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Teaser Picture!

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ErichKeane

Well Known Member
Hopefully all will go well, and 331RV will be leaving for Oshkosh Friday! We're finally finishing up repair and paperwork after our accident a little while ago.

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Great to see the bird about ready for air under its wings again. I like that sexy three blade prop. That is what mine will have.
 
Prop

Just curious as to why you changed the prop from the standard two-bladed Sensenich?
 
I too love the three bladed prop. Not sure if it is an improvement to performance or not, but sure looks cool.
 
rgmwa said:
Just curious as to why you changed the prop from the standard two-bladed Sensenich?
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I unfortunately won't be at Oshkosh, but 2 of the partners are flying it out (fingers crossed!). Also note that we had Sensenich change the color scheme to black/red instead of black/white.

We've decided to change to a 3 blade for a few reasons:
1- We had the opportunity!
2- Cost was pretty low (only $500 difference when replacing the whole thing)
3- We like the look of a 3 blade better than 2
4- 3 Blade is actually 1lb lighter than the 2 blade
5- We've been promised that the performance figures are identical, or nearly so. (Sensenich says same cruise, better climb/takeoff, reduced noise)
6- The pitch-setting is a ton easier and much more accurate
7- It ought to run smoother and sound better

Really, it was an option we discovered when we called up Sensenich. They said that 1 builder had already ordered one in Florida, so they knew how to drill for the pitot tube already, and already had the proper spacers.

Besides that, the only additional work was rebuilding the spinner (the front bulkhead is actually already drilled for the new bolt pattern!), and tracking down long enough bolts! Sensenich sent us 2 sets of bolts, each were too short. Luckily our on-field A&P had a handful of AN5-50 that were just right (actually-48 or -49 would be better, but beggers cant be choosers :)).

We'll probably have to modify the cutout for the exhaust in the cowling since the 3 blade makes it tougher to install the cowling, but otherwise it should be pretty easy! The only hard part will be the paperwork through the FAA I think :)
 
ErichKeane said:
The only hard part will be the paperwork through the FAA I think :)
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Having experienced a switch from 2 blades to 3 blades prop on my trainer (Allegro 2000) I am a converted to three blades, just for the sake of smoothness. The easier blades adjustment and cool look just add to the appeal. It would be interesting to have VANs opinion on the matter. Did you discuss this with them before making the switch?
 
WingedFrog said:
Having experienced a switch from 2 blades to 3 blades prop on my trainer (Allegro 2000) I am a converted to three blades, just for the sake of smoothness. The easier blades adjustment and cool look just add to the appeal. It would be interesting to have VANs opinion on the matter. Did you discuss this with them before making the switch?
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I discussed it with Dick before hand, and he was going to get back to us though he never did.

I did receive info afterwards (recently) from the factory that said they DID try it at one point, but were unable to get the same cruise speeds with the 3 blade. We'll see, as we are hoping to fly either tonight or tomorrow, and we can let you know. We'll get tons of cruise experience since it is going from OR to Oshkosh just after.

What paperwork did you file with the FAA? I'm thinking just the 8730-1, right?
 
Three blade prop

I'm sure that I'd like one too. Hope that your performance figures are good and that Van's will be interested and will offer a three blade option eventually. In my opinion, the 'cool factor' might even sell a few more RV-12 kits if a three blade option was offered from Van's. I am interested to know how much the three blade prop/spinner combination costs if you can divulge the answer. Thanks for the nice post!:cool:
 
E. D. Eliot said:
I'm sure that I'd like one too. Hope that your performance figures are good and that Van's will be interested and will offer a three blade option eventually. In my opinion, the 'cool factor' might even sell a few more RV-12 kits if a three blade option was offered from Van's. I am interested to know how much the three blade prop/spinner combination costs if you can divulge the answer. Thanks for the nice post!:cool:
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The spinner stuff was all from Vans' kit, we just needed to replace the rear-plate, fiberglass, and pitot bushing. In a new kit, this would cost nothing :)

The 3 blade prop from sensenich was 2100 or so I think (perhaps off a few hundred?), and they gave us a $400 credit for turning in our old 2 blade hub. No extra cost for the different blade colors either!

We'll hopefully be flying soon, so we'll let you know about the performance. I was told today that we ought not expect as good climb if set for the same cruise, or vice versa, but I'm hoping we'll do alright.
 
Hi Tony, thanks for the reminder! I don't know what pictures I have of it since, but I'll have to look around. Two of our members made it to SD, but weather prevented them from making it to Oshkosh. We ended up getting the plane in the air just in time too!

Performance wise, the 3 blade prob is comparable to the 2 blade. The pin system is about 100x better than the delrin center cap for aligning the blades. We have it on about the middle setting. It is currently at setting 3 of 6 (IIRC), and we have no problem making it to 120 kt, and climb is at about 900 fpm at close to 1320. We could bias for climb a little more if we wanted to, but we've been happy enough so far. The guys (definitely right AT max gross!) never complained going through the mountains.

Additionally, burping the oil is a little easier, since there is always a blade close enough to grab. Towing is a little more difficult with the tow bar, but we've got a decent system as long as you are careful. Pulling the cowling is a little more difficult, but by enlarging the exhaust hole, it has become not a problem as well.

I definitely prefer the 3 blade prop, and I love the color that we picked (black/red). I will note that install was actually not much harder than the 2 blade, other than having to cut the spinner without the template or markings. I think we did a pretty good job all told on that anyway!
 
The "word on the street" says that a three blade will be smoother and take off quicker, but will suffer a small loss of top speed compared with the two blade. For me the smoothness is worth the change.
 
DonFromTX said:
The "word on the street" says that a three blade will be smoother and take off quicker, but will suffer a small loss of top speed compared with the two blade. For me the smoothness is worth the change.
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The 3 blade is fully adjustable, like the stock 2 blade. It has 6 positions for adjustment, which we found ranged from 'very fast climb' to 'very efficient cruise'. I think you'd be able to find one that matched what you expect out of the RV-12. The different 'tamer' sound of the blades through the air was definitely a welcomed change though.
 
Which prop?

Erich,
The Sensenich website doesn't seem to list a three bladed prop. Which model is it? I like the look of the prop, and if it's easier to adjust than the two bladed version, quieter and with the same performance, I'd seriously consider it. Has anybody else installed one yet?
 
The part # is 3B0R68C-0. It is easier to adjust the pitch, but would be near impossible to do on the plane. What we do is lay the hub on the floor, set all of the blades and tighten it down, then bolt it to the hub. If you're careful, you can do this alone, but I'd suggest 2 people.

I don't know why it isn't on the website, but if you called I'm sure they would still be able to get you one.
 
I agree the 3 blade looks better, not sure why, but it does. The negatives mentioned tho seem to me that the two blade is a better choice. This opinon primarily based on the fact the 3 blade requires adjustment off the plane. Knowing how many times adjustments may be required to find the right (best for me) pitch sounds like a big hurdle. The cowl removal is an issue as well. Cruise speed impact unknown. Then there is the additional cost. The 3 blade is very cool. Just not my choice considering the attendant issues.
Dick Seiders
 
Some three blade props do not have to be removed to adjust pitch, the Warp drive for instance I am using don't. Looks are nice, but smoothness is hard to put a price tag on, long term effects of a two blade on the gearbox may not be fully known yet either.
 
DonFromTX said:
long term effects of a two blade on the gearbox may not be fully known yet either.
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I am pretty sure that when the Katana was introduced in the late 80's, it had a 2 blade prop. Many, many thousands of 912's have been flying since then in Europe and the U.S. with two blade props.
I think that provides enough evidence that you don't need to worry about the gear box dependant on how many blades your prop has.

Incidentally... The parent company Rotax, got its start designing and manufacturing gear boxes for machinery and other equipment.
 
Van's option?

I may be dreaming here but I would like to purchase a three blade prop from Van's as part of the kit. How about it, Van's?
 
Is the prop currently supplied with the engine that is ordered from Van's? Is that included in the $28K powerplant kit? I'm guessing it is, since the order page says everything is included except for fluids and paint.
Thanks,
 
For E-LSA kits, everything must be supplied. To qualify as an experimental light-sport aircraft under 21.191(i)(2) the kit manufacturer must issue a certificate of compliance, 8130-15, covering all kit components and the aircraft must be built in strict accordance with the kit plans and instructions.
The kit manufacturer cannot issue the 8130-15 unless he has supplied all components.
 
E. D. Eliot said:
I may be dreaming here but I would like to purchase a three blade prop from Van's as part of the kit. How about it, Van's?
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After developing a spinner installation, and then installing the 3 blade propeller that Sensenich provide, on to N412RV, the decision was made not to offer it.
Testing showed that it would induce enough of a performance compromise, that a new POH would have had to be produced (I am not talking about just a couple Kts, or a few FPM in climb).

I know Erich claims they are getting equal or better performance with their 3 blade.

The only explanations I see possible are that he/they haven't done an equivalent level of detailed testing, or they have a different propeller than Sensenich supplied for evaluation.
 
Would you give us some generalizations of the differences?

rvbuilder2002 said:
After developing a spinner installation, and then installing the 3 blade propeller that Sensenich provide, on to N412RV, the decision was made not to offer it.
Testing showed that it would induce enough of a performance compromise, that a new POH would have had to be produced (I am not talking about just a couple Kts, or a few FPM in climb).

I know Erich claims they are getting equal or better performance with their 3 blade.

The only explanations I see possible are that he/they haven't done an equivalent level of detailed testing, or they have a different propeller than Sensenich supplied for evaluation.
Click to expand...
 
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