bonanzadrv

My Feedback: (21)

I have one of these going on a balsa usa 1/3 scale j-3 cub. Just wondering how these things run. I have heard so much about how great thet sound, but do they run?? Is it true it takes alot of work to keep them running. Anyone know how well it will fly a 1/3 scale cub. Any other tips or suggestions would be great.

Thanks
Bill

iflyj3

My Feedback: (7)

I have one in a 1/3 Pitts. It is a wonderful engine. Mine turns a 22x8 at 6400 RPM. It will idles as low as 720 RPM although I actually idle it at about 1000 RPM. As far as power, a colleague has a 300 twin in his and it is more powerful but doesn't have that sound like the four cylinder. It flys my Pitts fine with big round loops and all. Your Cub will be great with this engine and like mine everyone wants to just hear it idle. I set the needle valves once and have not had to touch them since.

I used the choke on the engine for starting. It starts easily by hand and you don't even need a chicken stick. I have yet to use a starter. I have onboard glow that works with throttle position or I can turn it on or off via radio. I use it to start the engine and switch it completely off as I have yet to have a cylinder flame out even at 720 RPM.

The exhaust are 3/8 inch chrome plated fauct supply tubes from the local home supply store, cut to fit. I put a pressure tap in one of them. Even with the straight exhaust the engine is unbelievably quite.

On fuel comsumption. I oversized my fuel tanks due to experience with the big Saitos. However, I flew a 10 minute full throttle flight with one takeoff and landing during the flight and it burned 12 ounces. I had put in a 24 and a 16 ounce tanks for a total of 40 ounces, I thought I would need. I have since disconnected the 16 ounce tank.

Fly the plane with the engine at 2K to 3K, which the Cub should do, and it will sound just like the Continental from which it was copied. Normal cruise for a 65 HP Cub is around 2150 depending on the prop.

Hope this helps.

donkey doctor

Hello; I have one of those wonderful engines, I bought it to go into my Piloot 1/3 scale cub. The engine is so beautiful I bought a Quadra for the cub instead. I also had it in a Byron 1/3 pitts for awhile until I sold the plane. I run it a few times a year, it's just a wonderful engine, quiet smooth and powerful. I built a bench mount for it so I can bring it out and fire it up in just a few minutes. I also have an on-board starter for it, but the batteries to run it are so heavy, I never used it in a plane.

Also a friend of mine has one in a 1/3 scale cub. He paid $300 just for a scale exhaust manifold, stainless of course. That engine flies the cub very well, with a huge reserve of power if you need it. Trouble free, Brian flies teh cub quite often, but he hates cleaning up afterwards. That engine will power your cub easily and will draw a lot of attention every time you fire it up. I use a 20 x 10 on my engine which turns it at 8800 rpm. It will idle down below 1000 rpm. without glow.

RSL_Mongoose

What onboard glow are you using?

Kmot

My Feedback: (24)

Guys, will one of you PLEASE make a one minute video of your engine running, idling, etc? Pretty please?

iflyj3

My Feedback: (7)

If this message is directed to me, I design, program and build my own on board glow devices.

iflyj3

My Feedback: (7)

I would but I don't have digital video. To simulate the FF-320 idle, turn your PC sound completely off and watch the prop turn. That is about how quite it is with straight pipes.

RSL_Mongoose

I'm planning on a Pitts in the next month or so, just trying to get all the info I can on the engine.

iflyj3

My Feedback: (7)

Great engine but not a power house. But the sound and idle make up for a lot.

RSL_Mongoose

Is there any major mods that have to be done to fit the engine in the GP Pitts?

iflyj3

My Feedback: (7)

I had to move the firewall back .75 inches IIRC. I kept the same right thrust and made a jig to make sure I got the firewall back in at the correct angle. Other than that it was no different than any other installation. Oh, moved the tank to the bottom since that is where the carb is located.

Kmot

My Feedback: (24)

I'm confused. [sm=spinnyeyes.gif]

iflyj3

My Feedback: (7)

About what?

iflyj3

My Feedback: (7)

For what it is worth, here is a writeup I did a while back. Hope it helps.
-----------------------------------------------------------------------------------
GP 1/3 Pitts and OS Pegasus FF-320 4 cylinder

After reading a review in Model Airplane News about the Great Planes 1/3 scale Pitts my
interest was tweaked, especially about using standard servos. Then I read somewhere about a FF-320 being installed in the 1/3 Pitts. Both of these things caused me to purchase the Pitts as I had already owned the FF-320 for about 7 years. The 1/3 scale Space Walker kit that I had bought for the FF-320 was still in the box and no immediate hope that it would be built.

I have finally finished the GP 1/3 Pitts ARF with the OS Pegasus FF-320 4 cylinder
engine and this will be a report of what I did.

The first problem I encountered was there where no holes marked on the lower wing for
the I struts. After several emails and two phone calls I was able to get the dimensions from GP.

The engine installation required the firewall to be moved back 3/4 of an inch. This was
done by carefully cutting out the old firewall and making a new one from two pieces of 1/4 inch aircraft plywood glued together to form a 1/2 inch thick firewall. This firewall was dowel pinned to the original box using bamboo. To maintain alignment of the built in right thrust I made a jig from 1/4 inch all thread rod and a plywood ring to center the prop hole in the cowling.

Since I was usin a 3.2 cubic inch glow engine I figured that it would use about 3 ounces of fuel per minute. The 24 ounce tank supplied would only last about 8 minutes. I decided to install two tanks. Since the carburator is on the bottom of the FF-320 the fuel tanks had to be moved down to the bottom of the fuselage. Two of the 24 ounce tanks would fit side by side. I contacted GP by email and phone calls several times over the course of 6 months and the tank they send with the plane is not available separate. I finally used a 16 oz. tank as the second one.

The MAN article said that standard servos were used. However, in the next issue that was corrected by the author and he listed the actual servos that were used. After analyzing the ones he used I determined that standard servos should work. Where he used one servo on two ailerons I chose to use one servo on each aileron. This means that two 44 in oz. servos will do the work of one 88 in oz. servo. I used four Futaba 3004 servos on the ailerons and two on the elevator. I did use a Hitec 605 on the rudder as it also takes the beating from the tail wheel. For the throttle a Hitec 81 was used. Before you say these servos won't work keep in mind this is not a 3D machine. It rolls, loops, spins and snaps well.

I built my own on board glow driver that has two isolated circuits that controls two plugs
each in series. This glow driver allows control via throttle position or can be turned completely on or off on demand by an auxiliary channel.

The receiver installation is straight forward with exception. I believe that batteries and
switches are the most common failures so I use Red Schoefields recommendation of two battery packs and two switches plugged in to two separate sockets.

Due to the heavy engine and on board glow driver, this plane has weighed in at 20.9 pounds empty. Slightly heavier than the ones I have been reading about.

I have the plane balanced at the 5 3/8 inch point which is recommended the CG.

With a 22x8 prop the engine runs great and after about 10 flights is turning 6400 static.
It idles at 1000 to 1200 RPM and can be set as low as 720. At about 1/2 throttle the engine sounds just like the full size plane. The exhaust pipes are straight pipes made from 3/8 inch sink faucet supply tubes. They are chrome plated soft copper and are easy to shape. I installed a pressure tap in one of them. To sum it up the sound and low vibration is worth a lot of the cost.

The plane tracks fine on take off and climbs out smartly. It even has a lot of vertical, more than I ever expected. It rolls with very little elevator and tracks like it is on rails.
Now every plane has a dark size. As with any biplane, upon landing you must keep the nose down and speed up. It will full stall (three point) land if your judgement and timing are perfect.

Kmot

My Feedback: (24)

In one post you said turn off my speakers and that is what the FF-320 sounds like. In another post you said one of the great features of the FF-320 is the sound.

proptop

My Feedback: (8)

Nice post Dan...
AJCoholic also did a review of this engine for Fly R/C mag about a year or so ago.

iflyj3

My Feedback: (7)

That is correct. I said "To simulate the FF-320 idle, turn your PC sound completely off and watch the prop turn." Notice I said at an idle because the engine is so quite.

Above the idle it sounds great and quite also. The sound of the FF-320 engine at 1/2 throttle, which is about 3000 RPM, is close to the full size engine. I cruise my J3 Cub at 2150 RPM for normal cruise and 1950 RPM just loafing around and the OS sounds similar to the Continental it looks like. At full throttle, it sounds like a high speed sewing machine. The sound of the FF-320 is slightly louder than some of the real large electrics.

Sorry to confuse.

RSL_Mongoose

Thanks for the info iflyj3, I plan on getting started next month on one, only difference is I plan on using s9202 or s 9252 servos, I have been using those on helis for the past 5 years or so.

iflyj3

My Feedback: (7)

I've tried to upload a couple of pictures of the engine installation and no joy. RCU and slow dial up won't let me. I'll try from the shop today as that line is twice as fast as this one at home.

I'll try this again. Pictures that is...

More HP

My Feedback: (2)

Me too, I'll trade my first born (she's even learning to fly a little!)for a good video of the mighty pegasus running through different RPM ranges without any goofy background music.

RSL_Mongoose

What is the purpose of the right thrust? I have seen it on a buddy's planes.

iflyj3

My Feedback: (7)

To counter the left turn caused by the torque of the engine and the P-factor.

P-factor is caused by the prop blade on the right side having more angle to the relative wind than the the prop blade on the left side. This causes a left turn anytime the airplane is in a climb attitude.

In my opinion, the engine torque is a much larger left turn force than the propellor factor.

Does flying inverted cause a problem? The right and down thrust is based on the condition you will always be right side up, as in a passenger plane.

RSL_Mongoose

Ahhh So its basically the same as a Heli, if you wattch a heli in hover you will notice that it always tilts toward the right (if its a right hand rotation head), no way to counteract it on a heli.

William Robison

My Feedback: (3)

Mongoose:

Quote:

ORIGINAL: RSL_Mongoose
...basically the same as a Heli... heli in hover you will notice that it always tilts toward the right...

Not really.

Let's assume, as you said, the rotor turns clockwise looking from the top. This makes the torque reaction tend to turn the fuselage to the left, and the tail rotor has to push to the right to keep the fuse from turning. Then, since this side thrust is at the tail end and there's no matching thrust in front, the net effect pushes the entire heli to the left. Tipping the rotor cone to the right allows a stable hover, without going either way.

This effect is also why some heli instructors advise putting a block under the left skid while learning; with the bird slightly tipped to the right it's felt that taking off into a hover is more easily learned.

In forward flight another little nasty comes into effect, adding to the uneven aerodynamic forces noted in a hover. To an extent it somewhat cancels the hover conditions.

In forward flight there is a difference in the airspeed of the leading and trailing blades. Let's posit a 38: rotor diameter, and a head speed of 1800 rpm. This gives a rotor tip speed a hair over 200 mph. In a hover, all blades "See" the same air speed, but then we transition to forward flight. At a forward speed of 50 mph, the leading blades have an effective tip speed of 250 mph, while the trailing blades have slowed to 150 mph. Naturally, this transfers the center of lift to the left side of the rotor cone, and there's your right turn tendency. An adjustment of the cyclic compensates of course, just the opposite of the correction needed for a hover.

Way off topic for this thread, but I hope it helps.

Bill.

RSL_Mongoose

I have three and they all tilt to the right in a hover and I still block the left side of my FAI machine up on the left, it makes for a very smooth liftoff in a contest, as far as the rotor tilt goes, it doesn't matter if the tail rotor is on the right or left if a right hand rotor will tilt the machine to the right.