FW P-51 prop mod?

[rc-eflyer]

Might get to maiden the FW P-51 this weekend and I have a quick question on the prop. I've seen the "tie-rap mod" people are using on the FMS P-51 where you increase the pitch by slipping a tie-rap under the leading edges of the prop blades and wonder is this desirable/needed with the stock FW motor and ESC. I bought a spare set of blades and spinner/hub so I guess I could make those up with the mod to see for myself but I don't want to burn up the motor or ESC. Has anyone tried this???

Thanks
Steve

[WintrSol]

RE: FW P-51 prop mod?

Might get to maiden the FW P-51 this weekend and I have a quick question on the prop.  I've seen the "tie-rap mod" people are using on the FMS P-51 where you increase the pitch by slipping a tie-rap under the leading edges of the prop blades and wonder is this desirable/needed with the stock FW motor and ESC.  I bought a spare set of blades and spinner/hub so I guess I could make those up with the mod to see for myself but I don't want to burn up the motor or ESC. Has anyone tried this???

Thanks
Steve

Do you have a watt meter? If not, before you make changes to the power system, I recommend you get one. Without it, you're just putting you hand into a dark hole, which may contain poisonous snakes.

The mod for the FMS P-51 increases the pitch from 8" to about 10", which means the power consumption and current draw goes up about 25%; if your existing setup draws enough power that the mod will exceed the ratings, either those of the ESC or motor, you will probably burn it up. If you can perform the same mod, however, you can make a milder change, increasing the pitch until it just approaches the maximum ratings, if you think that's safe. You can get annealed wire at a hardware store in gauges from 28 to 22, with each size step increasing the speed and power some. I found that 28 gauge wire increases the pitch on the FMS prop from 8" to 9", and 22 gauge to 9.75, so you can choose more pitch speed, and maybe stay within the ratings. All this requires a wattmeter to verify, of course. If I were to use my prop with the 22AWG or zip tie mod, I would have to install a larger ESC, and hope the motor doesn't fail.

[Lon]

RE: FW P-51 prop mod?

Steve,

I've done the prop mod on my stock FW P-51.  Once you've done it, it is very hard to go back to the stock setup. By that, I mean the difference is quite significant. Your cruising speed is much better with less throttle. I'm not a speed demon, but I've always checked the motor and ESC after a flight, and have not detected any heat issues. I have 50+ flights logged with the prop mod, and no issues.  Late this last fall. I purchased a 85amp ESC, and started flying with 5s. Infact, yesteday, flew 5 batteries with her.  Two 5s flights, and three 4s.  So far, so good!! My recommendation is to fly no mod first few flights.  And then do the prop mod.  Your reaction will be "Oh yeaaa" and you probably won't go back to no mod. 

Lon

[rc-eflyer]

RE: FW P-51 prop mod?

Might get to maiden the FW P-51 this weekend and I have a quick question on the prop.  I've seen the "tie-rap mod" people are using on the FMS P-51 where you increase the pitch by slipping a tie-rap under the leading edges of the prop blades and wonder is this desirable/needed with the stock FW motor and ESC.  I bought a spare set of blades and spinner/hub so I guess I could make those up with the mod to see for myself but I don't want to burn up the motor or ESC. Has anyone tried this???

Thanks
Steve

Do you have a watt meter? If not, before you make changes to the power system, I recommend you get one. Without it, you're just putting you hand into a dark hole, which may contain poisonous snakes.

The mod for the FMS P-51 increases the pitch from 8" to about 10", which means the power consumption and current draw goes up about 25%; if your existing setup draws enough power that the mod will exceed the ratings, either those of the ESC or motor, you will probably burn it up. If you can perform the same mod, however, you can make a milder change, increasing the pitch until it just approaches the maximum ratings, if you think that's safe. You can get annealed wire at a hardware store in gauges from 28 to 22, with each size step increasing the speed and power some. I found that 28 gauge wire increases the pitch on the FMS prop from 8" to 9", and 22 gauge to 9.75, so you can choose more pitch speed, and maybe stay within the ratings. All this requires a wattmeter to verify, of course. If I were to use my prop with the 22AWG or zip tie mod, I would have to install a larger ESC, and hope the motor doesn't fail.

Yeah, I've got one. I hate to admit it, but I've had it since I built my first brushless motor using an old cdrom :rolleyes: . I was just looking for some "real world" experience which you have so graciously supplied, Thank You.

Steve
[hr]

Steve,

I've done the prop mod on my stock FW P-51.  Once you've done it, it is very hard to go back to the stock setup. By that, I mean the difference is quite significant. Your cruising speed is much better with less throttle. I'm not a speed demon, but I've always checked the motor and ESC after a flight, and have not detected any heat issues. I have 50+ flights logged with the prop mod, and no issues.  Late this last fall. I purchased a 85amp ESC, and started flying with 5s. Infact, yesteday, flew 5 batteries with her.  Two 5s flights, and three 4s.  So far, so good!! My recommendation is to fly no mod first few flights.  And then do the prop mod.  Your reaction will be "Oh yeaaa" and you probably won't go back to no mod. 

Lon

Bingo, that's exactly what I was looking for. I'm not really looking for blazing top speed, just want some reserve power if I need it and don't like flying around with the throttle maxed just to feel I'm not gonna fall out of the sky. I'll take your advice and fly it stock first but I think I'm gonna go ahead and make up my spare blades and hub with the mod. And yes, I'll check that setup with the wattmeter :angel: .

Thanks guys
Steve

[Grossman56]

RE: FW P-51 prop mod?

hey guys call me ignorant but just how exactly do you check it with a watt meter, step by step.  I'm not all that familiar with the ins and outs of using a watt meter, I have one, but that doesn't make me knowledgeable.

Grossman56 

[rc-eflyer]

RE: FW P-51 prop mod?

hey guys call me ignorant but just how exactly do you check it with a watt meter, step by step.  I'm not all that familiar with the ins and outs of using a watt meter, I have one, but that doesn't make me knowledgeable.

Grossman56 

Hey that's why we all come to these forums in the first place, I surey don't know it al but am glad to share what I do when possible.Not knowing exactly which one you have, it's kinda hard to do step by step but basically it just goes in line between your battery and ESC. If I remember correctly mine reads battery voltage, amps being drawn, and total milliamp hours used.  I think theres something else but can't remember off hand.  So, for instance if your wondering if you have a prop that might draw over your ESCs limit you just start advancing the throttle and watch the meter as you go.

Steve

PS: Just remembered the other reading.....WATTS....duh

[WintrSol]

RE: FW P-51 prop mod?

The procedure might be outlined in your instruction sheet, but many are in such poor English, you can just use the drawings as a reminder.

Put your model in a safe place, and tie it down; you don't want to see it go away at full power!
Connect the meter to your ESC first; if your receiver gets power from the ESC, make sure it is plugged in.
Turn on transmitter and set throttle to minimum, if your ESC is already 'trained' to the throttle range; if not, set up for the train procedure (see your ESC instruction sheet).
Plug meter into fully charged battery; your meter should now be on, and show battery Voltage, and the small current and Watts being drawn.
If you need to perform the throttle range train procedure, do it now.
If your meter has a peak hold function, enable it.
Advance the throttle to maximum, the same way you might for a take-off roll. You can slam it if you like, but I go for realistic power curves.
If the meter has peak hold, when the display on the meter stops changing, you can cut the throttle, and write down the numbers: Volts, Amps, and Watts.
If the meter has no peak hold, you will just have to try to spot the highest numbers as they flash by.
At this point, I usually reset the peak hold, so the meter shows power in real time, then advance the throttle, to see how the power holds up; also useful for discharging the battery back to storage level.

You can also do this with the motor on a mount, attached to a work bench, and a servo tester or receiver controlling the ESC. Just make sure the motor and ESC get plenty of cooling air.

[Grossman56]

RE: FW P-51 prop mod?

thanks guys, I'll print that out and it will go into my binder for useful information.  What meters do you guys have?

Grossman56

[rc-eflyer]

RE: FW P-51 prop mod?

Mine is quite old but I think it's still sold by Astro Flight, model 101. There are probably nicer ones now but there wasn't a whole lot of choice back then.

Steve

[WintrSol]

RE: FW P-51 prop mod?

thanks guys, I'll print that out and it will go into my binder for useful information.  What meters do you guys have?

Grossman56

I use the P1 by AEO RC. Small and relatively accurate, I keep it in the box I carry my batteries in, in case others at the field need to know.