Author Topic: Fuel Shutoffs for F2d (Read 5049 times)

Paul Smith · « **on:** August 04, 2008, 05:03:01 PM »

I've been watching the F2 results very closely on this and other web sites and also via some private E-mails from the principles.

I was in this event since eight years before DAY ONE. I was out after 1990 due to a fruit basket rules change that wiped out my whole stash. I got back in again for the 2008 season and got all-new 2008 stuff, which enabled me to repeat my 1974 3rd place at The NATS.

The 2008 WC had 92 Combat entries, more than Stunt and more than Speed and Racing combined. I have no doubt that the destructive "shutoff rule" was pushed through by the A-B-C old school junta as a way of cutting D down to size. They've never liked Combat from the start, especially the Team Racers, the former center of attention. In the view the high class elites, Combat brings in a brand of rifraf they'd prefer not to have around.

But Combat flyers are more dedicated than they imagine. We've survived 10% nitro, rediculous downtime scoring, 4 mm venturis, mufflers, and a rule book that's a close second to the IRS code.

They had about 40 entries in the last two US Team Trials.
For the last two cycles, Canada has had only four active flyers. In lieu of TT, they had a group discussion, picked a team, beat the USA, and took home team Bronze.

The Ukraine won this year's WC, which is fitting, since they design and build the world's equipment. Maybe the fuel shutoff will provide an opening for some ingenuity and mechanical creativity. Something more than bolting FORA's to Vikos. No doubt this rule will weed out some of the weakies, but the hard core will remain.

Scott Jenkins · « **Reply #1 on:** August 05, 2008, 02:14:57 PM »

Paul,

First of all what is the problem, and second you do not have your facts straight about the number of entries in F2A, F2B, and F2C The total numbers of entries for those three events was 183 roughly twice the number of entries in F2D. There are a few Team Racers who have quite sucessfully flown F2D, Tom Fluker past world champion comes to mind at present, furthermore I know of no one in American F2C competition who has ever turned their nose up at any combat flyer a good portion of us like to fly combat too.
The rules made by the sanctioning committee were made to keep people safe. Any airplane flying over 100 mph is a danger to everyone. If you want to lay blame for the current rule set at someones feet, look to the East we have only one vote and while the powers that be may have sided with the rest of the committee it does not mean they were happy about it unless of course it was in the interested of safety. F2C to me has never been the center of attention F2B draws the most entries and attention at most every contest I have been too.

Get you facts straight and think about what you want to write your topic was concerning shutoffs not who did what not why you are displeased with them.

Scott

Brad LaPointe · « **Reply #2 on:** August 05, 2008, 06:59:19 PM »

OK guys I just got back tonight from France.On the subject of shutoffs everyone has an idea of the pro's and cons.I'm not going there. Just a note the Russians and Ukrainians did not have them for sale.When the muffler rule came out you could buy engines with the mufflers at the W/C's the summer before the rule came in.Make your own opinion on that.
As for particpation combat is probably stronger than speed and team race combined.F2B and combat both have active core groups and strong numbers .Very few people watch speed or stunt except when one's friend or countrymen are involved.Everyone watches the team race final.Combat had more spectators all the time than the other events combined.The last two days the stands were full ,the action very entertaining.
The politics of the F2 committee make most combat pilots see red.Every time our numbers grow "new" rules are invented to make it safer.Yeah right.The biggest problem for F2D in Europe seems to be too much of a good thing .Contests are becoming too big to run in two days.
As witnessed in France a new generation of pilots is emerging from the former Eastern bloc.Slava is now a judge,Boris the Russian combat coach.At least 5 juniors that could win any contest anywhere,anytime were seen.We(Canada) finished fourth .Our youngest pilot is over forty,the US and UK each had one pilot under forty .We need the kids more than rule changes.At least that's my take.

Brad LaPointe

Paul Smith · « **Reply #3 on:** August 05, 2008, 11:12:49 PM »

I got my numbers off the official FAI web site:

F2D = 92 entries
F2B = 89
F2A = 47
F2C = only 42.

I said: Combat was bigger than Stunt and bigger than Speed and Racing combined.

Assuming the accuracy of the FAI site, don't see where I was wrong.

Clancy Arnold · « **Reply #4 on:** August 06, 2008, 07:38:49 AM »

Paul
Could you clarify the "Fuel Shutoffs for F2d". What is required or allowed/not allowed?

Maybe then we could all see what you are talking about.

Thanks,
Clancy

dave siegler · « **Reply #5 on:** August 06, 2008, 02:25:52 PM »

I will do my best to stay out of the politics.

The motor must shut off in the event of a cutaway. It chased a lot of fliers away from AMA combat and slow. I think there are shutoffs that work OK for fsat now, but it took a long time. F2d will be more difficult, as the planes don't have as much line pull. Lots of people are working on it, and no one has a acceptable solutition yet.

Clayton Smith · « **Reply #6 on:** August 06, 2008, 03:52:53 PM »

Quote from: Clancy Arnold on August 06, 2008, 07:38:49 AM

Paul
Could you clarify the "Fuel Shutoffs for F2d". What is required or allowed/not allowed?

Maybe then we could all see what you are talking about.

Thanks,
Clancy

Clancy, take a look at the following site.

http://www.clcombat.info/shutoffs.html

Clancy Arnold · « **Reply #7 on:** August 06, 2008, 08:23:34 PM »

I think a reliable one could be designed electronically. If the bellcrank was non conductive then the lines and handle would complete a circuit to hold a solenoid open. Cut the lines and there would no longer be power to the solenoid and the spring would cut off the fuel supply. Does this sound feasible?
Clancy

Paul Smith · « **Reply #8 on:** August 06, 2008, 08:25:39 PM »

FAI and AMA Fast are two different events. A LOT different.

For starters, Fasts have .36 engines, vs .15's. Over twice the power and danger.

Furthermore, AMA rules END the match in the event of kills, crashes, collisions, line tangles, and flyaways. In FAI, the show goes on, pretty much, no matter what. Thus, in FAI you need to have a shutoff that can survive an "incident" and not put you out of action.

If it takes you 3 models to win an AMA Fast contest, it might take a dozen to win a similar-size F2D meet. That's a slew of shutoffs.

In AMA Fast combat, the flyers failed to do anything when Nelson engines put airspeed through the roof. They clung to .018" lines (which were mandated due to the SuperTigre C35). In a way the shutoff rule served 'em right.

F2d is another story. Since it's acceptance in 1976, there have been several speed-reducing actions: upgrade to .015" lines, 10% nitro, 4 mm venturis, and mufflers. Airspeed remains at about 100 MPH, far below it's peak of 120 before the rules changes. At this time there is no emerging problem that would logically justify shutoffs. It's a simple case of Monkey See / Monkey Do. AMA put in shutoffs, so FAI followed suit.

I don't expect this to kill the event, but it will be substantilly downsized, unless a miracle fix emerges from the Ukraine. Maybe some cheap, clean, domestic gas for our cars, too.

dave siegler · « **Reply #9 on:** August 07, 2008, 05:34:10 AM »

Quote from: Clancy Arnold on August 06, 2008, 08:23:34 PM

I think a reliable one could be designed electronically. If the bellcrank was non conductive then the lines and handle would complete a circuit to hold a solenoid open. Cut the lines and there would no longer be power to the solenoid and the spring would cut off the fuel supply. Does this sound feasible?
Clancy

The lines will have a lot of twists in it, so I don't know about that.

Clancy Arnold · « **Reply #10 on:** August 07, 2008, 06:29:13 AM »

Dave
I have only entered one combat contest back in 1965 so I have no current experience, but I need some information to base a design on.
1. Where are most line cuts? At or near the model, mid line, varies.
2. Weight requirement? Allowance.
3. Would coated lines be allowed. Note: that would have to be a rule change.

Clancy

Paul Smith · « **Reply #11 on:** August 07, 2008, 08:27:39 AM »

In FAI Combat, each flyer is allowed TWO complete sets of equipment to complete a 4-minute match. It is not uncommon for ALL FOUR airplanes and/or their lines, to be destroyed in a bout. One thing we don't need is more expenive lines.

This is supposted to be a FAIL SAFE device, so something that involve electonics, batteries, a servo, and some sort of logic to detect a flyaway would be INTRINSICALLY UNsafe.

Currently three systems exist.

Pendulum: A seperate pendulum with a spring is used to drive a pincher. Centrifugal force keeps it open as long as the model is flying in the circle.
Easy to install, but it adds weight & drag and works with a small amount of force, resulting in tricky adjustment.

Moving bellcrank: The bellcrank moves in & out like a carrier job with a spring pulling it out and centrifugal force pulling it in. A good system, but a lot of effort to retrofit on a existing model.

Line pull: A second set on leadout works a pincher. While the easiest to install, this system robs the flight controls of some input force.

Ground start/hold open/arming device Here's the kicker! All three systems need a way to temporarily keep the fuel line open until the model gets up to speed, then RELIABLY arm itself.

The technology for mechincal centrifugal shutoffs exists. The issue is scaling it down to FAI size and producing a MASSIVE number of units to equip about 8-to-12 models per contestant. As it is, flyers generally expect to lose about $100 worth of gear per match (assuming the $240 engines dodge the bullet). This will just drive the cost higher and probably trigger a reduction of participation. At least that was the fact in Fast & Slow.

We have no shortage of theories. What we don't have is an off-the-shelf device to buy. We have our fingers crossed that something will come out of The Ukraine in the next six months.

In the meantime, like FAST & SLOW, the guy who rig a shutoff will win the contest.

Paul Smith · « **Reply #12 on:** August 07, 2008, 08:48:30 AM »

Quote from: Clancy Arnold on August 07, 2008, 06:29:13 AM

Dave
I have only entered one combat contest back in 1965 so I have no current experience, but I need some information to base a design on.
1. Where are most line cuts? At or near the model, mid line, varies.
2. Weight requirement? Allowance.
3. Would coated lines be allowed. Note: that would have to be a rule change.

Clancy

To answer your question:

Flyaways are VERY rare in F2D, so there isn't much data on a failure mode that scarcely exists. Basically things happen so quick that nobody can honestly say WHY a plane got loose.

They happen a lot more in FAST, but these planes are twice as heavy and go 40 MPH faster with lines only one grade bigger. Again, things happen so fast and the model is so beat up, it's hard to say what went wrong, besides the admittedly marginal safety factor.

Clancy Arnold · « **Reply #13 on:** August 07, 2008, 12:09:07 PM »

Paul
Go back and read my suggestion again.

It would only require a solenoid, battery and a switch. The switch would arm the system when you are ready to start your engine and turn off the system when you land with the lines in tact. Any line cut would open the circuit and the solenoid would pinch off the fuel line.

I can't think of a simpler or more fail safe design. No mechanical adjustment or intermittent loss of control to worry about. Temporary loss of line tension would not activate the shut off. Only true line cuts would activate the shutoff.

Biggest advantage, American Made!!

Clancy

dave siegler · « **Reply #14 on:** August 07, 2008, 01:39:17 PM »

Look here. There is some good info here.

http://groups.yahoo.com/group/CL_Combat_Shutoffs/

Clancy Arnold · « **Reply #15 on:** August 07, 2008, 08:56:15 PM »

Dave
I hope they get a good design working. I really do not need an other project, but.

I thought some more about the design I suggested above and think I have an even better design for consideration.

Only the solenoid would be in the model. The battery and switch would be at or on the handle. When ready to start the engine the pilot would close the switch pulling in the solenoid and fuel would flow. At the end of the match the pilot only has to open the switch and the fuel stops flowing, engine shuts off. If the lines are cut the power to the solenoid is lost and the fuel stops flowing, engine shuts off.

End of match, open the switch, Land.

Simple,
Clancy

Paul Smith · « **Reply #16 on:** August 07, 2008, 10:56:34 PM »

Quote from: dave siegler on August 07, 2008, 01:39:17 PM

Look here. There is some good info here.

http://groups.yahoo.com/group/CL_Combat_Shutoffs/

That "H&R" shutoff looks promising. Does anybody have any pricing or source info?

Paul Smith · « **Reply #17 on:** August 07, 2008, 11:02:06 PM »

Quote from: Clancy Arnold on August 07, 2008, 08:56:15 PM

Dave
I hope they get a good design working. I really do not need an other project, but.

I thought some more about the design I suggested above and think I have an even better design for consideration.

Only the solenoid would be in the model. The battery and switch would be at or on the handle. When ready to start the engine the pilot would close the switch pulling in the solenoid and fuel would flow. At the end of the match the pilot only has to open the switch and the fuel stops flowing, engine shuts off. If the lines are cut the power to the solenoid is lost and the fuel stops flowing, engine shuts off.

End of match, open the switch, Land.

Simple,
Clancy

Sounds nice in theory...

Lets see,,, A fuel line pincher actuated by a spring,,,, A solenoid to overcome the spring,,,, Getting enough current through 104 feet of .015" steel line to power the solenoid. I'm not the EE, but it seems like a lot of Watts. Any estimate of the size power pack it would take to drive this device?

Question #2: Being that the lines are mandated at .015" stranded steel, how big would they grow with the insulation?

Clancy Arnold · « **Reply #18 on:** August 08, 2008, 12:06:04 PM »

Paul
The power of a solenoid is determined by Ampere Turns (the current times the number of turns in the winding). A solenoid with several hundred turns would only require a small current draw.

The present lines available measure .023 for .015 steel center and .028 for .018 steel center because of a .004 to .005 thickness nylon coating. BUT Some control line scale fliers are negotiating a price for lines with a .001 thickness coating which would only add .002 inch to the diameter of the lines.

Clancy

Howard Rush · « **Reply #19 on:** August 12, 2008, 01:13:09 AM »

You can have an electric shutoff with signaling through the lines without having insulated lines. Dean Pappas did this with stunt plane retracts.

Howard Rush · « **Reply #20 on:** August 30, 2008, 04:55:28 PM »

"As it is, flyers generally expect to lose about $100 worth of gear per match..."

That's why I started using shutoffs before they were required. Shutoffs save airplanes.

john e. holliday · « **Reply #21 on:** September 01, 2008, 08:36:05 AM »

Maybe the thicker lines would slow them down a bit. If every body was required to use the same system it might cause combat grow again. If we oldsters could get the youngsters off the computors and the so called organized sports we just might have a young team to send to the next worlds. DOC Holliday

Mike Greb · « **Reply #22 on:** September 02, 2008, 07:48:52 PM »

Quote from: ama21835 on August 05, 2008, 11:12:49 PM

I got my numbers off the official FAI web site:

F2D = 92 entries
F2B = 89
F2A = 47
F2C = only 42.

In F2C The team consists of a pilot and pitman, so there were 84 people competing in F2C in the 42 teams.

Howard Rush · « **Reply #23 on:** September 02, 2008, 11:59:15 PM »

"This is supposted to be a FAIL SAFE device, so something that involve electonics, batteries, a servo, and some sort of logic to detect a flyaway would be INTRINSICALLY UNsafe."

Do you realize, Mr. Smith, that commercial transport airplanes are flying-- perhaps over your very house-- under the control of something that involves electronics, batteries, servos, and some sort of logic?

phil c · « **Reply #24 on:** September 06, 2008, 07:12:26 PM »

After playing at the NATS this year, the string over the wing shutoff seems to be the best bet. For F2D it needs a latch to hold it open for starting, but for launch the pit crew would hold it open, with the pilot also pulling on the lines. It is in the air and armed with no problem.

A close second is a pincher type shutoff mounted on the motor mounts with an arm or short length of line looped around the rear leadout. The leadout line pulls the shutoff open when the lines are tight. Again, if it is mounted on the leading edge, the pitcrew can hold it open until launch, but it needs a latch for starting.

We also ran some sliding bellcrank shutoffs, ala Bob Mears. They worked well, although several times we had to launch with the shutoff tripped and the pilot pulling on the lines.

If you don't think shutoffs would be nice on F2D planes, ask Lester Haury. He caught a flyaway in the back at the Worlds(see Evil Emo's report). Didn't look lifethreatening, but I'll bet it sure hurt! We're starting to put shutoffs on speed limit planes for the same reason. No matter how careful you fly, midairs happen by accident about 1 match in 8-10. Cutaways happen in maybe 1 in 10 to 1in 20 midair situations(near misses). Many of them crash close by and quickly, but that still leaves something like 1 threatening flyaway in 4-500 matches. We've only had a very few flyaways locally, but one of the above systems will cut that down to nearly zero and they aren't a huge hassle.