[python] AW: Re: Why a Tadpole?
- From: Gerald<bepb@xxxxxx>
- To: python@xxxxxxxxxxxxx
- Date: Fri, 9 Sep 2011 08:09:16 +0200
Hi,
Yes, that looks particular nasty. That's why one wants a low CoG.
Gerald
-----Ursprüngliche Nachricht-----
Von: "dirk@xxxxxxxxxx" <dirk@xxxxxxxxxx>
An: python@xxxxxxxxxxxxx
Gesendet: Do., 08. Sep 2011, 06:52:50 GMT+00:00
Betreff: [python] Re: Why a Tadpole?
Hi Vi,
nice Video, especially the last second! A raised position without enough lean
steer and the bike falls over...
the kettwiesel seems to work as a delta because the riders sits way back with
his cog near the axle/two wheels - and since this axle is favoured through
wheight distribution, it is the driven one.
I case of a python setup a driven front seems more attraktive from this point of
view, so a tadpole setup seems to be the right choice.
My complicated lean steer idea was to have a central drive train (typical
python) that is distributed to either side with a rigid cross beam(including
differential) and then instead of mounting the two driven wheel directly to this
cross beam, have them connected like a suspended rear wheel on a backward
pointing leaver. In order to allow lean steer, the two leavers would be attached
to a downwardpointing string on the other end, that runs U-shaped across to the
other wheel. If you pull that string left/right you can adjust the leaning. In
order to stay U-shaped, that strin obviously needs to be guided by another cross
beam.
The rest of the original python design could be kept as it is.
This is somewhat the solution of henrys delta the other way round to make it a
delta and keep stearing and leaning independend. Instead of rigid guiding rods,
i came up with the string idea when i realised that a) paraglider-strings a very
tought, take enormous loads per cross section and are stiff and b) you could
have a suspension/damping unit between either side to combine lean steer and
suspension into one - all within a light setup.
I did not have the chance to try this out yet.
greetings,
DirkS
Vi Vuong <vi_vuong@xxxxxxxxx> hat am 8. September 2011 um 03:25 geschrieben:
> 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
> >>>>>>
> >>>>
> >>>>
> >>
> >>
> >>
> >
> >
http://dirk.steuwer.de
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