Sig LT25 - RC Groups
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Sep 18, 2002, 09:04 PM
Thats gona be expensive
Q-HUNTER's Avatar

Sig LT25

Looking to power a LT25.
New area to me I usually fly sailplanes...
I really, really like direct drive but if I absolutly must use a gearbox I will.
I like climbouts at 45 degrees or better.
I like thrust not speed. ( I know, I know, geared is better for this) Can run from 8 to 16 cells. Are the new AXI motors too small?
Also would like to keep out of the welding amp ranges (60-100).
Pretty damn pushy huh
thanks Ken
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Sep 18, 2002, 10:10 PM
Name it, I've crashed it
Bill Germanson's Avatar

LT-25 power options

Your a lucky man, IMO, to be having such a problem. I've been wanting to build a LT-25 for a while but have been focusing on other projects. I've attached 2 links that I saved for when I get my chance.

I also had a few email conversations with Bernard Cawley (BEC here on EZone) about his LT-25 and his power choices. If you need more info you may want to drop him a PM.

Good luck,

Sep 19, 2002, 01:29 AM
Gravitationaly Challenged
jmelzer's Avatar
Jeti 45/3
Jeti 70 amp ESC w/BEC
APCe 13X8 prop
Graupner prop adapter/ spinner
12 - RC2400s (3000 NiMH might be better)
Aero Vee MM1 motor mount
Nylon LG bolts
Bolt on wing
one servo ( Hitec 81mg) for each Aileron - can be used as spoilers
Top hatch for batteries
AUW - 83 ounces - over 100 watts / pound = about 7 mins
Have fun - This is a great building kit
Sep 19, 2002, 01:30 AM
Involuntary Beta Tester
Check out my build and fly thread as well as the previous resources. I went from a Turbo 10 brushed motor to a Mega 22/30/2. All the details in my thread. The Mega will give you thrust. I'm running 14 3000HV cells. My weight is 88 ozs. When I take off the LT can climb much better than 45 degrees. The glow flyers are impressed. I can't wait to try 16 cells.

My current specs are
Mega 22/30/2
Superbox 3.33:1
14x7 APC prop
14 Sanyo 3000HV
40amp Model Motors 40-16 ESC (same as MGM Compro)

Last edited by kelvin; Sep 19, 2002 at 01:33 AM.
Sep 19, 2002, 03:45 AM
Transfixus sed non mortus
cwalsh's Avatar

Jmelzer : I use the same power system in my SIG Somethin'Extra, nice power package, capable of powerful areobatics for 6 mins. Not unlimited, but almost.


Sep 19, 2002, 10:11 AM
Visitor from Reality
Check out GaryK on his experiences with an AXI2820/10 and ten cells in his Skyvolt. I've seen that one fly, quiet and with plenty of power. Suggests the same rig would power a LT25 well. I've gotten a Cuban 8 out of a LT25 on a geared Magnetic Mayhem on ten cells. Okay, not a big C8, but it didn't drop any height doing it. The AXI would be more powerful and more efficient.

OTOH, if you can run to 16 cells and can fly, why diddle around? Start with a brushless equipped Four Star 40 instead. Great flying model, and it's way easier to build a battery tray and access hatch into a low winged model than a high winger.

If you want peace and quiet over whining gearboxes, there's rumour of an AXI outrunner for 16 cells "coming soon" to the US, or contact Tom Hunt at MAT about his Mega motor / Beltdrive combos. Bit noisier than straight drive, quieter than gearing.


Sep 19, 2002, 11:44 AM
Registered User
fbw4's Avatar
You may want to consider the Hacker B50 13S geared 6.7-1. This is a very popular motor for dozens of planes and gives me unlimited vertical performance in my LT-25 on 12 or 14 cells. Check out my web site for all the information and video.
Sep 19, 2002, 01:45 PM
Registered User
Hi Ken,

I recently built a LT-25 with the AXI motor. here are some links of the build process.

I also have a few short video's of take-off and landings on my website. and click on the e-flight button.

Sep 19, 2002, 02:05 PM
Registered User
BEC's Avatar

I think there are three viable direct drive candidates for the LT-25 right now (read, among other things, readily available in the US). Listed in my guess of increasing available performance without toasting things:

AXI 2820/10 on 10 cells, 12X6 APC-E
(The 2820/12 on 12-14 cells and a prop about the same size - chosen to keep full throttle amps below 35 or so, should also work.)

Jeti Phasor 45-3 on 10 cells APC 14X7E (I've flown this combo) or the 12 cell combo jmelzler reports on above.

Mega ACn22/45/3 on 10-16 cells with appropriate prop choices depending on cell counts.

I am flying a larger, heavier plane on my AXI 2820/10 with the 10 cell system (the JK Aerotech Big T) and it performs much as you describe you would like to see. I am sure it would pull my LT even better (the one in the second link that Bill Germanson points to) but right now it has a Hacker B50L-13 geared in it on 14 CP1700s and can go straight up .

There are bigger outrunners available in the Aeronaut/Kohler Actro line that will do what you want, but there's no US source for them that I know of and the price jump is a big one above any of the three I mention and an appropriate Czech-made (like the motors) 40-50A controller (Jeti Gold label, MGM ComPro, or Jeti/Hacker).
Last edited by BEC; Sep 19, 2002 at 02:08 PM.
Sep 19, 2002, 08:25 PM
Thats gona be expensive
Q-HUNTER's Avatar
You guys are great!
I actually have a 28/20 10 sitting here.
I didnt think it had enough A** to do the job, but I will try that combo first.
And progress from there.
Derek, I just ordered a four star 40. the same time I ordered the LT25.
I was going to wait on the 4star but that may actually go first. Power system should be about the same.
Sep 20, 2002, 12:13 PM
Senior Member unum multum
mudfarmer_mike's Avatar

RE: LT-25

I have thought about using the AXI 2820/10 in my LT-25. I've noticed most of the LT-25 are coming in at an 80+ oz. AUW. I'd like to keep mine around the 70 oz. mark. Do you think this is feasible?
Sep 20, 2002, 02:37 PM
Registered User
edbuell's Avatar

LT-25 Building

My Lt-25 should arrive tomorrow. This will be my first building project. It seems that several of us will be working in parallel.

I appreciate all the helpful tips and hints that come along.

I don't expect to build mine very fast, because I really like to ponder twice and cut once.

This will require some pondering on my part . My plans are to put servos in the wing. to move the tail end servos aft and place the power pack track down the middle. I will proabably follow a bunch of the hints from Kelvin Ritchie's project documented here.

Good Luck

Ed Buell
Sep 20, 2002, 07:41 PM
Involuntary Beta Tester
Keep us posted on the construction. I'm going to recover mine this fall. I'm going to add a fairing on top of the wing adjacent to the F2 former and modify the hatch to cover the motor. I'm going to try to use small magnets instead of hinges.

If you use nylon bolts for the wheels use 10-32. I've had some bad luck with landings and the 10-32 bolt heads will strip off saving your fuselage from having the ply plate ripped out.

The wing blot mod is nice and putting the servos in the wing and direct connections is a nice mod. I may do that also.


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