SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Oct 14, 2014, 11:05 PM
Up-Out-&-Gone
demondriver's Avatar
United States, SC, Charleston
Joined Mar 2007
15,943 Posts
Quote:
Originally Posted by ruff1 View Post
For your battery gurus... I need feedback!

I see that HobbyKing has the MultiStar line of lipos:
http://hobbyking.com/hobbyking/store...MultiStar.html
Their claim to fame is larger capacity at the expense of discharge rate. In my case, if I have the math right, I'm OK at a 10C rate with a 4000 mah pack (40 amps) - this bird will not draw more than 35 amps total (approx. 17 amps max per motor).
It has been difficult finding a 3S pack in a capacity of greater than 3500 mah. This pack might be the answer to my needs, even though it is designed for multi-rotors. I can always put in two regular packs in parallel, but that may add up to 150 grams, and that may not be good.

I will wait until I get to the very end of the build to sort out the battery selection once I see how much weight "wiggle room" I have. She won't be as hungry as the EDF beasts that DD and others build.
Kevin my good man, just my opinion Sir but very Low "C" count Lipos are for Radios or RX inside planes, you want as high a C count as possible and the "Higher" your mah Rating the Higher your weight.

Have a look at these Batteries.

http://hobbyking.com/hobbyking/store...dProduct=45132

http://hobbyking.com/hobbyking/store...dProduct=45130

http://www.hobbypartz.com/98p-60c-2200-3s1p-3333.html

These lipos are 3S, They have a High "C" count, are pretty light, and they have a good medium Mah of 2200-to-2600! Plus they are reasonably priced.

if you go with anything larger than 3500 mah Lipo it will make your 404 WAY to heavy!

But every Modeler has a different opinion.
demondriver is offline Find More Posts by demondriver
RCG Plus Member
Sign up now
to remove ads between posts
Old Oct 14, 2014, 11:55 PM
Up-Out-&-Gone
demondriver's Avatar
United States, SC, Charleston
Joined Mar 2007
15,943 Posts
Quote:
Originally Posted by ruff1 View Post
OK, after doing a bit of filling in on the wing box, I have it close enough to finish up the fit once I get the wing top panel installed and fuselage skinned. Taped on some fff to the fuselage to see just how far off I am; not too bad.

I'm ready to glue the top wing panels on the center section, but need to sort out my weights so I have something good to hold down the panel. I may be able to get a bag of lead shot that is fairly heavy, and that would give me some good hold-down with flexibility.
That's all you need kev, just start sanding that foam into the curved wing fairing.
demondriver is offline Find More Posts by demondriver
RCG Plus Member
Old Oct 15, 2014, 06:33 AM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
North AL, USA
Joined Nov 2009
1,934 Posts
Thanks for the info DD. When I weighed the 4-0-4 earlier I did it with two 2200 mah batteries to get an approximation of a larger battery. I didn't weigh them though, but everything minus paint she is at 3.8 pounds, right where I expected her to be. Still, the larger C rating batteries might make sense. The battery will be the last major decision and purchase on this build.
ruff1 is online now Find More Posts by ruff1
Reply With Quote
Old Oct 15, 2014, 06:45 AM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
North AL, USA
Joined Nov 2009
1,934 Posts
Separate UBEC for Retracts?

I was surfing through the threads and there was one about the need for a separate UBEC for retracts in addition to the one for the receiver. Their claim was power draw and the receiver stalling.
I measured the retract power draw and it spiked at 3 amps for about 2 seconds but settled in at about 1.5 during the cycle. The UBEC is rated up to 5 amps, is th a too close? I have 9 servos in this bird, of which up to five may be working at one time, Not likely to happen during a gear operation but could put in a bit of elevator as CG will shift backward and forward during cycle.
I'll just have to test the CG shift once she is almost done to see how far it is moving. With the design I hope she won't be too picky about that and will work in a wider range.

The UBEC isn't expensive weight and cost wise, plus plenty of room to fit another.
ruff1 is online now Find More Posts by ruff1
Reply With Quote
Old Oct 15, 2014, 06:48 AM
Up-Out-&-Gone
demondriver's Avatar
United States, SC, Charleston
Joined Mar 2007
15,943 Posts
Quote:
Originally Posted by ruff1 View Post
Thanks for the info DD. When I weighed the 4-0-4 earlier I did it with two 2200 mah batteries to get an approximation of a larger battery. I didn't weigh them though, but everything minus paint she is at 3.8 pounds, right where I expected her to be. Still, the larger C rating batteries might make sense. The battery will be the last major decision and purchase on this build.
Kevin. . . I totally understand your feelings about buying the wrong equipment for your 404 and wasting allot of money and having to do it all over again.

Another idea is to copy the power plant of a similar sized twin Arf like the Dynam DC-3 or the large Park zone mosquito or the new ME-110 . . . Find a similar twin electric plane that is about the same size and weight as your 404 and simply "mimic" it's motors, Esc and battery setup.. . . And even the prop size.

Might save you a TON of migraines.
demondriver is offline Find More Posts by demondriver
RCG Plus Member
Old Oct 15, 2014, 06:59 AM
Up-Out-&-Gone
demondriver's Avatar
United States, SC, Charleston
Joined Mar 2007
15,943 Posts
Quote:
Originally Posted by ruff1 View Post
I was surfing through the threads and there was one about the need for a separate UBEC for retracts in addition to the one for the receiver. Their claim was power draw and the receiver stalling.
I measured the retract power draw and it spiked at 3 amps for about 2 seconds but settled in at about 1.5 during the cycle. The UBEC is rated up to 5 amps, is th a too close? I have 9 servos in this bird, of which up to five may be working at one time, Not likely to happen during a gear operation but could put in a bit of elevator as CG will shift backward and forward during cycle.
I'll just have to test the CG shift once she is almost done to see how far it is moving. With the design I hope she won't be too picky about that and will work in a wider range.

The UBEC isn't expensive weight and cost wise, plus plenty of room to fit another.
Kevin the power draw from your servoless retracts is minimal during a flight. . . If you plan on dropping then retracting your gears 50 times during a flight then a separate UBEC would come in handy but if you cycle your retracts once or twice during a flight then a separate retract UBEC is a waste of money, now a low voltage alarm for your 404 might be helpful.

Now if you wanna use a BEC as a backup power source for your Receiver if your main lipo packs fail and you need power to steer during a dead stick glide then a BEC supplying backup power makes sense.
demondriver is offline Find More Posts by demondriver
RCG Plus Member
Old Oct 15, 2014, 07:13 PM
Up-Out-&-Gone
demondriver's Avatar
United States, SC, Charleston
Joined Mar 2007
15,943 Posts
Kevin Have a Look at this RC Arf B-25, Would its dimensions weight etc be kinda close to that of your 404?

if so then either buy it and put its parts in your 404. . . or simply copy its parts.

http://www.hobbyking.com/hobbyking/s...50mm_PNF_.html
demondriver is offline Find More Posts by demondriver
RCG Plus Member
Old Oct 15, 2014, 09:06 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
North AL, USA
Joined Nov 2009
1,934 Posts
Good info, thanks. I think I can make the current setup I have work OK, I should be around 60-65 watts per pound and with the airfoil I have there should be plenty of lift. I don't have a problem bumping up the motors and ESCs if I need to.
The B-25 is a bit smaller than the 4-0-4, the kv rating is higher and it weighs about a pound less.
ruff1 is online now Find More Posts by ruff1
Reply With Quote
Old Oct 17, 2014, 07:15 AM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
North AL, USA
Joined Nov 2009
1,934 Posts
Top Panel Glued On

OK, I managed to glue on the first of the two top center wing panels. I think it came out really good. Very strong with it being FFF.
I'll need to sort out how to finish up the leading edge; balsa would be great, but if she ends up having a hard-shell covering that won't be so important.
ruff1 is online now Find More Posts by ruff1
Reply With Quote
Old Oct 17, 2014, 03:56 PM
Up-Out-&-Gone
demondriver's Avatar
United States, SC, Charleston
Joined Mar 2007
15,943 Posts
Quote:
Originally Posted by ruff1 View Post
OK, I managed to glue on the first of the two top center wing panels. I think it came out really good. Very strong with it being FFF.
I'll need to sort out how to finish up the leading edge; balsa would be great, but if she ends up having a hard-shell covering that won't be so important.
Kevin, Love the progress on your 404's wings! using Fan-Fold will keep her nice & light.
demondriver is offline Find More Posts by demondriver
RCG Plus Member
Old Oct 17, 2014, 04:32 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
North AL, USA
Joined Nov 2009
1,934 Posts
Proportionally not as light as your lite builds! :-)
ruff1 is online now Find More Posts by ruff1
Reply With Quote
Old Oct 17, 2014, 04:38 PM
Up-Out-&-Gone
demondriver's Avatar
United States, SC, Charleston
Joined Mar 2007
15,943 Posts
Quote:
Originally Posted by ruff1 View Post
Proportionally not as light as your lite builds! :-)
Don't be to sure Sir, your building a light bird No-Doubt!
demondriver is offline Find More Posts by demondriver
RCG Plus Member
Old Oct 17, 2014, 04:53 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
North AL, USA
Joined Nov 2009
1,934 Posts
When I see the builds of Ethan and Redtail the 404 is a heavy! I will definitely embrace lighter building techniques on the next one.
ruff1 is online now Find More Posts by ruff1
Reply With Quote
Old Oct 17, 2014, 06:12 PM
Up-Out-&-Gone
demondriver's Avatar
United States, SC, Charleston
Joined Mar 2007
15,943 Posts
Quote:
Originally Posted by ruff1 View Post
When I see the builds of Ethan and Redtail the 404 is a heavy! I will definitely embrace lighter building techniques on the next one.
Very true!
demondriver is offline Find More Posts by demondriver
RCG Plus Member
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Idea I'm Considering a Martin 4-0-4... ruff1 RC Airliners (Commercial, Cargo, Troop Carrier) 62 Dec 20, 2012 09:56 PM
Sold Sig 1/4 scale Spacewalker,Pica 1/6 scale Spitfire joedoan Aircraft - Fuel - Airplanes (FS/W) 2 Jun 02, 2012 11:45 PM
Sold 1/4 scale 4 1/4" inflatable cub tires lla Aircraft - General - Miscellaneous (FS/W) 0 May 28, 2012 10:55 AM
Build Log L-19 1/4 Scale Vailly Aviation Build Greggo Scale Fuel Planes 5 Dec 02, 2011 08:55 AM
Sold 1/4-Scale Fairchild PT-19 DanSavage Aircraft - Fuel - Airplanes (FS/W) 1 Aug 13, 2007 01:40 PM