NFB-- Some ideas for physics project...

[immgeorge]

Alright, for AP Physics, we have been instructed to construct a boat... It must take 2 people to the other side of the pond (where a flag is obtained) and back while gathering objects from the water... Being an overly ambitious idealist in a group of similar people, we have undertaken a complex design... We have 2 10 ft long pipes that are 15" wide... We calculated it to hold 700 lbs... and then some...

Anywho, I've been trying to figure out how to break the water in front of the pontoons (the 2 10ft sections of pipe) to help with the fluid dynamics (i think that's the term used here...) The pipes have plastic caps on them...

The best idea we have so far is to cut the pipes into a point on the forward end and figure out how to seal it... That seems like a pain... Well, I've been racking my brain all day... And you guys seem to be a ingenious bunch and was wondering if yall had any ideas that would... simplify... the resolution???

You guys are the greatest...

[JasonG]

hmmmm I'm sure any parts or hardware store should have some type or ornamental objects that you could somehow fasten to the front of the pipes to help streamline it. Something like a cone shape that you could epoxy to the front. Or if you good with your hands grab yourself up some wood and see what you could come up with. Good luck at any rate.

JasonG

[immgeorge]

thanks, I went to Lowes earlier, but it gave me another idea... I'm goin to Wally world to see if they have any deep salad bowls around 15 inches wide...

this thing is gonna be a beast if it ever gets put together... we still have to work out the pedal system... and the paddle... and the rudders... I'm gonna post some pics just to show it off once its built... unless it sinks to the bottom of the pond...

[Jeff_in_Atl]

Figure out what the resistance is of a 15 inch diameter pipe what 2/3 submurged is in drag of a flat nose vs a a taperd nose and see if it is worth fooling with. I guess my point is you're not going to be going but like 2 mphs with paddles. Yea if you're building a speed boat, I could see it.

Now as for your question, he he he, this is like junk yard wars, how about a wire mesh screen which I know Home Depot has and put fiberglass on it. You can form it however you like.

How about a stainless kitchen mixing bowl. a dome is better than flat.

We have a ME co-op from GT where I work. I'll have to send him this thread tomorrow.

[immgeorge]

We know we won't be the fastest, but our pedal-er is a competitive bike racer... he's strong as an ox, we're hopin he can get us up to a good cruisin speed so that we can be like the truckers or something haulin down the highway.. our boat is about 10ft by 6 ft... the only other boat from our class that I've seen fits in the hatch of a late 80's stang... Can you say king of the pond...


Oh yeah, I'm gonna try to get the races video taped... Should be worth a laugh or two...

[Jeff_in_Atl]

LOL This is great. But i have to ask, are you sure the 15" tubes will be large enough? Don't forget about the weight of the tubes and the gear you are going to mount on this thing. It doesn't sound like you will have much margin.

Post a picture of your sketch.

[immgeorge]

Well, this is kinda sketchy, but I think I got the math right...

each tube's inner volume is 7.5^2*3.14*120= 21205.75in^3...

21205.75/1728=12.27ft^3...

weight of water-- 62.43 lbs/ft^3 (got figure from some site)

62.43*12.27= 766lbs of bouyancy per float...

the pipe is 4.7lbs/ft -->mfg.'s figures...

10*4.7=47 lbs per pipe.... 766-47= 719 lbs net per float... so thats 1438lbs total... now, if the frame is 100lbs & we load up 600 lbs of people and pedal equip, it should sit about half way down the pipes, right??? Does anyone see any problems with my math???

[immgeorge]

I don't have a sketch, but I took this last night after we had everything cut and fitted... its just kinda lying there, nothing final... just an idea of what it looks like... and my camaro can kinda put its size into proportion...

[Jeff_in_Atl]

I have no idea about the math.
What is that covering the end of the pipe?
What are you planning for "pedel equipment" and getting the power to the water (prop or paddle wheel)? LOL

[Jeff_in_Atl]

Now what kind of seats are you using?

[RangerBob]

Your riibbed tubes will slow you down (not for boating pleasure).


What is you money limit for the project?

Bob::

[immgeorge]

The pipes are now capped off with caps that are made specifically for these pipes... They are normally used for sewer stuff and are airtight...

We have a paddle wheel, its 2 bike rims with sheets of metal between them, we plan to test out the depth of the paddle for best efficiency...

We have a chopped up bike frame with the crank and everything for the pedals and we are gonna figure out a way to mount that right above the paddle and have the chain go down to the paddle, which is fixed to a floating axle...

The person pedalling will be seated (haven't gotten that far yet), the other will be gathering the objects strewn throughout the water...

We are going to cover the pipes with plastic sheeting and seal it as best as possible to negate the ribbed sides... Even if water leaks into the plastic, it should still be better than just bare ribbed sides...

As far as money goes, there isn't a real limit. The teacher doesn't want us to spend too much though... We are contacting the pipe manufacturer and have told them what we are doing, and hopefully they will donate the piece of pipe (est. cost- $80).. My dad works at a piping supply co, so he has all this stuff in his warehouse... and as far as the pedal goes, another member of the group works at a bikeshop, so its just spare parts... Overall, we haven't spent that much....

Oh, and Jeff, nice concept diagram... I'm using that in our logbook to track our progress!

[immgeorge]

Well, today was the day we tested everything. The pipe exceeded our expectations. We had it loaded with over 600 lbs of people and the pipes were only 2 or 3 inches into the water.

We ended up playin around in the lake for a couple hours on it. It doesn't have a drive system yet, so we had to use paddles. Its alot easier to get it to move than I imagined. We won't be winning any speed contests, but we figured we could float even more weight than our estimated 1400lbs (because of the ridges)...

We've got some pictures, I'll see if I can get them up sometime...

[immgeorge]

Today, I was able to breathe a deep breath of relief. Our pedal system driving a paddle wheel is now complete. The best part of it is... the thing moves! We're talkin 2 10 ft sections of 15" corrugated pipe with no sort of external modification, topped with a PVC frame and plywood flooring... We were able to travel approx 50 feet in 10 seconds... based upon our original design and expectations, we could not ask for better results... I'll get some pics tomorrow after we make it better looking. And the race video will come some time next week