WOT 4-E (balsa) Mk2 ARTF chat

[Terry Walters]

Posted by Bob Cotsford on 06/07/2011 09:42:31:

19 oz/sq.ft isn't really that high for an aerobatic model you know. My Eros must be around 18oz/sq.ft and that's a big floaty thing despite it's 7 1/2lb all up weight. A little weight can be an advantage when you want to land on a blustery day.

 

 

Hi Bob - yes I now agree with you but going from a WOT4 MK2 Foamie (RIP) which I loved to the balsa one was a bit of a shock weight -wise yet the flying characteristics are quite similar. I was genuinely surprised at how slowly it can be flown.

 

It is dragging its backside around a bit and I am debating as to whether it is normal or whether the COG (with all the church roof already stuck on the front end!) is till too far forward?

 

TW

 

 

[Tim Mackey]

Despite the rather unique shape of the Wotty fus, it shouldnt really appear to be dragging its tail low - do you mean it may be still too far rearward, rather than forward?

On the ground, switched on and trims set as per flight, is the elevator flat or slightly raised when the stick is neutral?

How does she behave inverted - lots of forward elevator stick ?

[Tim Mackey]

Posted by Kevin J Lloyd on 05/07/2011 21:43:58:
My Wot4-E has completed almost 4 hours of flying most of which I have enjoyed but on Monday 4 July it met its demise just after take off at around 6 to 8 feet it suddenly went into a right hand inverted roll and crashed breaking its back, upon closer examination to find out the cause of this I found that one of the metal clevis's at the rudder had parted company with the pin which was still stuck in the nylon arm that attaches to rudder, I think I may be able to get away with a repair but I will reinforce it with fiber glass sheet on the inside.

 

Not sure I see how losing a rudder clevis could have caused such a problem?

[Terry Walters]

Posted by Tim Mackey - Administrator on 06/07/2011 16:10:09:

Despite the rather unique shape of the Wotty fus, it shouldnt really appear to be dragging its tail low - do you mean it may be still too far rearward, rather than forward?

 

Yes Tim thanks for being alert! I do mean that it may be too much to the rear still - its about 82mm now - Ripmax have told others that it should be 90mm rather than the 70mm shown in the manual. Others have been sceptical of that and calculated it to be about 82mm. 90mm seems a very long way back on the chord compared to other similar a/c?

 

Posted by Tim Mackey - Administrator on 06/07/2011 16:10:09:

On the ground, switched on and trims set as per flight, is the elevator flat or slightly raised when the stick is neutral?

How does she behave inverted - lots of forward elevator stick ?

 

On the ground sticks neutral elevator is just a smidgen up but it really is a small amount.

 

Inverted???? Moi? No - sorry Tim but that day is yet to come (ask my Seagull PC9 electric why it is waiting for a rebuild!) . If I had to guess I would say that bearing in mind the normal flight attitude you would expect the need for quite a lot forward stick - but that's only me speculating.

 

Cheers

 

TW

 

[Tim Mackey]

The wot 4 wing ( the old originals anyway ) were symmetrical in section ( and equal chord ) with no dihedral, and never required much down elevator to hold a nice inverted flight.

If you have a smidgen of "UP" when neutral, this rather suggests nose heavy

[Terry Walters]

Thanks Tim - I hadn't considered that it might be nose heavy - just hooked on the overall weight issue and the forever changing COG position - will coerce my test pilot (That's you Pete B!) into having a go at the revised Ripmax 90mm COG position when we can get together next and report back when done!

 

TW

[Brian Lambert]

"The wot 4 wing ( the old originals anyway ) were symmetrical in section" Lots of people think that but they are not symmetrical, a very subtle airfoil section. don't build one with the wing assembled inverted, very odd flying characteristics! There is a small amount of under camber at the rear part of the under-surface of the wing. Well there is on mine. I am not sure that the Chinese built ones are the same.

[Bob Cotsford]

Posted by Terry Walters on 06/07/2011 16:04:26:

Hi Bob - yes I now agree with you but going from a WOT4 MK2 Foamie (RIP) which I loved to the balsa one was a bit of a shock weight -wise yet the flying characteristics are quite similar. I was genuinely surprised at how slowly it can be flown.

I was surprised how similar my Foam-E and XL are to fly, one being a flyweight leccy, the other a 9lb 120 powered chunk. The only time I notice a difference is when things go wrong, then the big 'un shows it's mass by taking longer to recover.

 

As for wing section, the foamE is definitely seni-symetrical and I think the XL is, but I wouldn't swear to it.

Both of these fly better with the balance point at or slightly behind the recommended position, confirmed by the small amount of down needed to fly mine inverted.

[Terry Walters]

 

Posted by Brian Lambert on 06/07/2011 22:24:56:
"The wot 4 wing ( the old originals anyway ) were symmetrical in section" Lots of people think that but they are not symmetrical, a very subtle airfoil section. don't build one with the wing assembled inverted, very odd flying characteristics! There is a small amount of under camber at the rear part of the under-surface of the wing. Well there is on mine. I am not sure that the Chinese built ones are the same.

Hi Brian - thanks - the wing looks fully symmetrical to me and quite well built and certainly better covered than my last attempt.

 

Posted by Bob Cotsford on 07/07/2011 10:49:04:

I was surprised how similar my Foam-E and XL are to fly, one being a flyweight leccy, the other a 9lb 120 powered chunk. The only time I notice a difference is when things go wrong, then the big 'un shows it's mass by taking longer to recover.

 

As for wing section, the foamE is definitely seni-symetrical and I think the XL is, but I wouldn't swear to it.

Both of these fly better with the balance point at or slightly behind the recommended position, confirmed by the small amount of down needed to fly mine inverted.

 

Hi Bob - looks more and more like I will be taking some of the weight off again - a very small amount at a time subject to agreement with my test pilot!!

 

TW

[Terry Walters]

Flew the WOT4 again today with more weight removed and I have to say it does fly very much like the foamie and I really like it now. I'm now down to 60gms of ballast and the COG is still slightly in front of the revised 90mm position stated by Ripmax. More may yet come off but I will fly it for a few sessions as it is before I decide to revise the COG.

 

I have to admit I've gone full circle on this one and can now genuinely recommend it to others - I think I'm going to get quite attached to it!

 

Thanks then to my original test pilot Pete B who bravely went where I feared to tread , Bob, Brian and Tim for their good advice.

 

Not forgetting Kevin who went through all the grief before me!

 

TW

[Scruffmeister]

What size servos are needed for this model? Everywhere I look it just says "four suitable servos"!

 

What sort of flight envelope is possible with the recommended motor (2820/05) and 3s LiPo - does it have unlimited vertical climb?

 

Thanks.

[Alan Randall]

Posted by Scruffmeister on 22/11/2011 22:52:58:

What size servos are needed for this model? Everywhere I look it just says "four suitable servos"!

 

What sort of flight envelope is possible with the recommended motor (2820/05) and 3s LiPo - does it have unlimited vertical climb?

 

Thanks.

I am also wondering about servos sizes and would also welcome advice on this.

 

Maybe Terry who has done a review could help.

 

Alan

[Terry Walters]

Hi Alan/Scruffmeister.

 

I am using HobbyKing 939MG (Metal Gear Servos 2.5kg/ 12.5g/ 0.14sec) all round.

 

I use them a lot on my stuff and found them fine for the Wot4 which I love flying(despite my early reservations about the weight and COG issues!)

Terry

[The Flying Pig]

Am very tempted by this model, but worried about the weight and C of G comments.

Has anyone an 'ideal' set up?

[Terry Walters]

Posted by The Flying Pig on 17/12/2011 11:56:27:

Am very tempted by this model, but worried about the weight and C of G comments.

Has anyone an 'ideal' set up?

Hi,

 

I am using an E-Max 2820/07, 13 x 6.5E prop with 3s 2200 (Nano) or 2300 Lipos.

 

You may want to exchange some of the lead for a larger power train rather than carry around dead weight. I'm happy with it as it is! There must be many variations on this model out there that owners might want to share..

 

It is great to fly and easy to place it where you want because of the weight - so it not really a handicap.

 

Terry

[Alan Randall]

Thanks for your info Terry.

 

Does then E-Max 2820 motor mount fit the pre-fitted captive nuts OK

 

Alan

[Terry Walters]

Posted by Alan Randall on 19/12/2011 09:22:34:

Thanks for your info Terry.

 

Does then E-Max 2820 motor mount fit the pre-fitted captive nuts OK

 

Alan

 

 

Sorry Alan - no it doesn't but all you need to do is make a template of the pre-fitted holes and transfer then to the motor mount and drill new holes in the arms to suit. Best if you have a pillar drill for it tho'. If I can do it.....................................

 

Terry

[Alan Randall]

I have discovered that the Giant cod / 4 max 35XX motor mount fits the captive nuts on the Wot 4 e without any modification.

 

I intend using the Giant Cod XYH 3548 motor which has the same dimentions as the Quantum Motor but with a little extra weight. Haviing read the cg saga, the extra nose weight may be useful.

 

Alan

[Phil 9]

Posted by Phil B on 04/02/2011 17:41:32:

I wonder if we will see ARTF Acro Wot's in the future

 

 

An electric on of these may be good

Now it is here

[confucius]

I have discovered that the Giant cod / 4 max 35XX motor mount fits the captive nuts on the Wot 4 e without any modification.

 

I intend using the Giant Cod XYH 3548 motor which has the same dimentions as the Quantum Motor but with a little extra weight. Haviing read the cg saga, the extra nose weight may be useful.

 

Alan

Hi Alan any up dates on your set up,

im looking at getting one for doing my A test with

Andy

p.s. what kv motor is you have used

Edited By confucius on 17/02/2012 15:23:34

Edited By confucius on 17/02/2012 15:29:12

[Alan Randall]

Hi Andy,

I have finally finished putting it all together today. progress has been slowed by the temperature in the garage. Just waiting for some decent weather now.

The motor is a 790 / 800 Kv which I am trying on a 12 X 8 prop for a start. Even with this I have added about 70g of noce weight to get it to balance at 90mm.

I must say that the battery hatch is a bit tight for anything larger than a 2200/2300 size lipo. I have sourced a 2600 from GC which is only a little longer than a 2200/2300 and fits OK, but only just.

I will report back after my first flights.

Alan

[confucius]

Hi all, post No2. as i said im looking at getting the wot 4-e mk2 (balsa) for doing my A test with, there's alot of different setup's

im still not sure what size servo's it use's

this is what iv come up with so far

4x corona 939mg (mini)

d3548 turnigy/5 900kv outrunner

3s 2200

Kontronik-JAZZ 40-6-18

will this be ok

thank you Alan for reply let's hope lots of good weather

Andy

 

Edited By confucius on 18/02/2012 19:47:00

[Alan Randall]

Hi Andy,

I have used 4 of these from BRC, though I think Cod do them as well -

http://www.brchobbies.co.uk/?page=shop&action=additem&item=809

They are Tower Pro MG 16 R. srvos. which fit exactly. They were doing a discount price for 4 when I bought them which made the total package inc postage cheaper than GC.

Alan

[confucius]

Thank you Alan,

i'll have a look and see what i can find as they are just a bit bigger

[Alan Randall]

Andy,

The motor you propose is probably just a different branded version of the one I am using with a higher Kv. 4Max, Giant Cod Turnigy and others often sell the same motors unter their own brands.

Alan