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Member postings for Frank Skilbeck

Here is a list of all the postings Frank Skilbeck has made in our forums. Click on a thread name to jump to the thread.

Thread: Good Source of Electric Motors Anyone?
19/07/2008 20:32:00
Hobbycity if you don't mind buying from Hong Kong, I bought a Turnigy motor and its very good and excellent value.
Thread: Which battery type?
18/07/2008 20:55:00

Watch some of the higher capacity AA cells, I have a pack of 2400 mah AA cells (4.8v) and the voltage drops right off if I try to pull more than 0.5amps from it. If I cycle it a few times it seems to improve but then will revert to what it was. Note these are not the newer instant type cells.

The GP NimH cells (AA & Sub C) seem very good in this respect.  

Thread: Help !!!!!!
16/07/2008 13:16:00

Not really it would depend on the diameter of the fan, if its only 50-60 mm then it will be a smaller diameter than the prop, I have a couple of small EDF's around 50mm using 4,000 kv motors and they pull around 20 amps.

a 1350 mah battery is very small for this application hence it's getting very hot and probably cutting out after a min due to the LVC cutting in.

Just for interest I ran a 3200 kv motor with a 4.5 x 3 GWS prop in the Drive Calc simulator and on a 3s set up it predicted it would pull 20 amps, so I would say that it's the battery which can't deliver the amps. Not sure why your ESC failed though. Note an APC 4.5 x 4.1 prop increases the current draw to 25 amps, so it would be good if you knew what the prop is as a small differnce in size can give a big difference in the amps drawn.

Thread: Help with the EE Lightning
12/07/2008 21:51:00
what about this one as mentioned in RCME August issue Fly Electric column.
Thread: bear with me...
12/07/2008 18:51:00

or aren't, in fact....

That's surprising I thought there would be a good demand for these. Don't forget you might need to add some nose weight to your twin star, I'm using a 3250 mah 3S and needed some extra nose weight. 

12/07/2008 18:28:00

The reason the 400's struggle on a 3s lipo is that the volts are typically higher than a good old 6 or even 8 cell Nicad, so the 400 will spin a lot faster, the power drawn on a given prop is roughly the square of the speed, i.e. twice the speed 4 x the power, so if you doubled the voltage then the amps would also double.

If you put a smaller prop on then the motor will still spin faster but need less power to spin the prop at this speed so the amps will come down.

Beware of reducing the WOT setting in the travel adjust on the Tx, some ESC's autosense where full throttle is so dialing it down this way might result in the ESC setting 100% when throttle is at 40%.

You'd be far better just throttling back when in flight, you then have the option of overpower for brief durations if required.

I've got a twinstar running on the original 400's with a 3s lipo and use full power for take off on the UC I've fitted and then throttle back. The motors may burn out eventually and then I'll replace them with some the new brushed lipo specific 400's that Puffin Models are stocking.

 One thing to watch if you are running the Grunther push on props is that the extra power can cause them to come loose and fly off , I had to put some proper prop adaptors on mine.

Next I'm off to try my Twin Jet on 3s on it's 480 motors, should be fun. 

Thread: New radios...
12/07/2008 16:45:00

Nice sets, but why have the display under the neck strap which makes it more difficult to read. Also it looks like the neck strap is positioned for a long 35 aerial to balance not the short 2.4 aerial. The Spektrum DX6i addressed this by putting the neck strap clip below the on off switch surely this wouldn't have been too difficult on these top end sets.

Maybe the futaba still has the 35 aerial so you can get the set to balance

Thread: Where have my watts gone?- advice please
11/07/2008 18:41:00
OK I wasn't sure why you were disconnecting the red wire if you though the ESC didn't have a BEC. I agree it's probably best to use a separate Rx battery  than a regular BEC, the new ESC I've just got uses a switching BEC which can drive a full compliment of servo's.
Thread: A little competition for forum users
11/07/2008 17:17:00
My turn please
Thread: LiPo's How Long Do Yours Last?
11/07/2008 17:15:00

Coming out red hot is probably part of the answer. I haven't measured how many cycles i get out of my cells, but I put a 1400 mah 3s in a plane which normally used a 1800 mah 3s (both 12c I think) and the 1400mah was ruined pretty quick.

I'm running some 1500 mah cells (3s) in my EDF but it's only about 200w and the cells come out warm not hot, I have not noticed any significant deterioration to date but I'm probably only running them at 12C or less. 

Thread: Where have my watts gone?- advice please
11/07/2008 11:41:00

Timbo, I've just got a Turnigy 60A ESC with a built in SBEC rated for 3A continuous, 5A peek. I think Turnigy and Tower Pro are just rebadged versions of the same.

If i understand Dave correctly he might have an ESC with BEC and has disconnected this to use a separate battery. The problem with then using the programming card is that the BEC probably provides the power to the control electonics in the ESC and programming card, with an OPTO ESC the power for the control electronics probably comes from the Rx battery. So if the red wire is disconnected then there is no power from the BEC to the programming card.

Dave I didn't understand your comment about the other servos and Rx when you were using the programming card, to program my ESC I have to unplug it from the Rx and plug it into the programming card.

Thread: Help !!!!!!
10/07/2008 23:10:00
A 3200 kv motor is a very high rpm motor for use with a prop unless used with a gearbox. What size prop was supplied.
Thread: Where have my watts gone?- advice please
10/07/2008 23:07:00

Dave, just a thought your ESC has a BEC and will use the BEC to power the programming card when you connect it to the ESC, if you've disconnected the red wire then it won't  power the programming card. I have a Turnigy one which I think is the same as the Tower pro type and it does have provision a separate power supply if you are using an Opto ESC.

But maybe to program the ESC with BEC the ESC has to power the programming card, have you tried reconnecting the red wire when you are using the programming card. Note as Timbo says though the lipo setting won't affect the max power sent to the motor just the low voltage cut off  point.

10/07/2008 17:33:00

To get 700 watts from a 4s battery you will be pulling over 47 amps, thats about 13c on your existing battery so shouldn't be a problem. But you would only get 4.6 mins at wide open throttle so allowing for flying at less than full throttle you would need to set your timer for less than 7 mins.

I would think 2 x 3s batteries you mention above would be a better way to go with this plane, 700 watts on a 6s is going to be around 32 amps which is kinder on your batteries and gives a decent flight time, well over 10 mins.

 I've got one of these

Gives 8900 rpm on a 13 x 6 at 36 amps on a 4s battery, about 550 watts, you could probably put a slightly larger prop on it and draw a bit more current.

10/07/2008 12:15:00

I ran a 370kv motor through drive calc using a 16 x 10 prop and it gave these results

4S - 23A, 4700 rpm, 2029g static thrust

6S - 45A, 6550 rpm, 3949g static thrust 

So looks like you need a 6S battery (or 2 x 3S in series) and your ESC would be fine.

Note I substiuted your  motor for a similar one as the Thumper motor was not in the data base. If you went to 8S you might have to prop down, say 16 x 8

Thread: Plugs n' Batteries
10/07/2008 08:46:00

I think the fleet plugs were pretty specific to fleet, I can't remember anybody else using them. The batteries in the TX are not on a plug but are soldered directly in, well they are on the two sets I've got.

Can't you reuse the leads off your existing RX battery. 

Thread: You guys aren't going to believe this!
09/07/2008 14:36:00
The "batteries" or ultra capacitors you describe might not be 30 years away,303,p1.html?a=f
Thread: Good park "hack"?
09/07/2008 14:21:00

If you are just a relative beginner the small park flyer low wing types might not be all that great as orientation can be a problem and they get small very quickly, probably best for after you've had one low wing plane under belt, and then I'd recommend one of the Alfa warbirds.

But for now you might want to consider something like a Multiplex Minimag

Thread: DX6i Tx battery
07/07/2008 22:43:00

"Incidentally I thought it remiss of Spektrum to go on and on about the charger plug polarity, but not mention that a std Tx charger is the wrong voltage!"

Good point but then again my 35 Tx is a Multiplex with a 6 cell battery so I never use a standard Tx charger

Thread: Methane shortage?
07/07/2008 14:29:00
I thnk people mean Nitromethane, methane is what British Gas send to your house for your heating system
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