Want to Talk AMA CL Endurance?

[Motorman]

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[Tim Wescott]

I'm kinda interested -- I even have a drawing of a Deezil that's been marked up to bring the displacement down to 0.09, and with teeny transfer, intake and exhaust holes, and the most gawdaful undersized bearings (for a "real" 09) that you can imagine.

But no metal has been cut on the project to date -- I'm concentrating on CLPA.

I think if you want Endurance to be a real event, you need to have Endurance meets, with trophies and possibly regional and yearly "best records".  Just "shoot for this unattainable goal" is going to make it hard for the competition minded to bestir themselves, I think.

[Balsa Butcher]

You may check with the Knights of the Round Circle club. I think member Kenn Smith (who passed too early) led an attempt to set a new endurance record 15 or so years ago. Plane of choice was a model of Lindberg's Ryan NYP.

[Jim Thomerson]

I've been interested, and have had some correspondence with someone on the forums some years back.  CL endurance is an AMA event.  The person in question got the specifications changed from a 4 oz tank to a 1 oz tank, because the flights were getting up to several hours (as I recall)  The engine was a Medallion 09 glow, with a 1/64 venturi opening run on diesel fuel, again,as I recall.  When records are made, there is an AMA form which is submitted with all the details.  I made several phone calls to AMA Headquarters, and sent two letters requesting a copy of the record application for Control Line Endurance.  For my troubles, I received a blank record application form, and gave up in disgust. 

So the event is a closely held secret, and if we are interested, we can start from ground 0 and muddle along as best we can. 

[Tim Wescott]

It's something like 1 oz (specifically no more than 30cc for the entire fuel system), displacement between .0900 and .3661 cubic inches, minimum line length of 52.5 feet, minimum diameter is .018" for two-line multistranded, .014 for two-line solid, and .016 for single-line.

Given the required size of the lines, the contest sounds more like "how long can you keep those wires aloft" than an airplane endurance contest -- but hey, roolz is roolz.  I think I'd learn to fly single-line if I were serious about the event.

[FLOYD CARTER]

With max fuel and engine displacement specified, where is the challenge?  This limits innovation to some sort of modified diesel and not much else.

F.C.

[Tim Wescott]

With max fuel and engine displacement specified, where is the challenge?  This limits innovation to some sort of modified diesel and not much else.

I dunno -- once you've innovated an engine that runs for 30 minutes on an ounce of fuel, you need an airframe that's going to keep those lines in the air on the available power.  While the "engine runs reliably for a long time" part is a challenge in and of itself, keeping at least minimal line tension on those heavy long lines, possibly in at least some breeze, can't be an entirely trivial thing.

(This is actually why I think there would be some fun in having endurance as a regular event -- with multiple people flying, you wouldn't be able to pick your wind.  So there would be some definite tradeoffs to be made between what engine performance you set that day vs. the wind.)

Someone on this group reported setting the NW record on the new fuel tank size at around 20 minutes with a stock Chinese Deezil bought off of Ebay.  The record stands at something like 22 or 25 minutes -- so I think there's room for improvement.  I know there's a guy whose got the national record in his sights, but I don't know if he's actually flown it yet.

As someone who gets bored easily and believes in drinking tea, I'd rather have an event limited by the available fuel than by my available bladder space.

[Balsa Butcher]

Also, back in the day, WAM (Nor Cal C/L sanctioning group) used to offer Endurance as a regular event. It died out in the 80s or early 90s. Don't remember the rules but I'm sure they differed from the AMA version.

[John Tate]

Willis Swindell and I thought about doing the Endurance event many years ago. We started out with a Super Tigre 15. I made a Delrin venturi adapter threaded for a TD .020 venturi/needle valve assy (just to see if that small of venturi would work. We then tried a PAW 09 but the connecting rod was too soft.

We talked to several guys that had the capability of making us a low timed .09 piston/liner that would fit one of many .15 cases that we had at the time but could not get anyone to do it. We might have over thought the process of trying to get the most mileage out of a diesel engine. We even reduced the crankshaft timing by filling in the port on the crank by inserting a piece of brass and silver brazing it in. We finally gave up when we could not find a .09 diesel that would hold up to all the testing we needed to do.

John Tate
Norfolk Aeromodelers

[Tim Wescott]

We might have over thought the process of trying to get the most mileage out of a diesel engine.

Isn't it strange how "best ever (if I finish it)" never seems to hold a candle to "actually done and sorta working"?

[Brett Buck]

Also, back in the day, WAM (Nor Cal C/L sanctioning group) used to offer Endurance as a regular event. It died out in the 80s or early 90s.

   Not just an event, it had engines classes and skill levels. Endurance was one event, and Economy was another. As far as I can tell, that date is about right. The last full-up WAM contest I ever attended was Fun(d) Day in 1989 or 90, and that may have been the last time it was offered.

    Brett

[john e. holliday]

Back in the day  of the Sky Devils of KCMo.  we ran endurance event as number of laps air born.   Any plane with .35 size engine and only one ounce of 10% SIG fuel.   The lines were .015 cable, 60 feet center of plane to center of handle.  Was over a 100 laps of trying to maintain level flight with the smallest circle I  could do with hand on the chest.   This was with a glow engine.

[Paul Smith]

I pushed through the rules change from "all the fuel you can carry in a four-pound model" to "4 ounces of fuel". That rule was effective in 1980.

The old "4 pound" rule really made it an all day marathon.  In retrospect, guys were able to fly almost as long unde the ounce rule as the pound rule.   Hence, somebody cut it ONE ounce.  I think the .018" x 52' lines is an OK rule.  It adds drag, wastes energy, and gets the flight over a little sooner.  Sure, you could fly longer of thinner lines, but an event needs some limitations.

The problem is, the event always boils to winning by running an engine over lean with some life-threatening funny fuel.

[50+AirYears]

I seem to recall sometime around 1958 Flying Models having coverage of a real endurance attempt.  I think something like a Ringmaster with a McCoy .29 or .35, and a long length of fuel tubing running from a pump with bottle on the pilots belt running up to the filler vent on the plane.  I have this idea the attempt ended after several gallons and at least 19 hours because of a blown glow plug.  Anybody remeber this better than I do?

[john e. holliday]

I beleive the club of the attempt did go over 26 hours before calling it quits.  The engine was still running when they did not refuel the on board tank.  Also it was a plug for the glo plug as it was still good.   Maybe someone will dig back thru there past issues of the mid 50's.