|Dec 17, 2010, 01:59 PM|
Operation X-Craft: A Full Size Electric Hovercraft (Mar 19th Update)
The title pretty much sums it up. What I want to do is build a full size hovercraft.
The objective is to build a hovercraft with the following requirements:
- must be able to carry me
- compact size with good looks
- easily controlled
- water and flotation capable
It starts off here: http://www.rcgroups.com/forums/showthread.php?t=1351087
I will need some help though. I have no income. I don't work. I'm only a 17 year old senior in high school. I will hopefully be able to cover the project with my summer money. I went to my school principal for help, my class will help me, and will ask for a little help from family. I will have my list of expenses below in a moment. I have an estimated cost of $1,100.
Must be able to carry me:
The thing about this is that I only weigh 125lbs. I would like to be able to carry 175lbs. Am I being unrealistic? (Don't answer that question, because wether you say yes or no, I will reach the 175lb mark and I will strive for 200lbs.)
Compact size with good looks:
This has to be relatively small for the reasons of cost and portability. Size is money, and everyone knows that that is true. I also don't want to have a special trailer. I would like to just turn it on its side (or just slant it), take the fan shroud off, and throw it in the back of a pickup truck. Of course the rear ened would be hanging off, but ropes and padding can handle that just fine.
I don't like sloppy work. I have done basic school projects till my hand bled from the amount of time I was putting pressure on my hand. I have replaced a partner's efforts with my work if it didn't meet my standards. I have even ticked off (in a good way) my friends when washing cars due to the time I spend just cleaning the rims alone.
I figured size would play a key role in maneuverability. To add to the small size, this craft will be extremely lightweight. It will have an all foam construction with a few ply reinforcements. I aslo hope than my fan selection will give me decent thrust.
If it wasn't electric, I wouldn't be posting this at all. This will look really good for college. I am 17 years old in twelfth grade and am getting my college stuff together. I would like to get in done in time for the science fair, which I think is at the end of March.
Water and flotation capable:
I would like to take advantage of the bag skirt by having the capability to go on water. Things do go wrong though. In the event of a mishap, the foam construction and displacement of the hull should keep the hovercraft, the driver, and the driver's family up out of the water. That family part is just an expression, but you get what I mean.
|Dec 17, 2010, 02:06 PM|
The Hovercraft itself and List of Bills:
- the hovercraft hull
- the skirt material
- the electronics
- various hardware, such as nuts and bolts
The Hovercraft Hull:
The hull for the hovercraft will be made of foam. The foam of choice is what we all know as wallboard. It is the white isolating foam sheets that you find in hardware stores. The hull will be made of 1", 2", and 4" (if I can find) foam sheets. The base will be made of two sheets of 2" foam. Between them will be 4" spacers. These spacers will be responsible for creating and maintaining the strength of the hull. These spacers will also create the air chamber (lack of proper term). If you do not understand my description, you will see what I mean when I post the pictures. The style will come from the fairings. The fairings are not necessary for making the hovercraft work, so its strength doesn't have to be all that. They will be made of 1" foam. The fan shroud will also be made of 1" foam, but will have a 1" thick ring around the leading edge. The control vanes will be made of reinforced 1" foam.
1"x4'x8' Foam Sheet - Cost Each $12.57, Final Cost $?
2"x4'x8' Foam Sheet - Cost Each $21.97, Final Cost $65.91
The Skirt Material:
The common skirt material for hovercrafts is nylon. I want to use polyester, which is more resistant to damage. The skirt will be sealed all around. The skirt will rap around the air chamber. There will be no holes in the skirt.
I will need 8.52 yards.
$9.99 per yard, Final Cost $89.91
I spent a few days looking over a very big list of components. I have settled on the batteries, motors, speed controllers, monitoring equipment, and more. My list is below.
ZIPPY Flightmax 5800mah 6S1P 30C - Six of these will be paired in parallel and series to result in a 17400mah 12S 30C lipo.
Cost Each $68.58, Final Cost $137.16
Turnigy 80-100-A 180kv Brushless Outrunner
Cost Each $99.95, Final Cost $199.90
Turnigy Sentilon100A HV 5-12S BESC (Ver4) - Two of these will be the driving forces behind the motors.
Cost Each $82.07, Final Cost $164.14
Control and Monitoring Components
Turnigy Servo Driver - One of these will control each ESC. I might use another as I am thinking about implementing a complete drive-by-wire setup.
Cost Each $8.95, Final Cost $17.90, Drive-by-Wire Cost $26.85
Turnigy S8166M Servo 154g / 33kg / .21sec - This would be the servo of choice for the drive-by-wire- setup.
Cost each $24.95, If I use two $49.90
Turnigy 6S Mini Lipo Battery Monitor
Cost Each $8.89, Final Cost $17.78
Turnigy Watt Meter and Power Analyzer
Cost Each $23.95, Final Cost $47.90
Turnigy BESC Programming Card
|Dec 17, 2010, 02:07 PM|
So I need some advice on a few things.
- rudder pivots and control horns
Is it better to have longer power leads, longer servo leads, or longer motor leads? My intentions were to have the ESCs close to the motor, and just run long power and servo/signal leads.
Would the servo of choice have adequate torque, while allowing great steering? Specs say it does, but this is specs from hobbyking. 20 grams of thrust is definitely not 32 grams of thrust. (That is of another product.)
Rudder Pivots and Control Horns SOLVED
What should I use for pivots and control horns?
I'll be using custom milled balsa/birch wood with delrin pivot rods.
|Dec 17, 2010, 02:08 PM|
This post will be for the craft's construction. I will update this post by what I have, and not what I am getting. That way, only pure progresse will be in this post.
Hull and Fairings
2"x4'x8' Wallboard Sheets x3
-1 for upper surface
-1 for lower surface
-1 for inner structure
9 yards (61" wide) of 18oz 1000x1300 Denier Polyester
-Greater tear resistance than nylon based fabric
-UV resistant, holds color longer
HH-66 Vinyl Cement
-Outstanding resistance to temperature and weather extremes, oil, fuel, chemicals, and grease
-Remains flexible when dry
1/17- Started marking out lines on the foam to be cut
1/20- Outer edges and inner structures cut
1/21- Hull mockup
1/23- Instrument panel mockup, Rough lift fan hole cut
1/26- Made the four corner and two side spacers
2/2- Not pleased with spacers so I started over
2/5- Glued the lower outer corners, sides, and center supports
2/6- Glued the upper surface, the hull is just about complete
2/17- Purchased three 1"x4'x8' foam sheets, 3/16"x2'x4' ply sheet, two 11x14 plexi sheets
2/18- Began drawing upper deck panel shapes onto 1" foam
2/19- Rounded edges for perfect fite between birch parts
2/20- Glued birch parts together
2/21- Expanded the hinge holes to accommodate delrin rod
2/26- Began soldering
2/27- Cut lower pivot rods
3/6- Working on motor to esc, esc to watt meter, watt meter to split battery leads
3/8- Motor connections complete
3/10- All other parts (except duct) have been cut
3/11- Balance leads completed
3/16- Painting begins, hull, rudders
3/19- All but the side panels are painted
|Dec 19, 2010, 06:53 AM|
It's wise to keep leads between batteries and ESC as short as possible. The leads between ESC and motor can be longer, but best to keep them as short as you can, too. Long signal leads to the ESC's is fine, just use twisted cable.
Why do you need a servo for steering? Aren't you planning to be sat in or on it?
Sorry, can't help much with the rest!
|Dec 19, 2010, 09:37 AM|
- you could control it with a wheel (servo driver)
- you could control it from a distance (receiver). I wouldn't trust handing all the controls over to someone else. There are acceptions though.
- you could sit on it and control it with your transmitter. Some people are better at video games than they are at driving a car.
- the overall servo setup would be lighter. Weight is my main concern.
|Dec 19, 2010, 11:43 AM|
USA, SC, Easley
Joined Sep 2009
What kind of power do think you will need. Propulsion should be easy but the important thing is what kind of terrain are you planning to transverse. If you are planning to travel on say a gym floor it will take very little power to hover. If you planning to travel across grass you will need many times that amount of power. You can hover huge weights with a very small air supply as long as you have minimal loses around the skirt. Also I hope you are successful but you will be taxed to come in at that budget. Must of us flying a 30 pound airplane have 1500 to 2000 just in the motor, esc, and batteries. If you can figure out the power requirements you can figure out the cheapest set up. Even at say 50 watts per pound, and I have know idea about hovercraft power requirements, you will need 10,000 watts. You will most likely need two motor's, two esc's, for hover and 1 set up for propulsion. Even at Hobby king prices you are looking at around 750 just for the esc's and motor's shipped. Now if you need a constant 10,000 watts to hover than you will need a ton of batteries to keep you up, around 235 amps, maybe.
Remember the 1.5 rule. If you budget 1100, I promise it will cost at least 1650.00 or more. However most of the projects I have enjoyed the most have started with someone telling me I couldn't.
|Dec 19, 2010, 12:30 PM|
Power and Weights
I have plans for the power if things don't workout as planned. The 180kv motor puts out 7000W. That is equivalent to 9.387hp. But lets consider that as being optimistic and drop the hp down to 7. The remaining 2.387hp will be safety. Going off of that, There should be enough power to easily get the craft 6" off of the ground.
A UH-10F is around the same size, but has an 8" hover height and weighs 140-170lbs. Specs say a 8-15hp engine that weighs less than 65lbs. You also need fuel.
- The little motor I'm looking at only weighs 1570g which is 3.461lbs. Two of those make 7lbs.
-The batteries taken into consideration weigh 838 grams which is 1.847lbs. Two of those make 4lbs.
- The ESCs only weight 125g which is .276lbs. Two of those make .6lbs.
Note that I added to the weights when I made my estimate. This should accomidate for associated wiring.
So the entire motor and energy package only weighs 11.6lbs. Wow, that is an entire 50lbs less already! Total amp draw will be about 150-190amps, maybe even less.
|Dec 20, 2010, 06:33 PM|
I Smell a prank here.
Check out this "Personal Jet Pack" thread started by "Wise Guy". The owner of the thread deleted some of the pics, one suspicously similar to a few posted on this thread of a hand holding a turnigy motor.
The jet pack kid, I shall call him, claimed to be older than he was... and from what I could make out in a few of the photos's, was in the process of applying to a military academy. That makes this person the same age, interested in the same kinds of things, and well... it doesnt take a PI to draw a line between the dots folks.
Dont get sucked into another one of this guys fake blundering posts.
|Dec 20, 2010, 06:56 PM|
What? Are you...
That is pure crap that you accuse me of being a fake. Have you looked into my posting history or my trader rating or my friend list. You think I have time to waste. It took me hours alone just to put up those first two post. Did you look at the other two threads on this topic that I either started or am part of? There is one in this flippin forum. I want to say some stuff, but I won't.
And who the heck are you to tell me anything? I would say welcome to RCG, but I don't befriend people who lack respect for others.
At least wise guy had an imagination. And last time I checked, that thread has lots of helpful numbers. Thanks for posting it.
|Dec 20, 2010, 07:07 PM|
Whoa! Hang on! If you offend my good friend Kevon, you offend me! I assure you, boredom.is.me is the real deal. He is one of the best guys I know on this forum. If you want proof, just look at his posting history. From micro boats to nano edf research and design, boredom.is.me is a significant contributor to this forum. No fakes here! I think you better take back what you have accused or I will have no choice but to report your abusive post.
Here are just a few of his accomplishments.
He did a massive amount of research for this sticky. http://www.rcgroups.com/forums/showthread.php?t=1172332
He was the key roll in founding this entire forum. http://www.rcgroups.com/micro-and-sub-micro-boats-696/
Suggestion thread here. http://www.rcgroups.com/forums/showt...4#post15221221
From this page to current, you will see his ndf22 designing and work with shapeways. http://www.rcgroups.com/forums/showt...963732&page=18
Here on shapeways you can find some outboard boat motor stuff that he designed. http://www.shapeways.com/shops/microboat
|Dec 21, 2010, 01:23 PM|
A few things.
First, I simply put my observations down and made no direct accusations. Feel free to report me for abuse if you wish but I'm afraid that there is a drastic lack of evidence for that claim.
Next. Yes, I can see that this gentleman has a significant post history. And, in his defense the Mr "Wise Guy", and owner of another thread mentioned near the end of that thread about a newb getting a rather advanced EDF jet for a first "RC project " both had rather new accounts and few posts. For this reason I will concede that there may be more credibility to this thread than the others. However, I see too many similarities between the posts to buy into this myself. That is why I posted what I did. People on this forum should be able to make decisions themselves, and if they wish to follow this thread than more power to them.
Oh, feel free to say whatever you wish, you wont hurt my feelings. I have nothing to apologize for, and if you were offended by my observations, than that is your problem to deal with, not mine. I will not "Haunt" your thread, in fact this will be the last time I post on this particular thread. I'm sure several scathing replies from numerous people will follow, but I could really care less. As you can tell by my posts and trader rating, I have not been around here too long, and have no real vested interest in anything here. Another thing i'm sure will come up in the aforementioned scathing posts.
If this is real then best of luck.
|Dec 21, 2010, 05:27 PM|
I see your point. A word of advice though. Just keep your observations to yourself. I just feel like your post made boredom.is.me seem like he might be less than he really is. I stand up for him because he deserves so much more for his incredible work. I too am only 17, and although I've had my own success, I can only hope on day to have the motivation and talent that boredom.is.me has. Yes, this is a prestigious project. Yes, most 17 year olds would not hold through to the end. Yes, I think Kevon is capable of finishing this project. And yes, I am confident he will.
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