Thread Tools
This thread is privately moderated by Gadgetman, who may elect to delete unwanted replies.
Mar 15, 2008, 09:32 PM
Registered User
Gadgetman's Avatar
Thread OP
Discussion

Hyperion Super Chipmunk 70e Electric


HYPERION SUPER CHIPMUNK 70e ARF (Feb 2008)

This was my first attempt at a large electric model and I thought I’d pass on what I’ve learnt for the benefit of others. I found that by using ‘genuine Chinese’ components; it didn’t cost anywhere near what I expected. I hope this information will help you to ‘electrifly’ larger models. The Chippie has a wingspan of 1628mm (64”), the wing area is 691 square inches, the bare airframe weighs 1.5kg and the weight ready to fly is 2.9kg.

The Chippie has plenty of power and leaps in to the air in no time and goes vertical. Because of the low wing loading and wing design, it’s a very docile aircraft and I spend a lot of time just floating about with the power off. Stalls are mushy, with no tendency to tip stall. Landings with no wind take the length of the field as it’s floaty and a tail dragger. Any attempt to land before the speed bleeds off and it bounces back in to the air and tries to fly again.

The airframe is available from Hyperion dealers. I strengthened the fuselage opening with 3 X 1 carbon fibre. I made up a plywood box, which I dowelled to the firewall and mounted the motor to it with the supplied hardware. Baffles in each side of the cowl and holes in the side of the box send cooling air over the battery. I cut out a section of covering film on the underside of the fuselage to allow the air to exit. The motor is cooled by the centre hole at the front of the cowl and the air then passes over the speed control mounted on the under side. The battery is barely warm on landing, the motor and speed control are cool. I found (when the canopy blew off) that the magnets which secure the canopy aren’t strong enough and I replaced them with 2 spring loaded locking pins (Graupner part 1066) which cost $5 each.

The motor is a Tower Pro 3520-7T from unitedhobbies.com.
The diameter is 45.5mm and length is 51mm. Weight is 262gm (295gm with mount, screws and prop adapter). Kv is 600 RPM/volt. The maximum current capability is 56Amps and the maximum power is 850 Watts. Prop is an APC 13 X 8. If you type ‘Tower Pro 3520-07T’ in to your search engine, you should get a very detailed review of this motor from the Ampeer Newsletter.

The battery is a FlightPower 5S 3700 EVO25 (92Amps continuous/185Amps burst). I get 12 minute flights from a battery, which discharges the pack down to 10% capacity. I charge with Imax B5 balancing chargers from unitedhobbies.com. This unit charges through the balance socket on the battery and ensures that all cells in the pack are equally charged.

The speed control is a Tower Pro Mag 8, TP-70A from himodel.com. Speed controls are often difficult to set up, but the beeps on the Mag 8 are of different pitch, which makes it easy. It doesn’t have a BEC (Battery Eliminator Circuit) to power the receiver and I used a 3 amp ‘eWatts’ UBEC from wattsuprc.com.au. It’s listed under ‘Brushless ESC’ as EW-UBEC. I’ve had no interference issues with the BEC and the main battery can’t go below 16.5V because of the Cellshield; so there’s always power for the receiver and servos. Being lazy; I like not having to charge and worry about a separate receiver pack.

In flight, a Cellshield from robotshop.ca protects each cell in the battery pack from over discharge. The Cellshield plugs between the throttle socket
on the receiver and the speed control. The Cellshield board plugs directly in to the balance socket on the battery pack (polarity doesn’t matter) and if any cell drops below a preset voltage (I’ve set 3.4 volts), power is reduced and it’s time to land.

Flying the Chippie for 8 minutes of sport aerobatic manoeuvres with an Eagletree data logger (from wattsuprc.com.au or unitedhobbies.com) gave the following information. Highest power was 1.067 KW. The highest current draw was 58A. Average is 13.6A. I exceeded 52A draw 18 times. The usual peak current draw is around 40A. The minimum cell voltage dropped to 3.5V (is good). Over the 8 minutes, 2.27A/hr was consumed from the battery. The charger returned 2.29A/hr to the pack.

Large electric models have the potential to cause serious injury. Unlike internal combustion engines, electric motors don’t make any noise when they’re ready to go. A runaway model with over a horsepower at the prop could do serious damage! I mounted a female Deans socket flush on the side of the fuselage and it’s wired in the positive lead to the motor. The motor lead is therefore open circuit; until a shorting plug is inserted. When not in use, the shorting plug is stowed in a female socket mounted in the fuselage.

In the pits I hold the shorting plug, switch on the transmitter, connect the battery and Cellshield, and secure the canopy. The electronics are now working but the motor can’t operate. I carry the model to the field, check the throttle is off, plug in the shorting plug (which arms the motor) and do the pre-flight checks. After landing I walk over to the model, pull the plug and carry the Chippie back to the pits. Safe.

The plane looked strange floating past with no pilot so I bought a pilot figure. I painted his blue hat red to match the airframe and put him on a weight loss program with my Dremel! There was a lot of useless, heavy bog inside. The pilot figure is secured with 2 small self tapping screws.
Sign up now
to remove ads between posts
Mar 18, 2008, 05:03 AM
Mansell Models
N827TM's Avatar
Gadgetman,

Thanks, for posting your setup and flight charecterics. I just ordered mine and am looking forward to have it flying soon. I plan on flying mine using a 6S setup.

Tom
Mar 24, 2008, 04:46 PM
Registered User
Gadgetman - can you list specific component weights please? 1.5 to 2.9 Kg seems quite a jump and relatively heavy fro 64" wingspan, although I notice you find it flies without too many vices.

If you happen across the Hyperion Yak54 40e main thread, yuo'll see I have a thing about building light!
thanks
Nigel
Sep 21, 2008, 06:31 PM
Registered User
Well, since no reply came on the weight issue, lets take a look at this...
We are trying to account for roughly 49 ozs, between basic airframe and total flying weight.

How about..motor 12 ozs, esc & bec 3 ozs, 4 servos 6 ozs, Rx 2oz, 6S pack 20ozs, prop and adapter 3 ozs ....that's 46 ozs right there.

Amazing how it adds up ...!

Bill
Sep 23, 2008, 04:50 PM
Registered User
Hmmm, good point! Thanks for that Bill, and taking a fresh look, if I'd bothered to read the post, I could have worked that out by checking the components he'd listed... d'oh.

Appreciated.
Nigel


Quick Reply
Message:
Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Hyperion Super Chipmunk .70e Warbirds Rule Sport Planes 233 Sep 23, 2013 02:49 PM
Discussion Hyperion Super Chipmunk 10e Raycer Parkflyers 152 Aug 12, 2013 04:29 PM
Discussion Hyperion Chipmunk 70e Any one with info?? kov Australia 79 Aug 25, 2009 04:37 PM
Electric Power for Super Chipmunk FV Racer Sport Planes 8 May 11, 2008 07:29 PM
Sold Hyperion Super Chipmunk 10e RTF - PRICE REDUCED Keitha Aircraft - Electric - Airplanes (FS/W) 3 Sep 07, 2007 06:49 PM