Hi Guys,

I have been using an AeroNaut CF 10 x 6 prop. It flys my 57 oz. P-40 very well at about 85% power. But, it is flying  faster than the other planes (glow) at our field. A little under 5 sec laps on 60' eye to eye lines.

The plane flies great. Plenty of line tension everywhere. It will do an unlimited amount of overhead eights (I stopped at 8, my neck got tired ;-) But, I would like to be able to fly slower like the other planes.

When I turn down the power, I lose some of the line tension overhead that I have come to love. The LOs and CG seem to be in a good location according to local experts.

A Zinger Pro 11 x 6 gave awesome power (of course same speed) but it really sucked down the battery. On the 10 x 6 I use approx. 2,700 mAh per 6min 30 sec flights. With the 11 x 6 I used 3,900 mAh from my TP 4,200 4S2P Battery. The Battery and Motor were both hotter than normal. (da! ;-)

Would a 11 x 5 wood prop work better? How about the Bolly 11 x 4 props used on the Aero Tiger glow engines

What props are you all using? Please include brand when you answer, along with the size. Also, please mention if you had to modify the prop to get the size you use.

I have just ordered a Prather (SP?) Pitch gauge so I can modify props. I have never done this before, but I hear this is what guys are doing to get the right prop for our electric planes.

Thanks in advance for your help on this.

Quote of the day:

    "Without ammunition, the USAF would be just another expensive flying club."

Hi Linhart,

I watched your beautiful Bearcat fly on one of Windy's videos. It looks like a perfect setup. Nice flying too! :-)

Thanks for the input. I have to assume that the Electric props have a lot less drag, and load, than the regular props made for glow. After my experience with the Zinger Pro 11 x 6, I would think a 12 x 6 Zinger would melt my motor and Battery! ;-)

I'm going to try the APC Electric 11 x 5.5, this is what my LHS had.  I will order some different props and start experimenting. I did not want to try different ones until I got the plane trimmed out. Now, with about 25 flights on it, it is time to try some new props.

RE: Pitch gauge. I ordered one from my LHS, Covina Hobbies in West Covina CA. (near our flying field in the  LA area). I always try them 1st. Your LHS may be able to do the same? But if not, Brodak carries them.

    http://www.brodak.com/shop_search.php?productsearch=pitch+gauge 

Thanks again for your help. I hope others pitch in here so that we can all learn more about props from each other. :-)

Hi Guys,

I have been using an AeroNaut CF 10 x 6 prop. It flys my 57 oz. P-40 very well at about 85% power. But, it is flying  faster than the other planes (glow) at our field. A little under 5 sec laps on 60' eye to eye lines.

The plane flies great. Plenty of line tension everywhere. It will do an unlimited amount of overhead eights (I stopped at 8, my neck got tired ;-) But, I would like to be able to fly slower like the other planes.

When I turn down the power, I lose some of the line tension overhead that I have come to love. The LOs and CG seem to be in a good location according to local experts.

A Zinger Pro 11 x 6 gave awesome power (of course same speed) but it really sucked down the battery. On the 10 x 6 I use approx. 2,700 mAh per 6min 30 sec flights. With the 11 x 6 I used 3,900 mAh from my TP 4,200 4S2P Battery. The Battery and Motor were both hotter than normal. (da! ;-)

Would a 11 x 5 wood prop work better? How about the Bolly 11 x 4 props used on the Aero Tiger glow engines

What props are you all using? Please include brand when you answer, along with the size. Also, please mention if you had to modify the prop to get the size you use.

I have just ordered a Prather (SP?) Pitch gauge so I can modify props. I have never done this before, but I hear this is what guys are doing to get the right prop for our electric planes.

Thanks in advance for your help on this.

Quote of the day:

    "Without ammunition, the USAF would be just another expensive flying club."

Hi Rudy

I can tell you the most common props I sell for that motor
3 blade Bolly 11 x 4n  and  12x4 n
12 x 4 cf Bolly
11 x 6 Cf bolly,  all these  props are very easy to turn
Bob Hunt uses  a  prop That is almost exactly the same as the 11 x 4 3 blade, he has both  Bollys and Bill Lees thin 3 blades, so does several other people.
there is also a host of APC props that can be used also 12 x 3.75 is used too.

Regards
Randy

PS  I also have  pitch gauges in stock

www.aeroproduct.net

Hi Rudy,
   A friend of mine is trimming an ARF Vector (53oz ready to fly) with an AXI 2826/10. The only props used so far have been the APC-E 11x5.5. I have been doing the pitching for him and we are down to 4.5" pitch on 62' lines eyelet to eyelet. The result was lap times in the 4.7sec range. I just repitched another 11x5.5 to 11x4 and he will give it a shot in the next week or so.
   In short the props are worth every penny being in the $4-5 range. For most fliers the gains found in carbon props are not worth the extra $30 plus dollars.     
   Good luck with your setup!!

Hi Mike,

Thanks for the good news. I'm glad to hear the Electric APC prop performs so well. As soon as I receive my pitch gauge I will try and learn how to "bend, twist, fold, and mildly mutilate" my APC prop to get the pitch I need. ........ When I receive my "Hi Zoot" CF 11 x 4 3B prop from Randy, I will try to carefully twist it too.

Mike, (and anyone else) Please let me know if my understanding of how to modify props is correct.  TIA

After reading all I could easily find on twisting props, here is my understanding of how it is done:

How the Expersts do it: (.01% of PAMPA members)

They use the very high tech welding torch, the same one that is made for NASA. They apply an exact amount of heat (1,287 degrees, +/- 2 degrees) for 5 nano seconds every 1/16" along the prop, twisting, then measuring to the nearest 1/100th of a degree at each 1/16" station.  Then they heat cure the prop in a magic kiln for at least 18 months. ..... BTW: Not having this "High Zoot" skill is the ONLY reason most of us will never win the Nats!!

For the rest of us (99.99%):

APC props:     Boil some water, take it off the stove, throw in your prop for several(?) min., take it out and, if going low to higher pitch, twist it near the hub (where the airfoil starts) until your pitch gauge says your where you want to be. If going from a high to lower pitch then same as above with one additional (optional) step:  then add back in a little MORE pitch out at the tips (a few 10ths). (Thanks Leonard :-)

CF Props:   Use a Monokote type heat gun instead of the boiling water, (this will work on APC props too). Heat the CF prop until you can feel the threads move when you twist the prop, but not so hot that you weaken the molecular bond within the CF material. Then do same as above.

Aprox. 50% of the props thrust is generated in the "outer" 30% of the props dia. So we may want to spend our time measuring/twisting accordingly! ;-)

Thanks again for your answer, and all the great ground work you did to make Elec. CL flying easier for the rest of us. :-)

Hi Rudy,
   A friend of mine is trimming an ARF Vector (53oz ready to fly) with an AXI 2826/10. The only props used so far have been the APC-E 11x5.5. I have been doing the pitching for him and we are down to 4.5" pitch on 62' lines eyelet to eyelet. The result was lap times in the 4.7sec range. I just repitched another 11x5.5 to 11x4 and he will give it a shot in the next week or so.
   In short the props are worth every penny being in the $4-5 range. For most fliers the gains found in carbon props are not worth the extra $30 plus dollars.     
   Good luck with your setup!!

Hi Rudy,
The JMP bumps the throttle up a tiny bit at mid flight, right? I haven't fiddled with one myself. Just set it so that the amount of the "bump" is zero. A constant throttle setting all flight long will correspond to a constant RPM all flight long. If you actually want to fly faster at the end of the flight, then you can do that too, but Bob gave up on it once already. If you did add a few RPM I can tell you that all you will need is maybe 4 or 5 microseconds more throttle pulse time. As a starting point, I can tell you that about 1380 microseconds output pulse yields 10,000 RPM on an AXI 2826/10 with the Castle heli governor "high" range selected. The low range tops out at 9,000 RPM with a normal full throttle (2000 microsecond) pulse. For those not familiar with the output pulse format, the ESC is controlled by the width of a pulse that comes out of the timer (or RC receiver) and is repeated every 20th to 50th of a second. 1000 microseconds pulse duration is always idle/stop. Something close to 2000 microseconds (usually anything over 1800) gives full throttle. In governor mode, anything under 1200 or so is stop, then from 1300 to about 1900 the pulse width commands a variable RPM. a 6" pitch at 10,000 RPM is awful good as a starting point. The governor will add throttle internally as the load increases at the top of the circle, allowing you to fly slower. As always, diameter is king, until all those spiral/GP/torque effects make trimming stoopid. (sic) That's why Bob runs a 11.5 X 5.5 three blader. Now all I have to do design a counter-rotator gearbox that weighs nothing. then we can just keep adding diameter! I digress.

Thanks for the kind words,
Dean

Rudy,

Hi Guys,

I have been using an AeroNaut CF 10 x 6 prop. It flys my 57 oz. P-40 very well at about 85% power. But, it is flying  faster than the other planes (glow) at our field. A little under 5 sec laps on 60' eye to eye lines.

The plane flies great. Plenty of line tension everywhere. It will do an unlimited amount of overhead eights (I stopped at 8, my neck got tired ;-) But, I would like to be able to fly slower like the other planes.

A Zinger Pro 11 x 6 gave awesome power (of course same speed) but it really sucked down the battery. On the 10 x 6 I use approx. 2,700 mAh per 6min 30 sec flights. With the 11 x 6 I used 3,900 mAh from my TP 4,200 4S2P Battery. The Battery and Motor were both hotter than normal. (da! ;-)

Would a 11 x 5 wood prop work better? How about the Bolly 11 x 4 props used on the Aero Tiger glow engines

I would like to try to answer this question a little bit differently. First there is no particularly good reason for your airplane to fly at the speed of any other persons plane. Different weights will inevitably necessitate faster or slower lap times. You say that your plane weighs 57 ounces (dry). That is (not being cruel) a fairly high weight for a plane that size. To make a plane of 57 ounces perform you will need to provide it with more airspeed than you are doing (on 60' lines) even though it "seems" you are flying very fast. (It seems fast since your lines are too short)

Listen to what Dean is telling you about absorbing horsepower from your system. You would be much better off to stick with the larger prop and simply lengthen your lines to around 63 - 65 feet and maintain the same lap speed. This will increase your airspeed substantially. Your plane will be much happier! Depending on how much you lengthen your lines, you should begin to feel more comfortable with the plane even at the same lap speed as before since all the segments of each manouevre are now longer. As long as the plane remains highly manoeuvreable, you will then be able to dial the motor back (or go to a lower pitch) a bit and slow your lap times down.

As a general comment, never try to make your plane fly like someone else's. We each have a very different style and physical capabilities. Develop a style based on your own person attributes and you will move forward much faster.

You mentioned that the 11x6 Zinger made the plane fly with awesome power. Thats what we want!!! (Although drawing the battery down to 92% is too much.) For the Thunder Power Pro Lites, draw them down to no more than 80% (3360 mah) for best performance and cycle life. Now you just need to get your line lengths set up correctly.

Now as to which props to use I would suggest that you try anything that is light and has a lot of blade area. Our testing is currently pointing to the use of Master Airscrew Wood 2 blade props (sport model) as among the very best. Looking at your amp draw for the Zinger 11x6, I would suggest a Master Airscrew 11x6 cut down to 10.5x6 as a good starting point.

As to wether you should fly in governor mode or not, IMHO there is only one answer. You need to fly in governor mode. Our testing and Bob's (I think he would agree) point to not needing to ramp up the power during a flight. Everything you are currently doing or contemplating is in effect trying to duplicate what governor mode will do for  you automatically. Generally once an ESC is set in governor mode it will stay in that mode. Read your ESC's instructions to see what you need to do to make governor mode active. To fly in governor mode you will need to have a certain amount of "headroom" (capacity) in the battery to enable the ESC to keep you flying at your chosen rpm and not fall off. You can not fly at anywhere near full throttle (full throttle is by definition the point where governor mode can no longer function as there will always be less power available in every following second than the last) in governor mode and stay there. As I have said before, this is where doing A LOT OF HOMEWORK will really pay off! 

Kim.

Hi Phil C., and Kim,

Thanks for the additional info., it helps! :-)

I will add 2' to my lines. I agree, this should help get the slower visual pace I like. I think my batteries and or motor is getting broken in? I get the following results while only using about 65% of the battery power (2,740 mAh). My lap times are now 4.7 with my 60.7' eye to eye lines (this is really = to a 66' radius when you include are handle lines, + arm, + plane leadouts, + 1/2 wing span). This then actually works out to 60.2 MPH according to the little SS I made up. I'm turning my 10 x 6 prop at 11,400 RPM. I think that I could turn the TH up a little and fly combat with Rich Lopez and the guys in the circle next to me! ;-)

I think this is what you both have suggested; .... longer lines to give the "relative" feeling of flying slower, .... more prop dia to generate more thrust, ....... pitch to set lap times that give good control with the pace that makes me happy. :-) ..... All the while keeping the power draw from the battery at approx. 80% (about 3,360 mAh). ..... And, using the Helli governor mode. ....... With a TH setting that will give all of the above, plus allowing enough head room for the battery to have the reserves needed to help the governor keep a constant RPM, even during peak demand periods, throughout the stunt pattern.

I hope this summary is what you were saying? My plan is to follow all your suggestions so my plane can carry me to winning the Nats in 2007!!! :-)   (just kidding, Brett is safe until at least 2020 ;-)

A few comments about A/C weight:    (thanks Kim for being sensitive to my weight problem :-)

My Brodak ARF P-40 is now "only" ;-),  56 oz. I took the Aluminum spinner off. Amazingly enough, from a wing loading perspective, it is almost the same as my Nobler. The P40 @ 56 oz, 560 sq. in. = 14.4 oz/sq ft. The ARF Nobler is 45 oz + 4 oz fuel = 49 oz @ 500 sq in = 14.1 oz/ sq ft. This is pretty close. I think the power loading is close also. IMHO: My AXI is at least 14% more powerful than the OS .40 4/2 in the Nobler. This makes the power loading about the same.

BTW, I think one could easily take 2 to 4 oz of weight off of the ARF P-40. I built it completely stock as an electric demo for our club members. I wanted to show that an electric set up could be put into any existing CL plane that was now using IC power. And with NO mods needed. Even at this MAX weight of 56 oz., the plane flys very well. I have approx. 30 flights on it now. It has flown in dead calm many times, and in winds. It has never lacked for power or line tension in any maneuver. My flying skills are NOT good enough to push the plane beyond its limits, but I think it would be fine for 95% of the CL flyer's out there. :-)

I look forward to using all your suggestions and getting to fly a relatively slower pattern that will fit my style of flying. ...... Thanks again for all your excellent help, and the generous sharing of your time and knowledge. :-)