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this is a serious question
pedromorgan - 31/5/05 at 09:30 AM

although it may not sound like it!

has anybody considered bolting a plank of wood to the bottom of their locost to improve tortional strength?

peter


JoelP - 31/5/05 at 09:57 AM

most wood would be too flexible to make any difference, even good ply. How thick were you thinking and what material? it would, however, be good to prevent the car scraping on stuff, F1 style!


nick205 - 31/5/05 at 10:08 AM

Like Joel says, can you expand a bit more on what you have in mind?

Nick


pedromorgan - 31/5/05 at 10:09 AM

i was thinking about 1 inch oak about 10 inches wide. it would add a good 20-30kg's but is seasoned correctly it would be incredibly stiff.


Peteff - 31/5/05 at 10:18 AM

Make a nice shelf with it and put some more metal in the chassis if you're worried about flex. There are lots of standard chassis on the road and they've not turned into bananas yet.


nick205 - 31/5/05 at 10:19 AM

I suspect you could achieve better results for less weight by building in more chassis tubes (steel).

Also wouldn't the wood eventually absorb moisture and hold it next to the steel chassis or ally floor, speeding up the inevitable corrosion process?

Just my thoughts!

Nick

PS - how much would a chunk of Oak like that cost?


pedromorgan - 31/5/05 at 10:19 AM

no i havent had any problems. i havent actually started building it yet but i know others have noted that the book chassis is not fully triangulated and i dont believe it can be as there is an engine in the way.

i want to do a book chassis and put morgan styly bodywork on it with full length running boards in a nice BR green or maroon. so performance is not really the greatest of issues but ride comfort and safty make up for it.

peter


pedromorgan - 31/5/05 at 10:21 AM

oak is sold but the square food so £20 per sq foot 8 foot by 1 foot = £200


Peteff - 31/5/05 at 10:29 AM

That much would build you the chassis, you'd think of doubling the price for the dubious benefit of bolting a plank to it?


pedromorgan - 31/5/05 at 11:25 AM

well if you think about it. people are always going on about carbon fibre for strength. all carbon fobre is is synthethic wood. the sings on wodden kit planes are often strong enough for one side to be bolted down and a person to walk along the other side in mid air. i think there would be conciderable benifits to this idea but i dont know if it would be a better idea than doubling up a few of the pipes.

peter


nick205 - 31/5/05 at 11:29 AM

IMHO a the plank would be better cut in 2 and made into a nice coffee table top.

Pedro - you say you're planning a locost with morgan style bodywork. Is it the Morgan connection that got you thinking about using wood? I'm sure I remember reading that Morgan built their chassis out of wood somewhere.

Also you should look at Steve Gusterson's build as he is doing something very similar.

Nick


pedromorgan - 31/5/05 at 11:37 AM

it is partly the morgan connection that got me thinking seriously about it. but i remember there was a programme on telly about 5 years ago about someone building a plane in 30 days and almost the entire plane was built from plywood and fabric skinned. they were constantly doing things to demonstrate how strong it was. i know a wodden geodesic framework would be incredibly strong. i just have never seen a car made of wood before. howard hughes made the spruce goose from plywood.
not on this car but on my next one i would like to cover alot of the body with veneer, especially the boot to give it a 'riva powerboat' look.

peter


ned - 31/5/05 at 11:54 AM

lookup locust and chitty chitty bang bang for cars made of wood


pedromorgan - 31/5/05 at 11:59 AM

i knew somebody was going to bring up chitty!! i didnt know about the locust pages though. thanks for that one.


DaveFJ - 31/5/05 at 12:03 PM

if used in the correct way Balsa is one of the strongest hardwoods available. It is actually used in the construction of some sky scrappers !!


craig1410 - 31/5/05 at 12:10 PM

I know F1 cars have a "plank" under the car but I'm pretty sure it ain't made of wood!!!

Cheers,
Craig.


DaveFJ - 31/5/05 at 12:15 PM

quote:
Originally posted by craig1410
I know F1 cars have a "plank" under the car but I'm pretty sure it ain't made of wood!!!

Cheers,
Craig.


Actually it is..... it is there to prevent them from lowering the car too far . at the end of the race the srutineers inspect the plank to ensure not too much has been worn away during the race......


Bob C - 31/5/05 at 12:15 PM

Sure wood's good stuff but a plank is the wrong shape. If you put one end of the said plank in a vice & tried to twist the other end by hand you'd easily get several degrees of twist into it. You're aiming for several THOUSAND ft lbs per degree so it's one or two orders of magnitude away from helping! It's also isotropic & variable. I'm going to stay with iron. BTW the wood frame in Morgans is a frame for the bodywork AFAIK, not the main chassis.
Bob C


pedromorgan - 31/5/05 at 12:18 PM

i think it is made of wood actually. it is not structural though it is regulatory. it was brought in buy the FIA to stop the cars running too low. it is measured after the race and if it has worn down too much (i think it starts at 12mm think and i think, it has to be more than 8mm by the end of the race). then he is disqualified. i think it happened a couple of times when it was first brought in but i havent heard anything recently. i tink it was one of the 'Senna' modifications.


pedromorgan - 31/5/05 at 12:25 PM

"The Morgan car has always been built around an ash-frame , and a steel chassis. The new Aero 8 also has an ash frame. This gives unique strength, flexibility and surprisingly, research showed that the frame made the car safer on impact tests. "

from morgan web site
i think the point is that the ash body framework takes a large portion of the total load.


nicksertis - 31/5/05 at 01:07 PM

If you're after some more rigidity in the frame, I think aussie builders need to modify their chassis to get it to comply with stricter guidelines there? Might be worth having a look at the Australian yahoo forum and see what solutions they have come up with.

Cheers,
Nick


James - 31/5/05 at 01:40 PM

This thread's been here for 4 hours and no-one's mentioned Cymtrics yet!

Pedro, forget wood in this application. Search for the posts by Cymtrics whose done an FEA study of the chassis and has published plans of how to double the torsional stiffness of the chassis for minimal weight gain.

As for the plank in F1. Wood is a little too kind a term for it- it's plywood I believe. A high density resin/wood mixture.
Some may remember that Schumey had a little trouble with his in about 2001.

Cheers,
James

[Edited on 31/5/05 by James]

[Edited on 1/6/05 by James]


theconrodkid - 31/5/05 at 01:55 PM

(murray walker voice on)and shoey is in the pits,he,s got woodworm and the mechanics are searching for the cuprinol...oh no its termites


DaveFJ - 31/5/05 at 02:04 PM

Just to be a sad geek - again.....

quote:

3.13 Skid block:
3.13.1 Beneath the surface formed by all parts lying on the reference plane, a rectangular skid block, with a 50mm radius (+/-2mm) on each front corner, must be fitted. This skid block may comprise more than one piece but must:
a) extend longitudinally from a point lying 330mm behind the front wheel centre line to the centre line of the rear wheels.
b) be made from an homogeneous material with a specific gravity between 1.3 and 1.45.
c) have a width of 300mm with a tolerance of +/- 2mm.
d) have a thickness of 10mm with a tolerance of +/- 1mm.
e) have a uniform thickness when new.
f) have no holes or cut outs other than those necessary to fit the fasteners permitted by 3.13.2 or those holes specifically mentioned in g) below.
g) have seven precisely placed holes the positions of which are detailed in Drawing 1. In order to establish the conformity of the skid block after use, its thickness will only be measured in the four 50mm diameter holes and the two forward 80mm diameter holes.
Four further 10 mm diameter holes are permitted provided their sole purpose is to allow access to the bolts which secure the Accident Data Recorder to the survival cell.
h) be fixed symmetrically about the centre line of the car in such a way that no air may pass between it and the surface formed by the parts lying on the reference plane.
3.13.2 Fasteners used to attach the skid block to the car must:
a) have a total area no greater than 40000mm² when viewed from directly beneath the car ;
b) be no greater than 2000mm² in area individually when viewed from directly beneath the car ;
c) be fitted in order that their entire lower surfaces are visible from directly beneath the car.
When the skid block is new, ten of the fasteners may be flush with it's lower surface but the remainder may be no more than 8mm below the reference plane.
3.13.3 The lower edge of the periphery of the skid block may be chamfered at an angle of 30° to a depth of 8mm, the trailing edge however may be chamfered over a distance of 200mm to a depth of 8mm.


britishtrident - 31/5/05 at 04:38 PM

quote:
Originally posted by pedromorgan
although it may not sound like it!

has anybody considered bolting a plank of wood to the bottom of their locost to improve tortional strength?

peter


What matters is torsional stiffness not strength and a plank of wood oak of the diminsension mentiond isn't very stiff in torsion.


britishtrident - 31/5/05 at 05:02 PM

quote:
Originally posted by pedromorgan
"The Morgan car has always been built around an ash-frame , and a steel chassis. The new Aero 8 also has an ash frame. This gives unique strength, flexibility and surprisingly, research showed that the frame made the car safer on impact tests. "

from morgan web site
i think the point is that the ash body framework takes a large portion of the total load.


I cut my teeth on MG T types so know a thing or two ash frames and seperate chassis --- believe me an ash frame can't take impacts particularly after it has been around a few years.

Every driven a Morgan ? call me Mr Wippy but having driven crawled under and repaired them I can say it ia triumph of shear of the dog headness of the late Peter Morgan to carry on every single one his fathers mistakes over any semblence of engineering common sense.

If you want to build a Morgan replica the chassis dead simple much simpler than a Locost ust 2 lengths of "Z" section running parrallel and at the front a crossmember to support the ends of the sliding pillars a bulkhead assembly in the middle and thats it. A Morgan is really just a big a tunning fork made of "Z" section no other motor manufacturer ever used "Z" section to build a chassis because it has truly strange deflection properties.


Wadders - 31/5/05 at 05:13 PM

if your going to put a morgan stylee body on, why waste your time building a book spaceframe chassis? why not make life easy for yourself and use 3 x 2 box section to make a ladder frame chassis, which will be plenty strong enough, and allow you to have opening doors, jag suspension all round to give a comfy ride, Rover v8 upfront. luvverly!
Save the wood for the dash and door tops.

Al.


britishtrident - 31/5/05 at 06:00 PM

Plus 4 Plus 8 4//4 trad Morgan chassis Rescued attachment chassis.gif
Rescued attachment chassis.gif


Wadders - 31/5/05 at 06:08 PM

Are you sure thats not a Silver Cross chassis



Originally posted by britishtrident
Plus 4 Plus 8 4//4 trad Morgan chassis



craig1410 - 31/5/05 at 07:27 PM

Oh well that serves me right for being a smart ar$e eh???

I just assumed that the fact that sparks fly off the underside of the F1 cars when they scrape across the ground was an indication that the "plank" was made from a metallic material. I guess it's just the fasteners that scrape on the ground then? Anyway, I still find it hard to accept that the F1 cars drive around with a big lump of wood strapped to the bottom of the car, surely something more exotic is in order in the high-tech world of F1... Then again a lump of MDF is quite handy for many things I suppose.

Cheers,
Craig.


Paul_C - 31/5/05 at 09:35 PM

An old quote from Motor written by Henry Manney described Morgans at a 1960s Motor Show as a fine collection of early Saxon artefacts. Though I now quite like Morgans, premature senility.
I believe that the F1 skid plates are Jabroc (densified wood laminate).


Mark Allanson - 31/5/05 at 09:58 PM

... the "plank" was made from a metallic material........ In the early 90's they had titanium skid plates.

Rather than strapping a bit of tree under my car, I would like to have spring loaded arms with titanium tips to give the 'mansell spark shower effect'!!


craig1410 - 31/5/05 at 10:08 PM

Thanks for that Mark, I remember fondly watching Mansell, Prost and Senna slugging it out amongst showers of sparks and I couldn't see how such a shower of sparks could result from the fasteners on the plank alone. I guess they must use different materials today as the sparks seem less prominent although from the F1 rules I don't think they have to use wood. They seem to be allowed to use other materials provided the density is within the specified limits.

Anyway, I agree that there are better routes to a stiff chassis than strapping a chunk of oak to your chassis...

Cheers,
Craig.


mcig68 - 1/6/05 at 12:03 AM

On the same topic but a different problem. Doesn't steel corrode quicker when in contact with oak? Something to do with the acids presesnt in the wood.
It also tends to deform in an impact into large and very sharp pointy bits. A bit like barbecue skewers!!


kb58 - 1/6/05 at 01:39 AM

That's what killed so many crewmen back when they used solid (non-exploding) cannon balls. The impack of the ball on the oak planking sent 100s of "splinters" flying. I put that in quote since most of them were about 12" long!

I got to see a video where they fired a real cannon and a real cannon ball at the oak siding of a simulated ship. They even put dummy crewmen on the other side.

Amazing damage that...


pedromorgan - 1/6/05 at 09:43 AM

i dont really want to build a ladder chassis. unless it is precisly manufactured and integrated with the body i think they have appauling crash worthyness. also i am really after a nice car and not necesserally an easy car.

as for the morgan bashing, they had to be thoroughly crash tested to be type approved in the USA so they cant be that bad. i think they typify an elegance that virtually no other car has come close to. they are the sort of car you would like to take a posh girl to the theatre in.

going back to the origional question, i hadent seen cymtriks's posts untill now and found them very interesting. i cant remember who pointed them out but thanks to whoever it was.

i still think an oak plank would be incredibly strong (yes even in tortion) a piece of well seasoned oak is extreamly hard and stiff that is why they uase if for roofs. it would be impossiable to put a nail into a piece of 2 year old oak withought drilling a pilot hole first.
however i think the benifits would not be as great as cymtriks's findings.

thankyou to all those who posted.

peter


craig1410 - 1/6/05 at 11:54 AM

Peter,
Yes seasoned oak may be stiff but it's never going to be as stiff, weight for weight, as steel and steel is a lot easier to join together than wood, especially when you consider awkward compound angles.

Cheers,
Craig.


kb58 - 1/6/05 at 02:27 PM

It's simply way too heavy for what it does, versus steel and/or aluminum.


cymtriks - 1/6/05 at 04:56 PM

quote:
Originally posted by Wadders
if your going to put a morgan stylee body on, why waste your time building a book spaceframe chassis? why not make life easy for yourself and use 3 x 2 box section to make a ladder frame chassis


Use 4x2 - 14 gauge, lighter and stiffer.
3 x 2 isn't very good as it's overweight and understiff by comparison to 4x2 in either 3mm or 2mm (14g).

Regarding using an oak plank. Don't.
This just isn't a sensible way to stiffen up the chassis or to use up a nice piece of wood.

My chassis mods ( check the double Y braced frame in the pictures section and read kitcaranalysisV2.doc on locost7.info) will more than double the stiffness while saving a bit of weight.

The best wood to use for a chassis is plywood. This can be very good as some of it's properties, weight for weight, are as good as some very exotic materials and it's a fraction of the cost. The problem is joining the sheets together effectively. Possibly the best way to do this is to use the plywood to reinforce a fiberglass monocoque. This could be a very cheap way to get a very good result.

In fact spruce spars, as used on very early aircraft, are as strong and stiff for their weight as steel but the problem is joining them together, all sorts of complex plates and gussetts are required as detailed in early aircraft design books, with steel tubes all you need is a saw and a welder.

But don't use an oak plank. It's not a good idea!


fester - 1/6/05 at 05:48 PM

quote:
Originally posted by pedromorgan
i dont really want to build a ladder chassis. unless it is precisly manufactured and integrated with the body i think they have appauling crash worthyness. also i am really after a nice car and not necesserally an easy car.

as for the morgan bashing, they had to be thoroughly crash tested to be type approved in the USA so they cant be that bad. i think they typify an elegance that virtually no other car has come close to. they are the sort of car you would like to take a posh girl to the theatre in.

going back to the origional question, i hadent seen cymtriks's posts untill now and found them very interesting. i cant remember who pointed them out but thanks to whoever it was.

i still think an oak plank would be incredibly strong (yes even in tortion) a piece of well seasoned oak is extreamly hard and stiff that is why they uase if for roofs. it would be impossiable to put a nail into a piece of 2 year old oak withought drilling a pilot hole first.
however i think the benifits would not be as great as cymtriks's findings.

thankyou to all those who posted.

peter


fester - 1/6/05 at 05:57 PM

Peter;
your point about Morgan crash testing is taken,but torsional rigidity does not rely upon strength in one plane. Steel box section ladder and space frames (when correctly designed and triangulated) far surpass wood weight for weight . They also have the added advantage of ductility,so (if you wrap one around a tree,hope you dont) a large part of the impact will be absorbed by distortion.


Paul_C - 1/6/05 at 08:14 PM

Wood has been successfully used in chassis such as various Marcos's and other models designed by Frank Costin (I particularly like the Amigo). The stiffness to density ratio of wood is comparable to steel and aluminium. I don't know what the crash performance is like but any light weight car isn't going to be great. I don't believe that the 1 inch box section is all that good. My reservations are based on wood not liking hot exhausts and heavy point loading like engine and suspension mounts. They would probably benefit from sub frames negating the advantages of the light material. Also the mechanical properties can be rather variable so if a critical part of the chassis coincides with a defect in the wood then life could be exciting.


Rorty - 2/6/05 at 04:52 AM

quote:
Originally posted by James
This thread's been here for 4 hours and no-one's mentioned Cymtrics yet!

James, are you inferring Cymtrics is a plank? I know some of his notions are a bit off the wall, but that's going a bit far isn't it?


Rorty - 2/6/05 at 05:12 AM

Morgan (and other wooden chassis) only work because the timber sections are relatively small. It's virtually impossible to 100% seal wood and inevitably, moisture will get in. That done, a 300mm wide plank of oak will expand and contract across its width by about 6mm. There would be absolutely no point in using a seasoned plank (unless the car was going to be driven only on dry sunny days), because the first time the car went out in high humidity, the plank would start to swell.
If the plank were confined within some of the chassis elements (as opposed to being just screwed on), it would have the strength to burst the chassis apart. Moving timber is very powerful. Have you ever wondered how some of the ancients used to quarry their bloody great blocks of stone? In cold climates, they would use fire to create cracks and then wait for winter to freeze the water in the cracks to burst the rock apart. In warmer climes, they would hammer bone-dry wooden wedges into cracks and then pour water onto the dry wood which swelled and broke the stone apart.
The acid in oak (and to a lesser degree, in most other trees) referred to above is tannic acid which reacts with iron when damp, turning it a deep blue-black (basically,how early ink was made).


kreb - 2/6/05 at 06:32 PM

I agree that a plank sounds frankly silly, but I have been amazed by the properties of marine plywood sandwiched in Fibreglass. I've built a kayak using "stitch and glue" construction that's 16 feet long, 40 lbs. and can withstand "aguering" with a 225 lb. lump aboard (me) Use of this product in place of aluminum might well have aesthetic and strength advantages. Interestingly, I noticed that the LMP has plywood floors as well.


craig1410 - 2/6/05 at 06:42 PM

Yes Steve Turner was round at my house last night and mentioned that the LMP uses 6mm marine ply on the floor. He has tried aluminium in the past but settled upon the plywood as a lightweight, strong, cost effective and easily replaced alternative. He said there are better alternatives but these are too expensive to be practical in most cases.

Cheers,
Craig.