R3d Ryd3r

My Feedback: (2)

Hey guys, I am wondering about the weight limit for AMA and NSRCA Pattern planes? I know that in the sportsman class, no one at a regional contest is going to weigh your plane and kick you out for being over the 11lb limit. But at the higher classes, and at the NATS, your plane must be below the limit to be legal. If someone from the AMA or the NSRCA would care to explain the reasoning behind the 11lb weight limit, I would like to hear the answer. It seems to me that with modern electric components, you have about 6lbs of airframe including wheels prop/spinner, and about 5lbs for motor/ESC/Servos/Battery/Etc..... If your plane is heavy it will not perform the same as a lighter plane, but why make the bar so low and restrictive? is it just to drive up the cost? Why on earth would you drive the cost up for everyone? Does not make any sense to me.....

big_G

I agree. I see pilots spending hundreds of not thousands of dollars with carbon fiber parts and expensive in-runner gear drives just to make weight. If the limit was 5.5 kg...about 12 lbs., the cost to fly would come way down.

KC8QPU

I am positive that it is not to drive the cost up!!! I just started flying pattern this year. I have flown two D2 contests. I currently fly an Eflite Splendor. This is by far the smallest plane sitting on the line by almost 20"s. It flies extremely well and costs a fraction of the price. Obviously its well under weight. So you really don't need to spend Thousands of dollars to have fun and be competitive.

However as you have already mentioned a lighter plane performs much better. But in some cases it does not fly nearly as well as a heavy plane. Seeing as your from Hawaii I am sure you know all about the wind factor.

I think as long as you do not plan on going to Nats or at worlds I would say most regional events do not weigh planes.

Just go out have fun, meet people and become the best pilot you can.

Dave Harmon

Not really......

I have a BJ Craft Essence that weighs 4860g ready to fly and is a fully competitive airplane in FAI as well as AMA schedules.
I also have a BJ Craft Nuance that weighs less than that.
These two airplanes do not have a scrap of carbon fiber or in-runner drives.
I did splurge a bit though and use a Mejzlik 3 blade prop.

I am not the only one....there are many guys that have these airplanes and I would guess that they are all well under the 5kg limit.
You would be amazed at how well they fly compared to almost anything else....properly setup though....setup is everything.

Dave

big_G

Dave...I was partially thinking on the lines of the initial price of the plane. Most higher end aircraft are designed to be light....Both of my less expensive planes, a Vanquish and Caelus will not make weight (5K), even with the carbon prop and spinner. Now I fly Intermediate, so I have an increased weight limit if I go to the Nats. Many of the guys flying Masters and FAI are using 5,500-5,800 ma. batteries, so they have a tougher time than I do making weight.

Dave Harmon

Hi B_G.....I don't mean to keep disagreeing with you but I have never heard of anyone using a 5500 or 5800mah battery for Masters or FAI.
Personally I have been using F3A-Unlimited Power Unlimited batteries for over 4 years now.
I have the 5100mah 35C and they are physically a lot larger and heavier than the 5400mah 25C packs which I will be using this year.
These have plenty of power to fly all the Patterns.
IMO...we don't need the larger continuous discharge ratings...ie 35C, 75C etc....as the helicopter guys do.
We need more capacity but at a lower more constant current draw...so we can get away with a lower C rating and save weight.

Dave

R3d Ryd3r

My Feedback: (2)

I understand people spending big bucks on high performance lower weight components, they want the plane to perform. What I don't understand is how a heavy plane gives the pattern flyer an advantage? Yes wind is a factor, but a heavy plane is not going to be a significant advantage in light winds, or even in a moderate wind. Just wondering the reason for the restriction.

R3d Ryd3r

My Feedback: (2)

So the Essence is a 2M Plane made by BJ-Craft. At $2200.00 its not exactly cheap, and the cost to outfit the plane with new components from F3A-Unlimited WITHOUT the Transmitter and SHIPPING is around $4000.00 I know there are more expensive birds out there, and that this is a great airplane, but I'm just wondering if making the 5000g weight restriction is the reason the sum of the parts are so costly.

Smooth Pilot

I have a 2 meter Vanquish (@$750.00 not counting shipping), an inexpesive motor (Tacon 160 @$56.00 not counting shipping) that is powewrful but heavy, and the servoes are various Hitecs high voltage high torque and an Airtronics radio. The whole plane ready to fly with batteries (2 Zippy Compacts, 25C, 5000mah @$45.00 each) is slightly under 5KG. It can be done. I am flying Intermediate, but I have seen several Vanquish planes in Advanced, and at one contest saw someone fly Masters and placed.

Sheldon

R3d Ryd3r

My Feedback: (2)

Sheldon, Absolutely the Vanquish is the best solution for keeping the cost down, hopefully the AJ-Aircraft 2M (yet to be named) plane will be competitive with that price point. But I am not really complaining about the cost, but really trying to understand the logic behind the restriction. Is a 12lbs aircraft really going to give a pilot at the top levels of our sport an advantage over one that weighs 11lbs? I know that a lighter airplane is better for 3d and extreme stall flight maneuvers, but for NSRCA pattern there has to be a reason for the limit, other than just to "make weight"

rgburrill

If you set the limit to 5.5kg someone will whine about it not being 6kg.

big_G

Most everyone could meet 5.5 kg using standard quality/priced components....
I think the 5kg limit came about a long time age, before electric. Glow engines are much lighter than equivalent electric systems, especially when you factor in the weight limit for glow is without fuel.

Dave Harmon

I think there is a general thought that the heavier and larger the airplanes are will drive up the cost because the thought is that they will require larger engines/motors and the associated larger amounts of fuel....either liquid or solid. Also...there is a size restriction....which goes hand in hand with the weight....ie...can't make E-planes much lighter than they are today unless the size is reduced or a new material and new techniques come along.



I can't imagine where you are getting those cost numbers from.
(edit....because of the way you worded your above comment....I assumed that you did not include the cost of the Essence...."cost to outfit the plane".

Motor $560
Esc $150
4 servos about $110 each
Replacement hardware about $50>$75 depending on choice
Spinner Falcon $70
Prop...the most expensive 3 blade is about $150
Motor mount about $50
4 sets of batteries about $800 for the good stuff
Misc stuff glue etc...$50

Total $2345 not counting the radio.

I don't get you thought process.

Agreed....totally!

Glow airplanes....especially 4 stroke powered must be built to withstand the pounding of the engine...so that makes the empty airframe weigh a lot more.
Of course....E-power does not have the vibration problem so everything can be built much, much lighter....this includes the hardware, linkages and all other stuff.
I have not mentioned the additional weight of glassed surfaces and painted wings and tail, adjusters and more glue and structure.
Electric planes don't need most of that stuff.....except paint...of course paint is just preference by the builder but most painters don't know when to quit...including me.

One other thing that I was told a long time ago....'no one flies inexpensively.....you can minimize the cost but flying is always expensive.'
And.....you get what you pay for.

Dave

SAB

The 11lb limit comes from the FAI limit for pattern of 2x2M max size & 5Kg max weight

Quite a few years ago there was also a 10cc (60) engine limit. There were calls at the time to have an unrestricted engine capacity limit to lower the cost of pattern as the 10cc engines were becoming quite specialised for pattern & therefore
expensive. If the engine size was unrestricted then cheaper but higher capacity engines could be used. Well engine capacity did become unrestricted, so did that lower the cost ? - NO it had the opposite effect and we got larger capacity
Specialised F3A engines that were even more expensive !!

IMO if the weight limit were increased then a similar effect would occur and cost would increase - I can imagine, for example, if a weight limit of 6Kg (13.2 lb) was allowed then we could get super “bloated” BiPlanes with full 2M wingspans and exotic/super expensive power systems to drag them around the sky....

Steve

Anthony-RCU

My Feedback: (2)

Thank you Dave and Steve you saved me a lot of typing! In any competitive event the participants will push for any perceived advantage to the limit of the rules. We have seen displacement grow from .60 to 1.20, 1,40, 1.60 1.70 and now 1.85 with CDI and several versions of more complex soft mounts all at higher cost and complexity. And no one will compete with just one engine. We have also seen simple brush-less motors grow to complex gear or belt drives and even counter rotating systems.
It is counter intuitive but fewer limits gives more room to increase cost and complexity. Rules are part of any competition and one must always be keenly aware of the unintended consequences of changes.

R3d Ryd3r

My Feedback: (2)

SAB, I see now that historically pattern guys that wanted more power in a plane that had a 2M wingspan, while flying glow fuel meant heaver and more complex engines (the YS 185-CDI Four-Stroke comes to mind) to produce that needed torque and thrust, and keeping the weight at 5000g kept the horsepower wars from escalation into more and more complex IC engines.

But now I think we have the opposite problem, with Electric power the inverse is true, the less expensive power plants (or Motors) that are built to produce around 2500 Watts tend to be heavier than the expensive F3A type motors that are on the market. Batteries have the same inverse relationship, the cheaper the battery, the more it tends to weigh with the same capacity. (debatable I guess but it seems that way to me) and if you want to scratch build a 2M size plane out of Balsa and Ply, you will have a tough time keeping it under the weight of 5000g with same running gear that is recommend for top performing composite ships.

If that is the answer, that back in the Glow Fuel Days the displacement of the engines was a concern, and keeping the weight below 5000g was the goal to discourage bigger and bigger power plants, I can see that. I think the rule is archaic and should be amended to reduce the cost and simplify the construction of a pattern planes that are more and more using Electric power.

R3d

SAB

R3d,

Actually when engine capacity was 10cc there were no 2M or 11lb planes, they were typically around 65" wingspan and 7-8lb.
The unrestricted engine capacity rules (to allow use of cheaper engines !!) drove the size and weight increase of planes to the 2M & 11 lb limit !!
Increasing the 5kg limit would IMO escalate the cost once again, as I said previously.

Now,for all but the highest class you don’t need a full 2M plane. The Sebart MythoS 125 is a great example (there are others) - almost 2M size at 1.9M and 1/3 the cost of the MythoS Pro, flies great on 8S with either a Hacker or Motrofly
$200 motor. I’ve seen this model also do very well on 10S with low cost motors.

Steve

MTK

I continue to play with gas engines for pattern and have to inform the uninitiated that this power source is perfectly viable for this sport. Gas engines and pipes are comparatively inexpensive to own, operate and maintain. The OS GT 33 on pipe and the DA35 on pipe put out just as much useful power as the YS 185. Just started flying my Griffin converted to gas (OS GT33, ESComposites 40G pipe) which weighs about 155 ounces. Performance to bern.

Should the powers that be bump up the weight limit to 5.5 or even 6 kilos, either the valley view or DLE 40 cc twin on pipes will easily haul the mail. And these engines are so light there is little reason to be heavier than 5.5 kilos. On pipe, output is close to 5 hp and will turn 22x8 or 9". Neither of these power plants are expensive and are simple to operate and maintain. Of course, there are those that just love to spend their money....okay with me.

MTK

Dave see my previous post about the Griffin conversion to gasoline. Much lighter than the electric versions flying at present and as you may know the Griffin was originally designed as electric only. I am using an 8 oz tank which flies the crate for about 15 minutes. I don't think I fly expensive.

Dave Harmon

Hi Matt......I always read your stuff so I am familiar what your preferences are.....sounds like a good use for those Griffins.

Whatever happed to the Syssa deal?
From some of your posts and other info I read indicated that it was a good handling engine purposefully designed for model airplanes but needed more development due to being a bit low on power.

I had been wishing for a decent gasser to be available but then the E-power came on and that was that.

Dave

MTK

Dave,

The Syssa 180 is a decent racing engine. Loves to rev. I tried detuning it to turn reasonable loads at decent rpm but it just wasn't optimal.

My current choice for the past roughly 5 years is the GT33. Turns the same props as the 185 at the same or better rpm. Best of all is the mid range torque which rivals the YS. And on the light Griffin, I use 1/3 throttle to 1/2 for verticals. 8 ozs lasts 15 minutes, no fib.

There are a few guys in France flying the RCGF32 and report good results with that one. I've not tried it so can't say definitively. It's only 250$ or so. And Ron Mc is running an EME35. There are several inexpensive choices. These are simple sport engines no different than the OS160FX, except they are on steroids and perfect for pattern

Dave Harmon

Sounds good Matt.
Perhaps some of the guys entering Pattern will see this and realize that your above description is definitely competitive.
The best thing is that instead of $30 or more for a gallon of hard to get fuel.....all they gotta do is head to the local and buy a gallon of gasoline!
Wait till them guys get a load of the sticker shock on a 4 sets of decent batteries....HAW...but they will last hundreds of flights.

Dave

FinnSpeed

But how does the gas engine do in sound pressure test? That is also controlled in major events and in my experience the gas engines are much louder than the YS or electric. I may be wrong about this...

By the way, build up surfaces tend to be lighter than full composite surfaces. The fuselage may be the opposite case - full composite ones can be lighter than balsa/ply structures.

I sort of agree that the weight limit could be lifted a bit to make it easier to get an ARF 2m pattern kit under the limit. For example, my Spark Evo 2 is some 200 g overweight at the moment which is mainly caused by the motor which weighs about 670 g with prop mount and mounting hardware. This motor works just fine and delivers more than enough thrust and costs only about $150. It will be replaced with a Hacker C54 which is 170 g lighter (and considerably more $$$) soon... However, making the 5 kg (or 5050 g) limit is not the only reason to change: A lighter plane will fly better and the motor is higher quality and will last for hundreds of flights. There may be other bonuses as well like easier throttle management and better braking etc. It will also cool directly from the built in air scoop of the Spark without carving the spinner cone full of holes.

papaone

Hello

Matt I totaly agree with you.
the most economical pattern is to make yourself as labor is not counted, with gas engine.
Sometimes weight is upper 5 kg. But in France serie Nat A and B (equal advanced and master) limit weight is 5,5 kg.

Finn
"A lighter plane fly better" !
I'm not sure, tank full or empty ; fly is the same with about 500 g difference.
Claude

On these patterns engine is RCGF32 very cheap !

MTK

my setups are rubber isolation mounted and piped and use APC props or props of my own design, all noise suppressing. My GT33 powered planes have been noise tested (about 92 dB for the noisiest, about 90 for the quietest all measured normal to the fuse at 10 feet over grass). These don't sound like any gas powered setup you have ever heard and don't fly like it either.

Any electric only plane can be converted to gas or glow. I don't buy that these models are built too lightly. On the contrary, we have been duped by the mfrs that IC planes must be beefier. Well, the Griffin was an eplane which I converted. I put it on a diet during the conversion, removing unnecessary weight such as landing gear blocks and plywood firewalls for lighter and stronger alternatives I designed. The model with a full tank of gas is about 10# 2 ounces (4600 grams). That's light enough.

And if I wanted even less weight, I could build a new set of wings and stabs from balsa as I am currently doing for my Delta. Weight savings, even all paint, is considerable at about 100 grams per panel for wings and 25 grams per panel for stabs. But since the Griffin is just an ARF and is plenty light, it just isn't worth the effort.

one thing certain, flying a really light plane will spoil you. Even 8 ounces difference is something you feel in the air. I also don't buy that a heavier model flies better in the wind.....my Temptress and now the Griffin, both at 10# or less, simply damp faster in wind. Neither plane is small....both are two meter types with well over 1000 sq inches of wing.

Oh yeah, almost forgot....Temptress is 14 years old with at least 2500 flights; she is in deserved retirement. LOL!