Alfa Model Focke-Wulf Ta 183 Huckebein

[Jimbo 0]

I posted a week or so ago that I had acquired one of these models.

 

As most of you know, electric isnt my preferred power source, nor are models of this type generally, so I will probably need some advice as I go along from the likes of Jaques and Andre who fly these things a lot.

 

So far I have the following bits:

 

Hyperion HP-Y22S-4200 motor and 3 blade fan (that came with it).

An Arrowind 25A ESC with BEC.

3x Hitec HS55 servos (2 for ailerons & reflex and 1 for elevator).

A tube of UHU POR.

 

I'll be running it on 2.4.

 

I've read a huge thread on this interesting aeroplane and apparently its a real bugger to launch, so that's something to look forward too

[Nutz 0]

Looking forward in seeing it going, maybe I should build another depron F-15

[Jimbo 0]

Naaa get something more of the same era - maybe an ME262 or a Komet?

[Gerard 10]

Sound like you need a launch cradle and bungee Jim.

 

Rich has a good launch system which I'm sure a modeller of your ingenuity could copy fairly easily.

 

[Bravedan 106]

From what I know about Alpha model construction materials, a Bungee made from more than one dropped P.O. band would rip it apart.

 

Jimbo, doubt you'll have any really major issues in flying it. The range were all heavily promoted and reviewed a while back and a lot of relatively inexperienced over ambitious parkflyers bought - most of those have trouble launching a Parkzone Radian let alone an EDF!!

 

My favourite EDF story -

 

Guy turns up in Norman Park with a home made EDF. It's a FW Slipstream chevron wing, a highly respected and well sorted product that unpowered is often used as a DS high speed low altitude glider "trainer". He had "tried for ages but could not get it flying, the instructions are rubbish and it's no good at all as designed", he said, so he modified it a little!!!. It now had a pipe insulation foam tube Fus, and a balsa/EPP T tail with twin GWS EDF. If you squinted from a mile away on a dark night it would have looked a bit VC10alike.

 

The Pipe Insulation had no reinforcing, so the tail to main wing incidence was, how can I out this politely, somewhat variable, as of course was the thrust line. All the gear was taped on externally. It still had the flying wing elevons, the tail was just to "stabilise" it

 

Mate and I failed dismally trying to politely get him to abort, as there were a lot of dog walkers around, but he straps on a relatively large battery right on the nose (for the two brushed fans), winds up the fans and throws it near 60 degrees up.............. It's SO flexible that it has a high degree of "self trimming", the near vertical launch only causes the Fus to sag even more, and it levels off..........briefly.

 

What ensued cannot be called "flight", with it switchbacking violently while skidding turns like a drift car as he furiously banged the sticks anywhere at all to no real effect, it piling in 50 feet away, fans screaming but providing no perceived forward thrust. Now, this is where you realise just how infuriatingly survivable EPP can be, as several further tries ended up the same way !!!

 

Undeterred, he stayed all the time we were there, and by the end managed one truly terrifying "circuit", but fly it did, and he did land it in the same county, relatively unbroken.

 

And you still think YOU need help?????

[Gerard 10]

Lol!!

 

Did you surreptitiously pin a large KEEP CLEAR warning notice to this guy's back Dave?

 

 

 

 

 

Sent from my iPhone using Tapatalk

[Jimbo 0]

Right so first questions on the Alfa build for you electric heads...

 

The elevator and Aileron push rods are thinner than thin things on a diet. They have a 90' bend at the surface end, and nothing at the servo end.

 

Assuming that the bend goes into the horn on the surface, 2 questions:

1, how do I stop it coming out the hole? Its just a bend in the wire at the moment. Heat-shrink or something?

2, what do I use on such small wire to connect to the servo horn and be able to make adjustment. Can I use teeny tiny turrets, and if so, where to get them from?

 

I've used magnets to hold the 2 fus. halves together instead of gluing. Is this strong enough? Rob Newman says yes but I'm not so sure...

[Bravedan 106]

My usual method is to "Z" bend the surface horn end. At the servo end I use the aluminium micro rotating ones where you push the wire through to the right adjustment and then screw fix it, and it's held to the servo arm by a grmmet or a screw.

 

Dubro sell VERY small ones, GWS ones are larger.

 

I have both here if you need quickly, I'm ten mins from you...........ring me?

[Bravedan 106]

Re: the magnets, have never held a Fus together that way.............and not sure I would, but neoidium magnets are so strong that the depron will tear before they part unless something is slid in between carefully, so what Rob says should work...........depends on the type of magnet!!

[Bravedan 106]

For the record, in case anyone else needs, the very small Dubro EZ Connectors are these:-

 

http://www.sussex-model-centre.co.uk/shopexd.asp?id=4936

 

(They also do a larger type)

 

The GWS ones are bigger and can cope with bigger wire, the pack number being GWPHD002

[Jimbo 0]

Thanks to Dave for supplying me with 3 of the very small DuBro connectors this evening. I'm about to go and drill some servo horns

[Jimbo 0]

Well all the internals are done with the exception of fitting the Rx in place.

Spent some time adding the decals too. I'm pleased with how it looks.

 

Only jobs now are: fitting the Rx, joining the fuselage halves (going to just glue it I thnk) and balancing the fan.

So, electirc boys - do I really need to do that?

 

Heres a pic for ya'll

 

[Nutz 0]

I have not balanced anything on a time

[Bravedan 106]

You presumably have run it up, does it sound smooth or not ?

 

While you'd think, probably rightly, that balancing the fan would help at the high revs an EDF runs at, the difficulty is how to tell what and where it needs it, and how to do it without adding say drag and ending up worse off.

 

I have only had four EDF, have not balanced any of them, and if I have lost out as a result, it's not evident to me where, however, have a look here:-

 

 

Neat and relatively easy. The consensus seems to be to use either CA or Silicone as the "weight", doing it a little at a time.

 

People seem to find lots of need to ease blade to duct clearances under the extreme centrifugal loads the fan gets, and this will no doubt upset balance. I only had touching on one of the four installations, and it was so minimal I allowed it to wear in. (Yea, I know, Lazy git.......)

 

One thing I would advise, make REALLY sure the fan is attached well to the motor and test it a fair bit before sealing it in both for fan security or that bane of EDF, fan flexure causing impact with the duct. I had a fan loosen off despite being careful (I thought!), and had to cut a trap to get access in the right place to refix it.

[Bravedan 106]

PS, that's the wrong camo for that rug...................

[Jimbo 0]

Cheers Dave, I'll watch the video and look at taking some preventative steps.

I have run it - it just sounds loud and windy to me - nothing to compare it to.

 

Re the camoflage, I had to put the rug under it or you'd not have been able to see it in the photo!

[Nutz 0]

An EDF is an mass air moving device so it will be loud and windy but are there any vibrations???????

[Jimbo 0]

Its quite hard to determine a vibration at the kind of speeds (frequency) that this fan will be spinning by ear or feel I think.

The motor is rated at 4200 rpm/v. On a 3cell pack thats 11.1v = 46620 rpm. This would terefore be an out of balance oscillation of 46.62 Khz.

 

I dont know if you'd feel or hear that over the normal niose of the motor at full wack - perhaps I need to do it a low throttle.

 

I am going to pull the aft Rx through the tail as far as it will go away from the motor/esc, but this does mean that it wont be mechanically fixed in place - will this matter? It'll be squeezed between the sides of the tail boom, and will have both inertia and all the servo cables to stop it moving forward again. Dya think this is OK? I could use velcro or something, but this will result in it being closer to the motor. Its a brushless and 2.4 if that helps.

 

Dave - I have some dubro connectors for you!

 

Jim

[Darren 0]

I am going to pull the aft Rx through the tail as far as it will go away from the motor/esc, but this does mean that it wont be mechanically fixed in place - will this matter? It'll be squeezed between the sides of the tail boom, and will have both inertia and all the servo cables to stop it moving forward again. Dya think this is OK? I could use velcro or something, but this will result in it being closer to the motor. Its a brushless and 2.4 if that helps.

 

Dab of hot glue? Double sided foam sticky pad?

[Bravedan 106]

Where will it be relative to the airflow (which I assume has a enclosing tapering duct from Fan to outlet hole).

 

I'd try to get it under a form of suspension. The wiring is OK to assist with that but obviously keep any tension off the connections. Nest it in a tripod of balsa strip?

 

As you probably well know, 2.4 Rx's should not be foam encased, they need air for cooling.

 

Twin aerials? At 90 degrees? Away from wiring, carbon/wire rodding? (as well as away from ESC and Motor).

 

In my Alpha Jet I placed the Rx at the very rear under the duct. I used extensions to get there.

 

The Bede has it mid mounted well under the fan unit as it has a deep body.

 

I try to use a UBEC for RC gear supply on high current installations with an OPTO ESC and this helps the RF interference situation as the UBEC can be more easily ferruled and remote located. The BEDE is on 6S supply, but then it is a fair bit bigger (though probably no faster!!)

[Bravedan 106]

Sorry Darren, but Hot Glue near Alpha's moulded Depron is a wee bit risky!!

[alan 0]

Jim,

if you're not sure about wether the fan is vibrating or not, don't worry about it.

All,

the Kv of an electric motor is theoretical and only applies with no load, so with a prop or fan attached it will always go slower, how much slower depends on how much load.

[Jimbo 0]

Under the duct is no good as there's no access there. The instructions call for it either behind the rear elevator servo (which is where I have it) or in front, but that is over the motor.

There are 2 servos up front which both have to run directly past the ESC - not ideal, but what can one do

 

I pulled the Rx aftwards with some cotton, up into the tail section and there is stays.

Impossible to get it fixed in there without using excessively long servo extensions which I didnt want to do.

 

It blows a lot of air, so as Alan advises, I've stopped worrying

 

Well, its all together now, so tough luck if it has problems. I'll bring it up Thursday for a test flight in the hall

[Bravedan 106]

Great, Combat!.....I'll warm up the FireFly....................

[Gerard 10]

Look forward to seeing it Jim!