Balsa/plywood Monocoque

[rjwoods77]

I was just thinking. Maybe another hair brained idea but... I am a big war history buff. Like planes,tanks,guns, etc. One of my favorite planes of all time was the dehavilland mosquito. Almost the entire plane was a balsa core and somekind of plywood or wood laminate skins. The thing weighed very little for the size of it for the day. Had a nice nice resin to hold it all together as well. Just figured the first person to do it would be real cool. Maybe one of the brit teams who do a carbon monocoque can look into this. Be cool if you did one since the plane is old school brit. Shit would be cool. I wish I was smart enough to do it myself.

[rjwoods77]

I was just thinking. Maybe another hair brained idea but... I am a big war history buff. Like planes,tanks,guns, etc. One of my favorite planes of all time was the dehavilland mosquito. Almost the entire plane was a balsa core and somekind of plywood or wood laminate skins. The thing weighed very little for the size of it for the day. Had a nice nice resin to hold it all together as well. Just figured the first person to do it would be real cool. Maybe one of the brit teams who do a carbon monocoque can look into this. Be cool if you did one since the plane is old school brit. Shit would be cool. I wish I was smart enough to do it myself.

[PatClarke]

Rob, In much more recent history ...Well in the late 1960s, there was a 1600cc Formula 2 car with a composite wooden monocoque, the Costin Harris Protos, driven, if I recall correctly by Brian Hart and Eric Offenstadt. Hart later became far more famous for his engines, Hart engines being used is most top line categories including Formula 1.
The car had uniquely slippery aero shape (this was before aero download) and was blindingly fast at fast circuits like Monza.
Warning: Warning: Warning: One of the cars suffered a major structural failure during a race and deposited the driver out on the track, so perhaps it wasn't such a good idea.
Glues have improved, though, over the last 35 years.
A Google search for 'Protos F2' should reveal some more information.
PDR


edit! Thinking about it, maybe the second driver was Kurt Ahrens.

[rjwoods77]

Very cool. I'll look into it. Either the glue sucked, or it was fabbed or designed wrong. Someone should really do it. I see video on the history channel of them making bulkheads and wing sections. Labor seems to be not that bad.

[flybywire]

Well, we've been using Gillfab paneling for a monocoque which has a balsa core with aluminium skin bonded to it. This has worked for many years and fabrication is basically "cut and fold". (We took the panels out to a company with a CNC router table to do the cuts.) I think the aluminium skin helps with the stiffness over a plywood/balsa only design. However, since we're cutting and folding already it looks like we're going to carbon for this year.

http://www.mcgillcorp.com/ makes a bunch of laminates for aerospace including the aluminium-balsa-aluminium one we've been using.

PS The mosquito rocked--well unless it was dropping bombs on your head--but what we really need are some of those WWII engines. http://fsae.com/groupee_common/emoticons/icon_cool.gif

[rjwoods77]

I was watching unlimited hydroplane racing one day about a year ago and I saw this one with the normal turbojet cowling off and this huge thing sticking out back. It sounded like a spitfire or mustang. It came around the corner and the camera had a stright on shot of it. Allison V-12(american built merlin/griffon) engine with twin turbos. Big turbos. I wet my pants. Coolest thing i ever saw and heard.

http://lynbob.4t.com/custom.html
http://www.kndu.com/hydros/boatinfo.src?ID=12

[John Bucknell]

Being in Detroit, we get to see these monsters up close. The giant turboshafts have to shut off about 2/3 of the way down the straight in order to get slowed down, and have to get back on it just after getting into the corner. Kind of hard to modulate.

The Allison boat didn't have those problems - even with the big turbos. Got of the corner quicker.

The biggest issue with running old warbird engines (same as unlimited planes at Reno) is there aren't many of them. The planes in particular were/are popping them like popcorn. In other sad news the Yankee Air Museum on Detroit's west side burned down last night - fortunately the warbirds themselves were saved (except some being restored). Lost many irreplacable artifacts, photos and books though.

[rjwoods77]

That sucks. Apparently U-3 owners were saying that even though parts are hard to come by, they are still cheaper to maintain than the turbojets. I have always wanted to go to the Reno Air Races. Those planes are just so neat. I grew up in Rochester Ny and my uncle used to work the Geneseo Air Show. They have a good show there. I was looking into doing a couple replica engines with a friend of mine. The concept is for them to look the same but with modern materials and design theory inside. One of the engines would be the allison/rolls v-12. I also would like to recreate(coolest engine ever) the brm 1.5l v-16 with the supercharger and everthing. But put fuel injection on it like they planned originally. The older iget the more i realize the asthetics a motor has beside just "how much power does it put out". Sound is everything. Its the real reason people buy cars. An electric or a hybrid wil do everything a normal gas engine will do but it doesnt have that sound. First thing I always do when I get into a sports car is to blip it to see what it sounds like.

[John Bucknell]

I'll have to disagree on coolest engine ever. Has to be Napier Nomad. Flat-12, two-stroke, continuously variable turbo-compound diesel with magnesium cases. Can only imagine what that sounded like.

The BRM motor (and crankshaft) I saw at the Donington Park Grand Prix Collection. Go there if you ever go to Formula Student.

[rjwoods77]

Oh yeah. Well, wait till we compete with our new motor. I promise you nobody has ever used one in a formula competiton. So there.

[Paul V.]

Monocoques can be made out of just about anything. Wood (even balsa) would be kinda far down my list. I was researching materials, and the most interesting idea I came up with was to sandwich aluminum sheet metal or fiberglass (Or CFiber if you must) between thick low density styrofoam. The glue is cheap and easy to work with. So is the foam. a hot wire will shape it any way you want. Stiffnes is excellent, its ultra light, and you can make a chassis for about $60-$100US. mega boost on cost report and most of the math behind it is explained in your mechanics of materials book. Everyone loves Hexcel, but its hackneyed and not the cheapest. Besides, I figure you want as small a closed cell as possible. I would like to inject and expand my own into a shell if I could guarantee consistency. You know everyone here in the land of NASA get mighty nervous around foam these days http://fsae.com/groupee_common/emoticons/icon_wink.gif. Let me know if you want numbers or info.

Paul
UAH FSAE

[rjwoods77]

Now that is consumer geared thinking. Sounds like a cool idea. Working with that would be very easy. I dont know enough about momocoque design as far as the pros and cons of various materials and shapes for the area in between the bonded sheets. Am i correct in assuming that it is better to not have all the hexagon cells inside instead of solid material if that solid material is super light like styrofoam? Why havent you done it yourself?

[Denny Trimble]

Rob,
I think your motor is on the opposite end of the coolness scale from the flat-12 John was describing. But I won't let the cat out of the bag...

And I've heard of one car entered at FSAE that had a very similar motor. Same company...

[Pat Clarke]

Hey guys, the word in Engine! Motors start engines http://fsae.com/groupee_common/emoticons/icon_smile.gif
And the engine John is referring to at the Donington Museum is a BRM H16 3 litre from about 1969, two horizontally opposed 8 cylinder engines, one on top of the other and in a common crankcase. Both banks had 'flat' single plane crankshafts, the top one 90 degrees out of phase with the bottom.
The inlets feed between the camshafts, so the engine has 8 induction trumpets sticking out each side, and 4 exhaust pipes each side top and bottom. I have heard the engine run, but unfortunately it was sick at the time and did not sound very impressive. I have some nice pix of the engine, if only I knew how to post them, but looking at it, it looks like the engine weighs about the same as an entire Oldsmobile Toronado http://fsae.com/groupee_common/emoticons/icon_biggrin.gif
Pat

[Avi Kagan]

Here at UNSW we've been running an aluminum monocoque chassis using an aluminum honeycomb core for the last 4 years. We've gone down this route for a couple reasons. One is the ability to build the chassis with no special tools or expertise. This is especially important at our school here since we don't have access to a student machine shop. It would also mean that you could manufacture these chassis using unskilled labor quite easily. Secondly we think it's a much safer structure than a steel spaceframe for the driver. We've done extensive testing, not with anyone driving if you were wondering, proving its effectiveness in a crash. There are issues however that need careful attention such as local stiffness and packaging considerations. This certainly was an issue with our first couple of monocoque cars ,and its taken us time to come up with a structure that adequately addresses all these issues. As for using a blasa core I cam across this paper while doing research on another topic. SAE Paper 2000-01-3539, Assessment of a Glued Aluminum Monocoque and Suspension for Formula Sae Style Racecars provides some insight into Queens processes for designing and building their chassis. I thought it was interesting to read. Good luck with your design.
Avi Kagan
2004 UNSW Technical Director

[BryanH]

Rob E. Woods, its already been done!!!
Bob Norwood built modern version of Merlin for Racing planes in I think mid nineties. Justin from haltech saw one being dyno tested, said it sounded awesome, much sharper than original engine. Don't remember power output. Price was est US$100,000
Bryan H

[Sisyphus]

The Marcos sportscars of the 1960's used a plywood chassis. Also Bruce McLaren used a balsawood/aluminum material called Mallite for his first Formula 1 car circa 1966--the one that used a sleeved down Ford V-8 Indy motor.

Re: "original" engines--I saw a 1.5 litre V12 on display at the Donnington Museum (a must see for gearheads!) in 1995. A British club racer built it up from a bunch of 125cc motorcycle engine barrels on a common crankcase and put it in a Lotus 23B circa 1966. Too bad there was no audio recording of it at full song!

[EliseS2]

I thought Mclaren used it first on thier Can-Am cars.

[John Bucknell]

So, I guess I'm curious. What kind of glues adequately bond structural foams to aluminum skins? Does that Queens paper describe it?

Pat's right I saw the H-16 3 litre motor. But there is this wall of crankshafts near the front of the museum that had the BRM v-16 crank. Itty bitty throws. They also had a Ford 1.5l F1 V6 turbo. Almost as neat as the the 84 BMW F1 engine I saw here in Detroit at McLaren Engines this spring (it's for sale if anybody is interested). Only 1400 bhp on 98% tolulene, with a turbo with a 6" inlet.

[Paul V.]

Metzger Door has developed an epoxy for making doors in the same manner.(3M probably has a ton of different compounds as well.) Thermo set glues are much more reliable, and more commonly used. A thin spray is light and bonds more than sufficiently.(the foam delaminates from itself prior to separating from the aluminum. I called an expanded polystyrene manufacturer when I thought of this and toured their plant. they Custom CNC'ed shapes and use thermosets to bond skins. They also made earthquake resistent walls in a similar process. I was astounded at the stiffness achieved. They placed a 12' panel across two cinder blocks, drove a Dodge Dakota onto it and there was miniscule bowing.


Paul Vaughan
UAH FSAE

[rjwoods77]

Sounds like someone should do one of these

[RacingManiac]

I believed our Canadian counterpart from Queens have been running a aluminum skin, balsa wood core monocoque chassis for the past few years now. 2004 I think produced their lightest car yet at under 400lb(with the use of composite a-arms as well if I recalled correctly...)

[Sisyphus]

The M2A and M2B McLaren's used Mallite (balsa wood between aluminum skins). The torsional stiffness was claimed to be 10,000 ft-lbs/degree which was probably the stiffest open cockpit car built until carbon fibre chassis came along........the MP4 McLaren.

The first McLaren's M1A, M1B...were conventional tubular space frames. The M6 was the first (aluminum) monocoque.