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Prop

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Posted

Getting ready to order a prop for the Hirth. Considering everything, looking like a 3 blade 68" is the best option for a 2.59/1 gearbox and max 5500 RPM w/55 HP.  Anybody have any pro's or con's to speak of?

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Posted (edited)

My buddy that had the A model Avid with the same engine as you had a 3 blade IVO 64", and later went to a 2 blade 66" powerfin.  Had better performance with the powerfin.  I have a pair of LH 66" warp drive blades, but no hub. Warp's cheapest hub is $105.  JImChuk

PS  3 blade was smoother, but not as efficient as the 2 blade

Edited by 1avidflyer

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Posted

I've got a Warp Drive 3 bld HP hub that came with the engine and 60" blades. I was just going to order new blades for the hub. All reports that I can find on props state that 68" 3 blade is about the best for around 2.59/2.58 ratio. Most say the 2 blade gives better cruise and the 3 blade gives better T/O and climb performance.  I'll give Hirth a call and see what they recommend. I like the 2 blade but the 3 does sound quieter and smoother in normal use. Way too expensive for the "gimmie prop" way. As in gimmie that prop over there and I'll try it.

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Posted

On my Kitfox 1, I tried a two blade Warp, that same 64" three blade IVO, and a 3 blade 68" IVO.  Not much difference between the two IVOs, but the 2 blade Warp was way better in both climb and cruise at same RPM.  It did have the taper tips, not the square tips.  Don't know how much that helps. That was with a 582 with 2.58 ratio.  Cheapest new Warp 2 blade square tip is now $540.  JImChuk

https://warpdriveinc.com/product-category/complete-propellers/
 

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Posted

I measured everything today and can run a 70" max dia. prop, but will 55HP handle it is the question. A 2 blade standard hub WD from AS&S is around 485.00.  I might consider getting one to test and experiment with till I know from the results. I am not surprised that the 2 blade performed better on your model 1. A lot of factors come into play with props on different engines, airframes and ratios. I like the looks of a 2 blade better. I am curious about T/O performance of 2 vs. 3 blades difference. Anything less than 100' difference is not an issue since weight, pilot ability and technique can easily add 100' on any aircraft or remove it.  And if a 100' makes the difference of ending up in the trees or weeds, then I probably shouldn't have been there to start with or should have been in a helicopter.

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Posted

I think 70" would be to long on the 55 HP.  I ran that on a 582 with 2.58 ratio.  If you have to much prop, it may make more drag then pull cause you will have to run it so flat to make the RPM.  If I remember right, Joey and John before him ran a 70" square tip warp on the 582 with C box at 2.62 ratio.  Worked good for them.  My takeoff roll was much reduced with the two blade.  You mention 100', and that might be about what it was, but if we're are talking maybe 300' and 200'.  That's a 1/3 improvement.  JImChuk

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Posted

I think 70" would be to long on the 55 HP.  I ran that on a 582 with 2.58 ratio.  If you have to much prop, it may make more drag then pull cause you will have to run it so flat to make the RPM.  If I remember right, Joey and John before him ran a 70" square tip warp on the 582 with C box at 2.62 ratio.  Worked good for them.  My takeoff roll was much reduced with the two blade.  You mention 100', and that might be about what it was, but if we're are talking maybe 300' and 200'.  That's a 1/3 improvement.  JImChuk

What would you advise? I am an A&P, not a prop guy. My experience with props are strictly FAA regulated.  I don't really know what or how a 66" or 68" would perform with 55 hp. I do think a 70" could be a little too much prop for the Hirth. Wonder what the 503 Kitfoxes and Avid's ran? Maybe a call to Warp Drive would provide some answers?

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Posted

My Hirth dealer just E-mailed me and said a 70" 2 blade would work really well since the Hirth 55 HP engine puts out enough torque to turn it. He did say I could always cut it down to 68" if necessary. Which still poses more questions than answers.

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Posted

Well the Hirth dealer should know his engines.  Like he said, you can always cut it down.   Big difference between the square tip and the taper tip though which maybe should be considered.  The square tip is about 3" wide at the end, the taper tip is about 1 1/2" wide.  Lots of extra surface with the square tip to push against the air.  JImChuk

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Posted

I just talked to him and we was comparing the 55 HP 3202 to the 65 HP 3203 engine. The 3202 is more torque than the 65hp and can handle at least 4 deg more pitch than the 65 can. Most 3202 55 HP engines are running at least 15 deg of pitch and pushing static redline. The 65HP engine might be a tad over rated in the HP range. But its a gamble I'll have to take. He has always been straight with me for 9 years that I have been dealing with him.

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Posted

I suppose it all depends on where the power curve comes in.  I guess I would follow his recommendations.  JImChuk

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Posted

The Hirth dist and two dealers said the same thing. A 70" two blade is the best prop for that engine. So that issue solved!

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Posted

Have been reading some older info on Warp Drive prop failures, anybody ever have any issues with hubs or blades cracking? Hitting rocks or pavement doesn't count!

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Posted

Warp drive props are good in my opinion.  (for what ever that's worth):lmao:Had them on 3 different planes.  Over 500 hrs at least for me.  JImChuk

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Posted

Probably old outdated information. Way too many WD props in use for there to be a real problem.  There reports were at least 10-15 years old. Probably like the negative reports out there on Rotax, Hirth, or pick about any aircraft item.

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Posted

Just did a little checking as well, seems more problems on direct drive engines like VW and Lycoming.  I've put quite a few hours on the Warp on my Jabiru though.  No problems yet.  JImChuk

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Posted

Might have something to do with a dampener not being used on direct drive engines. No shock absorbing coupling like on a gearbox or belt drive. Prop does take a heck of a shock attached to a solid crankshaft. But this thought could be all hogwash too. Never read of one failing on a gearbox or belt drive system.

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Posted

Daryl at Warp Drive confirmed that the failures were from 25 years ago and only on the Jab and IO-240 engines. No failures since!  He also confirmed what my dealer said about the 70" prop.

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Posted

Did he say square tip or taper tip, or did he make a distinction?  I do have a couple of 70"  taper tips with nickel leading edge protection blades.  I don't think they have ever flown, only ground run.  JImChuk

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Posted

He did not specify.

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