Prop for your 1/2 vw engine

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Rockiedog2

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Tony
I thought all that kinda stuff was normal. I'd like to trade problems with you...my right tank just developed a big fuel leak. It's in the wing and inside the fabric. Fun. And trying to get a new plane ready to go to OSH. I just didn't really need this...:mad2:
well, we'll get it...
 

Himat

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I am comparing props made by the same manufacturer. I am also comparing these props to each other. Meaning I am dealing with two prop companies. I have two props from each company. All props are marked 54x24. I understand results or comparing one company to the other, one will get different results or could. But what puzzles me is why a prop company can not make two props alike. Nothing has changed on this airplane but the prop. The results should be the same when comparing two props make by the same company. If this can not be then one is just shooting in the dark when it comes to the prop they order. No two are alike not even from the same company. I have a hard time with this or dealing with this. I may never get the correct prop if this is indeed true, no wonder a buddy of mine started making his own props.

Tony
As TFF say, there are reasons why not two props from the same company is exactly the same. On the other side, if nothing else is stated I would expect them to be close. At least if the props are a “standard” item. If the manufacturer makes all props to order and specifications, they should rather have a serial number and datasheet that are more informative. If not the customer is at loss, and that is no good.

One thing I would have done is to measure the props myself. Put them on flat table and measured pitch, chord length and thickness at four or more stations along the blade. Maybe, more measurements to and made an attempt to figure out the airfoil. At that stage you are on your way to figure out to make your own prop.
 

N8053H

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As TFF say, there are reasons why not two props from the same company is exactly the same. On the other side, if nothing else is stated I would expect them to be close. At least if the props are a “standard” item. If the manufacturer makes all props to order and specifications, they should rather have a serial number and datasheet that are more informative. If not the customer is at loss, and that is no good.

One thing I would have done is to measure the props myself. Put them on flat table and measured pitch, chord length and thickness at four or more stations along the blade. Maybe, more measurements to and made an attempt to figure out the airfoil. At that stage you are on your way to figure out to make your own prop.
You can see in this pic this prop does indeed have a serial number. I am calling Steve at Tennessee prop this morning. Lets see what he tells me to do here. I to believe these props should have been close to one another in terms of performance. Maybe not the same from one company to the next. But each manufacturer should be close with the same prop. I am not finding this to be true and would like to know why. I watched a man make a prop on a duplicator and when he was done it looked like he had two identical props. I did not measure anything but they sure looked to be identical. I would think if someone ordered two props from the same company and both props are the same. I would expect the performance of each prop to be maybe not identical but close. I am not finding anything close or identical.

SAM_5684.jpg
 

MikePousson

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As someone who understands mechanical properties of a carved propeller, I'm a total newbie. A propeller carved with a duplicator would, in all likelihood, be identical to within a percentage point of the pattern, all things being the same. The only difference between two different props carved from the same pattern would be the way it was laminated to begin with. Wood has known characteristics in that it's always moving within its structure. If grain orientation is no taken into consideration when laminating, the prop will not be the same as one that did considering the grain direction. One missed grain direction while laminating will change everything. Opposing grain orientations will keep shape changing to a minimum. But all that being said, another prop that will be made from a different batch lumber will have its own properties,even with correct orientation of the grain pattern.
About the only way two props will be very close in performance is if they were both carved from the same flitch of lumber from a single cant with correct grain orientation. Even then, there will be differences.
 

N8053H

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The man using the duplicator explained to me that he uses what is called a blank. Each prop is made from this blank. This blank is not finished as in covered or varnished its a bare blank.
 

MikePousson

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The man using the duplicator explained to me that he uses what is called a blank. Each prop is made from this blank. This blank is not finished as in covered or varnished its a bare blank.
Yes, it is the exact pattern for the length and pitch of the prop being made. It is the master copy. Never used for anything else. But, the glued up stock that is being carved on has to be all oriented in the proper direction.
As an example, glue up five pieces exactly as they come off the sawmill blade with the growth rings all pointed in the same direction, over time, it will cup way from the crowns of the rings. That's just wood.
Being props are tapered and have pitch, you really can't tell if the boards were flipped the opposing direction.
Gluing two pieces of wood together with the grain "rainbows" kissing will negate almost all movement as they both try to pull opposite.

I'm building a deck right now (instead of plane building), and all the deck boards a laid with rings up, like a rainbow, because when they cup, I want the cup on the underside so as not to hold water.
 

BBerson

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Tony, the diameter and pitch is only two points of a prop description. You keep saying that all 54-28 props should be the same, but that isn't the case for homebuilts. For example, the blade width is wider for a larger engine but same diameter and pitch. For RC models, the diameter and pitch is all anybody uses and same for metal props on certified airplanes.
But for a Homebuilt the wood prop should be custom made because each Homebuilt is unique with different drag and weight.
So, the prop maker needs to estimate horsepower, weight, drag, and if the owner wants more of a climb prop or cruise prop or half in between. It's a tough job because they can't assume the owner knows the horsepower of his engine. Because nobody knows the horsepower on any particular day. They must assume a lower horsepower or the engine will be bogged down and unsafe for takeoff. There is no standard prop.
If you are near the weight limit of your 1/2VW, then more careful detail design of the prop is needed. And more prop experimentation is needed.

The weight given on your plans is mostly meaningless, since designers numbers are usually optimistic, at best. I am asking if other designs are flying the 1/2VW at 600 pounds.
 

N8053H

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Tony, the diameter and pitch is only two points of a prop description. You keep saying that all 54-28 props should be the same, but that isn't the case for homebuilts. For example, the blade width is wider for a larger engine but same diameter and pitch. For RC models, the diameter and pitch is all anybody uses and same for metal props on certified airplanes.
But for a Homebuilt the wood prop should be custom made because each Homebuilt is unique with different drag and weight.
So, the prop maker needs to estimate horsepower, weight, drag, and if the owner wants more of a climb prop or cruise prop or half in between. It's a tough job because they can't assume the owner knows the horsepower of his engine. Because nobody knows the horsepower on any particular day. They must assume a lower horsepower or the engine will be bogged down and unsafe for takeoff. There is no standard prop.
If you are near the weight limit of your 1/2VW, then more careful detail design of the prop is needed. And more prop experimentation is needed.

The weight given on your plans is mostly meaningless, since designers numbers are usually optimistic, at best. I am asking if other designs are flying the 1/2VW at 600 pounds.
This is not a new airplane. It has hundreds of hours flown using a 54x24 prop. Nothing special about these props. They are all built the same for a 1/2 vw coming from Tennessee propeller. I have no idea about other manufacturer's. Speaking with Scott Casle, he said he buys all his props from Steve or Tennessee Prop. He said every one is like the next or made the same. He also told me to not change from a 54x24. He cared less what airframe this engine was going in. He said stick with that prop. Never have I seen 3650 in level flight using any other prop. I have used four to date. This one has had the highest RPM's of them all. We are not comparing four props from four different manufacturer's. We are comparing four props from two manufacturer's. But I am also comparing two props to each other from each manufacturer. I am finding noting to be consistent.

Tony
 

N8053H

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I just got off the phone with Steve at Tennessee prop. He has no idea why I am seeing the numbers I am. But get this. Steve is making me a new prop. He believes with the numbers I am seeing we can go with a 54x28. He is doing this free at no charge to me. He said the prop I have, there is nothing wrong with it and he will resale it. He told me to use this prop and watch my RPM's. When the new one comes in to remove this one and send it to him. What a man. My Hat goes off to him. A+ for Tennessee Propeller.

But I bet anything if I would have contacted that young lady at Culver she would have done the same. She was so very very nice. I did like that prop above any other when it comes to smoothness. My airplane never ran so smooth. I mean silk smooth. I have no idea why. But those Culver props are one of the best in this area. A+ to that company also. I really did not give them a chance to correct this. I just went with plan be. You cannot fault Culver for that.

Two good prop companies. But I will never understand what happened here comparing these props. This have left me more confused then ever when it comes to props. But hopefully it helps someone else.

Tony

P.S I will report the findings on my new 54x28 prop or the numbers I get.
 

Pops

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I just got off the phone with Steve at Tennessee prop. He has no idea why I am seeing the numbers I am. But get this. Steve is making me a new prop. He believes with the numbers I am seeing we can go with a 54x28. He is doing this free at no charge to me. He said the prop I have, there is nothing wrong with it and he will resale it. He told me to use this prop and watch my RPM's. When the new one comes in to remove this one and send it to him. What a man. My Hat goes off to him. A+ for Tennessee Propeller.

But I bet anything if I would have contacted that young lady at Culver she would have done the same. She was so very very nice. I did like that prop above any other when it comes to smoothness. My airplane never ran so smooth. I mean silk smooth. I have no idea why. But those Culver props are one of the best in this area. A+ to that company also. I really did not give them a chance to correct this. I just went with plan be. You cannot fault Culver for that.

Two good prop companies. But I will never understand what happened here comparing these props. This have left me more confused then ever when it comes to props. But hopefully it helps someone else.

Tony

P.S I will report the findings on my new 54x28 prop or the numbers I get.
Tony, like someone said, making props is a black art. The reason I never tried to make my own.
 

N8053H

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Tony, like someone said, making props is a black art. The reason I never tried to make my own.
And the reason this man makes his own props. He told me under that spinner is a square piece of wood. he only profiles the blades to the spinner. He makes his props with turned up tip, just like you see on the ends of his wings. he made those too.

https://www.youtube.com/watch?v=iGFD_R_3mYg
 

N8053H

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Steve at Tennessee prop said I should have the 54x28 prop next week. So now I have used a few different props, all being 54x24. Two being made by the same manufacturer. Blade design has more to do with engine loading or thrust of two props made alike.

Here are the two props I speak of:



View attachment 52615

View attachment 52616



Using the prop you see in the top pic. I saw rpm's of 3000 in cruise and a speed of around 70 mph, 25 on MP gauge. Using the prop you see in the bottom pic. I am seeing RPM's in cruise over 3400 rpm with a cruise speed of around 65 mph, 25 on MP gauge. Both prop produce the same top speed at WOT. One does it at a lot higher RPM.

After speaking with Scott Casler about what prop to use. He told me to make sure it was the thin blade design Tennessee prop makes. As you see in the first pic, that prop is not the thin blade. The second prop or pic does produce a lower CHT temp on climb out. The first prop was not bad but temps would get up to 450 on CHT's on climbout. Now this is using a probe under the spark plug. We all know these probes or sensors read 50 or more degree's hotter then if the sensor was mounted to the jug itself. I do not let these CHT go above 450 degree's. If you believe what these CHT gauges read in the first place. I use it for a base line and nothing more.

I also used a Culver Prop. The Culver by far was the best in terms of smoothness. I mean those props run so smooth. My airplane has never been so smooth as with a Culver. But the prop I used or they made for me did not have any thrust. After comparing these props now I know why. Its in the Blades. They are to small. The blade needs to be a little wider not thicker. I may work with this company and see if we can not come up with a good design for this engine. Culver prop sent me two props. the first was wrong. the bolt spacing was 4 inches. The second prop was what I needed. It had a 3 1/8th bolt spacing. The blades on the first prop was bigger then the blades on the second or the one with the smaller bolt pattern. I believe the people at culver thought if it had a smaller bolt pattern it also needed a smaller blade profile. This just is not the case. It should have had the same blade profile as the 4 inch bolt pattern. I did not take pics of the first culver prop with the 4 inch bolt pattern. But the blades were wider.

Here is that Culver prop with the 3 1/8th bolt pattern:

SAM_5532.jpg

I will update this thread when the new 54x28 props comes in and is installed and tested. More to come.

Tony
 

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N8053H

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I received and installed the 54x28 prop. What a difference this prop makes. My RPM's at WOT in cruise is now around 3100. All temps have come down. Oil temp never went over 150 degree's. CHT's are lower also. The engine runs so much smoother. My speeds went up by about 5 or so MPH. I only did a short flight around the pattern and I will get some video of this in action on my next flight. I should mention it was really hot out last evening when I took this flight. I believe DA was around 3000'. My field is at 570' or there about's. I really like this new prop.

Tony
 

N8053H

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An update for those who may be following this thread. I removed two inches off this 54x28 prop. Now its a 52x28 and I love it. I was looking for 3200 rpm's in cruise flight at WOT. Its a little over 3200 more like 3250-3300. But its perfect. I was also looking for 3000 rpm's in climb out and now I have that too.

Tony
 

Rockiedog2

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Hi Tony
Just a point of interest not really saying anything other than airport bums talking
I flew my Legal Eagle yesterday (with the same motor you got) and got new rpm data on it. We're rigged for different missions and the prop choices really show it. I'm currently running a Performance Props USA 5818. I was running a couple 5820s from same company and they were good but I wanted to see how far I could go with takeoff and climb performance so had Frank build me this 5818 then we tweaked it by thinning out the blades near the tips and getting a little drag off of it IIRC . It's astounding how it will come outa the hole...when shoving the throttle forward the motor instantly winds up to about 3400(kinda like a grenade goin off), takeoff roll is 100-150 feet and happens quick(2-3 secs) and once established in the climb at 45 it's turning 3650 and climbing near 900 fpm; that's pretty steep at that slow speed. The pilot is thoroughly entertained during the takeoff and climbout. Straight and level it'll willingly turn 4000+ but as expected isn't going anywhere very fast. At those rpms the prop tips exceed the recommended tip speed and howl like crazy but don't lose the bite...just a small example of a little extra performance that sometimes can be found outside the recommendations and traditional way of doing things. We just have to go there and see.
Both my Mikunis are dumping fuel on me out the bowl vents. That's been normal for the left one but the right one decided it wanted to do it too. I think that's pretty common with Mikinus. The floats are right and no trash under the needles. you runnin Mikunis?...does your do that? think I'll go into the right one and see whats goin on.
Your Avenger looks good they have nice lines. Stocky looking. I like that
 

N8053H

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Rockiedog2 I use a Zenith Carb mounted under my engine. I had all sorts of oil issue's turning my engine 3500 rpm and higher. The oil would foam and then start to fluctuate. Reducing the oil level helped this issue some. Once I slowed the engine down by loading it more I was able to raise the oil level back up some without the same fluctuation.

I believe on your setup with those carbs you install a fuel line or clear line on that vent. This line then has a hole in it. This is done for the reason you state. Fuel can be drawn out of that vent hole when in flight. It's been a long time since I fooled with one of these. But it seems to me there is a vent on both sides of those carbs. This line is hooked to both these vents. Then drill a hole in this line to vent it to out side air pressure. This should stop those vents from bleeding fuel from them.

Thanks for the comments. What size are these props you speak of? I have never dealt with this prop manufacturer.

Tony
 
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