What could be done to reinvent the Affordaplane to a more homogeneous project?

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erkki67

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I'd be cautious about any heat formed plastics myself...

HIPS - 3d printed version of polystyrene - has a glass transition temp of around 88c - meaning that's when it becomes malleable and permanently can be deformed.... at lower temps with pressure applied - it'll still deform.

I know of one thing I printed in hips that permanently deformed inside a car on a mild-er arizona day...
Mild Arizona Day, this is what we call a heated up Sauna!
 

SpaceRat

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I was intrigued by the use of "thermoformed polystyrene" used for wing ribs on the production models. I can see certain advantages in the forming of flanges for stiffness and simplified attachment to tube spars. The sheet material could possibly be used for a formed leading edge and bonded to the ribs with adhesive. Hard to beat a light gauge aluminum formed rib for strength to weight but it appears polystyrene is viable in a light aircraft construction. Once you have the form you could knock out dozens of ribs is a short time inexpencively with thermoforming.

Anyone have any experience thermoforming aircraft parts?
Back in the 80's I built a vacuum form machine and made ribs for an experimental aircraft from 1/16" Lexan (polycarbonate).
These ribs were virtually indestructible. However, I opted for built-up wood ribs instead, as I had fuel tanks in the wings, and polycarbonate can become "crazed" and develop micro-cracks from gasoline fumes. I don't need a rib failure in mid-flight! Polystyrene is also sensitive to gasoline fumes, but may work well in an enclosed environment with no fuel tanks.
I am currently building a RagWing Rag-A-Bond RW11 , and since the fuel tank is not in the wings, I may drag out the old vacuum-form machine and make some Lexan ribs.
 

Aerowerx

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Somehow this doesn't seem right.

Plastic as a structural component?

In my experience as an engineer and maintenance tech, that is a failure waiting for the worse possible time to happen.
 

addicted2climbing

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I'd be cautious about any heat formed plastics myself...

HIPS - 3d printed version of polystyrene - has a glass transition temp of around 88c - meaning that's when it becomes malleable and permanently can be deformed.... at lower temps with pressure applied - it'll still deform.

I know of one thing I printed in hips that permanently deformed inside a car on a mild-er arizona day...
Why did you choose HIPS as a material? Its hard to print and definitely not the best choice for AZ. Did you try any other high temp materials? I am currently converting one of my Ender 5 machines to print Glass Reinforced Nylon and will try some other high performance plastics. Printing full ribs that resist heat would be tough in any material and luckily I am just printing some rib attach clips. Currently I have printed these in PLA and PETG and both printed well. PLA is not that UV stable but it was surprisingly tough. Took me a good long time to break it. In PETG it broke easily, but that was a printhead temp issue and once I got that sorted out it was as tough as PLA but in one place the layer adhesion was less than optimal. Nylon has amazing layer adhesion and I am hoping this is the ticket. There are other newer materials now even better and I plan to try them as well.

On a another note, I did print an iPhone yoke mount for a C182p that is awesome and I have an integrated charge battery on it. Its in PETG to help with a hot cockpit on a CA day. Its in black which is not best choice of colors to avoid heat, but its what I had on hand. I may print it in silver instead. So far its good but I have not been able to test on the ramp while having lunch and its in full sun. Pics shown are first print so its a bit ratty. Will clean it up when I make a new one in lighter color for the sun. I plan to modify the design for other aircraft and maybe sell printed parts. This one is for an Ipad Mini but I could modify it for a full size by just changing the clip.

Marc

Yoke Mount 1.jpegYoke Mount 2.jpegYoke Mount 3.jpeg
 

ElectricFlyer

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Glass fibre ribs have been used in many designs, but I think 3d printed ribs would be unsuitable.
What about 3D print using Nylon w/CF. "some blends at 25% carbon fill are literally comparable to aluminum -- they’re calling it black aluminum".
I think the real downside will be the printer size needed.
Cheers
 

Hephaestus

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Why did you choose HIPS as a material? Its hard to print and definitely not the best choice for AZ. Did you try any other high temp materials?
4+ years ago, needed a car part, someone spied it on another forum... HIPS was chosen because it was better than abs/pla and not flexy like nylon/petg. Sent it to Maine - ending up in az to melt in a car, desert climates wasn't a factor I considered at the time 😂

Mines still going strong all these years later, but we don't get the heat of the desert.
 

addicted2climbing

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What about 3D print using Nylon w/CF. "some blends at 25% carbon fill are literally comparable to aluminum -- they’re calling it black aluminum".
I think the real downside will be the printer size needed.
Cheers
My only concern with CF/Nylon is that CF and Aluminum dont do well together and tend to pass electrons and cause corrosion. Unsure if it woudl happen in a matrix of nylon, but figured I would take the safe route and choose the Glass reinforced Nylon instead. Plus it does a bit better in vibration not being so rigid as CF/Nylon.

Can anyone shed light on if I would need to worry about the CF to Aluminum issue if the CF is in a nylon matrix?
 

Aerowerx

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CF or glass reinforced polymers?

IMHO...
The reason CF or glass is so strong is that it is in long continuous strands. By reinforcing a polymer with short cut-up strands you are still relying on the polymer. Yes, it may be tougher but not as strong as doing a conventional layup with woven fabric.
 

Hephaestus

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I'm still stuck in the you're probably using your printer to make jigs, tools, molds. Not so much finished structural parts.

I mean I know they print boat hulls these days but...

Maybe for a marginal - very short service life technology demonstrator... But not something that'll last years or longer.

Even the larger printed RCs I do have a relatively short life (about equivalent to my dumb thumbs intervals). My oldest RC printed model got retired because the PLA+ seems to have degraded to where the flex was an issue (and it has carbon tube spars).
 

Mohawk750

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The Butterfly was built of 2024T3
In the article that was quoted stated that the prototype butterfly was made from aluminum but production kits used thermo formed polystyrene ribs.

Certainly temperature range and uv resistance need to be considered. I tried to look up the specs on some of the plastics but didn't get very far. Most things have been tried in the past but we may have better materials now that would support some out of the box thinking and adopting of non traditional materials, subject to appropriate testing.

Some fellas will be happy to whittle a Pietenpole out of a fence post and the next guy will want every part wrapped in carbon fiber! Neither of these options meet the needs of today's home builder. We should be looking for ways to keep cost and build times low while taking advantage of some more modern non traditional materials where appropriate. At least for relatively low performance lightly loaded fun flyers.
 
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Hephaestus

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They print Mountainbike frames, and those you don’t want to brake in the worst possible moments as well.
Ok let's be clear - there is one single manufacturer, selling a "3d printed" frame.

It's titanium laser sintered - not exactly something you'd have in your garage.

You can probably find some one offs - I'm sure there are some kicking around - that paola scooter was the rage in '15 - still required aluminum cnc frame members. But the strength isn't there in the typical plastics (reinforced or not), for structural use especially for aviation.
 

SpaceRat

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Somehow this doesn't seem right.

Plastic as a structural component?

In my experience as an engineer and maintenance tech, that is a failure waiting for the worse possible time to happen.
-------
Are you not familiar with the strength properties of polycarbonate compared to wood ribs or aluminum?

To group all polymers as "plastic" in your rhetorical question, "Plastic as a structural component?" appears to belie the possibility that you don't know much about "plastics".

There are literally THOUSANDS of aircraft flying today with "plastic" structural components - some with a majority of the structure of the aircraft being "plastic". In addition, there are thousands of different polymers, some stronger than steel by weight.

In closing, I would like to state that the "plastic" (polycarbonate) ribs we made by vacuum forming were so strong, that these retained strength and shape even after being driven over with a Chevy pickup truck - on asphalt.

I would like to see the state of aluminum or wooden built-up ribs after receiving the same treatment.

I am extremely surprised that as an engineer, you would be bereft of knowledge when it comes to "plastics" and the strength of these materials.
 

Victor Bravo

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The old engine mounts for most of my old R/C airplanes were "glass filled nylon" and they did not contain long continuous fibers. They were short "milled fiber" I believe. This seems like something that could be printed with a machine? Those engine mounts were pretty tough.
 

TFF

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All parts are measured in strength per weight, number of cycles it can be used, and can it be bought. If you can drive a car over a plastic rib, it’s probably too strong and can be lighter. Cycles are an unknown unless someone sticks their neck out and flies with them. Cost is always cost. If making a plastic rib and saying it’s great but using more standard means more standard is better. We always use better? The answer is no one knows until someone sticks their neck out. No Rutans in the audience?
 

Aerowerx

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-------
I am extremely surprised that as an engineer, you would be bereft of knowledge when it comes to "plastics" and the strength of these materials.
Electrical Engineer. Never designed with "plastic".

But when working on equipment, what sticks in my mind is that it is the small "plastic" parts that fail. Long before the metallic parts. And these "plastic"parts that fail are in high-stress locations---like a "plastic" door latch as an example.
 

nestofdragons

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Ok, let me tell what i know about these thermoformed ribs of the Butterfly. I thought to recall they were lighter than alu. Had one in the hand and i was really impressed. The wing of the Butterfly had a few ribbons internal to prevent them twisting inside the wing. Very light and very effective system to prevent deformation.
Alain Blondiau, who wrote a book about the many Belgian Flying Flea project through history, has a Romibutter. It has the wings of the Butterfly, but with a new fuselage. Looks more than a classic airplane. Those wings are a few decades old. Only deformation is that that some ribs trailing edge moved sideways. Just a bit. But the wing was still flyable.
So ... i would not underestimate the quality of the thermoformed ribs of the Butterfly.
2021-02-16 butterfly.jpg
 
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