Speed Machine: 74mm Ducted fan hovercraft

[hover dude]

Hello all!!! Here is a build log to for my latest hovercraft. The name of the game here is SPEED!!!! It is rather late here so I will go over more specific details tomorow. But it is going to be a all depron and balsa model powered by a 3 cell 2200 mah lipo. It should be pretty fast. As I said more details and pics are coming , please ask as many questions as you like.

[metroidrc]

wow looking good so far! so I do have some questions for you...
one 70mm fan? are you diverting part of the thrust into hover? if so how much?
and what is it made out of? doh - i read that its balsa and depron. might want to cover it with something, or put some REALLY strong reinforcement in the front if you plan on going over 20 mph with it, most likely first time out you'll bump into something (like a friend I know) and explode the whole thing. well anyway - do lots of testing before you get it up to speed! I'll post mine pretty soon too.
Can't wait for more pics!
Great start! :D
-Josh

[hover dude]

Yea its going to be one fan for both lift and thrust. Right now i am thinking i may divert a little over a third of the thrust for lift. Also as far as strengthening the front i will eventually galss the nose eventually. pics vare coming soon.

[metroidrc]

got any new pics?

[hover dude]

Alright this has been a really bad build thread cause i have been so busy and havnt had time to post pics. well the craft is just about done and i have tested it. I Just tried to post all my build pics but it is not working for some reason. I will try again though.

[hover dude]

Well I tried Firefox and now all seems to be working. Here are the pics. I have only done the initial testing. So far so good. The craft lifts off at the lowest power possible. It is also well balanced. This thing seems like it will be a bullet. I just need to find a good place to test it. If anyone is interested the skirt is made of ripstop nylon for kites. I was initially going to use black trash bags for it, but i had the nylon laying around. It works great. Please feel free to ask questions. Also check out these videos of my last hovercraft.

http://www.youtube.com/watch?v=xlrIrPSbD5A

http://www.youtube.com/watch?v=r2YgMS5sqYs&feature=related

[metroidrc]

NICE!!!!!!!
Wow thats a great update.
So the video is another one? Or is that the same?
Pretty cool! Awesome job!
-Josh

[hover dude]

No that is a hovercraft I made earlier on in the year. Its a lot bigger than the one i am building now and is spinning a 12 inch prop.

[HoverTim]

very nice your craft seems to get the hump speed well stick to rip stop nylon its great for model hovers

[Eric1180]

I made a hover craft with the normal 10 in prop and rudder but the base was just a metal wire basket with a coat of paint on the metal wire it did REALLY well on tile ... laminated floor and concert. Rough concert not bad for 20 min but it was scary sense prop stuck out like 2 inch on each side. very fast never got it up to full speed because no enf room. Easy 20mph for sure.

[hover dude]

Just to clarify the videos I posted were of a hovercraft I built earlier on in the year. Not the ducted fan one i am working on now. Thanks for the comments guys.

[zagimon]

Looks good from what I see. The edf version will have more thrust I bet.

[hover dude]

HEre is a quick video of some initial testing. http://www.youtube.com/watch?v=Sdzc8wi1uGc

[metroidrc]

looking sweet! how big is it? approximately :)
can't wait to see it go...

[hover dude]

It is about 60cm by 25cm. So in inches 24 by 10.

[metroidrc]

that tower pro fan that you have has plenty of power, it should go pretty fast! just make sure to put all the weight in the nose....

[SilverHeli2000]

What exactly would be the purpose of having the elevons on this? Would it help with downforce? I guess I just dont exactly understand the purpose.

[liam2317]

Hey hover dude! Great looking hovercraft you have here. I was wondering if you could post some more info (and maaaaaybe even some plans) for that first hovercraft you built. The newer one does look cooler but I'm on vacation for 3 more weeks and all I have to work with is a prop right now, no EDF.

Thanks a million,
Liam

[2fly2much]

Great work, I mean really great work, your a very neat builder and I just love the skirt. I don't want to be a pain but could you tell me more about how you built the skirt, how it folds in?, what shape did you cut?, how does it get the air in there?. Thanking you in advance. Sorry about all the questions.


From Brett.

[hover dude]

Sorry guys i have been in nigeria for the past 3 weeks and rcgroups blocks all ip addresses from there, thus i have not been able to access the forum.
Liam do you have any experience with hovercrafts at all? If not ask me more specific questions if u want. Well basically that model was a 1 meter by .5 meters in size and about 6 cm high when the skirt is not inflated (inner side wall). It powered by a 600 size hobby city outrunner. That spins a 12 by 6 prop. Basically what i then did is channel about a third of the thrust into the skirt and then from there the left over air was fed into the plenum (air chamber under the craft) by holes on the inside side walls of the skirt. I can send you some pics if you want which will make it much more clear. You should check out model-hovercraft.com . That website is a great resourse and even has a free plan on it. The plan is wat i started out with in 8th grade and i havnt looked back sinse. I will say that the griffon plan on the site is rather underpowered and i would suggest going brushless for better performance. Again though feel free to ask me more specific questions.

Brett thanks for the complements. THe first thing i will tell you is that i am no expert in making skirts and this is actually the best one that i have ever done. FOr most of the the craft i have been making i have just taken a straight peice of plastic and just taped the skirt on all the way around, without doing any planning or adjusting for corners. Then just tape it to the bottom to compete the bag. To be honest this method actually works very well if the craft is rectangular hor has well rounded corners (like my prop model). However for this model sinse it has such a sharp nose that method does not work as well. You wont like my answer to how i made this skirt work out because you will need a peice of software to replicate wat i did. I model the skirt on a cad design sofware called Catia and then used it to "unfold". After this i printed out the sections. Using these sections i cut the pieces out of rip stop nylong aka kite fabric (the best stuff for skirts) and glued the cut sections together. I then glued the skirt to the hovercraft and tape the underside. Again this was the first time i tried somthing quite this sophisticated and it worked well. I am sorry i cant be of too much help, but i f you have Catia i can help you a little more. Again feel free to ask questions.

To all i hope to do some more testing on both the speed machine and my other hovercraft in the next week.

Hoverdude

[metroidrc]

any updates? :)

[hover dude]

Well since i have gotten to college i have been rather busy. hopefully i can get back to it soon.

[hover dude]

I just realized that I never did post any videos of how this craft turned out. To make a long story short it was underpowered. My guess is that using a single ducted fan for lift and thrust does not work too well because they produce so little thrust in the first place compared to props. That being said the craft was not slow and it handled very well (especially over water). The sharp body shape did not seem to want to flip, which was good. It just was not anywhere as fast as i wanted it to be. I've attached a video for you all to watch.

[hover dude]

Here is the video guys Link (http://www.youtube.com/watch?v=XpZHxp6bv8Y)