Wot4 XL artf Build

[Rich too]

Haha! I bought a Zippy Lipo from HK and they last forever!

[cymaz]

Maiden flew the Wot4 XL.

Nothing major to report...boring really..however I will give a short report

1. If side mounting the engine, lateral balance is vital. I did this and only needed a click of left aileron.
2. My CG of 105 mm is just about right. However, will remove some of the added nose weight to move it back a little further. At the moment it requires a little bit of push on the elevator when flying inverted and it will not stall very easily.
3. Side thrust is 99% correct out of the box with this engine and mount. I may add a couple of washers to increase right thrust when I have got more used to its flying characteristics?
4. The rear elevator servo works well and I am glad I've done it.
5. The Evo engine is a great match. True, it's only had 3 flights today but there's more to come as it runs in. At the moment verticle is not unlimited but by the time it runs out of puff ite really too high to do see what it's flying like.
6. The 14oz tank is lasting about 15/16 mins. This will increase slightly as the engine gets leaned out and runs in. 
7. Placing the tank on the CG means no decernable change in the flying trim as the tank empties. The extra time and effort to do this was worth it.
8. The aluminium U/C works well so I might not change it after all 

Edited By cymaz on 27/08/2016 22:33:41

[Rich too]

Excellent, congrats

[cymaz]

Had three good flight again on Sunday

I have put in a little right/ down thrust and taken a tiny bit of nose weight out. More flying today to see how much this changes things. Should be improvement.

I will report back, hopefully with good news.

[trebor]

How are you getting on with it ? I,m tempted even though it's an Artf and I said I would not buy another. Could it be a good all round favourite that you can't leave alone and its got to be the first one loaded in the car.

[Mark a]

I have one these in my fleet, built it stock and stuck a ASP120fs in the front. Been flying it for a couple of years now without any issues at all a truly great model.

[cymaz]

So flew all afternoon with the XL. Needs a shade less nose weight, easy fix...just snip off the cable ties and remove a lead shim, then rezip.

The only fault I can find is that it really tucks under on full use of rudder, quite a shock if you are not used to or ready for it. Otherwise it's a great airframe. Very stable at low speed. How it's built will depend on performance. However taking your time and doing it carefully rewards you with a plane that eats up the sky with large loops, axial rolls and the easiest landing you will ever have. It's a short hop and you're in the air. The plane will rock its wings if you are too slow on landing giving you loads of warning that you are on the stall.

Just the ditch the hardware and get the bits you trust and know.

Will tell more when I've done the nose weight issue.

[cymaz]

 

 

 

 

 

 

 

 

 Sorry for the quality. Taken quickly on iphone by my pupil.....

It may look small but its closer than you think......(as the actress said to the gardener) 

Edited By cymaz on 29/08/2016 21:00:20

Edited By cymaz on 29/08/2016 21:02:14

[Shaun Robinson 1]

Some say I could do with a new phone or a half decent camera sorry for the poor quality!

[cymaz]

Don't worry Shaun...................it was a nice surprise

[Kim Taylor]

Posted by cymaz on 29/08/2016 20:14:54:

So flew all afternoon with the XL.

The only fault I can find is that it really tucks under on full use of rudder, quite a shock if you are not used to or ready for it. Otherwise it's a great airframe.

Just the ditch the hardware and get the bits you trust and know.

Will tell more when I've done the nose weight issue.

Hi Cymaz

Could you explain to me what you mean by 'tucking under' and if it does it on the specified throws, or you have given it a bit more for good measure.

One of the guys at our field on Monday commented that the rudder on his was 'a tad aggressive' although I don't know what his throws were.

Couldn't agree more re: the hardware, I've now replaced all of the clevis after I had one break whilst I was trying to persuade it over the servo horn. Also the supplied spinner is rubbish - after putting it on & taking it off a couple of times whilst setting things up, the backplate has stripped out so the screws wont hold. I've ordered an aluminium one to replace it. I've also replaced virtually every screw supplied, as they seemed to be made of cheese.

If I receive the spinner in time, I may take it to the field next weekend and get it maidened, if the weathers up to it.

Good work in getting it built and in the air though - I must admit you've shamed me into getting on with mine!!

Kim

[cymaz]

Kim, what I mean is using the rudder causes the plane to yaw in the rudder direction but also dips sharply as its yawing.

Try experimenting doing a flat turn....there is a a lot of opposite aileron needed to correct the wing drop. Any release of the aileron causes a quick wing drop. Because the wing drop is sharp it takes some practise to get the aileron correction just right.

I hope I haven't confused you further with my ramblings.

[Bob Cotsford]

I'd forgotten about the supplied plastic spinners - when I had a Wot XL the spinner exploded while setting up the ASP FS120! At least the WW XL comes with a decent ali spinner.

[Kim Taylor]

Posted by cymaz on 30/08/2016 23:04:16:

Kim, what I mean is using the rudder causes the plane to yaw in the rudder direction but also dips sharply as its yawing.

Try experimenting doing a flat turn....there is a a lot of opposite aileron needed to correct the wing drop. Any release of the aileron causes a quick wing drop. Because the wing drop is sharp it takes some practise to get the aileron correction just right.

I hope I haven't confused you further with my ramblings.

OK right, I think I know what you mean.

I'll look out for that, maybe experiment with a mix of opposite aileron to rudder if it proves to be a problem.

Kim

[Kim Taylor]

Just in the interests of fairness and balance with regard to the supplied hardware, I noticed that one of the clevis which I bought to replace those supplied with the kit was slipping on the threaded rod at the servo end of the elevator pushrod. Thank goodness I noticed it, I reckon that's a bullet dodged, but it just goes to show you can't rely on anything, so now checking and double checking all the linkages.

Also fitted the new ali spinner - looks good and at least it's secure so all good there. Unfortunately didn't get it finished in time for today at the field and the weather's now turned iffy and Alen my instructor isn't about tomorrow anyway, so earliest possible maiden is now Thursday, but don't hold your breath.

Kim

[cymaz]

I thought that the thread on the push rod was a 4-40 USA . I maybe mistaken.

[Kim Taylor]

Posted by Kim Taylor on 23/08/2016 16:03:55:

I've had the whole lot together and test run. With the lipo as received from H-K (storage charge) I got the following results using the aforementioned 16x10 prop:

Current 67.5A (Over spec I know, but I'm hoping it'll reduce in free air and one click down on the throttle reduces it below 65A)

Watts 1440.

These are from memory. I don't remember the voltage,, but doing the maths, it looks about right at around 21.5V, bearing in mind the battery hadn't been charged. I'll do a proper run in due course with a fully charged battery, which should bring the amps down a tad. The ESC, which I know is tight, didn't even get warm in the 2 mins or so of running which I did.

Further to the above, I've now done a test run with a fully charged battery and it's pulling 87 amps and producing 1880 watts, so waaaay over.

Off to SMC to get a couple of alternative props, possibly a 16x8 and a 15x10 to see watts watt (sorry).

I imagine that the APC electric prop is more efficient (or at least absorbs more power) than whatever was used in the manufacturers tests.

I'll also post over on the electric flight forum for prop advice.

Still moving forwards (slowly).

Kim

[cymaz]

Flew the Wot at Much Marcle under the "LMA trainer slot". Behaved its self impeccably.

After the show closed it was just myself and the Wot with Niel Tidy flying around together doing circuits and touch-and-goes. Model flying heaven in the company of a real gentleman.

Bliss

[Terry Walters]

Posted by cymaz on 07/09/2016 22:05:49:

Flew the Wot at Much Marcle under the "LMA trainer slot". Behaved its self impeccably.

After the show closed it was just myself and the Wot with Niel Tidy flying around together doing circuits and touch-and-goes. Model flying heaven in the company of a real gentleman.

Bliss

+ That's sounds just great Cymaz!

[Kim Taylor]

Copied this over from my 'prop selection' thread in the electric flight section, just to tie up loose ends!

I have just had time to run a couple of different sized props, with results as follows:

Using a freshly charged 6s LiPo in each case, on the previously tested 16x8, 86A , 1840w. 21.5v

Then fitted a 15x8 and recharged the battery and got 70A, 1550w, 22.1v.

All of the above are measured between LiPo and esc.

Unfortunately, still no means of checking revs.

I think what this is telling me is

1) The manufacturers recommended 16x10 on a 6s isn't just inaccurate, it's totally wrong!!

2) As I'm propping down, the motor is unloading and speeding up, so the current when measured static isn't dropping as fast as I'd hoped. (As previously stated, I can't measure the revs, but subjectively, the sound is a higher pitch, suggesting more revs).

From here, I've decided to use the 15x8 initially, based on the assumption that it'll unload a little in the air. Also, I've noted that coming only two 'clicks' back from W.O.T. reduces the current draw to 45A. If I get the magic smoke so be it, at least I'll know not to push things so far in the future!!

Test flight as soon as the weather breaks and the wind drops on a day when I'm not working and my instructor is available - should be about a week next Michaelmas.

Kim

[Tim Flyer]

I have also done a lot of Wot 4 XL flying. Mine had an OS 120AX 2 stroke in it. Quite a bit more power than needed!! Would take of almost instantly. Unfortunately i lost it due to a brown out. The motor is fine and I hope to build another,. I found them very very easy fliers and also easy to land. With the 120AX mine did run on a bit on landing if there was no wind. If I build another I think I will use tail mounted servos. The ballistic power of the 2 stroke 120 screaming on a 16x8 prop did cause some vibration issues and i remember the long push rod rattling at certain throttle settings. I also had some problems with the front of the wing rubbing on the bulkhead due to vibration/slight twisting in the air. I think it would be better if the wing was more positively located at the front with a curved slot on the bulkhead or flat section on the front of the wing to spread any loads. Maybe 2 dowels rather than the single slot? Anyway i think i may get another one for a fun winter and tug plane. They fly well in all conditions. In my view the best power plant for the XL Wot 4 is a 120 Four Stroke. I also put 3 inch pneumatic tires on which were great for winter muddy grass..I also found the aluminium undercarriage very good...i did reinforce the inside though. Happy flying!

 

Edited By Timothy Harris 1 on 27/09/2016 19:27:01

Edited By Timothy Harris 1 on 27/09/2016 19:28:35

[cymaz]

Flew the Wot4XL yesterday and removed the last of the nose weight. It now lands slower, spins easier. It will also stop quite readily out of the spin.

Not sure where the GC now is but if anyone wants to know the I will gladly put it on my rig and find out.

Also broke the tail wheel axle off. The wire must have become weak and snapped off where I soldered a washer on to it. HobbyKing do a lovely tail wheel but it's always out of stock! So I ordered one of these

[cymaz]

Fitted the new tail wheel. It's rather a nice piece of hardware....for £7.99!

Took it out today and flew it a lot. We tried to mix out the tendency to mix out the "tuck under" when using rudder. The first job was to see what if the side thrust was correct...it wasn't. Took out the washers and all was fine. A mix of opposite aileron was added. This reduced the "tuck under" problem....at the expense of now dropping the nose. Up elevator was then added. All this was done at 1/4 throttle. When 3/4 throttle was applied, the plane turned left on right rudder ! So it seems that the aileron mix was too much over riding the rudder effect. After 2 hours we had the plane turning the wrong way !! Still with some more adjustments at 3/4 throttle, this might be successful. Then flying at redruced throttle should make the effects of the mix linear. I hope this works out.

Despite things not going well, I've learnt a lot. More news later on in the month. Anyone else tried these mixings and had similar results????

[Bob Cotsford]

Can you use a variable weight on the aileron mix to reduce the proportion based on throttle setting? Easy on a Taranis using a global variable based on throttle position but I'm not sure how you would do it on other brands.

[cymaz]

I think it will be a case of trail and error

Fly, land, adjust, fly. It may be a tiring day on Saturday.