3 Blade props
 

I notice the 3 blade props advertised as the poor mans Contra. What is the story on them.

Has anyone tried one ?

Thanks

Falcon is suppose to release carbon 3 blade props for pattern.

This is from F3A Unlimited:
Oktober 3, 2014 Just listed as new products are 85mm or 3 3/8 inch and 89mm or 3.5 inch spinners from Falcon for both 2 bladed and 3 bladed propellers.
3 bladed props are becoming the hottest items we sell. Dubbed by many top fliers as the "Poor Man's Contra" with props from PT Model, and Mejzilk in stock and some time late this year 3 sizes from Falcon.
Source: https://m.facebook.com/f3aunlimited/...ype=1&refid=17
I have not found any Falcon 3 bladed props at F3A Unlimited, but they have 3 blade prop from SDC Composites and PT Model.

When Falcon has their 3 blade carbon props on the market I think I will try one. I use their 20.5 x 14.5 carbon V2 electric prop 2 blade today in my MythoS Pro (with Hacker Q80-14XS).

/Bo

A 3B prop works very well if you have a slow flying style. It is easier to control the power and speed. For a fast and big flying style you will use a lot of mAh compared to a 2B.


I used to fly 3B with a Pletty Advance powered Wind S Pro. Due to the low drag model this combination worked really well. My favourite prop was the PT Model 20x13 3B. Ulsamers 20x13 3B was to small/ didn't have enough trust. Mejzlik 20x13 3B used a lot of mAh if i wasn't careful with the throttle.


I have sold the Wind and prefer 2B on my other models.


Regards,
Henning

We currently have 3 bladed props for 3 manufacturers. SDC, Mejzlik, and PT Model.
5 Options in all.
Falcon props will be available by the spring in either 2 or 3 sizes. The 3 bladed props have become very popular.
http://www.f3aunlimited.com/3-bladed...iber-propeller
Mike

I was just wondering almost 300 views and only 2 comments on them. I need more info before a try.

I can tell you that the largest sales on the 3 bladed props has been to Central and South America. And Israel has a lot of fliers doing 3 bladed props.
If you find pictures from the recent Championships held in Columbia you'll see a lot of 3 Bladed props.
The Mejzlik 20x13 is the most popular. The SDC is almost identical but very new to the market. The SDC is as well made if not better than any prop ever made for F3A. They are very stiff and very light and the finish is near perfect.
Mike

I hope we can get more feedback , too. I believe that my Griffin, a low drag model(IMO), could benefit from the braking .

I was going to start a new thread but might as well just pick it up here.

My question is this:

What is the best way to determine 3-bladed prop size coming from 2-bladed? It's not very cheap to really experiment with the carbon props so I'm wondering if there is a way to truly give a good comparison between them. For example, if I'm running a 21x14 2-bladed prop, how do I figure what size 3-bladed I should run? Do you reduce diameter by one and pitch by one? So, does a 21x14 2-bladed equal a 20x13 3-bladed? I realize how the prop performs on a specific airplane will vary but if one likes the way a 2-bladed prop runs, how does one figure out how to replicate that with 3 blades and gain the braking without running a $100 per prop experiment?

Thanks!

eCalc can give you a good idea of the differences between 2 and 3 blade props with respect to power, pitch speed, rpm, thrust, etc

(deleted post - I was going to say something about general guidelines for changing number of airfoils, but then realized that we use things a little differently in F3A which may go against the normal approach. Generally you get more thrust and drag from an added airfoil, so you reduce diameter to balance the power load and increase pitch to compensate the drag and loss of RPM/air speed. However we operate in a unique power curve and manage throttle a little differently, so the general rules might not give the best F3A results).

I have tried a few of the three blades available. I have until recently always seem to end up back to the two blade props, so I think its very much a matter of preference. I have found that the Mezjlik 20x13 didn't have the performance that I was used to with the 2 blade, and the battery consumption was higher than with the 2 blade. The Falcon 20x12.5 was better regarding the battery consumption, but the speed was just a little too slow to be acceptable across a broad range of conditions.

I recently tried the Falcon 19.5x13 3B, and I think this one may be a winner. The battery consumption seems to be similar to my favourite 2 blade (Falcon 21.5x13), however I think the constant speed appearance of the flight is better and the natural braking of the prop is better. Vertical performance is still good as well.

All that said, its still a lot based on flying style and your model, so I think you have to experiment, which can cost a few bucks, but I would recommend the Falcon 19.5x13 3b as at least a good place to start from.

Chad

Chad,

Thank you very much for the suggestion. As you know, I have the prototype Contra Allure and have really enjoyed both the airplane and Brenner's Contra unit. The consistency in speed and power is quite nice. I have my Allure coming on the first shipment and have debated exactly what to do for power on this plane. Bryan has decided to sell me the prototype (it took awhile but finally, he agreed) so I will have two of the same plane. The cost of having 2 complete Contra units is not something that I can afford. I've been thinking about trying a 3-blade prop on my production Allure to see if I could get it close to the way the prototype behaves hence the question. Either way, the Allure will fly at a good speed due to its size but I thought maybe a 3-blade solution may be the answer.

Joe, I appreciate your input as well as ltc for the eCalc reminder. Thanks guys!

Scott

Scott,

You said, "the Allure will fly at a good speed", do you mean fast ?

Have you considered a 3 blade Vario-prop?

See: http://www.ramoser.de/home_e/variopr...rioprop_e.html


Jer

Hi Jer,

The Allure flies well at whatever speed I've tried with the Contra. Mark Hunt had this plane before I did and had the Neu motor w/ single 2-blade prop before Bryan and I (really Bryan did all the work and I just got to be the pilot) converted it to the Contra. Mark said that it flew great at that "speed" as well. I guess what I was trying to say is that the Allure is a huge plane and has plenty of drag built in to the airframe. Although the Contra unit lets the airplane fly very consistent speeds, the inherent drag of the plane will also help so. if I can get similar performance out of a 3-blade prop, I would be interested to try it. I've watched Brett and Bryan fly the glow prototype and its speed is fine. Honestly, I haven't tried a 3-bladed prop on anything since the old Conquest 120 days and certainly not on an electric F3A plane. The props are being billed as the "poor man's Contra". It would be nice to have similar performance between both of my Allures without the expense of another Contra which I simply can't do.

I have not considered the Vario prior to your post. I will look into them. I appreciate your time.

Regards,
Scott

JB-Hobbies here in the USA is (becoming) a dealer for Varioprops.
It makes it a bit easier than buying them direct from overseas.
However, Varioprops are anything but lightweight!

Chad,

Looks like I picked the right prop...Falcon 19.5x13 3B. I have only 3 flights (very windy flights) so far, but battery consumption is normal and pulling through heavy wind didn't seem to be an issue, even in the opposite snaps uphill. Waiting for calm weather to get more flights and really determine how improved the speed control and downline braking is.

http://www.rcuniverse.com/forum/atta...mentid=2072543


-mark

Hi Scott,

I think that the 19.5x13 is certainly worth a try for you, on the few flights I have had so far (winter you know!) I really like its speed presentation. So I think if you are going for a similar presentation to the contra it will certainly be closer than most of the 2 blades that I have been flying with, which are generally a little faster, especially on the downhill bits.

Good choice Mark! Glad to know I am not alone with my thoughts :)

Had 20 flights on Falcon 19.5x13 3-blade so far, really like its smooth performance. One new AMA master sequence usage is 3600-3700mAh, no difference from the Falcon 21x13.5 V2 2-blade.

http://www.rcuniverse.com/forum/atta...mentid=2073243

I have 4-5 flights on the falcon 19.5x13 3B and so far am really happy with it. I wouldn't say its a drastic difference between the braking of a good 2 blade but more constant speed feel through maneuvers. I'm still learning to fly with it, but so far so good. Flying through the advanced sequence burns approximately 2850-3000mah.

What motor are you using ? Was there any difference in amp draw compared to the 2 blade ?
Thanks

Motor is a hacker Q-80 14XS, as far as amp draw is concerned I never actually put it on a watt meter to be exact. But I can tell you that the motor comes down approximately the same temperature. Now for an FAI sequence I would expect a noticeable difference because of the heavier throttle requirements to fly those sequences. But as far as the AMA Advanced sequence is concerned the mah usage and motor temps are pretty close. The 3B uses just a bit more mah overall but nothing really substantial, 150-200mah.

Sounds Good, I want to try it on a Hacker A60 7S in a Nuance . I think it might work, I only fly Intermediate so not very demanding.
Did you notice any trim changes with it ?
Thanks Kirk

to be 100% honest I'd have to switch back to the two blade again to remember if I did have some trim changes or not.

If anyone wants to try a 3 blade setup I have a 19.5x13 3B and falcon 3B 80mm spinner I need to sell. Going contra!