Model / Motor match ?

[solentlife]

So here's the stats of the motor then model ... and I'm fairly certain paired they could be a good combo ... (prop size a little bigger than the 8x4 though ! I can live with pulling more amps as I have good packs) ...

data : >

RC Timer motor rated at :
Model No.: 2822-14
KV: 1200KV
Weight: 50g
Motor Dimensions: 28.7*31.5mm
Shaft Size: 3.17mm
Prop/Recom: 8x3.8/8x4
Battery: 2-3Li-Po
Idle current: 0.8A
Load current: 18A
Power (Watt): 300watt
ESC(A): 20A
Ri: 0.118
Pull (Approx): 950g



Model is :
Item number: RC8909
Trademark: Pilotage
Vendor’s item number: 5CH CESSNA(ARF)
Pilotage Skymaster EP Receiver Ready Airplane | Pilotage Brand | Partially Pre Assembled Model Airplane | Construction: EPP (type of
Styrofoam), Plywood, Fiberglass + Metal & Plastic assembly acessory| Set included Model airplane, pre installed servos, Brushless
Electric Motor, ESC - NO BATTERY, NO TX, NO RX, NO CHARGER| Made in china

--------------------------------------------------------------------------------
Technical parameters:
Length, mm: 980
Wing span, mm: 1210
Wing area, dm²: 22
Recommended takeoff weight, g: 980
Average wing loading, g/dm²: 44.5
Engine type: Brushless electric
Recommended engine: DT3007/xx;
Recommended battery: LiPo 3S
Recommended battery capacity, mAh: 1800

--------------------------------------------------------------------------------


I think it's the same model as Alishanmao has highlighted on Youtube ... as the advert shows lights and flaps etc.

It's a nice looking model and at approx. $100 for the ARF Rx ready package ... not so bad ..

I already have the motor as I bought it for another job that I haven't got round to building yet.

I would up the LiPo to 2800mAh to give me better capacity ... plane like that can surely carry the weight, I'd up prop to at least a 9" I think to get the diameter and a decent pitch of about 6 - 7 ... I know it's more than spec'd above - but when I ran it temp in my other model on 8 x 7 - it was fine.
I don't expect to do aerobatics ... it's a Cessna ... but nice flowing flight would be nice ............

So is motor acceptable ?

[Glacier Girl]

Hmm, don't know if I believe the motor specs.
300 watts divided by 18 amps is 16.666666

So to get 300 watts at 18 amp draw, it would need 16.67 volts. That's 4S power, and specs say 2 to 3S???

Anyhow, I ran the motor specs on MotoCalc. 3S with a 9x6.
16.7 amps, 24.0 oz thrust, and prop speed of 47 mph, so approx 40 mph airspeed.
Approx 109.5 watts.

So at best 50 watts per pound for your set up.

Basic trainer set up at best I'd say............

[CHELLIE]

Thats a big plane, that motor you have will never get it off the ground, that almost a 4 foot wing span, use this motor and a 9x5 prop with a 40 amp Turnigy 40 amp esc. for about a 1 to 1 power ratio. your 3 cell 2800mah lipo should be ok if its 20C rated or more, hope that helps, Chellie

http://www.hobbyking.com/hobbyking/s...idProduct=2140

http://www.hobbyking.com/hobbyking/s...idProduct=2165


A. Dame ( members like this guy) 1 thumbs up!Nice motor, runs pretty smoothly at medium timing, pulls 1050Gr (37oz) and 26A with an APC Thin 9X4.5E on a 3s LiPo.

5 star rating because this motor is defenatly worth the money.

[solentlife]

Originally Posted by Glacier Girl

Hmm, don't know if I believe the motor specs.
300 watts divided by 18 amps is 16.666666

So to get 300 watts at 18 amp draw, it would need 16.67 volts. That's 4S power, and specs say 2 to 3S???

Anyhow, I ran the motor specs on MotoCalc. 3S with a 9x6.
16.7 amps, 24.0 oz thrust, and prop speed of 47 mph, so approx 40 mph airspeed.
Approx 109.5 watts.

So at best 50 watts per pound for your set up.

Basic trainer set up at best I'd say............

OK - I own up !! My post was a little misleading .... sorry on purpose ... I needed confirmation of what I found .....

I too noted the mis-calculation in the specs when I first bought ... and is why I upped the ESC from 20A to 30A for a start !

I fitted the motor to my ME109 of approx 600gr and it was WOW out of sight .... but not so WOW as I thought it would be.
My present motor develops about 100W, is spec'd at 160W and actually with Wattmeter is reasonably truthful in it's advert. A turnigy motor.

This RC Timer - when I found it wasn't quite the Rise out of hand as I expected ... was put on Wattmeter and I got afluctuating max 120 - 130W reading on a 8x7 prop. I had a 30A ESC, 35C 2800mAH 3S LiPo connected all with good connectors. I was not amused !! On scales - it pulled 590gr thrust. (I suspend model from beam by tail, zero a digital scale - then open throttle ... weight then displayed is thrust ....)

I do have another motor that I'm looking at with a rep'd 2.5Kg thrust level ...

http://cgi.ebay.co.uk/ws/eBayISAPI.d...=STRK:MEWAX:IT

My reasoning is that if I assume ratings to be 2x what we get in practice - then I won't go far wrong.

Again I apologise for the subterfuge .... honest it was in a good cause !

AND I certainly will look at the motors suggested by you guys and dolls !

[CHELLIE]

that motor is way to Big that will RIP the wings off that plane thats a 4550-1000kv motor at 220g normally the 45 means outside can diameter, and the 50 means the length of the motor, here is a Turnigy motor that about equall to the motor you posted, 4250A, its equall to a 40 size glow engine at 195gr. The motor I linked to, the 3536B at 106g will fly your plane very very well, and you might want to add some extra 5 or 6mm carbon fiber rod or tube in the wing, with the motor i suggested, Hope that helps, Chellie


Model: TR42-50A
Max efficiency :38A
Max Load : 43A
Kv : 700
Power: 720W
Weight : 195gr
Pull/Thrust : 900~2100gr
Prop size: 11x5.5 or 12x8
Voltage Range: 9~15v
No Load Current : 3.4A
Shaft: 5mm
Resistance: 0.0327ohms
Max Efficiency: 82%
Power equivalent : .30 to .40 glow engine

WAY WAY TO BIG

[solentlife]

Originally Posted by CHELLIE

that motor is way to Big that will RIP the wings off that plane thats a 4550-1000kv motor at 220g normally the 45 means outside can diameter, and the 50 means the length of the motor, here is a Turnigy motor that about equall to the motor you posted, 4250A, its equall to a 40 size glow engine at 195gr. The motor I linked to, the 3536B at 106g will fly your plane very very well, and you might want to add some extra 5 or 6mm carbon fiber rod or tube in the wing, with the motor i suggested, Hope that helps, Chellie


Model: TR42-50A
Max efficiency :38A
Max Load : 43A
Kv : 700
Power: 720W
Weight : 195gr
Pull/Thrust : 900~2100gr
Prop size: 11x5.5 or 12x8
Voltage Range: 9~15v
No Load Current : 3.4A
Shaft: 5mm
Resistance: 0.0327ohms
Max Efficiency: 82%
Power equivalent : .30 to .40 glow engine

WAY WAY TO BIG

I realise the size and power possibilities with that engine ... but given the record of other over counter / online bought - over-optimistic specc'g .... I'm out on real values.

The pricing on the HK motor you linked to is VERY interesting and will most likely be the route I go ....

The 2.5kg motor was originally id'd for my Aerobatic ~1.5kg machine hanging over my desk ... a ply / balsa / built up job .... which needs high power to "try and rip it's wings off !!" .....



Wingspan : 1240cm (48.8 ins)
Length overall (not incl. motor mount / cowl) : 90cm ( 35.4 ins)
Wing chord not incl aileron : 26cm ( 10.2 ins)
Aileron chord : 7.5cm ( 2.95 ins)
Bare airframe weight before kitting out : 916 gr (32.3 oz / 2.02 lbs)

Given that I flew in the past a Wot4 Mk 1 designed for 40 size 2ST Glow - with a 61 piped Bluehead ST ... you now start to get the pitcture of my brutality when it comes to models !! I'm one of those who likes to throttle back and fly rather than push the motor near it's limits ...

The Cessna will most likely receive a wing mod anyway ... but first I want to see one before committing ... and being in the shop in Riga - next time I'm there - will sort ...

They do a package deal on the machine as well with motor etc. - will be interesting to see what they offer ..... compare figs with what I reckon / you lot advise ... and their deal.

I will let y'all know what happens ............

Nigel - you can always tell when I'm stuck not able to fly ... it's -10C out there ... light snow falling .... already about 1m of the stuff around .... lovely picture postcard stuff - but it's nice on a postcard !

[solentlife]

OK .... here's the motor they recc'd in the shop .....

Now forgive me for being a bit skeptical about this motor - but a) it doesn't look that powerful, b) the specs don't give a complete pitcture enough for me to arrive at good answer, c) look at price for what I believe is a marginal borderline motor for the model ....( 34.70 lvl = approx $67 )

Correct me please if I'm wrong ....

http://www.pilotage-rc.lv/catalogue/85_/85_20/RC5664/

I think I can do better than that .... WE can do better than that !!

Model price itself as it's over counter available immediately .... at 68.80 lvl = approx $134 .... is acceptable .... if all it needs is Rx and LiPo ...

[CHELLIE]

Originally Posted by solentlife

OK .... here's the motor they recc'd in the shop .....

Now forgive me for being a bit skeptical about this motor - but a) it doesn't look that powerful, b) the specs don't give a complete pitcture enough for me to arrive at good answer, c) look at price for what I believe is a marginal borderline motor for the model ....( 34.70 lvl = approx $67 )

Correct me please if I'm wrong ....

http://www.pilotage-rc.lv/catalogue/85_/85_20/RC5664/

I think I can do better than that .... WE can do better than that !!

Model price itself as it's over counter available immediately .... at 68.80 lvl = approx $134 .... is acceptable .... if all it needs is Rx and LiPo ...

Your right thats not a very powerful motor for your plane, the 3536B motor will do the job and be more than enough power, on the Wot4 Mk 1 designed for 40 size 2ST Glow , use this set up,

http://rcfoamfighters.com/blog/?cat=9

for under $90.00 USA and up to 146 MPH if you want to go fast with 1600 Watts

[solentlife]

So spoke to shop .... and they reckon the motor is already included .... so I went back to their advert .... DOH !! Silly me !!

Yep - when you space out the text better .... only parts missing are :

Tx
Rx
LiPo
Charger

The motor and ESC are already there. Now the problem is - is it the low power motor as advised or is it a more powerful job albeit cheap chinese line ?

So now I have to sort my model fund. I have a 50" span aerobatic Biplane Kit waiting in UK for me, that will need a 61 Glow or 15cc petrol up front .... plus now this Cessna....... I have to have my JR serviced and that will not be cheap .... ( I have an older JR 35Mhz that I keep for "serious models" ... believe me when I say there is nothing like it now ... not that I've found and be comfortable with ... )



Looks like a good summer coming up !!

[kyleservicetech]

Originally Posted by solentlife

RC Timer motor rated at :
Model No.: 2822-14
KV: 1200KV
Weight: 50g
Motor Dimensions: 28.7*31.5mm
Shaft Size: 3.17mm
Prop/Recom: 8x3.8/8x4
Battery: 2-3Li-Po
Idle current: 0.8A
Load current: 18A
Power (Watt): 300watt
ESC(A): 20A
Ri: 0.118
Pull (Approx): 950g

This motor weighs in at about two ounces, that would be 300 watts divided by two ounces or 150 watts per ounce of motor weight. IMHO, any motor running over 100 watts per ounce of motor weight might be pushing it a little.

I ran the motor numbers through www.motocalc.com (Free for 30 days, the $39.00). The motocalc result is running this motor at even 200 watts on three cells will likely burn it up. Predicted efficiency is only around 50% so one half of the battery energy is just making the motor hot.

Motocalc suggests that the maximum power this motor is rated for is something like 150 watts or so, which is about where this motor will run with the recommended 8-4 prop.

[solentlife]

Hi Kyle ... we already sorted this one out and as I said when I ran it on a model - it was pushing out about 120 - 130W on a 8x6 prop .... 3S pack.

Only problem I actually had with it was the LiPo didn't run long on it ... so is one the reasons I mod'd the model to carry a larger pack.
I then when I rec'd a replacement Turborix fitted that as model was before ...

The RC Timer is now spare and was reason I asked .. it is supposedly rated for a reasonable weight model - but as I found doubtful.

[kyleservicetech]

Originally Posted by solentlife

Hi Kyle ... we already sorted this one out and as I said when I ran it on a model - it was pushing out about 120 - 130W on a 8x6 prop .... 3S pack.

The RC Timer is now spare and was reason I asked .. it is supposedly rated for a reasonable weight model - but as I found doubtful.

Another motor in this class is the Hacker A30-28S, with 1140KV, 1.3 Amps no load, 0.068 ohms resistance, 2.5 ounces. (That winding resistance is 1/2 that of your RC Timer motor). Not cheap, but IMHO you get what you pay for. And they've got a service center in the USA.

Motocalc indicates this motor will turn an 8-6 prop at 9700 RPM on a good 3 cell lipo battery. Power is predicted to be 228 watts, pulling 21 amps out of the lipo. The A30 series Hacker motors have a number of different "copper windings" on the same frame, for use with different lipo or A123 packs.

I've got 7 of these Hackers ranging from an A30 to an A60-16M. All of them will run at their stated maximum power levels, and not overheat. My A30-12XL motor was run at 30-35 Amps on 4 Series A123 cells at full throttle during two flying seasons, with no problems. Still got that motor.

http://www.aero-model.com/Hacker-Brushless-A30-28S.aspx

Dennis V

[solentlife]

At present I'm stuck in NE Industrial China and far away from my models !

But I reckon that what I will do is buy the Cessna as boxed ... then give it my thrust test and see what the stock set-up gives.

I have various BL motors to fall back on if need be ... and appreciate links to recc'd replacements.

Let's hope it flies as good as looks ! I have a soft spot for Cessna's and also Cherokees ... the Cessna is a universally recognised airframe and IMHO is a nice looking design.

I want a model that is a bit more docile and forgiving than my ME109 ... this I hope fits that bill. I like the size also - not too big but big enough to have "presence" .....

I'll post a review once I get the machine .....