Click image for full size image

Submitted by: Kendall Simpson

Whirlwind Aviation 400C-M14 on Pitts 12

The short story is that yes the Whirl Wind 400C-M14 is definitely a viable alternative to the MT!  The un-opinionated facts are this; they pull the same on the scale, the MT is 4lbs lighter and the Whirl Wind is $3,400.00 cheaper.

Now here's the long story...

I was hoping to have pictures of the pull test but the way it works I guess it's not possible.  As I was running the airplane at full power, Kevin would go behind it and look at the dial gauge on the giant "fish scale".  He told me that the needle vibrates about 100lbs so he just tried to average the middle of the needle blur.  We pulled my Whirl Wind first and got 1,650 lbs.  When I got done pulling the MT he said it was the same 1,650 lbs. average as the Whirl Wind had pulled a few minutes earlier.  Then he said it possibly was a bit more, but too hard to say.  It was a wash and they were the same.  In hind sight we should have video taped it so interested parties could see the blur and make their own interpretations.

After the pull test I made a short test flight with the MT on my airplane.  This was my first time flying a zero time MT.  It was much smoother than any other MT I've flown.  There was still wire buzz at most RPMs but not nearly as bad as the other ones I've flown.  It was still not quite as smooth as the Whirl Wind but nothing to complain about.  I could still find the smoothest sweet spots at full power, around 2,600 RPM and around 1,950 RPM just like the other MTs I've flown.  This works out good for most situations.  There are only a few RPM ranges where I get slight wire buzz with the Whirl Wind.  I have 90 hours on the Whirl Wind now and no hint of the vibration or balance issues I've felt with all five of the other MTs I've flown on M14s.

The MT vertical penetration, top speed and cruise speeds seemed exactly the same as what I'm used to seeing with the Whirl Wind.  Basically I am getting 2,300' of vertical and 192 MPH indicated flat out.  The only performance difference I could see or feel from my test flight was braking action.  When I pulled the power off on the MT it didn't slow quite as much as the Whirl Wind does.  This became very obvious on landing.  Don't get me wrong; there is a lot of brake effect, just not quite as much as the Whirl Wind.  I wish I would have had time to do more elaborate test flights with recorded data but my schedule wouldn't allow it.  I can guarantee there would be very little difference in performance numbers from what I did experience.

This particular MT didn't surge on me at all.  I've never had any surging with the Whirl Wind and I've flown it with two different stock governors.  I know it's pretty rare not to have surging at some point with the MTs with the stock governor, but I didn't experience it with this particular prop.  From what I understand MT has modified some stock governors and then developed a new governor altogether to help with the surging issues.

All up the MT is definitely lighter.  We weighed the entire assemblies; including the hardware, prop, spinner, back plates etc. as a whole unit.  The MT weighed 88 lbs while the Whirl Wind was 92 lbs.  We weighed just the spinner domes and found a 2 lb difference between the flexible Kevlar MT and the rigid Carbon Whirl Wind spinner.  I'm sure the steel flange adapter required on the Whirl Wind like on the other MTs was the difference.  I'm trying to get the weight of a single blade from Whirl Wind.  It would be great to compare single blade weight if we could get the MT blade weight as well.  I'm guessing the hollow carbon Whirl Wind blades would be lighter than the wood filled MT but I can't confirm that yet.  Lighter blades would mean less stress on the crank and less gyroscopic effect.

I guess the only other thing I can think of is Whirl Wind lists for $14,500.00 including the spinner and all hardware.  I recently saw a quote of $17.880.00 for an MT prop and spinner. I don't know what their new governor sells for.

Those are the facts as I know them. Let me know if you have any questions.