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  #11  
Old 05-03-2019, 09:23 AM
Canadian_JOY Canadian_JOY is offline
 
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Ummm... (Select flame mode ON... In keeping with the primer wars...)
I didn't see any primer on those parts. Shouldn't you prime them first? :-) :-)

Beautiful project.

Which Lycoming will it accommodate?
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  #12  
Old 05-03-2019, 11:23 AM
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Sam Buchanan Sam Buchanan is offline
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Default Wow!

A genuine work of art! Display it on the wall when you aren't riding it.
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  #13  
Old 05-03-2019, 11:34 AM
drdriddle drdriddle is offline
 
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You should license this through Vans. First you order and do the the tool box to get the skills to do the bike... then you order the bike to hone the skills to do the plane. Its the logical step between box and plane.
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  #14  
Old 05-03-2019, 11:37 AM
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ppilotmike ppilotmike is offline
 
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Quote:
Originally Posted by drdriddle View Post
You should license this through Vans. First you order and do the the tool box to get the skills to do the bike... then you order the bike to hone the skills to do the plane. Its the logical step between box and plane.
I like this! Cool project. I too am interested in what it weighs and whether or not it folds. Nicely done!
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  #15  
Old 05-03-2019, 01:27 PM
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Quote:
Originally Posted by drdriddle View Post
You should license this through Vans. First you order and do the the tool box to get the skills to do the bike... then you order the bike to hone the skills to do the plane. Its the logical step between box and plane.
That progression would make more sense if the bike fit in the plane....
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  #16  
Old 05-03-2019, 01:43 PM
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DanH DanH is offline
 
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Quote:
Originally Posted by maniago View Post
That progression would make more sense if the bike fit in the plane....
Thomas, with just a little tweaking, I think you have a market for plans sales....
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  #17  
Old 05-03-2019, 02:00 PM
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DeltaRomeo DeltaRomeo is offline
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Thumbs up Jaw. On. Floor.

I agree with others that a) this is a beautiful bike and b) I bet plans would sell.

Simply beautiful!

v/r,dr
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  #18  
Old 05-03-2019, 03:06 PM
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Guy Prevost Guy Prevost is offline
 
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Brilliant! My two favorite things are Airplanes and Bikes!
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  #19  
Old 05-04-2019, 04:59 AM
Thomas Lukasczyk Thomas Lukasczyk is offline
 
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Thanks guys,

well the idea is not entirely new, and it is not my idea either. That was something I had not discovered until I was far into the design process. Essentially, there are many materials that can be used to build a bike. However, two managed to stick out in the mountain bike world. Those are either layups of carbon fiber or welded Aluminum tubes. I do not want to start the big debate about the never ending “reduce weight at all cost” philosophy. It seems people are trying hard to reduce the frame weight of a bike to zero. From the natural science point of view, that is a story without a happy end.
Of course lightness is important and I am the last person who denies that. I know quite well what it means to carry, or not to carry, three extra pounds uphill on a cross-country race.
Anyway the most effective method to reduce frame-mass is not picking the right material or perfecting shape and quality. It is cutting down your bike's abilities. That is definitely a path that I am not going to ride on.
I have worked a lot with carbon fiber and I am fully aware of the fact, that this material offers the best strength by density ratio. It is also stiff like nothing else.
There are some applications where this material is simply superior and therefore the best choice.
Yet, I do not consider a bike frame as one of them. If you are ready to sacrifice every disadvantage on the low weight altar, carbon fiber is for you. If you are ready to treat your bike like a musician treats his violin and you do not mind handling it like a raw egg, carbon fiber is for you.
But I am old school, I like vintage cars, rock'n'roll and cold beer served in glasses. Riding a plastic bike is simply not something I consider attractive. My bike is parked, not hung, in the garage next to the lawn mower. My kids my accidentally drop stuff on it and I can not help the fact that it will potentially be buried under a stack of garden tools. When I am shredding down a gravel road in the forest, I can hear little rocks bouncing off the frame and I simply do not want to constantly ask myself “is that going to be a strength problem?” Failures with carbon occur suddenly and without any warning. These structures do not bend, and they do not absorb energy. They simply snap.
My goal was to develop a cross country mountain bike frame that can withstand the bending moments of any fork available. I wanted to rely on structure that simply takes all loads induced by a heavy rider.
Frame weight is only a small part of the total bike weight. So I thought a stiff and strong, lasting practical-all day-abuse frame can be built with only a little mass penalty.
I was always inspired by Aircraft aluminum. Having built and flown two RVs made of that beautiful material, provided the required hands on experience. Working is fun and passionate, calculations and assumptions become reality while you are trying something new. That is what this is all about.

Alloy bike frames are usually made from welded tubes. One of the strongest weldable aluminum-alloys that is out there is 6061-T6. Most Aluminum alloys do roughly have the same density. That means everybody is pretty much stuck there, although it is not considered “high strength alloys”. It's fatigue resistance is moderate, and it does not corrode easily. It is also used on aircraft a lot and by no means inferior. If you melt Aluminum, for example during welding, a lot of strength and fatigue resistance is lost. Some of that can be restored by a special heat treatment afterwards, but you never get it back completely. The weld seam will always be the weak spot. It is a stress riser that suffers from a disturbed metal microstructure and the increased cross section that usually comes along with it, can’t compensate that completely. All the broken aluminum bike frames that I have ever seen either cracked or started cracking at a weld.
A typical aircraft alloy is 2024-T3. It is somewhat stronger than 6061-T6 and more importantly, it fatigues far less. That means the given forces and loads may create more tension and therefore require less material and weight to be bared. High strength aluminum alloys are generally not weldable, and the sheets need to be joined with rivets. Rows of rivets are no weak spot talking fatigue and the offer some other advantages. It is possible to create stacks of reinforcements wherever needed. That feature offers a lot of flexibility and enables the designer to create exactly the cross sections that are ideal at a given part of the frame. Moreover, the thickness of the sheets can be varied, creating strong flanges and weak webs. That is a common and extremely weight effective practice when building aircraft structures. The moment of inertia that can be achieved with a certain amount of material for a certain cross section is much higher that way. That clearly is a technical advantage that simply is not there if tubes or similar extruded shapes are used.
A riveted structure offers even more advantages. Parts that need to be exceptionally strong or demand high surface toughness, can be made from other materials. The Steering-tube and the bottom bracket can potentially be fabricated from high strength aircraft grade steel.
Taking a technical view, there is no such thing as a win-win situation. It is all a big trade off and the engineer must come up with the best specific balance. Of course, there are disadvantages building a bike like that. Riveted connections require certain overlaps of the material and they add weight while not always increasing strength or stiffness. High grade aluminum alloys do corrode quite easily and ask for some additional protection. This problem can be cured by the Alclad feature that is available for some sheet-thicknesses. Another and probably the most severe drawback of building a bike from aircraft sheet metal is the time involved, sure RV-builders know that. This effectively prevents such a frame from ever entering the marked and I am convinced it is the main reason why we have not really seen this before.

Many people have asked me about the weight of the frame. I do hesitate to simply throughout a number that in the end is somehow supposed to rate the degree of success. I feel like that will not do it justice.
Let me give you an engineer’s-answer, not a salesman’s-answer. It is stronger, stiffer and more fatigue resistant than any welded aluminum MTB-frame of equal weight, that I know.

Total bike weight: 23 lbs (I did not use the lightest components available, I wanted quality)

The bike was designed around me, so frame-size and geometry will simply not fit everybody. It is really a good idea to offer plans then?

It runs great, climbs like nothing else and I am beating my personal best (and that of others) on my weekly circle every time I try. It is fast, super stiff and so much fun.


regards

Thomas

Last edited by Thomas Lukasczyk : 05-04-2019 at 05:11 AM.
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  #20  
Old 05-04-2019, 05:11 AM
RV7ForMe RV7ForMe is offline
 
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Does is come pre punched?
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