Another Sig LT-25 conversion....

[Rodger68]

For shooting touch and go's on a Sunday morning in the local school yard it's hard to beat a LT-25. I built mine with a flat bolt on wing and with conventional gear. I also rounded the tail surfaces a little just for fun.
With the below equipment I am getting 15 minute flights flying aggressively and have reached 30 minutes taking it real easy floating around. Take off roll at full power takes place in about 10 feet with unlimited vertical. I love this airplane!
Equipment list for reference....
Motor: AXi 2826/10
Speed Control: JETI 70 plus
Prop: APC 13X6.5
Battery: A123 4 cell (charge in 15 min using modified Astro Lithium charger)
Radio: JR 226X receiver, 4 JR 341 servos, 300mAh Ni-MH rec. battery
Aluminum gear with 3.25" wheels
Klett tail wheel assembly
Flying weight: 4.0 lbs.

Next project is a Skeeter 24" 3D using an AXi 2203/46. Goal flying weight is 6.0 oz!

Take care,
Rodger

[DavidN]

Still flying mine 4 years on. It has 2 piece wing and removable stab for travelling; but I never have removed it. Should have just saved the weight and gone with a one piece wing & fixed stab.

[viva_peru]

Rodger,

Very nice. I also have an LT-25 which I built two years ago for the same reasons. This past summer, it made it out to the field just about every time I went out. It is a very nice flying airplane and very relaxing to fly as well.

Nice job,

Teo

[SKYPILEIT]

We flew Richs' e-converted LT-25 today & it is one of the best all around sport planes ever..!He uses the same motor/ESC/batt combo as Rodger68 & the AUW is exactly 4 lbs.Plenty of power for most manuvers & with full power will fly verticle to several hundred feet.Here's a few pics,the overhead fly-by shows the external camera mount.

[bobf]

I am looking at building a Lt-25. What is the shape of your A123 packs. Is 4s1p or 4s2p. I have 4s packs that are 2x2 that I would like to use.


For shooting touch and go's on a Sunday morning in the local school yard it's hard to beat a LT-25. I built mine with a flat bolt on wing and with conventional gear. I also rounded the tail surfaces a little just for fun.
With the below equipment I am getting 15 minute flights flying aggressively and have reached 30 minutes taking it real easy floating around. Take off roll at full power takes place in about 10 feet with unlimited vertical. I love this airplane!
Equipment list for reference....
Motor: AXi 2826/10
Speed Control: JETI 70 plus
Prop: APC 13X6.5
Battery: A123 4 cell (charge in 15 min using modified Astro Lithium charger)
Radio: JR 226X receiver, 4 JR 341 servos, 300mAh Ni-MH rec. battery
Aluminum gear with 3.25" wheels
Klett tail wheel assembly
Flying weight: 4.0 lbs.

Next project is a Skeeter 24" 3D using an AXi 2203/46. Goal flying weight is 6.0 oz!

Take care,
Rodger

[gwh]

I've flown my LT-25 on both 4S brick and 4S stick packs of A123 2300 cells. Both are 1P and fit fine. I'm also running a Axi 2826/10.

[bobf]

How much run time do you get with just 4s1p 2300 A123 packs.

I've flown my LT-25 on both 4S brick and 4S stick packs of A123 2300 cells. Both are 1P and fit fine. I'm also running a Axi 2826/10.

[gwh]

I normally fly 10-15 minutes but it could be pushed more. I have several packs and don't like to hit LVC with A123s so I don't pay alot of attention to the max time. The 30 minutes mentioned above is possible for gentle flying. I almost stayed up longer that a glider when I was using it for Aero-towing and found a thermal with the LT-25!

http://static.rcgroups.com/forums/attachments/2/5/1/7/a2102478-185-DSC_0050.jpg

[bobf]

Would you know how much current your pulling. With that much run time you must not be running the AXi 2826/10 very hard. They are 4s1p not 4s2p packs?

I appreciate all the input. I think your color scheme is my favorite so far. I wish I could do covering. I am really bad at it, but I have friend that might barter something to cover it for me. I just printed a copy of your plane.

I normally buy ARF's but I want something for a make work project. I have a way to much spare time on my hands being retired.

I normally fly 10-15 minutes but it could be pushed more. I have several packs and don't like to hit LVC with A123s so I don't pay alot of attention to the max time. The 30 minutes mentioned above is possible for gentle flying. I almost stayed up longer that a glider when I was using it for Aero-towing and found a thermal with the LT-25!

http://static.rcgroups.com/forums/attachments/2/5/1/7/a2102478-185-DSC_0050.jpg

[gwh]

It pulls about 50 amps at full throttle but I spend most of my time at very low throttle settings.

I did not build this LT-25. You can read about this one's history in this thread, http://www.rcgroups.com/forums/showthread.php?t=38685

However, I did build one ten years ago when I was doing alot of travel. This is probably the easiest balsa plane there is to build in a hotel room. I built and covered the pieces then checked it in my luggage to come home. I basically had an arf when I got home to finish assembling.

[bobf]

Does the 13" prop give you clearance on a grass field. Are you using the stock landing gear.

[SKYPILEIT]

The AXI 2826/10 & 4 cell A123 pack is ideal for the LT-25,most know these cells have a quick drop-off of amperage after a 6-8 minute flight.To maintain proper control of your plane,it's best to use a small reciever battery...simply use a 3 in. servo extension with the red wire cut,then plug the auxillary pack into the reciever.

[bobf]

I am going with a Scorpion SII-3020-1110 800 watt motor for $69.99 vs Hobby Lobby's $112 for the AXI . I have five Scorpion motors and are very happy with them and their fantastic support. I going to use a 11 x 6 prop. 4s A123 pack.

[SKYPILEIT]

I am going with a Scorpion SII-3020-1110 800 watt motor for $69.99 vs Hobby Lobby's $112 for the AXI . I have five Scorpion motors and are very happy with them and their fantastic support. I going to use a 11 x 6 prop. 4s A123 pack.

Good choice,let us know how it works out.I'm gonna use the 35-48-1000 Electrifly I got at a decent price...good for about 740 watts.This one below.

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXLWU7&P=0

[twest]

Do they make an arf of the kadet 25?

[bobf]

Not that I am aware off.

Do they make an arf of the kadet 25?

I have found a set plans for a 1/2 A LT-25 look a like that I am resizing to 125% gives a wing of 50". I am going try and scratch build it as the LT-25 kit is so expensive. I am also going to try doing a foam core wing.

[gwh]

Tyler,

The LT-25 is almost as easy as an ARF to build. The Sig website does show a Seniorita ARF now.

[bobf]

It appears the LT-25 is very easy to build from every thing I have read. I problem is doing a covering job that matches a ARF is the hard part of any kit build. Lucky I have two friends that do great covering that I can get help from.



Tyler,

The LT-25 is almost as easy as an ARF to build. The Sig website does show a Seniorita ARF now.

[JustPlaneChris]

Sorry to bring an old thread back to life, but I just wanted so share my LT-25 conversion too! :)

It's actually been around for a couple of years now. Details are here:

http://www.justplanechris.com/wordpress/?p=8

Since that time I've dropped from a 5S A123 to a 4S2P A123 and increased the prop from an 11x7 to a 13x8. The combination is nearly perfect! If I were to change anything, it'd be to drop to a 900kv motor (1000kv now).

Sunday I went out and flew on a breezy morning. Even with the wind, after the 15 minute timer went off it would still loop from level flight at half throttle! And that was after 15 minutes of loops, rolls, stall turns, inverted passes, and touch-and-goes. :cool:

To say I'm pleased is an understatement. It's brain-dead easy to fly, and will fly so long one almost gets bored! Top it off with 15 minute recharges (iCharge 208B) and it's a true winner.

-Chris

[hpux735]

I just finished my converted LT-25. I'm pretty excited, but I finished at the wrong time of the year :( Anyway, I wrote a lot about it on my blog (http://alternet.us.com/?p=488), but I'll go over the broad-strokes here.

I decided on the Scorpion 3032-10 motor and a 70A speed controller. It is EXTREME overkill, but I think it'll be alright...
The motor is almost exactly long enough to not need any adjustment of the cowl sides or motor mount. A single thickness of 1/16" spruce between the mount and firewall was just perfect. I'm using the APC E-11x7 prop for now.

I got a new thunderpower 3S 2100 20C battery to go with it.

Here's some pictures for fun!
http://alternet.us.com/wp-content/uploads/2009/11/20091011-DSC_4757-Edit.jpghttp://alternet.us.com/wp-content/uploads/2009/11/20091025-DSC_5031.jpg
Cheers!
- Will

[JustPlaneChris]

Very nice, Will! You will really enjoy it. My poor LT-25 is in need of some major repairs, unfortunately:

http://www.rcgroups.com/forums/showthread.php?p=13425344

-Chris

[DavidN]

Nice Will. I was away when you posted Great close in flying on the vid.

What is your weight with the 4 A123s?

[hpux735]

Sorry to hear about your LT-25, Chris!

I'm concerned about what happened... I just switched to 2.4Ghz (Spektrum), and it sounds like that is related to why you lost the plane. I'm wondering if I should worry about the remote receiver things, or if you think it's mostly a fluke?

[JustPlaneChris]

Sorry to hear about your LT-25, Chris!

I'm concerned about what happened... I just switched to 2.4Ghz (Spektrum), and it sounds like that is related to why you lost the plane. I'm wondering if I should worry about the remote receiver things, or if you think it's mostly a fluke?I've been flying RC for 29 years, and I've had only two instances like this where the radio mysteriously just stopped listening. Once on 72 mhz, and once on 2.4 ghz.

Any kind of radio system has failure modes or can be the subject of interference / lockout. Just install the receiver following the manufacturer's recommendations, range check it, and go. You'll be fine. :)

-Chris

[hpux735]

I've been flying RC for 29 years, and I've had only two instances like this where the radio mysteriously just stopped listening. Once on 72 mhz, and once on 2.4 ghz.

Any kind of radio system has failure modes or can be the subject of interference / lockout. Just install the receiver following the manufacturer's recommendations, range check it, and go. You'll be fine. :)

-Chris

That's good enough for me! Thanks.

[hpux735]

My conversion successfully completed it's maiden flight!

I'm not happy with the propeller at this point, I had to fly at full throttle the whole time, and when I landed and felt the motor it was barely above ambient. I bought a 11x8.5 and 12x7 APC E props to replace the 11x7-E. I'm excited for some more good weather! :)

I made a new post on my blog (http://alternet.us.com/?p=551) that has way more pictures, but here are some fun ones, anyway :)

http://alternet.us.com/wp-content/uploads/2009/11/cartwheel-triptych-small.jpg

Note that the cartwheel didn't damage anything, and the pictures in the air are after! :)

http://alternet.us.com/wp-content/uploads/2009/11/20091114-DSC_5360.jpg

[DavidN]

Check amps & RPM to see wether it is thrust or pitch speed you need more of.

[hpux735]

How would you do that, exactly?

[DavidN]

Use a wattmeter, emeter or data logger to record amps & watts at full throttle. then use a tach for RPM. use any of the electric calculating software & manually change rpm to measured (If you don't have a tach you can change the voltage) This should give you a rough pitch speed. For this plane I would want 50 -60 mph so most is at part throttle. same programs also give watts per lb & thrust. Nowadays I like 100 watts per lb. Thrust 80-90% of weight is good. Climb out less than 54 deg I find doggy. Yhis relates to my experience with ecalc. In power systems there is a sticky of online calculators. Motocalc has a 30 day free trial.

[hpux735]

I haven't gotten around to buying a watt meter, but I did buy one prop with higher pitch speed and one with more thrust (all other things being equal, except current). Originally, I used the APC 11x7 prop, and I tried the 11x8.5 second. That prop is so much better, I'm not really in much of a rush to try the 12x7. Anyway, this is a really fun electric conversion. I love this plane. I can do touch-n-goes for 12 minutes on a single battery (with 11.3 volts left on the 3s pack). That's a lot of landing. I've gotten good enough that I just come down on the mains as gently as can be! :)

[motorhead540]

hi guys great thread my first trainer was a sig kadette 25 lt with a os25fp was a great trainer real floaty had a bad cross wind and cartwheeled and broke tail off repaired and flew again but that was on gas now i fly both electric ,nitro and gas i have a sig cobra i have been contemplating doing as an electric conversion any ideas

[hpux735]

There are many ways you could go with it... I like that the E-Flite Power series of motors are rated for what they replace. It makes it easier when you can just get a Power 35 and be done with it. Otherwise, I really like my scorpion motor. Another way that some people start is by figuring out the prop they'll use with it, either by math or recommendation, and choose a motor based on that.

Good luck!