Rapid Prototype of Fairing for End Use Product 1

[Chris843]

I'm basically in the process of designing a junction style fairing that will wrap around some butted tubular sanctions on a modified aircraft. They are somewhat complex fairings and they need to be manufactured in a timely manner. I do not have a lot of experience with composite materials nor rapid prototyping. So anybody have any recommendations on a process/material to make these one-off fairings that will be strong enough to fly on an experimental aircraft as an end product? Fiberglass, Kydex (or some other rapid forming thermoplastic) I'm even open to 3D printing options if there's a industry standard out there for doing it.

 

[dgapilot]

The rapid prototype method may work given the comments above, sectioning it for the size constraints of the 3D printer. Al in all, I still think the quickest way to make 4 fairings would be to bang them out of sheet metal. Section the model and band cut plywood to match the section lines. Build a buck from the plywood sections. Form aluminum sections to meet the buck and weld them together. You can pound out 4 scrap pieces and one good one in less time than it takes to do one FRP lay up. No worry about P-static with the sheet metal fairing. All the fairings will be to print since they are built on a buck that represents the 3D model. All you need is some good hammers and a leather shot bag. So much the better if you have a power hammer or Yoder Hammer and english wheel. Gas weld it as it is much easier to planish out the gas weld beads than tig weld beads. See this site for really good sheet metal forming info and materails

https://www.tinmantech.com/

David

 

[drawoh]

Chris843,

I have just been through installing stuff into a Dash-8. Getting everything approved can be very exciting. Make sure you know how you will accomplish this.

I am not aware of a rapid prototyping material that will not give off nasty gases when it burns. Do not rely on direct rapid prototyping. If you go to glass or carbon fibre reinforced plastic, be careful what grade of plastic you select.

Rapid prototypers can produce wax patterns, suitable for investment casting.

--
JHG

 

[rb1957]

i'd use the 3D printer to create a temporary mould (from the CAD definition), or maybe a temporary fairing (with speed tape) for flight test purposes to be glassed over for the final fairing.

Quando Omni Flunkus Moritati

 

[Chris843]

Thanks for the comments,

I'm in contact with a guy from Stratus to see if they have any case studies using FPM parts on this type application. Either way I do it there has to be documentation on it. Even if this is a one off deal, the customer requires documentation to reproduce these if they get damaged during mission. Unfortunately it's QRC and a program of record wrapped into one.

Any good reading material out there on exactly what a fairing drawing entails?

 

[berkshire]

Any good reading material out there on exactly what a fairing drawing entails?

I looked through my stack of drafting books and could find nothing specific to Fairing drawings.
It would come down to basic drafting skills.
In the past for a fairing Drawing, when I have had to do them, enough information has to be given to the mechanic to allow him to manufacture the component.
the process has been to set up stations at regular intervals across the part
Then waterlines or section views.
Each of these has been dimensioned to allow the mechanic to make an eggcrate model of the part.
He can then use this information to make a mold, pattern, or directly hammer the part out of sheet metal using the eggcrate model as a guide / gage.
You already have a solid model of the part. Make a drawing from the model then give enough section views with dimensions as supplimental views to allow the part to be made either with or without a 3D printer. This way a shop can Beat them out of sheetmetal, Thermoform Kydex, cast them, Machine them out on a CNC mill, or print them out on a 3D printer, either way you would have given enough information to get the job done.
B.E.

 

[berkshire]

Chris,
I got off on a bit of a tangent here and started thinking 2D, you want to keep this 3D, you need to look up ASME Y14.41-2003 for what you are trying to do.

 

[49again]

Chris -

During the flight test program to get the wing stores certified for our GV, we had to prove to the FAA that those stores would not adversely affect flight when they were covered with ice, so we created some "ice" from parts printed in our old Dimension (ABS FDM) printer. Worked really well for that application, but the parts were hardened somewhat with a coating of epoxy and floor-dry (like kitty litter) that was simulating a "rime ice" texture. These shapes survived just fine at GV speeds all the way to 51,000 feet....

Steve R.

 

[rb1957]

we too have used foam shapes to simulate ice.

my idea was only to use the 3D printed bulk fairing was for flight test ... print your CAD file (including holes for the staunctions), stick it on the plane, speed (or duct) tape it to keep it from getting blown off, modify it as necessary. then use the final shape as a mounld for a glass fiber fairing.

if "Either way I do it there has to be documentation on it." then i guess you're slightly screwed. As a flight test installation, the pilots flying and the engineer organising the show need to be satisfied. i'd've thought the use of speed tape was pretty universal. i'd've thought adding a fairing like this was pretty innocuous, there might be more of a question if this is on the fuselage roof (ie things flying off impacting the H. Stab).

Quando Omni Flunkus Moritati

 

[KENAT]

berkshire, Y14.41 is of pretty limited use to people actually documenting parts - it's of more use to the CAD companies in saying what the CAD system needs to be able to do. However, it's pretty much all there is for MBD at the moment. We reference it on the partial drawings we do for MBD parts.

Drawoh, I believe there are at least some flame rated plastics used with rapid prototyping, Ultem for instance.

Chris843 we've used these guys for some parts and they do have some Aero industry involvement by the looks of it.

https://www.solidconcepts.com/

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