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Old Oct 06, 2011, 11:40 AM
I ain't got it!!!
USA, SC, Spartanburg
Joined Apr 2001
867 Posts
Another fllight report

I flew the LT-40 again last night. It was another great night for flying. The wind was calm, the sun was going down, the sky was clear. I used the 13x6.5prop this time and flew most of the flight at about 60 to 75% throttle. I did 2 or 3 touch n goes. Everything else was steady at the 60 to 75% throttle setting. It flies nicely with this prop - very scale like. With the 13x8 it had a lot more torque and bite, but with the 13x6.5 it was very sedate. I got over 12 minutes of flying with this setup - better than I had hoped. When I reconfigured the plane from the OS 52 4 stroke to the E-motor, I was hoping for 8-10 minutes of flying time, so I'm thrilled with the results, and pleased that I did the conversion.


Adam
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Last edited by Flying Low; Oct 06, 2011 at 08:30 PM.
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Old Apr 04, 2012, 04:31 PM
Registered User
Joined Apr 2012
1 Posts
Quote:
Originally Posted by scirocco View Post
Sweet. I think you might also find good results staying with the 8S but going with a 13x10 instead of 13x7. You'll get a bit more thrust for when you need it, and the higher pitch speed at full throttle means that when you back off to cruise, the motor still turns enough rpms to give comfortable cruise speeds.

I found going from 12x8 with a predicted pitch speed of 62mph, which looks fairly high for a trainer, to 12x10 at 77mph just gave better all round performance, at only a small penalty on run-time.

Nice video, particularly the takeoff. You know, about the same as when I first flew my LT-25 on the same power/lb with an old Aveox geared inrunner about the same vintage as your Astro.

You've just proved to yourself that in an efficient setup with a big prop and a big wing, 50w/lb is heaps. It's a shame people are scared to try under 70-100W/lb because 'everyone' says that's what you need as bare minimum. I'm convinced for this style of aircraft, the old 50W/lb is tried and true, and even more so with an efficient system, whether brushed or brushless. Also, the higher voltages that we can readily use for now give even better efficiency, ie more thrust per watt.

Congrats on a great rescue from the trash of a sweet flyin' model!
Just for the fun of it, I went back and calculated the power/lb ratio for one of these old trainer aircraft as originally manufactured. The Aeronca 7-AC Champ had a 65HP engine (48470W) and a 1220 lb. gross weight. That's 39.7 watts/lb. As you say, 50w/lb is heaps!
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Old Apr 14, 2012, 08:53 AM
airplane crasher
jimjxsn's Avatar
Roxborough Park, Colorado
Joined Nov 2004
156 Posts
Hi Sam,
Very nice LT-40!

I was wondering, did it balance out without adding weight?

What spinner are you using and did it bolt right on?
Thanks,
Jim


Quote:
Originally Posted by Tracon View Post
Hi Guys,

I converted my LT 40 a few months ago and added a few addons...

I've set her up for both land & water flying, she has tons of power with no issues on floats.

My LT 40 setup is:

E-Flite Power 46
Castle Creations Pheonix 80 ESC
Dimension Engineering SportBEC Switch-mode BEC
Turnigy 5s 5000 LIPO
12X8 APC

Hope you like it...

Sam













Here's some pictures of her with the wheels on:















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Old Apr 15, 2012, 12:39 AM
Team Tracon !!!
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Canada, BC, Gibsons
Joined Jan 2003
2,748 Posts
Hi Jim,

Sorry to take so long to get back to you, been away for the day..

I went with the 5s 5000 and all that weight up front made her balance just a tiny bit nose heavy...(not out of the range though, so it was as close to balanced as it gets)

For me I like them that way and she flys awesome on wheels and on floats...

As for the spinner I ordered a 2.5" from hobby king, I think it was about $6-7.

Sam
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Old Apr 15, 2012, 06:55 PM
Right Rudder
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USA, FL, Orlando
Joined Nov 2010
9,272 Posts
Tracon,

That is perhaps the best looking Sig Kadet LT-40 around!

I wish my was that good looking!

I am jealous!

Happy Landings!
Carlos
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Old Apr 15, 2012, 11:15 PM
Team Tracon !!!
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Canada, BC, Gibsons
Joined Jan 2003
2,748 Posts
Hi Carlos,

Thanks again for the nice feedback..

I see you have one of those Parkzone MK IX Spits...

I got one a while ago and tried to get the maiden on today but it was too windy...

I did a few paint mods on mine to trick it up a bit...hope to have pictures soon...

All the best,
Sam
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