Can you fly a good EDF design off a 3s 2200?

[The Fopster]

I'm planning my future building ideas. I'm finalising a mini golden age racer at the moment, but for my next couple of builds I'd like to try something new.

The first will therefore be my first twin - I'm going to build Jack Niezgoda's Mosquito (plans on 13thsquadron.com).

For the second I'd love to try building an EDF, but I'm trying to keep a lid on the costs so it needs to stick to the same 3s 2200 format battery that nearly all my planes use.

So - is there an EDF design that can still fly OK without going to higher cell count batteries? FT Viggen? Any others out there? If you've successfully built and flown an EDF off these standard batteries I'd love to know what airframe and what edf unit you used.

 

[whackflyer]

I think maybe @Captain Jay has experience with this type of deal. If you wanted to go for a manufactured plane, MotionRC has some 64mm ones that are only 100$ USD!

 

[Pieliker96]

The Viggen might work if you kept it light enough - taking the paper off inside surfaces, choosing a light EDF and ESC, no paint, minimal glue, adding lightening holes, etc. The main goal is keeping the thrust to weight ratio (TWR) high, which helps on launch and recovering from hairy situations. A TWR of around 1:1 is a good starting place for hand-launch EDFs.

You'll be fighting the fact that EDFs are necessarily high RPM devices. With a lower voltage, this necessitates higher kv which leads to higher amp draw. Since power loss is proportional to current squared (P = I^2 * R), you'll be a bit less efficient than a higher voltage, lower kv setup.

 

[leaded50]

at 3S most of the 50/55mm EDF have a thrust on 550g - 650g, 64- 70mm have approx 700g -1100g thrust.
As @Pieliker96 wrote, keep it 1:1.. in my opinion for easyer take-off/hand launching as minimum, the more "pluss" thrust, than weight of plane you have, the better.

 

[shadeyB]

FT Viggen
in the video she was flying 3s 2200mAh and flew pretty well even some high alpha a little
im sure it was 70mm at the time but cant remember the KV as it was some time ago.

most will fly from 50, 64 - 70mm om 3s set up but as mentioned above just keep your ration in line and all will be good for flying

 

[L Edge]

Once you get into EDF's, the first thing is you need to build super light as mention above. The more blades in the EDF, efficiency increases. When you add blades, the power need to be increased. So larger battery is needed in amperage and voltage. Not only that, you now have to add an additional cell(4s). The Viggen really performs when it has 4 to 6S.

If your goal is based on only using your 3S 2200 battery, it limits your pick of planes. 4S on 2200 would probably give you only 2 -3 min depending on throttle management. If you can find some 5 bladed 64 mm 3S motor using your 2200, the model will really have to be built SUPER LIGHT.

If 3S is your limit, look for some fighter planes that might be adopted to fit your situation.

 

[Pieliker96]

Once you get into EDF's, the first thing is you need to build super light as mention above. The more blades in the EDF, efficiency increases. When you add blades, the power need to be increased. So larger battery is needed in amperage and voltage. Not only that, you now have to add an additional cell(4s). The Viggen really performs when it has 4 to 6S.

If your goal is based on only using your 3S 2200 battery, it limits your pick of planes. 4S on 2200 would probably give you only 2 -3 min depending on throttle management. If you can find some 5 bladed 64 mm 3S motor using your 2200, the model will really have to be built SUPER LIGHT.

If 3S is your limit, look for some fighter planes that might be adopted to fit your situation.

I think you've got the relationship between blades and efficiency backwards - more blades means less efficiency due to the negative interactions of airflow between blades - the less blades there are and the farther apart they are, the better.

 

[Homey]

I think you've got the relationship between blades and efficiency backwards - more blades means less efficiency due to the negative interactions of airflow between blades - the less blades there are and the farther apart they are, the better.

Agreed, but 12 blade sounds awesome! Lol

Peter

 

[L Edge]

Don't forget that there is leakage of air going out the front when running. Compare the 5 blades area to the 12 bladed area means a higher internal pressure. There also is blade leakage forward between the tips and shell. It ends up quite a problem to solve. Plug one thing, changes the whole setup.

One trick I tried and worked is on a 5 bladed setup, there is a large gap between housing ands blades. I layed down 2 layers of Scotch magic tape to reduce the gap. Using the same battery full charged, first hovered the plane at 52 % throttle with just blades. Then with Scoth tape applied to the housing, plane hovered at 47%, proving(can't measure it accurately) the forward loss was reduced the blades and housing. Try it if you need more thrust from your setup.

 

[The Fopster]

As usual on this forum, lots of well informed and helpful input right off the bat. Thanks everyone - really useful input.

If I cut to the chase, though, the unanimous point of view seems to be it is possible to achieve my goal, but if I decide to stretch to better batteries I would do MUCH better on 4 cell or more. As I don't intend to start this build until the spring I've got time to look for some battery bargains in the sales...

Lots to think about! Thanks for all the advice so far.

 

[synjin]

Zepher1's F-86s are great, and I've flown my up sized version of his 50mm EDF F-86 on 3S (...My print settings were off and I was in a rush so didn't realize it was 126% until I had the wings cut out. They looked good, so I ordered a cheap 70mm EDF and kept going.). I think his 70mm EDF F-86 would fly fine on 3S. Build light and mind your CG.
https://forum.flitetest.com/index.php?threads/f-86-sabre-70mm-edf.58198/

 

[cosmocop]

I've built quite a few EDF's from scratch. I'd say a 3s 2200mah battery is going to limit your options.

I'd also have to disagree with earlier thrust figures. I would say (for 3s setups that aren't high amp draw) you're looking at 350-450g (50mm) and 450-600g (64mm). I haven't seen many 70mm 3s setups.

As for T/W, 1:1 is preferred but I've been successful with 0.8/1. Success for hand launch can be dependent on many factors (wind, running start, launch angle, static thrust, throwing form, etc.)

In general I'd recommend going 4S. If you have to go 3S, I'll echo what others have said and recommend that you build light. If I were to try this, Viggen would be my first choice, but getting a good underhand launch on 3s might be tough.

 

[leaded50]

I think you've got the relationship between blades and efficiency backwards - more blades means less efficiency due to the negative interactions of airflow between blades - the less blades there are and the farther apart they are, the better.

well..... 64mm ducted fan QF2822 4300KV,5 blade, thrust 3s: 1100g, 466W.
a 64mm ducted fan QF2822-3500KV 12 blade, thrust 3s:1230g, 850W .
. The more blades, the more powerful/efficient at take off/acceleration, the lower blades, more speed, but suffer acceleration.

 

[The Hangar]

Buy a fan specified for 3s use, and you should be good. Others have mentioned the viggen - it’s a great platform that can be built fairly light. The new Habu from eflite runs off of 3s and 4s.

 

[cosmocop]

I know they are advertising those thrust numbers but I personally don't believe them.

Your average 30A 3S 6 x 4 prop setup will produce 750g. Hard to believe a 4300KV 3s 64mm EDF setup puts out 350g more (even at 42 amps).

In my opinion, the 3500KV numbers don't sound right either (at least for 3s). I would think you'd run a 3500KV at 4s and expect a 12 blade to put out something like 1000g (not installed in airframe).

Generally, more blades will sound better and have better midrange performance, at the expense of efficiency (flight time) and top speed.

Just my $0.02.

 

[Pieliker96]

well..... 64mm ducted fan QF2822 4300KV,5 blade, thrust 3s: 1100g, 466W.
a 64mm ducted fan QF2822-3500KV 12 blade, thrust 3s:1230g, 850W .
. The more blades, the more powerful/efficient at take off/acceleration, the lower blades, more speed, but suffer acceleration.

1100g / 466W = 2.36 g/W for the 5-blade.
1230g / 850W = 1.45 g/W for the 12-blade.
The twelve blade produces less thrust per unit of power and is therefore less efficient.

 

[Daniel Liutan]

well..... 64mm ducted fan QF2822 4300KV,5 blade, thrust 3s: 1100g, 466W.
a 64mm ducted fan QF2822-3500KV 12 blade, thrust 3s:1230g, 850W .
. The more blades, the more powerful/efficient at take off/acceleration, the lower blades, more speed, but suffer acceleration.

Some data from EDF producer:

Top two images are 5 blades EDF, bottom one is 12 blades, different moto (that's why different thrust) ,but similar KV for the bottom two.

Less blades, more efficiency, smaller Amps, give more thrust at same Amps compare to 4S, shrill sound;
More blades, less efficiency, larger Amps, whoosh sound like real turbine jet;

More cells, less efficiency.

For 5 blades EDF, with 40A ESC can give you 800g thrust at 3S, 1200g at 4S;
For 12 blades, need 60A ESC.

So if you want use 3S lipo with EDF, the AUW should be less than 600g for a discent performance.

Also, the discarge rate of the battery is quite important, 40C least recommanded.

 

[jfaleo1]

I'm planning my future building ideas. I'm finalising a mini golden age racer at the moment, but for my next couple of builds I'd like to try something new.

The first will therefore be my first twin - I'm going to build Jack Niezgoda's Mosquito (plans on 13thsquadron.com).

For the second I'd love to try building an EDF, but I'm trying to keep a lid on the costs so it needs to stick to the same 3s 2200 format battery that nearly all my planes use.

So - is there an EDF design that can still fly OK without going to higher cell count batteries? FT Viggen? Any others out there? If you've successfully built and flown an EDF off these standard batteries I'd love to know what airframe and what edf unit you used.

I am still flying a White Diamond with a 50mm Hobby King Alloy EDF (3s version) and it flies very well. Look up @JGplanes White Diamond thread and think it over as a test aircraft. But you are correct that a 4s setup is generally better and easier to set up a good plane on. @Grifflyer has a great L-39 (v2) or @Zephyr1 has an F-86 either of these are great 50mm 4s aircraft.

 

[leaded50]

everybody who has flew with different EDF´s knows push on a 12 blade in take off, is better than by a 5 blade. Yes more wattage, eg.

 

[L Edge]

As usual on this forum, lots of well informed and helpful input right off the bat. Thanks everyone - really useful input.

If I cut to the chase, though, the unanimous point of view seems to be it is possible to achieve my goal, but if I decide to stretch to better batteries I would do MUCH better on 4 cell or more. As I don't intend to start this build until the spring I've got time to look for some battery bargains in the sales...

Lots to think about! Thanks for all the advice so far.

Did you see the video above MAIDEN VIGGEN FT using a 64 4s with 2200? Again, pick a 70 4S and you will have more choices of planes to build. Pilot is yves.morele.