gaucho

My Feedback: (35)

i have a fuselage from a jhh a4 skyhawk. i want to make a hull to mount it on. i was thinking maybe a tunnel hull design. it will be over 5 ft long. i have a ramtec fan, an OS 65 df engine header pipe, tuned pipe. the lower unit will be made out of foam and glassed with epoxy and fiberglas cloth.if somebody would send me some pictures of some hulls i could use, it would greatly help. thanks gaucho

Mr Cajun Gator

I do not have any experiance with the ductfan units, but will give my 2 cents worth anyhow. The tunnel hull sounds like a good idea, and also the way you are planning to build. The only thing I would change is the length, I would think a little shorter. The topic of this style of hull has been on the post before, but no one that I know has tried it. I have even thought hard about building one.
You could post your question at rc airboat world, about input on the build.

pro27

There were plans for one published back in 1984 ??? in an issue of Flying Models magazine by Bob Aberle. At the time, I think it was an AX40 fan (very early in the DF scene). He had some positive results.

With today's available power output and DF design, the improvement should be great for an airboat.

I would suggest trying to track down the article and starting from there. If you go through some of the older threads here, you should be able to find what issue it was published in, as I have posted it before, but my memory is drawing a blank at the moment.......

Fluid

I remember the article very well - when I contacted Bob at the time he said that the speed was low compared to a tractor prop. He thought it was because of the rather large board he used for the hull, but the thrust of D/F setups has increased substantially in the past twenty years, so today it might work better. He included plans with his article with two top profiles; one was the traditional rectangular shape, while the other used a much narrower back 2/3 of the boat. It ended up looking sorta like a "T" from the top - the idea was to reduce the wetted area. It was in the January 1979 issue, and the plans are still available here:

http://www.carstens-publications.com..._directory.php

I dropped the idea of a D/F airboat at that time and concentrated on tractor props. But his ideas about reducing the hull's wetted area have stuck with me ever since.

gaucho

My Feedback: (35)

thank you very much for the info. will send for the plans and will keep you posted gaucho