got some questions for you horn guys

As you may or may not know i am a part of the audio engineering society at michigan tech. we are a bunch of people that get together to talk about audio. we have university funds, and we are starting projects again for this year in home audio, car audio, and pro audio.

Every winter at michigan tech, there is "winter carnival" is every year in february. all the different orginizations build 'overnight' statues (out of snow) and the best ones win. well last year we built a set of speaker boxes out of ice and snow for the over night show and put working drivers in them. they actually sounded very good and everyone was impressed!! after the huge success we decided we wanted to go crazy this year.

A member of the group proposed that we do a "month long" project.

it would consist of making one HUGE horn out of snow and ice. we would use a large (15") bass driver for it. the only thing is we cannot find anyting on how to do something so big. it has never been done in such a large scale (we wnat the mouth to be 10x10, and the horn about 20-25' long.)

we dont have the expertise to design such a thing because we cannot find adequate information.

i (we) were hoping someone here could give us some insight and some ideas/tips on how this whole thing should/could work. we want this to be as LOUD as possible (bass) and it not to be a big flop.

how do we go about designing the horn? what shape should we make? what type of driver/enclosure? can we just put the speaker right up to the horn? or wont that work. again, we havent found any documentation on large scale bass horns. and lastly, do you think this could be very loud with 1 15" driver? should we go larger? smaller?

Thanks In advance