rahtware

Hi all

A couple of years ago I scratch built a 199g (7oz.) 1/8-scale copy of a southern California ultralight. The original plans for a 1/4-scale model of the “Desert Duster” were published in the now defunct Model Builder magazine. This is my third model of this plane. The first was a .15 (nitro) powered 1/4 scale, the 2nd was a rubber powered peanut scale, and now the 1/8 scale E-powered.

The E-powered version gave mixed results due to the NiMh battery. I used a 7 cell 300mah NiMh to power the GWS motor. On a hot day the plane flew great giving almost 15 min flights at 3/4 power. But, on a cold day (even with the battery fresh off the charger) the plane might not get off the ground. So I hung it in the rafters of the garage.

Well, today I made the switch to LiPo power. I picked up an 860mah, 2 cell Thunder Power battery and a Castle Creations Pixie-7p ESC. The weights aren’t that much different, I saved 1g on the Pixie over the GFS 12 that it replaced. The 300mah/8.4V NiMh battery weighed 55g, where as the 860mah/7.4 LiPo weighs 47g for a savings of 8g and a potential tripling of it’s flight time.

I hope to fly it Friday morning, will post how it does.

rahtware

Here are some pics of the original installation. The NiMh is hiding under the JR RX.

rahtware

Here are comparison pics of the components that I exchanged. The Pixie is the small ESC.

rahtware

And here are a couple of pics of the(almost) completed reinstallation. The LiPo is just a tad wider (but still fits in the tray) and much shorter than the NiMh.

I can’t wait to see how it does!!!

Woody 51

Don;t forget to make sure that you have a charger that can handle Lipo's Larry. One that can do NiMH and NiCAD only, won't be suitable.

rahtware

Woody 51

Thanks for the input. I have a Triton that has a LiPo function... But even with that I was a bit nervous during the first cycle due to all of the warning notices (5) that came with the Battery.

rahtware

Thought I should show a couple of pics of the DD in flight.

Woody 51

I know what you mean. I have an APACHE Charger to go with my collection of POLYQUEST Lipo's. Then I realised that I really needed one that could do all types of cells and packs as I was also starting to build a collection of other brands, without the seperate charge jack that is peculiar to POLYQUESTS.

So I purchased a PLATINUM EX unit. It does the lot, from Lipo's to Wet Cell Auto Batteries.

When I finally figure it all out, the whistles, bells and buzzers I mean, I should also be able to become a Philadelphia Lawyer!!!

rahtware

So true...

"So... did it fly?" You ask. YES IT DID!!! Man do I love LiPos and am kicking myself for not making the conversion sooner.

The notes:

Charged the battery a day before flying, took it out on a cold morning (both I couldn't do with the NiMhs), pointed it down the road and advanced the throttle.

Before I get into the results I feel I should list some specifications... Plane's weight is now less than 6 3/4 oz. (191g). True wing area (not counting the cabin top) is 6.5" X 30" or 1.35 sq ft. This works out to just over 5 oz per sq ft wing loading. This number drops even farther when I include the giant flying-stab. Power is a GWS IPS DX2 with an 8.43 prop.

As I advanced the throttle I applied a touch of rudder and elevator and she lifted off into a gentle climb out. In the air I had to keep bumping in positive elevator so I tried to set the trim but it kept wanting to nose down... Oh, new battery, new CG! I dropped the power and brought her in for an acceptable landing considering I haven't flown in over a year.

Plan to move the battery and try again after a Drs. appointment I have this AM.

Let me say it again... Man do I love LiPos!!!