Increasing the DF

[gouldilocks]

When you have the wire mesh off you do get a higher df - when it gets to 255 it resets to 0, so a reading of 66 on damper 10 with the mesh off is in fact 255 + 66 = 321.
I have left off the mesh for years now and I get a df of 200 on damper level 5/6 - The highest df I have recorded is 369 (255 + 114) on a particularly cold morning.

( This is at sea-level - I imagine it would be 15-20% lower at somewhere like JHB or Denver)

Paul G

[lindsayh]

When you have the wire mesh off you do get a higher df - when it gets to 255 it resets to 0, so a reading of 66 on damper 10 with the mesh off is in fact 255 + 66 = 321.
I have left off the mesh for years now and I get a df of 200 on damper level 5/6 - The highest df I have recorded is 369 (255 + 114) on a particularly cold morning.
( This is at sa-level - I imagine it would be 15-20% lower at somewhere like JHB or Denver)
Paul G

Hi Paul - thanks for lurking - I mentioned your high DF exploits earlier in this thread

[gouldilocks]

When you have the wire mesh off you do get a higher df - when it gets to 255 it resets to 0, so a reading of 66 on damper 10 with the mesh off is in fact 255 + 66 = 321.
I have left off the mesh for years now and I get a df of 200 on damper level 5/6 - The highest df I have recorded is 369 (255 + 114) on a particularly cold morning.
( This is at sa-level - I imagine it would be 15-20% lower at somewhere like JHB or Denver)
Paul G

Hi Paul - thanks for lurking - I mentioned your high DF exploits earlier in this thread

Tim,
I hadn't read your opening post thoroughly - the numbers I recorded are on a PM3, not a PM4, so not sure if the same applies.

Lindsay,
I used to do all my training on df 300 - 350, and PB/CTC attempts on 220/225.
Not done any marathons on max df - it's too hard on the upper body, however I did an FM on df 300 and that was very comfortable, getting below 3hrs quite easily(quick for me!!)

[Tim K.]

Hi Paul,

Thanks for your post. The pm4 seems to have similar parameters as the pm3. I didnt go past the top end as I was doing my test but it certainly does "wrap around" at some point. With the PM3 does the displayed DF effect the 500m time and the wattage (when it wraps around does the time go up wattage go down)? ie your actually 256, display is 1, 500m time is forever and wattage is very low.

Thanks again!

[gouldilocks]

Hi Paul,

Thanks for your post. The pm4 seems to have similar parameters as the pm3. I didnt go past the top end as I was doing my test but it certainly does "wrap around" at some point. With the PM3 does the displayed DF effect the 500m time and the wattage (when it wraps around does the time go up wattage go down)? ie your actually 256, display is 1, 500m time is forever and wattage is very low.

Thanks again!

No problem Tim - when the monitor does the wrap-around, the 500m time records as normal, so a 2:00/500m pace at df 20(275) gives exactly the same perceived effort as a 2:00/500m on df 140 - tbh I have not checked the wattage readings, will give that a try later, but I suspect that reads normally too as it is just an equivalent representation of your 500m pace.

Paul G

[Carl Watts]

Had the flywheel off for some routine maintenance so decided to do some testing.

No side cover or grille and I got 242 with a clean fan, pulling hard enough and I also suddenly saw 20.

This was also easier to pull then the housing assembled correctly and the damper set to 10.

Fully assembled the DF on my machine varied from 80 to 215.

So whats going on ? its easier to pull with the no covers than it is assembled and the damper on 10 and yet the DF on the screen can be higher ?

My explanation is and someone from C2 should chime in is that the DF calculation is clearly calculated by the acceleration, rpms and deceleration of the fan. Removing the covers seriously affects the airflow and your able to accelerate the fan easier and reach a higher rpm but possibly the deceleration is not affected and the result is a high DF calculation. Possibly with no side cover there is a serious amount of blade slippage as the air comes out in an axial rather than radial direction.

This could be simulated by having a second person on damper control, when you pull on the drive they set it to 5 and at the end of the drive they wack it to 10. Just have someone do this for your 500M row and your going to get an outstanding time. This is one of the reasons your NOT allowed to touch the damper after you start rowing.

In effect your are NOT able to remove the grey side cover and get a legitimate verified time. This would really only apply to the 100M, 1 minute and 500M as I would hate to row anything longer on what still felt like a pretty high DF.

I didn't remove the stainless grille only, I suspect it would be fine to do this. You can for example fit the "C-Breeze" to the housing and this does affect the DF but doesn't stuff the DF calculation and the same way the grille can get slowly blocked until the DF is 90 with the damper set on 10. With the grille ONLY removed I suspect you would get a very high DF approach a legitimate 240.

Obviously not advisable if you have little kids running about because if they put their hands in there while your rowing.....

[jackarabit]

Volute (shroud halves) in place = air pump. Volute removed = air agitator.

[Carl Watts]

Volute (shroud halves) in place = air pump. Volute removed = air agitator.

Yes clearly without the side cover is producing turbulence and other airflow anomalies that are not surprising outside the Concept 2 design spec.

You have to run the side cover that incorporates the damper on the Erg or else the monitor results will be wrong.

[gouldilocks]

Had the flywheel off for some routine maintenance so decided to do some testing.

No side cover or grille and I got 242 with a clean fan, pulling hard enough and I also suddenly saw 20.

This was also easier to pull then the housing assembled correctly and the damper set to 10.

Fully assembled the DF on my machine varied from 80 to 215.

So whats going on ? its easier to pull with the no covers than it is assembled and the damper on 10 and yet the DF on the screen can be higher ?

My explanation is and someone from C2 should chime in is that the DF calculation is clearly calculated by the acceleration, rpms and deceleration of the fan. Removing the covers seriously affects the airflow and your able to accelerate the fan easier and reach a higher rpm but possibly the deceleration is not affected and the result is a high DF calculation. Possibly with no side cover there is a serious amount of blade slippage as the air comes out in an axial rather than radial direction.

This could be simulated by having a second person on damper control, when you pull on the drive they set it to 5 and at the end of the drive they wack it to 10. Just have someone do this for your 500M row and your going to get an outstanding time. This is one of the reasons your NOT allowed to touch the damper after you start rowing.

In effect your are NOT able to remove the grey side cover and get a legitimate verified time. This would really only apply to the 100M, 1 minute and 500M as I would hate to row anything longer on what still felt like a pretty high DF.

I didn't remove the stainless grille only, I suspect it would be fine to do this. You can for example fit the "C-Breeze" to the housing and this does affect the DF but doesn't stuff the DF calculation and the same way the grille can get slowly blocked until the DF is 90 with the damper set on 10. With the grille ONLY removed I suspect you would get a very high DF approach a legitimate 240.

Obviously not advisable if you have little kids running about because if they put their hands in there while your rowing.....

I have tried rowing without the side cover and it felt easier than with the standard set-up - I get the higher df and perceived effort from having the metal grille off and the side cover on - wit the side cover off it seems like the air pressure around the blades is lower - I'm no scientist but that's how I saw it.
I would be very surprised if record attempts were allowed without the metal grille on, although for the sprints you would have to be immensely powerful to get the wheel up to speed quickly enough to be effective.

Paul G

[Carl Watts]

Probably not on the 100m, thats a trade off between using a low DF to get the flywheel moving and then effectively not having a high enough DF to really start putting in the power but the 500M is different, your pretty much forced to choose a higher DF from the start.

A big enough Guy would be able to handle the grille removed and as long as the DF comes up lower than 242 or there abouts and doesn't start throwing random DF numbers, its going to be a legit verified row. You may not be allowed to do this at a race event but I would certainly allow it as a verified row. As long as it falls inside the Concept 2 DF calculation in the monitor, then its not a problem.

[Tim K.]

Volute (shroud halves) in place = air pump. Volute removed = air agitator.

Yes clearly without the side cover is producing turbulence and other airflow anomalies that are not surprising outside the Concept 2 design spec.

You have to run the side cover that incorporates the damper on the Erg or else the monitor results will be wrong.

Simply put, none of the above is correct.

A volute is not a simple shroud. A volute is the "snail shell" on a centrifugal fan or pump used to gather the fluid being moved and direct in one direction: https://www.google.ca/search?q=volute&r ... olute+pump

It may be clear to some that not having side covers causes turbulence but that is the difference between "common sense" and education/"good sense".

No volute/side cover/shroud:

http://www.ebmpapst.com.au/en/news/late ... l_7808.php

https://www.google.ca/search?q=plenum+f ... 2VfG5MM%3A

Edit: The picture in the first link I posted didnt appear as expected.

[jackarabit]

Volute (shroud halves) in place = air pump. Volute removed = air agitator.

Yes clearly without the side cover is producing turbulence and other airflow anomalies that are not surprising outside the Concept 2 design spec.

You have to run the side cover that incorporates the damper on the Erg or else the monitor results will be wrong.

Simply put, none of the above is correct.

A volute is not a simple shroud. A volute is the "snail shell" on a centrifugal fan or pump used to gather the fluid being moved and direct in one direction: https://www.google.ca/search?q=volute&r ... olute+pump

It may be clear to some that not having side covers causes turbulence but that is the difference between "common sense" and education/"good sense".

No volute/side cover/shroud:

http://www.ebmpapst.com.au/en/news/late ... l_7808.php

https://www.google.ca/search?q=plenum+f ... 2VfG5MM%3A

Edit: The picture in the first link I posted didnt appear as expected.

Might this be a home-brewed volute, Sparky? I think it is in that it redirects air exhausted thru the perfmetal band onto sweaty lil ol me.

[Tim K.]

By definition it isnt a volute as a volute is spiral/scroll in shape but that doesn't stop it from being awesome! Gonna ignore the "Sparky" cause Im not sure how your using it.

I now have a project for this afternoon, Thanks!

[jackarabit]

Tim, have a look: http://www.c2forum.com/viewtopic.php?f= ... ow#p293471

[Tim K.]

Thats great! I had originally wondered why C2 hadnt made a housing with a directional discharge so you could point it toward or away from yourself, then I plugged in a fan and forgot about it. Thats a cheap, simple way to get cooling airflow proportional to workload.