Edge540Aerobat

Hi All!

I'm thinking about making the Astro Hog I'm building electric power. I'd like to decide soon as I'm getting ready to layout and build the firewall. I bought the kit new from Sig about 6 years ago, just now getting back into the hobby, and exploring the world of EP.

What do you all think I may need for a "strong performing" 'Hog? (want something fun to fly within the capabilites of the Astro Hog...not just for puttin' around the sky) (prop, motor, li-po battery, and esc)? Let's hear your combination ideas.

The instructions of this kit claims that the final weight will be between 7 to 7-1/2 lbs (w/ a typical .60 sized engine). However, in reading other posts here, they say that they actually come out a little heavier (8lb or even a little heavier).

This is my first real venture into electrics and don't know a whole lot yet. If I stick to glow power, I'd like to try the OS AX series engines...probably the 55AX or the 65AX. The 65AX is only 17.5 oz w/ the std. muffler and they say it makes 2.0hp at 16,000rpm! But...I'd like to use the quiet and clean power of electric for this one!

-Dan

TedMo

From what I read in your post I would say you're underpowering your Hog. I would go with a 91 4 stroke and you will have a great plane. The Hog was my first aircraft with reeds way back then.

tIANci

Dan if you want good power and not putter around then I would say use the following as a baseline to work from:

Battery - 25C 6S 3,300 to 4,900 ... look at HobbyCity/HobbyKing stuff.

Motor - the likes of AXI 4130/16, Hacker A50-16S, Rimfire 5055-500 ... I would stay clear of the HobbyKing motor, they got dodgy magnets so if you want to push it hard you may potentially end up with a lemon.

ESC - Turnigy PLUSH 80A, they work great. No need external power/UBEC for the RX, just plug and go

Prop - 14x10 to 16x10, depending on the motor KV.

The above should be nice for a 7-7.5 lbs plane. It will 3D a 6.25 lbs plane with good authority. Please purchase a WATTMETER so you know how many amps etc the system is pulling. It the best investment for going EP. You can test the various props and get know how many amps is being drawn.

Build a nice hatch for the battery access with a good long battery tray, remember the electric motor is much lighter than a glow engine, so you will want batteries placed around the tank area. Attached is a picture as to how I mounted my motor to the firewall. If you make your own standoffs, remember to have some thick washers at the base ... if not it will not be stable. The base of the rods will dig into the firewall and it gets unstable.

Don't forget about inlets and outlets for airflow. Think of a place for the ESC and ensure its got good airflow around it.

Have a great build!

tIANci

...

Edge540Aerobat

2 Stroke...4 Stroke... or Electric Power? Choices, choices.

E-Flight has an interesting article on their motors. With this info. I can get in the ballpark.

[link]http://www.e-fliterc.com/Articles/Article.aspx?ArticleID=1563[/link]

Just for a quick comparison:
The OS 91 FS:
FS-91S II 1.60hp @ 11,000 Stunt: 11x10, 11x11, 12x9.5, 12x10, 12x11
weight: 22.9oz.

The OS 65 AX:
Displacement: 0.65 cu in
Practical RPM Range: 2,500-16,000
Output: 2.0 hp @ 16,000 rpm
Weight: 17.5 oz w/ std. muffler

First off...let me ask would you guys like the 4 stroke over the cheaper, lighter 2 stroke for the 'Hog? I never had a 4 stroke on any plane as I was always steered away from the higher prices.

Now if you take a look at that Article from E-flight...
The article (for their motors) gives a range of 90–110 watts per pound: Sport aerobatic and fast flying scale models. I'm going to assume that my Hog will probably be about 8lbs.
So 110watts x 8 = is only 880watts per thier recommendation.

1 horsepower = 746 watts
2hp (the OS 65AX - peak) = 1492watts.


What do you guys think?

Edge540Aerobat

Here's a link to RimFire motors...

http://www.electrifly.com/motors/gpmg4505.html

in looking at the specs of all the motors, I have question...what's the definition between burst watts and continuous watts?

I wonder how the Rim Fire .55 would work?

tIANci

Dan ... BURST means a short period only. A few secs. Continuous means it can manage that amount of watts/amps for the duration of the flight so to say. If you ask me take the RimFire 80 ... you can go 6S with that motor. I am running one on 5S and a 16x10 and 17x10 prop, that would prop be too big for the Hog. Go with 6S and something in the 15x8 range.

Edge540Aerobat

Thanks tIANci!

Yeah sounds like the RimFire 80 would be a great way to go.

Think I'm going to give it a try!

-Dan

CanDo

Keep in mind too that with the Hog's trike gear, a 14" or bigger prop will give you ground clearance "challenges". My old Hog with a OS .91 4 stroke and a APC 13x8 prop could just hover at full throttle and it weighed 8 lb. Because I suspect the HP ratings on IC motors is a little over rated, I'm betting an 8 lb electric Hog with 900 watts of motivation will be a real kick to fly! Good luck!

Broken Wings

My Feedback: (20)

Just some food for thought, I was curious as to the weight of my Astro Hog so I pulled it off the wall and weighed it....It's right at 7 1/2lbs with an OS FX.61 engine.

I've got a pretty large A123 battery installed as well as some extras...

Edge540Aerobat

Hi fellas...

I've actually gone a less expensive route and stayed w/ glow power. I'm installing a Super Tiger G90 (2 stroke) in it right now. I'm curious to see what it does once I get her completed.

Once I figure out how to post pics on here, I'll do a little show and tell.