Teardrop calculation

[OLDPOP]

Bob

Like cousin Alberts formula

how many cartons to build a Falcon like yours
all other formulas sound very complicated

Regards Oldpop

[ben james]

dr goggles, could you elaborate on your last post

[Dr Goggles]

dr goggles, could you elaborate on your last post

Ben , people are interested in that stuff , trust me................

[gennyshovel]

Therefore, if you travel along way,and drink alot of beer with some old mates,it don't matter that you broke the motor,you still enjoyed yourself!

Well put Bob , I might add,,,,,
Teardrop =a small pool of body fluid oozing from the eyes after discovering a failed bigend bearing halts my plans for the meet

[Rob]

Hey, I'm interested. I've got one (small) tank sitting here and am looking for a larger one!

Thanks Doc,

That may have been where I was reading it in the first place. I guess I should buy and read both books to edificate myself some more.

Tank looked good btw, somehow I managed to miss every run.... yours, the Revrund's and Al Fountains.

Rob

[grumm441]

Therefore, if you travel along way,and drink alot of beer with some old mates,it don't matter that you broke the motor,you still enjoyed yourself!

Well put Bob :wink: , I might add,,,,,
Teardrop =a small pool of body fluid oozing from the eyes after discovering a failed bigend bearing halts my plans for the meet

Just One?

[David Leikvold]

Hey Rob, if you've decided to go with a bigger tank the little one could always be put to good use as the top piece that forms the canopy and the engine cover. At least you'd be assured that you weren't deviating too far from 0.04. Any thoughts about engines for a bigger tank? A series of bike motors would put your name all over the record book and leave plenty of room for you too.

[Rob]

Doc,

I'm guessing that the Tamai book was looking at "low speed" aerodynamics?
"The Aerodynamics of Road Vehicles" was another text I'd tried to locate in a library here (unsuccessfully).

G'day David,

Logical progression there, tank first, donk second. The bigger the tank, the larger block will fit, the more $$ I'll have to stuff in it and so it goes. One decision I have almost settled upon is 4 wheels.

I'm in no rush and will happily learn from the mistakes of others. I'm a proponent of the age old formula- Time=Money or more correctly, the less time you have, the more it'll cost.

Cheers,
Rob

[Dr Goggles]

Doc,
I'm guessing that the Tamai book was looking at "low speed" aerodynamics?
"The Aerodynamics of Road Vehicles" was another text I'd tried to locate in a library here (unsuccessfully).

G'day David,
Logical progression there, tank first, donk second. The bigger the tank, the larger block will fit, the more $$ I'll have to stuff in it and so it goes. One decision I have almost settled upon is 4 wheels.

I'm in no rush and will happily learn from the mistakes of others. I'm a proponent of the age old formula- Time=Money or more correctly, the less time you have, the more it'll cost.
Cheers,
Rob

I did this rave a few years back on Dave's thread but I think it's worth repeating....When you start a build of something like a tank or a liner have a part of you shed where you can write stuff on the wall. Why? , because you will spend a ridiculous amount of time staring at it, and you will have ideas . Some of them will sound crazy, some will be , some won't. Often they will be at the cold and fizzy end of the day when you're feelin a little light headed...and you'll forget them. Then for some reason you won't be able to work on it for a while( baby, sick, broke, lazy,holiday, moving house) and you will lose the continuity of the ongoing design and fettling.....Likewise it pays to keep some sort of diary, the online one is best because you get input from experts and lateral thinkers both of which are invaluable.....Remember also that pretty much everything has at least been thought of before ......even if it hasn't been tried, you look a bit like a dickhead standing beside something with some bloke explaining to you that you've employed a long since discredited technique or idea just because you didn't look far enough into the past.........sure there ain't necessarily "right" ways of doing things but there are "better".......

Go for bike motors, I can't say it too many times.They rev, they're cheap, they're reliable.......


BTW: I always say to people DO NOT OPERATE HEAVY MACHINERY AFTER READING GORO TAMAI'S BOOK....

[David Leikvold]

I do my best lateral thinking when I should be asleep. Rob, when you get sick of looking for a big tank why not just use the dimensions in that RMIT text book to plot a perfect streamline tank and then get some big sheets of chipboard (Customwood) and make lots of circles in the right sizes. Then attach long thin strips of nice bendy pine to the circles and you almost have a plug for a fibreglass mould of any size tank you'd like. Even better, just do semi-circles and make two of them, or make the bottom one then attach another piece to the plug for the canopy area to make the top half. Or something like that, you get the idea. I like your time is money idea, does it mean that if I wait a few more years that the Celica will suddenly become affordable?

[internetscooter]

Likewise it pays to keep some sort of diary, the online one is best because you get input from experts and lateral thinkers both of which are invaluable.....

If you guys (meaning the DLRA) want a project wiki site like Vespa Labs, I can whip one up on my server. I just need to up my internet connection to make it faster to use.

Here's my new lab project page

http://www.vespalabs.org/User:Internetscooter/Scooters/Vespa_Streamliner

PS: Cd = Coefficient of drag = a dimensionless quantity determining how likely someone is to choose Mardi Gra as an event for early March over Speed Week.

[Rob]

I do my best lateral thinking when I should be asleep. Rob, when you get sick of looking for a big tank why not just use the dimensions in that RMIT text book to plot a perfect streamline tank and then get some big sheets of chipboard (Customwood) and make lots of circles in the right sizes. Then attach long thin strips of nice bendy pine to the circles and you almost have a plug for a fibreglass mould of any size tank you'd like. Even better, just do semi-circles and make two of them, or make the bottom one then attach another piece to the plug for the canopy area to make the top half. Or something like that, you get the idea. I like your time is money idea, does it mean that if I wait a few more years that the Celica will suddenly become affordable?

I got lucky, I sem to have been born with the lateral thinking gene well embedded.
I can get sick of lookin at tanks? I actually have a solid lead on a P-38 (shhhh, don't tell anyone ok) but have zero time to follow it up for now. As for a plug, I also have access to a CNC machine capable of routing, cutting etc etc so a plug would be pretty simple for me to come up with, complete with an accurate cutout so all sections could be slide long a square "spine". Fill the gaps with foam then sand it fair and finish. If I spend that amount of time though it's more likely to be a streamliner than a lakester.

The time=money idea definitely means almost any project will be cheaper provided you have a plan and adhere to it. Many of the parts you need will turn up relatively cheaply over time and even cheaper right after you've bought what you need

I'm in no rush and probably have close to enough to build a car now short of the required safety equipment. Anything that goes "out of date" would be bought as late as possible. There'll be a few more meals at the canteen yet before I consider breaking out the string line and tig!

Cheers,
Rob

[Rob]

Paul,

Have you seen the #500 I/S entry at Bonneville? It's more of a bullet shape (with a cone at the rear) than my tank but if they get inside of there, there's hope for me yet!

I like your streamlined Vespa drawing, I have a few photos saved of similar shapes over time if you'd like them. Not teardrops but still sort of on topic.

Cheers,
Rob

[Rob]

See, you guys have me thinking again dammit.

I was pondering the question, if a teardrop is the perfect aerodynamic shape, why are drop tanks not shaped this way?

I can see girth being restrained for a belly tank where ground clearance may be an issue but thought I'd chuck the question out there and see what came back.

Cheers,
Rob (who's REALLY off this time!!)

[internetscooter]

If you check out the javafoil shapes you'll see that there are all sorts of "perfect" teardrops - some even the shape of a diamond (4 flat surfaces). If you run the calcs you see they perform differently depending on how big and how fast.

I've picked the Van de Vooren shape as it looks close to the original 1951 Vespa lines and performs the best (Cd 0.019).

http://www.mh-aerotools.de/airfoils/jf_applet.htm

BTW - I too plan to CNC up the final design, that's the first thing to build... a CNC machine