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OS 25 FSR- Equivalent

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Tosh McCaber13/01/2019 12:35:25
11 forum posts
5 photos

Quite a few years ago, I used to have an OS 25 FSR- one of my favourite engines- powerful, and easy to use- unfortunatel permanently dismantled in a collision withn a Scoittish Loch at a water fly-in.

I'm just getting back into the game. Can anyone say what modern engines might be the FSR's equvalent?

Thx for any suggestions in advance!

Martin Harris13/01/2019 12:40:43
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8870 forum posts
221 photos

Unfortunately, electric flight has made serious inroads to the production of small engines - second hand would be the most likely option. The Irvine 25 was an excellent engine with good power, SC/ASP 25s were OK but not as well made and OS had the 25 FX and AX (the LA series were plain bearing and less powerful) but none of these are being produced currently as far as I'm aware.

P.S. Just engines still list the 35 AX as available - a bit bigger but could be a possibility?

Edited By Martin Harris on 13/01/2019 12:50:46

CARPERFECT13/01/2019 12:50:21
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490 forum posts
7 photos

Your best options are OS. They make a 25 fx that produces .84 HP at 18.900 rpm

Or the 35 ax that produces 1.28 HP at 16.000 rpm

So if its power to weight ratio you want then the 35 ax is the one.

Info from OS website just now

Nigel R13/01/2019 13:03:45
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3100 forum posts
479 photos
In all honesty the best modern equivalent is electric.

I thought Os are dropping their smaller engines and the smallest is now the 35.

The only two stroke options - realistically- are second hand. Most manufacturers have got out of two stroke glows because nobody is buying them.
Frank Skilbeck13/01/2019 13:09:21
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4488 forum posts
101 photos

Same here, my 25 FSR got wrecked a few years back, I acquired a new in box OS 32 last year, for not a lot, it's a peach of a motor.

kc13/01/2019 13:25:23
6053 forum posts
169 photos

I would look for an Enya 30SS plain bearing - a super little engine , as small as a 25 but as powerful as some .40's and no ball races to corrode. Often very cheap SH as Enya is a top brand that has been forgotten. Or the 25SS in either plain bearing or ball race.

Nowadays the best thing is to ask your clubmates if they have an engine for sale, wirth so many going over to electric it's likely you will find an ic available.

Tosh McCaber13/01/2019 13:36:47
11 forum posts
5 photos

Many thx for the replies.  I know that this is ic territory, but you mention electric being an option. I still have the aeroplane, (for slight reconstruction!)- Corkscrew RC sport aerobatic- wingspan 49in from RC Modeler Jan.1983- great performer!

Any lead ins as to an electric motor size and battery?

Or should I try the electric forum?

Any suggestions appreciated!

Edited By Tosh McCaber on 13/01/2019 13:38:44

Peter Miller13/01/2019 13:52:22
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10250 forum posts
1225 photos
10 articles

Unfortunately no SC 25s or 32s available at the moment.

For really good, sound advice on electric power phone George at 4-Max. on 01256 782512

Edited By Peter Miller on 13/01/2019 13:52:56

Martin Harris13/01/2019 13:53:27
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8870 forum posts
221 photos

The advice on the OS site conflicts with Just Engines who state that the 25 is discontinued. I'd suggest that the OS site may not have been updated regularly of late.

If you do go down the electric conversion route, be prepared for a steep learning curve. While pre-installed or specified power trains are very simple to use, you have a lot of variables to play with - especially when trying to equip models not designed to accommodate batteries and your best route, unless you have a thorough understanding of the relationships between motor kV, battery cell numbers, propeller sizes, current capabilities of components and C ratings (to name the most important factors) would be to seek advice from experienced clubmates or forums (there are many expert - and not so expert - electric flyers on this forum).

kc13/01/2019 14:21:18
6053 forum posts
169 photos

Electric flight can be quite simple if you just choose a setup that works on a similar style model. You only need to keep to the same motor, same KV, same prop, same number of cells, same or larger ESC.

For example I have a 4lb weight aerobatic model ( actually a Moronic but think of a 52 inch Wot4 as similar) uses Turnigy 3536/9 910kv motor with 11by 5.5 APC electric prop. Lipo is 4S 3000. ESC 40 amp. Gives about 500 watts and draws 33 amps. That is just over the 100 watts per pound that is usual minimum for aerobatic models. This setup will work with any similar model ( in my opinion ) and weight is much the same as a .46 glow that it replaced in that model. The big difference is the weight is all further back so the nose was extended to avoid using lead. And flight times are only about 6 minutes at full throttle.

I don't know the Corkscrew model but its probable it could be electrified just like my model. Whether it's worth hacking the model around to extend the nose and putting a hatch to access the Lipo is up to you. Might be better to start with a purpose designed electric model to start with - I suggest you consider the Peter Miller Ohmen from RCME Oct 2018 free plan ( probably back number magazine still available) as a good start in electric. Simple construction and the electric motor is specified and still currently available.

kc13/01/2019 14:38:36
6053 forum posts
169 photos

I have just looked up the Corkscrew plan and article on Outerzone and it looks an easy conversion to electric if the engine bearers dont get in the way of the Lipo.

Paul Marsh13/01/2019 14:57:41
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3725 forum posts
1055 photos

There is a 25AX. The older FX series were good, I bought one new in box last year for £5!

Edited By Paul Marsh on 13/01/2019 14:58:34

Tosh McCaber13/01/2019 16:05:53
11 forum posts
5 photos

Thanks for the (very prompt) and useful replies guys. I have the Oct issue with the Ohmen, thanks. I'll study the specs on it and take it from there!

The Corkscrew was (is) a brilliant little aerobatic flyer. The secret's in the name! It does wonderful continuous flat spins- start with a Lomchevac and keep the control positions on the sticks, as noted in the the precis of the article on Outerzone, linked above by kc. I built it from the RCM plan, followed by a squadron of them in my local club when they saw it fly!

Can't believe that that was in 1983!!

Solly13/01/2019 16:44:21
241 forum posts
1 photos

WestonUK sell the West 25 glow engine. A lovely piece of engineering.

Caveman13/01/2019 19:20:34
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266 forum posts
237 photos

Tosh, how about this:

FAAAOSwXnxcOy3x:rk:8f:0&LH_Auction=1">https://www.ebay.co.uk/itm/OS-25-FX-2-stroke-R-C-Model-Aircraft-Glow-Engine/123593047892?hash=item1cc6b83f54:gFAAAOSwXnxcOy3x:rk:8f:0&LH_Auction=1

also, Airtek Hobbies have an SC25A in stock (?)

**LINK**

or a 36 if you want a bit more grunt

**LINK**

GDB

Edited By Caveman on 13/01/2019 19:21:20

Tosh McCaber13/01/2019 22:02:13
11 forum posts
5 photos

Thanks again!

Percy Verance14/01/2019 06:49:22
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8108 forum posts
155 photos

Hi Tosh

If you're able to source one, I'd look at the MVVS .28. Both Just Engines and Puffin Models used to sell MVVS engines, but I'm not sure who is bringing them in these days.

MVVS are a Czech manufacturer whom have been manufacturing model engines almost as long as OS. Indeed, the internal engineering of their engines matches OS, and so does the performance. Many control line speed and team race events have been won by MVVS powered models over the decades. Indeed, a chap Named Hanno Prettner even used MVVS engines at one time. I owned several of these engines a while ago, one being the .28 capacity job. It was an absolutely cracking little engine. I flew mine in a small delta, which it pulled with great authority. I was most impressed with both the performance and throttling, which was easily as good as any OS engine I'd owned.

See if you can track one down Tosh, you wouldn't regret it. yes

 

Edited By Percy Verance on 14/01/2019 06:51:51

Percy Verance14/01/2019 06:49:24
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8108 forum posts
155 photos

Hi Tosh

If you're able to source one, I'd look at the MVVS .28. Both Just Engines and Puffin Models used to sell MVVS engines, but I'm not sure who is bringing them in these days.

MVVS are a Czech manufacturer whom have been manufacturing model engines almost as long as OS. Indeed, the internal engineering of their engines matches OS, and so does the performance. Many control line speed and team race events have been won by MVVS powered models over the decades. Indeed, a chap Named Hanno Prettner even used MVVS engines at one time. I owned several of these engines a while ago, one being the .28 capacity job. It was an absolutely cracking little engine. I flew mine in a small delta, which it pulled with great authority. I was most impressed with both the performance and throttling, which was easily as good as any OS engine I'd owned.

See if you can track one down Tosh, you wouldn't regret it. yes

Edited By Percy Verance on 14/01/2019 06:51:18

Robin Etherton14/01/2019 09:27:49
271 forum posts
41 photos

There are plenty on ebay.

I also had one of these with a tuned pipe in a rc model way back.

What a motor, shed loads of power on tap instantly. Never missed a beat.

Have now gone over to the dark side(electric)

Nigel R14/01/2019 09:29:23
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3100 forum posts
479 photos

MVVS have no glow engines listed as current on their website.

Puffin have no working online shop, didn't they close last year?

I'm not sure who is left making small glow motors now.

West are flying the flag here.

OS do 35, 45, 55, 75, 95 and 120 I think.

Novarossi do a 60, think they do a 46, don't know about smaller sizes, they definitely do small car engines.

edit: the novarossidirect website (USA) is showing an aero version of .9, .12, .15, .21, .28, .46, .60, .75 and .90. Also headers and tuned pipes.

Jett?

 

 

Edited By Nigel R on 14/01/2019 09:35:57

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