Said it before and I'll say it again: I'm not a pilot and will never be able to afford my own aircraft, but damn I love seeing the engineering approach in these videos. Wishing DarkAero every success.
I am with you bro. I can afford an aircraft, but the minister for finance and war says NO. I shall simply enjoy watching videos by engineers who are doing brilliant work.
I appreciate the CAD walk through. It makes daunting and complex looking system design seem much more approachable when you can break down how the final result was achieved.
You guys are incredible. It is so fine to see an aircraft being designed by professionals instead of enthusiasts. I hope this aircraft is an absolute success for you brothers. Well done.
22 seconds in and I’m upvoting because of the amazing humility and focus on quality, safer, and innovation you have explicated in that short amount of time. And because, as a self-taught journalist with a decade’s experience as the tech editor of a CAD industry trade magazine, I must highlight that you got the most important bits above the fold.
Awesome as ever! Nice to finally see a video where the creator accept they got something not quite right and then showed how they fixed it. All too rare in the RU-vid world. Well done guys and keep it up, this is awesome stuff! 💪🏻
I'd think you'd want the fuel return lines going to each wing tank and not the sump to keep the entire system properly pressurized and not get back-pressure on the feed check valves causing vapor lock. *You also want to install an air return line into the highest point of the sump to the highest point of the wing tanks should air be introduced into it during maneuvers. The sump could use a baffle across the center with a hole for crossing. But I think the shape you created for better contamination tests accomplishes this fine. I'd do the math to see how long the fuel in the sump alone would last under climb and cruise power to see if the sump is large enough to carry you should you encounter any feed issues. Wouldn't hurt to double the feed lines to the sump in that regard. I forget the wing tank layout and whether you baffled the pre sump feed area but that would be a good idea to prevent air entering the sump area. *I think because the sump is not large (I know you all are working with constraints) the fuel will start moving rather quickly there and air could be introduced if not properly accounted for. It also needs somewhere to go if it does.* Now to discuss my consultation fee...
I’d throw in a pressurized surge tank between the sump and the engine. I’d also make the engine fuel delivery a return-less system with a pickup pump moving fuel from the sump to the surge tank and then have the main fuel pumps housed in the surge tank. This surge tank would have return fuel system to deliver excess pressure back to the sump or main tanks. (How you build a high-g fuel system for a high HP drift or drag car)
Another reason wings are good for fuel storage is because the wing itself supports (and distributes) the weight of the fuel, and you don't need additional structure in the airframe to support the weight of a fuselage tank. Smaller, lighter spar, smaller lighter spar support structure.
Every video y’all put out is fascinating within itself. I’m so excited for your whole team. This isn’t just another neat airplane being built. The tech and foresight your team is using will advance the aviation industry by leaps, not steps.
I've finished university and had children and they still didn't finish it . I'll put my RU-vid account in my kid's name in hopes they will see this plane fly before global warming melts it
@@zorintoto1167 Haha, takes a long time to both develop and make production molds for an aircraft like this. But yeh, I've been following them for years as well. Still wanting to see it fly though ;)
Great work guys! Have you considered fuel heating when recirculating back into a tiny volume at high flow rate? Might be better to recirculate into the high volume main tank which is "aircooled". I see that you are trying to solve the fuel selector problem as a source of potential pilot error and nuisance. Would it not be simpler and more controllable to replace a clasic fuel selector valve with 2 solenoid shut off valves (with manual override) that are automatically controlled by digital fuel level sensing? It would also solve the following threats: 1)One tank becoming unusable fuel due to a stuck check valve. 2)The higher tank feeding alone (side slip) causing an imbalance that makes the low wing even heavier and the high wing lighter. 3)Inability to isolate one tank if deemed necessary. With computer controlled balancing you could run different regimes 1) automatic balancing based on measured quantity (you could even program a deliberate imbalance e.g Keeping 30pound more in the right tank to minimise control deflection with single pilot ops). 2) Automatic switching after elapsed time (if fuel aensing fails) 3) both at once 4) manual operation as back up. Sorry, I can't shut up. Keep doing, what you're doing, you're doing great.
Simplifying the design to eliminate the fuel selector is a good step. Fuel mismanagement has been a major cause of accidents. Design to minimize fuel transfer is good. Simple ball check valves that allow some leakage between tanks might be reliable enough to work without complex computer control. Trimming one wing slightly high or low for balance issues might work without adding complexity. The ideal I think is the Cessna 150-2 fuel system, several European Manufacturas's also have good fuel system design for their planes.
Another master class in aeronautical engineering, design & fabrication! Your team is well placed to teach engineering design at colleges & universities.
Been sharing some of your videos with my local engineering team members! Thanks for sharing about how DarkAero follows Engineering process and some of your innovation! Love the video format and communication, so easy to follow and fun to understand.
Excellent! I see two considerations not mentioned in the video: Static electricity (Electrical bonding of components and structures) and provisions for thermal expansion of fuel and potential leakage at overboard vent ports. A lightning strike would be worst-case, but static can occur in places you may not expect to find a difference in charges. If using high octane fuel this is especially important.
Quality work gentlemen! It would be interesting to see tesla valves integrated into your wing and sump tank to reduce slosh and wing to wing transfer. Keep up the good work team!
I know it's not part of the scope of this design, but one thing I hope becomes a thing in small aircraft design is a battery backup system for aircraft engines that can drive the prop for a minute or so, such that pilots have time to land in case of engine failure. You guys' commitment to safety is extremely effective wrt the resources available to you, though. The redesign of the sump tank is brilliant.
I love your videos! I am a sport pilot working on my PPL I own a REMOS G3 all composite Light Sport aircraft. I love seeing your iterations and adjustments while it must be frustrating for you it shows your drive to get it right. I actually reached out to Aeropro to potentially buy their molds and specs for their project "Vison" ..... 6 Mill Euros lol meeting with a couple investor groups before I go out and look.
With such brilliant engineers and innovators like you guys ... watching this evolution is not just a pleasure but a blessing. People don't understand iterative development ... and how EARLIER thought contibutes to future mods. I mean the videos you put out ...are ... i don't have words ... ♥♥♥♥ It is INDEED a Dark Arrow in the world of innovative airplane design ... you don't see it ... but it's there and coming in strong!
Would love to kow how do you collaborate with your test pilot. How does their input and prespective shape aircraft development, design and building in your case. Great video as always 👍
Nice design improvement. You're generously transparent about the design process. Do you have additional drain ports in the wing tanks? The reason I ask, is because if any part of either wing tank sits lower than the wing-tank outlets, then it might be possible for water/contaminants to collect in areas that aren't drainable while parked.
@darkarrow Yeah what about this question? I don’t know if foam is needed but what about g-loads & pitch angles? Were those tested? What about delta ram air pressure in tanks during an extended corkscrew or something? My high wing only uses one vent so just thinking/questioning out loud. ….
I am egregiously pleased with myself for having identified the salient problem in your excellent introduction to the design of the first sump and the conditions expected of its placement. Then, I imagined how I would have “fixed“ it, and I was essentially correct! _Hooray for me, I´m an aviation engineer!_
Soooooo glad you guys are taking the time to design “good testing rigs” and redesign the potential problems way before a customer encounters them. Textron doesn’t even put this much thought into their products, they just wait for customers to hit the ground then say oh, I guess we need to put more effort into that dumb flawed idea.
This is a great example of the engineering design iteration process. Think about it, convince yourself that it is amazing, build it, test it, realize that it is not really amazing.....reapeat until the result is amazing.
Do you realize how much money you could make turning several of these 15 minute videos and curating them into a playlist or curriculum for flight schools, Air Force training guides, engineering and physics courses and just all sorts of other schools, colleges, universities and other educational platforms all over the world! Literally 10x what you’ll make selling the plane. Edit: I started writing this before the 10min mark where he mentions they do have an internal course. But my point still stands it’s just even easier because there’s already a product in the one course.
Not having a fuel selector is a mistake. You want a way to turn off fuel to a specific tank in an emergency. It is barely any pilot workload you are adding, let the G3X manage alerts.
Great informative video. Did you already explain your design around the Vent Shuttle Valve somewhere? Would be interesting to understand that details of that. I favour you decision to do away with manual tank selection, but I'd also like to understand how the tanks will ballance statically and dynamically (During fueling, on the ground and in the air).
How do you deal with high roll speeds pulling fuel away from the sump? Similar with low G/ inverted maneuvers? I can see how the check valves in the sump have a good chance of keeping enough fuel in it during high speed rolls from starving the engine though. (Correct me if I'm wrong in thinking you need this as my understanding is this is a high performance/show aircraft or if the aircraft is not being designed with these maneuvers in mind) These videos are very interesting and have helped respark my love for engineering. I cant wait to see this project finished
You guys seem to be on your way to be a younger version of the Patey brothers. Great work! Take care and don`t forget to make sure your hat still fits. lol
And why not weld together a conventional alu tank, it can't be any significant difference in weight. I love the obsession with perfection, but... aluminum is a conventional choice for fuel tanks... for a reason. But, they've addressed the resin question before... the wet wing uses a special resin that is impervious to the fuel. Still... carbon fiber parts aren't wet proof. Aluminum is the perfect material for this...
@@williamhoffman4337 No , but that engine runs on Mogas as well as the highly leaded Avgas100. Loads of microlights have had their tanks go soft with resin destroyed. Thank goodness they don’t have 130 leaded avgas now.
My plane’s two fuel tanks have… Screens at the fuel pick-ups in the tanks… Sumps lower than the fuel pick-ups… Small dead space in the lower corner of each tank, because limitations in aluminum construction… Another screen at the bottom of the fuel separator below where the two fuel tank lines feed the separator… Tiny screens in front of each fuel injector… Each fuel pick-up is at the back of the tank… so it is sure to pick up fuel when the nose is high on departure… The pick-ups are at the inboard end of the tank… so it is sure to pick up fuel from the uphill wing during a slip to final… Fuel cap seals have been updated to be blue fluoropolymer seals to keep them from absorbing 100LL and changing shape over time… Tank vents are at the top corner of the up hill end of the tank, with a hose venting to the bottom wing surface… have a method to pre-flight for bugs… Things to consider when designing new fuel tanks…. 😃 (from a Mooney driver)
If/when the energy density of batteries approaches that of liquid fuel, would all of this fuel management engineering become obsolete? Do you secretly pine for the day this happens? Or is that a pipe dream?
In Europe(I guess Italy) they make the ultrafast two seat aircraft called Risen. Please note, with 100hp Rotax they guarantee the top speed at sea level 320km/h (173knots) and with turbocharged Rotax 915 -142hp they guarantee maximum cruising speed at 16 thousands feet 450km/h !!! (243 knots ) !!! Will Dark Aero be able to achieve the same velocity with much stronger engine ??? Risen has got the ultimate aerodinamics IMHO. Extreemly efficient and it is all carbon fiber too. What I like about Risen compare to Dark Aero, that Risen is not using any metal(aluminum) honeycomb, but rather materials which can never ever rust.... On the other hand what I like about Dark Aero is the gear(looks strong) and the 2 baggage compartments.
@@FatDickDanny On the top of that speed it has extreemly long legs too...it is the only ultralight which flew from Europe to South America directly, using just regular tanks.(Europe-Arica- South America)
Fun fact, aero engineering is the origin of "one of," as in the engineer draws something and sends it to the shop with instruction to make one *of* these to see if it'll fit. It's mildly obsolete given CAD but it has a certain charm.
It's always good when bug-fixing lets you simplicate and (probably) add lightness as a side-effect. Are the fuel tank vents out at the wingtips? how do you sstop them from siphoning if the machine is parked leaning? (On uneven ground.)
Love every single update you guys out out. Your engineering and attention to detail is spot on, as it should be considering you're building a machine that's going to fly through the air at over 150 kts. Can't wait to see this thing take to the air!
You guys chose to go against a fuel selector valve & said you were sure the fuel transfer rate was within acceptable margins, could you expand on that? Does this design mean that if one tank has a higher head pressure than the other, it will flow into the sump faster, automatically balancing the tank levels?
I’m not sure I understand the purpose of having the sump tank. On my rv7 I just have the 2 wing tanks go into a single line and the a transfer line going side to side for fuel transfer. There is a selector switch like mentioned in the video but I always leave it on both. The diamond da40 work’s interesting as well where fuel is only pulled from the right wing and then the pilot has to turn on a transfer pump to pump fuel from the left wing over to the right wing.. this sump tank also appears it would create air in the fuel lines if flown inverted. Love the project!
It seems like going with a fuel selector could still be better than this. Most pilots are used to switching tanks and I think I would trust myself more doing that than a bunch of valves and piping and tanks, etc. Even if you run a tank dry, the engine slowly starts sputtering, switch tank and it comes right back to life.
Fantastic presentation and discussion on the development of your fuel system to power the engine in Dark Arrow 1 Takeaways * Fuel storage and its effect on the centre of gravity. * Benefits of a sump. * Composite carbon fibre moulding. * Petroleum and fibreglass * Gravity and electric pump delivery systems. 🌏🇭🇲
I'm more concerned about the weight of a full wing when the other one is empty. Could it tip over the plane given the well understood tricycle wheel arrangement.
@@blakeg9221 that's a good point. A crossover line could keep the thanks relatively level but then you'd have large quantities of fuel transfering during manuevers.
"What happens when a design fails?" It ALWAYS costs a LOT of money and sometimes people die. Having spent 25 years designing and managing the Engineering design of products I evolved several design rules. 1. NEVER, EVER let an "industrial designer" DESIGN products. STYLE yes, DESIGN NEVER. 2. ALWAYS have a Design ENGINEER design products. A Design ENGINEER MUST HAVE knowledge of all the production parameters of all the production processors required to make all the component parts of his design. Industrial Designers are concerned with the aesthetics of a product and some hapless Production Engineer is left to sort out their mess. My design rules for my Design Engineers were : 1. Design the assembly to last forever - amen. 2. No failures permitted - whatsoever. 3. No adjustment both on assembly or in the field permitted - whatsoever. 4. Absolute minimum of fasteners permitted WHICH MUST BE IDENTICAL TO EACH OTHER. 5. Top down assembly 6. Poka Yoke for assembly - physically impossible to assemble a part incorrectly. 7. Absolute minimum number of parts in ALL assemblies
The problem is this is an experimental aircraft that has never flown. If for some reason the main gear had to be moved 2" it would require redesigning everything adjacent and could add months to the design. That includes every subsystem, the nose gear, the canopy mechanism, etc. This plane is also pushing the performance envelope. Who is going to test fly it?
Great question! Kevlar (aramid) fiber would work too. Glass fiber is a little easier to work with, but aramid is lighter. It all depends on your design goals.
