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If I fit floats to my Senior Telemaster will I need a more powerful engine?

Planning ahead!

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David Davis09/06/2019 08:35:42
3841 forum posts
741 photos

My Barn Door Wing Senior Telemaster is starting to look extremely scruffy and I plan to strip off the covering over the coming winter, repair the glider tow release and anything else that needs attention and recover it. I like to plan ahead!

Senior Telemaster

One or two members of my club have got into flying from water over the last year or so and I thought it would be ubercool to fit floats to the STM and have a go. I built hard points for floats or skis into the fuselage when I first built the model and these floats seem to be value for money: **LINK** I have never weighed the model but as it's covered in Solartex and features extra servos for flaps and the tow release I expect it's rather heavier than most STMs. It is currently powered by a Thunder Tiger 91 FS.

Would a more powerful motor be advisable for float flying?

Denis Watkins09/06/2019 08:51:29
4634 forum posts
129 photos

Just the numbers David

A regular Senior Telemaster is around 6lb, and maybe yours is 7lb

Your floats are just over 1.5lb, so by weight a .90fs is adequate for a high winger

Nick Cripps09/06/2019 09:23:35
57 forum posts
22 photos

I agree with Denis.

I would imagine that the TT91 is more than adequate for your STM currently so the extra drag and weight of the floats would easily be coped with. Adding yet more weight with a larger engine just isn't necessary.

More important is to get the dimensions of the floats correct to support the weight of the model on the water and especially important is the positioning of the step so that the model can rotate and take-off successfully.

The Windermere Model Waterplane Flyers website is worth a look, this write-up by Phil Davies provides some good information:

Getting started

Also worth a read is Chuck Cunningham's article from RCM Magazine:

Float Flying

Levanter09/06/2019 09:47:47
883 forum posts
437 photos


All of the above.

If you have been pulling gliders you should have more than enough grunt to pull the floats.

The only thing I might add concerns longitudinal directional stability. Many floatplanes both full size and models have a vestigial fin under the existing fin to give a bit more area aft of the floats. This is because the floats sit well forward to prevent nose-overs (well that's the idea wink)


Don Fry09/06/2019 11:06:40
4557 forum posts
54 photos

Bloke who wrote the Windermere article has a knack off getting the subject covered in few words. If you are flying with a glow plug, fit a water rudder. They can be a bitch to direct and there is no reverse like a leccy floateur.

Levanter09/06/2019 11:28:27
883 forum posts
437 photos

Be prepared

This chap was.

Agree with Don on the water rudder(s)


Steven S09/06/2019 13:36:05
369 forum posts
193 photos

When I bought the optional float kit for my electric powered Sport Cub it came with a new prop.

float prop.jpg

Edited By Steven Shaw on 09/06/2019 13:38:11

Nick Cripps09/06/2019 13:41:16
57 forum posts
22 photos

For those who are interested in trying out float flying, the British Waterplane Association organises 3 events a year at Colwick Park in Nottingham and have monthly meetings at Billing Lake near Northampton.

You'll be guaranteed a warm welcome and any assistance you might need with this fascinating branch of our hobby.

Dates for these and other events around the country can be found on the BWA website:


Tony Richardson09/06/2019 22:26:09
657 forum posts
25 photos

Your TT91fs will be more than enough power for the Telemaster on floats David, you should read the Chuck Cunningham article it is all good stuff, I would remind you once you have everything set up and you are good to go when you make that first takeoff once in the air you will most likely need a bit of pitch up trim due to the floats being low and causing drag, possibly pitching the nose down, I always like to have a buddy standing with me at such times to give me trim if needed, just for peace of mind.

Have fun flying from water is another aspect of this hobby that makes it so interesting..

David Davis09/01/2020 14:06:54
3841 forum posts
741 photos

Well I've gone and bit the bullet and I've bought a set of ready-made floats. I thought I'd prepare a model for floats over the winter. The floats were advertised on the internet advertised as being suitable for models weighing up to 5kgs or 11lbs. I had intended to fit them either to my Senior Telemaster or perhaps to my WOT 4 XL. When they arrived they turned out to be VQ Model 635 2481 Floats intended for a 40-46 size model.

I consulted the book "Radio Control Airplane Workshop Secrets" and was advised that the length of the floats should be 75% of the length of the fuselage. As the floats are 92cms long or almost exactly 36" then the maximum fuselage length should be 115cms or 48".

My Senior Telemaster, with flaps, Barn Door ailerons, spruce spars and a glider tow release weighs 12lbs 4ozs (5.5kgs) and its fuselage length is 1.5 metres or 60" so it fails to meet the criteria for both the weight or the fuselage length.

Senior Telemaster

My WOT 4 XL has a fuselage of only 48" but it is powered by a 150 V twin fourstroke. In the picture it has an Enya 120 FS installed. The problem with the WOT 4 XL is that underside of the fuselage is far from flat which may make the installation of floats difficult.

wot 4 xl 1.jpg

I have a vintage Uproar, a replica of the model which placed second in the European Airobatics Championships in 1959. It has a flat fuselage bottom but it only has a tiny rudder so whether that would be suitable as the basis for a float plane I don't know.

nearly there. (2).jpg

Otherwise I could build a Telemaster 40 fuselage and tailplane. I still have the wing. It broke off one day when I was demonstrating the model to a potential buyer! That'll teach me!

rip t40 (1).jpg

Or I could buy an ARTF 40-46 size trainer and convert that.

What are your views?

Alan Gorham_09/01/2020 14:36:13
1321 forum posts
146 photos

David in general it is much easier to select a model you wish to put floats on and then design and make a set of floats to suit.

You will get much better results doing it that way because you have total control of the float length, step position relative to the aircraft cg and total float volume.

If you compromise on any of those factors you will get poor water handling and poor take-off performance. An model with an ideal setup should be able to come up on the step and then take off just by opening the throttle in my experience.

A sub-optimal setup may need the presence of a chop on the water to help get up on step, or some hefty elevator work that may lead to the model taking off in a stalled attitude etc.

Also, if you get the relative length of the floats correct you will find you can manouevre the model on the water without water rudders. I don't use them generally.

As well as float length v fuselage length, you need a set of floats that are proportioned so that the float noses come out to around half a prop diameter in front of the prop arc and with the step positioned around 1/2 to 3/4" behind the CG.

It is worth persevering to get all the parameters right because it is fantastic fun flying from water. here are some of my own models with own design and made floats:

flair cub float.jpg

img_2126 (600 x 417).jpg



Alan Gorham_09/01/2020 14:37:40
1321 forum posts
146 photos more conversion I just remembered:


Don Fry09/01/2020 17:20:28
4557 forum posts
54 photos

Sarik do "superfloats", search on that.

they are the floats for 12 to 18 lb planes, and in particular, the Giant Jabberwok. Easy enough to make. While they will do you, you might just use the plan for structural integrity, mounting solutions, and redraw to get the proportions right. There is a whole world between a nicely proportioned float, set at a good angle to present the wing to airflow, and a properly positioned step allowing it to rotate and rise. Or something which you have to yank off the water, into an incipient stall.

Just for fun, if you have a nice trike aircraft, not a bitch mind, try changing the front wheel for smaller, and the mains for bigger wheels. You will get an idea.

Gordon Whitehead 109/01/2020 19:15:49
348 forum posts
157 photos

If you're going to fly sometimes with floats and at other times with the land u/c, you need to take steps to ensure that the model's CG is always correct for the configuration in use without having to add or remove balance weight during the changeover. If you forget to make the balancing weight adjustment, you might end up with enough of a rearward CG to lose the model in an unintentional low-level spin.

I speak from experience with my one and only floatplane conversion of a model which usually flew as a landplane.

It's likely that the extra lift from that portion of the floats in front of the propeller will require weight added in their noses to move the model's balance point a tad further forward in floatplane configuration as compared with landplane configuration. So you should set up the model's CG for its landplane configuration first. Then, having established where the CG should be for the model as a floatplane, add weight to the floats permanently so that when converting from landplane to floatplane, the CG will be automatically correct the instant the floats are secured in place. I didn't get around to adding permanent balance weights so that through a moment's inattention when adding the floats before (its final) flight which my Dad was going to video, I forgot to add weight to the model's nose, with the eventual unfortunate consequence mentioned above.

Your flaps should come in handy for taking off from a smooth unruffled water surface. Never having seen mention of this, on the first flights of the model I eventually lost, I scooted the model around to create ripples per the conventional advice for aiding unsticking. Eventually, I discovered that lowering the model's flaperons, which I had always used previously for take-offs in landplane configuration, negated the need for ripples, so I lowered the flaperons for all future take-offs.

Chris Channon09/01/2020 21:45:25
554 forum posts

Evening all, reading this thread, lots of very interesting and knowledgable people on here. This would make a brilliant article for the magazine. I am interested in making and fitting floats to my Precedent Stampe.

Thanks all


Don Fry09/01/2020 22:11:52
4557 forum posts
54 photos

Balsa USA used to do a set a quarter scale floats.

But I don't know what information comes with the floats to adapt them to our use, or rigging angles, or the practicalities of sticking them on a flying aircraft.

David Davis10/01/2020 05:43:56
3841 forum posts
741 photos

Thank you for all of your advice gentlemen.

The floats came with instructions on how to mount the floats e.g., mount the step at the centre of gravity, with the top of the floats level, the wing incidence should be 1,5 degrees,floats should be parallel to the centre line of the fuselage and lead should be placed at the front of the floats to being the cg 9-10mm in front of the manufacturer's recommended position.

Given that I've already bought the floats, and given that the fuselage of the model should be 25% longer than the length of the floats, I am considering building another Telemaster 40 fuselage and tailplane as the length of its fuselage is 45" (114 cms) which is about right for these floats. As you can see in my previous post, the tailplane survived the crash but two house moves later it has disappeared.

I am wondering whether to fit an electric motor as per my original Telemaster 40, or whether to fit a four stroke engine. I have a few homeless 48-70 four strokes which would fit.

Rapsody in Blue!


Alan Gorham_10/01/2020 09:32:34
1321 forum posts
146 photos

Personally, the vast majority of my waterplanes are powered by a nice oily engine as you can get an engine wet from spray blown up from the prop or turning the model turtle and put the engine back into service very quickly the same day by just emptying out any water from the glowplug hole, rinsing out with fresh fuel, before putting the plug back and starting the engine, getting it right up to operating temperature and that it.

So long as your engines are reliable (ie will keep running so long as there's fuel in the tank) and will idle for long periods and pick up instantly everytime, there is no problem.

Electric power is obviously immune to any running issues, but is more susceptible to a good wetting. The motor and ESC especially. They can usually be rescued but they must be dried out very thoroughly.

Alan Gorham_10/01/2020 09:45:00
1321 forum posts
146 photos

David, based on the information you've given about the floats in your previous post this morning, I would urge you to check one more dimension against your proposed fuselage....

If you lay the fuselage plan out and lay the float plan out in the "installed" position ie with the step in relation to the CG as per the manufacturers instructions, do the noses of the floats stick out ahead of the prop by at least half the proposed prop diameter?

If they do not you will find the model hard to get up on the plane and in the worst case, opening the throttle will make the floats want to dig into the water, pulling the models nose down. Now is the time to resolve that question!

Nigel R10/01/2020 11:21:50
4082 forum posts
694 photos

David, maybe this is of some help - I built an RM Trainer a while ago - see plan here on outerzone 

It is, like many cabin trainer types, very similar to your Telemaster - albeit smaller.

Boddo was a keen waterplane flyer, I believe. And the plan shows float construction. At the time I didn't even consider floats (although since then the amount of rain we've had is making me think again!). Either way, they look pretty simple to scale up (or down) and show some straightforward methods of fixing them to the fuselage. Plus it shows their location and angle. It also shows an increased size fin to use with them, which could help you gauge how much extra rudder area you might need.

Maybe I'll make a standard size pair for mine...

Edited By Nigel R on 10/01/2020 11:22:03

Edited By Nigel R on 10/01/2020 11:22:27

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