EPP Scratchbuild - White Viper

[bigbadbob2003]

Hey all,

I have just finished my first scratchbuilt hovercraft from epp using 2 10gram brushless motors.

I started out with skirtless in mind but decided to have a go at a skirt and i am glad i did, it hovers at a much lower rpm now.

http://www.youtube.com/watch?v=xOE4JMTbVbU

I have sorted the skirt out now so it doesn't lean to the right like on the vid.

Plans are for personal non-commercial use only.

[metroidrc]

not sure how i missed it... Very cool! an EPP hovercraft would be very lightweight so the performance should be pretty good.
Nicejob!
-Josh

[bigbadbob2003]

Thanks Josh

It is extremely light weight, i am using 300mah 3cell lipo. At a guess i would say about 125grams altogether.

I am going to take it to the sports hall where we have our indoor flying so i will get chance to open up the throttle. I am barely even using the throttle in the video so the potential speed could be ridiculous. I think i will have to watch out for it flipping with it being so light tho.

Rob

[metroidrc]

yep i'm not sure where you have the battery but probably move it up close to the front to keep it down at high speeds - or a spoiler :)

[metroidrc]

bob you should upload your video to rcgroups videos too, I think people would enjoy it in the other categories as well.

[kd7ost]

That looks very sharp.

I did a quick search on EPP foam and find miles of hits but can't seem to find where you guys buy that stuff. Is it something that you can get at the hardware store?

Dan


edited to include
Actually I just modified my search to include the word "source" and it looks like it is purchased on line. Evidently not a real common foam.

Dan

[metroidrc]

I buy Epp foam for my airplanes at www.rcfoam.com

[kd7ost]

I buy Epp foam for my airplanes at www.rcfoam.com


Thank you for that link metroidrc.

Dan

[bigbadbob2003]

i got mine from http://www.epp-versand.de/ with me being in the UK

[daoldguy]

Very nice Bob, and when it is made from EPP, it is safe for me! :eek:

Cheers
Ron

[bigbadbob2003]

Heres where i place the battery hopefully is forward enough. Its placed on top of the carbon cross to stop the epp from flexing.

[bigbadbob2003]

i have placed a zip with high res pictures here http://www.dude-ware.co.uk/Rob/hover.zip which should get most people started on building this craft. No skirt pictures yet will do them when i get chance.

[daoldguy]

i have placed a zip with high res pictures here http://www.dude-ware.co.uk/Rob/hover.zip which should get most people started on building this craft. No skirt pictures yet will do them when i get chance.

These are great pics and pdfs. What are you using for the bag, I know you mentioned it leaned at first but you got t sorted out.

Ron

[bigbadbob2003]

The skirt is made from a plastic bin bag, i cut another base out then laid it on top of the bag and cut the bag so it was about 2" bigger all the way around to get the size, i will have to explain the glueing process when i have some pictures.

[MrFlash]

Wow ..great job Rob !!!.

Cant wait to see this at the indoor !!. Remind me to bring the camcorder and ill try and get some WOT vid !!

[bigbadbob2003]

My dad has built a hovercraft too so there will be a bit of racing going on lol
He decided to design his own craft.

question is what session do we "fly" in lol

[daoldguy]

My dad has built a hovercraft too so there will be a bit of racing going on lol
He decided to design his own craft.

question is what session do we "fly" in lol

All Sessions?

These can be used for the safe retrieval of Mid-Air victums, float right out there and push them off the floor :D

Ron

[MrFlash]

All Sessions?

These can be used for the safe retrieval of Mid-Air victums, float right out there and push them off the floor :D

Ron

:D:D:D

yup Medivac Retreval ;)

Hope K dosnt class it as a heli :p

[bigbadbob2003]

I think its closer to a prop hanging plane than a heli ;) lol

[bigbadbob2003]

Ok, here are some pictures of the skirt.

It should be obvious where i have glued in the centre part of the skirt.

The way the skirt fills up is very simple it just hangs slightly over the edges of the centre circle and catches some of the air as it goes past.

The skirt was glued to another piece of EPP the same shape as the base then the craft was glued on top of that. I did it that way as i wanted to test it without messing up the bottom of my original craft. As a side effect it gives a very clean look around the edge.

[daoldguy]

Ok, here are some pictures of the skirt.


Hey Bob,

That is crystal clear, my main area of confusion was the "inflation" process and you covered it. I hope we can see you and your dads crafts in action soon. <hint VIDEO> :D
Thanks Again
Ron

[bigbadbob2003]

Our next indoor is on the 16th so we should have some video then :D

[MrFlash]

Dont forget to PM me to bring the cam Rob (Ive the memory of a goldfish :D)

[daoldguy]

Dont forget to PM me to bring the cam Rob (Ive the memory of a goldfish :D)

I think the show MythBusters proved the gold fish memory is longer then 7 seconds...... but that was related to food. :D

[bigbadbob2003]

I have just put the Viper on the scales and with a 3s300 it came in at 154grams and with a 3s540 176grams

[bigbadbob2003]

Here is a short video from sunday, Thanks to MrFlash

http://vimeo.com/2270980

[daoldguy]

[QUOTE=bigbadbob2003]Here is a short video from sunday, Thanks to MrFlash

Hey Rob,

That thing gets along very nice! Seems like it is very responsive to control. Soon as I get this Cassutt off the table I have got to have me one of those! Thanks for posting the vid.

Ron

[bigbadbob2003]

While it does work its not quite as responsive in the turns as i would like, to turn the throttle has to be dropped so the craft drops down on the skirt creating more drag for it to pivot on. If you dont it turns like at the end of the video in a very wide arc, which isnt good when someone decides to put a lamp in front of the flight line!!

I'm currently modding it to use thrust vectoring rather than a rudder which should help i think.

One thing it does very well though is clean the floor! my skirt and craft are full of dust and dirt now lol

[metroidrc]

nice vid!!! I wish I had a gym like that for indoor flying and "hovering"
oh I forgot to tell you that epp can collect dust pretty good!

[daoldguy]

I'm currently modding it to use thrust vectoring rather than a rudder which should help i think.

One thing it does very well though is clean the floor! my skirt and craft are full of dust and dirt now lol

Would thrust vectoring require things to be set back toward the read, seems if you didn't, it would push the craft sideways of sorts?

I have seen some rudders set up to hang off the back of the craft with 3 rudder blades. I am interestet to see how it turns out.

Ron

[MrFlash]

It looks much faster in real life....and he won the limbo comp easy :D

[metroidrc]

looked fun. :) my only concern with thrust vectoring is it would not be durable if you flip the thing over - but that would require lots of speed and the thing is pretty light anyway.

[daoldguy]

It looks much faster in real life....and he won the limbo comp easy :D

If he would have lost the limbo contest, sterring would be the only reason. :p

[bigbadbob2003]

I have changed my mind about thrust vectoring, i had it working and it made a huge difference but i think it will just flip the craft over if it actually had some speed going, it also made the craft lean to the side alot when it turned.

I wasnt too keen on having a swinging prop at ankle level either as the prop cover has to be taken off to allow the air to move in the correct direction. So i think i will be going with the 3 rudders idea instead.

I have moved the motor now so i can put a 5" prop on to give a bit more speed.

[daoldguy]

I have changed my mind about thrust vectoring, i had it working and it made a huge difference but i think it will just flip the craft over if it actually had some speed going, it also made the craft lean to the side alot when it turned.

I wasnt too keen on having a swinging prop at ankle level either as the prop cover has to be taken off to allow the air to move in the correct direction. So i think i will be going with the 3 rudders idea instead.

I have moved the motor now so i can put a 5" prop on to give a bit more speed.

I think if the 3 rudders can all but stop the air from producing forward thrust while turning, you will get the spin you need. Did that make sense?

Ron

[bigbadbob2003]

well i did the 3 rudder mod and it only made a slight difference, i then decided to move the battery location so it sat on the rear motor support behind the lift fan which made a huge difference it can now almost spin on the spot, but now i have a new problem.... it takes off! i put a spoiler on the front and that didnt really work. any ideas?

[daoldguy]

well i did the 3 rudder mod and it only made a slight difference, i then decided to move the battery location so it sat on the rear motor support behind the lift fan which made a huge difference it can now almost spin on the spot, but now i have a new problem.... it takes off! i put a spoiler on the front and that didnt really work. any ideas?

Wow...Never thought about a land based vehicle needing a CofG. Since that made such a difference moving the battery, maybe that is the key?

I am almost done with my mini Cassutt, the viper is next on my list. :D

[bigbadbob2003]

Neither did I, the only reason i tried it is because my dads hovercraft design is alot more agile than mine and that is where he has his battery. It seems to determine at which point the craft pivots. maybe i just need elevons and when it takes off i can just fly it :p

[daoldguy]

Neither did I, the only reason i tried it is because my dads hovercraft design is alot more agile than mine and that is where he has his battery. It seems to determine at which point the craft pivots. maybe i just need elevons and when it takes off i can just fly it :p

Well that sounds good and all but I already got too many thinkgs flying round here :cool:

If you look at the "swanp buggy" or "airboats" those things can tun on a dime and all the weight is at the rear. They tend to plane nose up but are very heavy so the no fly rule applies.

Question, does it seem to turn one way better then the other? What if the downward thrust is causing a prop torque? I seen a video the other day of a tiny retail production hover craft, it only had the read facing fan, the bottom 1/3rd of the fan forced air under the back to inflat the bags and create a air cushion verses a thrust based float, any chance this could change things?

Ron

[bigbadbob2003]

Not that i have noticed, there was the tiniest bit of torque spin when i started and i had the lift motor at 25% but the lift motor is turned down now to about 18% on the pitch curve which has pretty much eliminated it. It doesnt take much effort to inflate the bag and hover the craft the motor could probably swapped out for a 5gram brushless but i dont think i need it any lighter lol

I have noticed on the racing hovercrafts the lift fan is at the front of the craft and that is also how my dads is designed rather than in the middle like mine so maybe thats important.

Below are some pics of what my dads craft looks like

[daoldguy]

Not that i have noticed, there was the tiniest bit of torque spin when i started and i had the lift motor at 25% but the lift motor is turned down now to about 18% on the pitch curve which has pretty much eliminated it.
Below are some pics of what my dads craft looks like

Well at 18% it is not even breaking a sweat. Well we can't let Dad be one up on the project :D and I agree that lighter is not the answer. Maybe shorter would turn better <just thinking outloud>.

I am also working on a WIG <Wing in Ground effect> and I get the feeling the same issues may also show up.

Ron

[metroidrc]

Hey Ron,
Let me know how it goes with your WIG. I spent quite awhile on mine before perfecting it. It took about 5 models before I got it to work right. Now it works great but the weather sucks!
Bob your dad's hover looks almost like the Ikarus model! :D
-Josh

[daoldguy]

Hey Ron,
Let me know how it goes with your WIG. I spent quite awhile on mine before perfecting it. It took about 5 models before I got it to work right. Now it works great but the weather sucks!
Bob your dad's hover looks almost like the Ikarus model! :D
-Josh


Hey Josh, which WIG style did you go with. I started out with the Tandeum but have been looking and the other one <starts with and L> that I can't remember the name. I would be very interseted in seeing what you have done.

Ron

[metroidrc]

Ron,
I decided to come up with my own design that is not similar to any of the others out there that I have seen. I cannot show it because I think it would be copied if someone saw what I did. The only clue I can give you is that it looks like my razorback hovercraft as a WIG vehicle.
-Josh

[daoldguy]

Ron,
I decided to come up with my own design that is not similar to any of the others out there that I have seen. I cannot show it because I think it would be copied if someone saw what I did. The only clue I can give you is that it looks like my razorback hovercraft as a WIG vehicle.
-Josh

Interesting, so you intend to market your design?

There are 4 basic designs that have been around since the 40's
Ram
Lippisch
Ekranoplan
Tandum
http://www.se-technology.com/wig/index.php
Click "What is a WIG" and then "Conceptual design". Are you able to say if any of these are in the direction you have taken, without giving up any design info?

I personally want to shoot for the Lippisch, these vehicles have gone into production manufacturing.

Ron

[metroidrc]

Hey Ron,
I'll send you a PM we're getting a little off topic here ;)
Wigs are cool though!
-Josh

[bigbadbob2003]

hey Ron have you started on a viper yet?

[daoldguy]

hey Ron have you started on a viper yet?

Not yet, I just bought to cheap light weight motors for the project, wanted to get all the pieces first. Hows testing going with yours?

Ron

[bigbadbob2003]

Ive not really done anything else on it recently, i got carried away designing and making a mini Edge 540 the same size as the cassutt.

I actually prefered the original design of the viper, guess i gonna have to make another :rolleyes: one thing i do want to try is a different skirt design similar to my dads. i think its called a wall skirt i have drawn a pic to show what i mean.

[daoldguy]

Ive not really done anything else on it recently, i got carried away designing and making a mini Edge 540 the same size as the cassutt.
i think its called a wall skirt i have drawn a pic to show what i mean.

Hey, that Mini edge looks great, with the Cassutt Build style used on other planes, the options are endless. I am ready to maiden my Mini Cassutt, weather has been BLAH. Soooo many things I want to build, it never ends..

That Wall skirt looks cool, I cant say I understand how it works completely but I see the reason.

Ron

[HoverTim]

thats a C skirt ok for land but not too good on water if you stop on water you may not have enough power to get back to hover also the skirt will need to be tild the the machnine to stop it from blowing out so it depens on what surface you intend to run

[bigbadbob2003]

did some more modifications earlier, shortened the length and added a lower deck and the c skirt. having trouble turning left at the moment not sure if its a torque issue or a rudder issue yet. as the rudder supports keep coming loose.

here is some clips i took. it has gained a hell of alot of speed!

http://www.youtube.com/watch?v=g9o1QN74O0U

[Xmodgeek]

Nice shoot at the end :) have you tryed it on a rough surface, like on a side walk or road?

[metroidrc]

its probably a torque issue... If you can add more left rudder that might help a little...

[bigbadbob2003]

i've not tried it on a rough surface yet, the skirt is only made from a trash bag so i doubt it would last very long outside. it was designed as an indoor craft for the gym floor at our indoor fly in.

ive redone the rudder supports now add added abit of left on the rudder so i will test that tomorrow

[daoldguy]

here is some clips i took. it has gained a hell of alot of speed!

HAHA, that thing has got some ZIPPPP too it. :eek: I like it!!!!

Ron