BIG Spinner for LOW Drag? | Carbon Fiber Spinner Design & Install on the DarkAero 1!
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- Опубліковано 29 чер 2024
- Learn how to make your own high-quality carbon fiber parts: darkaero.com/courses
We finished installing the carbon fiber spinner for the DarkAero 1 prototype on the Airmaster propeller hub. The spinner was designed in Onshape cloud CAD.
The mold for the forward spinner bulkhead was CNC cut from MDF on our AVID CNC router. The mold was coated with mold release and then we were able to make the forward spinner bulkhead from carbon fiber using a vacuum resin infusion process. Holes for the blades were cut in the spinner using a Milwaukee oscillating cutting tool.
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Sanding
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Safety Gear
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A new aft bulkhead was also infusion molded and the bolt circle pattern was cut on our CNC router to ensure the pattern was accurately located. With the new parts fabricated, we were able to assemble everything. We used Click Bond nut plates and countersunk screws to hold everything together.
The spinner on the DarkAero is larger than what is typically found on light aircraft. This was done for aerodynamic reasons. The larger spinner allowed us to make a more streamlined shape for the nose and cowling of the airplane. Ideally, the nose of an airplane would be shaped like a torpedo or teardrop for aerodynamics. However, attaching an engine and propeller to the front of the airplane forces the shape to deviate from the aerodynamic ideal. The most popular light aircraft engines are air cooled and use a horizontally opposed piston configuration. These engines are typically pretty wide and the cowlings that are built to enclose them also end up being wide and somewhat square shaped, especially if a small spinner is used. The 200hp UL Power UL520iS engine we selected for the DarkAero 1 is about four inches narrower than conventional airplane engines, which helped us create nose geometry closer to the ideal shape. With the cowling designed around a large spinner, it was possible to make a smoother geometry transition from the spinner to the cowling, which helps reduce aerodynamic drag.
The drawback of using a larger spinner is overcoming potential imbalance issues. The propeller and spinner need to be dynamically balanced. The rotating mass of the prop and spinner needs to be evenly distributed around the rotational axis, otherwise there would be vibration. Vibration is bad for the aircraft and uncomfortable for the pilot. Balance with a small spinner is dominated by the propeller but with a larger spinner, the balance of the spinner itself comes into play.
We tried to minimize inherent vibration in our spinner be eliminating any asymmetric seams in the part that would create localized heavy spots. Our spinner design is comprised of two sections; forward and aft. Each section is molded using continuous layers of cloth rather than spliced cloth segments.
With the spinner finished and assembled, we powered up the Airmaster propeller controller and actuated the propeller blades through their full range of motion to check clearance between the spinner and the blades.
Next, we will be attaching the engine to the firewall to complete the remaining firewall forward tasks.
If you enjoyed this video and would like to see more of this type of content, follow along as we work to engineer the fastest, longest range aircraft you can build in your garage!
More information on DarkAero can be found on our website and other social media accounts:
DarkAero 1 Aircraft - www.darkaero.com/aircraft
DarkAero Knowledge Base - www.darkaero.com/knowledge
DarkAero Apparel - www.darkaero.com/shop
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Video Chapters
0:00 - Intro
0:38 - Spinner CAD
1:07 - Finishing the Spinner
2:51 - Why so BIG?
5:14 - Spinner Balance
8:02 - Reducing Imbalance
8:53 - Moving the Blades
10:45 - Next Steps
Thank you for watching! - Наука та технологія
When engineering approaches art.
Don't know if I want it just to look at it, or to fly it around.
Towards the end of the video, the breif view you showed of the aircraft front, with engine, prop and partial cowling installed, was exciting.
More to come on that project! 😁🤙🏼
@@DarkAeroInc Looks extremely good!!
I can't say enough about how impressed I am with the work you guys are doing on this project. I just wish I had been in a position to make a deposit back when you had the intro pricing. I'm building a Kitfox now, but I could definitely see a DarkAero in my future. Thanks for all the great video coverage. P.S. I dig the COVID mullet!
Waited in line all night for the release of this video...it did not disappoint. Keep up the great work guys!
This is the precise reason why I fkn love aeronautical engineering, watching these kind of design procedures and engineering information goes directly to my soul. Keep up the good work!
I'm becoming quite enthralled with this channel. The clear, concise explanations are fantastic. I'm learning and relearning many things. Especially enjoy the (edit: opportunity) cost benefit breakdowns.
The level of precision and attention to detail is breathtaking. Well done DarkAero! Can't wait for the kit.
She's a beauty gent's. Well done
Really appreciate the detailed explanation of your design decisions.
Keep it up, very exciting!
That spinner looks sick, great job! Can't wait to see the engine start. Ciao, Marco.
I am completely captivated by this build! Sign me up for the first four seater DarkAero!!! (Might have to sign-up for DarkAero1 as well...)
Sorry the first 4 seater is already spoken for. I have it claimed. You can get the second one :-). I’ve been asking for the 4 seater since they started! Haaha
Very cool discussion of strategy to maintain balance in the spinner.
I'm assuming the mass of the quickbond nut plates is really consistent. That's another plus for a design like yours in addition to being quick and convenient.
Detailed engineering + precision built + beautiful lines = flying perfection!
This plane is so beautiful and well designed, I might have to build a DarkAero after I am done with my RV-10! Can't wait for your test flights.
Terrific stuff, lads.
big beautiful spinner. keep an eye on it.
Nice! Keep the updates coming!
Great video. As you were describing your approach on this I was thinking "sounds good but that can create some serious issues". Then, as the video progressed you addressed all of those issues in convincing fashion. I looks like you are going to end up with a real airplane.
Nice spinner. The large spinner may also help keep a high pressure area at or near the cowl inlets. I imagine performing a dynamic balancing of the spinner/bulkheads assembly might be beneficial.
Breathtaking, such a detailed explanation every time you brothers say something about Dark Aero. I wait for new episodes on Dark Aero.
UA-cam and carbon fiber, what would we do without them? Amazing work guys on both fronts 👍🇦🇺
Great analysis!!
Looking great guys!
Nice guys! That is a huge spinner!
Thank you! Your question on our earlier propeller video served as inspiration for much of the discussion in this video!
That prop changes pitch much quicker than my MT prop. I like it.
WOW that looks very nice :)
I have been watching the progress of DARK AERO for a while now, and your workmanship is superb! Your explanations of the technical aspects and conditions are very interesting and incisive I can't wait to see First engine start and first flight. Have you done any wind tunnel testing or is it all in the computer ?
Great explanation!
Superb job guys, as usuall !!!
Looks beautiful guys! I'm curious how y'all manage carbon dust when cutting it with that oscillating tool. Wanna make sure y'all are around a long time!
our windmill had a big hub , local guy came to balance it, luckily it has 12 provisions to add a screw and weights, done see any on that hub.
Feather is often used right after startup on a lot of commercial planes, to make sure they don't move when on the stand. This will decrease stress on the brakes when they don't need to be used.
Hey guys, I love how the spinner looks! I know you said you don’t have a clear number for how much efficiency increase with the larger spinner, but if you can work out ballpark that will be great. If the gain is small would it be worth it to have a more expensive custom part with additional balancing effort (vs cheaper more common off the shelf)
legit
Thanks Fab Forums! :)
looks like the spinner on the ME. 109
Need to paint a big black and white spiral on it! 😁
@@DarkAeroInc maybe mount a 20mm cannon through the centerline
Can't wait to see this up there
I like burring the round stalk in the spinner , good idea
Nice Job Guys.
Awesome Video!!!!!
That front module of spinning could also provide a great camera mount. Replace it with a transparent substitute and you'll have a great view out the front.
Great video! The washers look interesting. I recently faced a similar challenge with carbon fiber and countersunk screws.
"tinnerman washers" or "countersunk washers" in a google search will give you a lot of options
@@DarkAeroInc Thank you! :)
This whole channel is just too cool.
I'm curious how you balanced the entire unit, prop and spinner. What has been mad is very pretty!
You guys are outstanding. 100% cool imo
Outstanding layout! I love the feather mode!
I think it looks like a propeller on a mini turboprop when it’s in the feather position. 😎
@@DarkAeroInc True Story Time... Be careful when getting refueled by an FBO fuel attendant. You might end up with Jet-A instead of 100-LL. Happened in Tyler, Texas because the twin he was flying had featherable props on the ramp in feathered position. When the attendant filled the tanks mistakenly thinking he was filling a turboprop. The pilot lost power 5 minutes out and landed over a highline then under on a state highway and dead stick taxied into a bar parking lot!
@@willhibbardii2450 Yikes! Definitely will remember not to park with the prop in the feather position. The fuel cap holes on our wings are sized small enough so that it should prevent inserting a Jet-A fuel nozzle but still gotta watch out for fueling errors. Thank you for sharing the story! :)
@@DarkAeroInc , Glad you enjoyed it. Learning from the dumb stuff that has happened to pilots is a good thing. I know I don't want that happening to me. I've had other pilots laugh at me for doing complete ground checks after getting refueled sniffing it and checking the sumps. Good plan in having sized fuel holes!
@@willhibbardii2450 And amazingly, sometimes warning placards don't even help! Ya can't fix stupid!
I like your solution to eliminate overlaps in the CF. I have a suggest for cutting the openings for the prop. Use a hole saw to cut the radius portions and then follow-up with an oscillating saw to cut the straight slits. I would recommend using a backer to prevent damaging the inside surface. Something like a wood mandrel, but you might be able to get away with using tape.
Thank you for watching and for the suggestion! I'll give a little more info on why we selected the tools we did for cutting the blade holes. Since the DarkAero 1 will be a kit aircraft and cutting the propeller blade holes will be a builder task, we set up this step with the builder in mind. Using a large diameter hole saw to cut the arc portion of the blade hole would be difficult to control and less precise on the curved surface of the spinner. The moon shaped blade on the oscillating tool gives more freedom in your cut path which is necessary on the blade holes because they are not truly circular; the blade hole is a circle projected onto the angled face of the spinner. The blade we chose makes clean cuts with minimal disruption of the cut edge. The final shape of the cut can be cleaned up and corrected in small amounts with a sanding block. We like the hole saw technique best for cutouts on flat panels. A good example of this would be when builders use the hole saw method to produce circular hard point reinforcements for the engine firewall.
Amazing looking plane.
The body combined with the spinner looks very sleek!
Is it needed to cover the edges of a piece of carbon fiber to prevent water from getting into the material?
Looking forward to see the beast firing up.
Very interesting video. I just put a larger spinner on my Tailwind W8 and had to use the bulkhead in the nose area. Cools better in the summer but found out it cools a little too good in the winter here in Michigan lol. The spinner is off of the RV aircraft.
Not sure if it did anything as far as micro miles per hour so to speak but it does look better. Startled me a little bit at first and I thought about calling the airplane Pinocchio but decided against it. Anyway excellent video. First one I've seen. I hit the like and I will subscribe.
For the future, might have a look at the LiquidPiston engine that is being put into military drones. It has better efficiency, lower weight and would allow for a much narrower front. Also perhaps of interest, check the Smartcarbs made by Technology Elevated. These would increase range over injection, adjust to height and humidity. For slightly better mileage and cooler engine, check the Pulse Jet inserts by Steve Scriminger. Whats the glide ratio with feathered propellers? wont you get better range with longer, thinner wings with higher aspect ratio? on my old BMW boxer motorcycle I use RVS treatment, which extends engine life and cooler oil (plus a little bit of power improvement and mileage, but not much).
Nice!! I'm working on something very similar.
looking good
Love you guys...thanks for being part of the flying community!
Why not use a type of dampener? Yes, I know it adds a little weight but this would permanently fix any imbalance issues. You could fabricate them based on a similar designed used in car engines to balance the crank, which is basically what you're doing here.
Will there be any intelligence built in to prevent the prop from feathering while the engine is under power?
Thank you for watching and good questions! Final balance is achieved by adding weights onto the spinner backplate to offset any imbalance forces. There is logic in the prop controller to prevent feathering while the engine is running. There is an RPM sensor in the brush head assembly so the prop controller knows what the engine is doing.
Beautiful engineering. This aircraft looks like it would be a great platform for an EV version in the future.
Thank you for checking out the video and the kind words! We agree on the EV end. :)
Love your videos guys, very inspiring. Keep it up!
Amazing video !
Did you buy the seamless carbon fibre cloth as a COTS item? If so then from which vendor?
Absolutely love the way you share your knowledge, engineering concepts and experience in such a short video !
Thank you! We purchase the carbon sleeve in a long roll and then cut it to length. The specific type isn't public information but a google search of "carbon fiber sleeve" will yield many results that are similar to what we use.
Great stuff, as always, guys!
Question - are the spinner screws longer and safety wired on the inside of the spinner?
Do you worry about the screws "vibrating out" (much like the screw that was bouncing about in the "imbalance video clip" you had shown)?
Hi! Where did you learn how to design/size the carbon fibre parts? I'm talking from an engineering perspective, how do you size the components? Any good resources you recommend? Love your very inspiring work, thank you for posting all these videos!
Be careful about narrow prop extensions like this one, they work great when everything up front is balanced and acft isn’t in unusual attitude, but in high P factor during slow flight they can flex and cause the spinner to grind against the cowl. The P51 has this problem and can ruin the whole spinner flying nose high in slow flight. Also if you get a bird strike and the prop gets off balance, you want the extra margin of safety with a wider extension that can handle the vibration.
You guys are doing a wonderful job. Please tell me you have considered an augmentor tube exhaust system. It's the only thing in aviation that is free.
Great explanation! I also enjoy the two piece design with the nice stainless hardware, looks good. How many of these are you planning on selling and for how long before they're discontinued, ballpark?
Yaaaay finally
Amazing and Exciting ... this year I guess we will have THREE awesome aircraft in the air Scrappy, Raptor, Dark Arrow ... awesome names... awesome airplanes ... and of course few the other planes which I am sure are there abut am not aware of!!!
What a pleasure and treat it has been !
Meanwhile a small tiny request ...could you please link me to the information on the inner workings of the way the Pitch is actuated.
Thank you Neville! We discussed the pitch change mechanism is this video: ua-cam.com/video/riOTy9m0WTY/v-deo.html Cheers!
You guys are having the time of your lives. So jealous,
Like all the thought and ingenuity that goes into these products. Would you need to balance every spinner for the specific prop and have it paired with a blade for balancing? Or are the tolerances of the props and the spinner tight enough, that any imbalance is within spec of the chart and equation you mentioned?
The spinner and propeller get final balanced as an assembly so technically they are all paired.
You probably know that the long prop shaft extension creates a longer moment arm if any propeller imbalance exists. That translates to the root of the prop shaft and stresses bearings, seals, prop bulkhead bolts, engine shaft flange bolts. The vibration then works its way thru the engine mass to the airframe/engine mount and could create vibrational stresses. Just throwing that out there as a thought that might require contingencies later.
Lower weight can mitigate this.
Nice. I'm sure you guys have talked to your air racing buddies about the spinner to cowling gap and aero drag at that juncture.
Definitely a little bit of an aerodynamic "dirty" area at the junction of the spinner and cowling but no good way around that. We have to keep a little clearance there to allow for relative movement between the engine + prop + spinner assembly and the cowling. The holy grail would be a perfect transition there with no gap! 🤓
Looks fantastic. What state would the spinner come in with the kit? Are the holes for the propellor cut? Is the bolt pattern on the aft bulkhead already cut? Excited to see this plane fly!
Excellent question! The spinner in the kit would be made up of the forward and aft spinner segments plus the two internal bulkheads. Builders would bond the two segments together, cut the blade openings, and install the fasteners. We had to position the blade hole locations with templates but now that we have the hole size and position more firmly established, we may add some cut features into the mold to ensure builders locate the holes properly. We haven’t finalized a production method for the bolt circle pattern on the aft bulkhead. It needs to be accurately positioned which suggests CNC but I’m thinking there is probably a more efficient method using a drill template/jig. Thanks for watching!
Really cool! When is the next Q&A going to be?
It's coming up on the 4th @ 7:30 PM CST!
I clicked like 👍 before I even started watching
Curious if you crunched the numbers on making this a ground-up electric?
Joule for joule an electric motor mass is 25% that of a gas engine. That mass reduction can be allocated to energy storage.
Today's batteries are power dense enough and can be distributed around the air frame for optimal balance.
Also:
No aero fouling by combustion air intakes.
No necessity to compensate for altitude related air density.
Love weells aluminiun, i see the future 🤩
awesome
can you use a floid balaner like a blancer at the end of a Car Rank attach it to the end of the spinner and that should help
Glide ratio should be phenomenal. Great job guys!
Edit: Will there ever be a DarkAero 2 4 seater?
Can’t say we haven’t thought about a DarkAero 2. 😏 One airplane at a time though! 😁 Thanks for watching!
@@DarkAeroInc Well I only ask because by the time I get into my 50's in about 5yrs and buy my 1st plane, you guys will have that option. 😁. I have no problems with a 2 seater to start out though but when the family grows you know. 😉
@@DarkAeroInc A DarkAero 2 would be really interesting.
I'm curious to know what speeds you anticipate the DarkAero being used for cruise speed? I'm not seen any numbers - perhaps they have not been released yet. Thanks in advance. This is going to be a beautiful aircraft.
I DIG IT. Any possibility of popping it into beta with that prop to decrease landing rollout?
No prop beta with this guy unfortunately.
TLAR method is used all the time. That Looks About Right
Hey this is awesome work! I'm just wondering what kind of washers your are using for your countersunk screws, it all looks nice a flush with the conical shape? Did you counter drill into the carbon fiber?
besides having a better balanced design, do you plan on removing the rotating assembly to have it dynamically balanced? Like adding a sticky weight here or there to get the best possible balance?
We will dynamically balance the propeller and spinner together as an assembly with the engine running. Balance weights get bolted to the aft bulkhead to offset any imbalance forces.
By feathering the blades they generate maximum torque that needs to be offset with aileron. Does that relationship get optimized to get the most drag reduction by minimizing countertorque and its drag?
Could you thermoform glass or carbon panels? for production speed.
Your CAD work is awesome! What program are you using?
I just watched your vid where you explained your switched from Solid Works to Onshape. VERY impressive work, guys!
Can you tell us how the contacts are constructed on the brushes that send power to operate blade pitch? Specifically I'm curious if they roll on the rotary contact surface.
Unlimited funds..... I love it :)
I can't help but notice there are a lot of design similarities to the Nexus NXT. It's interesting how function (going effing fast) dictates similar form when the designers really know what they're doing.
Great content as always. What is the diameter of the spinner?
Thats a big spinner....... good
A turbulent boundary layer can delay the seperation point and reduce pressure drag. Is it worth inducing turbulence in the boundary layer at the spinner?
Those are nice engines from a company that made race engines. They now have an enhanced version with turbo and 220hp. Are you going to upgrade?
As a safety feature, would there be any failsafe mechanisms to prevent the props from feathering while the engine is running?
How are the Gyroscopic effects of the motor and Prop assemble considered, if at all?
Hey Ryley, as you know, I Love the spinner. When will you sell me one? ;)
What technique is used to rotate blades around its own axis?
Where do you get sleeve fabric that big in diameter? The largest one I can find online is 6"
What kind of mould sealer are you using to seal up the mdf and get the part off?
We seal the MDF with epoxy, sand it lightly, then coat it with mold release. We've also used wax successfully too.
Я очень впечятлен выполненной работай, в чем секрет такой акуратности?
Wonder where you can buy contra rotating propellers / systems
8:19 These are beautiful screws. I actually need to purchase something like those for aesthetics. Do you mind giving a link to what they are and where to buy them? I know you mentioned quick bond.
The screws we used are MS24694 stainless structural machine screws with 100 degree countersunk washers. www.aircraftspruce.com/catalog/hapages/ms24694.php
@@DarkAeroInc Thanks, DA. Actually it's the combination of the screw and the washer that gives it that aesthetically pleasing professional look. Do you mind giving a link to these washers too? :)
My apologies for bothering you...
@@danl.4743 No worries! Forgot about the washer link. Here is what we used: www.aircraftspruce.com/catalog/hapages/stainlesswashers.php?clickkey=3020239 Make sure you select the washer size to match your screw size. Good luck with your project!
@@DarkAeroInc Thanks!
Nice splaining! I was really gung-ho on bush planes, but now you got me thinking "fast is sexier!" Speaking of fast, will the DarkAero's prop have BETA? That'll keep the weight down on brakes.
Thank you Tony! Our prop does not have BETA mode, only feather function. Airmaster does make a prop controller with an option for BETA though. Typically this is selected as feature for seaplanes so they can taxi and maneuver on the water better.
@@DarkAeroInc Hmm, since it's a kit, it may be a good option to offer. I'm thinking about ways to preserve my brakes. What do you think?
do you apply CFD before making any of these?..and was there any engineering applied to look at the effect of the longer prop shaft?. the longer they are, the worse the longitudinal vibrations and where in the bearings. there are other issues also but generally the shorter the shaft, the better. im interested in the engineering you did before making these things.
Yes they did do CFD using Simscale. There's a video on it. They also verified their CFD results with wind tunnel tests.