1/4 Scale Cub followed me home from the Model Plane Auction yesterday - RC Groups
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Nov 06, 2017, 10:01 PM
Flying again - 4th time
FOGeologist's Avatar
Discussion

1/4 Scale Cub followed me home from the Model Plane Auction yesterday


Went to the annual model plane auction at Wings Over the Rockies Aviation Museum yesterday. This 106", 9.2 lb 1/4 Scale Cub followed me home as I appeared to be the high bidder at $150. OAL is about 57".

I'm gong electric in it. I have had some good luck with Hobby King gear, and I think I'll try a heavier-duty Turnigy motor and some metal gear servos.

1. I'm ready to listen to your suggestions on ESC and cell count. I live @ 5500 feet above MSL and may need a little bit of extra prop. I won't stunt wildly.

2. This is my first giant scale bird. I'm an intermediate pilot. I like warbirds.

3. I might try to find some decals for this monster or make them myself; I would not hesitate to paint the odd fabric coating.

4. I don't know what brand this bird is or how old. Claim was it's never been in the air. Looks like it was not built by a hobbyist as it is really professionally assembled.
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Nov 07, 2017, 12:31 AM
Registered Airplane Offender
greenseaships's Avatar
A hundred and fifty DOLLARS?!?!

It could only be because no one had a car big enough for it! Wow. I'm gonna start showing up when my local club has their auctions!

Seriously fantastic grab. If you need inspirational viewing material for the conversion work, enjoy this!

1946 Piper J3 Cub "Barn Cub" (7 min 1 sec)
Nov 07, 2017, 09:23 AM
Registered User
I have an old 1/4 scale H9 PA-18 supercub and it flies fine w/ a G26cc. At 1.7kg it has some tail weight in it to balance. I also have a used 1/4 scale H9 J3 that came w/ a G20 but I'm repowering it w/ a Saito FG30 (actually a GA180 converted to gas.) Those are around 1.1-1.2kg so I shouldn't need tail weight. So that is the ballpark weight I'd shoot for w/ the motor.

I have quite a few big electric planes. I'm a fan of overpowering them too. Can swing a big scale prop at reasonable speeds esp w/ low Kv motors. Just keep your left thumb from pegging the stick constantly I'm also a fan of higher voltage to get the current lower. 12S @ 50A is the exact same power as 6S @ 100A. Anything over 6S typ takes a HV rated ESC. But most motors in the 20-30cc range typ have low Kv and you'd have a hard time swinging a prop fast enough w/ those on 6S anyway. But the motor sizes you'll be looking for are sort of on the edge and can probably run w/ either. I'm sure a Turnigy G160 or Rotomax 1.60 would fly a cub fine.

I can also recommend ecalc.ch. Its not perfect but has lots of the turnigy motors on the list and will give you an idea of the expected power draw. Monthly (or annual) subscription is cheap and can save you lots of $ on buying the wrong stuff. I use it for most all of my planes.
Nov 07, 2017, 02:22 PM
Flying again - 4th time
FOGeologist's Avatar
Thanks for the replies! I'll post here with my analysis, purchases and installation.

Side note: there's no scale ANYTHING on the inside of the plane. I could probably spend a king's ransom kitting it out with cool scale details.

I won't do this initially, as my first goal is to get it airborne.
Last edited by FOGeologist; Nov 07, 2017 at 02:35 PM.
Nov 08, 2017, 06:10 PM
deltas are cool
AIR SALLY's Avatar
the turngy G-160 is a good motor on 8s with a 100amp esc, they make different kv's so yu need to find out what prop you want to run . the 290 kv spins a 22X13 really good flies a 14 lbs Bearcat . you might want less pitch for a cubby .
Nov 09, 2017, 12:28 AM
Flying again - 4th time
FOGeologist's Avatar
I've bought a year's scrip to ecalc - it's a great tool to rough out your build.

I have seen some good Turnigy components which will produce tons of extra thrust, give me the flight time I need, etc. I will get more serious about a selection this weekend.
Nov 11, 2017, 12:37 AM
Flying again - 4th time
FOGeologist's Avatar
First component bought: A Turnigy dlux 80-amp speed controller from HK.

Half price, got it for $43! It's got 2-8s capability and can log data. I have telemetry in the DX7s and can get a Lemon with telemetry, stab (wouldn't need it for such a big bird) and satellite for like $40.

Weight nominal @113 g. Slick airframe weighs in at 4335 g. I figure three big servos at 60 g each (180 g) plus Turnigy Aerodrive 5065-320 kV at 531 g, and an additional 40 or so for the receiver and satellite, plus maybe a Zippy Compact 7s 5800 mAh cell at 931 g and an Aerostar Electric Series wooden prop at 64 grams, plus a motor mount at 89 g and all-up weight should be around 6300 grams.
Last edited by FOGeologist; Nov 11, 2017 at 01:15 AM.
Nov 11, 2017, 03:53 PM
Registered User
Looks good. FWIW, I prefer even numbers like 8s because its easy to get two 4s to put in series plus use them for other things. Chargers over 6s are much rarer and more costly too. I seem to have lots of planes that run on 4 or 6 cells so most of my big stuff has gravitated towards 2x those.

I don't have tons of time on them yet but my big P3 Revolution bipe came w/ JX PDI-6221MG servos. They are rediculously cheap so Im skeptical but them seem well built and are holding up even to 3D type moves on large surfaces. They have a little play in the metal gears new but thats really the only fault I can find.

You can actually share your ecalc setup (or store it in your notes to come back to rapidly.) There is a small button on the left called 'share' below the calcs and that will create a unique URL w/ all your info. Took me a long time to find that.

Edit:
for example
Last edited by smdub; Nov 11, 2017 at 04:05 PM.
Nov 12, 2017, 12:17 AM
Flying again - 4th time
FOGeologist's Avatar

How do you get ecalc to recall your configuration?


I can't find a "load" button anywhere on this thing. I hope I don't have to re-enter the data every time - I did save the file, but nothing's coming up.
Nov 12, 2017, 07:50 AM
Registered User
Enter the data
click 'calculate'
click 'share'
copy and paste the URL to save

to reload: copy the saved URL into a browser window.
you have to be logged in for the load to work. So you might have to login and then hit refresh on your browser if it didn't save a cookie.

I keep a google doc w/ notes on all my planes. In there I save hotlinks to ecalc data.
Nov 24, 2017, 12:29 AM
Flying again - 4th time
FOGeologist's Avatar
Update: After a bit of consideration, I do think 2 x 5000 - 5500 4s is the way to go, if placed in series to give 8s. Flight times report 8-9~ish minutes, but I notice that every time I fly my other birds, when I return my batteries for charging I am using perhaps 50% to 60% of the charge. I am admittedly a sober pilot, spending little time with the throttle in the "red zone." I believe I might eventually be able to fly 12-15 minutes on the two batteries.

Next component:

Great Planes Brushless Motor Mount Medium Motors: 81 grams. Purchased from Tower Hobbies; should make the Turnigy Aerodrive 5065-320 kV motor stick out of the nose of the Cub juuuust right. Weight 81 grams.

Also: Purchased an Aerostar Electric Series Wood Propeller 18x8 from HK. Should be here any day. Will weigh and balance when it gets in.

Planned: Battery purchase - Zippy Compact 6200 mAh 4s battery 589 g, x 2 @ $48.02 each. Will need to adapt the connectors to XT90 standard and reconfigure a charging lead to mate to the leads. Also, will have to buy or make an in-series connector to link these two batteries together.
Nov 24, 2017, 06:06 AM
Just Plane Crazy
datazman's Avatar

Good choice of battery


FOGeologist:

I have been following this thread with a passing interest until now.

I have been using Zippy Compacts (5800 mAh) in 2 of my 12S model aircraft for a few years now. They are incredible performers. Not once have they puffed on me. Output is almost a solid flat line as flight time increases. I may be old school but only charge at 1C and that seems to work well for this battery formula. I feel if you continue to only discharge your packs 50 - 60% your new ones should last you several seasons.

I am looking forward to following the finish of your project.

Ta Ta for now.
Paul
Dec 13, 2017, 07:27 PM
Flying again - 4th time
FOGeologist's Avatar
So the bird is really coming together - I just placed the order for the "heart of the beast," the motor, a couple of days back. Should be in soon. All I lack is the two batteries and the receiver.

I will make my "Hobby King Wishlist" known to my relatives, for there is a "certain holiday" coming up for me, LOL.

So I will get some photography done when the motor gets here - more details about the plane, the assembly of the components, the next purchase and installation, and ultimately the first startup, taxi and flight.

Ought to be entertaining. Although I've been flying for years, I am not an experienced pilot when it comes to big/heavy stuff. I have a great flying area that is safe, tons of room for mistakes, and good reflexes. I have a solid support team, including a much more experienced pilot.

I'll bring the camera!
Dec 20, 2017, 09:33 PM
Flying again - 4th time
FOGeologist's Avatar
Update: I have mounted the servos (this took me a surprisingly long time!) and ordered the batteries and Lemon RX with stab and diversity.

The following posts document my efforts (with some whimsical license).
Last edited by FOGeologist; Dec 22, 2017 at 09:48 PM.
Dec 22, 2017, 09:47 PM
Flying again - 4th time
FOGeologist's Avatar

In with photos!


It's Saturday, December 16th, and I think, "Hmmm, you've got the servos, the speed control and the motor. You should mount this stuff up and see how it's working out. Ought to be quick n' easy..." Yes, I am an idiot, even though I've owned my particular brain for 53 years and know how it "works."

So I walk into the RC Den and... it's a DISASTER!

I immediately ran out screaming like a small child running from the Texas Chainsaw Massacre gang!!


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