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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)

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.

waydown2low 01-22-2008 12:47 PM

RE: J3 cub, crash on take off nearly every time.
 
Ok guys, enough about the engines, it doesn't matter. A plane is only as good as the guy flying it, it doesn't matter if it has a os 40LA or a Saito 82. I flew a Goldberg cub with a O.S. 70 fourstroke and it was a sweetheart, have also flow the same plane with a os 40 fp. Take off roll was only about five feet longer on the forty. More power is great, but not required but will often get you out of a bind when the smaller one won't. The only problem is that when tthe plane gets in a situation that requires more power, they are already over controling the plane and a crash is immenent, no matter what is roaring up front.

I have seen very experienced flyers do the cub snap and eat dirt, it happens! It is up to the builder to decide what he wants up front and what he can afford and so on. In the words of great pilot, fly what ya brung! I won't discourage starting with the cub, I have tought several to fly with cubs and eventually every one of them did the snap but they are all really good pilots now and would probably owe alot to it learning with the cubs. They were Goldberg and Greatplanes kits, nobody had seen many arfs other than trainers and Laneir arfs. Ahh the good old days!! I still am not sold on these cheap china models yet, have not seen one yet I liked but hey, that is another can of worms!

fozjared 01-22-2008 02:06 PM

RE: J3 cub, crash on take off nearly every time.
 
i have had a few of the china model arfs, most lacking hardware, instructions and some of the hardware that wasn't missing was inferior hardware.. but i do have one china model that i was and am extremely pleased with, in case you are interested here it is:

http://texasrcplanes.com/arfyak543dblue.html

the guy that owns texasrcplanes.com is a super guy and has the best customer service, you can call him up and talk to him anytime, but be prepared to get an earful that man can talk all day long about planes! he sells only the china model planes, but with minor experience you can improvise with the instructions what goes next in the final assembly, add a couple of pieces of your own hardware and you will have a super plane! plus he has the cheapest planes i have ever found..

phippsa3 01-25-2008 12:18 PM

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.


Just to let you know that i fly my 1/4 scale cub 108" on a saito 91 and thats plenty of power.
Flys very scale at way less than 1/2 throttle.

If you enjoy scale flight then there is really no need to overpower.
70" cub will fly very nicely on a good 46 2st.

phippsa3 01-25-2008 12:29 PM

RE: J3 cub, crash on take off nearly every time.
 
1 Attachment(s)
And here is the old girl!

JPANN 01-25-2008 01:21 PM

RE: J3 cub, crash on take off nearly every time.
 
That's a nice one phippsa3, I like it alot. It looks just like mine only 20" longer wing. ARF or kit?

waydown2low 01-25-2008 05:10 PM

RE: J3 cub, crash on take off nearly every time.
 
Just out of curiosity, what is the price difference for a plane in London compared to the states? I have always wondered if things were about the same after money value change.

NorfolkSouthern 01-27-2008 07:36 AM

RE: J3 cub, crash on take off nearly every time.
 
OK, dumb question again. For those who have several high-wing planes under their belt: How easy is the Cub to fly, compared to others like the Dakathlon, Citabria, or Taylor Craft? Sorry, didn't mean to interrup but I am burning with curiosity....

NorfolkSouthern

waydown2low: It fluctuates, but I can most certainly say that it will cost more in Europe with converted U.S. dollars. This is, of course, due to the exchange rate and the dollar has been losing more value with lower interest rates.

Villa 01-27-2008 09:08 AM

RE: J3 cub, crash on take off nearly every time.
 
Hi NorfolkSouthern
I have had three of the 71" WS J3-Cubs. I have been told by other experience R/C pilots that the other three planes you mentioned are easier to fly. I have seen them fly and they do not seem to be as difficult as my cubs.

NorfolkSouthern 01-27-2008 05:16 PM

RE: J3 cub, crash on take off nearly every time.
 
Thanks for the help, Villa. I've seen quite a few Citabrias and Cubs. The Cubs are flown more conservatively, while Citabrias seem more aggressive. This is probably due to easier stall recovery and the use of more engine power. I think part of the trouble with Cubs would be the barn door ailerons and flat bottom wing with a thinner airfoil. Would that be a correct observation? How would a Cub compare to, say, a Cessna?

NorfolkSouthern

Villa 01-27-2008 06:59 PM

RE: J3 cub, crash on take off nearly every time.
 
The Cessna models I have seen (46 size and larger) seem to fly very well. I think a main difference is that the Cub wing is longer than it needs to be. The clipped wing Cubs seem to be OK. I don't think I would like my Cub as much if it was easy to fly. I like the challenge; the difference. I have learned that if I have not flown my Cub in a while I better do a lot of thinking, remembering, and be super alert on the first takeoff/landing.

Live Wire 01-27-2008 07:51 PM

RE: J3 cub, crash on take off nearly every time.
 
Norfolksouthern.
I have three J-3s, and it depends on how they are built how they fly ;) You build them to exact scale and they fly scale, You change the landing gear CG , motor offset and a few other thing and you have a trainer. But I like scale and you have to learn to fly them.

fozjared 01-27-2008 11:49 PM

RE: J3 cub, crash on take off nearly every time.
 
villa, i am the same way, if it has been more than a week or so even, i have to stop and think about what goes into getting her off the ground and then back down safely! its not incredibly difficult, but i do have to stop and change the way i fly my other airplanes, it's like i have to change channels in my mind. i love the different way my cub flies, it is totally different and it seems new to me each time i go for a spell without flying it!

bassfisher 01-28-2008 11:48 AM

RE: J3 cub, crash on take off nearly every time.
 
I've flown multiple size cubs (both Full Size and models) over the years - this weekend I test flew at 96" Cub for a fellow club member that he got for a song and a dance - wish I had known about it, I would have bought it.. The plane had a 90 4S on the front that had not been run in a few years. Once we got it started and running well, up I went. As I taxing out, he was worried that I would ground loop it - I told him right before I started the take-off that the Cub likes rudder and to get the tail flying before trying to break ground. Take-off, stayed on the rudder, got tail flying, and it just rose right off the runway. Just flew around at 1/4 throttle until I ran out of fuel. Dead stick landing, no problem- what a floater. Just remember that the bigger the Cub, the more you have to be on rudder.

timothy thompson 01-28-2008 08:45 PM

RE: J3 cub, crash on take off nearly every time.
 
cubs are not trainers you need experience with flying. going from small e power to large glow is difficult at best

Yaniel 02-03-2008 07:04 PM

RE: J3 cub, crash on take off nearly every time.
 
finally had a successful day of cub flying! i took my buddy out to maiden his h9 pnp cub 40, he'd never flown glow nor a cub before so he asked me to maiden it for him. i was a little scared but i had a lot more experience flying glow planes than i did when i crashed my own cub. I dailed in a bunch of expo on the rudder and it really helped the ground handling the plane would almost track perfectly down the run way, gave it more run way that it probably needed and it climbed out beautifully. only problem i noticed was that since the winds were blowing at about 15 mph when i would start turning it would try to blow the wing over so it needed a lot of aileron work to keep it from stalling out on a turn. now i'm going to rebuild my cub because the plane is a joy to fly once you figure out its quirks. with a 4 stroke though because i didnt realize how awful a cub sounds with a 2 stroke when i had mine!

ltriska 02-03-2008 09:18 PM

RE: J3 cub, crash on take off nearly every time.
 
either i missed it, or no one mentioned after all the crashes, the receiver might be crapped out, especilly if it's a futaba.:eek:

Villa 02-05-2008 10:34 PM

RE: J3 cub, crash on take off nearly every time.
 
Hi ltriska
I have had about 12 receivers, the majority Futaba. In well over 100 crashes since 1972 I have never damaged one receiver. I have ripped more than one antena wire, but I soldered them together. Are yours well protected? What kind of problems have you had? I do recall now replacing one or two crystals on the receivers after a severe crash. Do you count those?

Yaniel 02-06-2008 08:19 AM

RE: J3 cub, crash on take off nearly every time.
 
i did it... i placed the order at the lhs for a new fuse, cowl and and windshield along with a saito 72! i cant wait to go cubbing again!

ZX11 02-12-2008 08:56 AM

RE: J3 cub, crash on take off nearly every time.
 
Interesting how difficult some cubs are. My second plane was an eflite 25 cub. It was my first big plane at 60" wingspan:D That cub has never given me any trouble and flys great. Everything I hoped for flying a cub. Slow flights, gentle moves, flat turns, and great looks. Ground handling is fine if I stay on the rudder early. But I fly off of grass and have heard it is easier. I take off on low rates and then switch to high rates for loops and rolls. Two important parts of my set up is differential ailerons and balancing it so the wing is level instead of the fuselage. The fuselage can throw you off.

eniac 02-12-2008 06:15 PM

RE: J3 cub, crash on take off nearly every time.
 
I built an Adrian Page 40 inch Super Cub a couple years ago, and was very appreciative of how much ground handling challenge it provided. I was able to get very close to the rudder in terms of my flying style, and have since applied the lessons learned to other airplanes. The biggest thing really is that whole 'get on the rudder early'.

I still fly it rather often, and the Super Cub has racked up more than 40 air-hours - really a gem - even with a weak (scale!) gws 350 motor.

People in the know really take a second look when you are able to takeoff and land a comparatively small cub, in a near-flight-speed crosswind and not ground loop, or veer off during the whole cycle. Helps keeping your other planes in good shape too!

eniac

Yaniel 02-12-2008 10:21 PM

RE: J3 cub, crash on take off nearly every time.
 
i've been flying my friends h9 cub40 while i put mine together, i think i'm definitely ready to get my cub in the air again! I've been able to put the cub on the center line of the run way and keep it there til the mains lift off the ground at a very scale like speed and with a STRONG crosswind. Meanwhile my cub should be done tomorrow, went with a saito 72 instead of the evolution 46 2 stroke this time around, i cant wait to fire it up!

JPANN 02-14-2008 01:45 PM

RE: J3 cub, crash on take off nearly every time.
 
Good for you Yaniel, keep us posted on your progress.

Yaniel 02-18-2008 08:55 PM

RE: J3 cub, crash on take off nearly every time.
 
I finally re-maidened my cub, had about 5 flights, 0 problems. take offs were easy now, i guess i'm more comfortable with the plane. landings where very difficult because of the 12 mph cross wind. the saito 72 flies it around with only a couple of clicks of throttle. one time just for fun, i jabbed the throttle to full while on the ground and the plane was off the ground in about 5 feet.

layback2 02-27-2008 09:45 AM

RE: J3 cub, crash on take off nearly every time.
 
So JPANN
What happend did i miss what happend with your friends new plane last i read you said it was all most finished and ready to fly like most post get caught up in talk and loose why i was reading in the first place the cubs what happend

JPANN 02-27-2008 10:11 AM

RE: J3 cub, crash on take off nearly every time.
 
Layback2,
You are correct, this post took on a life of it's own but that's cool.

The first cub was a Nitro model plane and I killed it during that crash so that particular plane never flew again. The second cub was a Richmodel and he did infact have a successful maiden flight. I did not get to see this with my own eyes but the palne is still in perfect condition, there were plenty of other witnesses that corroborated his story! :) Unfortunatly (because we live in Michigan) the weather is not the greatest to fly in now so neither of us have done much flying much to our disappointment.

I have come to the conclusion that the first cub did not fly because of design flaws. The second cub was not built (by us) any diffrently then the first and it flew flawlessly. I have a cub just like the second one I have mentioned and have never had a problem flying it, I have had landing gear issues however. We took what we learned from my cub and applied it to his. We actualy fabricated our own landing gear and it works great. My friend is real good at that crap because that is what he does in the real world. He has made landing gear, special exhaust systems, and many other minor fabrications that work well.

I did find it interesting that some of the posts on the second or third page alluded to the cub being somewhat difficult to fly if you are going for "scale". If that be the case, maybe the first cub actualy flew fine and the pilot was the problem??????

layback2 02-27-2008 09:17 PM

RE: J3 cub, crash on take off nearly every time.
 
wow cool to hear i have a smaller cub wing span 50inches and 31 inch fuse that i have problems understanding the )_(_&^%^%^$$##$ manual its in a langlish no one can understand i have it build but the cg and the rons and rudder and elevator is not right the airons say 1.1 up and 1 mm down funny and the rudder says 30 to the right and 36mm to the left what a mess and the elevator say 36mm both ways they cant be right oh the cg is really not that bad 56 to 66 mm how can i set the thows i need to read more and ask for help darn model is a CY model sold by texasrcmodels they cant even help i email them 4 times and got no help at all

JPANN 02-28-2008 03:33 PM

RE: J3 cub, crash on take off nearly every time.
 
this may take a few mins to reply as I am laughing at this: "i have problems understanding the )_(_&^%^%^$$##$ manual its in a langlish no one can understand". I feel your pain!! Langlish:) I have my rons at about 3/8" both ways keep them even. The rudder has by far the most travel at about 1/2" both ways, keep them even. The elevator is at about 7/16", both ways keep them even.

Others may tell you diff, that is just the way I did it. Every palne may be a little diff. Keep in mind that my cub has a 71" wingspan and is 42" long. Theese are what I think are high rate settings, you should use dual rates (if you have the radio that will do this) and start with the shorter throws.

PS,
" means inches.

JPANN 02-28-2008 03:41 PM

RE: J3 cub, crash on take off nearly every time.
 
Oh,
The cg you mentioned sound about right too. Mine was 67mm.

jaybird11 02-29-2008 02:23 AM

RE: J3 cub, crash on take off nearly every time.
 
1 Attachment(s)
HELPPP I HAVE FORGOT THE NAME OF MY PLANE.LOL
Anyone know the name of this Goldberg cub??
It has a 76 inch wing span,I bought it about 9 months ago ,put a Saito 82 in it with smoke and hung it in the hanger,.
Now Im ready to fly it and cant find much info on it. I have never flown a cub and do know to use redder on take off as it rolls on two wheels when taking off.
It is s Goldberg _______ ? thanks and any info on set up thank you too.

jaybird11 02-29-2008 02:24 AM

RE: J3 cub, crash on take off nearly every time.
 
Sorry about the picture it shows the la 65 it had in it when I bought it.


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