The Model Barn - Slider

They are definitely electric.
This is one of the things I have noticed when buying RC stuff, there is a pronounced lack of information & standardisation & its not until you get stuff in hand that you see the full story. The experienced will know what's what but the newcomer has to find out the hard way.
The difference in the boss sizes can be seen from this photo, if the 9" prop was put onto the 7" driver I don't think it would last long.
The X-mounts for the T2830 motors have different fixing centres from the A2212s for fixing back to the bulkhead. This isn't easily found when ordering.
 
 

But there is always different inserts that come with the props that fit in the hole to fit different shafts, 

Yes. And APC probably claim that each prop comes with full instructions.
 
Each prop comes with two slips of paper.
This photo shows each side of the two slips. The upper pair relate to not using an insert at all.
The left lower is for inch dimension shafts. The pair of inserts below it are for these shafts.
The right lower is for 3mm, 5mm & 6mm shafts. The three inserts below it are for these metric shafts.

This took me much mental anguish to work out.

 

 

Both the A2212 & T2830 drivers have 5mm shafts so with the appropriate inserts either prop can be fitted to either motor.


9 inch prop on A2212 driver


7 inch prop on T2830 driver
   

I wouldn't be happy with either of these pairings..

 

The data sheet for the T2830 says a 20A ESC , a Power of 210W & prop size 9x6 to 10x6.
My results say a current of 23A for a 9x6 prop which wouldn't suit a 20A ESC - or would the calibration routine turn down the juice abit?
 
The disclaimer means don't trust these figures.

While we're here the drawing shows a pitch diameter of 34mm for the X-mount which matches the actual beast.
The A2212 X-mounts I have from 4-max & Ebay measure 33mm.
Neither gives a figure but searching the internet shows up several drawings showing 34mm, with one at 32.5mm.

 

Reply to Qorneng's post on how much bang for your buck:
In the test I took readings at 25% intervals so this shows where the optimum efficiency will be depending on what thrust you need to stay in the air.
 
 

My phrase
"which wouldn't suit a 20A ESC"
is a diplomatic phrase meaning it would go bang.
The ESCs I am using are rated at 30A.

The centreing ring cannot be seen on the bottom photo, it is inside the prop boss on the opposite/backside of the prop against the driver face. The boss face at the front against the driving nut is un unmachined face of the prop.
That photo is meant to illustrate why I wouldn't put the 7inch props on the T2830 motor.

I can see why you suggest that, throttling back would give a better efficiency than the smaller prop.
If I set the high end point down to say 75% I would get 700g thrust for only 15A which should be enough to lift a 1100g plane & keep it in the air assuming the drag isn't too high
When I ran it at the full whack for a few seconds neither the ESC or the motor seemed to get too hot. The problem is the specs are not clear or even non-existing and the outsides may be getting cooled whereas the insides where the heat is generated are not & there are no sensors to tell you.
The balsa nosepiece was knocked off so I could put the lead straight onto the former which would expose more of the motor.
There was no provision for ventilating the inside of the model in the kit, I added two louvres but I don't know how effective they are.

Over the weekend I have been using my Raspberry Pi to drive the motor on my test rig.
Again there is a complete lack of information on calibration. I have been able to work out what I need to program to sequence the ESC through a calibration & get it to turn the motor so I can repeat the tests.
Needless to say I have not been using a prop while I was playing around.

I ran the T2830/09 motor with an APC 9x6 prop this afternoon driving it from my Raspberry Pi.
I calibrated the ESC from 30 degrees to 180 degrees and programmed it in steps from 50 degrees. At 100 degrees I was starting to get nervous so pulled it back to check the battery. It was warm but not hot so I took it up to 150 degrees when I decided that was enough.
The supply voltage had dropped to 10.5v but after switching off the battery recovered to 11.45v.
To me 900g thrust in a 1100g plane is almost vertical take off so my conclusion is that I will set the high end point on the throttle to 75% which gives about 700g thrust & I can always increase it later when I get through the training & can fly it myself.