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Metal Props and Electronic Ignition

mike newall

Well Known Member
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Has anyone got any information regarding restrictions placed by the prop manufacturers about running metal c/s props with electronic ignition ? We are not talking high compression or tricked up motor, just electronic such as Electro-Air or P-Mags etc.
 
I?ve got a Hartzell blended airfoil C/S prop on mine. The prop manual shows no restrictions for using electronic ignition.
 
Never heard of a concern like this. I?m trying to imagine a difference that the prop would see. The fuel should burn more completely, but I do not think the rate of burn increases with E.I. so I don?t imagine there are torque spikes. -
If anything an E.I. engine will run smoother. What have you heard to make you ask?
I have an O-360-A1A running duel P-mags with a Sensench FP.
 
And technically, "electronic ignition" has nothing to do with it.

The issue is advanced timing, not the method of generating a spark. A magneto set for advanced timing would net the same result.

It's important to remember, for two reasons. First, there are now multiple EI's available which enable fixed timing or limited advance. Second, an increasing body of evidence says the angle valve engines don't respond to highly increased advance like the parallel valve engines.
 
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Second, an increasing body of evidence says the angle valve engines don't respond to highly increased advance like the parallel valve engines.

That in itself is ironic, given angle valve engines generally incorporate pendulum absorbers.

Dan:

Not sure what you mean by this. Is the parallel valve more or less forgiving? Please expand a bit on it. I have a P-Mag on one side and Slick mag on the other of the IO-390 in the -14A. My plan is to go to dual P-Mags when the Slick is replaced as I have had zero problems with the P (or the Slick for that matter). Would like to know more about what additional information lies between the lines of your post.
 
All good points, well presented.

Our guys seem to have an issue with EI and metal props, I think it may be historic and conservative.

I agree that the method of ignition should make no difference, there has been advice from Hartzell about EI on their props but I don't know how long ago and whether they still apply it.

What I do know is that our dual P-Mag install on our IO-360 has been perfect since 2010, but we are on an MT wood/composite prop which our chaps seem happy with.

We are trying to move forward onto SDS injection/ignition on an IO-540 powered 10. Early days but it will be a lot of work to allow it to be installed. Our lot have a big issue between 2 place and 4 place airplanes which is a historic thing again. Huge advances have been made over here over the last 5 - 10 years, we just need to keep moving forward and satisfying the regulators.
 
Harmonics

We had this question raised in the UK, the reason given for questioning the set up by the LAA is that they argue that the harmonincs of the crankshaft will be changed.

As a result all applications are treated as what they call prototype modifications, even though similar engines have run for a very long time with the set up. I contacted a number of owners with the same engine, prop as mine and found one with 1000 hours on the set up, with no issues.

Mine being an 0-320 E2A with 8.5/1 pistons, so theoretically a160hp, with two PMags, and at the moment a Sensenich metal FP. A lot of RV and higher performance aeroplanes over here have similar set ups.
 
Not sure what you mean by this. Is the parallel valve more or less forgiving? Please expand a bit on it.

Not a question of more or less forgiving. As compared to an parallel valve, the angle valve merely requires less advance to reach optimum performance.

Remember, advance is compensation for finite burn rate. A better combustion chamber and port design (faster burn) requires less advance to result in peak pressure at the optimum point ATDC.
 
That's what Superior thought when they retarded the spark on the XP-400 angle valve engine from 25 to 20 degrees before top dead center.
Didn't work and they still broke cranks.
 
I have a hartzell constant speed with dual Lightspeed ignition. I bought the plane from the original builder. Documentation came with the plane from hartzell basically stating there are harmonics at play and for that reason there is a RPM / MP range that is to be avoided.
 
It really has to do with what prop on what engine. Some props have restrictions and some don't. The Hartzell BA prop does not have any restrictions whereas Hartzell props with F7666 & F7068 blades do. As for increased harmonics, adding additional forces increases the restriction problem, such as 10:1 pistons, more that stock advance, etc. I just had a conversation with Hartzell about this very subject and I changed props. A harmonic will actually split a blade in half during flight.
 
From Hartzell Service letter HC-SL-61-61Y.

?The engine models listed are the configurations tested. Modification to the engine that alters the power of the engine models listed in Table 2 during any phase of operation have the potential to increase propeller stresses and are not approved by this list. Such modifications include, but are not limited to, the addition of a turbo charger or turbonormalizer, increased boost pressure, increased compression ratio, increased RPM, altered ignition timing, electronic ignition, full authority digital engine controls (FADEC), or tuned induction or exhaust. Also, any change to the mass or stiffness of the crankshaft/counterweight assembly is not approved by this list.?

The same statement is in the prop manual 115N for the compact hub propellers.

There is also a statement from Hartzell somewhere saying that they tested certain prop and engines with electronic ignition.
 
This from Hartzell Manual 115N:
AIRWORTHINESS LIMITATIONS
Propeller: HC-C2YR-1BF/F7666A-2Engine: Lycoming O-360-A1A rated at 180hp at 2700 RPM equipped with Lightspeed Plasma II electronic ignition Max. Diameter 74 inches Min. Diameter 72 inches
Operating Restriction: ?Avoid continuous operation between 2000 and 2250 RPM. Operation above 2600 RPM is limited to takeoff. As soon as practical after takoff, the RPM should be reduced to 2600 RPM or less.?

This from http://hartzellprop.com/pilots/kit-builders/glasair-ii-ii-srg-io-360-180-hp-new-prop-design/ (Listed under Glasair)
LYCOMING (I)O-360-B1A RESTRICTIONS:
Hartzell Propeller Model HC-C2YR-1BF/F7496 is satisfactory vibrationwise mounted on Lycoming model O-360 A1A rated at 180HP at 2700 RPM and equipped with magneto ignition and/or Lightspeed Plasma II or LASAR electronic ignition installed in similar single engine tractor aircraft with the following operating restrictions.
1) Do not operate above 22″ manifold pressure below 2350 RPM.
2) Operation above 2600 RPM is limited to takeoff. As soon as practical after takeoff the RPM should be reduced to 2600 RPM or less.
The propeller diameter limits are 74 to 72 inches.

Cheers, David
KBTF - RV-6A
 
This from Hartzell Manual 115N:
AIRWORTHINESS LIMITATIONS
Propeller: HC-C2YR-1BF/F7666A-2Engine: Lycoming O-360-A1A rated at 180hp at 2700 RPM equipped with Lightspeed Plasma II electronic ignition Max. Diameter 74 inches Min. Diameter 72 inches
Operating Restriction: ?Avoid continuous operation between 2000 and 2250 RPM. Operation above 2600 RPM is limited to takeoff. As soon as practical after takoff, the RPM should be reduced to 2600 RPM or less.?

This from http://hartzellprop.com/pilots/kit-builders/glasair-ii-ii-srg-io-360-180-hp-new-prop-design/ (Listed under Glasair)
LYCOMING (I)O-360-B1A RESTRICTIONS:
Hartzell Propeller Model HC-C2YR-1BF/F7496 is satisfactory vibrationwise mounted on Lycoming model O-360 A1A rated at 180HP at 2700 RPM and equipped with magneto ignition and/or Lightspeed Plasma II or LASAR electronic ignition installed in similar single engine tractor aircraft with the following operating restrictions.
1) Do not operate above 22″ manifold pressure below 2350 RPM.
2) Operation above 2600 RPM is limited to takeoff. As soon as practical after takeoff the RPM should be reduced to 2600 RPM or less.
The propeller diameter limits are 74 to 72 inches.

Cheers, David
KBTF - RV-6A


That is the info I was referring to.
 
That's what Superior thought when they retarded the spark on the XP-400 angle valve engine from 25 to 20 degrees before top dead center. Didn't work and they still broke cranks.

I'm not sure what Superior thoughts you refer to, but 20 and 25 are base timing figures with little bearing on the subject under discussion.
 
As you were saying "That in itself is ironic, given angle valve engines generally incorporate pendulum absorbers." Since you were relating to crankshafts with pendulum absorbers. My comment was only an association. That's what the XP-400 had.
 
As you were saying "That in itself is ironic, given angle valve engines generally incorporate pendulum absorbers." Since you were relating to crankshafts with pendulum absorbers. My comment was only an association. That's what the XP-400 had.

Ahh. I'll go back and delete that note, so as to not further confuse the issue under discussion...propeller blade stress increase due to increasing ignition advance.
 
This from Hartzell Manual 115N:
AIRWORTHINESS LIMITATIONS
Propeller: HC-C2YR-1BF/F7666A-2Engine: Lycoming O-360-A1A rated at 180hp at 2700 RPM equipped with Lightspeed Plasma II electronic ignition Max. Diameter 74 inches Min. Diameter 72 inches
Operating Restriction: ?Avoid continuous operation between 2000 and 2250 RPM. Operation above 2600 RPM is limited to takeoff. As soon as practical after takoff, the RPM should be reduced to 2600 RPM or less.?

This from http://hartzellprop.com/pilots/kit-builders/glasair-ii-ii-srg-io-360-180-hp-new-prop-design/ (Listed under Glasair)
LYCOMING (I)O-360-B1A RESTRICTIONS:
Hartzell Propeller Model HC-C2YR-1BF/F7496 is satisfactory vibrationwise mounted on Lycoming model O-360 A1A rated at 180HP at 2700 RPM and equipped with magneto ignition and/or Lightspeed Plasma II or LASAR electronic ignition installed in similar single engine tractor aircraft with the following operating restrictions.
1) Do not operate above 22″ manifold pressure below 2350 RPM.
2) Operation above 2600 RPM is limited to takeoff. As soon as practical after takeoff the RPM should be reduced to 2600 RPM or less.
The propeller diameter limits are 74 to 72 inches.

Cheers, David
KBTF - RV-6A

Keep in mind that the above approval is for a very specific engine and ignition configuration.
This came as a result of extensive testing done during a collaboration between Harzell test engineering and Vans Aircraft in the early 2000's.
At the time, the test results surprised the Hartzell engineers and it resulted in a whole new perspective regarding their involvement in supplying propellers for the experimental market.

I think the best point to be taken from their published data is that what may seem to be a very minor modification, could induce just enough change that it would push a particular engine/prop. combination outside of the originally safe operating envelope.
The bottom line is that if you can't find a specif approval for the exact configuration you are running or considering to run, you are operating in a realm of the unknown.
 
And technically, "electronic ignition" has nothing to do with it.

The issue is advanced timing, not the method of generating a spark. A magneto set for advanced timing would net the same result.

It's important to remember, for two reasons. First, there are now multiple EI's available which enable fixed timing or limited advance. Second, an increasing body of evidence says the angle valve engines don't respond to highly increased advance like the parallel valve engines.

I recall reading that the bigger factor between EI and mags (beyond the obvious timing changes) was how they are triggered. In the case of crank position trigger, the spark timing is more accurate and can contribute to vibration, while mags triggered off of the backside of the case tended to drift around ever so slightly.

After reading that, I messaged Hartzell with:

I purchased this prop years ago for my bearhawk. I have a io-540-c4b5 250hp engine and plan on running the gov up to 2700 to get the extra 10hp because the internals are the same as the 260hp model.

As far as I know this all works together, but I also want to run electronic ignition and wanted to know if there are any known problems with this engine, prop, and EI combination.

They responded with:

Hello Matt,

Thank you for contacting Hartzell Propeller.

Our engineering group states that the propeller can be used up to 2700 RPM without operating restrictions. The propeller diameter is limited between 84 and 76 inches.

We do not have any data on electronic ignition with this propeller/engine combination. Use of electronic ignition is not necessarily prohibited, but it would be at your risk.

If you have any additional questions, or if we can be of further assistance, please do not hesitate to contact us.

At this point I'm not sure what I'm going to run. I like the simplicity of the surefly, but I also like the tunability of the CPI-2, especially if I run any amount of mogas.

schu
 
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