Slow new quad build.

[Trickytrike]

Thanks for the interesting thread, I have found very little about designing a quad, not for racetrack but everyday allrounder.

It is nice that it can be shorter than a tadpole trike.

I guess for a given turning radius, SWB allows for less steering angle so wheels a bit closer to the frame and less leverage on the kingpins ?

Do you need suspension on a quad vs tadpole trike, as you are "between" the backwheels so road camber / potholes will shake you from side to side ?

On a trike I notice the monotube frame and front boom tend to twist a bit to adapt to the road surface, so would a quad be harder

 

[stormbird]

Thanks for the interesting thread, I have found very little about designing a quad, not for racetrack but everyday allrounder.

I ain't no designer just trying my best to get something usable within my parameters.

It is nice that it can be shorter than a tadpole trike.

If space is at a premium and you don't need it's extra length for hauling stuff

I guess for a given turning radius, SWB allows for less steering angle so wheels a bit closer to the frame and less leverage on the kingpins ?

The race car had 7" cut from between the wheels made a big difference to the turn radius , however no having raced it before the surgery I cannot be certain the handling had not been adversely effected ?

Do you need suspension on a quad vs tadpole trike, as you are "between" the backwheels so road camber / potholes will shake you from side to side ?

Down to personal preferences surface conditions and speed ?
Maybe it could be argued a lighter vehicle will have a better ride than a heavier one ?

On a trike I notice the monotube frame and front boom tend to twist a bit to adapt to the road surface, so would a quad be harder

The race car was extremely stiff and it was possible to get only 3 wheels on the ground , usually when traversing camber so not dangerous.
The first race car had suffered from to many race circuits with tight right hand corners and so when unloaded i.e me not on board , sat with left front wheel almost touching the floor

Seen this

Paul

 

[stormbird]

So I want to run this passed you ?

A sketch of 3 possible transmission systems and how choosing one of the other further influences your control options ?
So drawing labeled Apollo cars is the most common system where the chain has to pass under the seat to reach a rear cassette on either a 1WD or 2WD axle.
Now this tends to increase the length of the car as there has to be room under and behind the seat for the chain to get back to axle height and have enough distance for the chain to shift along the cassette.
This also limits the seat height as pulleys maybe large in diameter and we still need about 3" of ground clearance [ if we drive real real carefully ]
It is usual to have side stick controls with this configuration [ this makes it easier to get in the car ]

So drawing labeled Royce cars is the next most popular system here there are 3 chains and a lay-shaft in front of the seat carrying the cassette.
This can result in a very short car and maybe a lower car if your body parts are not attacked by the cassette or chain.
These style of cars usually have a steering column running down the centre of the car and very short handle bars so there is no chain interference
however the handle bars sit close to the seat and so getting in and out means sitting on the seat OR making the column telescope inwards for getting in [ this is hard due to the cables , which generally are longer the the Apollo style controls ]

So drawing labeled ' Possible other way ' shows a sort of pedalo arrangement with custom pedals and bottom bracket and initial drive chain running down one side [ or the other ] of the chassis and inside or outside the chassis. Whilst it has been considered and examples built there are to many specialist parts for it to be considered now [ it would slow this whole build , and there have been more than it's far share of dead ends already ! ]

This shows how the differences outlined above can result in quite different looking cars.
My obsession with getting in and out of tight spaces draws me to the yellow Royce car [ although this is a little cheat as that car is to short for me by about 4" ] rather than the longer gray/black Apollo car [ my car 45 is more like this ]

My preferred option ? Royce transmission with Apollo steering , can it be done ? no idea yet

Paul

 

[Trickytrike]

I remember seeing photos the pedalo style one built on a finnish forum, with 1wd and chain outside the frame, so freeing up the space in the center for low riding position. Building the crankshaft style pedals contraption sounds like an undertaking on its own, considering torsional flex required ?

https://flic.kr/p/2eayZ1u

Your idea sounds good, hope it can be built - using the "figurouter" tool as you go.

No rest for the wicked ...

 

[stormbird]

This was removed from a track last year after 3 incidents involving it as the handling [ with younger riders ] was putting them and others at risk !

Also for such a short w/b the rider was sat to high !

It could be a tadpole trike converted to a quad ?

Paul

 

[undertoad]

I think you'd need a nose job, if you hit the front brakes hard

 

[Trickytrike]

A small wheel under the nose maybe ?

 

[undertoad]

Works for airplanes

 

[stormbird]

Best guess is a w/b between 28" & 30" , my current plan is for 40" and 44" if I need more stability

Paul

 

[Popshot]

This shows how the differences outlined above can result in quite different looking cars.

My preferred option ? Royce transmission with Apollo steering , can it be done ? no idea yet

Paul

I don't think those pictures show any real difference. In both, the rear wheels are level with the driver's head. I concede that the Royce system can have the rear wheels further forward but it's not shown there. The grey one has a lot of body behind the driver and the driver is male and therefore almost certainly taller than the female in the yellow so the wheelbase is necessarily longer.

I see no reason why you can't have tank steering with a Royce style drive. It just needs enough extra thought at design to make things miss each other.