recommendations of "what works"

[gponder]

Been reading the posts here about electric control line for a couple months. Great stuff! The recent info on low-voltage cut-off relays is outstanding. Which leaves some details that need addressing so I can maximize my chances for success.

Goal: c/l trainer for first flights and beginning aerobatics

Assumptions: speed 400, 8 cells
decent building skills
(free flighter with a
gram scale)

Questions:
What mah rating for cells? Are any brands better than others?

Line length, and diameter?

What prop, assuming direct drive? Brand recommendation?

Are all speed 400s the same, or are some brands better than others?

What is target weight of airplane with and without cells and motor?

Very Important: Recommendations of kits or plans to use. Assuming that I'm converting a glow-powered kit or plan to electric, what are recommended mods for saving weight. ie, do I sand the ribs a little thinner, or just go ahead and use balsa that's only half as thick to begin with. Since there's no glow fuel, do you still use dope, or just water shrink the tissue. (For this model, we're ignoring appearance completely.)

Hope I've not broken any rules on my first post. Thanks in advance for your time and sharing your experience.

glenn

[jrb]

Might be difficult to get a 100% "what works" answer here as this is fairly new ground.

A few tid bits:

All S400s are not equal. 1st there are 2 main types: 6 volt & 7.2 volt. The 7.2 volt are a little less common and are typically used with 10 cells and a gearbox to swing an 8 to 9 inch prop. There are many 6 volt class of S400s -- hse are most often used with 8 cells direct driving 5 to 6 inch props.

Some common 6 volt S400s are: Graupner, Zagi, Multiplex, & Wattage 370. The work well with 8x500A (or AR) cells and the Gunther "push on" prop (stock prop w/Zagi & Wingo).

A bit lighter duty would be with 8x650 AAA NiMh and the Wattage 5x2.5 prop.

I think (if its still available) the Carl Goldberg Stuntman 23 and a Gunther S400 system using the cut-off relay would do you well.

[Bare]

Am I to understand that you wish to build a s400 powered control line model... and.. do aerobatics?? I don't believe that there is nearly enough power available to;
a) fly in a circle towing control lines
b) fly straight and level let alone loops
If you've flown cl before you would know that with Glow engines one must go up an engine class size (or 2) compared to RC due to the serious powewr requirements inherent in dragging flying lines around a circle.
perhaps you should think more along the lines of a mid sized brushless motor and 14 to 20 cells as a starting point.

[DICKEYBIRD]

Hey Bare,

Go back to 4/25 in this Forum and read all of the Mike Gretz "motor cutoff" thread on his S400 U/C plane. He seems to have done great with a 400 motor!

Please don't kill my dream of a cheap electric ukie!

[mdgretz]

Bare,
At the risk of being repetitive, I'll repost some earlier info. I am presently flying a C/L model using a Speed 400. And it flies very well!

Here are the specs:
Speed 400 (7.2v)
direct drive turning a 6x3 Cox (gray) prop
(8) 500mah nicads (onboard airplane)
.008 x 30' steel control lines
Wingspan 27"
Airfoil: NACA0015 (full symetrical)
Wing Area 241 sq.in.
Wing Loading w/8 cell,500mah battery pack is 6.7 oz/sq.ft. (a standard SIG 1/2A SKYRAY has about the largest wing area of any model of its type. With a Cox Black Widow .049, it has a wing loading of 7.2oz/sq.ft. -- so I've beat that with this electric airplane!)

Delta configuration. Battery pack fits inside root of right wing. Here's a link to a couple pics of my airplane. http://showcase.netins.net/web/mdgretz/

Inside and outside loops, inverted flight, figure 8s, etc. are not problem for this airplane. Next step is to try a 8-cell 500mah nickel metal hydride pack which will save some more weight. I know there are better motors out there that will provide the same of even a little more power AND weigh less, but what I'm trying to do is build a fully aerobatic model that uses the cheapest stuff out there. So far I've been very pleased with the result.

[Bare]

Well.. IF what you claim is correct then I stand amazed. I've been flying CL (on and off ) for over 40 yrs, and still fly Combat whenever I can get enough models built for the Demolition Derby called a contest.
I've been using s400's since '96 and am simply amazed that you can get a 400 and it's battery pack to fly a circle let alone do any sort of stunts, although I suspect that your idea of aerobatics may be a bit different than that of an old combat flier:-)
I've witnessed bold attempts at CL with Astro Cobalt 15's turn into embarassing events , so you will have to bear my scepticism..
Anyhow, perhaps I will try for myself what previously seemed patently obvious as truly unworkable.

[steve lewin]

Now, now Bare. It's not really very polite to imply that people are lying about their achievements.

I agree we need to consider the level of aerobatics. I see no reason why a lightly built S400 plane can't do wingovers, loops, basic eights etc. and I hope to prove that myself soon. I don't think we're talking about much in the way of square manouvers or my old combat wing standard of overhead eights until the fuel runs out. The average combat wing is built like a brick, with the aerodynamics of a truck and then seriously overpowered. We can't easily do that with electrics, we have to use a little finesse instead.

BTW if you read Stunt News you'll know that people can and have built electric stunters which can fly the complete AMA schedule. However these are a lot bigger and more expensive than S400 models.

Steve

[DICKEYBIRD]

Hey Bare, I hate to toot someone else's horn for them, but....you do know who Mike Gretz is, doncha? He probly knows about that which he speaks.

[mdgretz]

Hey Dickeybird,
When it comes to electric powered control line flying, I'm just as green as the next guy. This is my first attempt. But it's been so interesting that I think I'll build a couple more. This one has actually raised more questions than I had initially. There sure are a LOT of things you can tinker with to change the performance of an electric model!!!

[DICKEYBIRD]

Hi Mike,

I was referring to your general experience in the world of round & round type aircraft; that's worth a ton! Plus, I'm just trying to stir up all you guys and get the creative, competitive juices flowing. Me being a lazy scoundrel, I'm planning on you experts coming up with a great flying, simple ukie that'll amaze us all using a cheepo motor and $3.00 worth of R/Shack bits! http://www.ezonemag.com/disc/wink.gif (...and Sig wood of course!)

[dr.E]

Hey Mike!! I stumbled on a couple of valid designs.

The first two are by Claus Maikis:

VOLTTIMER (Aeromodeler sep 93)
AMPTY (April 96)


And the finelly tuned WATTS-ON by Jan Odeyn. This one was also featured as a construction article on Aeromodeler.

The ESC that seems to work well is the one designed by Jean-Michel Fraise and published in Looping Mag.
I'm in the process of obtaining the original pubs.

[mdgretz]

Sounds like interesting reading. I don't have any of those magazines. Anybody know where to get back issues? By the way, what's "Looping" magazine?

[steve lewin]

Unfortunately Aeromodeller magazine (UK-based) has just been sold by Nexus Publications to another company. I don't know what the situation is for back copies but I wouldn't think it's good. Another problem is that all of those plans have been discontinued for some time (I tried to get copies).

The issue numbers are useful though. I think I'll try some the UK based forums to see if anyone has copies they could spare.

Meanwhile I'm sure that there has been at least one ECL model published in Stunt News (the PAMPA magazine). Anyone know ?

Steve

[Dereck]

Ref those "Aeromodeller" issues, I think I have one with a simple S400 CL model in it. If memory serves, it was a sort of flying wing a little like a Sig "Wonder" in planform.

If anyone is desperate, drop me a line on direct and talk me into finding the article and photocopying it for them. I recall the model using a Mini-Olympus gearbox and 7 or 8 cells. A bendy prop is always a real good idea here too.

I recall that the electric CL feature ran for months, produced one usable plan (and I aren't sure if its full size, or you get to use your programmable copier a lot) and was something of a cure for insomnia.

Back issues - last I saw the Aeromodeller archives, they were at the last offices of Argus, just before Nexus bought them out and trashed Argus. They had one copy of every AM ever in a bookcase back of one editor's desk.

No idea what happened to them, but maybe Alec Gee, newly at Model Activity Press, might know. There must be other complete collections in private hands, but none I know of.

Regards

Dereck

[dr.E]

I have some of the articles as well as the esc plan.