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Old Nov 13, 2012, 04:59 PM
Capt. Z
falcon5's Avatar
Tonopah, Nevada
Joined Dec 2004
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For planning and to get an idea of large EDF possabilities here is a twin Stumax 100mm EDF powered 12 foot long T-38 that flew decent on 6000 watts per fan for about 28 pounds of thrust. The plane weighed 44 pounds AUW and with onboard GPS reported 135 mph on a flat pass, calm wind.

T 38 3rd flight1 (1 min 34 sec)
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Old Nov 14, 2012, 12:47 AM
310mph Kolibri T25 Swist
henke's Avatar
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Originally Posted by Double E View Post
My understanding is that the efflux speed from the turbine is much higher than the EDF and that is why a 5 lbs thrust turbine would outperform a 5lbs thrust EDF.
That is very true! I found from my experiences that you need twice the thrust from an EDF to equal a turbine. Only when starting from grass is the more powerful EDF is superior to get it rolling. When flying the turbine uses it's efflux speed to keep the thrust at any speed we fly at.

Even for a vertical manover where you think thrust is the winner the turbine with half the static thrust equals the more powerful EDF as the EDF apparantly only has half the trust avalable at cuising speed.

The L39's linked are however floaters, they fly very very slow for the size. All pilots I've spoken with agree it's ridiculous slow and not scale like at all. This is ofcause good for the EDF setup. whe you could probably aim for the lower turbine recomendations (16kg), which useing my rule of thrumb would equal a 32kg(70lb) thrust EDF setup.



As mentioned before, this is one way of doing it :-)



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Old Nov 14, 2012, 12:52 AM
310mph Kolibri T25 Swist
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Originally Posted by Double E View Post
Okay Terry, I think I found the single fan solution.

http://www.schuebeler-jets.com/en/ne...er-2012en.html.

This new giant Schuebeler fan is suppose to produce close to 54lbs of thrust.
That would in my mind be equal to a 12-13kg thrust turbine
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Old Nov 14, 2012, 04:40 AM
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Originally Posted by henke View Post
That would in my mind be equal to a 12-13kg thrust turbine
I haven't seen anything to prove that EDF as a whole doesn't put out the CFM of a gas turbine...
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Old Nov 14, 2012, 05:05 AM
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Molde, Norway
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Originally Posted by henke View Post
That is very true! I found from my experiences that you need twice the thrust from an EDF to equal a turbine. Only when starting from grass is the more powerful EDF is superior to get it rolling. When flying the turbine uses it's efflux speed to keep the thrust at any speed we fly at.

Even for a vertical manover where you think thrust is the winner the turbine with half the static thrust equals the more powerful EDF as the EDF apparantly only has half the trust avalable at cuising speed.

The L39's linked are however floaters, they fly very very slow for the size. All pilots I've spoken with agree it's ridiculous slow and not scale like at all. This is ofcause good for the EDF setup. whe you could probably aim for the lower turbine recomendations (16kg), which useing my rule of thrumb would equal a 32kg(70lb) thrust EDF setup.



As mentioned before, this is one way of doing it :-)
Henke, I don't really agree with you on this, if you where right on this then lots of planes flying very well on EDF power should not be doing so. However, when we are talking about extreme speed, like 200mph+ then yes turbines have a very definite edge over EDF. Simple reason of course that even the more extreme EDF setups do not have efflux speeds beyond 300mph so they have very little thrust left when the plane is going very fast. But, most jet flying is done at lower speeds, like 100-200mph and that's a different story.

I have a CARF MiG-15, and it flies on 90N installed thrust, if you did not know if was flying on EDF power it could just as well have a turbine installed, by your reckoning I would have to have 160N of EDF thrust to equal a 80N turbine and that is just plain wrong in that kind of plane. Same goes for a Eflite F-4, I think my SM80 fan unit that's in there puts out 5.5lbs or so of thrust, about the same as a P20. Now, I'm pretty sure the plane may be faster with a P20 but it's still no underpowered pig with my EDF setup, speed and vertical performance is still very good considering this is a 7.5lbs plane.
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Old Nov 14, 2012, 06:27 AM
KingtechUSA
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Tampa FL
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Well this last weekend I was flying at a scale event and got to see a towmahawk BAE hawk. Was very impressed by how light it is. The construction was great.

Only thing is I think some things where built a little to light. Like the gear cyclinders for the retracts and the brakes. Both had leaks and had to be taken apart and cleaned and lubed to work at the feild and it was crazy how thin the metal was. But it is very light and very well made. The brake cyclinder had a slight warp to it and you could bend it very easy and cause the O-ring to leak.

He had a P200 for power and it was perfect! Nice knife edge passes a few feet from the ground and long flights. Pablo even said he has seen some people put 5 pounds of weight on the CG just to make it fly a little more scale like because they are so light the wind throws them around. This hawk had 3 gyros on it and was rock solid but did seem a little to light.

The L39 is a little bigger then the hawk. I have no doubt it will fly EDF. But at the end of the day you will have a plane that flies like a big kite for 3 mins and will be pushing the power system to its limits. It does not sound very enjoyable.
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Old Nov 14, 2012, 07:29 AM
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Quote:
Originally Posted by falcon5 View Post
For planning and to get an idea of large EDF possabilities here is a twin Stumax 100mm EDF powered 12 foot long T-38 that flew decent on 6000 watts per fan for about 28 pounds of thrust. The plane weighed 44 pounds AUW and with onboard GPS reported 135 mph on a flat pass, calm wind.
Very nice Falcon. Sounds great!!

Terry
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Old Nov 14, 2012, 07:57 AM
310mph Kolibri T25 Swist
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Originally Posted by erh7771 View Post
I haven't seen anything to prove that EDF as a whole doesn't put out the CFM of a gas turbine...
CFM it might but efflux not. As you accelerate the static thrust of the turbine remains while the EDF suffers.

In the 90mm range of EDF there are alot of real world compartions to prove my theory. Habu32, GBR jets stinger, various JTM planes and so on.

These two guys pushes the same static thrust through two very diffrent outlet areas

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Old Nov 14, 2012, 08:14 AM
310mph Kolibri T25 Swist
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Originally Posted by Arngeir Blakseth View Post
I have a CARF MiG-15, and it flies on 90N installed thrust, if you did not know if was flying on EDF power it could just as well have a turbine installed
Then I bet it would fly very well on a P60 turbine which installed would put out mabye 50N.

Here is a futura with a P80Se turbine. The turbine is rated at 22lb and we all can agree it problably won't put out more installed. Probably around 17lb or so as it looks to be a sunny day.

Tomahawk Futura 1.9m First Flights (5 min 57 sec)



Here is the same plane useing an EDF setup said to push 20lb of thrust by the owner (who is also on this forum)
BURNING ESC ON EDF TOMAHAWK eFUTURA - HOPFARM SOUTHERN RC MODEL AIRSHOW - 2011 (4 min 27 sec)
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Old Nov 14, 2012, 08:25 AM
310mph Kolibri T25 Swist
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Originally Posted by Arngeir Blakseth View Post
Same goes for a Eflite F-4, I think my SM80 fan unit that's in there puts out 5.5lbs or so of thrust, about the same as a P20.
If you have seen one fly (even faster then your EDF setup) you must be convenced I'm right. As a P20 isntalled with a bifurcated thrust tube in the Eflite F4 would put out a maximum of half the rated thrust. Tam dind't even dare to tell how much thrust was left efter fitting it with his $400.

I'm not holding the main topic back, I just don't want anyone to run away and buy a very costly Schubeler fan which might not be up to the job in a satisfying way. I'm sure it would fly the big L39, but not in a fun way.
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Old Nov 14, 2012, 09:06 AM
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Originally Posted by gunradd View Post
... This hawk had 3 gyros on it and was rock solid but did seem a little to light...
Was this a 3 axis stabalizer or 3 different gyros?

Quote:
...The L39 is a little bigger then the hawk. I have no doubt it will fly EDF. But at the end of the day you will have a plane that flies like a big kite for 3 mins and will be pushing the power system to its limits. It does not sound very enjoyable.
There are sweet spots for EDFs, it's been proven on smaller fans using two EDFs is way more efficient than using one fan and shoving a ton of watts through it
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Old Nov 14, 2012, 09:19 AM
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Originally Posted by henke View Post
..I'm not holding the main topic back, I just don't want anyone to run away and buy a very costly Schubeler fan which might not be up to the job in a satisfying way. I'm sure it would fly the big L39, but not in a fun way.
I've seen shuebs push fairly large jets around fairly fast for a decent amount of time...

Two shube 128s would be 40 - 44 lbs of static thrust at 12s 5000 watts each....

What's that?

around 6 - 8 lbs of battery depending on the packs?

You'd get pretty decent flight time with that...

The fan ran at even lower power will still push the the bird in question around if I get the need thrust correct
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Old Nov 14, 2012, 10:24 AM
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henke, this project must be edf. While I would like to build it with a P200, that is just not an option.

My initial blush on this power plant is 2 120-127mm fans running 14S 8000 batteries each. While I like open inlet systems, the idea of a fan as large as 195mm running open quite honestly scares.

Some quick and dirty calculations I did puts the P200 powerplant complete with fuel at about 18-19 lbs and from the literature I read capable of 52 lbs of thrust.

A single DS-215-HST with 14S 16000 mA batteries comes in about 20 lbs not counting the huge wire requirements and a stated 50 lbs thrust.

Various 120-127mm dual fan systems with 14S 8000 per side are about 22 lbs with 44-48 lbs thrust.

By biggest question right now has to do with the thrust tube and any losses that may be associated with it as well as the best way to optimize.

Terry
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Old Nov 14, 2012, 11:06 AM
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Molde, Norway
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Quote:
Originally Posted by henke View Post
If you have seen one fly (even faster then your EDF setup) you must be convenced I'm right. As a P20 isntalled with a bifurcated thrust tube in the Eflite F4 would put out a maximum of half the rated thrust. Tam dind't even dare to tell how much thrust was left efter fitting it with his $400.

I'm not holding the main topic back, I just don't want anyone to run away and buy a very costly Schubeler fan which might not be up to the job in a satisfying way. I'm sure it would fly the big L39, but not in a fun way.
How you figure out that a large Schubeler fan producing 54lbs of thrust will not be up to the job is beyond me, my personal experience says it will work fine. We are talking about a plane that will be weighing maybe 60 lbs, so it will have a thrust to weigth of close to 1:1. If a 30lb MiG-15 flies fine on 19lbs of EDF thrust then why would this plane do any worse with a better thrust to weight ratio?

The DS-215 makes the same amount of power as a P200, and installed weight ready to fly is about the same, and total cost is also on par with the turbine.

Expect to pay maybe 2000-2500 Euro for the fan, another 500Euro for a 400A MGM Compro esc and then batteries depends on make and size. A P200 costs what, around 4000Euro? That's 1000-1500 Euro to pay for batteries to equal the cost of the turbine. And it costs a lot to pay for the fuel to run that thirsty turbine as well so that has to be figured into the budget also.

As for the F-4, I have not seen one fly on a turbine, what I said was simply that I would expect one with a P20 to be a bit faster than mine given that the P20 and my fan makes the same amount of static thrust, but I doubt it would be that much fun to fly if the install robs it of half the thrust as you say. Have you tested this btw, or is it just an assumption on your behalf? Now, I'm sure I don't have 5.5lbs installed either but the losses due to the bifurcated thrust tube is not that big.

But I guess you have made up your mind about turbines being superior in any way to EDF so there's really no point in continuing to argue about it. To each his own.
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Old Nov 14, 2012, 11:19 AM
310mph Kolibri T25 Swist
henke's Avatar
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Originally Posted by Arngeir Blakseth View Post
But I guess you have made up your mind about turbines being superior in any way to EDF so there's really no point in continuing to argue about it. To each his own.
That's a strange assumption which is not true. You just cant say 50lb EDF thrust will fly a plane in the same way as a 50lb turbine powerd one. I'm speaking of what I have seen and tested my self. If I were to buy any setup rideing a €15000 airplane I would defenently do my homework and not just listen to the fanboys who shout the loudest either it's turbine or EDF.

I'm not arguing about cost, running costs, weight, ease of use, tendency to catch fire, ability to pull chicks or even performance. Only that you can not compare lb and lb of thrust here.

If setup to 45lb of thrust expecting it to go like the P200 powerd ones you will be disapointed. It's that easy (personally I think it's under powerd with the P200 too)
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Last edited by henke; Nov 14, 2012 at 11:31 AM.
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