Discussion in 'Workshop Tips and Secrets / Tools' started by Armilite, Sep 18, 2018.
Wing weight will depend on it's structural design. Not the aerofoil.
Sticking short wing blocks together is a lot of joints. They will be structurally annoying. Why not 3D 'extrude'. Just keep pulling the print away from thw printer and you can do the whole thing in one. Sliding spars in afterwards would need good accuracy.
At model airplane scale 3D printing an entire airplane is doable now. Here is my 75 in span Corsair that is 100% printed from common PLA filament. It's only a matter of time before large enough printers and strong enough materials are available to produce full scale planes.
Having done my share of 3D printing and routing and other processes, having had parts made on the cheapest of FDM to the most cutting edge professional equipment and seen how they work at every level along the way, my take-away for now is that the current level of consumer and prosumer FDM is not something I'm keen to bet my life on structurally in any way, shape, or form. I've printed a lot of parts and seen every way that they can fail, warp, tweak, etc. And I'm not super impressed so far, even with some of the nicer filaments.
The assumption has to be, at a minimum, "when these plastic layers delaminate, what will fail next?"
And that's when the layer bonding is pretty good! But you stack enough layers and eventually one is likely to be just a little sub-par. I've printed a lot of simple parts that just pull apart into sections immediately cuz a setting was off or a butterfly farted in the room next door and caused a draft, or who knows what; but some look good until weeks later some nominal use cracks it along a layer bond line that just happened to be first to go.
Because these airplanes are cycling a lot, and these little UL engines are not exactly free of vibration (e-motors notwithstanding), there's just bound to be failures over time with plastic FDM parts.
There is printing tech out there that makes parts I would be willing to hang on. But that tech is either on million dollar machines or on units with a tiny build volume (or both) so no 3D printed wing sections here. None of it seems to come close to eclipsing good 'ol cut profiles and a skin over top. I wish it were another way, and eventually we'll get there, and people experiementing with it is how it'll progress to be sure. But I'd start with fairings and other stuff, see how it holds up over time and take note of how it fails.
Yes, each Wing (Avg 16' to 18') will be a lot of joints depending on what Size Panels you use, 6", 12", 18", 24" Wide. The (2) Aluminium Spar Tubes act as Guide Rods, and those Small Holes in the Panels could also Act as Guide Pins Designed into the Panel to Help keep things Flush. Being Hollow, allows you to also Bolt/Rivet/Screw/Glue the Sections together. Most Tube & Fabric Ribs are just Thin Wall Aluminium Tubing with Plactic Ends just Riveted onto the Spars. You would be using the same Aluminium Spars and Aluminium Tension Tubes or use Carbon Fiber Tubes which Cost more, but Saves Weight. The 3D Printed Panel parts is just replacing the Wing Sail and Ribs. It would give you a better Smoother Airfoil. Being a One Pieice Solid Part would make them very Strong. Those Rib Plastic parts are made from ABS. Nylon or Carbon Fiber 3D Printer material would be best.
Show me a $500 Extruder Setup?
Just Curious, what is the Weight of the real Airplane vs your Scale Model?
What is the Hp of real Airplane vs your Scale Models HP?
What is the Speed of the real Airplane vs your Scale Models Speed?
Part 103's are Restricted to about 63mph.
While it's True you have to get the Setting Right to get Good 3D Printed Parts, you also have to Pick the Right Materials to use, not all will Work. Nylon or Carbon Fiber is probably the best choices and there both Exspensive. Maybe ABS even. If you was trying to do this for High Speed Aircraft I would maybe agree, but not for these low Speed Ultralights. Most of these 2 Strokes used on Part 103 Ultralights can be Balanced better as Props can also be Balanced.
When New Technolgy comes out, it's always Expensive. A CNC Mill/Lathe that cost half a Million years ago when they first came out, now cost $30,000-$60,000.
You do have different Types of 3D Printers all fighting for 1st place. For most Home Guys and Small Shops, a 3' x 6' or 4' x 6' CNC Table is sufficient.
Even if you just 3D Printed an Airfoil Rib Skelton that Slipped over the Spar Tubes and still used the Standard Covings.
looking at the thickness of the ribs of that model.....about the same thickness of a "full size" aircraft .025 aluminum on a full size. Will work fine on a model ....grossly too weak for a full size or when made thicker in soft plastic too heavy. We are not there yet. (Are we there yet?)
The CNC router is a better option, you can cut aircraft grade materials.
Strange question...but here goes.
Full size Corsair is over 10,000 lbs; model is 12 lbs. HP is 2380 vs 2. Speed is 440 mph vs 60.
Span 41' vs 75"...
I don't know Why you think it's a strange Question. Your RC Model is Built at a certain "Scale" of the Original Airframe which is 100%, only made from different materials than the Original Design, and with a different Weight/HP motor, and it still Fly's. As you say, it flies 60mph, similar to a Part 103's Max Speed of 63mph and the 3D printed Wings don't Break or Fall Off. For a Part 103 Ultralight were talking Max Weight of 254lbs, but it can be lighter.
Like a Phoenix 103 with a Hirth, F-23 50hp is 254lbs and has the Highest Useful Load of 396lbs. A Hirth F-23 Install weight is 78lbs with Electric Start. So 254lbs - 78lbs = 176lbs for Phoenix 103 Airframe!
The Aerolite 103 says Empty Weight 235lbs with a Useful Load of 365lbs vs 396lbs for the Phoenix 103. They don't state with what Engine, they just say Engine Power Requirements 28hp. - 50hp. I would assume that's with the 28hp Hirth F-33. Weight: 35lbs including exhaust sys. - 40lbs W/re-drive - 45lbs W/elec. start.
235lbs - 40lbs = 195lbs for Airframe.
235lbs - 45lbs = 190lbs for Airframe.
So even though they look the same, they're slightly different.
A Simonini 54hp Single is 70.5lbs ready to Fly. So about 8lbs lighter than the Hirth 50hp.
A Rotax 277UL. Dry Weight: 29.5kg (65lbs) (complete including Gear Reduction Drive and Exhaust system). A Belt Drive would save some Weight as a Tuned Pipe would be lighter also. A 277 can be Big Bored up to 82mm for more CC/HP.
So, Ball Park, most Tube & Fabric Part 103 Airframes will probably fall into that Airframe Weight Range of 176lbs to 190lbs.
Unlike Scale Models, for Part 103 Ultralights we can only use Lighter Stronger materials and lighter Engines that make same or more HP then Original Design used.
Well what really matters, and what a program like Solidworks or Fusion 360 is actually pretty good at, is modeling a shape and then determining what that resulting weight should be. It would be pretty trivial to model up an example rib in metal, plywood, foam/carbon, fiberglass composites, thermoformed plastic, coroplast plastic, and in 3D printed plastic, and then between these get a direct comparison. The main key is each example rib be designed such that it could carry the load for the entire service life of the vehicle.
We know Part 103 does not have any specifications however a prudent designer would design to a safe load and we have examples of those loads in the "certified world".
so lets look at the load.....254 + 200 pilot + 32 fuel + 35 parachute=521 # your numbers may vary. So lets say 4.4 Gs utility category.
521 x 4.4= 2292 lb approximately,your wing should support in a load test without going past yield ,...taking a different set, deforming etc. x 1.5 = 3343 lb it should not fail at ultimate.
I say approximate because you can deduct the weight of the wing in the original weight but in round numbers this is close enough for jazz.
Will that plastic wing support those weights and how much will it weigh.
If you want 6 g limit like the aerobatic it will have to weigh more, and what is the design limit of a fighter aircraft 12 G ????
We're not comparing a Certified Aluminium Airplane Wing here, we're comparing a 3D Printed Wing/Airfoil Shape to a Simple Tube & Fabric Part 103, Ultralight Wing. Could we 3D Print say 1ft, 2ft, Wide Airfoil Panels slid onto the Spar Tubes to makeup a Modular Wing using some of the best Airfoils. Your going to use the same 6061 Tube Spars and 6061 Cross Tubes or go with Carbon Fiber Tubes. Each Plane is going to face different hurdles.
I need to design to more than 4.4gx1.5 in the wings if I use coro as the stuff creeps. At a design loading of 10g, creep shouldn't be an issue. At 10g, nothing else happens to be an issue, either... Creep is another design consideration you may or may not need to factor in to your calculations. Fatigue is a factor for aluminium, but not Coro. You picks your material and then work out how, exactly, to stop it failing.
Your ribs and skin are going to be under load when in flight. If they weren't, you would have no lift.
Yes, that type of Testing can be done with many different Types of materials in CAD, but the whole concept is Based on, Can it be 3D Printed into a Complex Shape as a Solid Unit, so just the Materials that are available for that should suffice. Only Plastics with High Melting Temps and High Strenght would probably Work like Nylon and Carbon Fiber. Every Material Fails eventually from either Wind, Water, Rust, Corrosin, Fatique, Abuse, Poor Engineering, Type of Fastners used, etc. Your not going to 3D Print any Material as Thin and Strong as Aluminum used on Standard Airplane Wings.
You're probably talking at least 3/16" to 1/2" thick in certain Areas. Those Standard Ultralight Wing Ribs are Avg. 1/2" .058" Wall with ABS Plastic Connectors used on Both Ends, Riveted to the 6061 Aluminum Spar tubes. Some Manufactures have used Carbon Fiber Tubes Epoxy Glued. I have no doubt a Rib Airfoil Shape could be 3D Printed, or just CNC Routed/Laser/Water Jet/Milled out of the many other materials available and then just covered with Standard Wing Sails that have been used for 40+ years.
The whole concept is, use the (2) Standard Aluminum Spars and Cross Tubes, but Replace the Wing Sails & Ribs with just a Solid Airfoil Shape 3D Printed in 1ft and 2ft Wide Panels to make a Modual Wing.
How many Pounds of Pressure will Standard Wing Sail Material take vs these different Plastics?
How many Pounds of Pressure will Standard Ultralight Aluminium Ribs & their ABS Plastic Ends and Rivet Connections take?
The nice thing about 3D CAD and 3D Printing, you can make a Complex part. Is you can also Test it in some of these 3D CAD programs using many different Materials to see their Strenght and Weight and Cost.
For USA Part 103 Ultralights you want #1 a High Lift Airfoil with a #2 Low Stall Speed, and I would make it compared to the Phonix 103 for a 396lb Useful Load. Tall, Wide, Big and just Chubby people like to Fly also. You can Design it for that 35% of the Population that weighs 200lbs or less, or 99% of the Population for Sales. I was 6ft 197lbs, 196lbs, 197lbs in 10th, 11th, 12th grades for Football. Got Married at age 19 to a Good Cook, weighed 245lbs at age 25 when I started building our House, a year later when finished I was 205bs. My two brothers are 6ft 5in and 6ft 6in and both 230+. Most Americans, Men and Women are over weight today. So for Sales do you Design for that 35% 200lb or less Catagory, or for that 99% Catagory? The Majority of People in the World fall into the 6ft - 6in Height and 140 to 350lbs. So Design it for the Max Sales potentical.
True, but we're talking Standard Wing Sail Material with Aluminium Tube Ribs with ABS Plastic Connectors on both ends just Riveted to the Tube Spars, vs a One Piece Airfoil with Bulk Heads and maybe Ribs/Honey Comb Designed inside for great Strenght. You're still using the Standard 6061 Aluminium Spars and Cross Tubes or go with Carbon Fiber Tubes to Save Weight, but Cost more.
You might be able to go with a Thinner Hollow 3D Printed part and fill the Cavities with that Spray Foam that expands.
"Will that plastic wing supports those weights and how much will it weigh. " That is the Million Dollar Question!
Let's not Stray from the path, this concept is only for a Standard USA Part 103 Tube & Fabric Ultralight for now! Most Part 103's ever made are not built for Aerobatics. The Phoniex 103 sets the World Bar at 396lbs Useful Load and makes Part 103 254lbs with a Hirth F-23 50hp Engine. Most Standard USA Part 103's fall into the Design Load Limits @ Gross Weight of +4 / -2. With Floats or a BRS added you are allowed more Weight than the Standard 254lbs.
For Sales purposes, I would follow the Phoenix 103 Useful Load Specs. We know the Max Empty Weight is 254lbs, and we know the Max Fuel is 5 Gallons(30lbs) So 396lbs - 30lbs = 366lbs for Pilot & Bags! Or we can just say 254lbs + 396lbs = 650lbs would be the Target.
Specifications (Phoenix 103)
Data from Kitplanes
Length: 17 ft (5.2 m)
Wingspan: 26.8 ft (8.2 m)
Wing area: 124 sq ft (11.5 m2)
Empty weight: 254 lb (115 kg)
Gross weight: 650 lb (295 kg)
Fuel capacity: 5 U.S. gallons (19 L; 4.2 imp gal)
Powerplant: 1 × Hirth F-23 twin two-strokehorizontally-opposed, two stroke aircraft engine, 50 hp (37 kW)
Propellers: 3-bladed composite
Cruise speed: 63 mph (101 km/h; 55 kn)
Stall speed: 28 mph (45 km/h; 24 kn)
Range: 100 mi (87 nmi; 161 km)
Rate of climb: 1,100 ft/min (5.6 m/s)
Wing loading: 5.2 lb/sq ft (25 kg/m2)
Hirth F-23 521cc, 50hp Weight:
78lbs, including Belt Reduction Unit, full exhaust, and Electric Start, or 71lbs with Recoil Start, Belt Reduction Unit and full exhaust.
Hirth F-33 313cc, 28hp Weight:
35lbs including Exhaust sys. - 40lbs W/Belt Re-Drive - 45lbs W/Elec. Start.
Simonini 400cc 54hp Single 32kg/70.5lbs.
Rotax 277UL 268.8cc, 26hp Weight:
Dry weight: 29.5 kg (65lb) (complete including Gear Reduction Drive and Exhaust System)
Kawasaki 440 Twin 436cc, 40hp with a Muffler.
Engine Dry weight: 49lb (22kg)
It should be easy to calculate the answer or derive it with test panels.
The numbers that need to be researched and posted are......for the strength, stiffness, and density of the various 3D print materials.
Scott has also mentioned that these materials also have a tendency to De-laminate in use, so even then our strength and weight calculations would need to be tested or very "over-designed"
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