Prop Restrictions with Mag/Pmag

[Brantel]

I am soon going to be installing a Hartzell C2YR-1BF/F74972 and I contacted Les
@ Hartzell to talk about any restrictions that may apply to my setup.

I have a carbed 180hp O-360 with a Mag/Pmag. The Pmag is set to run on the B curve.

Les mentioned that the C2YR-1BF/F74972 does not have any restrictions on an 180hp O-360 with Mags and I got the default answer that they have not tested the prop with Pmags or other electronic ignitions that have timing advance and therefore he recommend that I follow the 200hp restrictions.

Here are the 200hp restrictions:
"Continuous operation is prohibited above 24? manifold pressure between 2350-2550 RPM."

My questions...

Does anyone have a similar setup and if so what if any restrictions do you limit your aircraft to?

Is the 200hp restriction above really an issue in normal use with an RV7?

Do you have any other comments regarding this topic that would be good to know/consider?

 

[Sig600]

Opted for the Whirlwind for this very reason.

The only question is 200RV or the new one?

 

[DanH]

Do you have any other comments regarding this topic that would be good to know/consider?

Les has measured stress data from formal vibration surveys to guide his opinion, so I'd take the recommendation seriously. The prohibited power settings don't seem like something you would really miss anyway.

Opted for the Whirlwind for this very reason.

Because you can describe the blade modes?

 

[Sig600]

Les has measured stress data from formal vibration surveys to guide his opinion, so I'd take the recommendation seriously. The prohibited power settings don't seem like something you would really miss anyway.



Because you can describe the blade modes?

Because of Hartzells operating restrictions that WW does not have, and the performance.

 

[PCHunt]

IINM, (if I'm not mistaken), the aluminum blades of the Hartzell are subject to harmonic vibration and the resultant fatigue, whereas the composite blades of the Whirlwind are not.

Correct me if I am wrong on this.

 

[rzbill]

IINM, (if I'm not mistaken), the aluminum blades of the Hartzell are subject to harmonic vibration and the resultant fatigue, whereas the composite blades of the Whirlwind are not.

Correct me if I am wrong on this.

Does anybody have any evidence that whirlwind has actually instrumented and tested their props as hartzell does? For me, the lack of this and the early hub problems took whirlwind off the list at the time I needed to make the choice. Lack of testing does not mean a product is automatically better.

 

[Captain_John]

Does anybody have any evidence that whirlwind has actually instrumented and tested their props as hartzell does? For me, the lack of this and the early hub problems took whirlwind off the list at the time I needed to make the choice. Lack of testing does not mean a product is automatically better.

Amen, Bill.

I didn't care for the WW hub problems that they had early on and the CG was better for the -7 with the weight up front... that is why I chose Hartzell.

Les is a great guy and he knows his product very well.

Brian, i will be in a similar situation as you, as I have the G3i electronic ignition. Now, i don't have any way of analyzing engine pulses and how it subsequently resonates through the blade, but I will have the ability to shut off the ei from the pilot seat. Though, I think that I would prefer to leave it on and respect the Hartzell admonition about power setting, as it really isn't hard to respect.

I wish Hartzell would run our setup through testing, as it is a common RV setup nowadays.

CJ

 

[Brantel]

Les has measured stress data from formal vibration surveys to guide his opinion, so I'd take the recommendation seriously. The prohibited power settings don't seem like something you would really miss anyway.

Dan, Trust me, I will trust Les's advice. Last thing I ever want is a blade departing my airplane!

I get confused however in the info that is out there. He said they have not tested the 1 mag/1 EI with advance...but have they?

On row 4 & 6 of this document: http://www.vansairforce.net/downloads/Hartzell_Engine-Prop_Approvals.xls

It states that "Combination not tested - similar to Std. Mags." so this would leave me to believe that it would be OK to run with no restrictions.

Here is Les's personal response to my query:

"If you use the electronic ignition with fixed timing, then you should be Ok with no restrictions.

If you use the variable timing feature, you might want to follow the 200 Hp engine limitations just in case."


Other questions that come to mind are related to the fact that the PMag also uses manifold pressure to control the advance and under high manifold pressures, it reduces the amount of advance basically back to normal mag timing.

I know I can either live with the restrictions or I can use the software for the Pmag to limit the advance back to regular mag values.

Just want to fully understand all I can about this subject before I do something stupid.

 

[DanH]

Because of Hartzells operating restrictions that WW does not have, and the performance.

From the Whirlwind 200RV manual:

Here is Les's personal response to my query:

"If you use the electronic ignition with fixed timing, then you should be Ok with no restrictions.

If you use the variable timing feature, you might want to follow the 200 Hp engine limitations just in case."

Sounds sensible to me.

 

[RV7ator]

Brian,

I adhered to the mp/rpm limitation on ship #1 before Hartzell lifted it for 180hp. It's easy to live with. Full power, no problem. Cruise, no problem, lots of power setting choices.

Now I'm running 200+ hp parallel valve engines, BA prop, dual EI, 9.5:1, and wondering just what we're afraid of. I can't complain about Hartzell's willingness to supply some test info, but to frame a limitation as "constant" raises the question of what is "constant". Some period of time is o.k; how long is that before it becomes "constant"? Engine limitations I've encountered state measurable limits, e.g., <5 minutes @ full power.

So we're into crowd-sourcing data!! As for me, I tend to avoid Les' sensitive region simply because it is easily avoided without operational hindrance.

John Siebold

 

[Chino Tom]

confusing

I have essentially the same set up Brian will have. Same prop, one mag and one Lightspeed. I don't understand the the 200 hp restriction recommendation. The O-360 A1A has 8.5:1 compression, not the higher
compression pistons of the 200 hp. Other than "better be safe than sorry",
would be nice to really know. Other than for several minutes during climb,
I don't operate in the warning range. When I read the prop sheet from
Van's, I assumed there were no restrictions for this set up. My logic being
(probably flawed), there are no changes in restrictions between mags only
and mag + EI for this engine with the other blades.

 

[rzbill]

From the Whirlwind 200RV manual:

Sounds sensible to me.

Thanks Dan.
Since I am not intimately familiar with the Whirlwinds, I was afraid of being smacked by data I was unaware of. Sounds like some testing has been done (obviously good thing) but maybe not to the detail of all the combinations done by Hartzell. I do want to make the point that I can see why. Testing all the different engine/prop combinations is expensive. Hartzell has had the luxury of time and history. Whirlwind has not.

 

[Brantel]

I have essentially the same set up Brian will have. Same prop, one mag and one Lightspeed. I don't understand the the 200 hp restriction recommendation. The O-360 A1A has 8.5:1 compression, not the higher
compression pistons of the 200 hp. Other than "better be safe than sorry",
would be nice to really know. Other than for several minutes during climb,
I don't operate in the warning range. When I read the prop sheet from
Van's, I assumed there were no restrictions for this set up. My logic being
(probably flawed), there are no changes in restrictions between mags only
and mag + EI for this engine with the other blades.

Your picking up on the same things I am Tom....

To me it does not make much sense. The 200hp engine is a much different creature than my 180hp standard compression engine.

Like you I wonder why the older blade models do not have different restrictions for different combinations of ignitions.

I am more than willing to take Les's word for it due to his "safe than sorry" comment and his experience. He knows best but I would sure like to see the combo's tested to see if we can eliminate these "suggested" restrictions.

I would volunteer my airplane as a test platform if they wanted to test my very common combo.

 

[F1Boss]

propeller restrictions

Hey Fellas:

An engine designer came up to me at OSH one year and started a discussion about engines. He was, at the time, involved in a 12 cyl diesel engine for aircraft use. Now, this sounds like a very interesting project, but why 12 cylinders?

Seems the reason was the amplitude of the vibrations imparted into the prop hub area. This assumes the crank nose is strong enough to take the loads. High amplitude pulses literally try to break the blades near the root, thus limiting the HP/torque that can be put into each pulse. I had also heard from the Hartzell reps doing a vibe cert test on my plane (2 blade BA prop on a 550-N Continental) that this was absolutely the truth. They confirmed that about 230HP was the limit for a 4 cyl engine, using standard hubs.

This would translate into 345HP on the 6 cyl engines, but the 6 cyl engines all have counterweights; this may change the equation. I do know that some of the props run at Reno on the higher HP Sport Class machines are limited to VERY few hours of operation, as some of these engines are putting out 700HP or more...

This amplitude problem is well known to PSRU designers.

Now, there are counterweighted 200HP lycs, and there are non-CW versions. My guess is the RPM ranges to stay out of are quite different for those 2 engines, given the same HP. I hope the spec sheet notes which engine the sheet refers to.

BTW the R2600 on the B-25 carries a similar RPM restriction placard.

Carry on!
Mark

 

[Sig600]

From the Whirlwind 200RV manual:

Sounds sensible to me.

Talked to Whirlwind in person about this. There's is a recommendation, simply because they haven't been able to test it yet to prove otherwise. The resonate freq of the carbon fiber blades however all but eliminates any chance of this.

I'm not selling props here, Hartzells makes a good product, I fly behind a variety of them every day. However anything that's limited in operation to avoiding max power in an aviation application to me is a non-starter. The other limitations are just nails in the coffin. YMMV, and that's fine. Just throwing out an option to the OP as I have a similar motor set up and have talked to a lot of the manufacturers on this very subject.

 

[Sig600]

If I understand correctly, you're saying they have no measured data so they recommend you ignore their recommendation.

No. WW said they only recommend it because they haven't proven that its not a problem. I.e. the engineering says its not an issue, they haven't validated it yet.

Show us, please.

Knock yourself out.

http://www.whirlwindaviation.com/contact.asp

 

[DanH]

For the curious, Marc Cook did a nice article detailing how a propeller vibration survey is conducted. You'll find it in the November 2006 Kitplanes, available online for subscribers.

 

[Brantel]

For the curious, Marc Cook did a nice article detailing how a propeller vibration survey is conducted. You'll find it in the November 2006 Kitplanes, available online for subscribers.

Thanks Dan, I will look it up!

 

[Brantel]

Just throwing out an option to the OP as I have a similar motor set up and have talked to a lot of the manufacturers on this very subject.

I love the look and the concept of the WW props. Brian Carroll proves they are very efficient props. I am sure they are awesome.

One of the primary reasons I am going with a CS/Hartzell is I need more weight up front.

Most likely I will just limit my Pmag's advance to and run with no restrictions. I am not sure there is much gained in these engines by advance anyway.

 

[hydroguy2]

......Most likely I will just limit my Pmag's advance to and run with no restrictions. I am not sure there is much gained in these engines by advance anyway.

I would not limit the Advance curve on your Pmags. I think you'll do have a significant gain advancing the timing at altitude. If I recall correctly, it doesn't advance until MP starts dropping. So down low you'll already be performing like a Std Mag.

Down low my plane isn't much different than the other 7's. But get me up to 9500 or above and she works pretty effectively.

BTW...my WW200 has restrictions and I follow them...well mostly.

 

[Brantel]

For the curious, Marc Cook did a nice article detailing how a propeller vibration survey is conducted. You'll find it in the November 2006 Kitplanes, available online for subscribers.

Thanks Dan, I will look it up!

I checked out that article. I retract my offer to use my plane for testing. 5 days of torture test with ~80lbs of gear sounds a bit much. The ground test alone in a RV sounds like it would be hard due to CHT limits.

Looks like Hartzell takes their testing very seriously. Hopefully modern technology has helped them out in the equipment they use.

 

[Sig600]

Looks like Hartzell takes their testing very seriously. Hopefully modern technology has helped them out in the equipment they use.

True statement, the issue we face in the exp world is that there is not standardization to our applications. Motors, ignitions, etc. Hartzell just can't test every single one of them.

As for your comment on needing the weight up front, I'm building a -7 as well and the weight issue is definately on my mind.

You just rebuilt your panel to a G3X setup right? Have you reweighed your airplane since then? Stein is building my G3X setup now.

 

[Brantel]

You just rebuilt your panel to a G3X setup right? Have you reweighed your airplane since then? Stein is building my G3X setup now.

Yep, the result was that it did not chance much. The screens are really light weight and the stuff removed pretty much offset the stuff added so it was almost a wash.

 

[miyu1975]

Brian, what happens at 9500 with the b curve in place.. curious as I am still using the A curve.

Ps..sorry for thread drift....although I have a hartzell cs and io 360 a1a, hartzell told me the rpm restriction is 2000 tp 2350, no mp restriction. That was not for EI, although I abid by the rpm restriction.

 

[Brantel]

Brian, what happens at 9500 with the b curve in place.. curious as I am still using the A curve.

Ps..sorry for thread drift....although I have a hartzell cs and io 360 a1a, hartzell told me the rpm restriction is 2000 tp 2350, no mp restriction. That was not for EI, although I abid by the rpm restriction.

You must have 7666 blades?

The default B curve is just +5 degrees more advanced than the A curve.

The default A curve max advance is 34? and the default B curve max is 39?.

The B curve can be changed by the user in regards to how much it is offset from the base curve and what its max advance limit is. This can be done with the EICAD software or Bill's EI Commander.

The Curve, RPM and MP all factor into what actual advance the ignition is producing.

In high MP situations, the ignition runs with little to no advance. In lower MP situations, it is allowed to run into the advanced ranged based on the curve/RPM/MP.

So up high at 9500ft, most likely even at WOT, the MP is in a range where there is some good advance and one might see some performance gain.

 

[miyu1975]

Yes..I have the 7666 blades.

Think I will just pull the jumper then and go to the B curve, don't yet have the EI commander. thanks brantel.

 

[Omega232Devils]

Home brew EI commander

Brian,
Don't you still have your home brew EI commander? The one you built to show you the status of the PMAGs?

I am asking because I don't think limiting the advance is what you want to do. As already mentioned MP is what drives the PMAGs, so the higher MP, they are going to be firing like basic MAGs. My point being, you could use your EI monitor setup to make sure the PMAGs at higher MP are not advancing, thus keeping your out of the restricted range. If you notice the PMAGs advancing at higher MP (you have a bigger problem than worrying about your prop restrictions at the moment), but you could increase or decrease the RPM to avoid the region.

Dan

 

[Brantel]

Brian,
Don't you still have your home brew EI commander? The one you built to show you the status of the PMAGs?

I am asking because I don't think limiting the advance is what you want to do. As already mentioned MP is what drives the PMAGs, so the higher MP, they are going to be firing like basic MAGs. My point being, you could use your EI monitor setup to make sure the PMAGs at higher MP are not advancing, thus keeping your out of the restricted range. If you notice the PMAGs advancing at higher MP (you have a bigger problem than worrying about your prop restrictions at the moment), but you could increase or decrease the RPM to avoid the region.

Dan

Yes I do and when I have used it, it does prove that the Pmag does not advance the timing during high MP operation.