ELECTRIC SET UP

[chris hamilton]

hi, i have recently wanted to get into electric flying, i have brought a aircraft, RIPMAX reno racer, and a graupner 400 speed motor, i am just trying to figure out what battery to use, the motor is rated at 7.2v i think, the manual suggests a 9.6 volt battery (nicad) but they also say the motor is at 6v, it an old manual. any way i also have a 50amp esc to go with it, but a am not sure what battery to use lipo or nicads and what voltage etc to get. Any help is gratfully recieved

[David Ashby - Moderator]

You did well to get one of those Chris, I havn't seen one for years now. Graham had one and liked it a lot, it flew well. If I saw one I'd snap it up as they were a nice model.

It was designed in pre li-po days but a 2S pack with the brushed motor will do well but if you can upgrade the motor then she'll be superb with a 3S pack. Li-po's will keep the weight down too.

Best to get a programmable ESC with the brushed motor so you don't overdischarge the pack. The 50amp ESC you have is plenty sufficient ( a speed 400 will draw up to about 15 amps) but is it a brushed or brushless unit?

David.

[Alistair Taylor]

Chris

Good motor/esc/battery combinations for the Reno Racer would be;

1 - 6V Graupner speed 400 motor with 9.6V 800AR NiCads, or 500AR NiCads, or 1000MaH+ NiMH cells. You will need an 18 amp capable speed controller, and it would be a good idea to get a prop adaptor and carbon fibre gunther-lookalike prop. The motor will get hot and can melt the rubber sleeve used by the normal Gunther props.

2 - Bell brushless motor with 15 amp controller and 9.6V nicads/NiMH as above. Use a 7x5 prop and it will fly better than with the brushed setup, and for longer on the same cells.

3 - Bell brushless motor with controller and 2S lipos (I think - I don't use lipos). Make sure the cells can deliver the amps (at least 15 amps), and that the speed controller is set up for 2s lipos.

The 50 amp controller is overkill for the Reno racer (unless you're into flutter), and it's probably a bit on the heavy side.

A kontronik Rondo controller would be ideal for the Graupner Speed 400 motor, as it fits on the back of the motor and doesn't get in the way of the battery pack.

Don't fly it in a breeze like I did.....the fuselage is made from quite thin wood.

AlistairT

[chris hamilton]

Thanks for the help chaps, i have lobbed the 50amp and got a gws 400 one instead, i want to keep this whole venture cheep and nasty, just so can get a taste of electric, i love flying my nirto models, which i have done for some time, but get fed up with greasy clothes greasy car. I am going to keep the whole thing brushed at the moment only because of price. Plus the reno wont take anything else,other than a 400 without balsa bashing, which in time ill do with a brushless job. I have found its a bit of i minefield.

Is there any good books or info for rc electronic for numpties ???

[chris hamilton]

I figured it was old when i found it tucked away in the model shop, duster and slighty browned manual, however the rest was ok, and i got it a bit cheaper.

[David Ashby - Moderator]

Good find Chris, I'd snap it up if I found one.

Book wise, I'd say just keep reading the mag's. I've found the best way is just to get stuck in and the more electric models you build the greater the understanding. Trouble with books is that they date so quickly. The ezonemag.com is superb too.

[Alistair Taylor]

Good on yer for giving electric a try chris :o)

It does seem like you've taken something hallucinatory when you first venture into the area.

I've tried to keep it cheap and cheerful myself, and now some of the brushless stuff is starting to fall into this category.

I'd recommend the info available at;

http://www.cdmac.org/

These were written quite a while ago but are still spot on for the cheap and cheerful stuff.

Good luck with it


Alistair

[chris hamilton]

Thanks for that, one last puzzle or fear i have is the battery i have brought for the model, it's a 9.6v 800mah 8 cells, aa size cells that is. now i am not sure if the little reno racer with its 400 will shift these cell in the air, does anybody think the same or am i just being a bit sceptical and underestimating the performance of the 400 ?

and yes having purchased the 400 i noticed a ripmax brushless job for 22 quid with mounts etc, i know in the long run ill bash the balsa and make it brushless.

[Alistair Taylor]

If the cells are 800ARs it will be fine. Just practice your underarm launches (or get a proficient helper).

Once underway on this setup the RR should fly quite well, but, as you will have noticed, the prop on the front is not very big, and so it will need a "positive" launch (i.e. not like a javelin, but not like confetti either).

Don't expect it to climb after launch - keep it level/slightly nose up, and let the wing do the work. Once you have some height to play with - drop the nose and use the momentum provided by the battery pack to do fast strafing passes.

enjoy!

AlistairT

[chris hamilton]

i dont understand quite what a AR size battery is, the discription on the auction said aa size cells, whats the difference.?

[Alistair Taylor]

Oh - AR is slightly fatter than AA, and is capable of fast charge-discharge.

See the technofiles on this website where there is a good explanation of batteries for Speed 400 models;

http://www.cdmac.org

Bear in mind that there are NiMH cell packs now available at up to 1400MaH (or more!) capacity.

Alistair T

[chris hamilton]

well last night i connected every thing up and the thing burst into life, was very pleased. however later on i tried it again, but managed to short the spped controller by connecting the battery round the wrong way. oops after some time i work again but not quite right, as it wont shut down even with the stick in the lowest position. so thats a new speed controller needed luckily it a cheap one and new plugs, so i can put oppsite plugs on the battery and controller so i physically cant do it again. dope. same but hey ho. its a good learning curve.

[Alistair Taylor]

I fried my first speed controller and motor, bench testing them to see how long a battery pack would last - Doh!

Lesson learned - static amps are higher than flying amps, cos the prop unloads in flight....

At least mistakes are not too costly with speed 400 gear.


Alistair

[chris hamilton]

ah glad that was mentioned, i planned to do this my self.

Anyway its nearly all dont now so ill send a post when the test flights are compleate. just need a clear spot in the weather.

[chris hamilton]

wel i tested the beast last night at half 8 in my local park. With a hand full of amps and good lob she took off, and went about 30 feet before the wind got hold of here and pushed her towards the ground, luckly i had grabbed a handfull of up before hitting the deck, no damage other that a busted prop and my pride (as the people in the local rememberance hall had been watching.)

i would not have flown my nitro models in that wind, god knows what posesed me to fly the reno in 12-18 mph wind. DOPE anyway it was helpfull to know i need longer grass for the test flight untill i get it all trimmed up and rates etc sorted. However i think i may have bent the shaft on the motor, so ill have to replace that.

but mainly she is one tought little plane !!!!

[Alistair Taylor]

Hmmm - it's tough up to a point.

I started repairing the nose on mine last night after a similar decking in a breeze some months ago (been doing a lot of repairing recently).

The fuselage sides are a mix of soft and hard 1/16 balsa, with 1/16 ply formers. The strong-looking motor tray (1/16 liteply) does strengthen up the front end considerably, but if you go in hard you will have to practise your building skills to rebuild/reassemble.

Best of luck for the next flight

Alistair T

[CHARLES BROWN]

I have and use several elecric motors in models 480 and the good old speed 600 which comes complete with speed controller and a 2.9 gearbox, with these motors I use a 7 pack 2000 mah ni-cad pack, this pack weighs in at under 1lb which is an important consideration when it comes to electricaly powered models

[CHARLES BROWN]

re the elecric motor and battery question, I fly the junior 60 (ben buckle model)and the 7 cell battery pack gives me 14 minutes flight time but thats not flying flat out, and with a folding prop you get a nice slow landing speed (the dents dont show so much ) I fly other ben buckle types, as I think you just can not beat the vintage types for real stable flight at a nice reasonable slow speed, which gives more time to correct mistakes made by over using the sticks

[Alistair Taylor]

Charles

are you implying that the splintered remains of my Reno racer are the result of my over using the sticks?

:)

How perceptive of you....

I've invested in a plan of the Playboy Senior with a view to building it for the long summer evenings. The challenge will be fitting the one-piece 80" wing in the car.

I know what you mean about slow speed though. I gained a lot of confidence on a speed-400 powered vintage-style glider (Minidrake), that has paid off with improved (but not yet infallible) flying of faster/less stable types.

Chris - how are you faring with the RenoRacer?


AlistairT

[chris hamilton]

ah well to be honest, ah well it dosent fly, after the momentum of the hand launch goes thats it it just dives for the ground i have repaired it time after time, the motor isnt to hot know, but not sure why it dosent fly. sort of given up with it, but dont want to.

[Alistair Taylor]

Chris

I'm sending you encouragement vibes....Youcandoit...Youcandoit...Youcandoit.

I smashed two planes over the weeekend, one nitro, one elctric. it happens to all of us.

I'd failed to sort things out on both of them, like;

- C of G on the nitro plane - it was too far forward and the plane would hardly lift off.

- wrong prop on the nitro plane - it was an 8x6 and so the take off was hairy

- wrong glasses on the pilot, so I couldn't see enough detail to fly at distance and.....crump.

If the front end on the Reno Racer looks a bit mashed, don't panic. It's all made from 1/16 ply and 1/16 balsa. Cut back to good wood, and replace the broken bits with good stuff. I will be getting round to this with my reno racer...errrr....soon!


AlistairT