Changing the steepness of a parametric equation

Question

I have a working Octave script the creates a spiral

Script:

clc
close all
clear all

u=linspace(0,4*pi,100);
v=linspace(0,pi,100);
[u,v]=meshgrid(u,v);
x=u.*sin(u).*cos(v);
y=u.*cos(u).*cos(v);
z=-u.*sin(v) .-  sin(60/180 * pi)*(sqrt((x).^2 + (y).^2));
figure(1)
mesh(x,y,z);
view([-57,32])
h=gca; 
get(h,'FontSize') 
set(h,'FontSize',14)
xlabel('X','fontSize',14);
ylabel('Y','fontSize',14);
zlabel('Z','fontsize',14);
title('3D Parametric Equation Lily impeller','fontsize',14)
fh = figure(1);
set(fh, 'color', 'white'); 

Image it creates:

What I'm trying to model.

How can I change the equation to have the sides be pushed up more and to the right at a steeper angle like the Lily Impeller image? The Left image is what I have the right Image is what I'm trying to get to.

Note: I know the Z value is what changes this I'm just not sure what the correct values should be to change it to increase that "steepness angle".