The stock blower does work for many, not everyone. I have people coming to me telling my they wasted money on a RD3 because it can't run their larger pit. My design opens up a lot more variety in fan selection. You are also mistaken when you think that the fan is the only cost of running a damper. In comparison to the RD3, the current scale of the MicroDamper would cut the cost by well over HALF for someone looking to have it printed on a 3D Hub. That alone is enough for applause - not to mention it actually works. Can you send me a link to what I'm supposedly ripping off of yours? Why couldn't you make yours work? Mine seems to be doing well. I recall seeing Bryan try out a 80mm fan but couldn't make it work. But this is no surprise since 80mm fans can't produce enough static pressure, the 40mm fans on the other hand can and do. My comment about running the MicroDamper on full open was to decrease the required static pressure. I've already found fans that work just fine as-is, but running it full open won't require a fan that can produce as much pressure thus reducing costs further. So do not call my design or the use of a fan "ineffective" because you are talking out of your *** and read what I typed incorrectly. I'm actually a super nice guy, but I don't take too kindly on backhanded comments when I am trying (and succeeding) to better this project on my own dime.
People who have been members of this forum for more than a month or two know the damper I am referring to. Its posted in the RD thread about a year ago. I didn't pursue it because as Tom properly pointed out, the double sided valve reduces the resolution of the valve by half. In testing I found it to be a much less effective valve so I dropped it and moved on to more promising territory. Not only is the resolution cut in half, but the smallest opening it can create is two long rectangles which makes a fairly large opening to start. You get hung up on linearity but the fact is the more you close off a damper the more the rest of the grill leaks, therefore some non-linearity in the first couple % open is actually more linear in air delivery to the pit. But what do I know, right, I've only been experimenting with this stuff for over a year maybe 2 now....
On the size you are also mistaken. Do I need to take a pic of the RD3 next to a can of coors to prove its pretty damn close to the size of your damper? Not to mention you have not integrated any connectors and keep talking about needing a larger fan, by the time you have a complete design with a fan that can push air like it needs to guess what, it's gonna be about the same size damper and cost about as much to get printed anywhere.
As for running a big pit, I guess you overlooked the post made by the guy running the commercial Stumps smoker with the RD3, he gets outstanding results as do others running UDS, offset smokers, bullet smokers, kamados etc. All tested many times over, in winter and summer weather, rain and snow... Like John B and others have told you, wait for winter and report back about how well the fan holds temps in the UDS. John B, like myself, has done enough real world experiments with this stuff to have a pretty good idea what the air flow requirements are and what can deliver it. I'VE actually never got a complaint about a RD3 and if I did I would make it good one way or another. So have your people that are upset with the RD3 they got from ME contact me please. Now if they printed the parts themselves and it didn't work well I have to wash my hands of it. The stuff I print works!
As for running a variety of fans, the original RD can run a BLOWER from the stock HM blower to as large as 25CFM, while the RD3 runs the smallest blower available that has the air flow to control the majority of pits out there. Why do you think Bryan selected a blower in the first place, or the BBQ Guru, Auber, ANYONE who makes a BBQ controller? Why do they all use a blower with pretty close to the same specs? Don't you think these people all did their research with blowers and fans? If you read what I said properly I said a fan in a tube makes a poor blower. That is a comment about the physics of air movement, not a comment on "your design". If you unplug your fan and put the damper on your Akorn I think you will find the fan spins on its own without any power, you might think it was doing something.... But it's the natural convection of the Akorn drawing air through the damper making the fan spin, your damper will likely work pretty close to the same with the blower on or off.
Apparently you are a super nice guy that likes to build off other peoples work and not give them credit, and instead gives them a hard time, and thinks he deserves applause for it. I can see why you would avoid referencing my dampers, it's tough to do without giving me credit for the basis of the design, and it seems you are all about getting applause and taking credit for stuff. Giving credit where credit is due, not so much....