Author Topic: Swift Flyer  (Read 10910 times)

Offline Lykle

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Swift Flyer
« on: March 20, 2015, 09:12:25 AM »
This is a start of my second vehicle.
After building One


I feel the need to design and build the next one.
It is to be called the Swift Flyer. It will be a tilting three wheeled vehicle.
The seat and the rear wheel will tilt up till 45 degrees while the front wheels tilt a little.

The tilt and steering will be done using feet. The hands will only be used for throttle and brake. Power is by electric hub motor. (for now)

The tilt mechanism uses two foot pedals that control the tilt mechanically. By pushing the right foot forward, the main frame tilts counterclockwise (looking forwards). This also causes the steering to steer a little bit to the left. By pushing my toes on my right foot forward, I increase the steering angle to the left. In my mind it feels like skiing. So I hope I will be carving up the road. Because everything is controlled mechanically, I have direct feedback and my left foot is controlling.

I am still very much in the design phase. Working out the various angles, connections and if I have enough tilt and steering angles. I also designed a scale model that I will print out, when my printer finally arrives.
 
It is going to be a wild ride, not only the design and build phase, but also the ride itself. I hope you like it.
Lykle

Design, Build and Enjoy life.

Offline vtsteam

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Re: Swift Flyer
« Reply #1 on: March 20, 2015, 09:34:01 AM »
I lykle very muchkle  :clap:

Now this ought to be an interesting thread!
I love it when a Plan B comes together!
Steve
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Offline Joe d

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Re: Swift Flyer
« Reply #2 on: March 20, 2015, 10:01:28 AM »
This is intriguing.  Looking forward to following along.

Joe

Online Brass_Machine

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Re: Swift Flyer
« Reply #3 on: March 20, 2015, 10:24:39 AM »
Awesome! I have been day dreaming of designing a trike for years now. I will be following this one closely!

 :beer: :beer: :beer:

Eric
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Online Brass_Machine

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Re: Swift Flyer
« Reply #4 on: March 20, 2015, 10:26:05 AM »
I would like some more information about your first build. Do you have a build log anywhere?

Eric
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We're all mad here. I'm mad. You're mad.

Offline NormanV

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Re: Swift Flyer
« Reply #5 on: March 20, 2015, 11:12:44 AM »
Hi Lykle, that's a really good vehicle, shame you got the steering wheel on the wrong side!
I look forward to seeing your trike develop.
« Last Edit: March 20, 2015, 11:44:03 AM by NormanV »

Offline tom osselton

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Re: Swift Flyer
« Reply #6 on: March 20, 2015, 05:25:33 PM »
Interesting design but I'm thinking about the front wheels being so close together and am wondering about it rolling when the center of gravity is changed. I have a quad that I rolled 2 years ago I stopped on a hillside and was suprised how fast it rolled (750 lbs) luckly I had the 2 seater version  with pasenger backrest and only recieved 2 cracked ribs!

Offline Lykle

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Re: Swift Flyer
« Reply #7 on: March 21, 2015, 02:43:16 AM »
Hi Guys,
Thanks for the encouragement.
There is no build log of One, it just happened. Took me 7 years to design and build.
The difficulty was to make sure that it was road legal. That took some doing as the Dutch rulemakers do not like you building your own car. But I managed to do it. I sold the car before moving to Cyprus. Because yes Norman, here the steering wheel would have been on the wrong side. 

Anyway, Swift Flyer. It will be a long process as money is tight and I am doing this carefully.
Because the whole bike tilts and the centre of gravity is so low, I don't think tipping over will be a big issue. I will post a side view soon. The idea is that I will not need to use a lot of foot force tilting the bike over, as I can do most of it with simple weight transfer. But that is one of the big unknowns here. It does "feel" right tho.
Lykle

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Offline Lykle

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Re: Swift Flyer
« Reply #8 on: March 21, 2015, 02:59:11 AM »
Oh OK....Here you go, side view.

The top of my head is about 1 meter off the ground.
The main bearing tube can be seen just left of my knees. That is the tilting point.
The tube is horizontal and the whole thing will tilt along the axis formed by the rear contact patch and the tilt bearing. So one of the things I am looking forward to figuring out is, how that will behave while tilting. Will it create a jacking up effect or not.

Lykle

Design, Build and Enjoy life.

Offline Noitoen

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Re: Swift Flyer
« Reply #9 on: March 21, 2015, 04:16:57 PM »
Look at the way Toyota's trike wheels pivot to get an idea.

     


« Last Edit: March 21, 2015, 04:28:15 PM by dsquire »

Offline tom osselton

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Re: Swift Flyer
« Reply #10 on: March 21, 2015, 09:31:34 PM »
That seems like a big turning radius any tighter and the wheel would be off the ground! I wonder if the motor/rear wheel could turn with the front a few degrees to improve the radius.

Offline Lykle

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Re: Swift Flyer
« Reply #11 on: March 22, 2015, 02:54:02 AM »
Yeah the problem with tilting the front wheels completely in sync with the body is wheel scrub.
If you use conventional suspension like top and lower wishbones, the wheel needs to scrub sideways when it bumps or droops. That gives a very bad feeling to the driver, the feeling of grip is never certain.
So, to avoid that you need to use parallel swingarms, like the VW Bug front suspension. And that is ugly, hard to hide and the range of motion can be hard to achieve.
I played around with that in my first designs, when I was still thinking of building it like a car, with airco etc.
See my blog about it at http://lykle.tumblr.com. You will have to go way back tho.
With a tilter, the steering radius is often the issue.
This is why my wheels just tilt a "token" bit and use the conventional wishbone setup.
Lykle

Design, Build and Enjoy life.

Offline Lykle

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Re: Swift Flyer
« Reply #12 on: March 25, 2015, 09:10:02 AM »
Further work on the bearing stack inside the main rotating tube.
I am a bit concerned that by welding the vertical pipes, the main tube will be distorted too much for the bearings.
Also, I don't want to use thick walled tubing just for the bearing pockets. Besides, there is no way I can create an accurate bearing pocket inside the long tube of the main frame.

So I have designed a few cups to hold the bearings and these cups are welded into the main tube. They are thick enough to withstand warping. Through this all runs a 20 mm shaft that is welded to the axial bearing holder or cup.
I have 1 axial and 2 radial deep groove bearings set up.

Now, the total length of the 20 mm shaft is 200 mm, so I doubt if the front bearing will actually handle a large radial load, but this way I know for sure that it will all align.

Any comments on the design so far?
Lykle

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Offline Lykle

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Re: Swift Flyer
« Reply #13 on: April 01, 2015, 07:19:11 AM »
Next step, finalising the various components.

This is a pic of the main frame. It is changed a lot since the last image.
There is space built in for the battery pack, the bottom side rails are now curved (that will be a nice little challenge to do) and I have added an extra center rail, for stiffness. The two bottom rails on the outside alone would have been to flexible.

If I can find the right material, the frame will be made with CroMolly tubing, but I doubt if I will be able to find it here in Cyprus. Certainly not in the various dimensions I want. So I will probably have to re-design it after I find out what I can get around here.

The only real worry I now have is the front wheels. Because they do not tilt (or at least only a little) they are subject to sideways forces. Bicycle wheels are not designed to do that. So I might have to work on that. I see two possible solutions.
a) design stronger wheels, use standard components like the rim and design a wider hub with more axial load.
b) simply find stronger existing wheels, mountain bike wheels perhaps.

For the rest of the design work, it is virtually done. The only tweak I am considering for the frame is related to the hand control stalks. Currently they are welded on, but I think I will make them removable. This gives me a little more flexibility to change them in size, functionality and position later on. For instance, the throttle. It is a twist throttle, but I might want to change that to a type of joystick throttle, or a lever like in the fighter jets. Combine it with braking, forward is throttle, backwards is braking.

Ok, back to the drawing board.
 
Lykle

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Offline tom osselton

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Re: Swift Flyer
« Reply #14 on: April 01, 2015, 04:12:46 PM »
I'm wondering about that main bearing tube. It seems to me in a front impact  you will be forced into a right angle protrusion, can it be shortened for a less damaging angle?

Offline Lykle

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Re: Swift Flyer
« Reply #15 on: April 02, 2015, 01:50:13 AM »
Hi Tom,
Thank you, I had not looked at the design from the collision standpoint. Good point!

As I said, back to the drawing board.
I had a good look at it, and it is not going to be easy to improve.
Or I do a complete redesign and change the chassis completely, or I accept the fact that there is an issue and move on.
The fact is, I will not use this thing all that often, so maybe I should accept the fact.
But I am certainly going to have a good look at it and see if there is a way to mitigate it.
Once again, Thanks Tom!
Lykle

Design, Build and Enjoy life.

Offline Lykle

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Re: Swift Flyer
« Reply #16 on: April 03, 2015, 08:25:31 AM »
Thought about it.

Conclusion, this thing is dangerous.
There is no good way to protect myself when a collision occurs.

Doesn't stop me from building it though.
Lykle

Design, Build and Enjoy life.

Offline Lykle

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Re: Swift Flyer
« Reply #17 on: April 12, 2015, 01:57:47 AM »
Lot of changes recently.
I changed the main frame after I realised that I don't need the long tube sticking straight into my gut.
The frame is now stronger, but still a bit too flexible. Deflection at the front is 5 cm with 4 times the load.

Working on it, but other than increasing the tube sizes, not much I can do. Perhaps a shoulder height tube, but no smooth way to fix that at the back.

Also, I had a look at bodywork. I want something weird, not aerodynamic per se. More something that will keep my legs covered. The result is attached.
Small issue with this design is, if I hit something head on, I will be decapitated. So I will have to build in strong points and breaking points to get it to crumple correctly and keep it away from my neck.
So many issues, so much time to think about it.
Lykle

Design, Build and Enjoy life.

Offline Lykle

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Re: Swift Flyer
« Reply #18 on: April 27, 2015, 10:10:43 AM »
Chassis is now defined.
Stress levels are acceptable, deflection is still a bit large, but I do not want to make the frame higher at the back. That would be the only way to reduce the deflection. All in all, I am happy with what I have now.

The next task is the bearing pack at the front, that connects the frame to the tilting part. These bearings are doing my head in. Or I have become very stupid at my age, or I have no clue as to what I am doing. Probably simply need to sleep on it. Looking at the design examples SKF are giving me, I cannot fit any bearings to this frame. Ah well.

All the other stuff is all but done, suspension, steering, tilting (except the bearings) and electrics.

Anyway, here is a nice deflected image with stress colors.
Lykle

Design, Build and Enjoy life.

Offline Lykle

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Re: Swift Flyer
« Reply #19 on: July 06, 2015, 03:48:21 AM »
Progress has been very slow, as I am hard at work trying to find a job, but nobody is interested in a 50+ years old IT manager. Ah well, such is life these days.

The chassis is done, designed and ready to be built. Fiddled around with the bodywork. Can't get a good look in my head. It is such an unusual shape and new concept, it is hard to think of something that will look good and cover the important bits, like my balls. The V of the legs will neatly guide every little piece of debris, like stones, towards my stones. Not a way to go driving fast.
I think the real shape will only emerge after I get to see it in the metal, so to speak.

Another thing I am playing with is the hand controls. As I only use my hands for throttle and brakes, I had clip-on handlebars with a twist throttle and brake levers like on a bike. But I am now moving towards a kind of joystick, the ones that fighter jets use for throttle control. Lever, full forward is full speed, pull back and first the regenerative braking kicks in and then the hydraulic brakes start working.
I had a thought of using directional braking. Pull the stick back and to the left, the left front wheel gets more braking force than the right. Because I am throwing the "standard controls" out the window, I might as well go all the way. I would like to try it, just to see how it feels diving into a corner. But the way I designed it now, will not work as it sticks out too much and will be scraping along the road at max lean angle. Not good for the master brake cylinder!

 I am still not happy with the main tilting bearing pack. I need to make sure I have space for thermal expansion while still keeping it stiff and locked in. I think I will have a another look at it during this week. Or simply forget about it and bolt it in.
Lykle

Design, Build and Enjoy life.

Offline tom osselton

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Re: Swift Flyer
« Reply #20 on: July 06, 2015, 07:31:23 PM »
Protecting you bits is easy! Just install a man size cup holder!  :D  For the brakes I would keep them acording  to tradition and not seperated, as far as throttle it is better to have it spring loaded to return to idle that way it will not piss off on you when putting something in the car!