I felt it was worth a little summary on my experience swapping out my Sensenich aluminum FP prop for a new WW GA200, ground adjustable prop. I am still tweeking the pitch, however let me provide some initial information. One big impotus for me to change out the prop was to take advantage of the HP available to me beyond 2600 RPM. As you may know the Sensenich (79" pitch) has an RPM limitation of 2600 RPM, while my engine Redline is 2700. On my first 12 hours of Phase 1, I found myself at or near my 2600 limit on several occassions.
Some background first:
Aircraft: RV-9A (in Phase 1 and fully faired)
Engine: TMX IO-320 w/ High compression cyl producing 165HP @ 2700
Empty CG: w/ Sensenich prop - 78.16"; w/ WW 200GA - 78.68" (note that the GA 200 is 11lbs lighter, however my CG only moved aft by 0.52")
I do not have complete side by side comparisions (not my intention here). These are some numbers I observed after pitching the prop to 19.5deg.
Rate of climb: (solo, full fuel) - 2100-2300 fpm (sorry, I don't have the density altitude or OAT figures noted - I will try and get some later.)
Airspeed: appears to have increased by about 5-10knts (at 4,000'). Again I cannot duplicate identical conditions I had when the Sensenich was installed however being that I can spin the 200GA up a bit more, I am able obtain faster speeds.
The prop runs very smooth - I will have it Dynamically balanced after the spinner is painted.
Installation was not without some issues, all easily surmountable/avoidable. The WW 200GA is comprised of the following components: 2 composite blades, billet alum hub assembly, composite backplate, 'front plate' and spinner, all mounting hardware. A 2.25" spacer is also required (sold separately). The WW 200GA arrived in beautiful condition - I had them paint it gray (I'll try and post some pictures very soon). I also purchased the WW spinner - also a very nice product - no trimming, just paint and screw on.
Please be sure to note some very important information below regarding mounting hardware. Although WW sells a 2.25" spacer, I elected to purchased a spacer from Saber (www.sabermfg.com
). It is beautifully machined with the added benefit that I can use it should I elect in the futureto pull this GA prop and install a constant speed prop.
Ok - here is where I had issues. WW Propellers provided AN hardware to mount the hub to the prop flange. My flange uses 7/16" bolts, so AN7's were provided. Installation of the hub using the supplied AN7 bolts resulting in 4 severely galled prop flange bushings. Two of the bolts went in smooth and fine, 4 bolts were challenging. When I removed the bolts due to threading resistance I found bits of metal from the threads of the galled bushings. Apparently the supplied AN hardware does not have the tight tolerances that the previous Sensenich prop bolts exhibited. Well I was not to happy about the damage to the bushings. The other issue with the supplied hardware was the length and grip range. Both the length and grip were short in my opinion. I was not comfortable with the 1/4" thread engagement that resulted from the AN7 hardware. Due to the shoulder length, this is all that is possible using AN hardware.
My solution was another call to Saber. Sam uses Grade 9 bolts on all of his spacers and hub extentions. This hardware is not cheap, however given the alternative, I see no other solution if I want to be comfortable that the prop was going to stay where it is intended to stay
. Sam and I worked out the necessary bolt substitutes which gave me the needed grip length plus added thread engagement. IN ADDITION, Sam sells prop flange bushings. He supplied me with 6 new prop flange bushings to replace my galled ones. Unfortunately this also was not cheap, but I felt it was a truly necessary given the state of the damaged threads. With a little research on VAF I learned how to quickly remove and replace these bushings - no big deal in the end - just time and money
Once all new bushings were in place the installation went quickly and smoothly using the new bolts. The last challenge was to set the proper pitch of the blades. Clearly an indexed GA hub would be easier, however the WW hubs gives you the ability to make very minute pitch adjustments. A good digital protractor is essential. With a little finese, I was able to get the blades pitched to within 0.1 degree of each other (spec is 0.2deg). I started at 19.5 deg pitch. I found it much more accurate to set pitch while blades are leveled at the 9o'clock/3o'clock - pitch one blade, then rotate 180 deg, re-level and pitch the second blade.
After installing spinner I did a run-up - 2200 rpm static. I then took it up for a short flight - prop readily approached redline. I landed and repitched to 20deg. which resulted in a static of 2150 rpm. I have flown 4 hours at this pitch setting. Performance has been great all around - great climb and better cruise then with the Sensenich. I may want to pitch an additional .25-.50 deg at some point to give me better performance at cruise 8,000'-10,000'.
Overall I am pleased with the WW 200GA - both WW and Saber were easy to work with. I know my performance data is not totally complete, so don't beat me up for not having all of the tables of data!