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Leaf Blower power?

Old 03-16-2010, 03:56 AM
  #1  
r4pt0r
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Default Leaf Blower power?

I am doing research to determine the plausibility of gutting a battery powered leaf blower, takeing its insides(battery included) and strapping it to a 4x8 sheet of 1 1/2 inch thich pink insulation, sanded and shaped using further 1/4in. Fan fold to build a 4 foot wingspan f-22 raptor. please comment. it should be 4 channel with the throtle servo moving a lever(if it is a variable speed blower) or just adding some kind of dimmer switch to the blowers circut, to be moved by the servo.
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Old 03-16-2010, 04:00 AM
  #2  
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My biggest concern would be weight to thrust ratio ....
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Old 03-16-2010, 04:02 AM
  #3  
kenchiroalpha
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Hi
Have you seen this yet?

Do enjoy
[media]http://www.youtube.com/watch?v=BylBraDRsJ4[/media]
Take care
Hank
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Old 03-16-2010, 04:33 AM
  #4  
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Originally Posted by r4pt0r View Post
I am doing research to determine the plausibility of gutting a battery powered leaf blower, takeing its insides(battery included) and strapping it to a 4x8 sheet of 1 1/2 inch thich pink insulation, sanded and shaped using further 1/4in. Fan fold to build a 4 foot wingspan f-22 raptor. please comment. it should be 4 channel with the throtle servo moving a lever(if it is a variable speed blower) or just adding some kind of dimmer switch to the blowers circut, to be moved by the servo.
Those leaf blowers would be using a brush type motor. It would require a brush type speed control or ESC. Nearly all electric models now being flown have gone to the brushless three phase motors, for less weight, and far better efficiency.

And, when you are working with a ducted fan or jet system, motor efficiency is even more important. You'd have a good chance of having a model that can not get off the ground.

I've got a gasoline powered leaf blower that I've measured the output air at about 160 MPH. But that blower only puts out something like 6 or 8 pounds thrust, and its running a 30 cc two stroke engine.
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Old 03-16-2010, 07:16 AM
  #5  
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I am also going to rain on your parade. I very much doubt you will get that setup to fly.

You will need to strip down the leaf blower to its absolute minimum weight.

Even then, your going to have a very heavy and very IN-efficient fan set up. Those blowers suck air in from the side and blow it out the end. The air has to change direction 90 degrees which make it waist a lot of energy. On top of that, that type of blower is much lower efficiency than a normal ducted fan. Then add on the weight.

If you had enough wing area to keep the wing loading very very low it might just be able to take off - maybe - but I seriously doubt it

That video is bogus by the way. You would get the same result twirling that leaf blower if it was turned off
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Old 03-16-2010, 07:36 AM
  #6  
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Originally Posted by Larry3215 View Post

That video is bogus by the way. You would get the same result twirling that leaf blower if it was turned off
Hi
It WAS posted as a joke and all in good fun
Heres some food for thought
[media]http://www.youtube.com/watch?v=l7DDLtotUvU&feature=player_embedded[/media]#
Take care
Hank
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Old 03-16-2010, 08:44 AM
  #7  
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First you need to estabish the weight and the thrust of the blower. Weight is easy and thrust can be measured quite simply by attaching the blower to some scales with the nozzle pointing up. Start the blower and see what weight increase the scales record.. this is the thrust.

Generally to be able to fly you will need thrust equal to at least 1/3rd of the total weight of the model, as an absolute minimum.. So if the model weighed 3lb you would need 1 lb thrust.. This ratio is a approximation, actual thrust depends on the efficiency and flying speed of the model. For a fast flying but inefficient design (like a scale F-22) that aim for something above a 1:2 thrust:weight ratio.. so the same 3lb model would need 1.5 lb thrust.

I'll wager that the blower alone has too low a thrust /weight ratio even before you go and build a plane around it.... Unless you do like the guy in the video and whirl it round your head on a string
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Old 03-16-2010, 03:08 PM
  #8  
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Well ive taken a look at the inside of a blower and it really is just a 5 in diameter EDF that is piped at a 90 deg. angle then spun 360 deg. then expelled. and as far as needing a esc, i plan on using the blowers built in battery, with one of my servos push/pulling on the on/off switch. not efficient, but this is just a proof of concept. i probably will change the design to an easier one, maybe even a profile flyer. i wont even paint it. here is a look at what my motor should look like: http://ecx.images-amazon.com/images/I/41AsrOmCTfL.jpg No 90 deg bend there.
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Old 03-16-2010, 04:27 PM
  #9  
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The fan you are talking about is fundamentally different to an EDF. An EDF is an axial fan, like a propeller.. The fan on your leaf blower is a centrifugal fan.

They work on very different principals. Generally the axial EDF type fan can move lots of air at high speed but low differential pressure. The centrifugal fan cant move as much air but is better at generating pressure.

Centrifugal fans are not usually very good for propulsion.

Have you measured the weight and thrust.. There is no point wasting time on the project if the basic thrust/weight figures donít add up.. and I donít think they will.

Steve
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Old 03-16-2010, 04:33 PM
  #10  
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Default Out Of The Box Solution

Its all about pitch on "axial" flow. As much as we all would like to say wow, a great idea...
I am afraid you are an echo to everyone reading this post. I observed that more and more
often these are serious posts not a joke. Many today do not remember or not old enough to
recall when we looked for magic bullets during the late 70's through the 80's.

Fans have gone from continually working on recip powered ducted fans to enjoy 1 flight a
day to today's solutions, right out of the box...

Well, even then it is occassionally entertaining if not alarming. Entertaining as this might
appear...you need to remember rotating masses can lead to funeral masses if you do not
read and heed the warnings and proper operating procedures. Like those on the side of a
leaf blower...


Last edited by Flite-Metal; 03-16-2010 at 04:59 PM.
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Old 03-16-2010, 04:48 PM
  #11  
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JetPlaneFlyer rocks;

No posting 'you can't do it', but posting 'this is what it would take to do it'.

nice!


So, take your leaf blower and test it like JetplaneFlyer says. I want to see the results. At the very least let us know what that leaf blower weighs with the batteries! Are they Nickle based? I would suspect so.....

FYI, ducted fans are fun to play with, consider this:
http://hobbycity.com/hobbyking/store...dProduct=11058

or to scratch up your own:
http://hobbycity.com/hobbyking/store...dProduct=11165
42oz of thrust, woot!
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Old 03-17-2010, 12:24 AM
  #12  
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The Black & Decker 18-Volt Cordless Broom weighs 4.8 lbs with un-modded(Long plastic tube, handle, all the unneccicary stuff) and has a 120 mph air speed at exaust. im going to get one and just take a look at it(perhaps tapeit to a skateboard and see its thrust.)
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Old 03-17-2010, 01:05 AM
  #13  
JetPlaneFlyer
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You cant tell the thrust just from the exhaust velocity.. you would also need to know the area of the outlet nozzle.

I've looked at photos on the net of that blower and the nozzle looks no larger than a slot 20mm deep and 50mm wide. Assuming they have the velocity right at 120mph and using my estimated nozzle area then thrust can quite easily be calculated using the thrust formula on this page: http://www.mh-aerotools.de/airfoils/propuls4.htm

Thrust works out at 180g, which is about the same as a 40mm GWS micro EDF unit with a brushless motor fitted. (For reference the GWS unit, battery, ESC and everything weighs about 70g)

The blower weighs 4.8lb.. lets assume you can ditch 1lb of platic junk.. that gives a total weight of 3.8lb (1.73Kg) plus the weight of the plane itself.. Lets say you buiilt the plane out of 'magic foam' that had zero weight, and your RC gear was also 'magic' and weighed nothing.

Thust to weight would be 180/1730 = approx 1:10 you would need a 300 - 500% increase in thrust to make it viable, even if your airframe was weightless, which obviously it really wont be

I think you should forget this now.. it's not going to work..far too little thrust and much MUCH too much weight. Just go buy yourself a proper EDF unit.

Steve
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Old 03-28-2010, 04:56 AM
  #14  
Bill G
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Originally Posted by kenchiroalpha View Post
Hi
Have you seen this yet?

Do enjoy
[media]http://www.youtube.com/watch?v=BylBraDRsJ4[/media]Take care
Hank
Worth the entertainment value Hank,
but I wouldn't exactly call it a "proof of concept" for anything other than maybe control line.

Originally Posted by kenchiroalpha View Post
Hi
It WAS posted as a joke and all in good fun
Heres some food for thought
[media]http://www.youtube.com/watch?v=l7DDLtotUvU&feature=player_embedded[/media]#
Take care
Hank
That guy actually had marginal success with a WWII German VTOL point interceptor.
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Old 04-30-2010, 05:57 PM
  #15  
crshbandit
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Default Moller Sky car

Hey guys, My Dad worked on the development of this prototype. He was a mechanical engineer specializing in Rotary engines. Do you think I could build an RC model of it? It would be cool to give it a shot. Thanks for any help you can give me.
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Old 04-30-2010, 11:58 PM
  #16  
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unless you got a degree in cybernetics, or electronics, i would not think too seriously about it.
that thing doesnt fly by itself, it needs 3 axis gyro stabilization.
and then its challenge of integrating that gyro into a well functioning fly by wire package.
for those who think gyro stabilization is simple, the next problem is to make the gyro work without fighting the pilots control input.
what cybernetic engineers would typically consider a good gyro, would be too stiff for a fly by wire application. it would feel like the plane was bolted to a set of rails, when flying it.
and if you can do all that. then, you can try shrinking it down to a package that realistically can fit into a model plane, both in shape, weight and size.
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Old 05-01-2010, 04:06 AM
  #17  
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While I dont think it will be nearly as difficult as Moxus thinks, its still going to be a serious challenge to build and especially fly a flying scale model of a Moller Skycar.

However, there are already a huge number of quad powered VTOL rc projects around so its far from impossible. Also, simple heading hold gyros as used in current rc helicopters will work fine for stabilization. As an alternate, the new generation of 3 axis gyros would also work as well and might be easier to integrate.

You wont have any problems with having to fight the gryos with either setup. They are designed to allow the pilot full control while augmenting stability in what ever axis you choose.

At a minimum you will need a very sophisticated tx with lots of programming options - not to mention a good bit of piloting skill

Have any of the full scale Moller Skycars actually flown? I havent heard any news about them in many years.


Below are some links to other quad powered vtol projects you may want to look into. Most all of them are simple rotors or ducted props as opposed to the ducted fans that Moller used.

The prop versions being far more efficient at generating thrust and so much lighter and less power hungry for any given setup. If you decide to go true scale and use ducted fans, you will have a much harder time getting enough lift for VTOL operation. Ducted fans are relatively in-efficient at converting power to thrust.

Do a search for "quadrotor" or "quadrotor helicopter" and you will get many hits.

The Moller is essentially the same thing using ducted fans instead of props and with the addition of tilting the fans for fast forward flight.

[media]http://www.youtube.com/watch?v=jt7qW2qNflI[/media]

http://www.rchelicopter.com/category...-rotor-design/

http://engineeringtv.com/video/Auton...tor-Helicopter

[media]http://www.youtube.com/watch?v=rJ9r2orcaYo[/media]

http://quadrotor.atspace.org/

http://robots.net/article/2992.html

[media]http://www.youtube.com/watch?v=n6uC6AasfJo[/media]

[media]http://www.youtube.com/watch?v=gd57F9pvTSw&feature=related[/media]

There are hundreds of similar projects if you search.

You might also do a search on RCGroups for similar projects. I know there have been at least a few with lots of build details. There may even have been a Skycar build. I havent been keeping up with that section of the hobby very well lately.
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Old 05-01-2010, 01:20 PM
  #18  
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Default skycar

While going thru alot of my dads stuff, I found loads of information on the skycar project. My dad did alot of testing on the engines for this vehicle. He never talked much about it , ( top secret??), so it just intrigued me as to the feasability of the project. I do remember him telling me once that the guy was a bit nutty and he was somewhat apprehensive about commiting 100 percent to the project as a consultant! I am going to study more of his work and if anyone would like to see what I find, let me know, and I will post it here. Thanks for all the good input, RC guys are still the smartest guys I know! Part of the reason I love this hobby!
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Old 05-01-2010, 02:03 PM
  #19  
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use heli headlocks, and the thing will fly like it was bolted to a set of invisible rails. as mentioned in my previous post aswell.
not what i call a good fly by wire system.
have you tried to fly a heli with a proper headlock, larry?
try using 3 axis of that. you can leave the aircraft hovering while you go for a lunch break.... thats not fun in my opinion.
thats stealing candy from a baby. and it has definetly nothing with flying to do, when the gyros do all the flying for you.
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Old 05-01-2010, 08:43 PM
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What in the world are you talking about moxus?

Every rc plane and heli ever built is fly by wire. I don't know of any rc planes where the pilot is directly connected to the controlls via cable or torque tubes - do you? Maybe you should look up the definition of fly by wire?

Also, I posted about a dozen examples above where this exact thing has already been done. Many with common rc gear and common gyros.

In fact they ALL use gyros. It cant be done any other way. How do you propose to control the throttle and pitch angle of 4 separate motor systems without some sort of built in stability control?

You are in fact contradicting yourself. The fly-by-wire and cybernetic controls you talk about in your first post are nothing more than remote controlled gyro stabilization systems. Something thats been around for ages.

As far as heli's and gyros, yes, Ive been flying helis for many years. Ive owned 6 different models from 250 size up to 60 size and all have heading hold gyros.

Thats they way ALL current CCPM heli's fly these days. Some of the toys still use rate gyros but even most of them have gone to heading hold. I dont see anyone complaining about lack of control or maneuverability.

Here is one fairly mild example for you. Doesnt look like he is being held back by the gryo does it?

[media]http://www.youtube.com/watch?v=AqZ-mCd0HhM&feature=related[/media]
You must not have ever seen any videos of 3D heli flying or done any heli flying at all for that matter.

Let me ask you - have you flow a heli without a heading hold gyro? If so I would love to see the video of that . If you have some examples of advanced heli flying - or any heli flying - without the use of gyros, please post them.

By the way, we used to do that - helis without gyros - way back in the ooooold days. Long before you were born would be my guess.

It didnt work out so well. So they started using mechanical gyros. That wasnt much better to tell the truth. Successful flights were the rare exception to the rule.

That was also waaaaaaay back before 2.4, expo, dual rates, computer radios, digital servos and many of the other good things that make flying heli's today possible for so many more people.

Back then model helis were about the rarest thing there was. Even when they came out with half decent electronic rate gyros, it was still a very elite section of the hobby. Heading hold gyros finally made it possible for the masses to get into heli flying. Even with heading hold gyros, heli's are still the most challenging aspect of the sport for most people.

As far as the 3 axis gryos, those are only being used on the newest heli innovations in flybarless flight.

In the ever increasing race for more radical maneuverability and more intense 3D action, the latest rage is to remove the flybar from the heli. This puts the pilot directly into fly-by-wire control of the blades pitch angle and removes the built in stability - and lag - that a bell hiller head with a flybar gives to a heli.

Without the flybar, most helis turn into psycotic beasts capable of truely extreme flying BUT having no built in stability. In many cases they are in fact grossly UN-stable making them virtually unflyable without the 3 axis gyro.

The 3 axis gyro makes them flyable WITHOUT removing any of the full range of maneuverability. Without the 3 axis gyro, 99% of them would be unflyable by 99% of the pilots out there.

There is no way anyone could fly a Moller car or any of those other quadrotor machines without gyros, so I dont see your point at all.

Last edited by Larry3215; 05-01-2010 at 10:19 PM.
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Old 05-01-2010, 08:45 PM
  #21  
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Originally Posted by crshbandit View Post
While going thru alot of my dads stuff, I found loads of information on the skycar project. My dad did alot of testing on the engines for this vehicle. He never talked much about it , ( top secret??), so it just intrigued me as to the feasability of the project. I do remember him telling me once that the guy was a bit nutty and he was somewhat apprehensive about commiting 100 percent to the project as a consultant! I am going to study more of his work and if anyone would like to see what I find, let me know, and I will post it here. Thanks for all the good input, RC guys are still the smartest guys I know! Part of the reason I love this hobby!
Id love to hear more about it. This probably isnt the best thread for that though as its way off topic from the first posters initial subject.

I would suggest you start a new topic on the Moller car. Id be willing to bet there are many here who would love to hear more about it and discuss ways to build a flying model.

Please post a link here when you do start the new topic!
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Old 05-02-2010, 03:37 AM
  #22  
Moxus
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larry, you (once again) read my posts like the devil reads the bible, just to find something to argue about.
and once again, i wont waste my energy on it.
and it seems to me you are again making statements way over your level of competence, and then blame it on me when you cant get the numbers you dont understand, to add up.
if you are interested in a constructive debate however, im in.
but i find that hard to believe from the way you express yourself.
the last time you were on a rant, i also clearly stated that as much as i wasnt wasting any energy on arguing with the devils advocate (being you), i also said that if you genuinely didnt see the issues with your black & white reasoning, i walk you through it.
i didnt hear any more from you, so i take it that you admitted for yourself you were just ranting.

i dont really understand what you want. in pms to me you call me a ignorant ass.
in the posts here in the forum, you are being the ass over and over again.
and i have repeatedly stated that im not interested in having any personal vendetta going on.
but it seems to me that you are VERY interested in just that.

unless i hear something constructive this time, i take it you are just being on a rant again?

Last edited by Moxus; 05-02-2010 at 04:02 AM.
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Old 05-02-2010, 04:18 AM
  #23  
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easy guys...
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Old 05-02-2010, 05:10 AM
  #24  
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Moxus, Larry, Be Nice to One Another, Love Betty

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Old 05-02-2010, 02:34 PM
  #25  
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<<<< counting to ten (and hiding from Chellie!) before I respond
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