Fuel versis batt at weigh in

[bob whitney]

 while looking for something on Proxy flying in general rules ,i came across this on weighing planes for pull test. it says the plane will be weighed with a full tank of fuel or with the battery in it.  the speed flyers are the only ones i know of that add the fuel to the weight of the plane , if we have to weigh our stunt and scale electric planes with the battery in it then something needs to be added to the fuel jobs to even things out.

[pat king]

The total aircraft weight is used to determine the pull test required. To have the proper safety factor the pull test weight is determined by the total flying weight of the airplane. Since the pull test is now based on a multiple of the airplane weight there is no advantage or disadvantage for the type of propulsion system when it comes to the pull test. The same airplane with electric power will normally weigh more than that airplane with fuel power. Therefore it is reasonable and proper for the heavier airplane to have a higher pull test. There is no advantage to the fuel powered airplane in the pull test. A 30 oz. Ringmaster has a lower pull test than a 48 oz. Ringmaster whether they are both electric or IC.
There is no handicap given to fuel powered airplanes for governors or timers on electric airplanes.

Pat

[bob whitney]

 the advantage is that right now the glo ship is being weighed without fuel and the electric has to have the battery

[Fred Cronenwett]

I thnk the rule proposal for CL scale is written so that glow powered models are weighed without fuel which is not a big deal because they add so little fuel compared to the overall weight of the model.

The electric powered models will be required to weigh the model with the batteries because the batteries can really add up. I put almost 3 lbs of lipo batteries on the B-29 that I fly in CL scale when I get it ready for flight. So the overall weight of the model with batteries makes a difference and that is what gets flown so that affects pull test

Make sure you read the CL scale proposed rules since the current set of rules will be probably be replaced with the proposed rules for CL scale

As for what is happening in CL Stunt not sure how they do that with Aerobatics

There is also major changes with the the line diameters in CL scale, hopefully folks are paying attention, the line diameter on the larger models is getting bigger (anything above 8 lbs especially)

Fred

[Steve Helmick]

Can't help but wonder why this idea didn't come up, oh, 3-4 years ago? Oh, wait...it DID!  Steve

[Paul Walker]

The total aircraft weight is used to determine the pull test required. To have the proper safety factor the pull test weight is determined by the total flying weight of the airplane. Since the pull test is now based on a multiple of the airplane weight there is no advantage or disadvantage for the type of propulsion system when it comes to the pull test. The same airplane with electric power will normally weigh more than that airplane with fuel power. Therefore it is reasonable and proper for the heavier airplane to have a higher pull test. There is no advantage to the fuel powered airplane in the pull test. A 30 oz. Ringmaster has a lower pull test than a 48 oz. Ringmaster whether they are both electric or IC.
There is no handicap given to fuel powered airplanes for governors or timers on electric airplanes.

Pat

Your logic is flawed!

Electrics take off with the full safety factor and maintain that for the entire flight.
Gas planes take off with a reduced safety factor because they are weighed without the fuel. Thus their safety factor is less at the beginning (because they weigh more then) and at landing they finally match the electrics.
Therefore, there is an advantage to the gas powered planes. The point of where they have to switch line sizes for the same safety factor is lower, thus some are able to fly on thinner lines that the "equivalent" electric.

Might me time to consider weighing with a full fuel load!

[RC Storick]

I think the pull test is already over kill. I have seen more bellcranks pull out then lines break. (Pat) Paul is correct but its still over kill for both.

[bob whitney]

with todays Bellcranks ,there is no excuse for a bellcrank coming out of a plane . what hurts is when one line breaks and the other line tries to pull the bellcrank around further then it was ment to be

[Fred Cronenwett]

There is an extensive white paper on the line tension and the safety factor for each line dia size for CL scale. Bottom line the CL scale guys are worried about the line diameters and the safety factor to make sure that we don't have any lines break.

CL scale will be requiring the electric powered models to be weighed with the batteries for pull test if the rules are approved

You can take this data and apply the weight of the aerobatic models...maybe this makes the situation more complicated!

Look at this cross proposal for the CL scale side of the house, this is the technical rationale for increasing the line diameter for the CL scale models to .027 for some of the heavier models.

https://www.modelaircraft.org/files/CLSC15-4CP2.pdf

Fred

[James Mills]

Two items. At almost every contest, the fuel and electric planes tend to be weighed while on the spinner. So, if one forgets to cap the uniflow vent, fuel will spill all over the scale, etc. Also how much really does the volume five ounces of liquid weigh?? Not much and not enough to really matter. This is a mountain out of a mole hill, a tempest in a tea cup. Must be too hot to fly some where.

Typically an ounce of fuel is equal to adding one ounce to the weight of the plane, so 5 ounces of fuel would be another 5 ounces of weight.  At the Nat's this year my plane weighed 65 oz even so I use .018's but another if another flyer who had an IC plane that weighed 64 dry they could use the .015's, and most 60's are going to use at least 6 oz of fuel so at takeoff, way north of the safety cut off as Paul mentioned and an advantage.

James

[Chris Wilson]

the advantage is that right now the glo ship is being weighed without fuel and the electric has to have the battery

That is at odds with your original post(?)

[pat king]

Your logic is flawed!

Electrics take off with the full safety factor and maintain that for the entire flight.
Gas planes take off with a reduced safety factor because they are weighed without the fuel. Thus their safety factor is less at the beginning (because they weigh more then) and at landing they finally match the electrics.
Therefore, there is an advantage to the gas powered planes. The point of where they have to switch line sizes for the same safety factor is lower, thus some are able to fly on thinner lines that the "equivalent" electric.

Might me time to consider weighing with a full fuel load!

The original post stated that fuel powered airplanes are to be weighted with a full tank. To maintain the desired safety factor all airplanes should be weighed with everything they will be carrying when they launch. If fuel powered airplanes are weighed without fuel the pull test is not as much as it should be. If this is the case then the fuel powered airplanes are not getting a sufficient pull test to satisfy the safety factor desired..

Pat

[Paul Smith]

If we are really interested in true safety, not just a political arguement, all models should be weighted at their maximum flying weight.  Which is to say with a fuel full load and/or a fully charged battery.

I suggest that the contestant be given the choice of actually filling the tank or accepting a 10% fuel weight allowance.  Thus a 40 oince model would assume 4 ounces of fuel weight; a 60 ounce moedel would accept a 6 ounce fuel weight.

The G factors in stunt are so small that the pull test is a mere token gesture.  If stunt flyers are sthis skert of the pull test they should accept a substantial increase in line diameter in lieu of the pull test.

[James Mills]

 Which is to say with a fuel full load and/or a fully charged battery.

Not trying to be smartalec, but the battery weighs the same charged or in storage mode.

James

[Brett Buck]

If we are really interested in true safety, not just a political arguement, all models should be weighted at their maximum flying weight.  Which is to say with a fuel full load and/or a fully charged battery.

I suggest that the contestant be given the choice of actually filling the tank or accepting a 10% fuel weight allowance.  Thus a 40 oince model would assume 4 ounces of fuel weight; a 60 ounce moedel would accept a 6 ounce fuel weight.

    This is unnecessary. The factor of ~4 margin built into the pull tests cover the fuel weight adequately well, and for my money they cover the weight of the battery adequately. So if we do anything, we can weigh it without the battery. It doesn't matter either way.

      Brett

   

[Paul Smith]

From what I've seen, batteries weigh a lot more than liquid fuel.  So fuel or batteries in not a wash.  I would rather put 4 ounces of fuel in my thank than let electrics get by with a 10-12 ounce advantage.  That could equate to a full line size advantage.

[Brett Buck]

From what I've seen, batteries weigh a lot more than liquid fuel.  So fuel or batteries in not a wash.  I would rather put 4 ounces of fuel in my thank than let electrics get by with a 10-12 ounce advantage.  That could equate to a full line size advantage.

Oy vey and oy gevalt! Its a wash in terms of safety and pull test, far under the limits of the margin.

It's also more-or-less irrelevant from a competitive standpoint in the size airplanes flown in stunt. I have flown on oversize lines for years, it actually works better on my airplane. So it just doesn't matter.

    Brett