pcbprotool

I have a friend who just finished his new Sig LT40 following the plans he made it into a trike. The air field he has found that is nearest him has a grass runway, they are saying he may want to convert his LT40 trike into a taildragger. If what they are saying is true can someone post the way to convert this.

ag4ever

I have seen some people post about using larger wheels, don't know if that will work for your friend though.

To convert to tail dragger, I would remove the trike gear, get a new front gear made out of flat aluminum stock and mount it just slightly in front of the LE (reinforce the heck out of the mounting location and install blind nuts from the inside), then get a tail wheel assembly and install it at the rear with pull-pull controls.

bkdavy

My Feedback: (1)

Its easier to just use 3 inch wheels. As long as the grass is cut short, the trike configuration with larger wheels is fine.

Brad

pcbprotool

The LT40 comes with 3 inch main wheels and a 2-3/4" front wheel. Maybe they run smaller planes and need the tail dragers to help get them up using smaller wheels... My airport has both an asphalt and grass runway. I had no problems with my LT40 going either on grass or asphalt. We may go visit the field and take a look ourselves and see if they even roll the field after the ground thaws out. I'm in Maine and we have some pritty rural areas up here...

dredhea

My Feedback: (13)

It just happens that the local youth aviation program here just did this conversion last year. Since the gear needed to be repaired anyways, (some students don't get the hang of landing down as quickly as others) we decided to make the change. The key here is that we DECIDED to make the change. Our runway is one of the roughest grass strips around, and the LT got off from it just fine. We add stronger main gear to ours to accomodate the abuse we put them through, and simply go up about a half inch in wheel size to handle the rough strip.
If you want to go with a taildragger version, simply move the main gear forward a couple of inches (how far is not critical as long as the gear is in front of the CG) and add a tail wheel that is connected to the rudder for steering. Be sure to reinforce the fuselage where you mount the mains, but I personally would not use blind nuts to install the gear. I recommend wood screws of appropriate size. A hard landing will then tear the gear off rather cleanly, making the repair much simpler. Blind nut/bolt mounting tends to lead to the entire bottom of the fuse getting ripped apart in a landing mishap. Be sure to rebalance the plane after any modification. Happy flying

AA5BY

The placement is important because it affects the way the tail starts flying on takeoff. Wanted is a location that doesn't allow tippy taxing but will allow the tail to fly reasonably quickly. I'm building the LT-25 right now and it is a dedicated tail dragger kit. The center of the mains is 3/8" back from the leading edge of the wing. Upscale that for the LT-40 and perhaps 1/2" would be close.

I would go with blind nuts and aluminum landing strut. I understand the argument about the wood screws however and it raises the issue of at what stress point is the program failure desired? IMHO... wood screws will fail too easily on a landing that the gear should handle. The advantage of the aluminum gear is that no torsion rod supports are needed, which allows the plywood support to be ripped free in a generally benign fashion that likely simply requires re-gluing. That will happen upon a much harder stress than wood screws and if very small blind nuts are used, it could be that they will pull out and only need relocated in the plywood. Of course going with wood screws might allow a couple of moves while blind nuts might allow one.

Hooking the tail wheel steering is not as conventional as on most models because of the forward setting rudder. The LT-25 uses pull/pull wires hooked to a plywood bell crank set on a cross member a little aft of the servo tray but I see no reason why the wires can't be hooked directly to a long servo arm outboard of the rudder control rod.



At any rate,

John Sohm

My Feedback: (9)

Our field is pretty rough most of the time and there's one thing I can say about trike gear ... It's pretty hard to nose it over and break a prop when a wheel does get stuck in a rut but that isn't so true with tail draggers (or more correctly, conventionally geared aircraft). If your friend is a beginner, I'd suggest he increase the size of the wheels from 1/2 to 1 inch in diameter and use the light weight type wheels. Trikes are better handling on taxiing and takeoff runs until rudder kicks in. I don't think too many will dispute that point.

As for wheel placement should he decide to convert to conventional... The main gear will need to be located a bit forward of the balance point but not so far forward that the tail is hard to come up. Decent rule of thumb is however far behind the balance point it is in the trike config, it's ok to have it that far in front of balance point in taildragger config. Hope that makes sense to you.

If it were mine, I'd just add the bigger wheels. Just use the light weight types. Dubro and Sullivan both make that type wheel. I'm not talking about those all foam tires, although they would also work on grass.

Insanemoondoggie

Sig made a LT40 k2 I think was the #, but it was a tail dragger. I converted mine this week and set the stock landing gear up in the same location as the K2, right behind the first fuse former.
I added a tailweel I had to modify and ran an extra push rod tube to it off the rudder servo..
I`ll post a few pics latter today, give you a better idea and also find the link for the LT40 Tail dragger page.

pcbprotool

I really don't know what the big tado is regarding tail draggers. I've flown both tail draggers and trikes for years and would rather fly trikes. I built an Astro Hog and built it as a trike, it has never tipped over or anything. I realize the rough grown can have an effect on this but all in all to me trikes are better. When I fly my Areonca Sedan I have to give it full rudder to keep it straight, maybe I need to bend the tail wheel a little ...lol
You can see my astro Hog in the back ground as I'm carring my Sedan to the field. So maybe these guys are the guys who swear by all planes must be taildraggers...

jollyroger

My Feedback: (6)

I use a DUBRO fiberglass Lg with 3" tires and Sullivan tailwheel assembly connected by pull/pull wires. which in turn connected to rudder servo.

rctrax

I would use aluminum gear and place it about 1" ahead of the leading edge of the wing setting level. Otherwise you will nose over all the time . Also I always use nylon bolts for the landing gear[1/4-20] and tap the screws right into the wood[no blind nuts] This will allow the gear to shear right off with no damage to the fuse, and all you need to do is screw the broken studs out and remount the gear with new nylon bolts and your ready to go again.

dieFluggeister

Sorry, I'm a little late to the post but I just saw it poking around tonight.

I did a conversion a while back at this thread:

http://www.rcuniverse.com/forum/Conv...2524324/tm.htm

I ended up using skiis in the winter and 3" wheels in the summer for the grass field. The location of the wheels in relation of the LE of the wing is just right for me - I have never had a nose over.

Edit-added pics

pcbprotool

this was what I suggested that he make on his model, to put the wire into the rudder and use the existing clevis, make a notch and attach. Looks like you did a great job in retrofitting this from a trike to a dragger... good job. We are going to try the trike first and if he has problems he will change his to the set-up you have...

Thanks,

pcbprotool