mrbonk

The control surface horns are quite sturdy. They are very solid once screwed down. Normally, I would use a bolt and nut with a large washer on each side of the control surface to achieve an arrangement like this, but these work very well. Just make sure you drill the holes through the control surface nice and square, or you'll spend the next half an hour trying to push the screws in or out to meet the holes in the backing plates

mrbonk

This model has ditched the traditional cabane arrangement (thankfully!) in favour of a centre mounted 'pylon' for the top wing. The holes for this are already cut into the nose deck sheeting and bracing is fitted to the formers underneath. I taped the assembly down to hold it in place while the epoxy set. There is a gap at the front of the pylon that could probably do with filling from the inside, but you can't get to it. Fortunately, the cowl will need to have a slot cut in it to fit around the pylon, so it will cover the gap.

mrbonk

Time for a quick test-fit of the wings....just 'cause I can't help myself I just want to see what it will look like when it's done.

mrbonk

Time to start work on making the cowl fit properly. Along with the slot that needs to be cut in the top, I had to remove the bottom of the 'bulges' at the bottom corners of the rear of the cowl, right in front of the landing gear covers. I'm not sure if World Models intended for the builder to have to do this, but if you don't, there's no way you can get the cowl back far enough to clear the spinner at the suggested distance from the firewall. Either way, the dremel makes short work of it.

mrbonk

The bulge, removed.

mrbonk

My aileron servos have finally turned up. As I mentioned in one of the first posts of this review, I ran into a problem getting a standard servo to fit in the wing, so I've gone for 'Mighty Mini HS225BB Hitec' servos. These are doing 3.9kg of torque at 4.8v, so should be more than enough for this model. You're required to epoxy a couple of balsa blocks to the underside of the hatches in the wing to mount the servos to. A couple of the blocks that were supplied with the kit were quite soft, so I replaced them with some harder balsa stock I had already. I'm not that keen about putting servo screws straight into balsa block, so after I had the blocks attached and I'd run the screws in and out, I put some thin CA down the screw holes for strength, then soaked the outside of the blocks in thin CA too. They're much stronger now. Same goes for the screw holes for attaching the hatches. These go into lite ply in the wing, so I gave these holes the CA treatment too.

You'll see I had to use the adjustable length arms to get them poking far enough out of the top of the hatch. Unfortunately, the longest standard horn supplied with these servos just isn't quite long enough. I may see if I can get some longer standard ones and get rid of these adjustable ones (which I'm not that keen on using).

mrbonk

The aileron control rods are short/thick enough to avoid any flexing and you're supplied with short lengths of fuel tubing to slip over the links once they're on. No way any of these are coming loose!

One thing I'm not keen about is just leaving these hatches screwed down with 2mm screws. I've got some Prather Radio Box Tape, which I'll be using to seal the edges AND cover the screw heads once I'm finished with the servo adjustments. That way, the screws can't vibrate and come out. Given that the hatch is the only thing holding the servo in position, I think this is an important thing to do.

This is what the entire thing looks like with the hatch on.

mrbonk

After some measurements were made on the clear half-cowl, it was time to take to the real one with the dremel. Fortunately the half-cowl lined up perfectly so all I had to do was start small and just keep making the holes bigger a little at a time until they were right. There's no real 'gotchas' with this.....just take your time and only do a little at a time. Don't just hack away blindly!

mrbonk

You'll need a needle valve extension wire. I just used a piece of an old pushrod I had. The needle on the YS comes with a tapped grub screw hole for exactly this purpose

mrbonk

Here it is, with the prop and spinner installed. It looks very neat, even if I *do* say so myself
A tip here - the screws that hold the cowl on just go straight through the side of the fuse. You need to put some CA down the holes *after* you've put the screws in and out once, just to coat the threads (for strength) and seal the balsa against oil.

mrbonk

I put the pilot figure and the canopy on next. Same as with the engine cowl, the screws go straight into the fuse.....into balsa in the case of the top 2, so run CA down the holes again. I'm not overly keen on the pilot figure actually.....I have a couple of Eric Cartman toys around the place somewhere here, so I think one of those will end up in there shortly

mrbonk

Time to put the radio gear in. This is pretty standard fare, with a couple of birch (ish) rails for you to mount your servos on. No tricks to that bit.
The connectors you're supplied with for the pushrod ends are quite good. The servo end ones are the standard 'post' style ones, where you put the pushrod wire through the hole and secure it with a grub screw. Loctite is your friend here The wire ends of the pushrods weren't that much too long, so I didn't bother trying to cut them off. There's so much room inside this fuse anyway, you don't have to worry about catching them on anything!

mrbonk

To install the rx battery pack (I'm using a 4-cell sub-c 1200mah nicad pack), I epoxied a piece of thick balsa to the rear of a former and zip tied the pack to it (with some foam under it). The former is almost exactly on the C/G of the model, so the pack position doesn't alter the balance at all (which came out spot on I might add, with no weight required ).

mrbonk

Here's the pack, installed.

mrbonk

I've chosen to velcro-strap the RX to the same former that I've mounted the RX battery pack to. This will enable me to get to the sockets to plug the ailerons in when I assemble this beast at the field. I've used some Dubro rubber mat to wrap the RX in. This stuff is simply the best thing I've ever found for vibration isolation. The velcro-straps I'm using are actually intended for securing electrical/computer cabling. I got a heap of them from a network installation tech ages ago....they're perfect for when you need to remove and re-install things at the field. The velcro is strong enough to stand up to the vibrations in my heli, so I'm sure it will do the job here

mrbonk

I've used a JR Gold switch in this model.....big and sturdy! You'll also notice in the attached image that I've got the charge jack from the switch harness poking through the fuse side. I do this with all my models. It's so much easier to get at to charge up at the field.....no removal of hatches etc required. It's held in place with thin CA, then sealed from the inside with thick CA. Just make sure you don't fill up the pin holes with CA. Don't laugh...I've seen it done!

mrbonk

Next step is to fit the top wing and interplane struts. You're required to drill the mounting holes in the struts and the lugs in the wings yourself. For this, I used the longest 3mm drill bit I could get my hands on, in my Dremel. The only issue I encountered here was getting the Dremel down close enough to the wing to drill the hole square. I got it down as close as possible and it worked fine. The best way to go about this is to put the interplane struts on the lugs where they're supposed to go, then drill the hole through the whole lot. That way, the holes *have* to match up when you're finished. A word of caution here.....there *is* a right way and a wrong way for the interplane struts to go. You'll have to look carefully at the tops (or bottoms....) and work out which is the right way up. There *is* and airfoil shape in them. Just make sure you get them 'round the right way.

mrbonk

Only thing left to do now is to fit the horns for the aileron link rods and make up the rods themselves. I'm told that you should put these horns as close as possible to the aileron control horns, so that's what I've done.

mrbonk

I took the model out in the yard today to run the engine up and set the idle etc. The spinner that was supplied in the kit lasted about 10 seconds, before one of the plastic mounting posts on the backplate broke off. Hmmmmmmm. Not a good start. At least I wasn't at the field with no spanner to remove the prop! After removing the remains of the spinner, I fired the YS.91 up and set the idle. Unfortunately, the muffler position of this engine fires the exhaust pretty much straight at the left wheel-spat, unless I rotate it all the way back, which then points it straight at the leading edge of the bottom wing......time for an exhaust deflector methinks!
All going well, I *might* be able to get to the field tomorrow for the test fright

mrbonk

I finally managed to get out and test fly this beastie. I've been waiting for a couple of weeks for good weather, which was not forthcoming. So, I bit the bullet and went out the the field today in fairly windy conditions for the first flight.

After 30 minutes or so of setting up (I have to take this thing totally apart to fit it in my car) I ran the engine up and set it slightly rich at the top, as per the instructions. I've actually fitted an onboard glow unit since my last update, but didn't get photos of it....oops! So, with a nice 2000rpm idle I was ready to blast off.

The model required a couple of 'beeps' of right rudder to keep it tracking straight into the wind down the strip, but didn't do anything unpredictable on takeoff. Once airborne, all it required was a couple of 'beeps' of up trim and a 'beep' of aileron trim to be flying straight and level at full throttle. Reducing power to half still sees the model flying straight and level and with more than enough power for 'normal' flight. In fact, in the 4 flights I had today (of 6mins or so each), I rarely raised the throttle above half. The YS.91 with a 15x8 prop is heaps of power for this model. It hangs on the prop (and torque rolls nicely) at a little over half throttle Snap rolls are quite violent (as expected), even at half throttle, and it tends to over-rotate by about another quarter roll after you let go of the sticks if you're snapping against torque direction. Snapping with torque produces an unbelievably fast snap, even with the recommended aileron throws, which continues for another half+ roll after letting go of the sticks Fun factor!!

The recommended control throws in the manual make the ailerons *very* responsive. Even at just above stall speed, they still have heaps of authority. The rudder has enormous authority and the elevator response is more than enough, even at very slow speeds. Slow flight is a no-brainer, with a nice gentle straight forward stall and no tendency to drop a wing. I should mention that I do have the C/G back further than where the instructions recommend. It snaps on elevator alone (at the top of loops with the recommended throws), but I prefer that to running out of elevator on landing with a forward C/G.

Landing (in the windy conditions) required approx quarter throttle to be held until it was ready to touch down. It *does* put the brakes on when you reduce power, but not as bad as some other bipes I've seen flown at my club. At 9 pounds, it's not *that* heavy for a model of this size, so I think that helps. The wire undercarriage really wobbles under the weight, but unless you really dump this thing on the ground I think it will stand up to the job.

The coolest thing (aside from the wonderful flight characteristics and the sound of the 4-stroke) is the rather loud 'howling' noise produce by the airframe in the wind. I'm not sure where this is coming from, but I suspect it's from the interplane struts. These aren't solid and the covering material 'sings' where they're hollow when you blow on them. I'll have to get someone to shoot some video for me (couldn't find anyone to do it today) and post it to the web. (Edit 24/5/2002 - I posted some .wmv format movies of the Ultimate to my web page....check 'em out!)

Anyway, that's it. I'm thoroughly impressed by every aspect of this model. The quality is fantastic, the performance is excellent and it looks absolutely brilliant in the air. Coupled with a sweet running 4-stroke like the YS.91, it makes for a very enjoyable model indeed....I highly recommend it

mrbonk

Short update on the Ultimate.
After a couple of weekends of flying this plane, I've had to do a couple of things. First thing was to brace up the undercarriage. The wire gear supplied with the kit is ok, but it's slowly bending under the weight. After around 10 flights (with no hard or bouncy landings in there), I had to bend the legs back down slightly. Today, I got some 5/32 piano wire and soldered a brace across between the legs, around an inch below the fuse. This has stiffened the U/C *considerably*, possibly even too much, but we'll see in the next few days. I'll post some pix of the modifications when I can get some. The other thing is that the pilot figure keeps coming loose inside the cockpit. Last flight on Sunday morning left him pressed up against the side of the canopy, looking like he was trying to get out Something to do with my flying style perhaps......either way, he'll be coming out permanently when I get a chance.

mrbonk

I tested the new U/C today.....fantastic. Way more sturdy and no hint of sagging now. It *is* more bouncy though, so now I've gotta be even more careful on the landings. It's easy to land, but the stiffer U/C makes it bounce *way* more than it did before.

I left the pilot in. I epoxied him in place this time, so he's not likely to come loose anymore.

I've decided to replace the split pushrod on the elevators. The 2 halves can flex just too much for my liking. I'm going to replace it with 2 separate servos with their own pushrod each. I'll post results when I test it!

mrbonk

I've installed pull-pull on all the tail surfaces. I *was* going to just use 2 servos and 2 pushrods for the separate elevator halves, but I decided to spend the time and convert the whole lot to pull-pull. It's *much* nicer than the split pushrod....no more differential movement of the elevator halves now. I test flew it today and it works very well. I also took the opportunity to move the C/G back a little further again. Now, it *almost* goes into a full-on inverted flat spin. I suspect it will only require a small amount more rearward C/G to get it there.

captinjohn

nice

DaleD

Resurrecting this thread with the hope of getting any additional information available.

Grateful for details on the control throws for each surface. I note the comments from MrBonk about the model being very responsive even at just above stall speed with the recommended throws. If at all possible, please share new recommended throws for sport flying.

Thanks

DaleD