Author Topic: Buiding for electric (Read 3219 times)

Will Moore · « **on:** November 28, 2006, 06:56:20 PM »

How far can we push the envelope in building with electric in mind ?

Should we still use thick airfoils ? We do not need them to slow the airplane down,
as electric motors do not tend to wind up in manuevers. We do need lift, however,
but what if we built light - like free flight light - like 660 sq. ft. wing area ship
ready for power train weighing in at about 20-25oz. Would we still need thick airfoil
and large motor e.g. AXI 40 series or Plettenburg 30 series.

An axi 2826 @ 18 volts can easily swing a 12/6, 13/6 prop and develope 600+watts
using a 5 cell, 18 volt battery.

What are your design ideas for such a size 60 ship ?

frank carlisle · « **Reply #1 on:** November 29, 2006, 06:51:58 AM »

Hi Will,
I'm not a designer or innovative guy, so I won't be pushing the envelope for electric stunt design. I do see an opportunity to use the electric system I have in my ARF Smoothie to produce a cool model or two though.

My first choice would be to build the RSM Fierce Arrow kit and set it up for e-power. With 900 plus squares it should caarry rhe weight of the batteries with no problem.

I also have a set of Dick Sarpolous plans for a Fokker D-23, which is a push-pull gesign. It calls for a .35 engine on the nose and a .15 in the back. Wing is about the same area as the Smoothie or Nobler.

While miether one is going to revolutionize electric stunt, either one would be a cool model to take to the circle.

Dean Pappas · « **Reply #2 on:** November 29, 2006, 01:27:40 PM »

Hi Will,
I do think that some future airframes will be tailored for E-power.
Personally, I think that big flaps (think drag brakes in the corner) will shrink, but I could be wrong!
I'm thinking flapless and big wing.
The RPM governor will take care of speed in the corners, for those who use it, while those who don't will probably still want normal sized flaps. Mostly, I anticipate designers to find ways to take advantage of the lessened pitch moments of inertia. A plane that resists atarting and stopping cornering forces you to trim for more stability and possibly less performance.
By the way, I am pretty sure that 600Watts on an AXI 2826 series motor will eventually cook it, but I'd love to be proven wrong on that one. Let us know how long yours lasts, at that power!
best regards,
Dean Pappas

frank carlisle · « **Reply #3 on:** November 30, 2006, 07:05:50 AM »

Seems like everytime there is talk of electric control line it always leads toward building a highly competitive worldbeater of a stunt ship. Now we're talking building a 60 inch airplane that weighs 25 oz. And we talk about how fast everything is evolving.
I've been reading threads about electrics for over a year now and I haven't seen any new stuff. Motor, betteries and timers are all the sme as they were last year. All this talk of new equipment on the horizon has most guys sitting on their thumbs and waiting for that hi tech 25 0z. monster stunter. They aren't going to get into it until it's fully developed.
As far I'm concerned electric is developed enough right now for the average guy to get into and his money and gear won't be wasted or become obscelete. My electric Smoothy has been flying the pattern for me since last January. Other than the initial start up cost the plane hasn't cost me a cent. And it still works as well as it did a year ago. Technology hasn't passed it up.
Currently I'm looking at plans and deciding what my next electric model will be. There is a push-pull design that looks interesting, and a canard and a flying wing.
I believe that if the emphasis was on putting together a cool sport/stunt model we'd see a lot more electrics out there.
What we need more than anything is a sure fire electric plane that everyone can afford. Electrics should be as easy to understand as glow. I would like to see us come up with nomenclature that says. This plane takes that motor and that battery. As soon as the endless variables are condensed down to this plane that motor we'll see more guys trying it.

Walter Hicks · « **Reply #4 on:** November 30, 2006, 05:45:24 PM »

Hi Everyone ,

I have plans to a .60 sized stunter Called Stuntfire by Scott Bair.

It is built a lot like a FF stick plane and was very light even with a ST .60

a little over 50 oz I believe. I think this would be a great electric project .

I would use an E Flite 46 for this one ! Any thoughts W Hicks

frank carlisle · « **Reply #5 on:** November 30, 2006, 06:01:15 PM »

The Stuntfire was mentioned once before as a possible candidate for electric.
The plans were published in one of the modeling mags I believe.

Will Moore · « **Reply #6 on:** November 30, 2006, 09:22:24 PM »

Where can I get the plans for this model - does anyone have any pictures ?

Walter Hicks · « **Reply #7 on:** November 30, 2006, 10:35:56 PM »

Will,

Model Aviation publishes the plans, or if you are in a hurry I will send them to you.

Let me know AI would be glad to let you borrow them to take a look ,WHicks

Rudy Taube · « **Reply #8 on:** December 02, 2006, 01:01:57 PM »

Hi Walter,

Do you have the year/month of the issue this plane was in? It will help us order the plans and construction article from AMA. ... TIA :-)

Dean Pappas · « **Reply #9 on:** December 02, 2006, 02:06:43 PM »

Hi All,
Hi Frank,
You are absolutely right Frank, and if I'd thought it would take this long to get a really nice timer to market, I'd have shut my mouth a long time ago.

In the meanwhile, the existing stuff is really completely Sport-flying worthy, and all that remains is to write the detailed "how-to".

Message understood!
later, friends ...
Dean

frank carlisle · « **Reply #10 on:** December 02, 2006, 02:25:21 PM »

Thanks Dean hor the affirmation.
Please check out my thread here on the push-pull and add your recommendation as per props.

phil c · « **Reply #11 on:** December 02, 2006, 03:19:46 PM »

You have to ask what envelope are you pushing, and what for? For stunt the name of the game is controllability. Anything you can do to make the plane steadier, more predictable, and have more uniform response all around the circle is better. To me that means using the governor, possibly with a speed sensor, to keep the airspeed as uniform as possible. Finding the "right" moment of inertia. From combat I can tell you that less MOI isn't necessarily better. Bigger stabs. Maybe a useable flying stab design with an adjustable counterbalance/hinge location for more precise control trimming. If you can figure out how to fly an electric at 40 mph with about 10 lb. of line tension, that would be a big help. Big, lightly loaded wings won't make it, not until the scoring changes. They get bounced around by gusts too much. A moderately loaded, highly tapered, very thick wing may do the trick. It has reduced gust sensitivity and enough lift to handle the wing loading.

Will Moore · « **Reply #12 on:** December 02, 2006, 05:30:10 PM »

Phil;

Thanks for thqt comment - that answers some questions I had

Will Moore

Dean Pappas · « **Reply #13 on:** December 04, 2006, 11:27:15 AM »

You have a real good point, Phil.
One of the things that always surprised me, no matter how many times I re-learned it, was that more of the "right kind" of horsepower always got a heavier airplane through the pattern. it's sort of like the 4-stroke package: the really well set up ones grunt in the corners better, and the pilot reports come back that, "Even though the plane is now nose-heavy, it turns better!" How many combat ships slow down if you make constant tight maneuvers? All of them! I think that one of our goals is a plane that cannot be slowed down, even very briefly, by cornering hard. Then we won't have to fly artificially fast to keep from falling out of a hard corner. Then we have to deal with the line tension issue, if we want to fly slower. Several folks have messed with vectored thrust, like Wild Bill, and Charles Mackey. Does it work? If not, what were the problems? If fuel delivery was one of the issues, we can solve that one!
later,
Dean

Walter Hicks · « **Reply #14 on:** December 05, 2006, 09:33:55 PM »

Plans for Stuntfire 60 Published in Model Aviation august 1983.

Plan # 416, 62" span wing 670 Squares,

Rudy Taube · « **Reply #15 on:** December 08, 2006, 12:41:42 AM »

Walter,

Thanks for the plans info.

I was able to download the article and the plans (page size) form the AMA Web site. It is in the members digital section.

The construction reminds me of the VERY light, rubber powered, planes my grandfather built when I was a kid. :-) I think they were "Gallow" kits?

Richard Becker · « **Reply #16 on:** December 08, 2006, 02:17:28 AM »

There seem to be several big advantages and potential advantages in electric C/L.

1) No noise. This is an inherent advantage and is why I also recently built an electric Smoothie, which I can fly at a park within walking distance of my home. If I have a glow motor I need to travel 12 miles away! Also no oil trying to soak into everything!

2) I am waiting for someone to come up with a speed controller. I am not an electronic wizard, but I am sure it would be relatively easy to find a small pressure transducer which could measure wind speed, say at the end of a wing out of the prop wash. This means that on downward manoeuvres the motor would slow down, on upward it would speed up, and even as the model circulates from down-wind to into-wind the motor would compensate.

It could also be persuaded by means of a timer to speed up during the duration of the flight as the part of the pattern is reached where a bit of extra speed might help.

3) It could be possible to change the lateral moment of inertia of the model by putting the battery on the C of G. This should make tight turns easier, but may increase the gyroscopic effect of the propeller because of the longer nose moment. I think this would overall be an advantage, though.

Although it is certainly possible to build electric models lighter than glow, because of the smoother and less vibration filled power delivery and no need for fuel proofing, I don't think building too light will help beyond a certain point. The model needs a certain amount of penetration in order to maintain speed in windy conditions and on tight corners. However, it would be interesting to play with this and weight (ballast) could be added or taken away from the CG area to tune the model for different conditions of wind and turbulence.

Dean Pappas · « **Reply #17 on:** December 08, 2006, 11:18:55 AM »

Hi Rich,
It is really quite amazing how good a the RPM governor inside the ESC is already.
If you wanted anything, it would be a line tension or centripetal force switch/ sensor to bump the governed RPM up a hundred or two when needed, but it just ain't needed.
If by some fluke of nature you had a plane that was too light, you'd add battery capacity, and up the running current and prop size for more power.
Still, I see a wet-power assumption has crept into your last post: that weight or momentum is needed to carry you through the high induced drag of the corner. The goal should be light with a power system that can almost instantaneously increase power to cancel out the transient high drag spike, and then immediately settle down as the corner ends. The governor in the Castle Phoenix is adjustable, and we have begun to push the gain and response time as far as we dare, but Winter has interrupted our work. We will be doing experiments in the cold just to learn how to extend the operating range of the system.

This is fun!
later,
Dean

linheart smith · « **Reply #18 on:** December 08, 2006, 01:00:50 PM »

I am glad that I am on board with this electric stuff in the early stages. Always been on the tail end of everything in my life. Like Dean said. "This is fun".

frank carlisle · « **Reply #19 on:** December 08, 2006, 01:11:45 PM »

Quote from: linheart on December 08, 2006, 01:00:50 PM

I am glad that I am on board with this electric stuff in the early stages. Always been on the tail end of everything in my life. Like Dean said. "This is fun".

The motor compartment is very clean and net. Nice work. Can we see the rest of it?

Dean Pappas · « **Reply #20 on:** December 08, 2006, 02:28:37 PM »

Yes, that's too tidy!
all the best,
Dean

Richard Becker · « **Reply #21 on:** December 10, 2006, 11:56:27 PM »

Hi Dean
Thanks for your thoughts, you're right, what we need is a power spike to get through the corners. I recently recieved a beautiful Playboy kit from Bill Sawyer (amazing wood, cutting and detailing) and think I will make this electric.
Please post any advances you find on the battery/controller/motor side that you find as I would like to build these into the PLayboy when I get around to it early next year.
Richard

Bill Sawyer · « **Reply #22 on:** December 28, 2006, 07:58:45 PM »

Richard,
I am working on the idea of using electric in my Playboy and if it works out then I plan to offer the kit with options to use either electric or fuel. I am trying to finish a second run of Playboy kits and some more Argus kits to restock. As soon as those are done my full attention will be toward the electric Playboy. If you get ahead of me in this effort I would appreciate some feedback on your results.

Bill Sawyer

johnstrollo · « **Reply #23 on:** January 01, 2007, 01:57:58 PM »

This is gonna sound dopey, but would someone please give me a list of all that is needed to install, run and maintain an electric C/L model.
I need makers and part numbers, how many, etc.
Sort of a shopping list for a can't fail effort.
I wanna use this to train for speed, so I would like it to be powerful and turn key. Shorter flights, like under a minute run time are desired. I will use short lines to simulate speed of rotation.

I've asked guys for this, but I get ohms and all kinds of stuff that gives me headaches.

Dean Pappas · « **Reply #24 on:** January 01, 2007, 09:03:22 PM »

Hello John,
It's not at all dopey, but let's spin a new thread for this, entitled E-flight equipment.
I'll gather some info, and post in in a few. I invite others to do the same.
later,
Dean

Author Topic: Buiding for electric (Read 3219 times)

Walter Hicks

Walter Hicks

Walter Hicks