600 motor power output

[Andy Freeman]

Having not been flying very long and without having to go and buy the kit purely for experimentation purposes i was wondering.

 Does anyone know what sort of Wattage a 600 motor and 8 cell NiMh puts out. Assuming optimum prop selection. 

As discussed in an erlier thread i have a desire to play with a couple of  "old" designs that suggest this power train. Whilst I want to use the NiMh cells i would prefer to buy brushless motors/ESC.

One of the models is a 59 inch span cub (injected foam) and the other is more of 54 inch aerobat(ish) thing. both sugest the 600 motor plus 8 cell combo.

Many thanks in advance.

Andy 

[Erfolg]

I do not really know, but I guess less than 100w. Given the weight of a 600 motor it hardly seems worth using today.

You can buy a brushless outrunner for £20 that is significantly more powerful (Thumpers, Giant Cod). I even have a £5 outrunner that gives a similar power. Speed controller can be had for £10 or there abouts (Giant Cod)

Go Brushless, Better Go Lipo to.

Power, Power, power, power..............

Erfolg

[Guest]

I agree with erfolg.  - go with modern brushless and lipos - prices are still coming down and makes these worthwhile power systems

many moons ago I bought a geared graupner 600 complete with ESC on the back of it.  also bought 1700 nicads to go with it.  they are still in the cupboard as I checked out the weight of the lot and decided much too heavy for my kind of modelling ( anyone interested in buying them ?? )

the weight in your size cub would put wingloading way up

I can look up the instructions with my 600 to check power but I dont think it was very high. moreover, the wattage power input is not the power output as the old brushless were nowhere as near as efficient as the current brushless - about 50% or less i think for the 600

 John

[Tim Mackey]

QUOTE

"moreover, the wattage power input is not the power output as the old brushless were nowhere as near as efficient as the current brushless - about 50% or less i think for the 600"

And there's the rub

  Assuming 50% efficiency and an 8 cell nickel, thats only around 9V under load, and with a maximum current of say 20A ( which is still a bit heavy for a speed 600 ) thats only 180Watts in, and a measly 90 watts output !

Dump the lot and get modern Andy

[Andy Freeman]

Thanks all. Rest assured I have intentions on using a brushed motor. I was simply looking for a benchmark figure.

This actually asks more questions than it answer though. Am i to belive that, for example, the Aerojet 540 orNH Tucano are going to fly on 90 Watts or less?  Maybe I am missing something here!

[Guest]

I have checked the graupner spec on my geared 600 and the short time current is 22 Amps on 12 volts ( 10 cells ) which gives short term power of about 250 watts  I think I read somewhere that brushed efficiencies on ordinary motors ( no expensive exotic magnets ) was less than 50% compared to brushless at up to 90% if correctly matched to load.

the esc shuts down if on 20 amps for too long - graupner dont specify what they mean by "too long " from which we can infer it aint long !! so the 600 appears limited on load/time

 the weight of my 600 is 8 ozs incl built in 3:1 gear box and esc.  the 2000 nicads ( not 1700 as above ) would give neccessary amps but  weigh another 16 ozs - total power train now at 24 ozs.  I would not  recommend that for the size of models Andy is looking at. He mentions "old" and that suggests that technology at the time was 600 etc.  But I suspect that performance would not be great and certainly not like current systems/model combinations.

the modern brushless with lipo on 200/300 watts give a very lively performance on the size of model Andy is looking at but thats with the modern models with laser cut ply and almost no weight by comparison to the old types.

as indicated above, I consigned my unused 600 and the unchargesd nicads to posterity, waited till brushless / lipos came down in price to get more compatible systems for my kind of models

John

[Tim Mackey]

The difference with the models you mentioned are that they are geared, and also running higher cell count.However, even these will be FAR better with a modern brushless setup

[Chris Salomon]

And the other thing is, the brushed motor wears out the...................err.................brushes!  It's not long before you aren't even getting the optimum performance, whereas the brushless carries on merrily.  People used to re-set the brushes on the 600's after some use but why bother!

[Former Member]

[This posting has been removed]

[Andy Freeman]

No i really do not want to buy a brushed motor. I have never owned a brushed motor (except the one that came in the Easy Glider).

All i was looking for was a comparison. I am aware of the Watts per pound rule. I can have a good stab at working out what combination of motor, battery and ESC i will need to achieve that. What i had no idea is what a 600 motor would produce. Frankly, looking at some of the suggested outputs im suprised anything at all flew accepatably using one. You guys are preaching to the converted who was looking for a little information that google was unable to dig up.

Anyway, while you are on. someone point me to a budget, and i mean cheap, AXI 2820/10 equivalent

####Edit#### I now realise the typo in a previous post that has lead to this.Should have read" no intentions"

Don't i feel silly!

[Chris Salomon]

I think we all realised it was a typo Andy, we all just like slagging off brushed motors, that's all!

It is an interesting thread as many projects I have are based on the old technology and I have often wondered what powerplant to use.  All too often we hear of the i.c equivalents but never the brushed/brushless.

[Guest]

I  recently bought a scorpion motor and esc and am very happy with it.  They are much cheaper than axi gold , but I believe axi silver range has been introduced to compete with the lower cost motors. 400/600 watts on 3/4 lipos for about £65. altho lower cost I dont think the are budget type motors.

john

[Tim Mackey]

If you want real budget...then try the likes of giant cod - or even BRC hobbies, and of course if you dont mind H/K sourcing, then Hobbycity. I bought a stinking great 850 watt outrunner for the GBP equiv of around 21 quid.

[Erfolg]

Try the Overlander Thumpers, cheap as chips. Or Giant Cod Kedas, Tower-Pro all cheap.

I would put any one from these ranges, approx 200w, sub £20, against the best brushed 600

Erfolg

[nasa_steve]

andy

    in answer to the 45" tucano you pointed out will not fly reasonably on 90watts it weighs about 3lb minimum and i've not seen anything fly convincingly on 30watts per lb(the 30" tucano did fly on 90watts). yes the 45" flew but they struggled round on a direct drive brushed 600 and careful use of moving surfaces could just about keep em in the air. the aerojet was heavy and again struggled on a 540 can motor it was designed for. hence the excentric stigma that electric pilots got in the early days. hence the major use of the 28/20-10 axi in those days it was like the holy grail to electric flight(the tucano was awsome on them), like the advent of proportional control to the reed flyers i remember trying to justifying the near £150 price tag. oh how things have changed eh!!

nasa

[Andy Freeman]

So, i suppose the logical conclusion to this thread is for someone with a Wattmeter to do some testing.

It could then be made a "sticky" thread and the information would be there for all to see.

Might i suggeat a 600 can motor on 8 cells and ten cells. Also a 400 motor on 8 cells and is possible the ubiquitous AXI 2820/10 on 8 and 10 cells.

I think I wouls find it interesting to see what equivalents/minimum power train was needed by some of the old projects lying round in the garage.  

Its all very well stating something flies well on the AXI and 8 cells but surely a figure would be much better.  

[Tim Mackey]

Well that counts me out...havent had a brushed motor or nixx cell in my place for over 4 years !

I suspect that the AXI figures on nickel cells, is available on the model motors website. 

[Andy Freeman]

Well, Google might not be our friend in this instance. But this link might be

Look here

[Erfolg]

A watt meter will tell you what is going in, the important figure is what is being usefully used ie out put.

Or in engendering terms power (out/ power in)*100 = percentage efficiency

Another important value is the torque, as we all know that bigger dia propeller set ups are generally more efficient ( I am sure that the pedantic can quote an exception). Outrunners generally turn big props (relatively) efficiently.

Perhaps the most important aspect is the practical experience of electric modellers, who have come the brushed + nicad route to brushless +lipo. For the vast majority of us, the difference in performance is so great, that no further discussion is needed. Brushless and Lipo are Premier League, whereas brushed motors are possibly conference league. Conferance teams may beat the top clubs occasional, but hell will have frozen over in the mean time.

A simphathetic (owner of 6, now useless brushed motors and gearboxes, some new)

Erfolg

[Erfolg]

Whilst going to the tip, and rushing back(for me that is) for the Building Inspector".

I was musing on the 600 motor +gearbox issue and the efficency of motor that Timbo made reference to(50%).

Although many people are advocates of gearboxes, they only improve matters if a more efficient propeller can be used. Typically 30% efficeciency is often quoted for an average gearbox.

When we think about our 600 + gearbox set up, the figures are dismal. If 100w goes in, 50w is coming out, of that 50w, as little as 15w (30%)is at the output shaft. Compared with typically 85w for an outrunner(100w in). No need for gearbox, as it will turn a big (higher efficiency set up) prop.

No wonder most of us see the brushed motors as cherished memories of pioneering times.

Erfolg

[Guest]

Erfolg,

it was I that made reference to an estimate of 50%.

as you point out, brushless can turn a larger more efficient prop as does the geared brushed motor- which I understand was the prime purpose of the gearbox.

john

[Erfolg]

Sorry John,no insult or anything implied. I just forgot who said what.

With this type of discussion it is so easy to get hung up on the technicalities and assume that all start from the same point of assumptions/knowledge, which is not always the case. That you can feel compelled to state the obvious to many, but highly contentious for others

I just feel that in this case, you can change your assumed values by 20% or so and still reach the same conclusion.

This morning I was packing away my ic motors, as they are  now museum peices. A .049 Wasp, Cox black widow, PAW 1.49, AM25, 2 off ED Racers, Enya 20, Enya 25, 2 off Merco 35, OS 40, Merco 49, Profi 60. To those should be added my brushed motors and gearboxes as they are even more of a different age. 

Again apologies

Erfolg 

[Guest]

Erfolg,

I dont suppose you have an r/c throttle for the ed racers ?

 I saw them many moons ago and was daft enough not to buy at the time. regretted it ever since as the racer I have was given to me about 40 years ago and I have never run it.

 John

[Erfolg]

John

Neither of my ED Racer had a RC carburetor.

However I purchased one as an afer sales item. It comprised a nylon backplate and rotary valve. When fitted neither motor would run with the device. I later seperated the inlet duct with needle vlave from the backplate and attached this to the normal inlet duct/tube. the overall length was now considerable.

In this configuration it could be made to run at full throttle. On closing the barrel assembly the motor could be induced to run at a lower rev/min. But on opening the barrel, motor would normally die. The problem appeared to be that setting the top end fuel/air ratio was critical. It was also difficult to get consistancy.

The design of the carburetor was very simple by glow standards, not being possible to set the slow running air/fuel ratio seperatly from the top end settings. All in all not that great in my opinion.

May be there are others out there who now how to do it better than I did.

The other issue was that the cross sectional area of the motor went up dramatically when a silencer was fitted. The two exhaust ports, being the issue. I did consider options that would minimise the issue, but in the end decided that it was not worth the bother. The RC carb was never run with silencer.

My last ventures with diesel circa 20 years ago, on a 100" glider, were terminated when I found it to trouble some to obtain diesel fuel. Mixing my own proved trouble sum regarding ether and amyl nitrate, the chemist insisting that he mixed the concotion. It was not a roaring sucess either.

Erfolg 

[Guest]

Ok, Erfolg, thanks forr info.

I think most early attempts to throttle diesels needed a coupled baffle on the exhaust

John