Active engine shutoff (IC)

[Kim Mortimore]

Following up on the very entertaining "Active engine control" discussion, a humbler and simpler engine control application might be active engine shutoff at the desired time, with an electronic or mechanical timer.  Maybe it's possible to eliminate the sometimes esoteric matter of calculating fuel volume for changing atmospheric conditions, along with overruns and underruns (and the crashes that sometimes result from the former) while paying only a small weight penalty? he asked.   

If anyone is using timers now, I'm haven't heard of it.  Is it because the R&D has already been done and timers found ineffective/unreliable, or is this an area that hasn't been investigated much and could be worth trying?  IIRC they are not illegal in AMA competition. 

[Tim Wescott]

A Will Hubin timer, a servo, a battery -- presto!  A timer.

I don't know how much a Hubin timer weighs, but it can't be too much.  A servo will set you back 1/4 of an ounce, and a 100mAh LiPo doesn't weigh much (assuming that you get a servo that'll work on 3.7V, and that Will's timer works at that, too).

[Howard Rush]

If you don't care about using it in a contest, you can just use a little RC rig.  Otherwise, if you're sure it's not more trouble than it's worth, I can add some interesting features like cutting the engine when the lines break or when you let go of the handle or when the lines go slack.  The actuator is much lighter than an RC servo, too.  It works with a 6-gram AAA cell.  I'll show you next weekend.

[Tim Wescott]

I'll show you next weekend.

Could you post pictures?

I considered things you could do with much less weight than the system that I proposed -- I was thinking more on the lines of "what can you do with the least hand work?"

For that matter -- do you know what the situation is vis-a-vis rules, both in the US and internationally?

In spite of spawning the active control thread, I kinda like the 'just measure the fuel out' idea, although after I over (or under) run at a few contests I may change my mind.

[Howard Rush]

Here's a picture.  Your homies made the circuit board.

I made this as an electronic shutoff for combat model flyaways. I haven't paid attention to the current stunt rules.  I think it's legal, but if were up to me, I'd outlaw any electronics. 

[Brian Hampton]

Long ago before everyone started getting uptight about such things I used a free flight DT timer. From memory it went to 10 minutes so I'd set it to 6 minutes. It was the type that used a small wire clip that released at the set time. I put a T piece in the fuel line with some soft tubing that was clamped shut under the release wire and at the appropriate time the wire would release, the tube would open up and the engine would almost instantly stop because it could only draw air.

[Howard Rush]

That is certainly a better way to do it.

[Kim Mortimore]

Do you mean better than the mechanical flea fright DT timer, or better than the wire and tubing shutoff mechanism Brian described?

[Howard Rush]

I meant that a mechanical free flight timer that opens a leg to a T in the fuel tube is better than an electromechanical device.  It's better than my electromechanical device, anyhow.  For a combat flyaway shutoff, I think the electronic device has merit. 

[Howard Rush]

flea fright

Wild Bill lives on.

[Greg McCoy]

I think it would be a cool part of the launch ritual to light a timer fuse.

[Tim Wescott]

Because the little boy in me can't see an ant hill without wanting to stir it with a stick:

I think it's legal, but if were up to me, I'd outlaw any electronics.

No electronics if you're running IC, or no electric motors?

[Howard Rush]

You'd be allowed to use a battery to light your glow plug on the ground.  That's it.  Motors and their ilk would be prohibited.

[Tim Wescott]

You'd be allowed to use a battery to light your glow plug on the ground.  That's it.  Motors and their ilk would be prohibited.

It's interesting that you should say that.  I think that electrics have been the salvation of RC flying -- say whatever else you may, some kids in a park playing with an electric plane are going to get less negative attention from neighbors and officialdom than the same kids with the same plane with a noisy IC engine.  Since it's today's kids that are going to be the 'troops' in our clubs when we're in our 70's or 80's, I want them to have as broad and as happy a modeling experience as possible.

[FLOYD CARTER]

The first problem one confronts with sending signals down the control wires is that the lines are almost always twisted and not insulated.  Therefore, going back to my antenna theory classes, it is possible to send a signal through the lines, both lines simultaneously.  The "return" is ground, or in this case, the atmosphere of the surrounding universe.  For low RF signals, (say about 1 MHz) this is called "Permittivity of Space" and is equal to 377 Ohms equivalent. Note that no RF signal is intentionally "transmitted" through the ether, thus complying with the rule.

This would require a transmitter at the handle end, and a sensitive receiver in the plane.  Once a signal is received, it is an easy matter to operate a servo or other electromagnetic device.

This system would be more sensitive closer to the ground, where capacitive coupling effects would increase the received signal.

Floyd

[Tim Wescott]

The first problem one confronts with sending signals down the control wires (snip)

I think Kim is asking about timers -- certainly that's the question I'm answering.

One could do this with a three-wire system, and just hold full throttle for the whole flight and only release it at the end (or just use an air bleed shut off like Howard mentioned).  Then you'd get a "stunt run", you wouldn't have an automatic shut off, etc., etc.

An acquaintance of mine tells about going to a stunt contest with his all-around ship, which had an OS Wankel in it and a three-line control system.  He flew a couple of maneuvers, decided it was running too lean, landed, walked to the plane and adjusted the still-idling engine, then walked back to the handle and completed his flight.

He said he only had one judge that actually watched the rest of the flight, as the other two were looking through the rule book to see if he could actually do that.

[Kim Mortimore]

I think it would be a cool part of the launch ritual to light a timer fuse.

LOL.  We have some purdy durn good comedians in stunt.  That would make quite an impression on the judges, and probably add
"open fires" to the list of things prohibited in the next rules cycle.  

Wild Bill lives on.

I had the privilege of corresponding with Mr. Netzeband late in his life.  He didn't know me from Bubba Bellcrank, but treated me as if we'd been good buddies for years.  What a delightful, inventive gentleman, a fine example for us all.  May he rest in peace and his memory live long.  

You'd be allowed to use a battery to light your glow plug on the ground.  That's it.  Motors and their ilk would be prohibited.

Given the present climate in stunt, Mr. Howard gots guts.  

[Howard Rush]

The first problem one confronts with sending signals down the control wires is that the lines are almost always twisted and not insulated.  Therefore, going back to my antenna theory classes, it is possible to send a signal through the lines, both lines simultaneously.  The "return" is ground, or in this case, the atmosphere of the surrounding universe.  For low RF signals, (say about 1 MHz) this is called "Permittivity of Space" and is equal to 377 Ohms equivalent. Note that no RF signal is intentionally "transmitted" through the ether, thus complying with the rule.

This would require a transmitter at the handle end, and a sensitive receiver in the plane.  Once a signal is received, it is an easy matter to operate a servo or other electromagnetic device.

This system would be more sensitive closer to the ground, where capacitive coupling effects would increase the received signal.

Floyd

Dean Pappas and Alexander Prokofiev have made systems like this: Dean's for retracting landing gear, Alexander's for F2D shutoffs.  I think rules were overlooked in the latter's case, because everybody thought it was for the good of the sport.

[Jim Thomerson]

Racers use a spring loaded shut off tripped by full down.  I have a Seelig timer somewhere which would also do the job.  There was Sonny Mullins "San Antonio Rose" with Hornet 60 at one of the early VSC's.  It used a mechanical timer shutoff.  My son won Senior C free flight at the 1983 Nats using a fireworks fuse engine shutoff. 

[phil c]

Dean Pappas and Alexander Prokofiev have made systems like this: Dean's for retracting landing gear, Alexander's for F2D shutoffs.  I think rules were overlooked in the latter's case, because everybody thought it was for the good of the sport.

According to Alex his shutoff uses audio frequencies.  The  Rx in the plane listens for a particular frequency(I think he said it checks 10 different freqs about 1Khz. apart.  He has some method for setting which freq it listens for.  When the noise goes away, either because the lines break or you turn it off at the handle a battery operated valve shuts the fuel line off.

[jim ivey]

   I like the lighting the fuse idea and at the end of the flight the airplane explodes . On a more serious note theres a way to adjust fuel levels like we used on the hornet timer tanks. In botom half of the tank we inserted or removed b-bs to adjust the amount of fuel available to the engine. you could put an extra larger tube in your tank that you could insert plastic beads in for less fuel or remove to for more. Get my drift ? jim                                                                                                       PS  come to think of it check to see if those very small plastic beads will fit throgh the tubing ib your tank. hmmmmm  fishing line also would work as for needing more fuel, larger tank.  jim   

[Paul Smith]

According to Alex his shutoff uses audio frequencies.  The Rx in the plane listens for a particular frequency(I think he said it checks 10 different freaks about 1Khz. apart.  He has some method for setting which freq it listens for.  When the noise goes away, either because the lines break or you turn it off at the handle a battery operated valve shuts the fuel line off.

I saw the Alex gizmo.  Under his own (or somebody with the skeels), it worked OK a few times.  The drawbacks are:

Requires a battery-powered device onboard the model.
Depends on battery power to pinch the line.
Will not pinch the line if the battery is weak.
Is entirely fail-DANGEROUS, not fail SAFE
Relies on faith to believe that it really sends signal through lines, not air.

All said, there would be nothing wrong with using it end a stunt run.  The original offering price was something like $645 for two handles and four airborne units.

[Howard Rush]

Baldardash.  Having a charged battery onboard is no more a problem than having your engine mount bolts tightened.  You can run an end-to-end test to demonstrate that the shutoff works and the battery is charged.  Such a ground test is more indicative that an electronic shutoff will work than it is that a mechanical shutoff subject to aerodynamic drag will work.  Your last two statements are bereft of meaning.  It looks like you just put them there to pad your list. 

The thing that I think most distinguishes electronic shutoffs from mechanical ones is that the mechanical ones rely on keeping springs and such claptrap in tolerance, whereas the electronic ones use resistors and condensers that are more predictable. 

[Kim Mortimore]

.....The thing that I think most distinguishes electronic shutoffs from mechanical ones is that the mechanical ones rely on keeping springs and such claptrap in tolerance, whereas the electronic ones use resistors and condensers that are more predictable.  

It looks like Howard may be right.  Imagine that.  I emailed Hank Nystrom at Texas Timers and asked him what he thought of the idea of trying his DT timer in conjunction with his remote pinch-off mechanism normally used with the engine timer (a whopping 22 grams all up).

He replied, "Since there is a vibrating speed regulator, I would expect the speed of my DT timer to vary compared to sitting still on the ground (or presumably floating engine-off in a F/F plane). One would need to watch the axis of vibration to be sure centripetal forces did not stop it. For darn sure you would need to keep all the gallons of burnt oil out of the timer works (which one would want to do with an electronic timer too, of course). That would really mess it up."

Since the engine is running for only a few seconds of a DT timer's duration in a F/F power plane, and the tolerance for timing error is large, it appears there was no need to consider vibration as a major factor when designing a mechanical DT timer.  The tolerance listed for the Texas timer is +/- 5 seconds for maxes 5 minutes and under, going up from there.  Not really bad, but not great.

If occurs to me that the heart of an electronic stopwatch is surely light and small.  Possibly a programmable unit of that general sort combined with the applicable parts of a Rush electronic combat shutoff, and a Texas Timers remote pinch-off (1.9 grams with cable), to keep the works away from fuel and the limited available room in the nose of a stunt plane, could be worth the experiment.  Howard, we can talk next weekend as you suggested if my health allows me to attend.

[Tim Wescott]

If occurs to me that the heart of an electronic stopwatch is surely light and small.

As are the parts of an electronic kitchen timer, which is designed to count down and then do something (like go beep).

By the time you'd adapted it, though, you may find that you should have just built something from scratch.

[Kim Mortimore]

As are the parts of an electronic kitchen timer, which is designed to count down and then do something (like go beep).

By the time you'd adapted it, though, you may find that you should have just built something from scratch.

Yes, that's what I have in mind.  Not very clear in my message. 

[Howard Rush]

This reminds me of the Salter-Rush Electrohonker, which used a kitchen timer to sound an air horn at the end of a combat match.  It worked the first few times, then would let out an asthmatic wheeze at the end of the match period.  I got all the blame.

[jim ivey]

As for the guy in a contest landing adjusting his NV and taking off again. I think when he landed that would have terminated that flight wouldn't It? It would've in my day! My intrest in the throttle, was to slow the plane down on the downside of manuevers, (not to land so i could re-adjust the NV) , though it might have been a good idea on that stuka . Ya know the worst part about that crash! Billy was watching jim                                                                                                                      ps howard i\I still have bills e-mail addy in my hotmail contacts. I cant bring myself to delete him. He was a good friend and flyer I knew him fairly well.                   jim                                     

[Jim Thomerson]

Jim, in OTS, one can make a case that getting on the ground and adjusting the needle valve would be legal.  In reading about British contests in the OTS era, running out of fuel, or whatever, and restarting was common.  The 1948 British stunt schedule has maybe almost twice as many maneuvers as our OTS schedule. 

[Shultzie]

While talking to Joe Dill this weekend about his winter SnowBird flight to join the rest of our NW Birdeezzzz' in the wintertime sunny Tucson south lands...

our conversation turned to CLPA fuel shut off concepts...and ended up talking about the retracts that he has planned on his new Harold Price Crusader that he has almost ready for final finishing and paint.

NOT TO KIDDYKNAPPY this post...our conversation then turned to his own retract system.

Seems he is researching a  retract system...that utilized the stunt engine's "noise factor" that once is tripped...allows for about 10 sec. or so to allow for take off before the signal is sent to retract the gear for flight.
Then after the engine quits...the sudden lack of engine noise...then sends a signal that extends the gears for landings?

(This sound like a fairly good and SOUND idea?)
 Does anyone have information on just who, what n' when this system might have  been used in the past?

[Tim Wescott]

While talking to Joe Dill this weekend about his winter SnowBird flight to join the rest of our NW Birdeezzzz' in the wintertime sunny Tucson south lands...
...
NOT TO KIDDYKNAPPY this post...our conversation then turned to his own retract system.

Not to kidnap the thread, I've started one called "Retracts" and quoted you there -- with my own lame attempt at an answer.

http://stunthanger.com/smf/index.php?topic=19175.msg177117#msg177117

[Shultzie]

Not to kidnap the thread, I've started one called "Retracts" and quoted you there -- with my own lame attempt at an answer.

http://stunthanger.com/smf/index.php?topic=19175.msg177117#msg177117

Thanks gang...
I think Joe also mentioned that our Bart Klapinski...has  been researching both a retract gear concept as well as an extremely light weight and positive engine cut off system.
No really sure if both systems...(now that I thimkeedle' about it) are to be used in the same CLPA model???
Humm?
just a couple of shots I shot of young Bart waaay back at my first 67 Nats...for the memories!
 WOW! TIME FLIES!

[john e. holliday]

Bart had the retracts working at VSC this year.  Can't remember the name of the plane, but it was awesome.   

[Hoss Cain]

I think Kim is asking about timers -- certainly that's the question I'm answering.
//snip//
He said he only had one judge that actually watched the rest of the flight, as the other two were looking through the rule book to see if he could actually do that.

As long as the model did not move it should have been legal.
"The flier will retain the control handle in his hand at all times during which the model is in motion."

[Balsa Butcher]

A far as retracts go, there is a NorCal flier who is on his second stunt plane using the timer/microphone set-up that Alpha Dog (among others)  pioneered a few years back. It works great. As far as fuel shut-offs go, I'm sure that the technology is there but I've  always considered timing run time via fuel quantity to be an accepted part of the challange of stunt. 

[FLOYD CARTER]

I'm working on a system for retracts.  I'll send a VLF signal via the lines to a "direct conversion" receiver in the plane.  I will define VLF as being "ultrasonic", and not RF, thus avoiding any controversy about "transmitting an RF signal".  Both lines will carry the same signal, with the "return" being capacitive coupling through space.  There are no antennas involved.  Efficiency will be poor, but it is easy to simply increase power at the handle.  The receiver will have very high gain and tuned circuits to reject noise.

I'll report on progress as soon as I have a breadboard system working.  You can contact me directly regarding this project at my e-mail.  floydecarter@gmail.com

Floyd

[FLOYD CARTER]

I should mention that I have been flying a P-51 with retracts. The electronics is a Jomar unit designed by Joe Utasi.  It detects engine noise with a small microphone, and drops the gear when the engine quits.  Gear "up" is on a timer (about 10 sec.) after the pit crew pushes the "go" button.  It works OK, but I would prefer to actuate the gear up and down when I want, and not when the engine quits.

Floyd

[Mark Scarborough]

Floyd, I am horrbile at following directions so I am not going to email you about this, just wanted to say I am following your developements with great interest. I love semi scale stunters, retracts would just complete the picture for me!

[Peter Ferguson]

You'd be allowed to use a battery to light your glow plug on the ground.  That's it.  Motors and their ilk would be prohibited.

Keeping with Howards requirements and the original topic I have a vintage solution.

Perhaps we could release a cloth rag at 7 minutes which the stunt flyer attempts to fly through to kill his engine, If he misses it he accepts the consequences.

[RandySmith]

You'd be allowed to use a battery to light your glow plug on the ground.  That's it.  Motors and their ilk would be prohibited.

Keeping with Howards requirements and the original topic I have a vintage solution.

Perhaps we could release a cloth rag at 7 minutes which the stunt flyer attempts to fly through to kill his engine, If he misses it he accepts the consequences.

...or... you could just put 6:15 min of fuel in the tank....after 6:15 the fuel tank would actively kill the motor by staving it to death   


Randy

[RandySmith]

Now that's a great idea! Do the rules allow it? I've understood that the shut-off signal has to go via lines. L

Yes use the force...send the "vibes" down the lines from your hand...to kill the motor...