AcroWot electrified.

[001]

I have just started building the excellent Chris Foss Acrowot. And I am electifying it. This is my second one, the first may still be flying around the skies near Valencia with a big two stroke Rossi! But I doubt it.

 

I already have the Motor, ESC and one 5000 5s battery, and am trying to decide how to make the access for the battery. I think that the large ESC and BEC will have to go inside the cowling.

 

I have found a build sequence, in pictures, on another site which shows that the builder has cut away the top of the fuselage in front of the canopy and inserts the Lipo from above. Which is Ok. but I would be concerned about the strength being compromised.

Entry from below seems to be out, mainly because of the position of the undercarriage and the need for structural integrity at that point..

Which leaves the possibility of joining the canopy to the fairing behind it and making the assembly into a hatch which can be romoved to slide the battery in forwards. The battery/ESC arming connection could be on the side of the nose, partly hidden by the 'vent' on the side of the cowling.

Before I do any more construction of the fuselage, has anyone experience of this.

Please, no comments about fitting a big four stroke.

 

[Tim Mackey]

The top hatch idea sounds best to me. Perhaps you could add single cross brace of CF rod or similar, which would still allow the pack to be inserted ?

[Richard Wood]

Richard,

My Galaxy Scorpion - which has a similar low wing configuration to

the Acrowot - has a top hatch cut out between the canopy & cowl

for LiPo access.(Pic in my album if interested)

Retention is by a magnet at the rear & a small dowel at the front.

It all seems very secure & there do not appear to be any structural

compromises.

Good luck with your conversion.

 

 

[001]

Tim, still thinking it over. Measuring and estimating.

Richard, thanks for your input. I see that you have a Sig Kobra. I have one in kit form which will be next in line to build after the Acrowot.

 

I am enjoying building from a kit again after a succession of ARTF's and foam models.

The only thing throwing me at the moment is having to work again in inches rather than millimetres!

[r6dan]

How come you aren`t just taking the wing off to replace the battery  as it isn`t too much faff? I have just finished my Acro Wot and it looks to me like it may comprise the strength of the fus by cutting a hatch,I could be wrong though!

[001]

R6Dan. The main reason is that I like to disarm the battery as soon as possible after landing, if flying on my own I do it on the runway.

Taking the wing off and having to disconnect the aileron servo(s) before disconnecting the battery seems to me to be adding unneccessary risk of an unwanted motor start.

[r6dan]

Ah...I see your point. Couldn`t you make the canopy removable (I know they are a bit floppy) and put a hatch under there? If you black it out you  could add some bracing  to stiffen it up a bit though.

[Danny Fenton]

Hi Richard you could use an arming circuit as I do on some of my larger models. In my case simply two 4mm gold connectors mounted in a small wooden block.

I would think it wise however, for LiPo use, to be able to extract the cells rapidly rapidly if something went wrong, removing the wing may not be rapid enough in some circumstances?

 

Can you post an overhead shot of the forward fus section so we can see the way it goes together?

 

Cheers

Danny

[001]

1) That was my first thought. I am considering buying a carbon fibre canopy, and making a base for it.  Or the front hatch as above.

2) Danny, I cannot show a picture yet as I have not got that far, still making up the fuselage sides.

 

I think it is possible to do it either way, it would help if the battery was slightly smaller, but it was being used in a model of a similar weight etc. which I have just sold, so I am allowing for that one plus some slightly smaller ones.......

 

 

[Mike Rolls]

I cut a hatch in the top. Made it just long enough to slide the pack in from above and in front. No problems. Like you, I like to disarm ASAP so the hatch is held by a self tapper into a piece of 1/8 ply glued to the firewall and arranged so that it only needs about 2 turns to remove.

Quite apart from the inconvenience of using the wing as the hatch, on the AW I don't see that it would be practical without compromising the strength of the U/C mounting. Similarly, locating the pack under the canopy would need a good bit of noseweight unless you have a VERY heavy motor.

HTH

Mike 

[001]

Thanks for the input Mike, what I intended was to remove the canopy and fairing behind it as a combined unit and slide the battery forwards, when I get the build a little further on,  I will know if I can do that and still have room for the servos. The AW now has cut-outs in the wing for 2 servos which gives more space above the wing. Thanks.

[r6dan]

When I built my Acro I lined the inside of the whole fus with light carbon/epoxy because I had it lying around and for that bit more strength,you could do something similar then you could cut a hatch out without worrying about comprising  the strength.

[Richard Wood]

Hi Richard,

Just a thought - electric conversions often need weight towards the

nose with the LiPo right up against F1.

If you access through the canopy area are you able to get it into place

& secure it easily? - fingers can sometimes get in the way - if you know

what I mean.

 

Many IC powered models have tank hatches & are fine with them.

perhaps the practice of coating the tank bay in epoxy increases the

strength here of course.

 

[001]

I have now nearly completed the model. The hatch is in the front. The ESC would not fit under the cowling (it is big and the wiring gets in the way) so goes next to the battery with the heatsink exposed. 2.4 receiver under the canopy which is painted black on the inside.

I tried dyeing the canopy with Dylon fabric dye, which has worked in the past, it didn't work this time, perhaps a different formula now.

 

 Now waiting for some decent weather.

[Stephen Grigg]

Nicely thought out job Richard

[Richard Wood]

Nicely done Richard.

No cooling issues to worry about with the ESC in that position

& it does look quite like scale exhaust louvers!

 

[001]

Just an update. Flew the AcroWot today for the first time, flew well, no trimming issues landed quite sedately.

 

I did buy a carbon fibre canopy for it, but had to leave it off because the 2.4 receiver/satellite had to go under it due to lack of room behind the battery.

Edited By Richard Bond on 19/01/2011 17:19:07

[Danny Fenton]

Excellent well done Richard. Is the canopy actually carbon fibre? I have had some stuff that looks like carbon fibre but is just normal Glass fibre. (Tx tray in this case, which obviously you don't want that blanking any signals).

Cheers

Danny

[001]

That was quick Danny!

The C/F canopy was genuine C/F I have now sold it on.

The canopy, now,is the original plastic item with a light spray of black acrylic inside. I can still see the receiver binding light through it.

[Danny Fenton]

yes probably wise. I have often thought of doing the acrowot, my leccy wot4 is still going strong. I have just taken the Rx pack out and fitted a UBEC the difference that slight weight loss is very dramatic, certainly surprised me. Model is more aerobatic and slower. C of G exactly the same, go figure......

Going to bring it to RCM&E fun fly?

Cheers

Danny

[001]

I haven't flownthis one enough to compare with my first AcroWot which originally had an Enya 50 helicopter engine , then a 0.91 four stroke. I last flew that about 12 years ago anyway. This seemed much easier to land, but perhaps that is just my flying.

Building.

The most difficult thing was to guess exactlywhere the lipo had to go, then adapt the construction of the fuselage as I went on.

I had to make the battery tray longer than it need be, so I could slide the battery back or forth,which is why there was no room for the receiver.I was surprised that the (large) ESC would not go under the cowling, a smaller one might. So it had to go beside the battery.

If I can get to the RCM&E fun fly I will bring it.

Picture taken today. The fuselage is covered in red Toughlon, which, strangely has a yellow cast on the side. Looks red to the eye. Somebody should market AcroWatt decals.

Edited By Richard Bond on 19/01/2011 17:58:27

[ken anderson.]

big well done from me richard....

ken anderson ne...1

[001]

Thank you Ken

[Richard Wood]

Well done Richard  - that Toughlon looks interesting stuff.

Are you building the SIG Kobra next? I flew mine a lot last year &

really enjoyed it.

Some of the balsa was a bit hard but despite that it was a nice

kit to build.

Goes well on 400W or so.

 

Edited By Richard Wood on 20/01/2011 08:36:49

[001]

Richard, no haven't started the Kobra. Toughlon is good stuff. Cheaper than Coverite, needs less heat (useful for covering some foam items) but not as goodto stick aroundsharp edges. (Right angles at wing seat etc.)