PT109 Conversion

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22 June 2018 at 14:44 #77684
Matthieu Burleraux
Participant
@matthieuburleraux21541
Hi guys,

Me again, sorry last topic I promise! While in Thailand for work for a few weeks I have a Revell PT109 I would like to convert.

I like "realistic" boats so I was thinking 3 engines but due to the size it should be very small engines to stay realistic(20w each max). I was been looking for brushless for weight reasons, otherwise a good old brush one (max 280 but smaller would be better).

If my calculation are correct if I get a 280 with let's say between 8k and 10k RPM at 6v it's a brushless between 1300 and 1600kv. But in my opinion that's too big and I would rather run tiny engines of 400Kv to 750Kv each.

Do you think it's feasable?

Edited By Matthieu Burleraux on 22/06/2018 15:02:52
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22 June 2018 at 14:44 #5527
Matthieu Burleraux
Participant
@matthieuburleraux21541
What motors
22 June 2018 at 16:36 #77689
Paul T
Participant
@pault84577
Hi Matthieu

I applaud your wish to put three motors and all of the ancillary equipment into such a small model, speaking for myself I would just use one motor on the center shaft.

Paul
22 June 2018 at 16:55 #77692
Matthieu Burleraux
Participant
@matthieuburleraux21541
I saw some with two brushed, was thinking 3 brushless as they are smaller, all controled by a single ESC and 2mm shaft if I can find some in this damn country… You would go with a single one then? a 280 would be enough with a 3 blade prop?

My main concern is actually weight and weight distribution more than size but it would be my first conversion so any type welcome and I might scale down on what I wanna do…
22 June 2018 at 17:05 #77693
Colin Bishop
Moderator
@colinbishop34627
Paul is right, by packing too much in it could make the model too heavy and lower the freeboard. Putting in three motors is unlikely to have much extra effect on practical performance at this scale. The usual practice is either to put in two independently driven screws to improve handling or one overscale one for simplicity. The non driven propellers can simply be left to freewheel or remain locked.

Colin
22 June 2018 at 17:20 #77695
Matthieu Burleraux
Participant
@matthieuburleraux21541
So basically two small engine or just one. I am not planning on making it a super fast boat, the hull isn't design for it. Freewheel is better in that case less drag for the remaining prop so will do that.

Any idea the kind of power/weight it can support without being a powerhouse? Can't find much data, most people did it with bigger models only and for the same model usually people don't give much explanation.
22 June 2018 at 17:43 #77698
Colin Bishop
Moderator
@colinbishop34627
It's actually quite a small model for r/c conversion. Most people go for the bigger Italieri version. I think you will only be able to put one motor in it. without getting involved with micro engineering.

There is a video of a conversion here:

**LINK**

And you might find some other material if you Google Revell PT 109 rc conversion.

Colin

Edited By Colin Bishop on 22/06/2018 17:43:25
22 June 2018 at 17:51 #77699
Matthieu Burleraux
Participant
@matthieuburleraux21541
Yes I googled and watched a bunch of youtube videos, some are pretty old or not very informative. Gonna do it over the weekend will share it with you once done
22 June 2018 at 23:28 #77707
Francis Macnaughton
Participant
@francismacnaughton39461
I assume we are talking about the recent 1/72nd release. From my experience converting the Airfix Vosper MTB which was in MB in 2016, you would need to look at ultra lightweight RC gear to keep near scale displacement and also get the model on the plane. I used a Deltang Rx 60-3 type from Micron:

**LINK**

The motor is a Parkzone PKZ3624 geared type also via Micron driving a Deans marine 18mm 3 blade prop
23 June 2018 at 03:35 #77708
Matthieu Burleraux
Participant
@matthieuburleraux21541
My kit was from around 2012 I believe with the old mold from the early 60's….

I can't find the spec of your engine, just that it weights 6gr and has a gearbox. Any info on that? I will keep everything light indeed.

Your boat looks awesome by the way!
23 June 2018 at 08:56 #77710
Francis Macnaughton
Participant
@francismacnaughton39461
I am familiar with the old PT109 having built one for static display – I don't expect there will be much difference in weight. Sorry, I don't have any other info on the Parkzone motor beyond that it provides a healthy level of power on a 3.7V LiPo source and seems to match the prop quite well in this sort of application
23 June 2018 at 12:05 #77711
Matthieu Burleraux
Participant
@matthieuburleraux21541
Thanks. The info was just to find a similar motor here, otherwise will just bring it back to Europe.
23 June 2018 at 18:28 #77713
Francis Macnaughton
Participant
@francismacnaughton39461
The best I can suggest is to see what small ready to fly indoor flier models are available locally equivalent to the Parkzone P51D and see if they have spare motor gearbox available – I suspect you are a lot nearer where all these items are made than we are in UK!

I weighed my static PT109 and it comes out at 115 grams which leaves you 35 g for all the RC if you are aiming for something near the 56 tons of the original.
26 June 2018 at 14:04 #77752
Matthieu Burleraux
Participant
@matthieuburleraux21541
Thailand is very near the production sites but everything important is heavily taxed… But yes I will get a brushless for a drone weighting around 6gr, trying to find small shaft but i guess I will go with a 3mm one and small 3 blades prop.

Now needed esc, rudding and the servo that goes with it.
26 June 2018 at 14:40 #77754
Paul T
Participant
@pault84577
Matthieu

For a prop shaft you might consider a pushrod from an r/c aircraft.

The one on the top right of this image might give you some ideas.

Good luck in Thailand

Paul
26 June 2018 at 15:18 #77757
Matthieu Burleraux
Participant
@matthieuburleraux21541
Thanks! Then you just glue the prop to the shaft? 3mm shaft sounds good to you? What about the prop size? Sorry first time I am converting something. Will probably be a nylon one anyway.

This is the motor I will get. 4000Kv/38W is more than enough, otherwise the other one in the same weight class is twice more powerful…

Thailand sucks to be honest so this hobby is more than welcome! Can't wait to be back in France where my biggest projects are.
27 June 2018 at 11:47 #77769
Paul T
Participant
@pault84577
Given the small size of both shaft and prop I think that gluing is the best option.

I recall that Thailand is hot and sticky especially away from the coast.

Paul
28 June 2018 at 13:09 #77806
Matthieu Burleraux
Participant
@matthieuburleraux21541
it is always hot and sticky. What they call winter is when it's 27c outside…
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