From the late 1980's - it was quite a few years behind the times but very cheap.
More words and photos on my build log here:
https://www.rcgroups.com/forums/showthr ... taire-Tyke
From this
Rotaire Tyke
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davejones
- Posts: 22
- Joined: 16 May 2022, 10:06
- Location: Hervey Bay Australia
Rotaire Tyke
I've just about finished restoring an obscure English fixed pitch heli designed by a Tim Angel.
From the late 1980's - it was quite a few years behind the times but very cheap.
More words and photos on my build log here:
https://www.rcgroups.com/forums/showthr ... taire-Tyke
From this To this
From the late 1980's - it was quite a few years behind the times but very cheap.
More words and photos on my build log here:
https://www.rcgroups.com/forums/showthr ... taire-Tyke
From this To this
Dave Jones
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Pchristy
- Posts: 417
- Joined: 16 Feb 2018, 13:57
- Location: South Devon, UK
Re: Rotaire Tyke
I remember test flying one of these for a guy decades ago! It flew extremely well, although the headspeed was remarkably low IIRC!
Martin Briggs here in the UK recently restored one and converted it to electric. Flies well!
Indeed, every old heli that I've converted to electric has flown much better than the i/c version!
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Pete
Martin Briggs here in the UK recently restored one and converted it to electric. Flies well!
Indeed, every old heli that I've converted to electric has flown much better than the i/c version!
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Pete
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davejones
- Posts: 22
- Joined: 16 May 2022, 10:06
- Location: Hervey Bay Australia
Re: Rotaire Tyke
Despite the nostalgia of running an old heli with a glow engine and castor oil smoke etc, I must admit I'd forgotton about the mess and the nagging thought in the back of your mind that the engine may just quit at a most awkward time.
A conversion to electric does sound like a good idea. I would do it as a reversible conversion with no extra holes drilled in the original chassis etc.
Pete - I've watched videos of your conversions and they perform very nicely. How do you go about calculating motor size, gearing, battery size etc?
Is there some sort of set formula that is used as a base calculation?
Dave
A conversion to electric does sound like a good idea. I would do it as a reversible conversion with no extra holes drilled in the original chassis etc.
Pete - I've watched videos of your conversions and they perform very nicely. How do you go about calculating motor size, gearing, battery size etc?
Is there some sort of set formula that is used as a base calculation?
Dave
Dave Jones
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bluejets
- Posts: 317
- Joined: 19 Jun 2019, 04:09
Re: Rotaire Tyke
This has always been a mystery to many ever since elctric was first used, seems especially in fixed wing aircraft probably due to the number used.
I Think there are "round about" conversion charts available online but I usually take the approx. output power (usable) of the glow engine and compare that to the new electric motor.
That's ok for the wattage using 746 watts as 1 HP.......... many more considerations given to choosing the motor such as kv ( theoritical thousand revs per volt battery power)
Most is a matter of suck it and see.
Naturally when it comes to electric, the battery size and weight must be a consideration.
Heli motors tend to run high revs and gear to suit main rotor requirements so they don't bog down under load.
A lot of heli-specific info online but takes millennia to get to it all.
Probably best initial approach is to see what others have used with success in similar systems.
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Pchristy
- Posts: 417
- Joined: 16 Feb 2018, 13:57
- Location: South Devon, UK
Re: Rotaire Tyke
All the information I could find online was aimed at fixed wing, where it is quite easy to "fine tune" things using different prop diameters and pitches. Not so easy for helicopters!
Perhaps if I go through the procedure I used for the Lark, it will help.
As a starting point, I look at the specifications of the engine for which the heli was designed. For the Lark, which was designed to fly on a 20/25 ci motor, I used the power figure for an HB25, which supposedly produced just shy of 0.6 HP at around 15,000RPM (higher than I expected!) - equivalent to around 440 watts. http://sceptreflight.com/Model%20Engine ... 025-H.html
Initially I was hoping to fly it on 3S, say 12V in round numbers.
So, we are looking for something that is rated at around 440 watts, with a kV rating of 15000/12 = 1250kV.
The motor I went for was an Overlander 3536/06. This is rated at 1300kV and 442 watts.
The model did fly on this, but was a bit marginal, so I upped the cells to 4S, which now provides sprightly performance! Most of the time, it is flying on around half throttle in the circuit, or just over half in the hover.
I should add that I couldn't get a primary pulley of 8T to fit the electric motor, so I had to go for the nearest I could get, 10T. This would have affected my calculations slightly.
Its also worth noting that these old British helis (Morley, MicroMold, etc) tend to use Imperial belts and pulleys (XL) rather than metric. The difference in the pitch of the teeth is not really visible (5.06mm Vs 5mm from memory), but will result in high wear rates if you get it wrong!
I used the same calculations for my Schluters, intended to fly on Blackhead Webra 61s (about 1.2 HP, or 900 watts). I came up with 500kV on 6S packs. Again, it flew on this, but was slightly underpowered. I ended up using 580kV.
As a result, my advice would be to use a slightly higher kV rating than you calculate!
As an aside, Phil_G, of this parish, came up with a simple formula for conversions as being 100 watts per cc of engine capacity! This agrees very closely with my figures, and makes for a very simple calculation! Moreover it works for helicopters just as well as it does for fixed wing! Cheers, Phil!
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Pete
Perhaps if I go through the procedure I used for the Lark, it will help.
As a starting point, I look at the specifications of the engine for which the heli was designed. For the Lark, which was designed to fly on a 20/25 ci motor, I used the power figure for an HB25, which supposedly produced just shy of 0.6 HP at around 15,000RPM (higher than I expected!) - equivalent to around 440 watts. http://sceptreflight.com/Model%20Engine ... 025-H.html
Initially I was hoping to fly it on 3S, say 12V in round numbers.
So, we are looking for something that is rated at around 440 watts, with a kV rating of 15000/12 = 1250kV.
The motor I went for was an Overlander 3536/06. This is rated at 1300kV and 442 watts.
The model did fly on this, but was a bit marginal, so I upped the cells to 4S, which now provides sprightly performance! Most of the time, it is flying on around half throttle in the circuit, or just over half in the hover.
I should add that I couldn't get a primary pulley of 8T to fit the electric motor, so I had to go for the nearest I could get, 10T. This would have affected my calculations slightly.
Its also worth noting that these old British helis (Morley, MicroMold, etc) tend to use Imperial belts and pulleys (XL) rather than metric. The difference in the pitch of the teeth is not really visible (5.06mm Vs 5mm from memory), but will result in high wear rates if you get it wrong!
I used the same calculations for my Schluters, intended to fly on Blackhead Webra 61s (about 1.2 HP, or 900 watts). I came up with 500kV on 6S packs. Again, it flew on this, but was slightly underpowered. I ended up using 580kV.
As a result, my advice would be to use a slightly higher kV rating than you calculate!
As an aside, Phil_G, of this parish, came up with a simple formula for conversions as being 100 watts per cc of engine capacity! This agrees very closely with my figures, and makes for a very simple calculation! Moreover it works for helicopters just as well as it does for fixed wing! Cheers, Phil!
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Pete
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Martin
- Posts: 745
- Joined: 16 Feb 2018, 14:11
- Location: Warwickshire
Re: Rotaire Tyke
Probably the imperial belts are 5.08 mm pitch. One inch is 25.4 mm (that's the official definition of an inch, nowadays) so 5.08mm is exactly five teeth to the inch.
You get the same problems with electrical connectors for PCBs - most are spaced based on inches - often ten to the inch, so 2.54 mm spacing - but occasionally you come across metric connectors with a 2.5 mm spacing. They work okay for short lengths, but when you get connectors more than eight or ten pins long, the inaccuracies build up, and the connectors won't fit.
You get the same problems with electrical connectors for PCBs - most are spaced based on inches - often ten to the inch, so 2.54 mm spacing - but occasionally you come across metric connectors with a 2.5 mm spacing. They work okay for short lengths, but when you get connectors more than eight or ten pins long, the inaccuracies build up, and the connectors won't fit.
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Pchristy
- Posts: 417
- Joined: 16 Feb 2018, 13:57
- Location: South Devon, UK
Re: Rotaire Tyke
Ooops! I was 0.02mm out!
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Pete
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Pete
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davejones
- Posts: 22
- Joined: 16 May 2022, 10:06
- Location: Hervey Bay Australia
Re: Rotaire Tyke
Post deleted
Last edited by davejones on 26 Jan 2023, 08:43, edited 3 times in total.
Dave Jones
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Pchristy
- Posts: 417
- Joined: 16 Feb 2018, 13:57
- Location: South Devon, UK
Re: Rotaire Tyke
That's a good start! It doesn't look far out.
I don't know how much experience you have with fixed-pitch helis, so forgive me if I'm stating something you already know - it might benefit other readers!
It is very tempting to over-pitch them! They should be hovering at around 60-75% throttle, and NOT have a rocket like climb at full bore. If it climbs too fast at full throttle, you will have a LOT of trouble getting it down in any sort of breeze. You have to throttle back so far that the headspeed decays to the point you lose cyclic control.
On my i/c powered Larks, I often run out of forward cyclic in a breeze. As you throttle back for the approach, the nose rises on its own, often requiring full forward stick to keep it down. If you run out of forward stick, the only option is to open up and go around.
Its something you don't find out until you start flying circuits, but the best guide is to ensure that you are hovering above 50% throttle.
Best of luck!
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Pete
I don't know how much experience you have with fixed-pitch helis, so forgive me if I'm stating something you already know - it might benefit other readers!
It is very tempting to over-pitch them! They should be hovering at around 60-75% throttle, and NOT have a rocket like climb at full bore. If it climbs too fast at full throttle, you will have a LOT of trouble getting it down in any sort of breeze. You have to throttle back so far that the headspeed decays to the point you lose cyclic control.
On my i/c powered Larks, I often run out of forward cyclic in a breeze. As you throttle back for the approach, the nose rises on its own, often requiring full forward stick to keep it down. If you run out of forward stick, the only option is to open up and go around.
Its something you don't find out until you start flying circuits, but the best guide is to ensure that you are hovering above 50% throttle.
Best of luck!
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Pete
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davejones
- Posts: 22
- Joined: 16 May 2022, 10:06
- Location: Hervey Bay Australia
Re: Rotaire Tyke
No forgiveness required. All good information and the more out there the better. You're right about the breeze affecting fixed pitch heli's. The slightest puff of a gust has the Tyke climbing really quickly.
I've never flown circuits with a fixed pitch heli but learnt to hover on a friends heli-baby many years ago.
Pitch on the Tyke was set using a pitch gauge supplied with the original kit. Measured at +7 deg on the blades flat bottoms.
Dave
I've never flown circuits with a fixed pitch heli but learnt to hover on a friends heli-baby many years ago.
Pitch on the Tyke was set using a pitch gauge supplied with the original kit. Measured at +7 deg on the blades flat bottoms.
Dave
Dave Jones