I bought a 3W Fun Xtra from Cactus aviation around Christmas and it has been a endless headache.

The instructions are terrible and in German to boot. The engine install is terribly obscure. (This is my first gasser, so I may just be stupid) I have called Cactus and while they have been friendly, they have not been very helpful.

I had to solder a throttle arm on the engine (on what is supposed to be one of the premier brands of gas engines). Then when I finally get the engine mounted with the throttle and choke, the canister muffler install begins. The screws are much harder then the engine head they screw into, and both screws immediately cross thread. One hour later, after much cursing and sweating, on about the fifth attempt to install the header, one of the bolts breaks off in the engine.

Now I will have to send the engine back to 3W if I can't get the bolt out. It makes me want to scream.

I don't know how much of this is poor design/instructions from 3W and how much is my own inexperience with gas. I have been flying glow for years and you would think I could install a muffler, for pete's sake. I don't think I will be buying any more 3W products, though.

Leonard

You have instructions????

Thats better than a Fiber Classics or a ZN Line kit. Those might have a picture that looks like it was drawn on a napkin on a late night at a bar. If your lucky, you may get a CG.

I have a 3w24, 3w 80, and 3w 100 TOC. I have never had a problem with setting up the throttle or installing a header or muffler.

I wouldn't trash 3w because you couldn't install a header or assemble an ARF plane.

Todd

Almost 800 dollars for a 80" fun fly and crappy instructions and problems. I would send that baby back in a heartbeat. I cant believe they can get people to pay that much.

My Synergy 90 ARF did not even come with instructions......

My Synergy 140 came with excellent drawings...

I realize that some of the problems may be from my inexperience with gas engines. However I have built at least 20 RC planes (most kits, not ARFs) and never had this much trouble with any plane. The problem with the muffler it that the threads in the engine head are TOO SOFT. The bolt would go in EASILY 2-3 complete turns before it became difficult to thread and by that point the mounting hole was cross threaded. Within 5 minutes of trying to bolt on the muffler, both holes were cross threaded and I was in trouble.

I may not be a gas engine expert, but I can install two bolts.

In retrospect, I should have stopped at that point and tapped the holes. I managed to get through the difficult things - a very obscure engine/throttle/choke install. I got the cannister muffler in, and when it came time to just install two little bolts I ran into big trouble.

Leonard

If the bolts would go in straight for 3 full turns how did they then get crossed? I suspect they weren't quite straight when they started. Ive spun wrenches for years so I have a pretty good idea what makes something cross thread........putting them in crooked.

I didn't say they went in straight, I said they went in easily. The engine has to be mounted at an angle, and the header comes off the engine at a different angle.

The screws would go in at what appeared OK, then would bind after several turns, and it would be apparent that they were crooked. The fact that the header is a bolt-on rather than bolt-through design means a ball driver is necessary to install the rear bolt, and telling if it is straight is a matter of feel.

Leonard

Just to throw my 0.02 in. Recently I watched a BMW breakdown right after a complete overhaul, the reason being that the brand new oil pump was faulty. The local BMW manager said that we were the unfortunate 1 in a million that got the bad one out of the lot.

Sounds like you may have gotten the same bad luck

I know the guy that made those drawings. He made them for him self but then he sent a copy to ZN an then they decided to youse them.

You may have been trying to use the wrong bolts, a 10/32 is very close and will thread in a few turns before the binding begins, the 3W cylinder uses a metric bolt witch I think is a 5mm, If you were to put the two side by side you would be hard pressed to tell the two apart. Been there done that.

The bolts I used were the ones that came with the kit, they took a 3mm allen head wrench.

I guess I will try out the 3W service now.

Leonard

Hello, If the threads are not totally screwed up you may want to try cleaning out the treads with the correct size tap
if they are totally buggered up you can get a helicoil repair kit
avail. at most auto parts stores
as sending the motor in will proably cost you a new cylinder.



Frank

He has one broke off though I believe. If you don't feel up too the task of taking it out take too a local machine shop. Unless Cactus will do it as warranty work you ll save a good bit. IF you try it yourself, try taking a small chisel an carefully tap the bolt counter clock wise too remove it. Or use a mig welder to spot weld a small nut unto the bolt. You don't have to worry bout the weld sticking to the aluminum head. Few other things you can do but those are probably the easiest.

Dan

Managed to get the broken bolt out. I re-drilled the hole slightly larger, tapped it for 8-32 threads, and the header mounted on the first try like it should have in the first place.

Interestingly, I was going to try tapping it for the original size bolt. When I went to the hardware store, the other bolt (the one I didn't break) appeared to be a M4 bolt, but was very slightly loose on an M4 nut. It didn't fit any other english/metric nuts, clearly the M4 was the best fit and it would screw into the bolt completely. So maybe the problem was slightly off-size bolts, and not with the engine itself.

In any case, the header is installed and I am back to where I was Monday night.

Leonard

New frustrations, but some glimmer of hope.

CG problems. Rec CG is 25% MAC, very conservative for this plane. However measured CG is 37.8% MAC without batteries, and even with the batteries as forward as possible, it will require 8+ oz of firewall lead. I am shooting for 31-33%.

The good news: AUW is 10 lb 15 oz (without the extra lead). Also, if I switch from a tail mounted rudder servo to CG mounted pull-pull, I should save most (or all) of the lead. A 2 oz servo mounted 40" aft of CG equals 8 oz lead on the firewall 10" in front of the CG.

Oh well, I think this is the slowest ARF I have ever built (and it comes with the tail mounted and no wings to join!)

Leonard

PS Under 11 lbs on a 78" span extra - I have got to get this thing in the air!

Leonard,
I am flying a JR Models DiablotinXL with a ZDZ40RV engine. This plane is 87.5" wing span and length (long mother) and although I have not had it on the scale, I estimate it to weigh 11 lbs as well. This ARF also took me some time to assemble, but I double bevelled all tail surfaces and recovered. I have had the Diablotin muffler break on me and am right now in the process of soldering up a Crumscheib header and mounting a KS can. Why did you go with the more expensive and smaller 3WExtra and 3W24i engine? I will admit it looks like a great plane, but if the DiablotinXL is available cheaper, I would chose that plane. The DiablotinXL has double reflexed wing ribs and is just a dream to fly. As I am working on mine I am also moving radio gear around to get CG further back. CG is about .5-1" behind recommended without adding weight.
DKjens

I guess I went with the Xtra because I liked the looks of it, and because it came as a complete set (engine, ARF, and exhaust system), and it will be my 1st gasser.

I am almost ready to fly it. I have moved my rudder servo from the tail to the CG. I hope I don't end up moving it back again.

Leonard

Maidened the Xtra today. I am still getting used to it, but the 3W engine is a honey. Starts easily, low and steady idle, instant response, and all this with only about three full tanks through it.

The plane looks like it will hover at less than half throttle.

After all this work, it looks like it will work out fine.


Leonard

I have one of the 3W Xtra Funs as well, with the 3W-24 and canister. All up weight is 11lbs with no nose weight. The rudder is setup pull pull as well. I can't comment on the building since I picked this one up from a fellow pilot used, but it appears to be well put together.

What I can comment on is the flight characteristics. I've put a few flights on it now, and mine hovers around 1/3rd throttle. It has incredible control responses, and feels like it weighs 5lbs. Even with the extreme throws this bird has, it can still fly a very nice precision pattern if dialed back. Let the sticks fly, and its a very nice and light gas fun fly. I've also flown the DiablotinXL, and in my opinion, this one flys better 3D. I think the wing design differences has a lot to do with that. Blenders and knife edge spins really look particularly nice on this plane. I appreciate the longer tail moment in some of the maneuvers as well.

Out of curiosity, what prop are you running on your 3W-24? I've got a 18-8 on mine, but I need a 19-8 or 20-8 instead since its just about over the max rpm figures. I assume you have run this airplane quite a bit since your last post was in Dec.

I run a 3W 18x8 (which came with the plane/engine) - at least I did until I took the gear off and broke the prop.

As has been noted on RCUniverse before, the gear mounting is very flimsy. I don't think I have ever had a .40 size plane with less support for the LG mounts.

It did survive about 10 flights with the stock gear mount before ripping off on a (slightly) bouncy landing. I knew the gear was flimsey, and was careful to make very soft landings, but after a while I got a little sloppy and that was all it took.

The plane flies very well. It hovers at just over 1/3 throttle, but even at full throttle is not very fast (and that's OK). It will knife edge forever with very little elevator/aileron input.

Mine would corkscrew with high elevator throws. I don't think the plane is tail-heavy, but I never checked a lateral balance, so maybe that is the problem.

The engine was tuned by a few gas guys at the field (I am a total gas newbie) and has been flawless ever since. Despite my initial griping about 3W, they make one heck of an engine.

I need more time on this plane, but I think it is a real winner. If it only landed as well as it flies, it would be perfect.

Leonard

Leonard,
Happy to hear you're pleased with the plane -------------------- after initial "gripes". I actually finally got my DiablotinXL on a scale today, what a kick in the groin that was ------------------------ 20 lbs fully fueled and ready to go. I suppose that is still light for the wing area, but it's much, much heavyer than I had expected oh well.
How is the Extra hard to land? Does it balloon up when slowed down (tail heavy) or does it want to bounce after initial touch down. A trick I use to make me look really good is as soon as the plane touches down I flick the switch on my Rx to turn the spoilerons on. I use a bit of spoilerons in elevators and harriers, and when used during landings they take all lift away and the plane sticks to the runway. They are also a good little tool to have if deadsticking it or coming in a little to hot and/or high, flick them on on the approach and the plane drops 100% faster, flick them off for final glide, and then on again at initial touch down.
DKjens

The extra is NOT hard to land. It is light for its size and floats in. The problem is that you have to land smooth and slow because the LG is very weakly mounted. If you bounce at all, hit hard (even a little), or touch down fast, the gear is coming off.

Every landing needs to be greased in perfectly. It flies so well that I got 8-10 near perfect landings before I took the gear off.

The LG plate is 1/8" ply (or a metric equivalent). It is about 3" by the fuse width. There is 1/8" square balsa reinforcement where it joins to the fuse side, and two triangles of 1/8" ply. That's it - no triangle stock, no thick ply, no FG. This on an 11+ lb gasser. The design is light, light, light. I like light planes as much as the next guy, but I am not a good enough pilot to land this plane consistently (on our grass field) as it is. Now that the gear is off, I will try to come up with a permanent solution.

Leonard

hi

how much fuel do you bring? 1lb?