Twin Engine Synchro  
View related threads: (in this forum | in all forums)

Tower Hobbies
Enter up to 4 keywords or Tower stock numbers
Logged in as Guest



Users viewing this topic: none
  Printable Version
       

All Forums >> RC Airplanes >> Twin & Multi Engine RC Aircraft >> Twin Engine Synchro
Page: [1] 2   next >   >>  

Login
Message << Older Topic   Newer Topic >>
Twin Engine Synchro - 2/11/2003 9:43:47 AM   
djsmith1000


 

Posts: 9
Joined: 2/11/2003
From: Howell, MI, USA
Status: offline 		Hello All,

I am developing an engine synchronizer for twins, and would like feedback from anyone interested in such a product. This device will utilize state of the art electronics, and will be easy to install and very versatile.

If you have any options that you would like to see on a synchronizer, especially regarding engine failure modes, please respond with them, as they may very well be integrated.
I would like to hear from everyone interested in this product so that I can determine initial production quantities. Please spread the word.

Thank you
Daniel Smith

email comments/responses to

[email]Daniel_Smith@juno.com[/email]
       Post #: 1

Twin Engine Synchro - 2/11/2003 12:58:15 PM   
William Robison



Posts: 20269
Joined: 11/10/2002
From: Mary Esther, Florida, FL, USA
Status: offline 		Smitty:

I wont try to give you a flowchart, but here’s what I’m working on.

Inputs to the system are throttle and rudder signals from the rx, and an rpm signal from each engine.

Output is separate signals to the throttle servos.

If it does not get both rpm signals it passes the receiver throttle signal through to the throttle servos with no alteration.

Both rpm signals are sent to counters, the difference is divided by two, added to the pulse time for the slower and subtracted from the faster, with the rx throttle pulse time being the center.

>This eliminates the “Master/Slave” of the EMS system, and therefore prevents the slave engine starting at full throttle, and takes care of any worries about “Stronger” and “Weaker” engines – self correcting.<

>At this point we have the ideal synchronizer for straight flying, but since we want a little fancy, we add the differential command.<

Check rudder pulse time. If greater than 1.30ms and less than 1.70ms, OR if rx throttle pulse time greater than 1.5ms ignore rudder signal.

Check rudder pulse time. If less than 1.30ms or greater than 1.70ms, AND if rx throttle pulse time less than 1.5ms add (throttle time – 1ms)/2 to opposite throttle pulse time.

>This gives differential throttle for taxi realism, and extreme maneuvers in flight, while ignoring normal rudder movement, and still keeping the engines in tune otherwise. Also, if the engines are at 50% power or greater the rudder has no effect. And by basing the added pulse time on the throttle signal we can vary the amount of engine acceleration.<

I can make this work on my P-3 computer, but I haven’t managed to get it inside a small plane. And it’s my ideal sync system.

Hope this helps you.

Twin engines in sync,
. That's best, I think.

Bill,

_____________________________

Real Airplanes have Two Engines
AMA 25139 - More than 40 years.

(in reply to djsmith1000)
       Post #: 2

Twin Engine Synchro - 2/11/2003 6:45:41 PM   
Baldeagle


 

Posts: 1476
Joined: 2/2/2002
From: Lakeside, AZ, USA
Status: online 		Daniel
Put me on the list for one. Thanks

_____________________________

Rich

(in reply to djsmith1000)
       Post #: 3

Twin Engine Synchro - 2/16/2003 10:26:42 AM   
djsmith1000


 

Posts: 9
Joined: 2/11/2003
From: Howell, MI, USA
Status: offline 		Rich and Bill,
Thanks for your input. I really appreciate your feedback. I am about halfway through the programming phase. I will keep you updated on the progress.
Dan

(in reply to djsmith1000)
       Post #: 4

Sounds good - 2/16/2003 9:09:15 PM   
elmshoot


 

Posts: 568
Joined: 12/27/2001
From: Nashville, IN,
Status: offline 		I have experience with the EMS and am very happy with its performance. But if you can come in at the same price with the added features put me down for one.
Sparky

(in reply to djsmith1000)
       Post #: 5

Twin Engine Synchro - 2/16/2003 10:28:19 PM   
Rudeboy



Posts: 3256
Joined: 12/9/2002
From: Bejing, BELGIUM
Status: offline 		Bill, are you going to market that design of yours?

If so, let us know when and where... I would really be interested in yours...

(in reply to djsmith1000)
       Post #: 6

Twin Engine Synchro - 2/16/2003 10:55:11 PM   
William Robison



Posts: 20269
Joined: 11/10/2002
From: Mary Esther, Florida, FL, USA
Status: offline 		Mannerless One:
[QUOTE]Originally posted by Rudeboy
Bill, are you going to market that design of yours?
If so, let us know when and where... I would really be interested in yours... [/QUOTE]
This is a low priority item for me, cobbled up a "Breadboard" prototype, ten (?) chips, 12 volt supply, running time less than five minutes with 1100 mah battery pack. It was also MUCH too heavy to use in anything less than giant scale and the cost also was totally unreasonable.

Partial list of chips:
CPU - 1802
RAM - 2114 x2
CMP - 7485 x2
ROM - 6116
REG - 7805
This is from memory, I did this several years ago and set it aside. Might have some numbers wrong. But I know I was using the RCA 1802 and the 2114 static ram.

That's why I was very pleased to see Dan Smith working on one, If he does it my way, and does it well, I'll buy five or a dozen from him and save myself the development bothers. Provided, of course, the price is reasonable.

The EMS units work, and they work very well, I am using them now. But they don't work the way I would like them to.

And thanks for the interest.

Differential thrust AND sync,
. With Heaven you have a link.

Bill.

_____________________________

Real Airplanes have Two Engines
AMA 25139 - More than 40 years.

(in reply to djsmith1000)
       Post #: 7

Twin Engine Synchro - 2/17/2003 12:51:07 AM   
Rudeboy



Posts: 3256
Joined: 12/9/2002
From: Bejing, BELGIUM
Status: offline 		I guess this is one of these things... the proper parts... the proper programming... working out a design that draws very little current... not all that easy...


That EMS that was mentioned in earlier posts, where can that be found?

(in reply to djsmith1000)
       Post #: 8

Twin Engine Synchro - 2/17/2003 1:28:25 AM   
William Robison



Posts: 20269
Joined: 11/10/2002
From: Mary Esther, Florida, FL, USA
Status: offline 		Uncouth:

Memory coming back a bit, my rig used only one 7485 comparator, but it did have two 4020 counters in it.

RPM pulses went into the counters, they fed the comparator, the comparator had three output conditions: A=B, A>B, and A
Regards the current drain I was trying to convert everything to Cmos, that would remove the need for voltage regulation also. Dan, you're welcome to note this too. The RCA 1802 is Cmos.

Here's the source for the EMS unit.

http://www.emsjomar.com

Last one I got was $90. They work very well. But if you jam the throttle the engines will go out of sync for a moment, it takes about 1/4 to 1/2 second to catch up. Almost too short to notice, but going from full to idle you'll see the plane wiggle a bit. From idle to full the engines usually have more difference in lag times than the sync unit. So long as you work the throttle smoothly you'll never see the delay.

Twins in sync,
. You're in the pink.

Bill.

_____________________________

Real Airplanes have Two Engines
AMA 25139 - More than 40 years.

(in reply to djsmith1000)
       Post #: 9

Twin Engine Synchro - 2/17/2003 2:53:45 AM   
djsmith1000


 

Posts: 9
Joined: 2/11/2003
From: Howell, MI, USA
Status: offline 		I dont think current drain will be a problem with the components I am working on. I think I will be able to complete all operations with one small microcontroller. Surface mount technology may be used to keep packaging small, without limiting options. I have yet to decide on which options to include, like the differetial throttle/rudder option Bill proposed. I would like feedback from other people on this to see what the demand for such options is.
Dan

(in reply to djsmith1000)
       Post #: 10

Twin Engine Synchro - 2/17/2003 3:02:59 AM   
Rudeboy



Posts: 3256
Joined: 12/9/2002
From: Bejing, BELGIUM
Status: offline 		The throttle-rudder coupling may be overkill on a small sport model, though still very useful...

On a large scale airplane however... that would look and sound very smart. It adds a scale note...

(in reply to djsmith1000)
       Post #: 11

Twin Engine Synchro - 2/27/2003 8:44:43 AM   
Donnie


 

Posts: 22
Joined: 12/16/2001
From: Oran, MO, USA
Status: offline 		I would be interested in one also,Keep me posted when you
get it finished.

(in reply to djsmith1000)
       Post #: 12

Twin Engine Synchro - 3/4/2003 8:24:07 AM   
djsmith1000


 

Posts: 9
Joined: 2/11/2003
From: Howell, MI, USA
Status: offline 		Sorry about lack of updates. I have had computer trouble. It is costing me quite a bit of time.
Dan

(in reply to djsmith1000)
       Post #: 13

Twin Engine Synchro - 3/5/2003 1:51:06 AM   
JL1


 

Posts: 471
Joined: 2/10/2002
From: Mason, MI, USA
Status: offline 		djsmith, I am interested in your project. I live "next door" down by Mason and have a couple of twins we could test it on :-)
Jon L.

(in reply to djsmith1000)
       Post #: 14

Twin Engine Synchro - 3/13/2003 9:29:55 PM   
nospel


 

Posts: 21
Joined: 3/11/2003
From: plant city, FL, USA
Status: offline 		Dan,

i have cought the twin bug and i would like to see what you come up with for a price point on these. I was going to use a EMS system on board but bill has a point that coupling the ruder in for under half throtel to help out on the ground would be a very nice feature.

What are you programing them in. I work as a programer and write in a verity of languages. went to school doing embeded systems programing on motarola hc11 and 56k series DSP's Would love to help this get off the ground.

lee

_____________________________

live to fly,
fly to live.

(in reply to djsmith1000)
       Post #: 15

Twin Engine Synchro - 3/14/2003 3:35:05 AM   
Metal bender


 

Posts: 15
Joined: 3/11/2003
From: Conroe, TX
Status: offline 		I have a Safety Sync. I don't think they're made any more. It is a bear to set up but works great when adjusted. You only have to adjust it once. The feature I like best is if you lose an engine it pulls the other back to idle. You pull your throttle stick back to idle and then you can advance the good engine to an RPM you set. If you go past that position the engined goes back to idle. There is also a lead for a strobe light or gear switch. When an engine dies the light comes on or the gear goes down. I haven't tried that mode yet.

(in reply to djsmith1000)