here when it flies.
Just have to fly it by the numbers. I don't think they'll be adding VGs on this design as they are trying to maintain as much laminar flow as possible.
Small, fast wing... great on paper but- well, Lancair has gone that route before. Stall, climb, slow flight/wing loading issues- if shit hits the fan repeatedly with this thing- like happens with these types of planes, no insurance company will pick up the phone- and it's dead in the water again for the extreme fast kit plane world. There's a reason Lancair's are selling for a fraction of what they're probably worth on paper- nobody can get them insured.
Great Video Ross! Hats off to Dark Aero. These young men are very impressive, but be wary of a new airplane, a new engine engine and a new (electric) propeller. Way too much simultaneous testing for my tastes.
Nice looking, just like Lancair. If they can keep cost down great. A $100k kit, it won't sell. 6:25 Firewall in single Eng plane is great but a gas oil fire in flight will be a bad day regardless of FW. unless cowl is also fire resistant with active fire suppression. 6:51 UL choice of engine not my preference. TBO? How many engines flying & total fleet hours? Certified? Issues? (Yes) Light weight = light duty less strength? They should have sized airframe for a Lyc. They will regret this choice. *What is "modern" about UL engine vs Lyc? Lyc & FADEC? Available. Electronic FI and IGN available for Lyc. Machined billet case better than precision castings? No. It is just easier to CNC a case without huge investment and special manufacturing in castings (a lost art). UL in business 15 years, throwing all your eggs in one engine basket is risky, especially a small engine company whose Lyc killer engine models are fairly new or still being developed. There has been UL issues. I'm 100% in identifying this potential risk in power plant. Lyc is a known.. and still around because it is a good engine.*
What are the options for Lyc & FADEC? You can absolutely buy an EFI for Lycoming (from this video creator!) and I'm considering doing just that, but FADEC? On what experimental Lyc engine can you get one of those, and from where?
@@rv6ejguy Pipistrel had an initial problem with one of their aircraft’s tail tube breaking due to pilot error, not understanding the IAS TAS relationship and exceeding Vne at altitude. Not sure if the fuselage was strengthened where it thins down near the tail feathers. Fortunately that aircraft had a ballistic shute and the pilot survived to tell the story. Not, repeat not, suggesting there’s an issue with the Dark aircraft!
@@daisybeagle6259 I'd hope professional test pilots and engineers all understand the IAS/TAS relationship with regards to flutter at altitude. The Pipistrel has a very narrow section fuselage aft which isn't ideal with regards to stiffness, especially in torsion. Always things to learn during flight testing and dive testing is one of the most dangerous aspects of that. Hope DA has an experienced test pilot doing this part and has the airplane well instrumented. I'd hope they also do GVT before flying it too. A bit expensive but probably well worth it to uncovered possible flutter modes early on in a safe environment. Thanks for commenting.
Mass producability is a factor often overlooked by amateur aircraft designers. The aircraft may fly great but is too labor intensive to go into production. Many designs have died because of it.
I agree and I think this has been carefully considered here, mainly in the use of CNC machines to produce a lot of the parts which would traditionally be hand made. Machines can make parts better, faster and cheaper than human hands in most cases. If we look at something like Raptor with a very numerous parts count of complicated parts, we see that it can't be made inexpensively as it sits now. That aircraft would require numerous components re-designs to simplify it for production, on top of a structural re-design and engine change to reduce weight to something acceptable.
They have been making sure that the parts they design are as easy as possible to manufacture, so I'm not entirely sure why you thing it's going to be too labor intensive.
