Another billings slo-mo-shun

[Bob Abell 2Participant @bobabell2]

OK Phil…..Just checking

There`s no rush at this time of year

We`ve got the big freeze again, here in Manchester

Bob

[Phil Winks 1Participant @philwinks1]

As I said Bob we’ve thankfully had a thaw since yesterday and outside temps currently about 6 degrees (positively summer like LOL) so hopefully tomorrow will see suitable weather.

I’m going to charge the bty’s up and grease the prop shaft this afternoonready just in case.

Phil

[Phil Winks 1Participant @philwinks1]

Well last weekend I got too busy, but this week, after good weather all week, I thought yes we’re on.

 

So got all charged up and camera at the ready, arrived at the pond, and after the 1st cold snap in a fortnight last night, the ruddy ponds solid again dooh

 

Keep on trying Philip LOL

[Bob Abell 2Participant @bobabell2]

We are frozen at this end too!

 

Had a look at the garage gutter barrel and it`s split from top to bottom!

 

Such is life!

 

Bob

[Phil Winks 1Participant @philwinks1]

I just couldn’t believe it Bob we’ve had great weather for a fortnight and one little frost and its frozen again. and it was such a lovely day too quite warm in the sun.

 

Phil

[Bob Abell 2Participant @bobabell2]

Any progress, phil?

 

Bob

[Len OchiltreeParticipant @lenochiltree67043]

Hi Bob,

What is the latest on your one ?.

 

Len.

[Phil Winks 1Participant @philwinks1]

Unfortunately Bob the weather and my spare time are in the habbit of not coinciding I’m afraid. Think I mentioned before the bath test was scary a less than half full bath and a quick run up to full throttle and the floor got just a little damp lol. on the plus side the ammeter only showed 8A so if the test is disappointing there’s the option of a bigger / courser prop as I have a max of 26A avaiable and this was on the lower voltage bty so more revs are available too.

 

Phil

[Bob Abell 2Participant @bobabell2]

Thanks for the latest info, Phil

 

Len…….No progress with my boat either……..Just gathering dust in the workroom

 

Waiting patiently in the wings, on the look out for the legendery brushed motors that will come up to scratch.

 

The brushless option is far too expensive at the moment

 

Thanks Phil

 

Bob

[ashley needhamParticipant @ashleyneedham69188]

I have never set much store on the bath test for power consumption or thrust…they just are not big enough. Phil I dare say the 8A you saw was not fully representative of your slo-mo`s full potential, and as you say, the water goes everywhere.

 

It`s ok for smaller or lower powered models or to give a rough indication, sometimes.

 

I recon a test tank to give a better reading would have to be long and deep but who has the room or a wife willing to allocate that much garden for testing model boats.

 

Mind you, when I tested my SRN4 test vehicle for hovering capability (a grand name for something as bodgy as it was) I did it in a builders knocking up plastic tray thing with only 2″ of water!

 

Ashley

 

 

[Phil Winks 1Participant @philwinks1]

Hi Bob and Ashley.

 

I find the static test in the bath produces the same results as a tethered test at the pondside. the water wasn’t spraying directly from the prop simply the stream of water running back down the length of the bath welled up towards the taps and some spilled over the side the water level in the other end visible dropped by nearly an inch or so and the push of the boat required a very firm hand to control

 

If I’d felt that level of push from a 1.5kg model back in my aeroplane days I would’ve been able to guarentee a flyer

 

So I really am confident that we’ll see good results when the good weather and my spare time finally coincide

 

Phil

[Phil Winks 1Participant @philwinks1]

Ok gents the time when good weather and my free time finally coincided and of to the pond I trotted with the old lady firmly tucked under my arm and a fresh 7.4v bty tucked inside her.

 

The results were pleasing although she does need trimming further forward and I wish I’d taken the 11.1v bty with me however watch the vid and judge for your selves.

 

the long awaited video

 

She rides slightly nose high and could do with a tad more speed, However changing the bty to a 3s1p (11.1v) will most likely address these two issues in one move

 

On the whole though I’m well pleased she gets on the plane without fuss and although the stern is a little deep one can see air under the hull aft of the sponsons.

 

Needless to say I left the pond with a cheshire cat like grin

 

Phil

[ashley needhamParticipant @ashleyneedham69188]

Phil. That looks really good, and although it may not be as fast as you would like, I think it is on the money as they say.

 

The trouble with model boats at speed, in my eyes, is that they start to “skip” and bounce unconvincingly over the non-scale water and waves and start to look like lightweight R-t-R types. Your vid shows old Slo-mo as being planted and fairly quick, or at least quick enough to look convincing.

 

You should be well happy with that.

 

Ashley

[ashley needhamParticipant @ashleyneedham69188]

Phil. That looks really good, and although it may not be as fast as you would like, I think it is on the money as they say.

 

The trouble with model boats at speed, in my eyes, is that they start to “skip” and bounce unconvincingly over the non-scale water and waves and start to look like lightweight R-t-R types. Your vid shows old Slo-mo as being planted and fairly quick, or at least quick enough to look convincing.

 

You should be well happy with that.

 

Ashley

[ashley needhamParticipant @ashleyneedham69188]

whoops !!

[Bob Abell 2Participant @bobabell2]

Well done, Phil…….Action at last!

 

The motor doesn`t sound like a brushless type?……..It hasn`t got the familiar high pitched whine?………..Would a smaller prop get the revs up?

 

Bob

 

 

 

 

[Phil Winks 1Participant @philwinks1]

thanks for the kind comments lads.

 

Your right about it not needing much more speed Ashley however I would like to get her slightly more nose down when on the plane. otherwise yes I’m chuffed to bits with her.

 

Bob my old mate that’s such a common misconception with brushless motors, every one expects that they rev their nuts off!

agreed with the FE boy’s being the 1st in our hobby to employ them that’s the impression they give

 

however this motor is relatively low revving at 900 rpm/V and that prop isn’t slowing it one jot such is the torque of these low kv motors

 

hence my plan to up the bty from 7.4 to 11.1v that’s a 50% voltage increase and so a 50% rev increase in theory. in fact prob more like 40% as the poor old motor is only 93% efficient (as opposed to about 60 or 70% for a brushed motor)

 

also the extra weight of the bigger bty will just about tip the nose down a touch getting her bum out of the water a bit more.

 

And if that fails to get her level on the plane then a stepped hull modification is planned with a step of just 4mm, just forward of the prop.

 

then hopefully the prop will run true surface and that will increase its efficiency and as a bonus produce the charicteristic rooster tail that the old lady was famous for. (at 178mph she had a 1/4 mile rooster tail containing an estimated 1/2 a ton of water in it)

 

Phil

[Bob Abell 2Participant @bobabell2]

Hello Phil

 

If the prop is not slowing one jot…..then try a bigger prop?

 

Just a suggestion………Bob

[Phil Winks 1Participant @philwinks1]

Hi Bob

a larger prop is another option after I’ve investigated the larger bty and then the minor mod to the hull. which incidently may take the form of small deflector plates either side of the external section of the prop shaft just to lift the stern at speed

 

the advantage of not going larger on the prop is Amps currently there’s about 40 mins of bty life on this prop a larger one would increase the Amps and thus shorten sailing time and consequently the increased load on the bty will to some extent shorten its usable life re the number of recharges needed

 

 

Phil

[Phil Winks 1Participant @philwinks1]

Just a quick report.

 

I had some time off this morning and used some of it to try the bigger bty out,

 

I’m pleased to report that the extra power and conseqent slight shift forward of the balance worked a treat there really is no need to develope her further.

 

she is app 30% faster and the stern rises nicely so she is level on the plane.

 

I did take the camera but wasn’t able to safely steer her and video at the same time.

 

such is the extra speed that the size of the pond has become a problem taking just a few seconds to cover the 40yds or so of open water available..

 

She still looks planted on the water and although faster she isn’t ridiculously so also some semblence of a rooster tail is evident at top speed, which adds greatly to the sense of realism.

 

I will have some one with me on sunday who may be able to follow her with the video camera so I do hope to put a final video up then.

 

Phil

[ashley needhamParticipant @ashleyneedham69188]

Phil. This is a bit of a problem with fast boats, they cover so much water so quickly that the speed becomes a bit unusable except in short bursts.

 

But what the hell, eh !!!!

 

Ashley

[Phil Winks 1Participant @philwinks1]

Too true Ashley

 

now I want to take it up too burnham. Apex lake is about 200yds across and unsuprisingly the club there have a good number of fast electric models

 

 

Phil

[Phil Winks 1Participant @philwinks1]

Finally got a vid of her on 3 cells for you all not the best quality really must invest in a decent camera.

 

 

Slo-Mo-Shun IV on a 3s1p bty

 

 

Phil

[Bob Abell 2Participant @bobabell2]

Hello Phil

 

I`ve had a look at your video and your boat is going quite well. but it`s not exactly flying!

 

Sorry Phil….the motor should be whistling……..I know you`ve selected a slow revving motor for some strange reason. intentionally……and you are the expert

 

The motors at Bury Metro absolutely scream and howl beyond belief and jump across the wavelets and are airborne for about 2 metres at times!

 

That`s what I was hoping for on your model

 

Don`t take offence, old chap…..but you went to all that trouble making your model as light as a feather for a sparkling performance

 

But if you are happy….That`s all that matters!

 

Only my opinion, Phil………. Bob

 

[Phil Winks 1Participant @philwinks1]

No offence taken Bob but, if we go back through this thread I’m sure my intention from the off was to produce a scale model with scale performance and that roughly equates to 14mph now she’s prob well over that closer to 20 so aim achieved I’d say.

 

However the idea of making her exceed more than double scale speed has occoured to me and it would be a simply matter to fit the 3600kv (revsx 4 x as fast) version of this motor and do that however I would no longer be able to effectively sail her on that pond, and she would sit on the shelf except for 1 or two outings to apex and an outing to the river in tauton each year,

 

To be honest I like sailing her, and with this set up she’s going to pretty well live in the car during the summer, for impromptu trips to any bit of water I’m passing lol

 

Many thanks again for the model, she is already attracting great interest every time she goes out, and is responsible for at least one new member to our little club, and she’s only been out 3 times so far.

 

Phil

[Author]

Posts