Downstairs Toilet and Soil Pipe Bends

Hello

I'm in the process of fitting a downstairs toilet and the installation of the soil pipe and I'm just thinking about what I need, does this sound okay?

Soil pipe straight through the wall from the toilet and vertically down with an inspection elbow, then immediately connect a long radius elbow to take it horizontally a distance of 1.6m and then another long radius elbow to take it through 90 degrees and then 4.5m straight into the top of the sewer chamber.

Obviously I know 90 degree elbows aren't good that's why the use of long radius elbows to achieve a better flow, the main soil pipe for the upstairs toilet enters this sewage chamber which should provide the ventilation. It's impractical to connect the new soil pipe to the existing one.

Any ideas?

Thanks

 

Thanks, just what I wanted to hear.

 

Would I get away with replacing the first long radius elbow with a standard elbow?

So soil pipe through wall from toilet, 90 degree elbow pointing it down, then immediate 90 degree elbow taking it horizontally 1.6m and then change direction using a long radius 90 degree elbow to 4.5m into the sewage chamber.

The reason for doing it this way would be just to make it look neater above ground having a standard elbow instead of a long radius one.