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-   -   J3 cub, crash on take off nearly every time. (https://www.rcuniverse.com/forum/crash-rebuild-96/6464055-j3-cub-crash-take-off-nearly-every-time.html)

LouisB 11-14-2007 01:30 PM

RE: J3 cub, crash on take off nearly every time.
 
All the postings mentioned "balancing". Some people like myself might think that you are referring to centre of gravity balancing. With a deceased Phoenix Sonic low wing I've learnt you have to check the CoG AND the wing lateral balancing as well. Because its an ARF does not necessarily means both wing halves are the same weight. My Sonic also had the tendency to drop the left wing and after a few crashes it dawned on me to check the wings for lateral balancing. Took 5g of lead on the right wingtip to rectify matters. After that it flew beautifully but cartwheeled on a too slow approach. With all the previous crashes that was it.

JPANN 11-14-2007 02:54 PM

RE: J3 cub, crash on take off nearly every time.
 
LouisB,
How did you check the wing for balance? I have often wondered how everyone else does it.

skydeuce 11-14-2007 03:03 PM

RE: J3 cub, crash on take off nearly every time.
 
JPANN,

I certainlay applaud your resiliency in flying that Cub. Some planes just don't want to fly no matter what you do to them. I learned an interesting thing with my Cub (that happens to be a Green R/C ARF, 71" span, .52 4-stroke) this past weekend. I was commenting about how much rudder it took to get the thing to turn when an old timer provided some valuable input. He had me adjust the ailerons so they had differential throw, that is to say they don't deflect down as much as they do up. I have mine on a Futaba 9C so it was easy to do. I separted the ailerons and put on two channels and activated the Ail Dif function. Then I reduced the down throw on each aileron to 50% of the up throw for each. As the old timer explained, when a high wing, fat chord plane like a Cub has equal aileron deflection, the down deflecting aileron is only really producing drag and not a roll force. Now, it flies really sweet and smooth and is great in the turns. I also have 20% exponential set into the ailerons and elevator servos so that they are not as sensitive around the center. Easier on the landings...

Hope this helps,

Eric

JPANN 11-14-2007 03:46 PM

RE: J3 cub, crash on take off nearly every time.
 
skydeuce,
Thanks for the info, I believe my radio is capable of this as well and I will certainly try that next time I get one up (provided that I am smart enough to actualy program it correctly). I honestly appreciate all of the advise given in all of the posts thus far. My only regret is that I did not come to all of the people who have given ideas and advise without hesitation before I mutilated the airplane. I have learned a great deal however and will sincerly try to do a better job of it the next time. I hope that in the future I can be like one of the many here and give some of this advise and lessons to others who may need it. Kind of cool how all of that works!

Thanks again,



Villa 11-14-2007 04:57 PM

RE: J3 cub, crash on take off nearly every time.
 
Hi LouisB
To check the right/left balance on my CoroCub, I fully assemble the plane, then I grab the prop at the top and grab the top of vertical stab. I have zero right/left thrust on the egine.

Johnnie Red 11-15-2007 07:50 AM

RE: J3 cub, crash on take off nearly every time.
 


ORIGINAL: JPANN

Johnnie Red,
That is a valid point / idea. We checked the diff. between the new cub and the one that is no more and the new one has almost exactly the amount you described verses the spent cub. I am thinking the new one is good to go as is. Would you agree?
Dear JPANN,

If you put the right thrust + the downthrust your plane should be as tame as a taildrugger trainer. Nevertheless there are some extras that you should also think of making just before you attempt your next flight.
1) Put dual rates on the elevator and ailerons. ( 1 setting on small throws 50% and one setting on normal throws)
2) Put differential ( Because Cubs have Clark airfoils and 0% dihedral tend to yaw when you try turning on ailerons) With differential you eliminate this tendencies.
3) All pipercubs are semiscale - or scale projects; and all scale projects have some vices inherited from the real prototypes. So all the mentioned above are the same troubles that were inflicted also to the real 1/1 Cubs.
Louis's comment is of a use in symetrical or semisymetrical airfoils on heavy birds or on pattern flying. Here the weight is not of the essence since Clark airfoil has the best ability of high lift..(cubs even are used as towing glider planes...They do not have significant problems with heaving a little more weight to handle..)
Exponencial on the sticks are apt to be used from people who have tendencies of jerking the controls from frustration or stress. IMO the sticks should have the normal throws in normal sequence. This is the only way to learn exactly how much you move the sticks in micrometric moves later while you will fly gently heavier, morescale like warbirds or jets.
These are my 2 cents brother, I wish you all happy flights with no more breakdowns on your next projects.
Kind regards
Johnnie Red

JPANN 11-18-2007 01:00 AM

RE: J3 cub, crash on take off nearly every time.
 
Villa,
I landed today using the landing gear you have mentioned above, it did not go so well. I will admit that the airplane came in a little faster than I would have liked but I have done this same thing before with no real problems. As soon as the wheels touched the ground it ripped the bottom of the fuse right out, taking some of the wood by the tail out with it. I had the landing gear attached via four screws to the only piece of plywood in the front of the plane. This is the same ply is where the factory landing gear attached, its about two to three inches front to back and the width of the fuse. I figured for sure if anything was going to give, it would have been the screws holding the gear to the ply. It appears that there was not alot of glue applied to this pc of ply and it did not crack at all it just simply came apart. This made me extreamly angry as this was the first time I have flown in a while and it flew great I had lots of fun for a whole ten min or so until reality came crashing down, literally.

This made me wonder if any of you had a good fix to this problem? I imagine if I put it all back the way it was I will be telling you this all over again. I think it is possible that if I glue the crap out of that pc of ply where it attaches to the fuse this may not happen again. Is there some way I can attach this gear in such a mannor that it would "break away" without taking out the belly of the plane with it if the landings are not perfect? I hated the stock gear because I was fixing the cheap balsa skirts, that gave the wire type gear support, every time I landed. I do think however that the gear never broke the airplane because there was some give to it.

airbatic 01-07-2008 02:14 PM

RE: J3 cub, crash on take off nearly every time.
 
What you should do?

Change friends.

Kraus

Villa 01-07-2008 04:17 PM

RE: J3 cub, crash on take off nearly every time.
 
Hi JPANN
From what I have seen, most planes have a landing gear attachment point that will rip out a fter a few rough landings. After ripping out many attachement points I have learned to reinforce that area very well. For a while I would then also use nylon bolts rather than steel bolts to hold the gear on. Then someone here pointed out, and I now fully agree, that when the nylon bolts break off the gear may destroy the bottom of the plane. I'm back to using steel bolts. Since I land/takeoff many times during every flight, I pay a lot of attention to my landing gear. Most people only land once during each flight. Did your Dubro fiberglas/carbon gear survive? Mine is still doing great.

Yaniel 01-08-2008 10:39 PM

RE: J3 cub, crash on take off nearly every time.
 
reading this thread reminds me of my dreaded cub... after flying electric planes (sport, deltas, 3d) for a while, i decided i wanted to try a glow plane. I bought a h9 j3 cub 40 pnp just to save the hassle of assembly. i crashed it twice when it snapped on take off from not giving it enough of a roll out. I finally got the take offs figured out when it tip stalled and spiraled about 100 feet into the ground. Later that day i decided to fly my friends hobbyzone super cub, hand launched, rolled right, then nose down into the ground. Cubs and I dont get along AT ALL

I gave up, took all the parts out of it and put them in a pulse xt 40 and havent had a single problem flying it. I have the cub sitting in the shed waiting for repairs. One day i'll get around to it and finally conquer it.

Villa 01-09-2008 12:51 PM

RE: J3 cub, crash on take off nearly every time.
 
Hi fstblkgti
Learning to fly a cub will make you a better flyer. I love mine even though it seems to have a mind of it's own. A lot of our models are not much of a challenge. The cub is the exception. Every now and then one of our members builds one. They don't seem to last long befor they are a pile of sticks. Mine now is a SPAD so the occasional horrible landing is not a problem.

Yaniel 01-09-2008 02:43 PM

RE: J3 cub, crash on take off nearly every time.
 
cubs are deceptive little things. high wing, slow flight... must be easy right? WRONG!

JPANN 01-17-2008 10:35 AM

RE: J3 cub, crash on take off nearly every time.
 
Villa,
My gear did survive, without a scratch as a matter of fact. I also reinforced the attachment area after the last landing. The reason that the gear failed was because glow fuel had found it's way inside the fuse and somehow under the covering on the bottom of the fuse. The amount of fuel that had reached theese areas was very little but the oil is nasty enough to "seep" into the cracks and joint areas of the ply / balsa right where they are glued together. I have learned that you should take the extra time to apply glue to the areas mentioned above when you are assembling the plane for the first time (this is even more critical if you have an arf because they only apply enough glue to hold it together for shipping it seems).

We have created new landing gear consisting of good size wire and sodered together with copper wire. It is a great combination of strenght and yet it is flexible enough to take some hard landings without tearing out the bottom of the fuse.

fozjared 01-17-2008 01:18 PM

RE: J3 cub, crash on take off nearly every time.
 
cubs are one of the trickiest planes i have ever seen or flown! surprised me how difficult it was to fly!

adamjedgar 01-19-2008 10:51 PM

RE: J3 cub, crash on take off nearly every time.
 
Cub hard to fly???? bull. That is an absolute load of crap!!!

The very design of this model makes it completely the opposite...

adamjedgar 01-19-2008 11:10 PM

RE: J3 cub, crash on take off nearly every time.
 
1 Attachment(s)
Cub hard to fly???? bull. That is an absolute load of crap!!!

The very design of this model makes it completely the opposite...

It has a long tail moment
relatively high aspect ratio
Is high wing (low centre of gravity in relation to wing)
Large tail surface
And finally, virtually a flat bottom wing!

To those who can't fly such an aircraft i say, "take up lawn bowls cause you're a bit unsteady on your feet and flying RC's isn't for you"!!!
I used to throw mine around the sky like a cork (well a stately cork that is... cause she dont exactly have rapid roll, yaw and pitch rates)

Your mates problems with his cub probably relate to its construction and engine size than anything. I wouldnt dream of flying a 66" span cub on a 50 size nitro engine...it isnt powerful enough for this model. I had a 66" span cub with an asp 61 abc in it and the model flew like a dream, but i wouldnt have dared trying a smaller engine. My cub was only the second RC model aircraft i had even flown and not long after building it I lost an entire port side top wing skin and flew back and landed barely working up a sweat in the process (although i might have had a brown spot or two in my pants due to the shock of seeing that much covering material fall off an airplane all at once though:eek:).
Im sorry for the demise of that cub, its a real shame...but it happens!!!

i got a loss for you, ever seen a $3000 c130 turn into a helicopter??? Mine did!!! Lost engine on right hand side during a banking climbout (was doing a go round) at about 25 feet. I wouldnt have thought it possible what happened next...she went round that fast and that many times i got dizzy just looking at it from 30 metres away(i did reduce throttle on opposing outer engine but it was way to late at such low alititude recovery just wasnt going to happen! Picture dont look to bad, but fues is a write off (an the engines are covered in swamp crud!!!:()

Yaniel 01-20-2008 07:35 PM

RE: J3 cub, crash on take off nearly every time.
 


ORIGINAL: adamjedgar


Your mates problems with his cub probably relate to its construction and engine size than anything. I wouldnt dream of flying a 66" span cub on a 50 size nitro engine...it isnt powerful enough for this model. I had a 66" span cub with an asp 61 abc in it and the model flew like a dream, but i wouldnt have dared trying a smaller engine. My cub was only the second RC model aircraft i had even flown and not long after building it I lost an entire port side top wing skin and flew back and landed barely working up a sweat in the process (although i might have had a brown spot or two in my pants due to the shock of seeing that much covering material fall off an airplane all at once though:eek:).
Im sorry for the demise of that cub, its a real shame...but it happens!!!


so in other words you're burning holes in the sky with the cub, not flying it slow and scale like. flying it fast, it would be easy, its when you slow it down to scale speeds that it bites you. my cub when it was flyable would put around fine at about 40% throttle on a evo46nt and loop at about 80% and this is a 81inch cub. i have no idea why you would need a 61 for a 66 inch cub, looking for unlimited vertical or something or was the plane made of concrete?


my brother decided he wanted a cub also and bought a 40 size, yesterday he lost it when flying it for the second time. winds were howling at 15 mph with much stronger gusts, plane took off fine and climbed out fine into the wind, but he didnt realize what would happen when he would make the turn around and start flying WITH the wind. the plane dropped out of the sky like a rock in a flat spin right onto the runway.

Villa 01-20-2008 09:01 PM

RE: J3 cub, crash on take off nearly every time.
 
I fly my 71" inch wingspan cub, 7 LBS, with an OS 46FX and a 12X4 APC prop. Does great Hammerheads. Even knifeedges. A bigger engine is a waste of fuel.

adamjedgar 01-21-2008 04:02 AM

RE: J3 cub, crash on take off nearly every time.
 
You have hit the nail on the head my friends. You think a 70" cub will fly on a 40-46 size engine...yeah right...then you turn downwind and wonder why it fell out of the sky...the thing simply doesnt have any guts! Hammerhead a standard construction built 71" cub on a 46 eh...id like to see that. My cub was not a bullet, no cub is, but you expect that it will actually be able to reasonably maintain altitude (or relatively easily regain it) during most aerobatic manouvers. I hardly think the ones mentioned here would have any chance of that.

The simple fact is, aircraft often don't handle well when drastically underpowered. "Why?" Simply put, at low airspeed they are unstable due to higher angle of attack needed to maintain altitude (and as a result more drag), and the control surfaces are simply not effective enough at such low airspeeds.

In fact probably the one adverse thing that cubs are renowned for, and yes it does make them difficult at times to fly unless set up properly, is adverse yaw. This is common in higher wing aspect ratio aircraft, however, easily sorted via either mechanical or Radio means. I will say though, my cub had neither method and flew perfectly well.

Im not a veteran of RC flying, but i am no dummy either. i believe you should always aim to set up aircraft with above average power plants. For instance, a 66" cub is designed for 2 cycle engines sizes between .46 and .61. If you plan on simply flying straight and level mostly and not doing aerobatics the 46 will get your plane off the ground. However, should something go wrong and more power be required, the plane is history with this size engine. It will be running at almost 2/3 to 3/4 throttle just to keep the model in the air flying straight and level. Far better off with the .61. I could fly my .61 powered cub around at a genuine 1/2-2/3 throttle and happily fly at scale speeds. In fact its quite easy to solve the scale speed problem...change to a slightly finer pitch prop with a larger diameter the maintain correct thrust ratio. For those who really understand aerodynamics, aircraft speed is not absolutely determined by engine size. Its the propellor pitch combined with rpm that determines airspeed (obviously drag must also be factored into the equation). By increasing propellor diameter the expected rpm increase because of finer pitch is sorted.

I also, do not agree with the idea of building RC aircraft as light as you possibly can. Extremely light aircraft are touchy, require very rapid correction times, tend to be excessively floaty on flare, and susceptable to moving off course and glide angle on approach (just to name a few of the problems i can think of). Of course the one good thing about light aircraft is the lack of momentum created when approaching at step angles, but aircraft design is almost always compromise.

My cub was not in anyway heavy, she was standard kit built...plywood fues covered with solar film, and balsa wing also covered with iron on covering. The main reason for being in favour of heavier aircraft is, lighter aircraft don't handle wind well. If you dont agree, go watch a decent pattern ship flying through the rougher air and then compare its stability with your featherweight trainer and underpowered cubs (i know which aircraft i would rather fly). You might say its just because the pattern ship has a symmetrical wing and flys faster so the wind doesnt affect it as much....not that simple. It flys faster and, more importantly, is less affected by wind mainly because of higher wing loading (and obviously more thrust , however my thought here is about stability not speed). Higher wing loading in kit designed cubs is usually achieved by clipping the wings a little (of course it also noticably increases roll rate and thats another reason to do it)

I would recommend, any of you who doubt that cubs are good models to fly, ask an Aussie contacts to get you the Cub article in this months Australian RCM magazine. The article talks about a 2.3 metre wing cub project, and will surely put to rest some of this crap im reading about them here.

Happy flying


Yaniel 01-21-2008 07:53 AM

RE: J3 cub, crash on take off nearly every time.
 


ORIGINAL: adamjedgar

You have hit the nail on the head my friends. You think a 70" cub will fly on a 40-46 size engine...yeah right...then you turn downwind and wonder why it fell out of the sky...the thing simply doesnt have any guts! Hammerhead a standard construction built 71" cub on a 46 eh...id like to see that. My cub was not a bullet, no cub is, but you expect that it will actually be able to reasonably maintain altitude (or relatively easily regain it) during most aerobatic manouvers. I hardly think the ones mentioned here would have any chance of that.

The simple fact is, aircraft often don't handle well when drastically underpowered. "Why?" Simply put, at low airspeed they are unstable due to higher angle of attack needed to maintain altitude (and as a result more drag), and the control surfaces are simply not effective enough at such low airspeeds.

In fact probably the one adverse thing that cubs are renowned for, and yes it does make them difficult at times to fly unless set up properly, is adverse yaw. This is common in higher wing aspect ratio aircraft, however, easily sorted via either mechanical or Radio means. I will say though, my cub had neither method and flew perfectly well.

Im not a veteran of RC flying, but i am no dummy either. i believe you should always aim to set up aircraft with above average power plants. For instance, a 66" cub is designed for 2 cycle engines sizes between .46 and .61. If you plan on simply flying straight and level mostly and not doing aerobatics the 46 will get your plane off the ground. However, should something go wrong and more power be required, the plane is history with this size engine. It will be running at almost 2/3 to 3/4 throttle just to keep the model in the air flying straight and level. Far better off with the .61. I could fly my .61 powered cub around at a genuine 1/2-2/3 throttle and happily fly at scale speeds. In fact its quite easy to solve the scale speed problem...change to a slightly finer pitch prop with a larger diameter the maintain correct thrust ratio. For those who really understand aerodynamics, aircraft speed is not absolutely determined by engine size. Its the propellor pitch combined with rpm that determines airspeed (obviously drag must also be factored into the equation). By increasing propellor diameter the expected rpm increase because of finer pitch is sorted.

I also, do not agree with the idea of building RC aircraft as light as you possibly can. Extremely light aircraft are touchy, require very rapid correction times, tend to be excessively floaty on flare, and susceptable to moving off course and glide angle on approach (just to name a few of the problems i can think of). Of course the one good thing about light aircraft is the lack of momentum created when approaching at step angles, but aircraft design is almost always compromise.

My cub was not in anyway heavy, she was standard kit built...plywood fues covered with solar film, and balsa wing also covered with iron on covering. The main reason for being in favour of heavier aircraft is, lighter aircraft don't handle wind well. If you dont agree, go watch a decent pattern ship flying through the rougher air and then compare its stability with your featherweight trainer and underpowered cubs (i know which aircraft i would rather fly). You might say its just because the pattern ship has a symmetrical wing and flys faster so the wind doesnt affect it as much....not that simple. It flys faster and, more importantly, is less affected by wind mainly because of higher wing loading (and obviously more thrust , however my thought here is about stability not speed). Higher wing loading in kit designed cubs is usually achieved by clipping the wings a little (of course it also noticably increases roll rate and thats another reason to do it)

I would recommend, any of you who doubt that cubs are good models to fly, ask an Aussie contacts to get you the Cub article in this months Australian RCM magazine. The article talks about a 2.3 metre wing cub project, and will surely put to rest some of this crap im reading about them here.

Happy flying


my brothers cub fell out of the sky because of a newbie mistake he had the throttle VERY low as he was flying into the wind and didnt accelerate before turning. my cub would take off and fly perfectly at under half throttle. i never once went full throttle on it, yet it would roll, loop, fly inverted etc. and this is an 81 inch cub on a 46 with a 10x6 prop. i can show you the thread and people have even smaller engines on it and it flies fine. this cub with a 61 would be ridiculous, it would leap off the ground in 5 feet and rocket straight up and i doubt anyone that buys a cub wants it to do that. a 60 inch cub could probably fly fine with a 20-30 size motor.

fozjared 01-21-2008 11:40 AM

RE: J3 cub, crash on take off nearly every time.
 
great planes recommends as low as a .40 on their 76.5" j-3 cub kit..

http://www3.towerhobbies.com/cgi-bin...&I=LXJ568&P=SM

i run mine with an evolution .46 and it is a little overpowered to fly scale.. flying the cub is actually fairly easy, what i meant to say was that it is a difficult plane to take-off and land, at least the first 10-12 times you take off.. once you get used to it, it is similar to a trainer, with a few odd characteristics.. if you had ever been in a real cub you would know that take-offs can be a bit unnerving the first time or two considering that you can't see until that tail comes up off the ground..and just because the tail pops up doesn't mean she's ready to fly, you have to use elevator management to allow it to build some airspeed too much elevator means a tip stall when it rises, too little and it can nose over, especially on a grass strip which is what i fly off of.. all of that elevator management kinda goes out the window when you overpower a cub, because when you shoot the throttle open and get rolling you can just yank it into the air and off she goes, but that is not what "scale" is all about now is it? i have a yak with an oversized engine and it will take off in a few feet in spite of its weight. but that is not a scale plane, it is a sport plane. if i wanted the cub to be a sport plane i would have bought something else. what i wanted was a scale replica of a j-3 cub with semi scale flight pattern, not a plane that leaps into the air and screams across the runway!! i get mine off the ground under full power, once it is at flying speed i rarely take it over 2/3 throttle, most of the flying is done at 1/3 throttle.. the cub's wing is made to have a lot of lift, not to be fast. it will carry a lot of weight and you won't really be able to tell the difference, even with an underpowered engine. 1:1 cubs, some have 65 hp engines, talk about underpowered (at least in your book) but there have been several of them flying around with floats on carrying people and camping equipment back into the mountains. flying a scale plane like these cub's, at scale speeds requires talent/skill there is no doubt about that. but taking a scale cub and ripping it through the air with an oversized engine takes little effort, and in that instance, i agree with your statement:

Cub hard to fly???? bull. That is an absolute load of crap!!!

The very design of this model makes it completely the opposite...

the very design of your overpowered model does make it quite opposite, take the .61 off of your plane, buy a os .40 la and put on it (it will fly great with the .40, trust me) fly it a couple times and then come back on here and tell us how easy cubs are to fly.. if you are successful (the reason i say if is because you are used to yanking it into the air i am sure, which is something you won't be able to do with the .40) tell us instead how you enjoy flying a scale plane, it is far more enjoyable than just racing across the sky in a plane that wasn't designed to do so!

Yaniel 01-21-2008 04:51 PM

RE: J3 cub, crash on take off nearly every time.
 


ORIGINAL: fozjared

great planes recommends as low as a .40 on their 76.5" j-3 cub kit..

http://www3.towerhobbies.com/cgi-bin...&I=LXJ568&P=SM

i run mine with an evolution .46 and it is a little overpowered to fly scale.. flying the cub is actually fairly easy, what i meant to say was that it is a difficult plane to take-off and land, at least the first 10-12 times you take off.. once you get used to it, it is similar to a trainer, with a few odd characteristics.. if you had ever been in a real cub you would know that take-offs can be a bit unnerving the first time or two considering that you can't see until that tail comes up off the ground..and just because the tail pops up doesn't mean she's ready to fly, you have to use elevator management to allow it to build some airspeed too much elevator means a tip stall when it rises, too little and it can nose over, especially on a grass strip which is what i fly off of.. all of that elevator management kinda goes out the window when you overpower a cub, because when you shoot the throttle open and get rolling you can just yank it into the air and off she goes, but that is not what "scale" is all about now is it? i have a yak with an oversized engine and it will take off in a few feet in spite of its weight. but that is not a scale plane, it is a sport plane. if i wanted the cub to be a sport plane i would have bought something else. what i wanted was a scale replica of a j-3 cub with semi scale flight pattern, not a plane that leaps into the air and screams across the runway!! i get mine off the ground under full power, once it is at flying speed i rarely take it over 2/3 throttle, most of the flying is done at 1/3 throttle.. the cub's wing is made to have a lot of lift, not to be fast. it will carry a lot of weight and you won't really be able to tell the difference, even with an underpowered engine. 1:1 cubs, some have 65 hp engines, talk about underpowered (at least in your book) but there have been several of them flying around with floats on carrying people and camping equipment back into the mountains. flying a scale plane like these cub's, at scale speeds requires talent/skill there is no doubt about that. but taking a scale cub and ripping it through the air with an oversized engine takes little effort, and in that instance, i agree with your statement:

Cub hard to fly???? bull. That is an absolute load of crap!!!

The very design of this model makes it completely the opposite...

the very design of your overpowered model does make it quite opposite, take the .61 off of your plane, buy a os .40 la and put on it (it will fly great with the .40, trust me) fly it a couple times and then come back on here and tell us how easy cubs are to fly.. if you are successful (the reason i say if is because you are used to yanking it into the air i am sure, which is something you won't be able to do with the .40) tell us instead how you enjoy flying a scale plane, it is far more enjoyable than just racing across the sky in a plane that wasn't designed to do so!

bravo bravo!

my biggest problem with the cub was letting it build enough speed for take off. i was used to full throttle and pulling back and my planes shooting vertical. thats not what scale flight is about and it took me some getting used to. but the evolution 46nt still over powered OVERPOWER the 81inch cub in my opinion. if and when i rebuild my cub, i'll probably be using a 36 in it.

fozjared 01-22-2008 12:05 AM

RE: J3 cub, crash on take off nearly every time.
 
i have heard lots of people recommend a .61 with the clipped wing version if i want it to perform aerobatically, this thing performs so well with the .46 i wouldn't dream of putting a .61 on it! i would actually prefer the full wing version of this cub, but i got such a super deal on this plane that i couldn't pass it up, it was built by an elderly gentleman that has amazing building abilities, this is a well put together plane and i don't think i could be more pleased, not only with it's looks, but with it's flight characteristics as well.

NorfolkSouthern 01-22-2008 06:47 AM

RE: J3 cub, crash on take off nearly every time.
 
I have a few questions, they are Cub related. I would like to ask if anybody here has had any experience with other high wings. Namely, Cessnas, Decathlons, and Citabrias. How do those three compare to the Cub? I think a Cessna is only slightly less controversial than the Cub, and I have heard people tell me that Decathlons and Citabrias are not very good in smaller sizes. Do any of the three planes mentioned have better flight characteristics than the subject of this discussion? Is one of them more "forgiving" than the others? Or, are they all similar?

NorfolkSouthern

Villa 01-22-2008 10:46 AM

RE: J3 cub, crash on take off nearly every time.
 
Hi adamjedgar
You certainly have strong opinions about a more powerfull engine on a 71" wing span cub. I have had 2 Sig Kit 71" J3-Cubs and they flew great on a 40 size engine. My kit built planes are always on the heavy side since I reinforce them a great deal. A Hammerhead stall is part of my standard manuevers and I'm certain I had no problem doing them. This was in the early 1980s. About ten years ago I gave away my two 61 engines after I noticed that the fuel usage was twice what my 46 engine did. I have been flying RC since 1972 and now have limited room for my planes. My current 71" WS J3-Cub is a SPAD plane I designed and built from COROPLAST corrugated plastic sign material. At 7 LBS I thought it was very heavy but later I checked the specs an similar cubs and found mine was not bad at all. I have mine built like a tank. I had three bad crashes during takeoff (I had forgotten all I knew about a Cub on takeoff) and the damage was hardy visible though I sheared off a bunch of 1/4-20 nylon bolts on the wing and landing gear. I have never felt it was underpowered, but oviously that is a personal thing. It certainly does not have unlimited vertical performance but I have never felt that was a requirment for a hammerhead stall. I have other planes if I want to do wilder manuevers. My current Cub, named COROCUB can be seen here at:
http://www.rcuniverse.com/forum/m_44...tm.htm#4433841
I love flying in high winds, but not with the cub. It gets blown over on the ground very easily and it windvanes into the wind on takeoff. I have better planes for high, gusty winds. Turning into the wind when flying slow with a cub is no problem if you know what is going to happen and take the proper action, preferably before it is needed.


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