I know this has been discussed a lot lately but all the folks doing them lately seem to be keeping most of the original wings, which i'm not fussed about

I need to build tubed wings for the 90 - the 110 is getting them too but I'm trying to pay someone to do those - I dont really mind about chopping the front of the car up, and I would rather have ultimate strength rather than keeping the Defender looks

Below is a couple of back-of-the-snap-on-reciept sketches I did with the wax crayons last night, can anyone spot any obvious flaws with either of them, and can anyone recommend one design over the other, or where to add gussets/tubework?





Cheers

Lewis

my concern with both would be a hit on either wing bar will affect the other side
transferring the force across the front support bar.

If you are keeping it road legal then you need to consider lights (or a daylight only MOT). The top design, which I like best, makes it more tricky, still doable (look at the like of Bob Seaman's truck - I think that's right) just needs a bit more thought/work.

I would say Mr Bish is the expert on this.

But my 2p worth is that given the front end or either side of the front end has a really good thump, the forces are going to bend the roll bar down tube as it is mounted high up and on its own.

Wheel travel allowing I would say add an extar tube to the centre part of the wing bar top and take it to the base (or low) to the roll bar down tube, this triangulation would add a mass of strength ?

nige

There is no simple or absolute answer to this because it depends on the direction the forses are applied to the frame.

There is a lot of mileage in building a model out of straws, glued together. Try pushing in in different places to see how it resists movement.

Design A in this instance will give the greatest resistance to being pushed sideways. It would benefit a lot from a vertical joining the tube above the radiator to the top of the chassis rail on each side to form a triangle.

Mine looks like B, but with a diagonal from the corner to where the steering box bolts to the chassis, triangulating in two planes - and it has proven exceptionally strong!

Si

Mark90 - Bob seamans, Justin deans and Rog's (898Kor) trucks have been inspiration for design A. DirtyDiesel built Bob Seamans wings and recommended design A for the 110 - which he will hopefully be building. Design B was borrowed blatantly stolen from SimonR's truck

HFH, SimonR, do you mean like this or have I misunderstood?



SimonR - have you had any issues with strength on your vehicle? And could you be so kind as to reinstate the photos of your build on sprocklegrommit, so that I may peruse them some more. Cheers

Not quite what I, at least was suggesting.

This is what I meant:


I would reinstate the photos on Sproklegrommet, however, all I have are the thumbnails. The masters were on a photo-hosting site, now no more! Guess many are gone for good!

In the above design, the bar in front of the rad un-bolts to make engine removal a bit easier. The wings are entirely bolt-on (just in case one gets squashed!).

In terms of strength, I have rolled the LR such that the weight of the vehicle was supported on the front corner of one wing and the rear of the cage. Plus, I have leaned on trees & rocks as hard as I can against the bars and nothing has moved!

I decided not to tie it to the bumper as it is most likely to be bent and I didn't want it to bend the wing in turn. The wings finish above the bumper so it can fold underneath.

Si

Thanks Si, I see what you mean now. Not attaching direct to the bumper sounds like a good idea

Simon is a wise man - triangles are your way forward.



Before I comment on the wing bars, can I first say that the first tube you add to your vehicle should be a diagonal brace in the roof of your cage. Front to back tubes are all well and good for fending off trees and end over end rolls, but you need triangles in all planes of your cage to get maximum strength.



The screen bar is a good addition.



Right, moving on….


Design A is the better option for strength. Triangulating to the bulkhead outrigger will improve your tube strength in the vertical plane (and improve buckling resistance from a head on hit) a bit but it does potentially move the weak point to the outrigger that would be loaded out of plane. (front to back) Personally I would rather repair a tubed wing than an outrigger…

Tony is right that having the two sides connected means you risk damaging both sides in a bump, but on the other hand, having both sides joined means that you benefit from not damaging one side in a lesser bump because both sides resist the impact. Six and two threes in my opinion unless you can determine the magnitude and frequency of your bumps!



Design B can be made as strong as A using Simon’s method. I think aesthetics really differentiates between the two designs.



Try an envisage at least one triangle in each plane that the assembly can be loaded. Ideally, you would want a diagonal across the engine bay, but that might cause other issues!!! Next best is to take the loads diagonally down onto the chassis rails from the front corner of the wing to a point on the chassis rail around the steering box position (à la Simon R)



My 2p.

Thanks Bish, no end of help

The crayons have been out again, what do you all make of this? And have I missed anything?



I'm not sure you can tell in the drawing but I've tried to keep the tubes to one peice where possible, mostly because I'm lazy but also because I cant weld very well and want to reduce the places where i'll make it look perform sh*t

I personally wouldn't bother with the brace to the outrigger and from the outrigger to the chassis. You are better off bending the wings than the chassis.

to improve the front to back stability take a diagonal from the top front corner of the wing diagonally back and down to the chassis This will also help prevent the front hoop of the cage getting out of plane forces on it.

I'm not convinced about the bracing back to the cross member - but for a different reason.

I built the model out of straws - almost exactly as you have it there.

If you push hard enough on the front, the outrigger is so well held in place that the diagonal bar rotates around the end of the outrigger. This puts a shear load on the weld where the wing bar joins the front hoop. If this breaks - that tube enters the cab!

If you loose that diagonal, the vertical of the front hoop bends instead, directing the wing bar downwards - but more importantly absorbing a lot of the impact energy.

One of the most important things in a cage design IMHO is that when it is loaded in the way it is most likely to be, if a weld should break, the bits move away from you.

The front will be good & strong. I moved the connection point of the diagonal down the the chassis down a bit from the apex of the corner to allow me to fit a standard headlight in the standard location. It also gives a void behind where the indicator and side light normally live.

I appreciate the concern about relaying forces from one side to the other via the radiator bar. However, most of the impacts are going to be fairly light and this method reduces the likely hood of it moving. In an impact capable of moving both sides - you probably have more important things to worry about (like the cleaner unplugging your life support by mistake!).

Si

PS Cheers Bish - Cheque in post!

Okay, here goes



Somefink like that?

Thanks

Looks about right to me.

Not based on any experience or knowledge , but it struck me when looking at Tony's and James bars that wouldn't it be easier/stronger to add outriiggers to front of chassis and bring bars down to this rather than bumper?

Cheers

Steve

The bumper connection on James and my own is with small bolt
the is meant to be a fuse if a big hit on the bumper occurs.
but the connection also stops trees getting in between the bumper and wing, I've had this twice recently, damaging the wings both times.
an outrigger on the front would need a fair amount of bracing this may foul the wheel on full lock, given there isn't much room in the engine bay
thats why we chose behind the headlight for the support brace.
Time will tell I guess.

Strength aside would it not be easier to fit side panel and eyebrow to design B rather than A (which in skeleton form I prefer)?

the theroy i had in my mind when making the ones for ours was that the current wings were only ali and got bent from brushing against trees, i intend to drive with the same due care(!) but now with the bars fitted the sides shoudl be protected, rather than drive smashing into things because i have the bars, i would also the bars bent rather than the chassis. just my thougths. as Tony says time will tell.

This was the reason I did mine Just to take the brush damage away from the soft ali wings , Dont plan on knoking any trees over just yet ,
When I built mine I made them strong enough to cope and weak enough to eliminate knock on damage, A bit of a crumple zone if you like.It could make the difference of damaging your wings or getting thrown through the screen .

that makes more sense to me, it also saves weight

the other would be why follow the standard wing profile?

The only problem i would have with lightwieght designs or those with a fuse. Is that in the event of a roll like lewis's You'd probably still be too heavily damaged to carry on the event, whereas if you take the sherman tank type of design you get to carry on regardless and the only trees you've got to watch out for are the 400 year old oaks


Re-design A floats my boat the best.




















Durrr.... so other luddites still accept them

nice to see you've finally woken up

cut the weight out of the top end and be less likely to roll in the first place?



panzer boy....

Yes it would, and if I was intending to keep the defender "look" then I would probably look at those a bit more, but changing the wing design isnt a concern for me, I care more for strength and longevity than aesthetics

I wouldnt say that I want to use them as i ramming tool, just that it would be nice to have a driveable car if it happens accidentally Plus keeping the car moving mid event after a roll like last sundays is a high priority for me with the 110, and fending off careless drivers on the streets of coventry in the 90 would be nice

Which one Dan, the first or second?

Lewis

The first one.

For my 2pence worth as an automotive structural designer, there are two options, a, do you wnat the tree bars to be absolutely solid and assume they are just tree bars, or b, are you looking for some deformation inan impact to prevent the full pulse from being passed onto yourself.
Due to the nature I would assume 'a' is the direction you're aiming for in which case I would go with the first of your two sketches but would make use of some tubular front shock mounts which would attach to the two upper bars and down to the chassis, with the shock mounts suspended bellow the cross brace between the two top bars.
If you wanted to go the whole hog and get a little indepth I could model the options in CATIA and run them through the analysis program to let you know which performs better. ( the more technical version of Simon's straws )
I would be tempted to look at the Raid Rally cars for their bracing ideas, Tomcat ( obviously my personal favorite ) and Wildcat pictures are all over the net, but if you can't find any I can get a wing on the Tomcat and take a picture. It is more simple than my suggestion and still incredibly robust, just the fibreglass which lets it down.

On the 110 the shock towers are 4 inch box welded vertically above the spring cups on the chassis with the shock running inside, these could easily be modified to tie to the wing bars


Yes please, that would be great if you have the time? I would be very interested in how much deformation the wings and cage would see during a strong frontal impact at 45degrees to cars longitudinal, i.e. hitting a car tree with the corner of the nearside

The photos of the tomcat wing would be great if you can get them?

Cheers, Lewis

Tomcats are actually very simerlar except they have their wing bars under their skin.

Lewis, I think you're design is nearly there. As Bish said, triangles are good. I know some people will suggest having a setup that will deform quite easily I believe that defeats the main reason for going for a tubed front end. However, they do have a valid point that you don't want to have points that will build up massive stresses in a big impact; flailing tubework is not a good idea! The way to get the best of both worlds is to ensure that the loads are spread evenly over as wide an area as possible. Remember now you've got wingbars on top of a cage you've effectivly created a space framed vehicle - the bodywork is only filling in the gaps!

Lewis will model up the frames over the weekend if I get a chance, will take rough dimensions off the Tomcat, unless you want me to specifically use your measurements, should be able to give you an idea of how it looks by next week, my email is mark980@btinternet.com if you have anything dimensions wise you particulary wanted to use. The chassis rails will be a little vague as laziness and ease of measuring them will probably prevent me getting them too close, but will treat them as rigid beams which don't bend in the impact probably anyway.

Will is dead right on the impact front, all the front end will only be as good as the weld, and would not like to see the welds to the a post breaking loose and coming into the cab...

Thanks Mark thats great, I'll go with your dimensions for ease if thats okay? Not being an engineer I wouldnt know which measurement would be applicable

Lewis

Now i'm no expert but surely the brace across the roof on the cage should run the other way above the driver, just like a single diagonalbrace for a hoop always has the top above the driver?

Expert? No nor me, but as I'll be sitting on the passenger side then I'll have it this way round

Lewis, the model is not quite finished will aim to get it completed today if we are quiet in the office. In the mean time here are some pics of the Tomcat set up, which as I said we use for winch challenge events and gets bounced off trees and rocks fairly regularly.

Oddly Nope, Bish is correct

MSA Section Q attched showing diag top brace drivers rear to passenger front !

Right here you go front end 3/4 impact direct onto corner of vehicle, impact evenly distributed on the corner. Slightly vague analysis as have just built the cage and assumed rigid fixings to the chassis ( chassis does not move in the impact at all ), vehicle impact is 7 mph with a 2000 Kg car, impact is based on 65000 N against a tree which will only permit a 0.05 M deformation ( hard wood worst case ). However that is all reasonibly immaterial as we are looking at a comparison analysis between the designs. All deformation is subject to a 20 times magnification to make the bend visible, real numbers are shown on the displacement vector graph on the right hand side of the images. Have also included the force diagrams so you can see how the load is distributed through the frame.

I have not included a roof cross brace, but would say the brace only functions in support of the system down the length of the tube, if impact is from the other front corner the brace will actually slightly weaken the frame as it will promote locally maximised stresses encouraging the frame to deform, so would put a cross form going front to back diagonally from both front corners.

I will post the images up seperately following as otherwise it will be hard to differentiate the different results.

Basic original design.

First image shows design, 2nd shows forces, 3rd shows deformation

Radiator bar cross linking the two sides.

this is modeled as welded in which may or may not be possible depending on engine etc.

screen bar included.

damper mount reinforcement.

Then of course there is the analysis utopia, although in reality less than practical, but could be a removable section if the engine was low enough. The deflection drops to a tiny 1mm deflection

Then of course there is the analysis utopia, although in reality less than practical, but could be a removable section if the engine was low enough. The deflection drops to a tiny 1mm deflection

Then of course there is the analysis utopia, although in reality less than practical, but could be a removable section if the engine was low enough. The deflection drops to a tiny 1mm deflection

Hi All,

Dy'all mind if a newbie chips in?

Although i'm a posting newbie on this 'ere forum (one or two of you will know of me from elsewhere) i've been observing for a while and been watching the two wing bar threads with especially keen interest.

I thought i'd break my silence to ask the generous Markwindsurf if he would be so kind to repeat his virtual test with an idea of wing bar design i have. If you can let me know if that would be ok Mr...er..Windsurf?

thanks
Pete.

Welcome Pete
we were all new once

And Mark these posts make this site what it is
full of interesting/helpful members.

excellent work IMHO

Pete, No problem, post up a pic or description of your idea and will have a go at modeling it up and running a comparison against the others. Will try and get into it tomorrow depending on how busy the office is.

And white 90 thanks for the feedback.

It really warms my heart to see people prepared to go that extra mile to help others on company time


Seriously, like Tony says it's what makes this place

Thankyou Mark for modelling the designs, it really helped me to understand where the deflection occurs with the impact. I hadnt realised that the front hoop is made to take so much force. Looks like I'll be trying to find a way to implement the cross engine brace

Thanks again

That all looks impressive, but....
Are you guys planning a bankrobbery? Thats just way overkill imho.

Daan

How did you guess
Overkill? - no way, just well prepared

We need all the strength we can get - You havnt seen my driver drive (neither have I come to think about it)

Thanks Mark,

i'm not so good at trying to describe it, and i dont have a scanner to scan in a drawing. Presumably if you have that kind of programme at work you would have something as simple as Autocad? if so can you ping me your email add. and i'll send you a cad file of it. unless you know of an easier way of course.

pete.

Lewis, I am actually with Daan in this case, going back to my intial comment if you make the cage too strong it does not do what the cage is designed for which is to reduce the shock passed on to driver and passenger, at 7mph not too much of an issue but at 30 much more of a problem although obviously the frame work deform differently at that speed.
Had some time last night so had a little play and will attach it in a moment which might be a more useful / workable solution

Note of caution
Also in my opinion the hassle value of the cross brace vs benfit would prevent my fitting it, don't forget the brace was modeled as a welded part so some strength would immediately be lost when you bolted it in. The bolt joints would concern me at the bulkhead end, in the case of a hard front impact shearing the bolts and driving the frame through the bulkhead. I would need to be very confident that the impact could be deflected from me and the passenger before even considering it.
Also I have just analysed 1 loadcase ( although probably the most likely ) the other impacts I find in competition we sustain is a good knock on the tree bars on the roof and a backing out impact to the rear stays, hence why my roof tree bars now go all the way from the screen to the rear corner, which also means we never get hooked up on trees.

Daan, the anlaytical utopia is not always the most practical solution, but it is always interesting to take the development to the extreme just to see what actually happens in the structure, and putting it up may spark a comment from someone suggesting an alternative that I might not have considered.

Mark