Babcock Mk V Escapement

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mlbco
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Joined: 16 Feb 2021, 06:12

Babcock Mk V Escapement

Post by mlbco »

Listed below are 2 videos that show my 25% enlarged Top Flite Roaring 20 with a Babcock MkV escapement providing rudder and elevator control. An Arduino micrcontroller creates the pulse sequence from a standard 2.4GHz RC uplink. The brushless electric motor throttle control is on a conventional RC channel and is proportionally controlled. I built the model to experiment with the Babcock Mk V, an escapement I have never flown before. I've gotten to the point where I can fly this model almost as well as a proportional 3 channel. The escapement operates reliably with the Arduino pulse generator and the timing adjusted for the nominal range of the rubber motor winds. The code and electronics are my own but nothing very fancy, just things I hacked together.

Operation of the escapement is shown in the 2nd half of the first video.

Steve


mlbco
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Joined: 16 Feb 2021, 06:12

Re: Babcock Mk V Escapement

Post by mlbco »

Phil_G wrote: 16 Feb 2021, 17:16 Love it Steve :)
Over here we had the Elmic range of escapements, we could only have one elevator direction, kick-up or down, but not both.
I never saw a four-function Babcock until Shaun showed me his test rigs.
Do you count the number of commands and use that to change the pulse timing as the rubber runs down?
I remember that was a big problem with the Macgregor Codamac pulser.
Having said that, nobody in our club bothered with an elevator :D
Great videos, thanks for posting
Phil
Phil,
I can get close to 600 winds on the escapement and at least 2/3 of the winds are useful with correct timing, so I've never hit the portion where the rubber unwinds to the point where timing is lost. The Roaring 20 has a long length in the fuselage for the escapement rubber and that was a factor for why I chose this model. I was able to set the software timing on the pulses to work for roughly 400 commands per winding.

I'm issuing 1-2 commands per second when flying close in. This set-up lets me bank hard in a turn and then alternating between rudder and up-elevator commands to hold a very tight, low altitude 360 around myself.

Thanks,
Steve
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Shaun
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Location: West Yorkshire

Re: Babcock Mk V Escapement

Post by Shaun »

Brilliant Steve..

You can't beat the sound of a clattering escapement in flight.

The system I have used 2 cascaded Babcock escapements with 2 rubber drives. Not as compact as your hyper compound version.

What's your next project?

Cheers,

Shaun.
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Wayne_H
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Re: Babcock Mk V Escapement

Post by Wayne_H »

Very nice Steve :)

This is the first time I've seen a Babcock escapement actually operating having never seen one 'in the flesh'. I love the sound of it doing its thing in flight!

Now I have a better appreciation for why they appear on so many plans from the period ;)

Thanks for sharing
Cheers,

Wayne
Once a Retrobate, always a Retrobate............ ;)
MJF
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Joined: 12 Jun 2018, 15:22
Location: Ontario Canada

Re: Babcock Mk V Escapement

Post by MJF »

Great project Steve.
Really neat to see a model flown with an escapement today.
Your Roaring 20 scaled up looks like the perfect size for flying off the grass and being able to see it in flight.

Enjoyed your videos too.


Mike F
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iflylilplanes
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Re: Babcock Mk V Escapement

Post by iflylilplanes »

Great to see old gear working, nice video, can you do a loop?
I've got a Mk V in my collection, missing the odd shaped rudder and elevator bits, I have drawings and the brass to make them, one day.
Cheers,

Dave
mlbco
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Joined: 16 Feb 2021, 06:12

Re: Babcock Mk V Escapement

Post by mlbco »

Shaun wrote: 16 Feb 2021, 19:00 ...
What's your next project?

Cheers,

Shaun.
No ideas yet, my interest in old RC equipment is cyclical. I just built 2 models using escapements so I might need to switch back to more modern stuff. I do have a sizeable stash of old kits and motors (who doesn't!) that needs some attention, but I keep scratch building instead of consuming the old kits. I am happy to have these problems.

Thanks,
Steve
mlbco
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Joined: 16 Feb 2021, 06:12

Re: Babcock Mk V Escapement

Post by mlbco »

iflylilplanes wrote: 17 Feb 2021, 01:32 Great to see old gear working, nice video, can you do a loop?
Haven't tried one yet, but I suppose I should. I've been intentionally keeping the model low just in case the controls act up, that way I can cut throttle and land in the field. Everything has been reliable for the last 10 flights so I should be able to go high and try a loop. My favorite maneuver is still flying a low, tight, 360 around myself and listening to the escapement churn away.

Thanks,

Steve
mlbco
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Re: Babcock Mk V Escapement

Post by mlbco »

Here's a video showing how I can fly tight circles around me by alternating between rudder and elevator commands. If you turn up the volume you can hear the escapement cranking away with each command.

The trickiest part is to make sure and wait for the escapement to return to neutral before giving the next command. Since I'm using a modern radio transmitter, it's always tempting to just move my thumb quickly like a standard servo controlled model, but the escapement only accepts one command at a time and there is a delay before you can successfully send another command.

Steve
Tobe
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Re: Babcock Mk V Escapement

Post by Tobe »


This is exactly what my late father tried to teach me when he gave a better home to my Guided Mite! Full story included...some people are blessed with "Magic thumbs"
Attachments
Zebra.pdf
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Cheers,

Tobe
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