Electric Box Car Chief flies

My 60% scale Box car Chief (Box Car Papoose?) flew for the first time today. Power is a 3.5:1 GWS gear drive unit with a 7 x 6 prop turning at 4500 rpm. Power is 6 x 250mAh nicads and flight time around 5 minutes at an all-up weight of 6.3 ounces. I knew it would fly, the question was - could it pull the lines around? On 30 feet of thread lines it took around 1/4 lap to get airborne from short grass. The lines made a large curve and I could only manage mild wingovers. I need thinner lines!


[photo not recovered: bcpf2.jpg]

LAST EDITED ON Feb-12-04 AT 06:10 PM (CDT)
 
"I need thinner lines!"

Naw, you just need more power!

Nice work, tho! Looks great!

Tim

LAST EDITED ON Feb-18-04 AT 06:37 PM (CDT)
 
>My 60% scale Box car Chief (Box Car Papoose?) flew for the
>first time today.

Dave,

You're having entirely too much fun. Bravo!

For some very strong thin Kevlar thread, go to http://www.scientificsonline.com and type in Kevlar into their search window. I would guess they ship to the UK...

Andy

Having flown many electric RC planes over the last 10 years (before I saw the light 3 years ago and became a CL retread dedicated to stunt) I found that I could usually transform an electric plane that flew like an anemic dog into a snarling beast. This was done by only exchanging the normal 6 cell motor battery pack for either a 7 or 8 cell battery pack. The weight increased slightly but there was a significant increase in power. Might be worth a try.
DennisV

Tim,
As someone said, "If I was going there, I wouldn't start from here."
Andy,
Thanks, I'll check it out. There sre two problems with my existing lines, drag and stetching. You might have the answer to both.
Dennis,
A 12 volt auto battery would give even more power! the set-up I'm using will give a short motor life on 7 cells. At this end of the scale, the weight of one cell (1/2 ounce = 8% increase, exactly the same as the increase in voltage) is more of a handicap than the slight increase in power from the extra voltage.
At my age, it's the process of flying round and round that I need to practice, not the pattern. I can now walk down to my local park and fly control-line anytime I like. If I can make it fly the F2B schedule, rest assured you'll all be the first to know.

hey she looks good i fly a chief in ots as to your line problem i would suggest you go to a good tackle shop and get some fine braided wire leader of about 35-40 lb this will help a lotespecially where stretch is concerned helps on drag too any idea what i would need in a motor and batt packs for a full size chief??
thanx smitty

Smitty,
From what I've found, 35 - 40lb is about 0.015" to 0.018". I need something like 0.004". I've already tried 0.008" and its about the same as the thread for drag. I think I need maybe 3 - 5lb line.
I've considered a full-size B C Chief and I reckon an 8 cell 1700mAh pack driving a geared 540 size motor. I can get around 10.000 rpm on a 10 x 6 prop with that set-up. However, the battery alone weighs 17 ounces. The problem then becomes safety.

A 12 volt auto battery would give even more power! the set-up I'm using will give a short motor life on 7 cells. At this end of the scale, the weight of one cell (1/2 ounce = 8% increase, exactly the same as the increase in voltage) is more of a handicap than the slight increase in power from the extra voltage.

Dave,

I am assuming you meant to say that a 7-cell pack will give you a shorter run time and this is of course correct.

However, aside from run-time concerns and your mathematical demonstration that the model would not be improved in going to 7- and 8-cell packs, my comment is that you won't know until you try. And I have seen a great many situations where uninspiring models were made to come alive by the very suggestion you have rejected out of hand.

The numbers might not crunch quite right, but the results are undeniable.

>the
>set-up I'm using will give a short motor life on 7 cells. At
>this end of the scale, the weight of one cell (1/2 ounce =
>8% increase, exactly the same as the increase in voltage) is
>more of a handicap than the slight increase in power from
>the extra voltage.
Arithmetic gone a little awry I'm afraid. 6 cells to 7 cells is a 16% increase in voltage which translates into well over 30% increase in power, since power is proportional to V SQUARED. All that for an increase of 8% in weight is the sort of trade-off that many of us flying electrics find very worthwhile. You might even try a slightly smaller prop to reduce current and still have more power than now.

I agree that the smaller GWS motors are not too happy on 8 cells but in my experience they are fine on 7 cells.

I'm terribly sorry for confusing you both. I really should have cut the crap and said that I'd tried it and it didn't work. Maybe you'd like to start another thread so you can continue the argument.
My indoor R/C aerobatic models work best on 6 cells, anything else is into diminishing returns.
My contribution to this thread is now closed.

Great looking project Iroquois!

If you are looking for some more punch, you might want to consider the GWS IPSD (dual motor drive) with the 4.8v wind, 'A' gearing and the same prop. You could then drive it off either 6 nicad/nimh cells, or a 2 cell lipo pack of 1200mah or more. The IPSD should be a drop-in on your mount (or very close to it) and will have a lot more punch.

Wondering- what are you using to control the motor. Do you have an on-off switch, etc?

A lot of out yaw there. Deliberate?

LAST EDITED ON Feb-23-04 AT 06:38 PM (CDT)
 
I'm terribly sorry for confusing you both. I really should have cut the crap and said that I'd tried it and it didn't work. Maybe you'd like to start another thread so you can continue the argument.
My indoor R/C aerobatic models work best on 6 cells, anything else is into diminishing returns.
My contribution to this thread is now closed.

Dave Day

Dave,

My, my. A little touchy today, aren't we?

While Dave seems to have left the building in a minor snit, I looked back and didn't see an argument. Instead, there were a couple worthwhile suggestions which I am a bit surprised are claimed to not have worked out well.

Too bad he ran out on us, I'm mildly interested in why the CL model did not respond to significantly more power, the tradeoff being slightly higher weight.

Alas...

Personally I regret upsetting Dave. I was confused enough to imagine this was a discussion forum. Obviously not, so in future I shall be careful not to reply to Dave's "not-for discussion" posts, unless I wish to say something like "That's brilliant".

I imagine that my indoor R/C models fly much better on 7 cells once I've sorted out the correct prop for them but I guess I must be wrong.