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Airmaster whirlwind blades

 
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davidjoyce(at)doctors.org
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PostPosted: Tue May 09, 2017 5:08 am    Post subject: Airmaster whirlwind blades Reply with quote

I found the article by Bud Y and Jim B very interesting. I am very prepared to believe that the extra performance with the Whirlwind blades is due to the increased twist they have as my change from low twist to high twist Woodcomp blades added an extra 5kts - probably within experimental error directly equivalent to your improvement. I would be very interested to know what the twist on the Whirlwind blades is - measured in the change of incidence between the tip and 1/3 radius if one of you could take your Smart tool to a blade. Woodcomp figure is 24 degrees for the high twist.
Regards, David Joyce, GXSDJ


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h&jeuropa



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PostPosted: Sun May 14, 2017 4:10 am    Post subject: Re: Airmaster whirlwind blades Reply with quote

David,

We attempted to measure this yesterday. It is difficult to measure the incidence of the blade at the 1/3 radius point since the blade is not flat there. But making the level equidistant from the leading edge and the trailing edge at the point, the twist in the blade is around 14 deg.

The blade has quite an airfoil shape so perhaps that accounts for the improved performance rather than twist.

Jim & Heather


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Remi Guerner



Joined: 14 Dec 2010
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PostPosted: Sun May 14, 2017 5:25 am    Post subject: Re: Airmaster whirlwind blades Reply with quote

Yes the article by Bud and Jim in EF 89 is interesting. Those Whirlwind blades are beautiful and the new ferrules are not protuding outside the spinner anymore as they do with the WarpDrive blades, adding drag without thrust.
The possibility to upgrade an existing Airmaster/WrapDrive prop with the new blades is very tempting.
However the article is disapointing regarding the compared cruise performances of the WD and WW blades. Both Bud and Jim say they see a few more knots at the same power setting. I have analyzed in details the figures shown in the charts for the Monowheel and here are my comments:
1. Some speed figures are very wide spread, sometimes 10 knots for the same conditions, probably because the air mass was not as stable enough during the testing. As we are looking for a few knots differences, that makes the comparison a little bit doubtful.
2. The tendency is a speed increase of 2 knots with the WW blades at altitudes up to 14000 ft.
3. The testing was done on the Rotax 914 only. I assume there would be some similar speed improvement also with the normally aspirated 912S.
3. Surprisingly at 17000 ft. figures show that the WW are slower than the WD for 3 out of the 4 power settings used for the test.
So to summarize, sorry Bud, I do not see the 5 knots increase you are talking about. Regarding the alleged reduced fuel flow with the WW blades at a given power setting at the same density altitude, this is just not possible. That is the law of physics. If the fuel flow is lower, that is due to either a lower power setting or an inacurate fuel flow meter, not to the better prop blades.
To conclude I pass the following message to Airmaster: with the Airmaster/WD blades on my Monowheel, 912 ULS, one on board, full fuel, I consistently get 140 kts TAS at full throttle, 5000 RPM at 8500ft density altitude. If I could get the proof that those WW blades would increase my cruise speed by 5 knots in those conditions, I would place an order immediately!
Remi Guerner
F-PGKL


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Remi Guerner



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PostPosted: Sun May 14, 2017 5:30 am    Post subject: Re: Airmaster whirlwind blades Reply with quote

Jim,
14 degrees of twist for the Whirlwind! By comparison, the WarpDrive blade has 16 degrees of twist and the high twist Woodcomp 24 degrees. So should we ask Whirlwind to design a new blade with more twist ? That would at least improve ground cooling and possibly give us some more speed.
Remi Guerner
F-PGKL


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PostPosted: Sun May 14, 2017 8:21 am    Post subject: Airmaster whirlwind blades Reply with quote

Remi, The comparisons I did between low & high twist woodcomp props were rigorous, all early in the day and over water to eliminate the risk of catching an early thermal. They were also all done approaching the test conditions from above, that is doing a shallow dive from something like 100ft above the chosen altitude and then waiting for the speed to stabilise whilst flying level. They showed a clear 5 kt advantage at low & middle altitudes (Vne exceedable at 10,000ft so no comparison possible) but also a clear cooling advantage not just on the ground but in the air. The required 5 min full power climb boiled the engine with the low twist one but was achieved without incident with the high twist. It is worth restating that with twist of the order of 14 degrees either the tip will be stalled or the inner part of the prop will be in Beta mode at speeds of 100kts or more. Ask yourselves why all prop driven war birds or Red Bull racers and the like have props with 24 or 26 degrees of twist!
Regards, David Joyce, GXSDJ

On 2017-05-14 14:30, Remi Guerner wrote:
Quote:
Quote:
--> Europa-List message posted by: "Remi Guerner" <air.guerner(at)orange.fr (air.guerner(at)orange.fr)>

Jim,
14 degrees of twist for the Whirlwind! By comparison, the WarpDrive blade has 16 degrees of twist and the high twist Woodcomp 24 degrees. So should we ask Whirlwind to design a new blade with more twist ? That would at least improve ground cooling and possibly give us some more speed.
Remi Guerner
F-PGKL


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PostPosted: Sun May 14, 2017 3:56 pm    Post subject: Airmaster whirlwind blades Reply with quote

Hello  trying to figure out how I would renew my membership in the Europa Club. I joined last year ,2016 , while at SUn n Fun.  My name is Bill 
Moreland from Pa.   I would love to renew my membership with your help. thank you,  Bill


Will be looking for your info and again thanks
On Sun, May 14, 2017 at 8:10 AM, h&amp;jeuropa <butcher43(at)att.net (butcher43(at)att.net)> wrote:
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--> Europa-List message posted by: "h&amp;jeuropa" <butcher43(at)att.net (butcher43(at)att.net)>

David,

We attempted to measure this yesterday.  It is difficult to measure the incidence of the blade at the 1/3 radius point since the blade is not flat there.  But making the level equidistant from the leading edge and the trailing edge at the point, the twist in the blade is around 14 deg.

The blade has quite an airfoil shape so perhaps that accounts for the improved performance rather than twist.

Jim & Heather




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Remi Guerner



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PostPosted: Tue May 16, 2017 1:33 am    Post subject: Re: Airmaster whirlwind blades Reply with quote

David,
I am not questioning your measurements but your comparisons are between two Woodcomp props, not between Airmaster/WarpDrive and the high twist Woodcomp. The low twist narrow blade Wood comp is notoriously bad as far as cruise speed is concerned. We even have one of our french Europa owner who recently went back from this prop to his old ground adjustable WD, because the Woodcomp was consistently reducing his cruise speed.
Remi


[quote="davidjoyce(at)doctors.org"]Remi, The comparisons I did between low & high twist woodcomp props were rigorous, all early in the day and over water to eliminate the risk of catching an early thermal. They were also all done approaching the test conditions from above, that is doing a shallow dive from something like 100ft above the chosen altitude and then waiting for the speed to stabilise whilst flying level. They showed a clear 5 kt advantage at low & middle altitudes


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PostPosted: Tue May 16, 2017 3:18 am    Post subject: Airmaster whirlwind blades Reply with quote

Remi, I have no views nor evidence on the relative merits of different firms propellers, just strong views on the desirability & greater efficiency of high twist blades. Nevertheless I am surprised to hear your views on the low twist Woodcomp blades as they had a measured efficiency of 85% as I remember it, which I believe is an industry standard, and my plane certainly didn't hang about in comparison to others. I had in fact first become interested in Woodcomp back in 2000 when at the Prague fly out I saw the Europa company 914/Airmaster plane take off together with Tom Justic's 914/Woodcomp SR2000, with the latter climbing at what appeared to be at least 10 degree steeper gradient. It would make me wonder whether your friend had his pitch angles set appropriately.
It would be good to have some rigorous comparisons done, and I would happily cooperate with my new Sr3000/N/W if someone has an Airmaster and we find they could be swapped over without any major trouble.
Regards, David Joyce, GXSDJ


On 2017-05-16 10:33, Remi Guerner wrote:
Quote:
Quote:
--> Europa-List message posted by: "Remi Guerner" <air.guerner(at)orange.fr (air.guerner(at)orange.fr)>

David,
I am not questioning your measurements but your comparisons are between two Woodcomp props, not between Airmaster/WarpDrive and the high twist Woodcomp. The low twist narrow blade Wood comp is notoriously bad as far as cruise speed is concerned. We even have one of our french Europa owner who recently went back from this prop to his old ground adjustable WD, because the Woodcomp was consistently reducing his cruise speed.
Remi


[quote="davidjoyce(at)doctors.org"]Remi, The comparisons I did between low & high twist woodcomp props were rigorous, all early in the day and over water to eliminate the risk of catching an early thermal. They were also all done approaching the test conditions from above, that is doing a shallow dive from something like 100ft above the chosen altitude and then waiting for the speed to stabilise whilst flying level. They showed a clear 5 kt advantage at low & middle altitudes


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budyerly(at)msn.com
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PostPosted: Wed May 17, 2017 5:32 pm    Post subject: Airmaster whirlwind blades Reply with quote

Remi,
The Tests were done over a short period of time swapping blades and rebalance over a couple of weeks at as close to the same conditions as possible. Then flown again to try to verify the test points about a month later. The scatter of the points I will discuss below.

It has been a while, and the data Jim and I used was different because of test aircraft and location. He has a mono with early 914, and mine is a trigear with a new TCU on the 914.

Of course each experimental plane is slightly different from builder to builder, model to model, and so is our test data. Heck, the same day test in the same airplane gets frustrating also. For instance, setting 35 inches one day may look like 35 inches on my gauge, but it is actually my Rotax defined stop for the 100% throttle position. In reality even though the test conditions were relatively close in temperature and pressure altitude, I chose to record the temp and fly pressure altitude and let the density altitude be up to you all to decide if you wanted to use. Jim flew at the same computed density altitude. The Tach setting in the Airmaster is fairly accurate, but as any analogue system, has a dead band of plus or minus about 50 RPM, so each setting is going to vary day to day or run to run. I only flew to 15,000 feet (the operational ceiling by Rotax) as the temp, throttle position, TCU computer settings, turbo cable setting and other factors such as cowl heat, does cause a variation in test data. I did runs at 1000 feet, 2500 and each 2500 foot increment to 15,000. I flew for at least two minutes or as required to get steady state results at each power setting for each altitude trimmed for steady flight with limited thermals.

I have an EI fuel flow meter and it is quite accurate over 10 years of flying. But the throttle position used by setting a MP by eye, varied only a tiny bit, but that made fuel flow variations at the higher power settings especially. You are right, that better economy comes from the increase in speed with the same power setting not the same power setting and RPM.

As I only have 914 engines to test with stock intake and cowls, it is true the 912S especially took a back seat to my testing, as I just didn’t have aircraft available. Few 912S owners have constant speed propellers over here unlike in Europe. I started using a local Experimental Pipestral for 912S tests. Testing is not complete, as the test was done against a Woodcomp that shed a blade. The other has hit its 300 hr. mandatory removal and factory inspection and is out of service for an unknown time. So I am still stuck with my 914s for the time being.

I tested the two blade Sensenich, the three blade Warp and the Whirlwind against each other on my Europa. All have their good and bad points. Jim Butcher was lent my Whirlwind test blades to see if there is a correlation of data.

In general, at low altitude and low RPM you can put any club on the front of a Europa and the speeds do not change appreciably. That is a nasty thing to say, but the static thrust difference between 6 different manufacturers is virtually the same in head to head tests. Comparing ground adjustable LSA aircraft (Breezer) using various blades (GA, Woodcomp, Sensenich, Whrilwind and Warp Drive) the Breezer dealer settled on the Sensenich and Whirlwind for his clients as they were nominally better at cruise.

For me I stuck with blades that would fit the AP332 hub (the Sensenich and Woodcomp would not fit due to their shank size), the GA was not considered as it was terribly slow. The 332 hub is tried and true, 2000 Hr TBO, only annual maintenance required, and the blades can be cleaned up here in the States for little cost. Only blades that could meet the 2000 Hr. TBO were considered. Flight performance was documented, not takeoff distance. Time to climb was tested only from 1000 feet to 10,000 MSL. (It was 30C and temps were starting to climb.) To keep the cost of the testing down, I stuck with only the 64 inch blade lengths and that screwed the Warp Drive guys a bit as when you cut the constant chord Warp, the total twist decreases, so “the twist is in the hub” as we say in the constant speed world. The Whirlwind has a fairly small visual angle of twist but its airfoil shape goes from a high lift section at the root to a flat thin airfoil at the tip. It is like comparing apples to oranges so I settled for just flying the prop blades head to head and doing analytical tests on blade length vs speed. See my paper on choosing the right propeller for your experimental on my website.

I found the following over all three propellers tests on 6 different days over two months but at nearly the same temperatures and pressure altitudes.

As you can see, the low altitude low speed runs are virtually identical. This made Airmasters point that the blade type in a low slow airplane does not differ the top end much. The constant speed prop improves the climb more than a fixed cruise prop and cruises faster than the fixed climb prop which is exactly what you want. What does become a factor is the spin up from idle as lighter blades spin up faster due to lower inertia, the residual thrust on  landing will vary due to blade and idle settings but the flat pitch decreases float distance, cruise will be as close to optimum for the blade and engine chosen, and finally subjective looks. Each aircraft design has a sweet spot. The Europa is very efficient at low speed cruise (110 KIAS), where the 80 HP 912 and fixed pitch prop is very efficient. Just not as fast as most of us would like to fly. However, for those of us who desire speed and long range, a blade that is 5-7 knots faster at 10,000 + feet density altitude is going to be very tantalizing. Provided it is reliable, easy to service and repair, doesn’t throw blades, and you can talk to someone who speaks your language at the factory, then it is worth the money. The 914 Europa can get to 10,000 MSL in about 12 minutes, use 1.5 gallons of gas from engine start to level off, and cruise at 143KTAS without using oxygen.  I can’t get to 160 knots without running at 5500 RPM at 15,000 MSL.  The airframe is capable of 170 KTAS at 10,000 feet if the engine can provide the power, and the prop can absorb it, so some will say why not fly there.

If I were a 912S owner with an Airmaster AP332 flying off lumpy grass pastures, I would use a Warp Drive blade as you can mow the grass with it on taxi out, turn around and take off. Your plane will look like a Chia Pet, but the prop will take it. A nicely painted blade with a clear coated nickel tape leading edge will be fine on clean hard surfaces or well maintained grass and because it has a more advanced profile will perform slightly better. Unfortunately, the clear coated leading edge tape will start to look a bit worn as the clear coat wears from sand, rain and bugs, so more touchup may be necessary. Since at low RPM and low speed the blade choice does not significantly change the speed of the aircraft, it may be prudent to stick with the blade one has and use the money to lower your aircrafts drag and improve the efficiency. However, if I were a 912S owner flying at higher density altitudes, using a Hacman leaning kit for better efficiency, or a 912iS owner and most of my cruising was above 10,000 foot density altitude, I would consider the Whirlwind for the slightly better speed I will get with a properly leaned engine. Landing at high density altitude may be improved also as the fine pitch stop of the Whirlwind is slightly shallower and you get a bit more braking from the prop without lowering your idle to unacceptable levels when confronted with shorter strips.

Finally, as the chart attached shows, the Whirlwind at a cruise climb of 90 Knots does climb very slightly faster than the Warp Drive. Takeoff roll didn’t seem to vary much, but the 90 and 75 knot climb rates and best angle of climb were very slightly better. If I was out in the high desert, I would look hard at a blade swap rather than considering buying a new propeller.

Attached above is my raw data from 2015 on the initial tests with my old carbs (yes I had to change carbs as one became quite scarred in the sleeve area and wouldn’t match the other). The carb change caused me to have to throw out my fuel flow data on my latest attempts at prop testing and the 15000 foot test with the Whirlwind was running about ½ inch low on MP when I tested the Whirlwind blades. With the new carbs I have different jets, EGTs are off as you would expect and due to work load I have not been able to retest with the new carbs.

Overall, I stand behind what I have said above.  I encourage comments. It will take me a while to get back to everyone as the shop is full of airplanes that are hard broke.

Bud Yerly


Sent from Mail for Windows 10

From: Remi Guerner (air.guerner(at)orange.fr)
Sent: Sunday, May 14, 2017 9:29 AM
To: europa-list(at)matronics.com (europa-list(at)matronics.com)
Subject: Re: Airmaster whirlwind blades


--> Europa-List message posted by: "Remi Guerner" <air.guerner(at)orange.fr>

Yes the article by Bud and Jim in EF 89 is interesting. Those Whirlwind blades are beautiful and the new ferrules are not protuding outside the spinner anymore as they do with the WarpDrive blades, adding drag without thrust.
The possibility to upgrade an existing Airmaster/WrapDrive prop with the new blades is very tempting.
However the article is disapointing regarding the compared cruise performances of the WD and WW blades. Both Bud and Jim say they see a few more knots at the same power setting. I have analyzed in details the figures shown in the charts for the Monowheel and here are my comments:
1. Some speed figures are very wide spread, sometimes 10 knots for the same conditions, probably because the air mass was not as stable enough during the testing. As we are looking for a few knots differences, that makes the comparison a little bit doubtful.
2. The tendency is a speed increase of 2 knots with the WW blades at altitudes up to 14000 ft.
3. The testing was done on the Rotax 914 only. I assume there would be some similar speed improvement also with the normally aspirated 912S.
3. Surprisingly at 17000 ft. figures show that the WW are slower than the WD for 3 out of the 4 power settings used for the test.
So to summarize, sorry Bud, I do not see the 5 knots increase you are talking about. Regarding the alleged reduced fuel flow with the WW blades at a given power setting at the same density altitude, this is just not possible. That is the law of physics. If the fuel flow is lower, that is due to either a lower power setting or an inacurate fuel flow meter, not to the better prop blades.
To conclude I pass the following message to Airmaster: with the Airmaster/WD blades on my Monowheel, 912 ULS, one on board, full fuel, I consistently get 140 kts TAS at full throttle, 5000 RPM at 8500ft density altitude. If I could get the proof that those WW blades would increase my cruise speed by 5 knots in those conditions, I would place an order immediately!
Remi Guerner
F-PGKL




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Remi Guerner



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PostPosted: Thu May 18, 2017 11:56 am    Post subject: Re: Airmaster whirlwind blades Reply with quote

Thank you Bud for all this detailed information. I am convinced that the Whirlwind blade is better than the WarpDrive by a few knots at cruise, even for a 912S Europa. I also believe the WW could be significantly improved with more twist. That would make the center portion of the propeller disk to produce some more thrust at cruise and therefore some more knots. Additionally, this would also improve cooling at ground idle.
It seems to me that most of these propeller blades have been designed mainly for the american LSA market were there is no motivation for increased cruise performances as the maximum speed is limited by regulation anyway.
For non LSA, faster is always better, so may be we should persuade Whirlwind to design a high twist blade ?
Remi


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