speedster 1919

My Feedback: (3)

OK BOYZ I finished all the prop testing for a 10 inch general size aimed at .40 to .52 sized engines. I was going to do 12" on a .61 but these test props get bloody expensive for sizes I may never use. Enjoy--- Randy
I'll post the first batch too.

Harry Lagman

Nice work Speedster. Thanks for posting!

BillS

ST .45 Italian made with torpedo muffler and exhaust deflector

10 x 7 APC
12,800
2900/3000 idle - If left idling it would drop to 2200 rpm without dropping dead.
4# 15 oz to 5# 2 oz thrust

10 x 7 MA Simitar
13,800
2900/3000 idle
5# 6 oz to 5# 9 oz thrust

10 x 7 MA old style
12,300
3200/3400 idle - seemed to need a higher idle than other props
5# 7 oz to 5# 8 oz thrust

The results were surprising and unexpected. Usually I expect APC to outperform old style MA. However in the 10 x7 size it appears that MA has a strong advantage. Similar data for an OS .46 shows the same trend, lower rpm but more thrust.

Bill

Jezmo

I have some airframes that APC works best on and others that MA excels on. From my point of view there doesn't appear to be a - one brand is the best - that sticks out. When I build a new plane I usually take a bunch of props with me and change them until I find the one that works best all around for that model. The experimenting with different props, fuels, plugs, etc. is what makes it exciting for me.

jaka

Hi!
Speedster ...what is it you are trying to prove????
Static rpm is worth nothing in real life except if you fly at zero speed...and possibly at hovering.

It's what a prop can perform in the air that counts and how the prop sounds! And it's here the 2 blade APC, RAM , Bolly and Graupner Cam -Prop will out perform a black MA prop. I admit hovever that the MA Scimitar is a fairly good prop, much better than the old black-tipped MA props.

Midrange rpm??? Why mid range rpm ...who is interested in mid range rpm performance???

speedster 1919

My Feedback: (3)

JAKA your a true blue Master Airscrew hater. I happen to like zero speed flying If you have a 5lb plane and want to go vertical a 4lb thrust prop would be wrong and a 5lb+ prop would be better. I choose 8,500 RPM because I felt that is the average flyer normal flying speed and since the WOT RPM's vary quite a bit, the 8,500 RPM would be an even playing field. You of all people to call 8,500 a mid range speed is a joke. You always seem to use a too big of prop in my opion and wind up with about 9,000 RPM. Heck 8,500 is almost you top speed. I set out to prove APC is not all that good and prove that a specific size stamped on a prop does not mean much in certain sizes. Also more than 2 blades are not that bad.
Jaka don't you owe us some big prop test???????

speedster 1919

My Feedback: (3)

Jaka --Here's my challenge to you. Do you own a .61 of some brand? Take a MAS 11x7.5 and beat it with another prop. List all props you tried. If you can't get one ( PM me ) and I will send you one. Tell me your faverite prop and I'll try to beat it with an MAS black prop. I have to admit the APC 12.25x3.75 is not allowed............Put up or shut up

jaka

Hi!
I'm a pylon racer since 27 years ago
I'll see what I can do...

blw

My Feedback: (3)

I've moved this since it belongs better here. This thread will not degrade into a grudge match with name calling, etc. Arguing aerodynamic principles will continue only if kept on a friendly level.

One thing to keep in mind- this is about static testing RPMs on the ground, and not under actual flying conditions. Everything changes once any model has begun flying.

Every type of model flies differently and RPMs vary accordingly.

gkamysz

My Feedback: (19)

This test proves no more than what the chart shows. The data is fine, but it doesn't prove how an airplane will fly. The results can't even be compared to another engine reasonably because other engine will have different HP/Torque curves and will not have similar results. This test needs to show how much power was required to turn the prop at the stated RPM. If you really want to compare .61 power wise I can blow any glow away in static thrust with a 1HP electric motor geared to turn a 24" prop. Why wouldn't one balance a prop prior to running it?

I like the MA Scimitar and have used them in my electrics before.

Testing props is a very complex matter. For models it's best just to test fly a few before choosing a prop. Interesting data, but I'll stick with my method of trying props on the model when I'm looking for top performance.

Jezmo

I am with you Greg. As I said above, I carry a bunch of props with me to the field and try em all before settling on the one that works best. The brand and size of prop I wind up with usually depends on whether I am setting up a pyon racer of just a sport flyer but even that isn't hard and fast. I own at least four different brands and I am most partial to the one that works best on whatever I am using it on at the moment. In other words I don't care what brand or color it is as long as it gets the job done. Git-R-Done.

jaka

Hi!
I'm with you too.
...And most of the time this is an APC...!

Flyboy Dave

My Feedback: (21)

....No one has yet to prove an APC sport prop (non pylon) is equal to, much less
superior to any other sport prop. The myth that APC props are head and shoulders
above the others is nothing more than a myth. There is no basis in fact to validate
the false claims of the APC aficionados in any way, shape, or form.

No one has yet to show that any APC prop, in any size, is better than the run
of the mill props....like Master Airscrews and Zingers. I wish I had a nickle for all
the times I read about how much better the APC props were, on these Forums.

My experience shows that....in an effort to provide less noise....the APC props have
come up with an over-pitch near the hub....which provides most of the thrust, while
their super thin tips keep noise down, but certainly fail in the thrust department. Most
performance experts know that maximum thrust/speed comes from the outer portions
(tips) of the props....where the prop speed is the greatest. This is not a secret. This
is where the APC props show their greatest defecientcy....at the tips.

FBD.

BillS

Magnum Pro .45

10 x 7 MA old - 11,800 3300 - 4# 5 oz.
10 x 7 MA Simitar - 13,000 3200 - 4# 11 oz.
10 x 7 APC - 12,300/400 3200 - 4# 11 oz.

11 x 6 MA old - 11,500 - 5# 7 to 8 oz.
11 x 6 APC - 11,600 3200 - 5# 10 oz.

Note the thrust difference between 10 x 7 and 11 x 6 props.

Note the rpm difference between 10 x 7 MA Simitar and the other 10 x 7 props.

Conclusion was that 11 x 6 props loaded this engine to heavy causing occasional rich mid throttle shutdown.

Bill

skiman762

Well all this testing is great if you fly a test stand
But in the real world I'll use what suits my style of flying

Good post Dave I emailed master airscrew lsat year about spinner size and the reply was as long as the outer one third is exposed
also a plane I fly with a 52 four stroke uses a apc 13x4 sport prop because it just can't turn a MA 13x4 my guess is the MA is bitting too much for the power I have
so I would have to say going by size numbers alone the apc has less bite

Flyboy Dave

My Feedback: (21)

.....any MAS prop over 11"....which means all the new 12 inchers are K series. These
are wide blade fourstroke props. These wide blade props are harder to turn than
"regular" props....APC props not included. An APC 12-6 will really lug down any engine.

Even a 12-6 K series MAS prop would be hard for a .52 FS to turn. A normal 12-6 prop
works OK for .52 and .60 fourstroke engines....I prefer the Zinger props if you want to
get anywhere near 9-10,000 RPM's static. A 12-6 MAS K series prop will lug down most
of the .52 FS engines, especially the Magnum engines. A 12-6 Zinger works well.

FBD.

Flyboy Dave

My Feedback: (21)

.....I am of course refering to the black plastic MAS props....

Master Airscrew makes many other nice props.

FBD.

gkamysz

My Feedback: (19)

Your visual computational fluid dynamics analysis was impressive. Boeing has a job lined up for you. It would save them billions in CFD software and computer hardware.

Flyboy Dave

My Feedback: (21)

....thank you, Greg....that was an astute observation on your part as well.

A precision eyeball is better than a team of engineers with slide rules anyday.

....an engineer is someone that says "that won't work".

....a mechanic is someone that says...."oh yeah, watch this".

FBD.

bdtsr

My Feedback: (5)

Technical term for a mechanic: "Field Engineer"
Definition of a "Field Engineer": A person who fixes or corrects the problems in design in "real life" created by the Engineer who sits behind a desk and fails to listen to the Field Engineers.
My son is planning on the Engineering field for a carrer. I hope he learns from "real life" and applies it to his engineering skills.

All planes, engines and props are different. What works for one may not work for others. I have had less problems balancing APC props than Zinger props. The last Zingers (11X8P) I bought had several that had hub balancing problems. Threw 2 in the trash. But the Zinger 11X8 pushers really make my Balsa USA Enforcer move out. I think the black MAS props are the best for training as the are tougher than nails and work fairly well. Anyone that takes the time to test anything as objectively as possible and post their results is ok in my book. To those that take the time to do this, please keep at it. There may just be someone who might benefit from it including me.

gkamysz

My Feedback: (19)

This occurs because there is no communication between the shop/field and the engineers. The field guys like to feel better than the engineers, because they have hands on experience. It also ensures job security. If there was communication between the two, eventually all issues would be solved in the office and the field guys wouldn't have any work to do. Now in some fields this is impossible, but in the mechanical realm it comes very close in a well organized firm. Obviously when the super asks why things are constantly reworked and the answer is that the engineer didn't design it right and wouldn't incorporate the changes the field engineer recommended, somebody is going to get fired.

In my opinion, most model props are only designed and not tested to meet their intended application. This is fine because they are cheap and 99% of the customers can't tell the difference, or even know how to verify claims. Some props aren't even designed other than a rough design, and they still work.

If you want to do prop test, look up a real prop chart by a major aircraft prop manufacturer and see what they do. Applying that to a model prop is way beyond most modelers understanding. So a basic test like above is VALID, however it provides little information about how it works in real life applications, other than the specific situation it was tested in. Taking the time to do such a test is certainly honorable, but to me such a test has little useful information as the typical prop characteristics can't be determined from the data collected.

blw

My Feedback: (3)

Having worked as a full scale pilot for 15 years, and raised by my dad who had his A&P for a major airline and his pilots license, and knowing aeronautical engineers I've never heard any of this stuff about engineers. I hung around the crew chiefs and mechanics most of my years flying, and I know they never said anything like that about engineers. I've heard positive things said all the time.

Below are two links to prop manufacturers. One goes into detail about prop design and applications. The other doesn't go as much into it. I checked the Master Airscrew, Xoar, Graupner, and Mejzlik sites for any info on their research, and found none.

http://www.apcprop.com/Engineering/e...ng_design.html
http://www.xoarintl.com/productionProcess.html

We need to get back on topic.

skiman762

Well I worked 23 years in the USAF in B-52Gand H and KC134Q,Aand R model maintanence and attended many product improvement workshops at Tinker and bringing the concerns of many of my peers to engineers not one of then was ever put to action and I'm talking things like access panels with 6 quick release fastner that broke every 2 or 3 times they were opened we wanted plain ole 10-32 screws it would add a whopping 30 secs to the task and save the 1-2 hour it took sheet metal shop to fix the broken quick release fastners but they turned it down so go figure
Also we had some really dumb mods sent down to us that we were never even asked our input on so there ya go
remember the grunt with the tool box only know the way it is, not the way he thinks it should be

speedster 1919

My Feedback: (3)

blw Did you even go to Master Airscrew ? I consider this good advice for props and they make it simple............
http://00e2fac.netsolstores.com/imag...ler%20info.pdf

blw

My Feedback: (3)

Speedster-

Yes, I checked their site for design and research info.