I'm finishing a 1/5 scale piper cub and want to gain some experience at flying a tail dragger before I fly this plane. I'm hoping to convert an easy fly 40 trainer to a tail dragger for this purpose. Anyone have ideas on the correct relationship between the CG and the location of the front axle mount?

I appreciate any advice I can get.

Thanks

Conventional wisdom is the main gear axles should be even with the leading edge of the wing. It's not mission critical, but if it's too far forward it makes it harder to handle on the ground.

Thanks for the tip, I appreciate conventional wisdom!

FYI, I found this quote:" a full scale taildragger formula says that a plane must balance on its main gear with the thrust line 15-20 degrees above level." Make sense to anyone?

what that means to me is you run a line down and 15 degrees forward of the cg, and put your lg axle on that line. But that assumes you have an engineer who has figured the cg location in three dimensions, which is cutting a bit too fine for rc aeromodeling. Axle below le is a pretty good rule, and cg 25-30% back from wing le comes out to about the same thing.

I converted my LT-40 to a taildragger. Forget the complicated equations! Just chop the gear and move it foreward of the cg a ways. Your eye is the best measureing insturment, so just make it look good. stick a tailwheel assembly on the back end and you've got a taildragger.

Balsageek's post is right on in my book. It would be nice to keep the wheels axles even with the leading edge but..??? Here was my conversion. Now keep in mind, my ground handleling with the tri-gear usually brought some chuckles. My gear ended up, FORWARD a little bit, of the "rule of thumb" placement,because that was the best place to install the gear mounting block. Like you I was going to taildraggers and wanted to get my feet wet on my trainer which was a Hobbico SuperStar 40. I even rigged a steerable tail wheel. I know these experienced pilots might be correct about the placement of the gear too far forward of the wing's LE .... BUT you couldn't prove it by me. My ground handleing was no longer a joke at the field. Your tip overs will also be minimized. I did pick up some weight, but my trainer flew BETTER with the conversion than before. I don't think you will be disappointed. Just BE SURE you rebalance your plane.
.......lownslo

Bob

lownslo or anybody - When you say you "even rigged a steerable tail wheel" how sould you steer at slow speeds with out it being steerable? I've seen some old planes with just a wire to hold the tail off the ground but I don't know how they "steer".

don't know how they "steer"--

With any forward motion, even at slow speed, prop blast on the rudder will move the tail to one side or the other. Works fine, just needs a little punch on the throttle to move it around.

In regards to pieguy's question about steering...majortoms answer is OK. (sometimes)!!!
The problem comes on grass fields like I fly from. I posted a question about this before I converted to the taildragger and I received about 50/50 yes you do, and no you don't need a steerable tail wheel. Not only is it harder to turn with just a skid or a "castoring" tailwheel on grass..... add to that the smaller surface area of a trainer's rudder compared to an aerobatic low wing plane and it makes it very hard to turn by just the prop wash accross the small rudder surface. I think the Sullivan wheel is very good and much easier to install than running a control rod. The problem with most trainers is the configuration of the tail feathers does not allow for an installation of the Sullivan wheel. Again, majortom is right on if the plane has good power and a fairly large rudder. I have seen several guys at our grass field with just a skid have no problems. lownslo..

Bob

Just a small point......
You fly a taildragger from chocks to chocks.....Up evevator is a must while taxi-ing the airplane....To taxi down-wind can cause a lot of nose-overs...
Good luck
5

A steerable tailwheel is a must at our grass field. I just ran another pushrod to the assembly. It really wasn't that big of a deal. Just a little glueing and covering....


Matt

Have a look at this thread. There are pics, of a conversion I did.


http://www.rcuniverse.com/showthread...407&forumid=22


Just make sure your wheels are at the front of the wing and you should be fine..

Hi Magnum, I looked at that thread. What kind of Highwing ARF is that. Even without the wing I like it's looks. lownslo

IT's the Super Frontier Senior from World Models...


http://www.airborne-models.com/html/supersenior.html


Very nice flying plane. I used a Magnum 91 on it. It's more than the box says, but I did contact the mfg, and they said it would be no problem using the larger engine. The plane actually flies better with it, especially in the wind

It's more expensive the the average trainer, but it's also bigger which means it can handle the wind a little better.

I will see if I can find a before and after shot with the wing, it may be on my other computer.