How can I curve one edge of cube?

Hey Guys,
Fairly new to Blender and need a little help.
I am modelling a Star Trek Shuttle (yeah yeah I know lol) from a reference image, it looks fairly simple mainly box shaped with some tapered sides, but the front third has a small radius on the bottom coming up to a snub nose.

Is there a way to bring up the bottom of the cube into a nice sweeping curve?

I tried the Proportional Editing Tool
By extruding one face a few times - selecting the bottom front edge - G - Z but as I move the edge up the other edges follow in a straight line and I am after a curve.
How would I do this ?
Is there an add on or Modifier that can do this ?

Selecting an edge and using Ctrl B puts a chamfer not a rad.

thanks in advance

Selecting an edge and using Ctrl B puts a chamfer not a rad.
You can use the mouse scroll wheel or the options in the toolshelf or F6 to add additional segments to the bevel

Hey Richard,
Thanks for the reply, I didn’t know about rolling the mouse wheel to get radii, (its in the memory banks now)
But, its not quite what I was after (maybe when I learn more about Blender I will work it out)
What I am wanting is.
Start a new file - Edit mode- Select 1 face - Extrude about 1 1/2 times the length of the cube (so cube is 2 1/2 its original length) - select the bottom front edge.
Now what I am trying to achieve is to make a slow radii from just below the top edge to the edge that was the start of the extrude.

There is a tool in MODO which is similar to the Proportional Editing tool in Blender only (from what I can remember) you use a straight line and depending where the pivot point is it influences the part that you want to deform, maybe would be a nice addition in Blender)

PS: I think it was under the “Falloff” menu which gave you a few selections on how you want the falloff to work, and “Linear” was the one that would enable you to put a slow curve .

Please don’t make people have to guess what is in your mind. Your description could mean many things to many people.
Don’t be terrifies of showing what you mean

Hi Richard
In the image I am trying to create the radius marked.
the only way I can thing of is to extrude to the front of the craft, select the edge on the side and subdivide it a few times, then do the same on the back edge, use the knife tool to join the vertices across the bottom, then use the grab tool and move each edge up to match the image.
I thought there may have been a tool to do that in one or two mouse clicks.