BadAzzMaxx

Thanks for the reply,
I am installing a 30cc engine and going to install two servos in the tail for the elevator and maybe I can get it right without adding any weight to the tail.

Milton

redball8

My Feedback: (128)

Pranged my Cub while doing touch-n-go's, and she's now in the shop getting the roof repaired. Found a source of cheap wing tubes - Tent Pole Technologies http://tentpoletechnologies.com/?page_id=17. They make tent poles (duh) and masts for RC sailboats. I bought two 26" 19mm (0.742") tubes and one 26" 11mm (0.433") tube from them for less than $25 shipped - enough for two wing tube sets. They're very light, and made of the stronger 7075 alloy (vs 6061). The main tube is a hair smaller than 19 mm (18.9mm), but fits just fine.

bikerbc

cowboy1969 I tried the O Rings and found they worked okay but still deteriorited fairly quickly so I started using 1/8" shock cord (bungie cord) the same stuff found insided tent poles... It works great.. Lasts forever ..You can buy it up here in Canadian tire stores..You cut about 21" length and tie the ends together and CA the knot then wrap it where the O rings were , You sort of adjust till you get the tension rite..You will never look back..

Prekin

My Feedback: (19)

Hi all, I know, this thread is old but I want to ask you, how do you solve question of fuel tank mount? I don´t like the solution which you can find in istruction manul.
I have H.K. Piper L-4 Grass hopper, but it is the same ARF kit as CMPro Piper J-3 91".

rjpmodel

My Feedback: (2)

This thread is Very Old but I have just received a CMP 91” J3 cub and am totally confused about the CG. The cg has been described several times on this thread as 100mm(3.94”) and on the spar. The front of my spar is at 109.2mm(4.3”) and the center of my spar is at 119.2mm(4.7”) ???????

rafeeki

My Feedback: (11)

The c.g. on most straight wing planes is in the 25-30% of the wing cord measured from the leading edge. You will find the main spar within that range.
it is advisable to have the fuel tank at c.g. or forward
good luck

rjpmodel

My Feedback: (2)

Thanks for the reply. The center of the spar is at 35% and the front edge of the spar is at 32%. There has been some comments on another thread that the cg should be 97-104 mm. 100mm would be at 29.4% but they also stated that this would be at the spar and my spar is at 119mm(35%). This is why I am confused. I hope that someone that has successfully flown this plane would state where the cg was set.

rafeeki

My Feedback: (11)

You should try balancing the plane with the fuel tank empty.
The 25-30% figures I gave u are a good starting point... Don't get hung up on the slight differences u mention.
just have an experienced flyer try it out for the maiden flight , less disappointment.

matitatensis

Does anyone have the blueprint for the cmpro piper j3cub 120??? I just broke mine.