ElectroSport Stunt: A matter of time?

LAST EDITED ON Nov-29-03 AT 04:45 PM (CST)
 
So how long is it before someone combines the ARF Flight Streak with an electric power package to give us a silent stunt ship with credible performance?

Inquiring minds want to stimulate the engineering debate...

Cy.

P.S. The reason I ask is that a fellow I know is building a radio control Eureka B-36 with 6 electric engines that work out to be roughly the power of a .25 and he expects to get 15 minute flights on a charge.

The electric R/C guys have a thing called "E3-D" which is their term for full tilt boogie aerobatic capable electric powered airplanes.

These things are capable of driving a 13x6.3 prop hard enough that they can stand the airplane on the propshaft and hover. Which implies they can open it up a bit and climb. They have flights as long as 25 minutes.

http://www.rcgroups.com/forums/showthread.php?s=0102d883b44eb113c05229a9708e9fe1&threadid=162689

That and other things tell me that the electric powertrain is developing rapidly.

The E-3D models look a lot like our stunt ships though, with thick symmetrical airfoils.

I get the feeling that something is going on that we are missing in our "knowledge" that stunt ships are powered by 2 or 4 cycle gas engines.

A relatively cheap stunt trainer that was silent could go a long way to reclaim a bunch of lost flying sites, which in turn would attract new members to the sport/hobby. It might be in all our best interest to explore this.

Just a thought.

Three years, eight months, 14 day's, two hours, and 44 seconds.

scott(I'm in the pool)Riese:+

Although I was wrong about whether or not we would ever see ARF CL models, my view is that true electric-powered CL Stunt models, pieces which would give satisfactory performance without a lot of hassle, are a good ways down the road. As in years, not months.

The 3D models you cite are indeed pretty cool. But they are built very lightly, have as a primary benefit the recent development of incredibly light RC systems, feature high-cost power trains, most notably the battery packs.

And they do not have to drag around a set of lines.

Part of the problem here is that "our" market consists primarily of contest-capable equipment. And it is very small.

None of, for example, the folks at the Team Trials wants to fiddle with electrics, as there simply is no performance advantage.

(Yes, I am aware of Shulman's electric-powered FAI-specific RC Pattern model. Some of that technology does appear to be transferrable to, say, an Impact, although it doesn't look as if 40VF- or Saito 56-like performance could possibly be the result. When factoring in the Saito 72 and its output, there is no hope.)

In RC, however, the market is much larger, the sport flier is all that counts. So the manufacturers, who can so much more easily afford to develop the technology, indeed have a profit motive to do so, have come up with all kinds of pretty cool stuff.

Will they do so for us CL folk? I think not, although it would be nice to be wrong about this.

In an earlier thread, Larry Cunningham had a charting of the energy density of several options we have available. A look at this has to be very depressing to anyone contemplating an electric-power CL model, whether a full-boogie piece or even just a small trainer of some sort.

I think I misstated my idea, probably by putting the Nobler where the Flight Streak should have been. Or better yet, an E3-D ship with a bellcrank.

>Part of the problem here is that "our" market consists
>primarily of contest-capable equipment. And it is very
>small.
>

Well, I dunno about your market, but I'm thinking of control line in general in this context.

The market for contest capable equipment (Hmmm. A R)-Jett Bar Stock Engine with tuned carbon fiber pipe and...you know the rest better than I) is going to be increasingly restricted to the top competitors the more refined the product is.

But that's against the grain of my query.

If a viable ARF electro sport stunt ship could be sold at Tower for, say $30 more than an ARF no motor ship, then we might attract a whole new batch of fliers to the visceral thrill of actually feeling the airplane fly.

No, these ships are not going to win at the Nats, but then that's not the intention.

>None of, for example, the folks at the Team Trials wants to
>fiddle with electrics, as there simply is no performance
>advantage.

Those guys are already in the sport.

Where are all the kids going to go who walk into a hobby shop now and walk out with a flying wing or stunt truck R/C?

Not into control line, unless we offer them a route.

>In RC, however, the market is much larger, the sport flier
>is all that counts. So the manufacturers, who can so much
>more easily afford to develop the technology, indeed have a
>profit motive to do so, have come up with all kinds of
>pretty cool stuff.

And they won't bother to do much for us until we nurture a market.

And thus the idea of taking an off the shelf Electro 3-D ship or ARFlight Streak and adding the bellcrank or powertrain and defining a new genre of C/L that might attract kids.

Actually, Electro Sport Combat might be a real hook for the Generation Z'ers or wherever we are in the alphabet these days. And silent flight will open up a bunch of new (old) venues.

>In an earlier thread, Larry Cunningham had a charting of the
>energy density of several options we have available.

From what I am seeing, the options are changing daily. It's already at the point where you have to use a piece of software to match your engine, prop and batteries to the airframe.

> A look
>at this has to be very depressing to anyone contemplating an
>electric-power CL model, whether a full-boogie piece or even
>just a small trainer of some sort.

When I say full boogie, I'm talking about a ship a kid can buy in a hobby shop, charge up, hook up and go flail to his ability to avoid the ground for 10- 12 minutes and get into the experience. Not a machine that will just barely fly for lack of power, but at the same time certainly not anything competitive at the team trials. Anyone going there is target fixated on gas engines in any event..

If the right craft emerges, how hard would it be to take all the overheads out of the stunt pattern and come up with an Electro Stunt category with a known sequence commensurate with the abilities of the airplane.

I'm trying to bend the sport to match the opportunities of the times not the opposite.

Cy.

>>>They have flights as long as 25 minutes<<<

Those 25 minutes is exactly the problem. If you mean serious power train we need relatively large amount of power, and you must to store it somewhere. Actual NiCd and NiMh batteries are out of sense as such 12V 2500mAh batteries for 200-300W is ~600g heavy and it is like piped 10ccm power train. So the only way is LiPoly or LiIon cell and actual cells are not capable to deliver such current and that is the reason why they fly 25 minutes. We fly 6min so it needs cells giving 10C current. Actual large capacity cells give maximally 6C – 7C CONTINUOSE drain – means you must carry unusable capacity and it is dead weight also.

But there are already new small Kokam cells giving >6A from 10g weight (actually 20C), but they are small, only 350mAh.

So I would say – give it another year or two … I am already working on regulator for brushless engines properly feeding whole flight, may be I will finish it till that time

But do not think it is silent, the prop at 10 000 makes lot of noise also without exhaust

As all participants in this forum already know, an electric powered Twister has flown a 497 point pattern. This is old technology! My guess is that we will see a pattern-capable sport/stunt electric ARF on the market within the next couple of years. I suspect there will be a large enough market for it that some good money will be made. It will be interesting to see which company comes out with it.

LAST EDITED ON Dec-13-03 AT 04:28 AM (CST)
 
Here some pictures of an electric stunter of Jan Odeyn, Belgium.
It is capable of al the manoeuvers of the book, in reversed order and with only 1 lap in between.

I knew it!

Specs, plans, details?

One thing I notice about electric is the complexity of selecting all the components in the power train has resulted in software to assist the designer in sorting out the prop, engine, gearing, batteries, etc.

What are the details of this aircraft and power train. if the designer is willing to share?

Exciting stuff!!

Cy.

The model is a 120% version of the one published in aeromodeller of august (?) 1998 with enlarged tailmomentarm.

Wingspan = 120 cm, chord = constant 22 cm, full span flaps have 6 cm chord
Elevator throw = 40 degrees each way, flap throw = 25 degrees each way.

Very important is the wingprofile: A very thick wing with a round leadingedge and very forward point of maximum thickness.

Engine is a Graupner speed 600, 7 Sanyo cells of 1700 mAh
Belt reduction gear 1/2,5
Prop is 11x8 Graupner Cam prop.

Modelweight all in is 1200 grams

The flightduration is 4 minutes +.

Last info: No special order of meanoeuvers Only 1 lap between maneuvers.

The model rises from concrete. Handlaunch is recommended above grass.

Regards,
Paul

Thanks, Cy,Steve,Paul and Jim T. All of you really contributed to this discussion. Now, for fear that I will be told that "STunt rules" don"t allow throttle control--Why can't we do that?
Fred Cronenwett has developed a very good system of sending a "signal" down the lines to control throttle. This is done with ONE line insulated. We do it all the time in carrier, scale--why not in stunt? Am I wrong in thinking that you can reduce power (to save your battery) on level flight and down hill. When the pattern is over with, just land!!! Granted, you won't fly with the engines--make another class of stunt for electric's!!! Steve, you seem to have a grasp on the "electronics of this" Thanks again Cy for a good topic.
The recv. we have are the size of a postage stamp--servo's are in grams and you use the main battery to power the Recv-servo set up.Why, can't we???

LAST EDITED ON Dec-13-03 AT 03:49 PM (CST)
 
If anyone is interested in throttle control or switching down the lines (not power) here's a page I put up ages ago with a few simple circuits to experiment with. They work for me though I haven't tried anything bigger than a Speed 400 with those circuits http://www.slewin.clara.net/elec/ecl.htm As Dave says one insulated line is all you need.

Sorry I haven't updated it for a while. I'll include the infra red circuits I've now moved onto as soon as I get time to do some proper testing and then write them up. It might help if I could fly better then I'd perhaps do less model repairing .

Bear in mind that all this stuff is experimental. I enjoy messing with electronics and I'm happy to share anything I'm playing with but I'm not a professional electronics designer so it's all a bit crude and simple-minded. E.g. I build most circuits on stripboard so they're big and bulky compared with modern electronics.

LAST EDITED ON Nov-29-03 AT 08:53 PM (CST)
 
Having done a little RC electric, I have a few comments.
1) The vibration due to electric motors is really insignificant, so airframes can be made really light. They need to be to carry the extra weight of the motor and batteries. So even the Arf Nobler needs to be lightened up
2) There is a lot of hype, but things have really improved a lot since I dipped my toes into the electric "field". Among these are that batteries have really improved, as well as the new brushless (and expensive) motors.
3) Electric certainly isn't cheaper than nitro-methanol-oil fuels.
4) One trick will be adjusting the motor run to deal with the last part of the pattern--which I think is more stressful than the early part. I am not sure whether this requires some type of motor control.
5) Electric stunt is probably coming (or is already here and we don't recognize it), but probably will take an expert "true believer" to convince the upper level PA experts that it is viable (sort of like the Netzband Paradox--you can build it but they won't come!).

LAST EDITED ON Dec-01-03 AT 04:49 AM (CST)
 
There's this RC 3D model I've seen that's made out of bare foam, with a 3/4" thick foam profile fuse and some carbon rods used as stiffeners. It flies astoundingly well. I'm going to copy it and put a bellcrank in it, and use a direct drive instead of the geared motor (not too interested in hanging by the prop). It'll probably fly great indoors on 35 foot Spectra lines.

Some of these electric motor/gearbox/propeller combos are really, really cheap (have a look at Tower Hobbies - some are under $20).

>5) Electric stunt is probably coming (or is already here and
>we don't recognize it), but probably will take an expert
>"true believer" to convince the upper level PA experts that
>it is viable

Good points, Alan, but it may not be necessary to convince upper level PA pilots. Experts haven't formally blessed the Top Flite arfs, but that hasn't stopped people from buying them. I have two. Cy makes an excellent suggestion. His idea is for a viable electric sport-stunt CL airplane, not a top level competition PA ship. I think any new idea for expanding CL participation might be valid. And I'd love to see an electric cl arf appear. Let's let the market decide.

I guess one point I was trying to make and didn't make particularly clear was that I think that it is probably necessary to build the electric stunter first. I am not sure if the Nobler or Streak Arfs are light enough as is. They are pretty light--I have both and am pretty happy with their flying capabilities--with lightweight engines. However I am certainly curious to see someone convert them to electric.

what about powering the electric motors with the battery pack at the handle end and running the current up the wires. Is there sufficient current and power to drive the motor through that long a wire transmission? This would significantly reduce the weight of the bird.

Bob Smiley
A Lancair 360 builder/flyer trying to be a modeler.

Not really. You're talking several amps, maybe tens of amps.

You can go to higher voltage, so you will need less amperes and you will save lot of power (P= U * I ^2), but in that case it is question of insulation … but what about induction or laser ? ... no forget it ... solar pannels on wing

Induction would be a real trip... All the credit cards for half a mile around would go bad..

What I believe to be the world's first ever electric C/L sanctioned events will be held on March 6-7, 2004 at in Cedar Falls, Iowa! It's the annual UNI DOME INDOOR FLY-IN, and this year 3 control line events are on the schedule.

Check it out:
http://showcase.netins.net/web/sig/unidome2004.html

This is the 4th year for the UNI Dome Fly-In. A couple of us have flown electric control-line models at the UNI DOME in previous years, but this is the first year that we will actually hold events. The events are: Fun Scale, Stunt, Balloon Bust.

Fun Scale and Balloon Bust would be the easiest to get in to. Simply take any current R/C "park flyer" and put in a bellcrank.

The stunt event will, of course, be a bit more challenging. Mike Pratt and myself are still formulating the rules for this year's UNI Dome stunt event, which we will be running (and flying). For the innaugural event, we will undoubtably keep the maneuver list short, to encourage as much participation as possible. NOTE:: At past UNI DOME fly-ins, we've seen scratch-built Speed 400 powered electric control line models do inside and outside loops and fly inverted. Not that much more isn't possible with today's technology, but for starters we don't want to discourage anyone from giving it a try. We hope that this year's events will be fun and get people thinking about experimenting with the readily available electric gear that's out there now.

OUTLOOK: There will be "full house" electric C/L in the future. There can't be much doubt about that. As I've said before on this forum, the technology and products are out there right now to make a very viable C/L precision aerobatics model, but that level of high performance product is still quite expensive (Hacker brushless motors at $300 each), and I don't know of too many guys willing to spend that kind of money on experiments. But, as always happens, the high prices will come down for these products, as even better products are developed. For instance, a new line of high performance brushless motors - MAXX Products (sorry for the commercial plug, but it's the truth)- that are made in China and cost much less than the European brushless motors is hitting the market right now. One thing about it, electric flight is the most dynamic (meaning fastest growing and constantly changing) area in modeling at the moment.

And did you know that the CEO of GWS (the biggest name in electric park flyers in the world) is a lifelong C/L fan and intends to bring out product for C/L? It's starting to get pretty exciting!

Mike Gretz

But what is the impact on the sport flyer, or the person with minimal involvement in CL, buying an ARF for the first time?

Many RCers are getting their start this way.

My opinion: If it comes to pass, it has to be a boost for the hobby. I'm not saying it is analogous to the late '40s boost that glow gave our hobby, but...still a boost.

Especially if marketed properly.

LAST EDITED ON Dec-02-03 AT 10:54 AM (CST)
 
>But what is the impact on the sport flyer, or the person
>with minimal involvement in CL, buying an ARF for the first
>time?
>
>Many RCers are getting their start this way.
>
>My opinion: If it comes to pass, it has to be a boost for
>the hobby. I'm not saying it is analogous to the late '40s
>boost that glow gave our hobby, but...still a boost.
>
>Especially if marketed properly.
>
>Currell

How many remember how we got started in modeling? I bet it was with one of the Scientific/Musciano "hollow logs", or something equally as inexpensive, attached to a barely adequate $4.95 +- 1/2A engine. Anemic? yes, but it FLEW, and was the intro to modeling for just about everyone whose pappy was not rich. Tens of thousands of us? Probably more. I think that well-performing, relatively inexpensive and reliable electric models are just the kick needed for all levels of the hobby, not just c/l; something to provide a minimum level of frustration for lots of fun! Those who wish to progress will, and THAT's how modeling of all flavors will survive into the foreseeable future.

>.
>
>The stunt event will, of course, be a bit more challenging.
>Mike Pratt and myself are still formulating the rules for
>this year's UNI Dome stunt event, which we will be running
>(and flying).

Mike and Mikey,

If Palko were to show up with his electric neither of you would have a snowballs chance. His is capable of the entire AMA pattern with some decent shapes, although the squares are still a little soft I have been told. 497 points on a flight somewhere too! I believe that in about three to four years the electric technology will have advanced enough for a viable stunt pattern, although not in seriously windy conditions.

I can just see it, inverted flight, no solar panels on the bottom of the wing, and I crash when the motor stops. Arrgh. So solar panels on the underside too.

One thing that will help in keeping down the weight is the total lack or need for dope. Just cover it. No fuel residue, no nitro, no need for dope. Japanese Tissue is lighter than silkspan and polyspan and I'll bet most if not all plastic coverings. It will be done.

>One thing that will help in keeping down the weight is the
>total lack or need for dope. Just cover it. No fuel
>residue, no nitro, no need for dope. Japanese Tissue is
>lighter than silkspan and polyspan and I'll bet most if not
>all plastic coverings. It will be done.

Not to mention all the new very lightweight iron-on tissue-like products for park flyers. Claimed to be as light or lighter than Japanese tissue, with iron on convenience.

My personal prejudice is that a very garden variety "Speed 400" type motor and battery in an ARF Flite Streak would provide fun, sport performance. Make hatch in the wing center section for the batteries, or possibly strap them to the fuselage where the fuel tank would go. I'm sure there must be a simple, off the shelf combination that would provide reasonable fun-flying, but I'm not an electric expert. The real holy grail is a simple system for motor ON/OF from the circle center. Look Ma, no stooge! Z-tron could be used, or how about a real electronic speed control with the signal from a cheap RC transmitter for throttle control transmitted down the lines (recent Model Aviation article). Or a simple relay energized with a battery connected to the lines with a switch (push button on the handle?). Alas, both the later require insulated lines, which add a lot of drag.

Iskandar's suggestion of taking a park flyer power system and building a really light little model for indoors sounds like a lot of fun too. Given the hot indoor electric scene here in the Detroit area, this could be a real possibility. The Oakland Yard faciltiy where they held the first Indoor RC Electric champs (recent Flying Models and Model Aviation articles) is nearby in Pontiac. I'll have to check it out...

Andy

In some cases, no need for covering even. If you use the 1/4" Depron or Fan-fold foam, just use marker pens on it for color. I've seen something similar being sold commercially made out of cut beaded foam. Same deal - color with markers, no covering.

But that solar panels reminded me when I saw CO2 engines first time I did one small model for that engine with only flat balsa wing and elevator and I flew it in gymnastic hall on our high school.

>But that solar panels reminded me when I saw CO2 engines
>first time I did one small model for that engine with only
>flat balsa wing and elevator and I flew it in gymnastic hall
>on our high school.

Hoo boy! I was just given two Modela CO2 motors for free, and I have a third lying around. Not very good free flight motors, but this gives me an idea.....

Andy

It WAS Modela CO2

posts 2-12-18- Yes,you have presented a good case!!!Good summary on 55. All of you keep it up!!! NO, I might not be in the reality world,but all of you are beginning to put up some real good posts--keep it up and lets see some results of a serious flying stunt airplane with in a year. (engine-motor, sorry, I couldn't help it) I'm out of here,keep it up!!!

Here's an idea. Wireless c/l! The whole world is going wireless, why not us? Get a transmitter shaped like c/l handle, install all the c/l stuff into the model and fly it around in circles doing the c/l pattern. Wireless c/l!(Be sure to take offense when somebody calls it r/c). Ha!
Fernando

>Here's an idea. Wireless c/l! The whole world is going
>wireless, why not us? Get a transmitter shaped like c/l
>handle, install all the c/l stuff into the model and fly it
>around in circles doing the c/l pattern. Wireless c/l!(Be
>sure to take offense when somebody calls it r/c). Ha!
>Fernando

Well, what you can do, and it sounds like fun to me, is fly RTP ('Round the Pole) using a 2 channel RC set. Set up a pylon to tether your model with a single line. Just a heavy weighted base, some sort of pole or pipe for a pylon, and a single wire running to an attachment on the wing tip. There has to be a simple bearing at the pole top to allow the tether to rotate freely around it. Rig the model with elevator and throttle. I'm thinking electric here, so use an electronic motor speed control to control the throttle. Stand outside the circle and stunt away. You can take off, land, loop, fly inverted. In *principle* it can do what a control line model can do, but I expect it would be challenging (and hence fun) to get good at flying such a beast. Great for small spaces. Think back yard or indoors. I bet you could try this with a cheapo park flyer and a minimum of fuss and modification.

It's not exactly wireless, and it's not exactly Control Line, but it is sorta like both...

Andy

There have been a couple of articles in Aircraft Modeller International; one on tethered RC and another on RTP using radio to control the elevator. I could dig them out if anyone is really interested.

Andy:
While my post was a joke, it has been turned into a revelation by you.
A tether is a good idea. However,It should be connected from the airplane to a handle held by the pilot. A small two channel transmitter, or similar devise like you mention, should be connected to it. Not wireless but rc/cl.
fernando:+

This is one of the most stimulating threads for some time.
There is no doubt that electric c/l would attract a lot of youngsters to the sport itself, given the advantages of low noise, no oil, instant starting and so on.
It is very important not to compare performance with past levels. When the first OS 60 Four-stroke came out it was immediately criticised for not having a performance comparable to normal 2-stroke .60s, but once modellers used the available power in appropriate models we all thought it was a great engine.
Here's my scenario for an electric c/l model which combines up-to-date technology with practicality:
*the model would be ARF, very light and no larger than 750mm span.
*it would look like the typical fun fly models in use today and be powered with an efficient electric motor and a battery system giving say 5 min duration.
*it would contain an R/C system with one servo on elevator and an electronic speed controller.
* the model itself would be attached to the handle with a single lightweight line probably no longer than 15m and made from a non-conductive material for safety reasons.
*the handle would contain a low-powered Tx with a gyro-stabilised gymbal. Tilting the handle as we normally do would give elevator control and both neutral and sensitivity would be adjustable from the handle. A thumb operated slider would give motor control.

I grew up with IC engines. I build them. I fly them. I love them.
But we have to move with the times and the times are changing rapidly.
We will never attract youngsters in any numbers to the old ways of doing things, no matter how much we may cherish them.

cheers and best wishes for a Happy Christmas

Dave Owen

>*it would contain an R/C system with one servo on elevator
>and an electronic speed controller.
>* the model itself would be attached to the handle with a
>single lightweight line probably no longer than 15m and made
>from a non-conductive material for safety reasons.
Here's a way out thought. I'm not certain this is possible but if you use 2 lines you just might be able to rig up some mechanical contrivance to control the elevator and save yourself the cost of the R/C equipment .

Sorry , but seriously, I like most those ideas but I think we're better staying away from the cost, licensing, frequency control etc issues that radios bring. Most C/L models now fly with no throttle and it's easy to arrange for an electric motor to do that. If you really need a remote motor switch or throttle IR is cheap and easy (I have a switch which uses an old TV remote control, you can't get much cheaper).

LAST EDITED ON Dec-04-03 AT 12:08 PM (CST)
 
>Andy:
>While my post was a joke, it has been turned into a
>revelation by you.
>A tether is a good idea. However,It should be connected from
>the airplane to a handle held by the pilot. A small two
>channel transmitter, or similar devise like you mention,
>should be connected to it. Not wireless but rc/cl.
>fernando:+

Well, if you transmit the signals to the receiver down the wire and don't radiate then it is control line. And this is to be preferred, since you have all the issues of frequency control etc. for "regular" RC if you broadcast the signal from the transmitter. As a practical matter, the "RC control line model" with the TX actually transmitting would work fine, just causes complications if operated at an RC flying field. Of course if you follow the frequency control regulations and obtain the frequency pin to fly, you are no different from any other RC flyer from an operational standpoint. So as far as I'm concerned, it would be OK.

A more interesting point that you've raised is the use of *monowire* to a handle. The usual problem with transmitting signals to a receiver via the wires is that they have to be insulated, resulting in a much larger effective wire diameter and much extra drag. But a single wire could eliminate this problem. If an input scheme could be developed to translate the handle angle into elevator servo movement, then you would indeed have a nifty CL setup, with a trigger or slide throttle on the handle. Way cool, and only the drag of *one* wire. Super neat for electric power. What is required is that the handle rotation turn a pot for the control input. A grip which rotated in a fixed handle frame would do this... or hack the TX stick into the handle and push/pull the stick with the thumb. A trigger throttle would work the best for this. How about a pistol grip car radio for the handle? Handle and trigger throttle already made. Now just figure a nice way to rotate the "steering wheel" for elevator control. Heck, you could fly with two hands to start and just turn the knob with the left hand! Better to develop a one-handed system though. Oh yes, include the moral equivalent of a fishing swivel in the line so that loops don't twist up the wire.

Fun Stuff!

Andy

Edit:

I Wrote:

"Now just figure a nice way to rotate the "steering wheel" for elevator control."

Solution: Attach the wire to the wheel. The wheel orientation is held approximately fixed by the tension in the wire. Now rotating the transmitter in the manner of a standard handle rotates the pot shaft for elevator control. The mechanical integrity of the steering wheel must now be sufficient to bear the tension in the wire, so this will only work for smaller models. But a more mechanically robust version could easily be made. Mecahnically, this is the concept for a generic control handle which will rotate a pot shaft. Attach the wire to a wheel which drives a shaft with axis normal to the handle. The shaft turns the elevator control pot. Simple. And all the required components could be hacked from a pistol grip 2 ch radio.

AT

LAST EDITED ON Dec-03-03 AT 10:50 PM (CST)
 
>Here's an idea. Wireless c/l! The whole world is going wireless,
>why not us?

I just got my amateur radio license, KC9FAC, so I am a
licensed "wireless operator." Hmmmm......do I have
to remove the wires from my ARF Nobler?

Feasible electric CL is here. Talk to Mike Palko. Feasible means 4-5 min flights with Fox 35 performance.

Brushless outrunner motor AVI or similar 5 oz. $80
10-12 NiMh cells pulling ~20 amps 250W 15 oz. $40
Car RC rig for speed control 1oz $40
Nice light airplane(no heavy motor mounts) 12 oz.,
Total 33 oz.

The brushless motors run like a household fan motor, constant speed. As the plane maneuvers, the motor draws more current but keeps its speed.

Problem areas- the best NiMh cells are C cells which weigh ~55 gr. and have more capacity than you need for a 5 min flight. A 12 cell pack would weigh about 24 oz. so the plane would be a little heavy for its size. But you could just go to a high aspect ratio to keep the performance up. Sport CL needs the same performance in a sub C cell to keep the weight down.

LiPoly cells are great on paper- about half the weight of NiMh, but costly. Currently you would need 8 of them in a 2x4 arrangement to give 14 volts and adequate capacity without pulling too much current. 8 would cost in the range of $240. They still are pretty fragile and errors in charging or pulling to much current destroy them.

>Feasible electric CL is here. Talk to Mike Palko. Feasible
>means 4-5 min flights with Fox 35 performance.
>
>Brushless outrunner motor AVI or similar 5 oz. $80
>10-12 NiMh cells pulling ~20 amps 250W 15 oz. $40
>Car RC rig for speed control 1oz $40
>Nice light airplane(no heavy motor mounts) 12 oz.,
>Total 33 oz.
>
>The brushless motors run like a household fan motor,
>constant speed. As the plane maneuvers, the motor draws
>more current but keeps its speed.
>
>Problem areas- the best NiMh cells are C cells which weigh
>~55 gr. and have more capacity than you need for a 5 min
>flight. A 12 cell pack would weigh about 24 oz. so the
>plane would be a little heavy for its size. But you could
>just go to a high aspect ratio to keep the performance up.
>Sport CL needs the same performance in a sub C cell to keep
>the weight down.
>
>LiPoly cells are great on paper- about half the weight of
>NiMh, but costly. Currently you would need 8 of them in a
>2x4 arrangement to give 14 volts and adequate capacity
>without pulling too much current. 8 would cost in the range
>of $240. They still are pretty fragile and errors in
>charging or pulling to much current destroy them.

I could be wrong, but my memory says the problem here isn't in us talking to Mike, but he doesn't want to (or hesitates to) talk to us.

Why an RC car speed controller and how is it actuated? I had assumed the model would not fly much beyond 6:30 or 7:00 and so would simply drain the batteries and land.

Or if the motor is merely stopped and started with the speed control, is it practical to have the Pit Dude flip a switch and then depend upon a timer to shut the power off?

There was mention earlier of frequencies and licensing. This problem can easily be worked around with 100-watt transmitters operating on the 27mHz band and (I think) 53 mHz. Those teeny little RC cars which showed up last year right before Christmas are an example of legitimate operation of an RC vehicle with no licensing requirements.

>This problem can easily be worked around with 100-watt transmitters
>operating on the 27mHz band and (I think) 53 mHz.

27mhz (11 meters) lies right below the CB band and
is prone to interference from CB'ers running illegal
linear amplifiers with lots of splatter, as well
as those who operate illegally outside of the CB
channels, the so-called freebanders.

53mhz (6 meters) requires an amateur radio license.

>
>There was mention earlier of frequencies and licensing. This
>problem can easily be worked around with 100-watt
>transmitters operating on the 27mHz band and (I think) 53
>mHz. Those teeny little RC cars which showed up last year
>right before Christmas are an example of legitimate
>operation of an RC vehicle with no licensing requirements.
>
>
> Dan

Dan,

That would be 100 *milliwatts* I think. A 100 *watt* transmitter would certainly speak with authority, but would have some definite licensing issues .

Good point otherwise--many click-click radios from toys could do motor on-off. One caveat: the real cheapies use super-regenerative receivers. As such, they will go off with *any* 27 Mhz signal, including but not limited to CB radios, which broadcast at 5 Watts, and therefore pose a threat at some distance.

I would also look at TV remotes and automotive keyless entry systems. The Z-Tron provides similar functionality to these and actually is competitively priced. I've looked to hack such systems for turning bubble machines on-off at a distance, and it is actually pretty to hard to find something that will work and is not too pricey. A cheap 2 ch RC set would work great, but there goes the old frequency control bugaboo again.

Chalk up another $0.02...

Andy

I think Dan has the right idea here. The pit man turns the steady rpm motor on (brushless)& launches. You fly the pattern and then the free flight timer, tick off, stops the motor by allowing an on/off switch to be activated via a spring. Free flight dethermalising timers normally go for 6 minutes, but adapter plates can make them go up to 8 minutes, so this is feasable and they weigh about 1/2 oz.

I know on some electric speed controls with Battery Eliminator Circuitry (BEC), there is a battery monitor which shuts down the motor when the battery hits a certain level. This is there when the motor battery is also used for the receiver battery, and so of course you don't want to drain the battery so low that the receiver stops working.

The problem with this is that you are still at the mercy of the battery, as this cutoff would depend upon its age, how charged up (or how long since it was last charged). On the other hand this is roughly equivalent to figuring how much fuel to use for a glow engine (although a tougher solution to figure out I think)

Don't ask me why, but for some reason I prefer a non- "wireless" solution to the motor (same for our normal glow engines--even if wireless is allowed under current rules ). That makes the challenge which is what I find so appealing about CL.

Dan,

That would be 100 *milliwatts* I think. A 100 *watt* transmitter would certainly speak with authority, but would have some definite licensing issues .

Thanks, Andy. I believe you have identified one of the major reasons I no longer fly much RC.

LAST EDITED ON Dec-04-03 AT 09:57 PM (CST)
 
RTP flying is (or was) pretty big in the UK - I've seen articles about it, even construction articles. You can even stunt them, in a fashion (set them up to fly level at half throttle and loop at full throttle) and you can fly them two in a circle.

I found this web site yesterday that would be really useful for indoor electric CL. Really inexpensive and easy, lots of data about batteries and motors.

http://www.foamyfactory.com

And then I came across this:

http://www.aeromicro.com/index.htm

The possible variations when it comes to motors and props literally boggles the mind. I don't even know where to start.

One of the IMAA RC guys showed me a video of a "3-D Park Flyer" model. It was about the size of a Flite Streak Jr, maybe a little bigger, and with a full fuse. It looked like an Extra 300 or something, and it was electric powered.

It would hover. Go up. Go down. The pilot controlled as if it were a winged yo-yo. For minutes and minutes. Just like some .91 powered monster RC ship.

For CL, the time is approaching. Someone out there with cajones, imagination, and a large fortune can turn his investment into a small fortune.

Some day, we all will be going the Electric Route. Separate 'Lectric events, with AMA blessing. I opine this, anyway...

But I am going to miss the smell of methanol in the morning, the 9K band hearing loss, the five stitches that you regularly get for your flipping finger, the Wind Chill Factor of Superfuel on your hands when it is 32F out there, the backfire flames cooking your paint job, and you didn't see it right off...

>I found this web site yesterday that would be really useful
>for indoor electric CL. Really inexpensive and easy, lots of
>data about batteries and motors.
>
>http://www.foamyfactory.com
>
>And then I came across this:
>
>http://www.aeromicro.com/index.htm
>
>The possible variations when it comes to motors and props
>literally boggles the mind. I don't even know where to
>start.

Isky,

Jackpot! The little foam jobs look just like typical Sarpolous profile jobs, only in foam. Leave off the radio and substitue a bell crank. Go fly. Way cool.

Andy

One little bugaboo I'm thinking about is the one about the speed controller (as mentioned earlier). One thing you DON'T want is to have to fly around for minutes on less and less power as the battery winds down, to the point where it has to land .. and then it breaks the prop or worse.

I could probably design a circuit using a MOSFET to do the switching - no need to oscillate it, since we just need full throttle, just make it turn on or off - controlled, perhaps, by a long probe and microswitch under the plane, so it switches off when the probe gets bent upwards. Or you could build something with a 555 timer chip where you leak a large capacitor through a resistor, and when the 555 output switches, the MOSFET is turned off. There's a circuit like that in my latest Flying Models. Momentary switch to charge the capacitor, which also turns on the motor.

I see these lightweight Depron airplane being flown mostly indoors, and I don't see why one can't fly the entire pattern with one, given that the batteries on these RC 3D park fliers seem to run for a good 5-7 minutes. They'd be light enough to fly on heavy sewing thread, or very light Spectra fishing line. Use a large enough bellcrank (1/16" ply) and you can use a largish handle.

>I could probably design a circuit using a MOSFET to do the
>switching - no need to oscillate it, since we just need full
>throttle, just make it turn on or off - controlled, perhaps,
>by a long probe and microswitch under the plane, so it
>switches off when the probe gets bent upwards. Or you could
>build something with a 555 timer chip where you leak a large
>capacitor through a resistor, and when the 555 output
>switches, the MOSFET is turned off. There's a circuit like
>that in my latest Flying Models. Momentary switch to charge
>the capacitor, which also turns on the motor.
>
In my time I've done both of those. There are circuits for them in various posts in the (very quiet) Electric Control Line Forum at www.rcgroups.com (look under Trial Forums). Even simpler is to use a relay. The relay drops out and shuts off the motor as the voltage in the pack reduces. Again there are examples in that forum

I now mainly use a simple infra red on-off switch which is ideal if you're flying on your own. No need for stooges, walk to the centre, pick up handle, switch on motor, get bored, dizzy or notice power is dropping, switch off motor . I have 2 versions, one for brushed motors which just directly switches a MOSFET and the other for use with ESCs and brushless which switches an oscillator simulating a "full throttle" signal but I haven't drawn them up properly yet. Let me know if there's any interest.

All of these are fine for experimenting but what we really need is for someone like GWS to produce an ARF including whatever control is needed. I think that's the only way C/L will really get a lot more attention.

>I now mainly use a simple infra red on-off switch which is
>ideal if you're flying on your own. No need for stooges,
>walk to the centre, pick up handle, switch on motor, get
>bored, dizzy or notice power is dropping, switch off motor
>. I have 2 versions, one for brushed motors which just
>directly switches a MOSFET and the other for use with ESCs
>and brushless which switches an oscillator simulating a
>"full throttle" signal but I haven't drawn them up properly
>yet. Let me know if there's any interest.
>

There is a great deal of interest! Please publish them somewhere.

Thanks,

Andy

LAST EDITED ON Dec-09-03 AT 09:58 PM (CST)
 
Here's one:

http://www.rcgroups.com/forums/attachment.php?s=1e5b8ddfe8f9d6c1cc66ef32248a1d58&postid=162788

and another one:

http://ijcooper.20m.com/Hobby/autodischarger.htm

(this one seems to be a battery dump, but it should be adaptable for use as a motor cutoff.)

AMA CLPA rule 2. Model Requirements and Contestant Classification. Engines shall be of the reciprocating internal combustion type or of the jet type. In other words, ELECTRIC MOTORS ARE ILLEGAL IN PRECISION AEROBATICS. THIS APPLIES TO THE PAMPA CLASSES AS WELL! This rule is stupid and obsolete and needs to be changed.

Electric, 3.4 event 608. This is your electric PA event. The pattern is the same. This needs to be looked at carefully as the engine and battery specifications are clearly obsolete (I should say probably obsolete, because I don't really know.)

Perhaps the biggest barrier? At least one electric stunter exists which can fly the AMA pattern competitively with wet engines. So any thinking about a modified pattern, or lack of performance potential, is just dwelling in the past, and being behind the curve, so 20th Century.

>Here's one:
>
>http://www.rcgroups.com/forums/attachment.php?s=1e5b8ddfe8f9d6c1cc66ef32248a1d58&postid=162788
>
>and another one:
>
>http://ijcooper.20m.com/Hobby/autodischarger.htm
>
>(this one seems to be a battery dump, but it should be
>adaptable for use as a motor cutoff.)

Isky,

Motor cutoffs are all well and good, but I want the infrared on/off *command* unit. I'll bet it can be hacked together out of Radio Shack stuff...

Thanks for passing this along...

Andy

Cy's first statement--
"Inquiring minds want to stimulate the engineering debate"
Fellows we have some real good imput in the last 4 posts--Lets continue! Thank you Steve for your post on 51--Jim T , Thanks for telling us the Event 608 Elect 3.4 (I did'nt know) and telling to NOT go back to a"modified pattern" Look forward!! Andy for your idea of the infra red, motor shut down with infra red (instead of a signal down the lines--Which could be good--But the infra could be so simple. I know, I'm reviewing, but we are moving right along with this.
On the post that Paul (thanks) put on in 49 he showed us the model and the info. Not to be degrading but as I talked to (other brother Dave) at the hobby shop this morning he indicated that this set up is really 12 year old technoligy. The motor setup is 9 oz. the battery pack is 13 oz and a llx8 prop!!!! All of this is working against each other. NOW, I have not seen this posted here yet but as we went thru a Hobby-Lobby cat. The technoligy (sp) is really here NOW. Take for example he showed me the PJS 3D -1000 brushless rotating can motor. 3 oz weight!!!!! $180.00--spins an 11x5 prop on 8 cells - Nicad - at 25 amps and 35 oz thrust and this will pull a 5 # airplane. Check out the www/Hobby-Lobby.com site and see the possibilites!!!
Lets think out side the bun--uhh--box.

OK, I will put some thoughts I actually try to convert to reality. The new FAI rules are going to allow electric power. I am thinking to do serious stunter with 300W power train.

1/ The PJS engines does not look very good, as they have large rotating magnet and it will bring extra gyro torque (I note the weight 85g is as far as I know without alu mounting pad). I am better concentrating to Jeti Phasor engine 30-3. The weight is 220g (<8 oz) and will twist 11x4 prop at 10 000rpm. It will give >300W at ~10-12V what is really useful value.

2/ Nicd or NiMh batteries are out of sense for competitive flying as the battery for 300W power train is at 600g (22 Oz). So the only really useful way is LiPoly 3 cell battery. The problem is, there are not 10C full time high capacity cells yet, so the capacity must be designed higher. For example the Kokam cell 1500mAh is able to give 10A. So it will really and usefully give only 1000mAh. For 30A current we need 3 cells parallel, so good choice is 3s3p 1500mAh kokam battery. It will come at half that weight. The same calculation can be done for any other type. Kokam makes one very good small cell with continuous discharge 20C!!! But it is only 360mAh, but can be useful for small models with 280 type engines at 3A.

3/ The controller for brushless engine will need self-regulation to bring contiguous power delivery independent on battery condition. I am in contact to Jeti regulator producer and I am trying to implement such a feature to the actual microcontroller version of regulator. It will have that self regulation (allowed by FAI rules) and timer for 6 minutes (also allowed by FAI rules). So the operation is: connect battery, come to start, push a button, engine starts, fly 6 minutes at constant speed and land with a fraction of capacity still in the battery. That mode is very compatible with Lixx batteries. They do not like very deep discharging and they do not have memory effect, so partial discharging is not anything wrong. On opposite side there is something called “quick charge”. It is charging method using higher than 1C charging current, but the charge is cut off before full capacity. The 2C quick charge will take ~15-20min and stops at ~80% of capacity. So you can fill it full home before flight session and on field use quick charge and so convergate to 0% capacity at end of session.

I will certainly put some more info when I finish something real.