Radishes are one of the easiest vegetables to grow, only that they are grown in season. They are considered a cool season crop. That means early Spring or early Fall. They struggle in the heat of summer and the aphids devour them real fast.

That's surprising!
They wouldn't like shallow soil because of the longish taproot. Is it that you're getting plenty of leaf but the radishes aren't filling out? If so maybe more watering would help. Maybe they just need more time, it's easy to poke the soil to see when they're an ideal size for pulling

The main reason is that they run to seed before the root swells.plenty of water and root depth. I think they are my Jinx crop.

OK it's the summer heat causing them to do that. It's simply too hot for radishes. It's not their season. They are bolting. Save yourself frustration. Try radishes again in late August. For now try something else. Tomatoes, Cucumbers, Aubergine, Onions, Peppers, Summer Squash are good choices. You may have to get starter plants at the nursery, because we are well into the season now.

The secret of radishes is, just sow a few at a time so you get a succession of the crop. Obviously, the lack of water will also cause them to run to seed. If you have only a shallow seed bed, then grow a variety like Cherry Belle. The only real pest is Flea Beetle which will perforate the leaf edges.

I don't grow them but this is the rHS advice.

https://www.rhs.org.uk/advice/grow-your-own/vegetables/radishes

A facetious suggestion - if they are easy for kids get the kids to grow them...(sorry, lol) I only tried once but I couldn't grow them either...

I like your thinking steragram, I'll use the child that untangles my t v.

My first two tries--as a child :)--had the same problem. The first was the wrong season, and the second was too little water.