lazyace

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OK guys I have a set of jerry Behrens 1/4 scale sopwith triplane plans and inst. manual , had the kit cut , been reading the manual 3 times and looking at the plans till I about go blind , but I can't find the cg or any wing incidence's , any one have any idea's , engine size ?

thanks charlie

Hurri

Charlie . I have a 1/4 sopwith tri plane I drew it up myself , its 2 years old . have a 26 cc zenoah for power with a n apc 18-6 w prop . flys great for incidence it is flat across the bottom of the wing , like in a clark "Y" section , so think that is 2 degrees positve ?weight is 17 lbs balace is at back of the cabane on top wing 4-1/2 " from LE . I had it a away back at 1st another 3/4 " but got rid of a lb of lead to get it where it is now . I have rib stitching on wings . legit full size bungy on the axle for the l/gear . Hurri

abufletcher

Today I received the Tripe drawings that I ordered from Replicraft. Man are those something else (like all the other sets)! I'm thinking of enlarging them to 1/4 scale (124% increase to fit a 26cm aluminum pot for the cowl).

lazyace

My Feedback: (126)

hurri

thanks for the info , I used the mac system and at 28% comes to 5 1/8 back from LE top wing is that to far back ? I was thinking a DLE 30 for power with a 18 x 8 xoar prop , any pics of LG ?

charlie

TFF

Incidence is relational, so all you have to do is draw your own relational lines on the plans for stab and the wings that will be easy to measure on the model and note the angle differences.

abufletcher

I've asked this before elsewhere, but is there any reason (other than "tradition") that a 1/4 scale or larger model can't just use exactly the same incidences (wing and tail) as the original? Assuming one is also using a scale airfoil.

TFF

For the most part you can use scale incidences, but for a model the scale incidences are too much for what is needed. More incidence is a way to "cheat" and get more lift out of the wing while the fuselage is level. We dont fly at scale weight and for the most part physics wont let us, so we need less "cheating." Bigger the plane the more incidence can be tolerated. When a plane climbs crazily with power and always has major trim changes on the elevator with different power settings, it is because the incidences are not in the best locations. A lot matters if you can tolerate it as a pilot, too.

Richbailey

Richbailey

mgnostic

Since the stagger on the Sopwith is evenly spaced you can still use the calculation of mean aerodynamic chord (MAC). If you balance at 25% of this measurement it should give you a mildly nose heavy model. Since you are building 1/4 scale you might look to the first few posts of this thread where others discuss the balance points of their 1/4 scale tripes.

Richbailey

Richbailey

mgnostic

I don't know, aside from your post, how far along you are with your build but there is a builder here with the handle Foodstick. He seems to have had good results with 1/4 scale electric conversions.I'm sure I'm not alone in wanting to see a photo of your project.

foodstick

This is a plane on the IF I LIVE LONG ENOUGH list ! hahahaha

Would make a great electric plane. And pretty cheap to do it.

Richbailey

Richbailey

foodstick

Rich, not an Apple guy here, but I hope you can find a way to post your pics..