Timbo, it's your fault

[winchweight]

Well maybe.

Because of my success with the Air Blaster and Timbo's damned enthusiasm for leccy stuff (as well as some very good tutorials), I've decided to resurrect my Foamy Jet depron Hawk.

For those that remember, it is powered by a 200w pusher setup from BRC (http://www.brchobbies.com/?page=shop&action=additem&item=39), but has suffered terribly from glitching. Originally it had a HiTec rx, then a Schulze 535, as of tonight it now has a spare GWS 8ch rx, that was lying around. Last time it flew it was erratic at best and had a bit of an arrival.

I haven't got to the bottom of the glitches, but the rx is as far as possible from the ESC (in the nose with the battery), the ESC is next to the motor, but I've yet to find a satisfactory route for the aerial.

I have checked it over and cannot reproduce any glitches on the bench. Even range checks are fine. So I have a new rx with a bigger & better battery pack. I ran it up tonight on my Watt Meter (new toy), without fresh charge on the battery, and got the following figures:

24.56A, 11.40v, 278W

The ampage is quite high given that the ESC is a 25A unit (although the manual says 30A). Do I need worry?

[Tim Mackey]

I am somewhat surprised that you are seeing the 3s ( I presume its one of the 1700s I sold you ? ) holding 11.40V under a 14C load - I usually only get around 10.5 as a norm. That said, I would think the ESC should be fine as the powertrain unloads in the air ( especially props more so than EDF ) and current draw will drop off a fair bit to that seen in static testing....I usually reckon on around 15 - 20% less, which puts it at about 21A. The controller is probably rated at 25A constant, and 30A for short bursts such as take off. I cant say I am too enthusuiastic about GWS receivers in the main, certainly against the rather excellent schulze 535. What may be slightly more worrying is the 270 odd watts you are pumping into what is only a 200 watt motor - and with a maximum recommended current draw of only 15 - 20 A

Your getting close to magic smoke time here.

One little fast EDF I have was only ever finally cured of some minor glitching by being converted to 2.4G - I tried pretty much everything else and failed.

You dont say what the final AUW is with the new battery... remember for good jet like performance you need at least 100 watt per pound. What battery and prop were you running on before, and what prop now?

Of course, all this is said with the usual disclaimer, and if it fails it is most certainly NOT my fault, however if she flys a treat, you know where to send the cheque

[winchweight]

LOL

The battery pack is a new Loong-Max 2250mah pack. The old battery was an unbranded eBay special: 2200mah and no balance plug.

The schulze rx is in my Blaster now and the GWS is all I have since my LHS is shut for holidays

As for the prop, I'll take it off and have a look. (Dull moment - I can use a convential e-prop as long as it faces the right way can't I? The motor is a pusher, so I assume that means it turns the opposite direction.) I don't have may props, but I might have a set of 7x5 APC-E props somewhere.

[Tim Mackey]

Still excellent voltage being held. Yes a conventional prop is fine, facing the right way. The "pusher" variant I presume refers to the mounting system, as any brushless motor can become a pusher by simply reversing any two cables to get it to revolve in the opposite direction. What about this issue of excessive wattage through the motor?

[winchweight]

I'll try re-propping, but I'm not sure I have anything that'll reduce the current load until next weekend. i'll try it today and see what figure come up.

[Tim Mackey]

You could always set the tr throttle travel to limit the maximum wattage temprarily if it gets excessive.

[winchweight]

True.

As an aside, having had trouble with my FlyCamOne, I picked up a Practika mini digital camera today at Tescos. It's key ring sized and has video and still functions. I though I'd give it a go, seeing as it's a tenner.

[winchweight]

Well, I have just change to a 7x5 APC-E prop and charged the battery up to full. The battery is reading 12.51v unladen. Running the new prop I got:

21A, 11.3v and 237w - far lower than running the Master Airscrew prop of the same size. So if the ampage reduces in flight due to unloading, then the wattage must also fall as I assume the voltage will stay more or less the same? So I am probably not over stressing the motor now either?

As for the aerial, how best to route it as it is hugely long?

[Tim Mackey]

Yep, the wattage will fall ( although its actually the current that kills anyway )

Long Aerial wire ?  - how quaint said the 2.4Ghz man

[Tim Mackey]

I used to run mine along the leading edge of the wing, around the tip, and back down near the trailing edge. Seemed to work OK on most half decent D/C receivers...but a gws - the jury is out, just dont cut it!

[winchweight]

 Foamy Jets reckon the GWS rx should be fine. We'll see tomorrow.

I'm thinking the wattage might be damaging the motor, it's a 200w motor.

[Doug Ireland]

This may be a dumb question, but what is the difference between an E-Prop and a "regular" one?

[winchweight]

I think the main thing is that E props are designed for leccy and mustn't be used on i/c models. They tend to be thinner and a lot lighter and won't stand up to the stresses of i/c flight.

[Tim Mackey]

Thats about it my new leccy expert !

PS I did warn you about the motor wattage earlier - however, it did state on the "specs" they had pushed it briefly to 240Watts - just use the throttle stick with some consideration, get some airflow over it, ( exposed motor aint it ? ) and it will be probably OK.

[winchweight]

Well, I'm just back in from the field. Sadly, it's the best day so far and I have to drive to RAF Valley...

The Blaster was on great form, but the Hawk........ well it wasn't. Sadly the glitching is still there. I have tried a selection of rx, and it appears to be the rx that is the problem. I got better ranges by orientating the model so the aerial pointed at the tx on range checks. But glitch, it did.

So, next I'll try another Schulze or perhaps a Multiplex IPD rx, wrapped in foil, with ferrite rings. Maybe that'll sort it?

[Tim Mackey]

best bet would be the mpx IPD  IMO If your passing ...call in for a cuppa ( message me for details if you want )

Cant you get some flying in at the base ? 

[winchweight]

Unfortunately I'm in the company car with collegues, so there's no chance of stopping, nor of carrying my modelling gear. I was taking the van, but it failed it's MOT and is in being sorted.

Maybe next weekend I'll get an IPD and have another go.

Cheers!

[Former Member]

[This posting has been removed]

[winchweight]

Helluva investment for a £25 foamy though!

[Mowerman]

My Piwakawaka with 200W motor.4 9g servos & Cirrus Rx glitched badly.

Partly cured by pointing the Tx ariel at 90degrees to the model.

[winchweight]

Hmm....  does this help when you're flying though. I haven't flown it since the last crash as it glitched very badly in the range check with the aerial down, at about 9m.

[Former Member]

[This posting has been removed]

[winchweight]

Looking!

[winchweight]

Not found....

[winchweight]

Still not found...

Anyway. I have rerouted the esc wire away from the servos, hopefully to cut down the interference. I have also ordered some ferrite rings to try and cut down the errant wigglies that way as well.

Might as well try wrapping the rx in foil, can't hurt. But I assume the foil mustn't touch the aerial?

I hope to pick up a Schulze rx this week, so maybe next weekend the flight will happen.

I am also expecting to collect a Ripmax Spit this week. Has anyone fitted retracts into it? Perhaps the servoless retracts from FoamyJet?

http://www.foamyjets.co.uk/index.php?act=viewProd&productId=64