Wot 4 XL Mk 2 - Build

[Paul Thompson 1]

Good of you to do a crash test too, very thorough!

Installed the engine in mine this week (MacKay 24cc) and found that the issue with cowling has also been fixed, my cowl is 152mm long and instructions state to mount engine with overhang of 140 - 145mm so is now correct; maybe someone read your review, good to see manufacture's on the ball.

Though it looks to be pretty well glued in have glassed the undercarriage plate just in case...

[Jim Pearce]

Thanks for all the great info on this thread, I have a CRRC PRO 40cc in a y2k Giles and it's been excellent.

What is the exhaust pipe you have used on the 26cc CRRC pro engine please? The stock mufflers are pretty load I assume you found that to?

thanks Jim

[Paul Marsh]

I wonder if Ripmax will every release the XXL Wot4? I doubt it, as I've got a 45 petrol waiting to go in somewhere. Here's a photo from Nurenberg a couple of years ago.

I wonder if the prototype model still exists, and is for sale?

[Paul Adams]

The one fitted to mine is:-

This one

I had to do a very slight bend in the header pipe using a plumbing 22 mm pipe bender to get a good fit.

(The standard exhaust is a bit noisy).

Regards Paul

Edited By Chris Bott - Moderator on 09/04/2012 21:19:26

[Chris Bott - Moderator]

Paul could I ask you to read this tutorial? We know its a pain but until the techies sort this out we have to remember the correct method. I've altered your link above to sort out this page.

Thanks
Chris

Edited By Chris Bott - Moderator on 09/04/2012 21:22:49

[Paul Marsh]

Wot? I did it right, unless there is something we've missed...

[Paul Marsh]

I can't add links, unless I use the Laptop under Ubuntu, which means messing round, etc. Also the internet today has been so slow, usually timing out, or taking 5 mins to load a page.

Edited By Paul Marsh on 09/04/2012 21:27:51

[Chris Bott - Moderator]

Paul M - I was referring to Paul A. If you look in the post above mine it has been edited by me, I had to change a long link as it was messing up the page. Nothing to do with you

[Paul Marsh]

That's confusing. two Paul's. I know, next door is called Paul, and a friend at school was called Paul, so am looking round, but not me.

[Jim Pearce]

Thanks Paul A!!

So another question if I may?

Your running a CRRC Pro 26cc, is it powerful enough? Could you tow a glider do you think? If you were starting again would you choose this or the DLE 30cc?

Thanks a lot mate

Jim

[Paul Adams]

Most of the time I fly on less than 1/2 throttle. At full throttle it will climb vertical without loosing speed. I have no experience in glider towing, so can not state if it would have sufficient power. The CRRC 26 engine is specified at 2.5 hp, which is quite a lot less than the DLE 30cc, so if its brute force you need the DLE could be the best bet.

If I was starting again, I would have no hesitation in choosing the same engine. The only problem I have is slowing the model down enough to loose height for landings, as even on tick over with a 16 x 8 prop, there is still sufficient pulling power from the engine to maintain height. I did try a 18 x 6 prop but found it unloaded in many of the aerobatic manoeuvres, so have gone back to the 17 x 8 and use the ailerons as flaps for landings.

Regards Paul A

PS Sorry Chris about not linking correctly.

[Jim Pearce]

Great thanks! Jim

[Paul Thompson 1]

My XL is about 80% complete now but have hit a major snag, it's grossly nose heavy?

Fitted with MacKay 24cc on Dubro alloy mounts, APC prop and alloy spinner the 2 battery packs would need to be mounted halfway between wing and tail for it to balance correctly. I've considered cutting a hatch in fus behind servos and mounting packs in there but fus has lightening cut outs in the sides which gives little to attach the packs to. My only option would seem to be mounting the packs above or below the servos and will then need 4 - 5oz tail weight.

I think the reason for this discrepancy is twofold, firstly using the slightly heavier alloy mounts, secondly my engine is mounted further forward, about 148mm from bulkhead to prop driver.

[Jim Pearce]

I have a Y2K 27% Giles 202 and when i put a CRRC Pro 40cc up front I had the same problem with balance.

To solve it I put the flight pack (I use DeWalt a123's) in the tail, right at the back and I ran a cable for power, this is working a treat and saved lots of lead.

Set her up with some Tape and your pack mate

Cheers Jim

[Turbycat]

I hope you guys are being more gentle with your XL than me then. I fitted an Evolution GT26 to mine for a bit of fun. Damn near pulled the airframe apart! I went back to an OS 91 FX and it flies nicely on that and will pull out vetically from a prop hang. I think a 120 2 stroke would give more vertical punch in this but I wouldn't go for more, unless you were using it to aerotow some serious sized models.

Andy

[Paul Thompson 1]

Putting battery packs at back of fus is impossible due to lack of space and the rudder/elevator linkages, so I cut a hatch under fus just behind servos and installed them in there, tight squeeze but just fits, model now balances with just 1 1/2 oz tail weight.

Despite my previous post, the fin was still too short by exactly 3mm, no big deal though just cyano'd some 1/8" balsa to it and sanded it down.

The covering on mine was wrinkled in places and discovered that covering hadn't been properly shrunk so went over entire airframe with film iron & gun, a lot of shrinkage took place to secure the covering.

Initially I fitted the supplied control horns to elevator & ailerons but these were terribly sloppy giving an unacceptable amount of free play, so these were replaced with some Flair ones I found in my bits box. Also used thread lock on the metal clevises & lock nuts.

Flew the XL yesterday in variable conditions, weather started out with blustery cross wind, then a hail storm followed by half hour of blue sky and flat calm before returning to blustery cross wind, so experienced all weathers in one afternoon, typical English summer I suppose!

First impression was how fast it was, MacKay 24 turning an APC 16 x 8 and it howled round like a pylon racer at full throttle, flying round at half throttle and model would still loop from level flight with ease so I'm sure it would fly on a good .60, especially considering that model would be much lighter too.

Trim wise 2 clicks of right aileron and 1 click of up elevator had model flying hands off, inverted required only a touch of down to maintain. I had built in 1.5 degrees of right thrust and this seemed about right as model tracked straight up vertical.

Needed a lot of opposite aileron mixed in with the rudder, around 20% on my DX8.

Tried everything I could think of in one afternoon including pos & neg flicks, upright & inverted spins and model performed perfectly, comes out of spins with no fuss, very safe and predictable.

Obviously not up to F3A standards but a brilliant all round aerobatic model; if I wreck it will have no hesitation in buying another.

Edited By Paul Thompson 1 on 18/04/2012 11:19:30

[Peter Wood]

Would a 65 4 stroke be ok

[Paul Thompson 1]

I think a 65 four stroke would fly it ok, but may be limited for aerobatics as it won't have the power of a 60 two stroke. Depends what you want from the model.

[Jim Pearce]

Cheers Paul.

 

I assume when you say mackay24 that's a petrol? Do you happen to have the weight of the engine you could share?

I am thinking CRRC Pro 26cc V2 which is 860g with ignition excluding exhaust.

 

Thanks Jim

Edited By Jim Pearce on 18/04/2012 11:50:09

[Bob Cotsford]

Sorry to disagree, but I think a 65 4st would be disappointing in the extreme. A 120 4st is ok, a 90 might JUST do it but unless you fly from a billiard table I think anything less than a .90 would struggle to get it airborne. You are looking at an all up weight in excess of 9lb after all.

[Paul Thompson 1]

 

Jim,

Just weighed my other (rear exhaust) MacKay and it's 865grams bare, with plug but minus ignition, battery & exhaust so your CRRC seems to be considerably lighter.

 

Bob,

I disagree, the issue isn't about all up weight but of wing loading, I think a 65 four stroke would fly it but as I previously said would be limited in aerobatics, Using a glow engine would also mean less weight to carry further reducing weight & wing loading. Not something I would want to fly though, bit too sedate.

Edited By Paul Thompson 1 on 18/04/2012 12:49:31

Edited By Paul Thompson 1 on 18/04/2012 12:51:19

[Bob Cotsford]

ok Paul, in ideal circumstances a 65 4st might fly it after a fashion, but it definitely wouldn't be something I'd recommend, or even suggest. As I said, I consider it 'adequate' with a 120 4st, though a 120 2st would be 'interesting'.

Edited By Bob Cotsford on 18/04/2012 14:02:09

[Jim Pearce]

Thanks Paul CRRC Pro will be ordered, will report back results.

Cheers for your help Jim

[Paul Thompson 1]

Posted by Bob Cotsford on 18/04/2012 14:01:30:

ok Paul, in ideal circumstances a 65 4st might fly it after a fashion, but it definitely wouldn't be something I'd recommend, or even suggest. As I said, I consider it 'adequate' with a 120 4st, though a 120 2st would be 'interesting'.

Edited By Bob Cotsford on 18/04/2012 14:02:09

We'll agree to disagree Bob, nice to have a sensible debate without things getting personal.

[Calvin Higgerson]

Just started assembling my xl today, the fin still isn't long enough. What a pain the elevator rods are,even with the fin and stab not fitted, I'm waiting for an rcg20 to arrive to fit in it. The firewall isn't drilled for the engine mount despite the instruction saying it's pre-drilled. While working on the wings I noticed a large square hole under the covering on the underside of the right hand wing, I take it this is for the optional glider tow release mentioned on the box, and where the square plate in the fittings goes. I won't be using the horns supplied as I don't think they are really up to the job. If anyone has pictures of their petrol installation they would be helpful as to where to fit the ignition/throttle servo etc. I'm quite pleased with the build so far and it appears to be quite well built.

Thanks

Calvin