Acro Wot ARTF (balsa) chat

[Daniel Cardona]

Posted by Danny Fenton on 15/09/2016 18:39:18:
Hi Geoff you miss my point this is an electric version but the parts supplied wont work.
Sure i can convert a model to electric, but the hatch they have already cut is underneath. All the strength is in the top, so you cannot put a hatch there without re instating the strength underneath. An artf designed for electric should not need redesigning to work imo
Cheers
Danny

If you want something to your standard, you have to build it yourself. That's I always wanted the Kit and eventually I bought that. I don't regret it because it was a very fun and easy to build aircraft and I believe if covered with traditional film it will even be lighter than the ARTF. I think it's also a good kit to convert it to Electric.

Mine is powered by a Laser 80 attached to the stock liteply sandwiched with 1.5mm Aircraft grade Ply front firewall. Chris Foss powered his with a laser 75 and he didn't changed the design in all these years so why bother? I only add the recommended 1.5mm balsa reinforcing on the fuselage sides and fiberglass cloth on the undercarriage Area. 6lbs ready to fly covered in tissue and dope including the wings.

Daniel

[Tim Flyer]

Here is my Acrowot powered by an OS FS80 alpha. I replaced the kit firewall with decent ply and lined the front section with 1/16th ply . It is epoxy glassed all over and very strong. It flies very well in all weathers. It is way way stronger than the ARTF version and easy to repair . LA great design from MrFoss. 😊.

[Phil 9]

can anyone tell me what size the ripmax fuel tack is for the artf acro wot

[Richard Wills 2]

It's 270cc, but it doesn't fit! it's too short to reach the bulkhead it is supposed to sit in. I slipped a 22mm copper pipe joiner over the neck and enlarged the hole in the bulkhead slightly to fit it, this spaced it back a bit.

I'd have no problem using the Hitecs, other than I hate them, but spec wise be fine.  Don't worry about the speed, they only move as fast as you twiddle the sticks.

Great model, flies amazingly. I have an OS 50 SX in mine, with 3001 futaba servos all round. Neither wants nor needs anything stronger or faster servo wise. Agree covering is rubbish, though does it really matter, went over with a really hot iron and it looks reasonable now.

Edited By Richard Wills 2 on 04/12/2016 18:07:11

[Phil 9]

many thanks Richard. It does fly well and is very easy to land

[Richard Wills 2]

Did you use the 225's in the end?

[Phil 9]

Posted by Richard Wills 2 on 04/12/2016 18:39:04:

Did you use the 225's in the end?

yes and they seem to be ok so far

[Jonathan M]

Well, I've been blundering through the assembly of my Acro Wot, my first IC and non-BNF 'build' - including a careless dribble of thin CA right down onto the canopy!

Used Gold-N-Rod snakes for the elevator, which necessitated boring a 25mm access hole in the underside of the rear fuselage so I could bind the sheath to a former at its mid-point to reduce flex. Stuck with the closed-loop supplied for the rudder but crossed the wires. Managed just enough clearance between servo-horns, but only by alternating the suggested orientation of each of the servos in the manual.

Other 'interventions' included drilling a hole through the plastic motor-mount to accommodate the ASP 70 FS choke extension lever. Yet to hack away at the cowling to clear the cylinder head, exhaust and other protrusions.

Battery is a 4.8v 3800mAh pack which will go under the tank in the forward bay - heavy enough to overcome any as-yet-unknown inherent tail-heaviness in the structure, especially as laziness overcame me and I installed the servos in the cut-out bay provided aft of the wing CG instead of constructing a more forward mount. Using Futaba S3003 servos throughout, hope the 4.8v supply will provide enough torque.

Sloshed fuel-proofer as liberally as possible into the forward bay behind the engine bulkhead, as well as forward of it and down the nose exterior. Tank is a 10oz unit, which is a half-inch too short to be held in the cutout supplied - can I just glue in an internal support, or should it have some foam go-between to avoid foaming?

Also, I'm proceeding on the assumption that I should equal the radius of the servo arm to that at the control surface - is this the correct way to proceed as a starting point before using the TX to fine-tune things?

Sorry to ask daft questions, I'm just more used to building rubber and CO2 powered indoor 20" span scale and peanut scale jobs.

[Steve Hargreaves - Moderator]

If you leave the canopy in water over night the CA might come off. Otherwise acetone will shift it. Try the acetone on a corner first to make sure it doesn't melt the canopy...a CA dribble will look better than a hole.....

Choke for the ASP70....don't bother...remove it from the engine & throw it away.....you just don't need it. APC13x6 prop works very well on this engine

Yes tank is a pain....I glued some 1/2" balsa blocks to the "inside" of the former & then sanded them back using the Dremel so the tank fitted snugly & was well supported.

Keep the servo arms at 90 degrees to the pushrod.....& as close in to the centre as reasonable for max torque. Equal lengths of horns is nice to have but not essential. Get everything as close to perfect as you can mechanically & then fine tune with the Tx......

The AW is a great flyer.....enjoy

[Jonathan M]

Thanks for this Steve.

If weather calms down, and the job gets completed, then a club mate will help me with the maiden flight this very Sunday!

Jon

[Bill_B]

Hi Jonathan, I can't understand why you had to change the orientation of the servos from what the manual suggests as mine fitted correctly without issue (see photo). Having said that, I did find that it was better to cross over the rudder cable as you did. With reference to the elevator pushrod, I found that the supplied unit fits and operates perfectly. I know mine is electric powered, but that shouldn't make any difference to the issues you've mentioned.

For anyone that's thinking of going the electric route, you may find that the supplied battery tray isn't of much use for a 6s set up (5s is recommended in the manual), and that you will most likely need to manufacture your own tray as I did. Also, as I elected to use an Eflite Power 60, the supplied stand offs were too long so I fitted my own adjustable units to achieve the correct spinner clearance . The AUW of my particular Acrowot with a 6s 4000mAh battery is 2.98 Kg (6.5Lbs) and has unlimited vertical performance using a Graupner G-Sonic 13" x 8" prop and an aerobatic flight duration of 5-7 mins, dependant on throttle use.

 

 

 

 

Edited By Bill_B on 07/12/2016 10:12:20

Edited By Bill_B on 07/12/2016 10:14:47

[Jonathan M]

Bill, my setup is the same as your's except that, being IC, I have a third servo for the throttle in the tray.  As you can see there's no way either of the side servo arms would clear the middle rudder servo's arms if they were oriented the same.

The ASP 70 FS is now more-or-less run-in and mounted in the airframe. Securing the battery and then the 10oz fuel tank in the forward bay was a major pain. As for the underside cutout for the exhaust, this simply doesn't fit. At one stage I almost considered cutting a bottom opening almost the whole size of the planking and making a screw-back-on cover. At another stage I resolved to only build from proper kits..!

I dislike being inexperienced and inadequately-skilled and making a hash of things, but I dislike poorly-conceived designs even more! Ripmax should really produce two versions, one for electric and one for IC, rather than this falling-between-two-stools compromise. Rant over.

All that's left is to mount the RX and battery-switch, check the CG and programme travels etc.

Sunday weather forecast currently looking quite nice...

Edited By Jonathan M on 09/12/2016 17:55:40

Edited By Jonathan M on 09/12/2016 17:57:31

[Stuart Z]

 

Hi

I have almost finished setting up my ARTF and have seen some of the challenges. I used a shorter rudder servo arm, you don't need the longer arm. There looks like interference in the above picture.  I found the need to put some serious support in for the throttle snake as I didn't want the snake flexing in the space. Ah the challenges! The cowl is my current challenge, I have an OS55AX to fit in. Not really carved a hole in F/glass before so it's a case of what tool to do the job? Hey ho, I'm sure it will be fun in the end!

It's a challenge but it's fun! All these things are part of the build challenge, ARTF or otherwise. But, years of working on kits and the like and you find your way through.

S

Edited By Stuart Z on 09/12/2016 18:46:21

[Keith Berriman]

Hi Jonathan On my build I actually glued ply spacer pieces under the  centre servo lug fitting area to lift the servo arm higher than the side two

Edited By RC Plane Flyer on 09/12/2016 18:56:54

[Jonathan M]

Good advice guys, cheers.

You're right Stuart, of course the fun bit is precisely the challenge of solving problems. Its all a question of expectations, and I would in fact have bought the kit to build from the ground up if I had the time, but self-employment and single-parenting can be very distracting! My usual evening activity is building rubber and CO2 indoor scale stuff, and I've encountered similar challenges with some kits - e.g. laser-cut ribs coming out 15% oversize, etc - so I've come to prefer building from plans and well-tested kits.

In the meantime, here are some piccies of how I came to solve the problem of running and securing a snake for the elevator and running the rudder cable-wires down the fuselage rear. Lots of holes to cover with black disks and rectangular pieces of film - which should at least match the larger black disks I intend to put on the underside of the wings for in-sky orientation!

Jon

[Stuart Z]

Jon

That snake's not going anywhere!

Anyone know what the covering is (thinking patching / repairs here)

S

[Former Member]

[This posting has been removed]

[Engine Doctor]

Be sure to cover the holes in the bottom of the fuselage to stop oil from getting in. 

[Jonathan M]

Good tips, thanks Percy (and RCPF). Shouldn't need longer screws if I epoxy the spacers on first.

Re covering the holes, do I need to do any surface preparation, or can I just paint Balsaloc on surrounding film areas and iron on black Solafilm?

[Former Member]

[This posting has been removed]

[Jonathan M]

Posted by Percy Verance on 09/12/2016 19:59:30:

And if I may offer some further advice Jonathan, I'd put a locking nut on the servo end of the elevator snake. That will eliminate any chance of the snake itself unscrewing with engine vibration and becoming disconnected.

Cheers Percy - no nut available, but a dribble of Loctite seems to have done the job.

Final weight (dry tank) came out at 6lb 4oz (2.85kg) including 50g of lead under the tail to bring the balance point to the specified 83mm from root LE. I was worried about the big 3800mAh 4.8v battery I installed in the tank bay (opposite side to the engine cylinder to redress that imbalance), but I did this as I'd read about people usually having to add much lead to the nose to counter inherent tail-heaviness. So, is this weight reasonable for a 70 FS powered version, or a bit too heavy really?

A question also on setting the throttle (as only ever flown electric so far): i.e how is 'throttle-cut' set up on an IC? Do I set the normal throttle travel to range from tick-over to fully-open, then programme a 'kill' switch to close the throttle completely? What about 'fail-safe'?

???

Edited By Jonathan M on 10/12/2016 23:30:11

[..]

Posted by Jonathan M on 10/12/2016 23:29:30:

A question also on setting the throttle (as only ever flown electric so far): i.e how is 'throttle-cut' set up on an IC? Do I set the normal throttle travel to range from tick-over to fully-open, then programme a 'kill' switch to close the throttle completely? What about 'fail-safe'?

???

Jonathan , Depending on what transmitter you are using the throttle cut is commonly in the sub programs on the TX. Basically you set up your servo ~ carb connection making sure you don't max out the servo travel and when a pre assigned switch is thrown the servo will jolt back and fully close the carb barrel thus stopping the engine.

[Former Member]

[This posting has been removed]

[Steve Hargreaves - Moderator]

Posted by Jonathan M on 10/12/2016 23:29:30:

A question also on setting the throttle (as only ever flown electric so far): i.e how is 'throttle-cut' set up on an IC? Do I set the normal throttle travel to range from tick-over to fully-open, then programme a 'kill' switch to close the throttle completely? What about 'fail-safe'?

???

Edited By Jonathan M on 10/12/2016 23:30:11

As Justin K says it depends on your Tx & what is available....in t'olden dayes we used to use the trim setting with trim fully forward for fast idle...mid point for slow idle & fully back for engine stop.....setting this up really DID test your modelling prowess.

Luckily things have moved on & on my Futaba set up I have stick fully back which gives me a fast idle for starting & general flying. Then I have a mix on my Tx that allows me to program a 3 position switch so I have position 1 (see above) position 2 allows for a slow idle for landing & position 3 cuts the engine altogether. Effectively all it's doing is moving the throttle servo slightly each time to close the throttle barrel a little bit more.

Failsafe is usually set via a button so you bring the controls to a set position & press a button (either on the Tx or Rx) & this saves those set positions. Where to set them is a matter for debate but personally I set ailerons to neutral, elevator slightly up, rudder slightly left & throttle to slow idle. Some will say cut the engine altogether which is fair enough but I like to have the chance to power up the engine once more if & when the "failsafe" is removed.

Another good tip (& this applies to electric models too) is to create a mix on another switch effectively mixing the throttle back into itself but in the opposite direction effectively disabling the throttle stick. If you engage this mix whilst carrying the model to the runway it prevents any accidental knocking of the throttle stick & the resultant increase in propeller rpm.

[Glenn Philbrick]

I have been given a shortened Acro fus ( one of club mates did a nose dive with it). I have repaired the damage and decided to try to electrify it as the top of the fus can be easily converted into a hatch for replacing the batteries. I am considering a Turnigy G60 motor running on 6S so I can use double 3S pack which I already have. I would like to run a 3 blade prop then maybe use the same motor set up in my Brian Taylor Mosquito. The motor is available in 300, 400 and 500kv, which is best?

Also I need to recover parts of the fus anybody know which covering is a match?

Thanksl.