EDF Jet Boat

[Lewist]

I had a thread a little while back about an EDF swamp/jet boat using a single speed 400 powered EDF.

I have now got the time and the resources to remake it as a twin.

the specs are as follows:-

2x SF TurboFans (70 mm fan)
2x Graupner Speed 400 6v Motors
12x GP2000 cells (14.4v)
1x Ripmax Xtra 40amp ESC
1x Futaba micro RX
1x Supertec Pico BB servo (steering)
1x Supertec Pico BB servo (trim tabs)
1x Hitec HS85 servo (airbreak)

I had a problem with my single version. It would porpouse a lot and i think it was due to the short lenght compared to width. It was almost square. I am going with the same sort of proportions on this boat but I am going to add some large trim tabs at the rear controlled of a 3rd chanel so i can adjust the trim of the boat in-flight! I may also ad a large wing above the engines to help give it some stability!

here are a few pictures of the cad work i have done for this boat so far.

[Kmot]

Way cool! :)

[tsenecal]

this may sound odd, but perhaps an adjustable wing at the front of the boat may help as well as the trim tabs...

[pitviper51]

swweet, look forward to seeing this thing in action, also agree with some sort of trim wings to help fly in around on the water, or to keep in on the water haha,
mike

[Lewist]

Yeah, as mentioned in my first post i am going to put some trim tabs on the back and hook them to the 3rd channel on my TX so i can adjust the trim of the boat as it goes along and i hope that alone will be enough. If not I will try out various different wings and things to see what difference i can get.

I could just make the boat longer, but i like the short dumpy look, and the single version turned so well, at full speed (25+MPH) it could turn in a diameter of about 40 feet.(this is with no turn fins or anything like that in the water!) I just needed to reduce the bouncing. It would sometimes get really bad under hard cornering and the boat would spin out! but it did make it interesting!

The first version of this was quick, and i have learned alot from that, its going to have more than twice the thrust of the origional but its not going to weight twice as much! I am also going to add an airbreak to it because the first one i made would run on for a long time off power, and ofcourse wouldn't turn. So i am going to fit a large airbreak on the boat that will pop up from the deck.

[Lewist]

OK, well i have basically finished the cad work, a few of the parts on this boat arn't modelled because its just easier to free form them over the bulkheads.

I have started to cut out some of the bulkheads and will do a little more cutting and sanding tonight and post some pictures tommorrow.

[pitviper51]

cant wait to see it,
mike

[keven64]

You need upthrust to stop the porpoising Lewis... :D

If you cannot arrange for that by physically moving the fan units so that the intakes are closer to the waterline than the exhausts, you will have to add vanes to deflect the air up.
Whilst you are at it, the best trim vanes would also be behind the fan units - so that their effect is directly proportional to the speed of the boat ! :cool:

Where are the photographs ? ;)

Keven. :)

[Lewist]

Keven - thanks for the info....

the photos are on thier way. Not had much chance to do any work on it over the last two nights, but tonight i will finish cutting the main hull piece and all the bulkheads and frames and start sticking it all together...

then time to have fun with the NASTY polyester finishing resin and fibre glass.. i hate that stuff!

[green-boat]

I have better luck using epoxy resin in place of polyester resin and it doesn't smell as bad.

[keven64]

I posted this in Electric Ducted Fan Jet Talk...
Lewis,

I've been looking about for fan-powered airboats, and can find only one to date - but it is rather inspirational ! ;)

http://www.rc-airboats.com/gallery/view_album.php?set_albumName=EDF-MantaTake a look at what looks to be a Scorpio Manta Ray with the wings chopped...!

My airboats are far simpler - and have many more corners !

Keven. :)

[Lewist]

right just to let you know i have made progress. the hull is taking shape nicely and i will post some pictures of my progress tonight.

[freshoranges24]

which cad program are you using, i want to design my own boats, but i can't find the right software?

[Lewist]

I am using AutoCad 2004

it works pritty well, i think there are some better programs out there to do this sort of stuff with, but it works for me!

[Lewist]

Haha

Just came across this whilst doing some hunting.

Never managed to finish this project, stuff got in the way.


I am, however, in the process of making another single airboat, except........ my pet cockatiel decided to eat part of it! He seams to like balsa :(

Will upload some pics and drawings etc.

Lewis