p-47 razorback pilot

My Feedback: (5)

first, anyone use a o.s. 320 quad 4 in a j3 cub? was told this engine looks most scale in the 1/4 scale j3 rather than the 1/3 thoghts????


2nd, who has the more scale 1/4 j3 cub kit? balsa usa or sig? thanks guys

Wayne22

My Feedback: (2)

Half of that would be more than enough..I've seen them used on 1/3 scale cubs......now having said that, I have a G-38 stuffed in mine.

As far as scale goes, I have one of each. Neither are that close to scale and there are surprising differences between the two. With work, either kit can be bashed to be much closer to scale....

Here are a couple of examples that I have seen in my travels...


This one is a clipped wing Sig built by a friend of mine (OS 120 single)



And this one is a Balsa USA kit (OS 160 twin)

Magnus76

Hello P-47

My friend was test flying his new built j3-cub in this weekend. He has a OS .91 in his 1/4 scale and his modell is flying very good.

RCPilot100

My Feedback: (4)

Would be waaaaay too much - nice in a 1/3 scale - but not a 1/4 scale. My good buddy flew one for about 10 years and is building a new one. I am too.

Dan

p-47 razorback pilot

My Feedback: (5)

yeah dan i knew thart i was hoping the engine heads would look more scale in the 1/4 verse the 1/3 in the 1/3 they look alittle small i can cut wayyyy back on the throttle going for a scale 4 head look thoughts on this?

bla bla

It's an idea.
The positive thing is you live in an area where you'll have no problem picking up a dead horse to use as tail weight.
Don't bother. To big, to heavy to much power and thats not condusive to happy Cub flying and if that isn't enough, think of all those glow plugs. Yikes.
Still not convinced, contact the local stables.

Wayne22

My Feedback: (2)

...so let me get this straight.....you want to put an expensive, heavy, overpowered engine in a quarter scale cub just so you can look at the cylinder heads????!!!!!!!!!


.jes kidding...why not use a gemini twin and add two OS cylinder heads on behind (one on each side, of course) The cub on floats up above has the rear cyclinders cast from resin, and unfortunately, it does show (on an otherwise gorgeous cub)...why not use the real thing?

Wayne22

My Feedback: (2)

One more thing to consider is that the bigger engine requires a bigger prop (18-8 to 22-6 they are calling for..) and at idle it will be pushing back a considerable amount of air (thrust). Even though a cub has a lot of built in drag, when it gets into ground effect with those long wings it does not want to stop flying. This I speak with considerable experience..... This is not a show stopper, but something to consider when planning your landings...

p-47 razorback pilot

My Feedback: (5)

?????? never thought of using the o.s. 160 twin and adding 2 more cylinder heads to make it look like a 320, where would i get these?

BobH

My Feedback: (2)

I watched a friend fly his 1/4 cub this past weekend with the OS 320 4 cylinder. I asked him about it and he said the engine worked ok in the plane and typically he flew it a little under 1/2 throttle. But there were no "issues" related to the engine. His looked, sounded and flew very well.

p-47 razorback pilot

My Feedback: (5)

mr. bob,

any chance you might be able to post some pics of it here? did the heads on the 320 look more scale hanging out of the cowl on the 1/4? they look alittle small in the 1/3 scale thanks sooo much

BobH

My Feedback: (2)

Sorry but I didn't get any pictures of his cowl. I do know that he trimmed the cowl a bit such that the cylinder actually stuck out a bit more than on the Prototype. I asked him about his engine with your original post in mind. He had no muffles only the straight pipes for the exhausts.
As you know the Cub has a shield that partially covers the inside portion of the cylinders. His cub did not have the shield on each side.

HHjul

I think there should be no problems using FF-320 in 1/4 Cub. Anyway, there is some issues you should take care of. This is "The European Way" to make things work...

1. Build your plane as light as possible... especially the front end has to be VERY light!
2. Install tail servos as far back as possible
3. Install all radio gear as far back as possible

Then, you should use an ultra-low pitch prop in your Cub, for example 20x4... (Where to get one... don´t ask!) Adjust the engine and the throttle movement so that you limit the maximum rpm at full throttle to 7000-7500 rpm. Always use on-boarg glow system to ensure reliable low idle.

By doing this way, you can keep the total flying weight down and you don´t have to balance your Cub by using any extra ballast. Or only a very small amount.

This is the formula I will use when using a Saito FA-325 radial in my 1/5 Gloster Gladiator...

Regards, Hannu

RCPilot100

My Feedback: (4)

Bob,

Gotta ask - are you building a super scale Cub for looks or a somewhat scale Cub to fly. Myself, I prefer something that is somewhat scale that I can fly the snot out of. Like I said, my buddy and I are building 1/3 scale Cubs now - his previous one had the OS 320 in it which was really nice - we are now going to power them with DA 50s - dummy cylinders on the side - just enough to look good in the air. Most anything looks good in the air. He flew his previous one so much he had to buy a second backup OS 320 - and glow fuel by the case load.

If I was gonna do a 1/4 scale Cub, I would look at one of RCIGNs G26s with dummy cylinders on the side - again so I could fly the snot out of it. A bit cooler engine would be the OS 160 twin - and I would only have the two cylinders sticking out. I had a friend that had this exact combination and he flew the snot out of it.

I have a friend that has a Super Cub - full scale - and from what I have learned from him is that there is nothing standard with any of them. He has made many mods and that is the way the plane is. You could not model a standard Super Cub and say it was a model of his - not only he but previous owners have modified it and it is what it is. Right now it is for sale - the next owner will undoubtedly make mods himself.

Dan

FlyingTyger

My Feedback: (2)

The 320 is way too much engine. I had a Balsa USA 1/4 scale L-4, fully detailed with an O.S. 91 Surpass spinning a 16X6 prop. It weighed 14 pounds. It took off very scale-like at about 1/3 to 1/2 throtle. Most of the flying I did was at less than 1/4 throtle. If I had the idle set a little high on landing, it was hard to get it to stop flying and usually resulted in a bouncy landing. At full throtle it cruised around at about 60 mph. I could do as many consecutive loops from level flight as I wanted, with no lose of altitude. In general, it didn't fly very good fast. A Cub is designed to be slow and gentle , and as stated before has a lot of drag. When forced to fly that fast, mine seemed to seek or hunt for a heading.
Good luck with your project, but I would have to recomend the 160 twin, nothing bigger.

BobH

My Feedback: (2)

Dan, I'm not building a cub.. that is the other gentleman. I was just commenting on how I witnissed a cub flying this past weekend with the OS 320. Lots more engine that it needs but there is always the left stick on the Tx to compensate for that..

p-47 razorback pilot

My Feedback: (5)

guys, i totally get that its way too much engine, as bob said i can fly it with 1/8 1/4 stick, i just tought the 1/4 scale j3 would look more scale with the 4 cylinder heads of the 320 hanging out the cowl than the 1/3 scale did i think it looks too small in the 1/3 thoughts bob? how scale did the 320 look in the 1/4 j3?

Boomerang1

Must ask the question, do you actually own a 320? If I did own one & wanted to make a 1/4 scale Cub I would make it fit & fly the thing at reduced throttle. If I had to purchase an engine to suit a 1/4 scale Cub I would buy the 160 & dummy up the rear cylinders. Or a 120 single inverted & dummy up the 4 cylinders.

How would the 320 look in a 1/3 scale Cub? I think NONY has answered that already. As you can see the 160 (really the 2 front cylinders of the 320) looks the correct size in a 1/4 scale Cub. Of course it will look too small in the 1/3 Cub. - John.

BobH

My Feedback: (2)

The engine looks just fine in a 1/4 scale cub. It's about the right scale size. It's too small for the 1/3 cub for sure.

liv4bk

Hey guys I'm looking to build a 1/4 cub. Looking at the Sig. I want to put a Saito 270 twin on it. What are your thoughts?

Wayne22

My Feedback: (2)

A sig 1/4 cub will fly with a Saito 91, although a 120 is most commonly used..using that as a reference, you can weigh the advantages and disadvantages of the bigger powerplant.........

liv4bk

thanks alot for your response. I'm new at this. I've been flying 40 scale planes and am ready to go larger. I have a Saito 270 twin and was looking for a plane to put it on. I thought the cub would be the one because it would kinda match the engine looks. Obviously this is way too much engine for that 1/4 scale. I see there are a couple of bi planes that take the larger engines. The Pitts 2.2-2.8 looks like it would be ok for my engine. I don't want to over power-over weight the plane. I want a plane that will land without power. The saito 270 weighs about 4 pounds so I need a plane that will hold it up till I can glide it to a soft landing if the engine dies in mid air. I practice this all the time with my 40 scales but they are cheap enough to take a chance. I've tried just about every failure configuration I can think of and have been able to put them down in one piece all summer. Any and all your giant scale suggestions would be greatly appreciated.

mr2mk1

Don`t you Americans think about weight in your planes ? A 320 pegasus is a very heavy engine ! To balance a 1\4 scale cub with that big engine you would have to ad a lot of weight in the tail . I have a 1\4 scale h-9 super cub with a laser 100 sounds grate and its plenty of power to spear !

706jim

Old thread but Google found it. My Sig 1/4 Cub is powered with the OS FF240 probably the same size and weight as the FF320. Flies great and at part throttle sounds very realisitc. No extra need for tail weight, I just moved the flight battery a bit behind the wing trailing edge to achieve balance. And I did not cover up the cylinders with the scale baffles. Why spend that much on an engine and hide it?