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BioBa

Original Poster:

295 posts

38 months

[news] 
Monday 3rd September 2012 quote quote all
I am in the process of building a carbon fiber rear wing. I have access to a CNC cutter to make the foam core and a friend of mine has extensive CF manufacturing experience. I have no access to the Radical CF wing. Mine is the older style aluminium wing. Could someone please post a picture of how the wing bracket looks which attaches the wing to the rear wing mounting frame. I am in particular interested how the bracket is embedded/attached to the wing. Any additional photos of the wing would also be appreciated. Does it have the same profile as the aluminium wing?

splitpin

2,549 posts

83 months

[news] 
Monday 3rd September 2012 quote quote all
Here's one of the PR6's CF Main Plane; it's (both parts) 'embedded' i.e. no visible fixings on the outside/underside.

BioBa

Original Poster:

295 posts

38 months

[news] 
Monday 3rd September 2012 quote quote all
Thank you splitpin. So the bracket is attached internally with the CF laid around it? Looks clean but I wonder how the bracket is anchored internally.

I was thinking about making a bracket which is riveted to an internal aluminium base plate more like this:


dunc_sx

595 posts

82 months

[news] 
Monday 3rd September 2012 quote quote all
BioBa, my CF wing's mounted the same way as shown in your photo. Thought it was std Rad so either they've done it both ways or my wing isn't a radical one.

Rgds,

Dunc.

andylaurence

324 posts

96 months

[news] 
Monday 3rd September 2012 quote quote all
Mine's rivetted too, just like the photo. It's not a Radical, though.
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Coldaswell

61 posts

34 months

[news] 
Monday 3rd September 2012 quote quote all
Hi BioBa

The old tin wing is a different profile to the shiny but bloomin' expensive carbon one.

Myd

147 posts

108 months

[news] 
Monday 3rd September 2012 quote quote all
Have a look here, does this help? http://www.flickr.com/photos/16604067@N06/sets/721...

If you need any specific pics let me know as i have both the original alloy type and the Carbon version currently off the car, I could also stretch to providing some dimensions if it helps.

Myd

BioBa

Original Poster:

295 posts

38 months

[news] 
Monday 3rd September 2012 quote quote all
Coldaswell said:
Hi BioBa

The old tin wing is a different profile to the shiny but bloomin' expensive carbon one.
When looking at Myd's picture the profile looks virtually the same except that i have a small upwards facing 90 degre e lip at the trailing edge.
Thanks for the pictures!
In terms of dimensions (not profile) I was using the same as in the aluminium wing.
Do you know anybody in the UK who makes Radical cf wings at a reasonable price?

BioBa

Original Poster:

295 posts

38 months

[news] 
Monday 3rd September 2012 quote quote all
Coldaswell said:
Hi BioBa

The old tin wing is a different profile to the shiny but bloomin' expensive carbon one.
When looking at Myd's picture the profile looks virtually the same except that i have a small upwards facing 90 degre e lip at the trailing edge.
Thanks for the pictures!
In terms of dimensions (not profile) I was using the same as in the aluminium wing.
Do you know anybody in the UK who makes Radical cf wings at a reasonable price?

Myd

147 posts

108 months

[news] 
Tuesday 4th September 2012 quote quote all
There are a handful of companies that make cf wings that I know fit a Radical, try MVS Racing - www.mvsracing.co.uk

I am sure other names will be posted but I am only familiar with their work which some feel has been money well spent.

LCM

436 posts

82 months

[news] 
Wednesday 5th September 2012 quote quote all
BioBa said:
I am in the process of building a carbon fiber rear wing. I have access to a CNC cutter to make the foam core and a friend of mine has extensive CF manufacturing experience. I have no access to the Radical CF wing. Mine is the older style aluminium wing. Could someone please post a picture of how the wing bracket looks which attaches the wing to the rear wing mounting frame. I am in particular interested how the bracket is embedded/attached to the wing. Any additional photos of the wing would also be appreciated. Does it have the same profile as the aluminium wing?

This raises a number of questions.

Firstly you don't tell us whether you are going to use pre-preg, vaccing, autoclaving; resin infusion or wet hand lay-up. The choice of method will make a big difference to the weight, strength and cost of your wing.

You mention that you are going to cut a foam core. Are you planning to use this to make a buck or as the core of the final wing, wrapped in C/F cloth with a join at the TE? If the latter then are you sure that you can achieve a good and consistent bond between the core and the wrap? I ask because with my laminator we have been experimenting with this methodology and have been unable to achieve a consistent bond. Without this bond the normal cube rule doesn't hold and the wing is insufficiently stiff to take the aero loads and collapses prematurely (which can be, at least, unpleasant).

Remember that a decent sized wing with a decent section running at decent speeds will generate decently high loads (think a couple of hundred kg). So, both your construction and mounting methods need to be up to the job. Most professional wing makers use spar, spar and rib (sometimes with foam core infill) or (cheapest and easiest) a spanwise tube connecting upper and lower surfaces, normally at t-max; formed internal aluminium plate to give the pick up point and serious Aramid reinforcing around it to spread the loads. My personal preference is to also use a fabricted external aliminium saddle to connect the wing to the wing tower although you have to accept that this will disrupt the airflow more on the underside that the purely internal mount shown on Trev's pretty PR6 picture.

To be clear, the only place you can get a Radical wing is from Radical. However there are a number of other manufactureres who can supply wings of different profiles that will fit a Radical (amongst whom are, as Myd says, MVS)

Happy laminating!

Edited by LCM on Wednesday 5th September 13:45

splitpin

2,549 posts

83 months

[news] 
Wednesday 5th September 2012 quote quote all
LCM said:
........and the wing is insufficiently stiff to take the aero loads and collapses prematurely (which can be, at least, unpleasant).

Remember that a decent sized wing with a decent section running at decent speeds will generate decently high loads (think a couple of hundred kg). So, both your construction and mounting methods need to be up to the job.
Well said.

Unpleasant and probably much more for the driver and potentially likewise for the ones behind especially if he/she is in much the same 'open to air' (and debris) type of car.

LCM

436 posts

82 months

[news] 
Wednesday 5th September 2012 quote quote all
BioBa said:
i have a small upwards facing 90 degre e lip at the trailing edge.
That's a Gurney flap - an efficient little device with a L/D ratio c 3:1 used to either maximise -lift from a wing (where you are limited by dimensions or funds) or to fine tune aero balance.

I sell them in a range of sizes to bolt on or stick on but for collection only as they are not economic to ship (especially not to Oz).

Sorry!

Edited by LCM on Wednesday 5th September 17:25


Edited by LCM on Wednesday 5th September 17:27

BioBa

Original Poster:

295 posts

38 months

[news] 
Thursday 6th September 2012 quote quote all
LCM said:

This raises a number of questions.

Firstly you don't tell us whether you are going to use pre-preg, vaccing, autoclaving; resin infusion or wet hand lay-up. The choice of method will make a big difference to the weight, strength and cost of your wing.

You mention that you are going to cut a foam core. Are you planning to use this to make a buck or as the core of the final wing, wrapped in C/F cloth with a join at the TE? If the latter then are you sure that you can achieve a good and consistent bond between the core and the wrap? I ask because with my laminator we have been experimenting with this methodology and have been unable to achieve a consistent bond. Without this bond the normal cube rule doesn't hold and the wing is insufficiently stiff to take the aero loads and collapses prematurely (which can be, at least, unpleasant).

Remember that a decent sized wing with a decent section running at decent speeds will generate decently high loads (think a couple of hundred kg). So, both your construction and mounting methods need to be up to the job. Most professional wing makers use spar, spar and rib (sometimes with foam core infill) or (cheapest and easiest) a spanwise tube connecting upper and lower surfaces, normally at t-max; formed internal aluminium plate to give the pick up point and serious Aramid reinforcing around it to spread the loads. My personal preference is to also use a fabricted external aliminium saddle to connect the wing to the wing tower although you have to accept that this will disrupt the airflow more on the underside that the purely internal mount shown on Trev's pretty PR6 picture.

To be clear, the only place you can get a Radical wing is from Radical. However there are a number of other manufactureres who can supply wings of different profiles that will fit a Radical (amongst whom are, as Myd says, MVS)

Happy laminating!

Edited by LCM on Wednesday 5th September 13:45
Good points you have made and I have been spending a lot of time thinking about the issues you have raised. First I had planned to simply follow this thread http://forums.bimmerforums.com/forum/showthread.ph...
super fill the foam, use it as a core and wet hand lay the carbon fiber. Considering that the wing is 1700 mm long I was very concerned that having only a plain foam core would not be strong enough to withstand the load. Your comments that you have problems achieving a good bond between the foam and CF is an additional problem I have not considered. Are your bonding problems maybe related to the fact that you have not super filled the foam?
I have been building RC pylon racers in the past. The wings of these race planes take tremendous loads and I was trying to adapt some of the RC building principles on the car wing.
Building 4-5 ribs with a CF wing spar seemed the best solution to the problem but your idea of using a large diameter spanwise tube (what material are you using? CF?) seems even easier.
I still have not come up with a good solution to connecting the wing to the wing tower. I prefer not to use an external aluminium saddle but have not quite figured out how to do it.
I also do not have the right equipment to fabricate an aluminium end rib (it might have to be timber) to attach the wing end plates.
In the meantime MVS has provided me a quote for a 1700mm CF wing and I must say adding up all materials and hours required to build my own their offer is almost too good to refuse. Let's see what happens. By the way what else do you sell besides the gurney flap?

Count Johnny

715 posts

82 months

[news] 
Friday 7th September 2012 quote quote all
Not a Radical wing (although it is a radical wing) but you get a fairly clear view of what's going on.



Probably worth pointing out that it is bonded on with proper structural adhesive and the rivets are not your common and garden pop rivets.


BioBa

Original Poster:

295 posts

38 months

[news] 
Friday 7th September 2012 quote quote all
Where did you get those nice CF brackets from? Did you make them yourself?

Martin B

215 posts

80 months

[news] 
Friday 7th September 2012 quote quote all
When I made my fibreglass wing for my Clubsport, I bonded in some alloy plates in the lower half of the wing in the areas where the wing supports would go thereby giving the rivets for the external supports something to really bite into instead of just the fibreglass.




I probably over did the number of rivets but I didn't want it to fall off!

I also made the wing supports so all brackets were made to suit that.

LCM

436 posts

82 months

[news] 
Friday 7th September 2012 quote quote all
Good points you have made and I have been spending a lot of time thinking about the issues you have raised. First I had planned to simply follow this thread http://forums.bimmerforums.com/forum/showthread.ph... super fill the foam, use it as a core and wet hand lay the carbon fiber. Considering that the wing is 1700 mm long I was very concerned that having only a plain foam core would not be strong enough to withstand the load. Your comments that you have problems achieving a good bond between the foam and CF is an additional problem I have not considered. Are your bonding problems maybe related to the fact that you have not super filled the foam? I have been building RC pylon racers in the past. The wings of these race planes take tremendous loads and I was trying to adapt some of the RC building principles on the car wing.

Well, what to say? The vid is good on the wet carbon wrapped foam method but I think we should be cautious in comparing the loads that a poorly positioned wing on an E36 experiences compared with a well positioned wing on a sports racer. The wrapped foam technique is popular and succesful in the model aircraft world and my laminator has taken it up to UAV scale with success. The problem I guess is that the relative wing loadings on performance model aircraft may be high but are not on the same level as the absolute loads on a racing car wing. We used super-filled core and started with pre-preg fabric, but even wetting the core surface with resin the bond was not consistent and the cube law failed (depositing the testers who were standing on the wing onto the workshhop floor). We then tried a modified resin infusion technique but again could not get a good bond and low mass. If you can crack the problem then let us know as in theory it is a great technique for building low volume (even prototype) wings at low cost.

Building 4-5 ribs with a CF wing spar seemed the best solution to the problem but your idea of using a large diameter spanwise tube (what material are you using? CF?) seems even easier.

On an expensive, pre-preg wing it's carbon tube (readily available from stock). For a cheap wet lay wing it's GRP (cling film a suitable broom stick [even if it means that SWMBO is without transport for a day or so, but she can always talk to the cat eek] slap on some release agent and wrap wet choppy round it [topped and tailed with some nice tissue/cloth if you're feeling posh] cling film the outside like it's a boned and stuffed chicken leg about to go in the water bath and wait for it to go off).

[i]I still have not come up with a good solution to connecting the wing to the wing tower. I prefer not to use an external aluminium saddle but have not quite figured out how to do it.
I also do not have the right equipment to fabricate an aluminium end rib (it might have to be timber) to attach the wing end plates.[/i]

Yep, you've hit the problem. Because of the direction of the forces, the saddle works but knackers airflow for several inches either side, whereas an internal mount (PR6 style) requires some good internal structures between upper skin, (virtual) spar and lower skin. I normally accept the aero inadequacies of the saddle and bless its structural soundness.

There's nothing wring with resin infused plywood - refer to the late great Frank Costin http://en.wikipedia.org/wiki/Frank_Costin
http://en.wikipedia.org/wiki/DeHavilland_Mosquito

[i]In the meantime MVS has provided me a quote for a 1700mm CF wing and I must say adding up all materials and hours required to build my own their offer is almost too good to refuse.
Let's see what happens.[/i]

I'm assuming that it's Martyn's 230mm chord wing that he's quoted for. This is a good aerfoil section of the high camber/soft stall type and should work well on your car

By the way what else do you sell besides the gurney flap?

Wings (but normally these days pukka pre-preg fellas), stiff 4mm carbon/core/carbon rear wing end plate(RWEP) sheet, enhanced ground effect front under trays (FUT) for PR6/Prosport/Clubsport, Z strip for floor leading edge (single seaters or central tub sports cars like the Force LM), turbolators. Although if the mood takes me, I might do a new FUT for SR3/8 over the winter.

Edited by LCM on Friday 7th September 15:09

BioBa

Original Poster:

295 posts

38 months

[news] 
Saturday 8th September 2012 quote quote all
Martin B said:
When I made my fibreglass wing for my Clubsport, I bonded in some alloy plates in the lower half of the wing in the areas where the wing supports would go thereby giving the rivets for the external supports something to really bite into instead of just the fibreglass.
Yes I agree bonding in alloy plates to mount the bracket is easy, effective and makes perfect sense to spread the load.
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