Small rocket shop heater?

Is there a design for a small heater for an infrequently heated shop that uses rocket tech to be efficient?  

I'm imagining either a batch or J tube burner that feeds a barrel or bell.  But then there's no mass so the heat gets out into the room right away.  Yet enough heat comes out into the room that the exhaust is not wastefully hot.

Also it would be for a smallish space, between a 1 and 2 car garage in size.

Hi Mike,
What worked for me in my smallish shop was a 6" J tube which then switched over to a 6" batch box. I enjoyed both very much but can say I appreciated the longer burn time and viewing window (casserole lid) of the batch a wee bit more.
Of more significant importance though was the fact that it was 2 barrels high which allowed much more instant heat into the shop when it was really needed.
A small 5' x 1.5' stratification bench tucked under some wall shelving also helped to hold a bit of heat for later. Average chimney temps were around 170F

Thanks Gerry!  So were they standard 55 gallon barrels?  How much space do you have between the top of the barrel and the ceiling?  My shop has a really low ceiling (6'8" or so).  I also can't handle much weight since it's not the ground floor...

Yes, 55 gallon barrels that fit perfectly one into the other friction fit with rope gasket to seal the joint.
My shop had a 12' ceiling so there was little concern for the roof getting too hot. I put a heat shield above just in case.
So since your limited vertically, then perhaps you could place a second barrel (or other metal container)
next to your stove and use it as a quick heat releasing stratification chamber.
The Batch rocket 'thingy Peter and Matt built at the labs comes to mind. I think at some point it was filled with firebrick to hold a bit of heat too.

Ok, so after the heat leaves the first barrel, it can just go into enough other barrels (lower down) to bleed off the remaining heat before going up the chimney.  Without mass...  Kinda like the big auditorium heater at WL only without the long bench?

Exactly Mike. Not sure how much of a footprint you'll have to work with but is an option.
Putting more or less bricks into the second barrel could be used to regulate how much heat will be instant and how much will be for later. Of course this will also dictate how much heat goes up the chimney. 150- 200F is a good ballpark place to aim for and still have a reliable draft.

I have a decent footprint to work with but, of course, the less space it takes up the better.  Thanks Gerry, I'll think on it some more...