Sunday evening will be the soonest I'll be at the desktop.
Delta trike design - constraints and solutions ?
- Thread starter stormbird
- Start date
Popshot
Don't spend anytime at it , it is only a whim , it will keep DannyC's idle hands busy ...
Paul
I have a feeling that the Eland sheet does all that malarkey and shows it in the output cells along with the % of variance from perfection.Popshot
thanks for the offer , in the picture it is w/b 31" track 31" [ well as near as I can get ! ]
I was hoping to nudge DannyC to make a spreadsheet [ he really likes that]
Paul
As you don't have a frame with all the required info/reference points it would be difficult to do or to guess at, but you could plan the steering out on the sheet and then build to that.
Eland says within 10% of perfect is good enough for all but the impossible tight turns.
See here where for a turn of a given radius (100,000 to 2,000 mm) it shows the differing wheel turn angles for the inner/outer wheels.
Around 28 degrees with a 134" circle
Popshot
Thanks , that's a big difference to the inner wheel !
So got all excited though I had a plan ?
post #130 I looked at using 2 x BMX frames for a quick and dirty quad however they were 38" w/b that would have made the quad to big to fit in the car and @ 25' raise the radius of the turning circle from 64" to 81" possible to much.
However Wednesday and wrestled from the clutches of the scrap metal men a 20" front suspension MTB almost identical to the one Dale Rider gave me , would they be better ?
Certainly @ 34" w/b I stood more of a chance getting it into the car and the turning radius @ 25' went from 64" to 73" maybe livable ?
So here they are @ 28" track and 34" w/b not so square now !
Now as luck would have it the one piece BB when removed yielded a 50mm[ish] hole in both frames that I happen to have some pipe that was a great fit.
So blue lines represent new tubing 3 lines show 50mm through BB holes , could pick up front seat mount and main spar out towards BB and pedals.
Blue line near axle another tube connecting rear end together upper seat mount could probably go down to where they are welded to frame chain stays, no triangulation shown probably needs some.
Front very messy I think my knees pass the head tubes so no simple straight across coupler , blue line shows it going forward before crossing front of quad.
3 x blue lines again 50mm[ish] tube connecting BB holes and short main spar off to pedals and a joining piece main spar to front extension.
Green shows connection between forks for steering [ Ackerman place ] and possible position of a steering control , this would make all the cables very long !!!
Easy you say , make it tank steering , very short cables , however it is hard enough to get in it as shown ?
You cannot back into it like a tadpole and seat post in frame makes it already hard to climb over without having some control levers in way.
Also not shown is any chain routing/jackshaft etc etc.
It seems to have all the bad points of a mono boom combined with all the bad points of a peripheral frame and apart from not needing kingpins and having perfect centre point steering it is a shed load of work and will be very heavy.
So disappointed I go to lay my weary head.......
maybe tomorrow will bring some bright ideas ?
Paul
Thanks , that's a big difference to the inner wheel !
So got all excited though I had a plan ?
post #130 I looked at using 2 x BMX frames for a quick and dirty quad however they were 38" w/b that would have made the quad to big to fit in the car and @ 25' raise the radius of the turning circle from 64" to 81" possible to much.
However Wednesday and wrestled from the clutches of the scrap metal men a 20" front suspension MTB almost identical to the one Dale Rider gave me , would they be better ?
Certainly @ 34" w/b I stood more of a chance getting it into the car and the turning radius @ 25' went from 64" to 73" maybe livable ?
So here they are @ 28" track and 34" w/b not so square now !
Now as luck would have it the one piece BB when removed yielded a 50mm[ish] hole in both frames that I happen to have some pipe that was a great fit.
So blue lines represent new tubing 3 lines show 50mm through BB holes , could pick up front seat mount and main spar out towards BB and pedals.
Blue line near axle another tube connecting rear end together upper seat mount could probably go down to where they are welded to frame chain stays, no triangulation shown probably needs some.
Front very messy I think my knees pass the head tubes so no simple straight across coupler , blue line shows it going forward before crossing front of quad.
3 x blue lines again 50mm[ish] tube connecting BB holes and short main spar off to pedals and a joining piece main spar to front extension.
Green shows connection between forks for steering [ Ackerman place ] and possible position of a steering control , this would make all the cables very long !!!
Easy you say , make it tank steering , very short cables , however it is hard enough to get in it as shown ?
You cannot back into it like a tadpole and seat post in frame makes it already hard to climb over without having some control levers in way.
Also not shown is any chain routing/jackshaft etc etc.
It seems to have all the bad points of a mono boom combined with all the bad points of a peripheral frame and apart from not needing kingpins and having perfect centre point steering it is a shed load of work and will be very heavy.
So disappointed I go to lay my weary head.......
maybe tomorrow will bring some bright ideas ?
Paul
There is a way to utilise tank steering without a drag link, and it's largely the drag link that's the bit in the way. Something like this between one steering shaft and the other should in theory do the job though I wonder if slop and flex would in reality make it impractical.
Popshot
Not got anywhere near thinking of drag links
I can't climb over the frame ! the seat masks the lowest part as you go forward the frame only gets higher !
The green is probably where the tank steering levers would need to be only adding to the problem.
So cut out the red bit and add a blue bit would help a little ...
It seems to have all the bad points of a mono boom combined with all the bad points of a peripheral frame and apart from not needing kingpins and having perfect centre point steering it is a shed load of work and will be very heavy.
So disappointed I go to lay my weary head.......
maybe tomorrow will bring some bright ideas ?
... and it has , now looking at peripheral frame builds , pedal cars are a starting point.
Wonder where this will lead ?
Paul
Not got anywhere near thinking of drag links
I can't climb over the frame ! the seat masks the lowest part as you go forward the frame only gets higher !
The green is probably where the tank steering levers would need to be only adding to the problem.
So cut out the red bit and add a blue bit would help a little ...
It seems to have all the bad points of a mono boom combined with all the bad points of a peripheral frame and apart from not needing kingpins and having perfect centre point steering it is a shed load of work and will be very heavy.
So disappointed I go to lay my weary head.......
maybe tomorrow will bring some bright ideas ?
... and it has , now looking at peripheral frame builds , pedal cars are a starting point.
Wonder where this will lead ?
Paul
Paul & I have been trying to work out the trade-off's of wheel-base/Track and turning angles.
My approach is theoretical and spreadsheet based, Paul is more practical physical model based.
I think this approach may work well because Paul can check and validate the theoretical model.
The latest spreadsheet provides a way of checking wheel-angles for radius turns and varying wheelbases and track widths.
Copy available on request.
My approach is theoretical and spreadsheet based, Paul is more practical physical model based.
I think this approach may work well because Paul can check and validate the theoretical model.
The latest spreadsheet provides a way of checking wheel-angles for radius turns and varying wheelbases and track widths.
Copy available on request.
Ok so time to reassemble the delta quad mock-up and make some improvements , first up raise the pedals 1.5" this now puts the pedals @ 17.5" from the floor and the front of the seat 14" from the floor a comfy difference. This then meant the front boom could move forward 1.5" so moving the wheels forward by that amount.
Boom not yet move forward however my DIY wheel stand was pressed into service to see how much width my feet/legs needed to pedal.
Looks very workable and you can just see the front boom @ the bottom of the picture [ pre-move ] with 3" of heel clearance.
I built a new boom and attached it 1.5" forward and added some forward extensions to move the wheels further forward , here as a quick fix I just clamped the whole of the old front boom complete with pedals etc to the new boom. The black hatched line can be remove to give heel clearance [ although I can almost pedal as it is now ]
Now have a wheel base of 34" so front wheel now about level with the chain rings , nice
Of course I only built it with these right angles because the brackets joining the wood together are 90' , in steel I wondered if I could cut the corner and still get my steering angles ?
So the red plastic push stick shows where a single piece of square box may replace the 2 part wooden dog leg ?
A before I close the door shot , showing the wheel would never hit a angled piece of steel where the red plastic is.
This picture also highlights another problem to be tackled ? the wheel turn angle is impressive however the wheel has now turned beyond the control arm reach should I
use side stick steering ?
Assume the blue control arm is for the Ackerman [ almost gone over centre and very near the heels ?
Red is steering control arm and green is to side stick levers ?
Both fails !
I may have to implement something like this to get the most out of the available angles ?
So a head tube either through of alongside the main keel and the steering arm underneath the centre , will need 1 or 2 U/J's and some form of extending/retracting steering controls to allow entry and exit. This solution does make the brake/gear cables much longer than side stick steering.
Any better ideas ?
Paul
ps would not say I am pushing the envelope with this ? more severely distorting a rectangular box
Boom not yet move forward however my DIY wheel stand was pressed into service to see how much width my feet/legs needed to pedal.
Looks very workable and you can just see the front boom @ the bottom of the picture [ pre-move ] with 3" of heel clearance.
I built a new boom and attached it 1.5" forward and added some forward extensions to move the wheels further forward , here as a quick fix I just clamped the whole of the old front boom complete with pedals etc to the new boom. The black hatched line can be remove to give heel clearance [ although I can almost pedal as it is now ]
Now have a wheel base of 34" so front wheel now about level with the chain rings , nice
Of course I only built it with these right angles because the brackets joining the wood together are 90' , in steel I wondered if I could cut the corner and still get my steering angles ?
So the red plastic push stick shows where a single piece of square box may replace the 2 part wooden dog leg ?
A before I close the door shot , showing the wheel would never hit a angled piece of steel where the red plastic is.
This picture also highlights another problem to be tackled ? the wheel turn angle is impressive however the wheel has now turned beyond the control arm reach should I
use side stick steering ?
Assume the blue control arm is for the Ackerman [ almost gone over centre and very near the heels ?
Red is steering control arm and green is to side stick levers ?
Both fails !
I may have to implement something like this to get the most out of the available angles ?
So a head tube either through of alongside the main keel and the steering arm underneath the centre , will need 1 or 2 U/J's and some form of extending/retracting steering controls to allow entry and exit. This solution does make the brake/gear cables much longer than side stick steering.
Any better ideas ?
Paul
ps would not say I am pushing the envelope with this ? more severely distorting a rectangular box
Do you really need all that amount of wheel turn? 16 inchers may give the extra clearance. A uj operating at such a steep angle is going to be very heavy. Bevel gears, a steering box or rack and pinnion would be better IMO. You could bring the steering arms high, over the tyres or low under them. Given the physics of pivot points etc, high is the more physically likely though may impact on getting on and off.
Simple answer is I don't know , however building it knowing I have lost half the steering to the control mechanism would seem a little short sighted ?
If I found I had to little steering out on the street getting more would be a major headache ?
I would probably choose a pair of steering u/j's , only lighter than your Prius ones !
I will work on the mock-up to get rid of the clamps and front piece in the way , then I will have a better idea what space is available.
More likely to make getting the feet over them to reach the pedals impossible .
Still I am happy with the way it is going , just a few bit's of wood heading for the stove , proving very useful
Paul
So cleaned up the front end to get this :-
first up room for my heels inside the step
Of course the wood dog leg can be replaced by steel following the path of the overlaid stick , still room to get on seat and clearance for the heels.
and does not impeded wheel at maximum turning radius.
So look at making a better kingpin and add some arms and rods for linking wheels/Ackerman etc
Paul
first up room for my heels inside the step
Of course the wood dog leg can be replaced by steel following the path of the overlaid stick , still room to get on seat and clearance for the heels.
and does not impeded wheel at maximum turning radius.
So look at making a better kingpin and add some arms and rods for linking wheels/Ackerman etc
Paul
The last picture is looking reminiscent of my original Street-Fox cross-boom arrangement, That chap Brad knows a thing or two!So cleaned up the front end to get this :-
first up room for my heels inside the step
Of course the wood dog leg can be replaced by steel following the path of the overlaid stick , still room to get on seat and clearance for the heels.
and does not impeded wheel at maximum turning radius.
So look at making a better kingpin and add some arms and rods for linking wheels/Ackerman etc
Paul
Yes I am sure it is the same parts arranged in a different order !The last picture is looking reminiscent of my original Street-Fox cross-boom arrangement, That chap Brad knows a thing or two!
I think the kingpin/axle will be in a different place , and to make thinks simpler [ for my simple mind ] there will be no fancy boom angles !
Paul
After a conversation with DannyC this morning and a lack of garage time I decided to just muse over 2 threads ?
1) could I have rear suspension [ please ]
This might be a simple way to achieve it , spread the forks for a rear wheel [ with a free wheel ] pivot the fork to the left of the elastomer and use the elastomer as a suspension element ?
2) Use a IGH as a mid-drive ?
Well this seems mighty close to the ground [ 3.5" ] however I measured the main boom and it's underside is only 9.5" from the ground so plenty of scope to get this higher me thinks.
So learned a little and have some further thinking to do.
Paul
1) could I have rear suspension [ please ]
This might be a simple way to achieve it , spread the forks for a rear wheel [ with a free wheel ] pivot the fork to the left of the elastomer and use the elastomer as a suspension element ?
2) Use a IGH as a mid-drive ?
Well this seems mighty close to the ground [ 3.5" ] however I measured the main boom and it's underside is only 9.5" from the ground so plenty of scope to get this higher me thinks.
So learned a little and have some further thinking to do.
Paul
So rear suspension ?
How hard can it be .......
Well very by the looks of it , mainly caused by the rear wheels being further forward than on a normal delta/quad [ to get it as short as possible ]
to implement normal Python rear wheel suspension [ documented on Jurgen's original build ] I would have to pivot this fork and provide somewhere for the elastomer to be mounted ?
It would look like this so plenty of frame to the left of the fork stem , right in the area I need to get in and out of the seat !
It would be much better if the suspension was behind the seat ? with the wheel moving up and down ?
So dragged the bike frame out and attached the fork turned through 90'
The piece of wood holding the wheel would be a piece of rectangular tubing welded to the moving part of the fork between the legs and the brake bridge would be cut off.
Welding the rectangular tube up the fork legs also shortens the forks putting the head tube at the same height as the rear seat mount [ good ]
If I chopped the upper frame tube off and the seat tube and chain stays leaving the BB shell it could be joined to the other side with some round tube I have picking up the front seat mount.
Then joining the head tubes together and picking up the rear seat mount it would be a self contained rear suspension rear end ?
The BMX wheel would each have a free wheel driven by a chain passing the seat to a jack shaft under the seat[ ish ]
Of course there is some extra weight however the fact the forks could still turn would allow them to be connected to each other by a adjustable rod which would allow the rear tracking to be adjusted ? [ maybe ]
This would be a lighter way of doing it throwing the kids bike frame away and making all the parts it supplied with tubing ?
More though needed.
Paul
How hard can it be .......
Well very by the looks of it , mainly caused by the rear wheels being further forward than on a normal delta/quad [ to get it as short as possible ]
to implement normal Python rear wheel suspension [ documented on Jurgen's original build ] I would have to pivot this fork and provide somewhere for the elastomer to be mounted ?
It would look like this so plenty of frame to the left of the fork stem , right in the area I need to get in and out of the seat !
It would be much better if the suspension was behind the seat ? with the wheel moving up and down ?
So dragged the bike frame out and attached the fork turned through 90'
The piece of wood holding the wheel would be a piece of rectangular tubing welded to the moving part of the fork between the legs and the brake bridge would be cut off.
Welding the rectangular tube up the fork legs also shortens the forks putting the head tube at the same height as the rear seat mount [ good ]
If I chopped the upper frame tube off and the seat tube and chain stays leaving the BB shell it could be joined to the other side with some round tube I have picking up the front seat mount.
Then joining the head tubes together and picking up the rear seat mount it would be a self contained rear suspension rear end ?
The BMX wheel would each have a free wheel driven by a chain passing the seat to a jack shaft under the seat[ ish ]
Of course there is some extra weight however the fact the forks could still turn would allow them to be connected to each other by a adjustable rod which would allow the rear tracking to be adjusted ? [ maybe ]
This would be a lighter way of doing it throwing the kids bike frame away and making all the parts it supplied with tubing ?
More though needed.
Paul
Ok suspension part 2
This is a better model to copy than the Python example , keeps every part underneath the pivot and so my arms/hands etc.
Much easier to change spring values and may with some fiddling work with either elastomers or springs.
First though is a couple of front forks widened for rear wheels and with a hole drilled and tube inserted underneath the hole for the brake/mudguard , shown in the picture is a white fork 20" can't be done as tyre would brush against it.
I have some 24" forks [ Yellow ] and there is room for a tube however red line shows how much longer than the white ones even if cut off at the crown base of the yellow one.
Also rod end bearings would be a long way from jackshaft mounting frame.
This looks more promising and be triangulated better ?
So wood represents 4" top part would be cut off at rear and some of the shaded area removed till it sat on the wooded block , welded back in and gap filled with steel where it was removed. Both can then be cut free from remaining front half and extra tubes added on the sides to join them and a pivot tube added across the top as in the picture at the top of the post. Then below I image 3mm right angle welded between legs with part hanging down and that triangulated to the underside of the chain stays , the mount for the control rod.
Although I don't relish doing this twice !
Might work...
In an attempt to get some useful data from the mock-up re-turning circle I have remade kingpins like this , both sides.
I need to take off cross boom and try and figure out how to calibrate them and add a static pointer to frame so I can read off angles , marking are @ 5' and 10'
Then remount cross boom with a 1.5" spacer to raise the main boom.
all the best Paul
This is a better model to copy than the Python example , keeps every part underneath the pivot and so my arms/hands etc.
Much easier to change spring values and may with some fiddling work with either elastomers or springs.
First though is a couple of front forks widened for rear wheels and with a hole drilled and tube inserted underneath the hole for the brake/mudguard , shown in the picture is a white fork 20" can't be done as tyre would brush against it.
I have some 24" forks [ Yellow ] and there is room for a tube however red line shows how much longer than the white ones even if cut off at the crown base of the yellow one.
Also rod end bearings would be a long way from jackshaft mounting frame.
This looks more promising and be triangulated better ?
So wood represents 4" top part would be cut off at rear and some of the shaded area removed till it sat on the wooded block , welded back in and gap filled with steel where it was removed. Both can then be cut free from remaining front half and extra tubes added on the sides to join them and a pivot tube added across the top as in the picture at the top of the post. Then below I image 3mm right angle welded between legs with part hanging down and that triangulated to the underside of the chain stays , the mount for the control rod.
Although I don't relish doing this twice !
Might work...
In an attempt to get some useful data from the mock-up re-turning circle I have remade kingpins like this , both sides.
I need to take off cross boom and try and figure out how to calibrate them and add a static pointer to frame so I can read off angles , marking are @ 5' and 10'
Then remount cross boom with a 1.5" spacer to raise the main boom.
all the best Paul
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I'd suggest springs over elastomers for that type of suspension. Springs will give potentially more movement (you don't have to allow that extra movement if undesirable) and will also allow preload to be added which will allow some dialling out of both sag and roll. Springs will allow the best rate to be more easily found and probably cheaper too.
It's a bonus that both springs and elastomers will work with it , I have a selection of springs however not many in pairs.
It's early days but knowing what to build and how is half the battle.
Paul
Hi all
So have given this some though :-
This had problems ?
Drops facing forward not needed and made it longer than needed.
hard to make a strong joint of the pivot
hard to make a strong joint for the operating arm
just to many pieces
I decided there was that much work for little gain I was better starting from scratch ?
So this is a lot better solution , strong where it needs to be [ easy clean !!! ] and a solid mount for the pivot.
Cannot figure out spring location/mount or spring operating arm till further down the line , however it is currently plan of choice [ how many times have I said that ! ]
Paul
So have given this some though :-
This had problems ?
Drops facing forward not needed and made it longer than needed.
hard to make a strong joint of the pivot
hard to make a strong joint for the operating arm
just to many pieces
I decided there was that much work for little gain I was better starting from scratch ?
So this is a lot better solution , strong where it needs to be [ easy clean !!! ] and a solid mount for the pivot.
Cannot figure out spring location/mount or spring operating arm till further down the line , however it is currently plan of choice [ how many times have I said that ! ]
Paul