[python] Re: Why a Tadpole?
- From: Vi Vuong <vi_vuong@xxxxxxxxx>
- To: "python@xxxxxxxxxxxxx" <python@xxxxxxxxxxxxx>
- Date: Wed, 7 Sep 2011 18:25:57 -0700 (PDT)
Sorry, forgot the link
http://www.youtube.com/watch?v=s9qt_XZDtcM
>________________________________
>From: Vi Vuong <vi_vuong@xxxxxxxxx>
>To: "python@xxxxxxxxxxxxx" <python@xxxxxxxxxxxxx>
>Sent: Wednesday, September 7, 2011 6:13 PM
>Subject: [python] Re: Why a Tadpole?
>
>
>DW-TV clip on Hasebikes (in English)
>
>
>
>
>>________________________________
>>From: Patrick van Gompel <patrick_van_gompel@xxxxxxxxxxx>
>>To: python@xxxxxxxxxxxxx
>>Sent: Tuesday, September 6, 2011 10:49 AM
>>Subject: [python] Re: Why a Tadpole?
>>
>>
>>
>>Hasebikes uses a differential for their Kettwiesel. It seems to be a limited
>>slip differential, excellent for off-road. I was unable to find a link, but
>>saw this mentioned on a forum:
>>"Haase is using the Gommier Tricycle differential unit with an O-ring
inside to preload the spider gears. You can order them from Gommier in
Taiwan they come with axle tubes, bearings, diff, hubs, axles, and disk
brake mounts for about $100.00 US. Several of our industrial trikes at
work use the differentials. Call Lawrence at Gommeir and ask him he has
all the details about the differentials."
>>Not sure, but it might be this one:
>>http://www.arixworld.com.tw/en/products/?method=detail&aid=34
>>100$ seems very cheap. Last time I checked for differentials, they were like
>>500.
>>Freewheels might be easier/cheaper, but for tight turns it can be a nightmare
>>since the inner wheel is driven but hardly moving.
>>
>>I might be wrong, but I think that Vi means that two front wheels can be put
>>closer to the CoG because it is not limited by ones leg size. On my Python I
>>can't move my front wheel closer to the CoG because then my balls will have
>>serious problems ;-)
>>I don't have the problem that my bike tilts forward when braking, but I can
>>make the front wheel slip when pushing hard on the pedals.
>>
>>Good luck with your project Vi, I am curious about your design. Please let us
>>know.
>>I was just thinking... with two front wheels there's no more wheel flop! But
>>does that mean that now the rear part
has to flop? That would be inward of the corner for most of your body weight!
That's very good, right?
>>Patrick
>>
>>
>>
>>________________________________
>>Date: Mon, 5 Sep 2011 22:25:02 +0200
>>From: bepb@xxxxxx
>>To: python@xxxxxxxxxxxxx
>>Subject: [python] Re: Why a Tadpole?
>>
>> Hi Vi,
>>I don't think that the tadpole will allow to put the front wheels
closer to the CoG. I think the limit is more or less the same as
with the delta. If the CoG is to close to the front wheel(s), using
the front break can result in forward tilt, you might even hit the
ground with the chain wheel. Going downhill will make things worse.
>>
>>By the way, while a differential is the common solution for cars, I
think maybe a freewheel on both wheels might serve better and may be
easier to come by.
>>In fact, a differential without additional precautions, works to
have equal torsional forces on both wheels. If one wheel slips it
will take away the power from the other wheel. You get stuck if
either of the two wheels slips. This is why a serious off-road car
has differential locks.
>>
>>You are certainly right about the fairing for the delta rear wheels.
I guess either you have an enormous tail fairing or the wheels have
to go with out fairings. Or maybe with separate fairings.
>>
>>
>>Gerald
>>
>>
>>
>>On 4.9.11 21:58 , Vi Vuong wrote:
>>
>>>
>>>Hi All,
>>>
>>>
>>>Yes, let us limit ourselves to FWD and pivot turning mechanism, and leave
>>>RWD aside on its own. Tadpole front wheels can be covered by the front
>>>shell piece / fairing, while delta rear wheels cannot be covered by the
>>>sharp tail of a streamlined shell. With a differential, in case one tadpole
>>>wheel slips, the other wheel can keep going. Plus tadpole wheels can be
>>>placed closer to COG for more traction than delta wheel, especially with
>>>bigger wheels / shorter riders. I am wondering if term "reverse trike"
>>>should be clarified as FWD tadpole is like a reversed FWD delta, and vice
>>>versa with RWD tadpole and FWD delta...
>>>
>>>Yes, steering/braking is complicated with load/speed involved,
and may be just as difficult to build as FWD differential.
Regarding control, I am hopping that steering 2 wheels with my
feet would be easier than 1 delta wheel. Theoretically more may
be better, but practically less may be more?
>>>
>>>Thanks for the design primer pdf.
>>>
>>>Vi
>>>
>>>
>>>
>>>
>>>>________________________________
>>>>From: Patrick van Gompel <patrick_van_gompel@xxxxxxxxxxx>
>>>>To: python@xxxxxxxxxxxxx
>>>>Sent: Sunday, September 4, 2011 11:33 AM
>>>>Subject: [python] Re: Why a Tadpole?
>>>>
>>>>
>>>>
>>>>Interesting discussion.
>>>>Probably you guys know, but I found this document
very usefull for trike setup comparisons, steering
angles and other stuff:
http://www.hellbentcycles.com/trike_projects/Recumbent%20Trike%20Design%20Primer.pdf
>>>>
>>>>I was wondering this statement too: "With 2 front
wheels driving/steering/braking, we should get more
traction/control/stopping power."
>>>>-Not sure why 2 front wheels give better control. If
you have all the right angles for both wheels it
might, but if you have not, it probably makes things
worse.
>>>>-Nowadays any decent brake has more than enough
power to stop the wheel. So having two front brakes
instead of one wouldn't make much difference. What
does matter is where you CoG is positioned. Usually
it is easier to flip over the two front wheels of a
tadpole than over the one more foward placed front
wheel of a delta. And, having one front brake is
less complicated than having two. A lot of tadpoles
seem to suffer from 'brake turning' (or what is the
proper word?).
>>>>
>>>>Gerald, there is another thing to consider (your
last point). Although your legs bent to the inside
of the bent, your front wheel contact point goes to
the inside as well. So your CoG might actually move
to the outside of the bent. Of course that depends
on the construction of your bike and the rider.
>>>>
>>>>Patrick
>>>>
>>>>
>>>>
>>>>________________________________
>>>>From: bepb@xxxxxx
>>>>To: python@xxxxxxxxxxxxx
>>>>Date: Sun, 4 Sep 2011 19:48:40 +0200
>>>>Subject: [python] AW: Re: Why a Tadpole?
>>>>
>>>>
>>>>Hi Vi,
>>>>there is a strong point in the curiosity, no
question. Its been the reason I have been
thinking about a tadpole python myself.
>>>>
>>>>The shell for the delta somehow need to adapt to
the bending off the trike, but in which way
could a tadpole python solve this issue?
>>>>
>>>>Concerning driving I dont see where the FWD
tadpole has an inherent advantage. The
additional contact area will be nullified by the
less load per area for breaking and driving.
>>>>
>>>>
>>>>I like the considerations about the placement
off the solar pannel. In my case, I should place
the panel on the back. I generaly drive in
westery directions in the morning and easterly
coming home from work in the evening.
>>>>
>>>>There are some sources comparing tadpole vs
delta on the net, but they seem to have in
common that they focus on LWB deltas vs SWB
tadpoles.
>>>>But there are some huge differences between a
python delta and a LWB delta.
>>>>*On python trikes, the load is significant more
on the front wheel. You need this to avoid wheel
slip.
>>>>*I dont think that there is need to have the CoG
(Center of Gravity) any higher than with a
tadpole.
>>>>*On the python trike, the frontwheel actually
tilts because off the pivot angle 0~50*.
>>>>*Since the steering involves moving the legs to
the inside off the bent, weight distribution
should improve, certainly over the LWB delta,
most propbly also over the tadpole.
>>>>Maybe we need a python trike based comparison?
>>>>
>>>>
>>>>
>>>>Gerald
>>>>
>>>>
-----Ursprüngliche Nachricht-----
>>>>
>>>>Von: Vi Vuong <vi_vuong@xxxxxxxxx>
>>>>>An: "python@xxxxxxxxxxxxx" <python@xxxxxxxxxxxxx>
>>>>>Gesendet: So., 04. Sep 2011, 06:13:58 GMT+00:00
>>>>>Betreff: [python] Re: Why a Tadpole?
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>Hi Gerald,
>>>>>
>>>>>
>>>>>With 2 front wheels driving/steering/braking, we should get more
>>>>>traction/control/stopping power. Tadpole also fits nicely in a standard
>>>>>streamlined shell, http://www.youtube.com/watch?v=jETRur5Bf58, but it
>>>>>should be possible to achieve similar level of aerodynamics with advanced
>>>>>shell design for a delta...
>>>>>
>>>>>
>>>>>According to Lightfootcycles, the name tadpole came from the "wiggling"
>>>>>caused by leg movements, similar to python PSI? They also have a long
>>>>>pros/cons list, but seem to favor delta trikes (that they make)
>>>>>http://www.lightfootcycles.com/trikecomp.php Henry (Jetrike) discussed in
>>>>>depth on braking & turning, and favored the tadpole for larger tilting
>>>>>range, http://jetrike.com/tadpole-or-delta.html.
>>>>>
>>>>>
>>>>>
>>>>>Cargo / weight distribution is another good deciding factor for a delta or
>>>>>tadpole. If the load is a large flat solar panel in my case, it seems
>>>>>that placing it up front would give better weight distribution for a FWD.
>>>>>Plus having the electric motor in the rear tadpole wheel may be simpler
>>>>>than in front delta wheel.
>>>>>
>>>>>
>>>>>Last, the curiosity factor of building a tadpole is huge :) with
>>>>>possibilities of sharing frame/module with a exiting bike or delta trike.
>>>>> Yep, the Guinea Pig needs one more module to go from bike to
>>>>>delta/tadpole/quad, http://www.youtube.com/watch?v=0cy50C1Lhjw
>>>>>
>>>>>
>>>>>Cheers,
>>>>>
>>>>>
>>>>>Vi
>>>>>
>>>>>
>>>>>
>>>>>>________________________________
>>>>>>From: Gerald <bepb@xxxxxx>
>>>>>>To: python@xxxxxxxxxxxxx
>>>>>>Sent: Friday, September 2, 2011 11:27 AM
>>>>>>Subject: [python] Why a Tadpole?
>>>>>>
>>>>>>
>>>>>>
>>>>>>Hi All,
>>>>>>It is not that I
like to discourage
creativity -
inspired by your
ideaes, I have
been thinking
about a tadpole
python design
myself.
>>>>>>
>>>>>>But actually what
specific advantage
one like to gain
from the tadpole
python design?
Just to have
something to aim
for.
>>>>>>
>>>>>>Gerald
>>>>>>
>>>>
>>>>
>>
>>
>>
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