Location Of Main Gear for a Taildragger Conversion - RC Groups
Jun 18, 2002, 12:49 PM
Registered User

Location Of Main Gear for a Taildragger Conversion

I am looking into converting a tricycle gear trainer I have into a taildragger and want to know what the formula is for figuring out where to mount the main gear in relation to the CG and leading edge of the wing?

Thanks,

Mike
 Jun 18, 2002, 01:25 PM God is good As a general rule, the center of the wheel hubs should be at the LE. VP
 Jun 18, 2002, 01:33 PM Hey, I wanna fly too! Mike, I don't know any formulas, but a few of the tail draggers I have in my hanger all have the gear +/- 1/2" from the leading edge. This covers anything from a Champion (+1/4"), E3D (+1/2") to 60" Shoestring (-1/4") or GEE BEE R2 (0") Terry
Jun 18, 2002, 02:07 PM
Ascended Master
Generally I place the mains so the front of the wheel is visible when looking down at the plane..
This is close to the leading edge, as on this Seniorita...

Images

 Jun 18, 2002, 02:23 PM Registered User Here's the guidance from the book, "Basics of RC model aircraft design". With your plane in a level attitude, and at a height that gives you your desired prop clearance, draw a line straight down from a point on the bottom of the wing at your forwardmost cg straight down. Now draw another line downward from that same point at an angle of 15-20 degrees from the vertical line toward the nose of the airplane. The contact point of your wheel will be where that second line touches the ground. The center of the wheel is located dierctly above that spot. Sorry for the long explanation, but I'm trying to describe this from a drawing in the book.
 Jun 18, 2002, 04:51 PM Registered User Thanks guys! Sounds straight forward enough. Now I need to figure out what tail wheel I am going to use....
 Aug 22, 2017, 10:34 PM Registered User HI, I did the conversion and the landing gear is now about 2 inches behind the wing? so where would I find the CG, now? Thank you . Tried to taxi it and it just nose dives when power applied, so the CG, is way off>? should I get a CG , tool? or is there some measurement form the wheel to leading edge? Thank you all
 Aug 22, 2017, 11:00 PM Registered User This is not a CG problem, your landing gear is too far back. Read the second post in the thread, for sport models it can be a bit more forward Pete
 Aug 22, 2017, 11:06 PM Wake up, feel pulse, be happy! Two inches behind the wing? I would remove the landing gear and re-attach in a more sensible location. Changing the CG position to account for improperly placed landing gear is like injecting the patient with pineapple juice because we ran out of blood transfusions.
 Aug 22, 2017, 11:23 PM Registered User Make mine type O, daddy-o5 Pete
 Aug 23, 2017, 12:51 AM Registered User Wow, the OP of this thread posted it 15 years ago!!
 Aug 23, 2017, 09:26 AM Registered User Thank you for the input. I understand, However on the NExstar, I followed a conversion on this site, that others have done. They all suggest the landing gear, to be placed against the back of the fuselage, against the gas tank, There is no other place to attach it, without taking the whole plane apart. Anyone who has done the conversion that was shown in this blog , have any input for me. thank you .
 Aug 23, 2017, 09:39 AM I miss President Reagan Got a link to that conversation? I suspect you didn't fully understand it. Simply put, with the fuselage in a horizontal position, i.e. as if it were flying. Place the axle for the wheels directly below the leading or front edge of the wing. Place it far enough below to provide the necessary propeller clearance. How and where you attach it to the fuselage is up to you. Most kit built tail draggers have either hard wood or plywood supports in the bottom of the fuselage the landing gear gets bolted to.
 Aug 23, 2017, 08:06 PM Wake up, feel pulse, be happy! Here's the conversion thread https://www.rcgroups.com/forums/show...ger-conversion Here's a picture of the model in question.