Cub J-3 Expert Needed

[Gregor77]

I am asking anyone with J3 cub experience to assist in a maiden of a 40-60 size cub.  I have flown small ones.. I need some assistance to make sure it is set up OK and balanced correctly.  This request is for spring of 2013.  Lol!  A bit early, but I am excited about this one.

[piker]

I nominate Glenn or Michael...

Both have flown WAY too many Cubs 

[Michael]

I'll help.

Just make sure the CG is where it is supposed to be, and that there is ample rudder throw.

[Gregor77]

I'll help.

Just make sure the CG is where it is supposed to be, and that there is ample rudder throw.

My issue is that this is a "No Name" cub, but seems to be roughly 40 size clipped wing.  Not SIG, Not H9, Not topflight.. Ron thinks it was a goldberg kit.  I am going to throw a HK power 60 on a 5S, 4000 pack.  Servos are HXT std servos and should be more than enough for the plane.  I am using the C/G that is 25% of the Wing on the spar to start with.  I recall Ken Coleman telling me my Areonca champ was nose heavy as it always came in hot.  This plane is very similar in design. 

[Frank v B]

Greg,  first of all, there are no experts.... there are only people who have learned from their mistakes!  I have maidened about a dozen Cubs (12 mistakes! ).  My advice

1) take the forward CG on the plans and move it forward about 1/4".  If it is too nose heavy it won't take off.  If it even smells tail heaviness it will be uncontrollable.

2) On the first take-off attempt, if it tracks straight, take off but do not turn until you have 2 mistake-high altitude.  Once two mistakes high, initiate a turn with aileron and rudder.  Do not rely on aileron only.  A true Cub needs rudder to kick the ass end around a turn.  Otherwise it drags its back end through a turn.

3) If on the straight take-off run the tail starts to wallow from side to side, cut back power immediately, do not initiate a turn of any kind and ditch it in a straight line.... even in the rough if you have to.  Move the CG further forward and try again.

Of all the planes I have flown, the Cub is the toughest to maiden because it has a mind of its own.  It flies fine once the maiden is out of the way and it is properly trimmed.

For what it's worth.


Frank

[Bobmic]

SPRING 2013...? Are you joking just bring it tomorrow to the field and start from the second flight.
Now seriously if you end up with not the best maiden flight, the snow will help cushion the fall and you will have time to fix it so by spring you can actually enjoy it.
I will also take a video of your maiden and that way you can analyze it during the rest of the winter.

..so what time tomorrow ?

[Frank v B]

Greg,

Dug up a plan for the Great Planes Electricub.  It has a 58" span.  The CG is 2 11/16 back from the leading edge on a 8.25"chord (31.8%).  A good starting point for your plane will be 31.8% of the root chord back from the leading edge.

About erring on the nose heavy side- I had a Herr Engineering Cub (48" span) with a geared speed 400 and could never get it to fly properly.  It wallowed all over the place.  Cut off the nose and put in an OS .15, super nose heavy and it flew great for several years until the motor was tired of pulling along a Cub and broke off.  Separation anxiety I guess.

Frank

[Gregor77]

Frank

The plane is now completed with tundra tires.. At 31% it is nose heavy.   This is what I wanted to start with.  I know that the E-flite J-3 has very tame elevator travel rates.  I am going to try the same on this one.  The tail will have a highter rate just in case.

Now... here is a question.  I am running a power 60 eq with a 5S, 4000.  What if I doubled up the packs to 8,000 mah.   You think it might be too heavy?  The C/G didn't really change much...  I moved the packs closer to the center of the C/G.

Well if it was not -22 outside.. I would be at the field tonight...

[piker]

Without knowing the specific plane, I'm still pretty sure you could get away with the extra pack.  But to know for sure, what is your wing loading and power loading?

[bfeist]

I wouldn't recommend maidening with a higher wing loading. Another aspect of a Cub is that is flies extremely slowly, and in my case I find that I was constantly afraid of tip stalling at first because it appears "too slow". Add to that the fact that Cubs don't have gentle stall characteristics, they dive and spin. Until you get to know the plane and practice stalls at altitude, you won't know how a higher wing loading will affect the flight characteristics.

I realize that this advice and the last few posts make Cubs sound terrifying. They aren't. They're just a combination of looking as though they are about to stall, plus needing to flying them with all controls (to Piker's point). Once you learn to trust the plane you'll have piles of fun with it and will be doing all sorts of things like trying enormous batteries and 40 minutes flights of touch-and-goes etc. Just don't try it all at once and take it very conservative on the first few flights.

My own stresses in the past with cubs were only because I expected them to be high-wing trainers but they aren't. I fought with my eflight supercub for half the summer before dialing in the CG and learning to trust it. Now it's one of my fav planes--that reminds me, I need to get cracking on that lighting system in mine!

Ben

[Gregor77]

Well, I flew the grasshopper for the summer.. Mind you it's small.. But I got used to using rudder for most of the flight.  The thing is that it reminds me of a DR-1 in the way it fies.

[Michael]

I saw the video of you flying the Piper Cub on floats from the snow at TEMAC.

You seem to fly the Cub just fine. Just make sure you use rudder in all turns.

Also, I noticed your takeoff was sluggish. Many flyers add a cell and reduce prop size (keep the amp draw the same) when using floats.

[Gregor77]

I was afraid to jump up in the air to fast.  That is why I had to long run out.  I am running a 10x7 prop on 4s. I can run 11 mins on a 2600 pack. I will still have 800 in the pack. 

[Michael]

No problem then.

Your flight was great!

[Gregor77]

Thanks!  I had another good flight with Gerhard and Ken yesterday.  My friend John was there also.  We just missed Ed. It was a bit more wind compared to Saturday.  Colder too.  Just did 4 mins and landed.