Front Wing Cores

[polarboy]

What are you making wings for at the moment steve ? have you got a vac pump ? or the options to use prepregs ? If your using foam cores are you hot wire cutting them ? If your cutting them yourself you know you can use the outer foam thats cut from your core as a 1 off mould to give you a moulded finnish on your core ???
If your looking to do things "old school" both of kieths noakes books would be very good for you,If your looking towards more modern process,s i have just read a new book that covers modern era at williams about 3/4 years ago but I cant remember the title till i get home next week.
Lots of books about that are written by people that know a lot but havent actually done a lot themselves

[Mystery Steve]

I'm in the process of designing a single-seater track car, modeled in the spirit of LMPs. I just finished school, and I am looking for a job at the moment, so I'll have to procure the necessary equipment when the funds become available. In the meantime, I am in the beginning phases of the parametric design. Most of the bodywork will likely be made from fiberglass just for cost reasons. I'll make that decision after I cost everything out. The smaller components such as the seat/cockpit and the rear wing I'll probably make from carbon to save a few pounds.

I do have some experience with forming foam molds (link to pictures). These particular pieces were done using the moldless technique due to time constraints, but I've seen some methods for producing part lines on molds that seem simple enough. However, there is always more than one way to do something and it never hurts to hear other opinions. The large items, like say a big piece of bodywork seem easy enough. I'm more curious about ways to not only build tightly wrapped components such as wings, but also methods for mounting them to the car, whether it be by riveting a strut to the wing, bonding an aluminum mount to the wing structure, etc.

I've found this video dealing with construction of a wing for an RC airplane. I'd imagine that the techniques are similar for a car wing, I'm just not sure about the method they've used to bond the two halves. I've also found this tutorial that shows a method for attaching the endplates. I was curious to see if anyone had an opinion on these methods or possibly better ways of going about it. I'm also a visual person, so pictures are definitely appreciated, if you have some available that is.

[polarboy]

The last vid was good,thats the process i mentioned in my last post but the guy in the vid made life hard for himself.When you start an cut your foam core out mark out your wing profile on each end of the foam and mark datums every 20mm or so.Number the datum points starting at the trailing edge no1 to....whatever get a friend to help you cut the foam but do it in one go,cutting from no1.As you go along one person calls out the numbers so so the wing is cut evenly,when you get all the way back to no1 you will have your foam core but also your outer foam that you can use as a mould
Lay your carbon onto no hole release film an wetted out an then wrapped round the foam core an then placed back in the foam block it was cut from an the block an the block taped shut,after its cured strip the outer foam off an you have a finnished item,no need to fill or rub down,
Remove foam from the ends an glue in fittings for the endplates,solid ali tapped an helicoiled or kesert fitted or carbon/honeycomb/carbon sandwich with soild insert or 2 part bobbin
This is F1 circa 82/3

[Mystery Steve]

Yeah, I think I'm starting to grasp the concept of how to layup the molds. The last question I have is about the mounting of the wing support brackets in the middle of underside of the wing (labeled Upper Pedestal in the picture below). Is that bonded in as part of the layup process or is it bonded afterward? If it's bonded is there specific type of adhesive or surface preparation involved? Thanks for all your help so far. I guess I could use the riveting method used on that Bimmer forum thread, but it just seems like there would be a stronger way to do it.

[marcush.]

you would avoid mounting anything to the lower surface of the wing as here you want flow.
As for the mounting points-near the centre of the wing -you have to consider these are transmitting all the forces produced or received by the wing,be it downforce,drag and vibration.for that matter I would always produce a INTEGRATED
Wingmount solution ,possibly the best solution would be a box section consisting of two spars in the wing mount area where all the loads find a clear path into the wingstays.A purely surface mount wingstay is looking for desaster...but of course you could build a big shell type mount for the stay to bond to the surface..but ruining the flow and the downforce adding drag ...no good idea.
the spars could be buildup by carving channels into the foamcore filling them with cfrovings and embedding cf tubes containing threaded inserts for example..
of course adhesion is key there ..and best adhesion is achieved by having ripoff(peeloff) cloth placed on all bonding area .

[Mystery Steve]

Obviously, in an ideal world you would want all of your mounts to be on the high pressure side of the wing. On the other hand, since I'm just trying to figure out the best way to mount it period, that doesn't seem like the best idea structurally. Making mounts on the high pressure side isn't trivial structurally, considering both gravity and the force of the wing are working against you.

Also, from my perspective at least, this is only going to be a weekend track car and maybe a drive around on Sunday afternoon car, so absolute performance won't be critical for my case. If just using a foam wrap layup adds a couple pounds, but reduces manufacturing complexity, then it will be worth it in my case. I'm more concerned with making something that is structurally sound, has a reasonable range of adjustment, is simple enough to do in my garage over a couple weekends, and doesn't look like some piece of crap a high school student slapped it together in a day for his Honda Civic. I'll have to think about how I might do a combined rib/foam layup with the mounts integrated into the rib. I'll post a picture of what I'm thinking in the next couple days to see if anyone has an opinion.

[marcush.]

the weight of the wing should not have any major influence ..considering the wing will weigh a few kilos only even if you use a very unsophisticated method of production. and the forces it should generate to justify its presence should be a LOT more than that...so staic considerations are not what should hinder you doing it right.
If you shy away from even that ,then do mount it by using the endplates for example.this way around you avoid putting the loads into the skin only ...
in terms of tensile strength ..just look up the tensile strength of a simple m6 screw