FT What Did You Do RC Today : Caution Offtopic At All Times

[Grifflyer]

I am worked on my 70mm EDF i am scratch building and my four engine cargo plane that i am building. Quick question, anyone know a good propeller/motor combo that will make a (scratch built) motor glider with a 22" fusealage and a 30" wing really fast, like REALLY FAST. Also, it would be fantastic if it was farely cheap.

For the motor glider you could just use the F pack motor a 30 amp esc and a 4s battery that'll get you going pretty quick.

 

[IcedStorm777]

I will be making a wing that at the root is 10 inches wide (chord) and the leading edge will taper back to 3 cm at the tip. Sorry, i made that unclear. I will be using a wing shaped device, sticking another wing shaped device on top of it that is about half the chord of the wing. I will then sand the leading edge.

 

[IcedStorm777]

For the motor glider you could just use the F pack motor a 30 amp esc and a 4s battery that'll get you going pretty quick.

Cool thank you!

 

[Grifflyer]

One more question, i am making two wings that have are tapered on just the leading edge, this is for the 70mm EDF i am making. To build my wings i almost always use the ExperimentalAirlines way which is great for straight wings but doesn't really work for tapered. Could i use a KFM2 wing on this 70m EDF? if not is there another way anyone knows of for making tapered airfoils?

Yes that should work, it's worked well for me on my grunjet the only thing I can suggest is you might want a spar other than foam (wood or carbon fiber) because if you just laminate a couple pieces of foam I don't think it will be strong enough to sustain the weights of a 70mm EDF jet.

 

[IcedStorm777]

Cool i am planning on doing a KFM 4 airfoil (so that it can go inverted well) Using three separate pieces of foam and then sanding it down to an airfoil shape. I will be using a 36" wooden home depot ruler as my spar.

 

[IcedStorm777]

Actually, ca't decide between KFM4 and KFM2 airfoils, any insight? I would love for it to be able to do inverted decently but i realized a KFM4 airfoil is the same on top and bottom, so HOW DOES IT PRODUCE LIFT! If it is symmetrical it is even on top and bottom which means no pressure differential. What would ya'll recommend? KFM2 or KFM4?

 

[Hai-Lee]

Actually, ca't decide between KFM4 and KFM2 airfoils, any insight? I would love for it to be able to do inverted decently but i realized a KFM4 airfoil is the same on top and bottom, so HOW DOES IT PRODUCE LIFT! If it is symmetrical it is even on top and bottom which means no pressure differential. What would ya'll recommend? KFM2 or KFM4?

The lift is generated by the difference in the distance the air must travel when crossing the top of the wing Vs the bottom of the wing. To achieve a difference in difference the wing needs an Angle of Attack (AoA). As a plank, Kfm2, Kfm4, or any other wing design can achieve an angle of attack then lift will be realised. The wing efficiency, (lift Vs Drag ratio), may vary considerably but almost any physical arrangement will fly.

As for KFM2 or KFM4 the choice is totally yours. KFM 4 will be stronger and able to produce more lift but obviously it will be heavier. One little trick to help keep the weight down is to remove one layer of the paper between the FB layers so that the join only has a single layer of paper with foam on both sides. An added advantage is often the glue will seep through the paper and actually glue both foam layers to the foam and so de-lamination fears long term disappear.

Just a few thoughts!

have fun!

 

[IcedStorm777]

Another question question that i thought up. So there are different size motors which also have different KV, but there are some high power lifting motors that have super low KV, how is this possible? The KV determines how fast the shaft rotates right? So a higher KV motor=prop spinning faster=more thrust, right? Why do some high power motors have low KV ratings?

P.S. (Sorry for all the questions, as i am 14 and barely know anything i ask a ton of questions, if i am ever clogging up the thread just DM me and tell me to be quiet.)

Thanks!

 

[Hai-Lee]

I will try to put this simply.

The higher Kv motors generally use smaller propellers. Low Kv motors use Large diameter propeller. Motor speed is only half of the story.

The second in the POWER story is the motor TORQUE, (the power available to push the motor up to speed). Most high Kv motors have relatively low torque capabilities whereas low KV motors generally have higher torque capabilities.

The third part to consider is the applied or battery voltage The higher the voltage used the faster the motor will rotate but also additional current or torque will occur.

The final thing to consider is the windings of the motor and the "Ampere turns" the motor can provide without damage. The ampere turns are directly related to the available motor torque and to the heat dissipated!

I hope that helps a little!

have fun!

 

[Bricks]

I found these pics from earller this year I did a good job. when inverted down is up and up is expensive,

 

[d8veh]

Another question question that i thought up. So there are different size motors which also have different KV, but there are some high power lifting motors that have super low KV, how is this possible? The KV determines how fast the shaft rotates right? So a higher KV motor=prop spinning faster=more thrust, right? Why do some high power motors have low KV ratings?

P.S. (Sorry for all the questions, as i am 14 and barely know anything i ask a ton of questions, if i am ever clogging up the thread just DM me and tell me to be quiet.)

Thanks!

A 1000Kv motor with a 3 cell battery will run at exactly the same no load speed as a 1500Kv one with a 2 cell battery. The propeller, Kv and battery all need to be considered together when it comes to selection.

 

[IcedStorm777]

What would be a good propeller to put on this, i am using a 25a speed controller and this motor


https://www.amazon.com/dp/B07FMCHLFC/?tag=lstir-20

I am using this for a snow skimmer with a 850-3200 3s battery (depending on what balances the CG right.

 

[SlingShot]

Finally repaired my Mini Cruiser. It had a bad maiden months ago that annoyed me. Later, one of the cats got loose in my shop/studio and did some hanger rash damage to a wing. Ready for action now

Also refortified the skewer holes on the Kraken and cleaned up some minor dings from the high weeds.

 

[Paracodespoder]

Worked on painting this.

Not completely finished painting yet but this is about what it will look like when completed.

 

[Grifflyer]

What would be a good propeller to put on this, i am using a 25a speed controller and this motor


https://www.amazon.com/dp/B07FMCHLFC/?tag=lstir-20

I am using this for a snow skimmer with a 850-3200 3s battery (depending on what balances the CG right.

A 6x4 prop should work fine for you.

 

[GMalatrasi]

Finally finished my Beechcraft Starship prototype!

Click Here for the full thread

 

[DamoRC]

Finally finished my Beechcraft Starship prototype!

View attachment 120787 View attachment 120788

Click Here for the full thread

Nice!

 

[SlingShot]

Flew these three guys today. Including the re-maiden of the Mini Cruiser. There's a review here.

Since Flite Fest Texas, I have already been through more batteries than the period between Flite Fest Florida and FF TX. Now, time to complete the B-25 and cut out the F-16 templates and get on with that

 

[jaredstrees]

I’m about to start cutting some f-16 plans out as well. Also going to tackle grifflyer’s new jet.

And Happy Holidays everyone!

 

[IcedStorm777]

Merry Christmas!