Freewing 64mm F15

[Chuck52]

Hello. I'm somewhat new to edf jets and just getting back into the hobby after many years.I would like to upgrade the 5 blade fan to a 12 blade fan in my Freewing F15.Its 64mm.I would like to use a Freewing unit from Motion but I'm not sure which unit to choose.Still on a learning curve with 3s vs 4s and kv,etc. Can anyone recommend a Freewing 12 blade unit for the F15? I appreciate the help. Thank you.

[OV10]

Chuck.......Welcome to the Squawk,
Here is the most economical alternative which is used in the Freewing F/A-18 4S High Performance 64mm EDF Jet "Royal Maces" - PNP

https://www.motionrc.com/products/fr...6-3300kv-motor

[xviper]

Hello. I'm somewhat new to edf jets and just getting back into the hobby after many years.I would like to upgrade the 5 blade fan to a 12 blade fan in my Freewing F15.Its 64mm.I would like to use a Freewing unit from Motion but I'm not sure which unit to choose.Still on a learning curve with 3s vs 4s and kv,etc. Can anyone recommend a Freewing 12 blade unit for the F15? I appreciate the help. Thank you.

If I were in your position, I'd go to the MotionRC site and look up any Freewing 64mm EDF and take a look at what they suggest for "upgrades". There, you will something like this:
https://www.motionrc.com/products/fr...6-3500kv-motor
Also take note of how much amp draw it will have and see if your stock ESC will work for it. You might also need to upgrade that. Being a Freewing upgrade, you can be fairly certain that it will drop right in with little to no modifying.
Or you could get a motor like this:
https://www.motionrc.com/products/fr...utrunner-motor
And get just the 12-blade fan and install it into your stock shroud. Again, you may need a bigger ESC.
Basically, the relationship between cell count and KV is as follows: A LiPo cell can put out 4.2 volts at full charge. KV simply means rpm per volt. So, let's say you have a 4s battery (4-cell) ............................. 4.2V x 4 cells x 3800kv (eg.) = 63,840 rpm max. That's the max speed the fan will spin (in theory). Load, blade efficiency, airflow, battery efficiency, will all contribute to whether or not it will actually get up to that speed. Of course, the faster you spin the fan, the more thrust you can get out of it, to the point where the fan begins to "cavitate" and won't push any more. Also, higher blade count tend to be less efficient than lower blade count, but usually, the extra blades make up for the loss in efficiency.

Also, EDFs are power hogs. A "high C" rated LiPo is always an advantage and will give better performance, less sag during the flight. The Admiral Pros are good batteries for EDFs as are the HobbyKing Graphenes.

[WintrSol]

Also, be cautious routing the servo cables. I had to add extensions to reach my Rx, which I had mounted near the nose gear servo, because I couldn't find a way to fit it behind the battery. The battery shifted just enough on takeoff to disconnect the ailerons from the extension - slow roll into the ground. This model is really tight; if I ever get another, I'll either make a hatch to mount the receiver behind the battery, or punch a hole to route the cables around it.

[Chuck52]

Thanks to all for the replies. So a 3300kv motor on 4s will have enough thrust to propel the F15? When I was reading reviews regarding the 4000kv setup someone mentioned "puffing" batteries which I cant afford to do. I considered the 12 blade setup for more thrust of course but also because of the sound. I saw some you tube videos with the 12 blade and it did sound good. Would the 3300kv setup work with a 3s battery? What result should I expect? Thanks again.

[xviper]

I think 3s power would be somewhat anemic and would be a waste of this upgrade. Do the calculation I posted up before and you'll see how much decrease in max rpm there will be. It's significant. A "puffing" battery is not really an indication of the high kv of the motor. It's an indication of too low C rating on the battery. Start looking into better batteries or perhaps reconsider an upgrade if low C bats are all you have and all you're willing to ever have.

[Chuck52]

xviper2, your input has been very helpful. I see what you are saying on the 3s. So I think I will go with 4s and a high c rated battery. I don't mind buying new equipment, just don't want to buy the wrong stuff.

[xviper]

In case you weren't aware, know that when you go from 3s to 4s of the same mah capacity, the 4s will be much bigger in size. Measure the batteries that you currently use and weigh them. Use those measurements when you go to look for batteries. Most sellers will list dimensions and weight. You must be able to still balance the plane with the new gear if the battery is too heavy or too light, you will have to have enough room to move it around to maintain the same CG. MotionRCs own Admiral and Admiral Pro batteries are solid batteries for a reasonable price, as are the HobbyKing Graphenes. To look after your investment, try to cycle your new batteries on your charger for 3 to 4 cycles of "balance" charging and discharging before putting them into a plane. You can either use the "discharge" function but don't let them get below 3.8v per cell OR, you can use the "storage charge" function and they won't get below the danger threshold. I prefer "discharge" myself because it draws the juice out a bit faster and this may help season them and get them used to the demands of EDF duty.

[WintrSol]

Do you have the older F-15? The current V2 version has a 5100Kv motor for 3S, which provides about 17 ounces of thrust, on the ground. It sure pushed my F-15 into the air rapidly; it was much better than the first version FMS F-15 that my friend had. On 4S, the 3300Kv motor will turn fewer rpm (equal to 4400Kv on 3S), but the extra blades may make up for that. It will certainly sound better, and give more thrust than the V1 F-15.

As for discharging a 4S battery, it will be painfully slow on many chargers; I got two of these when I started using 4S batteries, and wouldn't be without them: http://www.myrcmart.com/rcx-3in1-bat...ng-p-4767.html

[xviper]

Do you have the older F-15? The current V2 version has a 5100Kv motor for 3S, which provides about 17 ounces of thrust, on the ground. It sure pushed my F-15 into the air rapidly; it was much better than the first version FMS F-15 that my friend had. On 4S, the 3300Kv motor will turn fewer rpm (equal to 4400Kv on 3S), but the extra blades may make up for that. It will certainly sound better, and give more thrust than the V1 F-15.

As for discharging a 4S battery, it will be painfully slow on many chargers; I got two of these when I started using 4S batteries, and wouldn't be without them: http://www.myrcmart.com/rcx-3in1-bat...ng-p-4767.html

Very good point about which version his F-15 is. Going to a 12-blade will require lowering the motor kv and going 4s to get better punch. Sound will improve, but it may be hard to better the push of a 5100kv, 3s.
That's a nice product for battery maintenance. You're right, even on "discharge" mode to 3v/cell (I stop it long before this), it can take many hours to drain a fully charged battery down to storage voltage.
The other possibility is to run the battery on low to medium throttle in the plane with a battery checker attached. Stop it at the right voltage. That should take minutes instead of hours. Just make sure to stay away from the prop (better to take it off) or not let anything get sucked into an EDF.

[Chuck52]

My F15 is the first version I believe. It was made by Freewing and came with a 5 blade fan,64mm size.Its totally stock,wanted to kick it up a notch.Im not so much a speed demon but I was really impressed with the 12 blade sound.I really like the plane, its the brown camo version.

[WintrSol]

I tried some math, to come up with model speed estimates. Assuming the fan blades are angled the same as the 5-blade fan (30 degrees), and the motor reaches about 75% of it's maximum rpm (V*Kv), I come up with the air moving about 100mph just behind the fan; because the outlet area is about 75% of the fan swept area, the outlet air speed would be higher than this, so the model may reach 100mph. Cool!

[gooniac33]

I have this plane. It is the newer FMS version but they are the same plane. I swapped out my fan for a 12 blade that I got off of ebay. It uses the exact same housing as the stock fan and drops right in. 3500kv, runs on 4s 2200 and sounds amazing!! Less than $30 for the fan with motor installed... can not beat that!! Here is a video of me flying is a week or so ago...

[gooniac33]