what is PROPO?

[th3tick]

So, my radio says "JR PROPO". I know this is probably a stupid question, but what is "PROPO"?

John

[cbdane]

So, my radio says "JR PROPO". I know this is probably a stupid question, but what is "PROPO"?

John

This is quite an old term indicating that this R/C control system uses "proportional" control. This means that the rotation of the servos is proportional to the deflection of the control sticks. Seems like an obvious thing since all R/C systems work this way now. Back in the day, though, many systems were pulsed and the control motion was either full throw or none. You flew the R/C aircraft by "blipping" the stick (or even pressing a button) to control roll, pitch, etc.

Interestingly, non-proportional control is still used on tiny, ultra-lightweight indoor flyers in which the servos on flight surfaces are replaced by small electro-magnetic galvo drives.

[Pinecone]

The earliest RC setups used an escapement mechaism. This gave you a sequence of Right - Neutral - Left - Neutral each time you push a button. It was powered by a rubber band wound up. People did crash because they forgot to wind the rubber band.

Then came Reed systems, then had a 3 way switch for each control, if you pushed the aileron switch left, you got full left aileron, then neutral when you released the control. So with a 4 channel setup (modern counting) you had 4 separate switches that you were constantly blipping. This actually worked by sending an audio tone over the RF link and this caused a sympathetic vibration in the proper reed and that made the switch contact to move the surface.

Another way was Pulse Proportional aka wag-wag systems. This had each surface move full left/full right back and forth. As you moved the control stick, the amount of left time and right time changed, so you got proportional response.

Finally came the basis of the systems we use today, the modern Proportional RC setup.

[kamtsa]

The earliest RC setups used an escapement mechaism. This gave you a sequence of Right - Neutral - Left - Neutral each time you push a button. It was powered by a rubber band wound up. People did crash because they forgot to wind the rubber band.

Wow!

Pinecone, have you considered to document this RC history somewhere so it does not get lost?

For example, Wikipedia can be a good place.

Kam

[DavidH]

Wow!

Pinecone, have you considered to document this RC history somewhere so it does not get lost?

For example, Wikipedia can be a good place.

Kam

Don't have to document it. It is already documented at the AMA museum in Muncie,IN. The museum has exhibits and documents explaining the advancements in the hobby for over 70 years.


http://www.modelaircraft.org/museum.aspx

David

[kamtsa]

Don't have to document it. It is already documented at the AMA museum in Muncie,IN. The museum has exhibits and documents explaining the advancements in the hobby for over 70 years.

I would like to read more about the rubberband based servo 'motor' Pinecone mentions (and see pictures if possible) .

Do you have a link for it? I could not find one myself.

Thanks,

Kam

[DavidH]

Here is some pictures of and escapement system from OS. The rubber band was wound up and hooked to the hook you see. This is what provided the power to move the control.

http://www.rchangout.com/gallery/showphoto.php/photo/8724/cat/recent/limit/recent

There was a wound coil with a plunger inside. The electrical pulse on the coil would move the plunger which would release the rubber band to unwind which turned the control wheel.
This was just one channel system. So they were usually used on rudder. One push of the button would allow the rudder to move one direction, two pushes of the button and it would move back opposite direction. The rubber band was turning the wheel the same direction all the time. It was just the way the mechanism was designed that allow it to go opposite direction,

Some more links
http://www.modelsbuzz.com/forums/airplanes/43166-any-old-timers-out-there.html
http://homepages.tesco.net/ada.tippett/Radio7.htm


David

[Pinecone]

Nice shot. I never owned on, even though they were still available at the time. I did have a wag-wag system in a Testor's Cherokee RTF. Single channel wag-wag system, WenMac .049. Foam wing, blow molded plastic fuselage. First RC aircraft that came after me. :) They even had a conversion for that system to turn it into a 3 channel system, 2 channels wag-wag (rudder and elevator) and a multi position throttle.

With escapement you would push the button and as long as you held it you get full rudder deflection. When you released, you go neutral. Push again and you got full rudder the other way.

IIRC there was an advanced system that one push gave, say, right rudder, every time, a double push gave left rudder , every time, so you didn't have to remember what the last rudder direction was.

And believe it or not, you could do aerobatics with these. Push and hold rudder and you would get a spiral down with increasing airspeed, release and the speed would turn into a loop. Speed with rudder again once it straightened out would given a barrel roll.

[kamtsa]

Here is some pictures of and escapement system from OS...

Thanks David. Very interesting.

I wonder how people will look 50 years from now on our toys.

Tal

[Pinecone]

Well, really the only change from the late 60s to now has been computer radios, FM, PCM, and now 2.4 GHz. Some changes to the actual channels on 72, narrow band Tx and Rx. But really those are all pretty much modifications to the basic setup.

But my first propo radio, a HeathKit version of a Kraft 5 channel is pretty much the same as today. PPM modulation on 72 MHz.

[infanterene]

I thought the Propo stood for Ko Propo. JR and Ko are sister companies.

[WiscHeli]

JR started years ago as circus circus Radio i beleive

[DavidH]

Nope Circus was the importer of JR radios. Circus was a hobby shop/distributor in Las Vegas. The JR radios had a Circus Hobby label on it. Bill Bennett owner of the Circus Circus casino/hotel at the time owned Circus Hobbies. Bill was also the person that started the TOC airplane event in Las Vegas. The RC field out on the edge of town is Bill Bennett Field. That is where the event was held. Bill died a few years ago.

David

[terrabit]

The earliest RC setups used an escapement mechaism. This gave you a sequence of Right - Neutral - Left - Neutral each time you push a button. It was powered by a rubber band wound up. People did crash because they forgot to wind the rubber band.

Then came Reed systems, then had a 3 way switch for each control, if you pushed the aileron switch left, you got full left aileron, then neutral when you released the control. So with a 4 channel setup (modern counting) you had 4 separate switches that you were constantly blipping. This actually worked by sending an audio tone over the RF link and this caused a sympathetic vibration in the proper reed and that made the switch contact to move the surface.

Another way was Pulse Proportional aka wag-wag systems. This had each surface move full left/full right back and forth. As you moved the control stick, the amount of left time and right time changed, so you got proportional response.

Finally came the basis of the systems we use today, the modern Proportional RC setup.

Jesus H Louise! What planet are you from? And, how the heck do you know all this stuff? You must be a voracious reader. I agree with my fellow freakster, you should write a book, or so.

[Pinecone]

I was learning about RC during the transition time. :)