Acro Wot too heavy at 3kg ?

[Andy-H]

I bought an old kit-built Acro Wot fus and wing at a bring & buy earlier in the year. I’ve recovered the wing with Oracover and it’s fine, roughly the same weight as  the Wot 4 mk3 I built years ago.

 

The fus however has been a bit more problematic. Seems to have been assembled with epoxy rather than wood glue and was finished with dope & tissue. I’ve simply covered with Oracover for simplicity and have converted to electric. 4S with an old Axi motor. It’s come out very heavy.

 

Having now set it all up and balanced with CoG at the most forward point recommended in the instructions (76mm from L.E.), it’s coming out at an overall weight of 3kg which is 0.5kg above the higher weight indicated in the instructions. This is with a 4S 3700 lipo right up front.

 

Question - is this too heavy to fly or will it still be manageable at that weight ? Context is that this is my first low wing and is for practice/experience. I have already made templates of all the main fus components and am inclined to build a new fus as one of my winter projects, with emphasis of keeping it light. 
 

Many thanks. 
 

 

[Graham Davies 3]

Hi Andy,

 

I had a similar story where I bought a separate fus and wing at a bring and buy in the 90s. I actually resurrected it a few years ago and it also was rather heavy. Mine had a 65FS up front. It will fly at 3Kgs on 4S, but might be a bit 'gentle'. As a first low winger, it will be fine, but be careful of slowing it down too much as the stall speed will be higher than if it were lighter. One thing you may find is that they tend to 'float on' on landing, so be prepared for a long approach, and as I said, watch out if you try to slow it down too much.

 

Good luck; keep us posted.

 

Graham

[Chris Walby]

IIRC mine with a Laser 70 in it and no lead came out at 2.7kg or even perhaps 3kg dry so I am sure you will be ok.

IMHO the problem is people stick over large engines and then need to add a load of tail weight and hence it comes out a porker. The consequence is that they land fast and people the complain about braking the UC, beef that up and make it even heavier...and so on.

 

I started off with the C of G forward, but soon moved towards the rear as I think its still conservative, but suites me!

 

PS for landing, don't try and put it down or a bounce will be induced followed by many more! 

Edited October 3, 2023 by Chris Walby

[Andy-H]

Hi Graham & Chris,

Many thanks, that’s very comforting. As long as it will fly and do a few basic manoeuvres, I’m happy. I didn’t pay much for it and I wanted to start out with something robust and inexpensive as a first low winger until I gain a bit of confidence. I’ll bear in mind comments about approach speed and bouncy landings. 
Cheers.

Andy

[Graham Davies 3]

I used mine as a 'warbird trainer'. I have loads of low winger hours, but wanted a model that I wasn't too invested in (so not frightened of!) that I could learn to fly in the correct manner. A heavy acrowot was ideal as it didn't bite as hard, but had many similar characteristics. As you've just described, I think you'll enjoy it. It will need a bit of thought to do aeros (just like a warbird), but they will look much more realistic than when a model is overpowered. And once you can land an AcroWot without bouncing, you can land anything!

[Andy-H]

Thanks Graham. That’s useful to know as that style of flying is what I’m hoping to work on. 

[Andy48]

20 hours ago, Chris Walby said:

IIRC mine with a Laser 70 in it and no lead came out at 2.7kg or even perhaps 3kg dry so I am sure you will be ok.

IMHO the problem is people stick over large engines and then need to add a load of tail weight and hence it comes out a porker. The consequence is that they land fast and people the complain about braking the UC, beef that up and make it even heavier...and so on.

 

I started off with the C of G forward, but soon moved towards the rear as I think its still conservative, but suites me!

 

PS for landing, don't try and put it down or a bounce will be induced followed by many more! 

My new electric Acro Wot was a pig to fly until I moved the CofG a good cm forward from recommended, loads of noseweight, 4000 5S battery as far forward as it would go, tail as light as possible.

[gangster]

That doesn’t sound too heavy, I have no idea what mine weighed but it must have been over 3k. Following a crash I rebuilt it , glass coated the fus and gave the lot a new coat of paint and tuffcote So that’s 4 coats on the wings. I also replaced the engine with a 2 stroke 61 balance was spot on. Flew it for years, flogged it and the new owner flew it for years So don’t panic I bet yours is lighter than mine was

[Chris Walby]

I have found with a number of models that fitting Laser engines produces a pleasant sound, reliable and no added weight in comparison with equivalent 2 stroke. Electric tends to be lighter, but then needs lead to get the C of G so you end up back where the IC boys started.

 

Better take mine out for a fly soon

 

[Andy Stephenson]

On 04/10/2023 at 18:00, Andy48 said:

My new electric Acro Wot was a pig to fly until I moved the CofG a good cm forward from recommended, loads of noseweight,...

That's odd, mine never flew better than with the CG 1/2 inch behind the most rearward point recommended. It was an original kit Acrowot so it may be different from the ARTF version.

[Andy-H]

Well, it flew ! First attempt was hairy to say the least,  courtesy of my probably flying too slowly and CoG being too far back (error on my part). Heavy landing but fortunately I managed to get it down in one piece. 
 

After adding healthy dose of extra lead in the nose to bring the CoG to the front of the recommended range, and keeping the air speed up, the second flight was delightful. 3rd flight was also successful until just after landing, the u/c gave up the ghost when it came to a halt. That first heavy landing to blame, methinks.  I’ll keep the CoG at front of recommended range whilst I get used to the model and will then slowly adjust to taste.

 

I confess though that I now have a clone fuselage build in progress. Construction as per original but with lighter wood where possible, white glue not epoxy and to be finished with some spare glosstex I have in the box, rather than Oracover over tissue & dope. I’m hoping that if I can keep the tail light, I’ll need less lead ballast up front and will be able save a fair bit on the overall weight.