Big Buck questions

[fstringham7a]

Hi to all

Will folks it is now time to bite the $$$$$$$$$ bullet and buy the the big ticket items. Engine/Instruments/Prop. Pretty much made the decision on everything but the prop. After discussing the prop purchase choice with a very knowledgeable plane builder/engine builder/all around great pilot the choices have been narrowed to the 72" 200 horse hartzell blended air foil or the 200rv whirlwind 72 inch two blade prop. My mentor is very high on the 200rv!

With that said, what are the views of the group, especially those of you that are flying behind a whirlwind prop.

200rv light but expensive...and gets about 5 plus mph more speed than the Hartzell.....based on one eye witness account that has flown behind both props. TBO @ 500 hours @ a cost of around $500. No problems with engine harmonic issues at various rpm positions.

Hartzell heavy but less expensive by $1700. TBO at 2000 hours at a cost of $2000. Engine harmonic warnings at various RPM.

So what say you? Decision will be made by Friday....I want to be done and flying asap!


Frank @ sgu RV7A "NDY"

[fstringham7a]

Hi Again

116 hits and no comment! What to do? If I am reading this correctly or not reading any comments it really doesn't matter either way according to you folks. One prop will be as good as the other! Weight/$$$$$/supposed performance of the 200rv as compared to the hartzell. Flip a coin is maybe the way I should make this decision.

Thanks for the help in this matter. No Really.....I mean thanks for the help, as I believe that no comment sometimes can read as long as a novel.

Frank @ SGU RV7A "NDY"

[kevinsky18]

There's a whole section on this forum dedicated to props. I'm sure you will find your answers there.

[rvbuilder2002]

Originally Posted by fstringham7a

Hi to all


No problems with engine harmonic issues at various rpm positions.


Frank @ sgu RV7A "NDY"

I can't comment on your other questions, but I am wondering about the above statement. Have they done testing to verify this?

My understanding was that they have not.

It is a common misconception that since it is not a metal blade that there is no reason to be concerned about it, but from talking to the Hartzel test engineers (they have there own composite propellers) this is totally untrue.

Even MT specifies limitations on some engine/prop combinations.

[hecilopter]

I think George posted an image of it in the other thread. IIRC, the Hartzell blended airfoil was the faster of the 2 props, in fact it was the fastest period. (except for some theoretical calculation they did on a FP Sensensich at 2730 rpm or something like that).

I think this is the image

http://img82.imageshack.us/my.php?im...op200415me.jpg

[fstringham7a]

Kevin

I did read the threads from the past ...was just looking for some up to date info and to be honest was also looking for someone to verify my understanding of the differences between the two props. Thanks for you help I appreciate the heads up anyway.

Scott it is true that I did get some info from Whrilwind on the harmonics issue but they seemed to down play it as not as big a factor as with the metal props.

So back to my question......What should I buy........I guess I am looking for someone to act as a parent ...or better yet a spouse to blame if the decision made goes south in the future?

Thanks for the help.

Frank @ SGU RV7A "NDY"

[hydroguy2]

Originally Posted by fstringham7a

....... Flip a coin is maybe the way I should make this decision.
......Frank @ SGU RV7A "NDY"

occasionally, there is more than 2 choices, SO I prefer:

Hanging all choices on the dartboard, install blindfold and fire away.

[Ironflight]

Originally Posted by fstringham7a

116 hits and no comment! What to do?

Yeah, but are those 116 hits from people who have flown both of your finalists? Many of us (or at least myself) have experience with only one of the props, so a comparison based on personal experience is impossible. Why then, did I choose my Hartzell? I read every thread that I could find (both here and on the old Yahoo groups), as well as reading some really great articles on Randy Lervold's site and an issue of the RVator that did direct prop comparisons. For my -8, the answer for me came out the BA Hartzell. Don't know if you'll come up with the same answer for a -7, but there are a tons of opinions already captured in the archives....

If there was a clear "winner", there wouldn't be several props to choose from!

[frankh]

Frank 1 here,

As you will remember I have the blended airforil 72 HartzHell prop...I also have it hanging out on a 2.25 inch prop extension.

From this you can deduce there are no W&B issues with the heavy prop even on an exension.

When I bought mine it was a slam dunk, Van's had done speed testing and found the Hartz to be the fastest, its definatly the cheapest and has the longets TBO (I actually thought it was longer than 2000 hours but oh well)

So for me the choice was obvious...even if the Whirlwind was 5 mph faster, the lower cost and much longer TBO would still make this an easy choice for me.

With the paralell motors (never could spell that word) there will be harmonic issues, I believe its only the counterweighted crank engines that you can run them where you like. To be honest my "avoid 2350RPM or less above 22"mp" limit is not an issue in the real world.

Frank 1

[robertahegy]

If you are going Hartzell BA on a 7A you should do a 74" prop.

Roberta