Rocket Mass heater

I did a forum search for "Rocket Mass Heater" and found nothing.
Can this be? Could it be just some website problem?

In any case, if so, go ahead and point the way to me, but in the mean time, for those who are very familiar with the subject, I was wondering, at maximum, how long can the exiting vent tubing/flue/etc. can be before becoming ineffective due to the air from the heater cooling too much, thus reducing the air flow and either causing the heater system to not function in a necessary or preferred manner, or possibly even causing a hazard to due the air/fumes/smoke stalling or backing up, building up in the interior of a structure...

Thank you.
- Sorry, just saw the topic for this. I will copy this there....