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HelicopterGasser Model RC HelicoptersOther › Is there a stronger engine for the radical?
12-30-2009 02:20 PM  7 years agoPost 141
AceBird

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Utica, NY USA

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Doesn't make a difference who makes it, as long someone makes it, The engines are here, What we need the heli, Wally
I would be more than happy to design/make the first prototype but someone else has to market it. The new Condor is the direction the design should go for a robust engine but Century has the price up so I think it's numbers will be low.

Face it Wally, people are different. You will never have one heli that will be attractive to everyone. That is why it takes a large enough organization to supply a fleet of different sizes and power plants.
why it's such an issue to build a frame that goes together idiot proof and isn't made of chewing gum beggers my imagination in contemporary times..
It's a lot harder than you think. When the forces go up the design is extremely important otherwise the weight goes up and defeats the increase in HP gained by the modded engine. If you just take an existing frame like a Trex for instance and shoe horn in the stronger engine you will be chasing screws or loose parts (hopefully not flying independently).

Ace
What could be more fun?

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12-30-2009 05:03 PM  7 years agoPost 142
James Kovach

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canton, oh - US

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Does anyone 3D a nitro at 1800?
Well, the pros do not, but I know quite a few people that do. Infact, I know that Matt Botos practices his 3D routines at 1600-1700 rpm. So it is not that it is not possible.

Another thing is, Gassers and Nitros need to be flown differently. You fly a Nitro "on the RPM" and a Gasser "on the Torque". What I mean by that is, a Nitro engine needs the high RPM to keep the head speed up. It will not really maintain that head speed, but it is high enough that it can drop and you will not really notice it. Now with a Gasser there is enough torque there it does not need the RPM up to maintain the head speed. The benefit of that is, you will see very little drops in your head speed and have a more consistent flight.

I still have a hard time getting this to sink in my head. Everytime I fly my Radikal at 1800rpm, it feel like it has the same "pop" as my Knight does at 2000rpm. After looking at some datalogs, I finally figure out why. When I jam the collective on my Radikal to do a full collective climb out, the head speed just does not drop much if any at all. But on the Knight, it will drop down to that 1850 or so range.

*disclaimer: These are my opinions. Agree or disagree, Your Call :)
Let'r Rip Tator Chip

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12-30-2009 05:16 PM  7 years agoPost 143
rccarguy

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Boston MA

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When I jam the collective on my Radikal to do a full collective climb out, the head speed just does not drop much if any at all.
Just out of curiosity, what gearing and pitch settings are you using?

XCell Spectra G
Radikal G20
Some obsolete nitro helis too...

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12-30-2009 05:33 PM  7 years agoPost 144
Billme

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MS

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Also, just a reminder... If you have your throttle setup wrong, you can tweak till cows come home, and it will never run right ...You will be constantly moving needles...

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12-30-2009 05:35 PM  7 years agoPost 145
James Kovach

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canton, oh - US

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1800 rpm with 10 pitch and 6.4 gears. There was a dramatic improvement from the 6.0 gears and I suspect that when I goto the 6.9 gears, it will not budge at all when I hit it.

I also re-tuned my engine at that time for the 1800 rpm. I have found that you cannot tune your engine for 1900rpm and expect to get the best performance out of it when you change to say 1800 rpm. You need to re-tune to that rpm. Same as you do with a Nitro.

*disclaimer: These are my opinions. Agree or disagree, Your Call :)
Let'r Rip Tator Chip

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12-30-2009 05:40 PM  7 years agoPost 146
pgkevet

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Wales

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If you just take an existing frame like a Trex for instance and shoe horn in the stronger engine you will be chasing screws or loose parts (hopefully not flying independently).
That (of course) is not what i said. I fully appreciate that a different powerplant may require modification to existing design. However i doubt that the current crop of trex gasser conversions have any more screw chasing than the current crop of 'purpose builds'

But a basic head system is just that. A basic radio bay is just that. Some thought to wiring runs is long overdue. A modular tail end to bolt in the frame, a boom and tail box that you can get at can be plaigeraised from all sorts of places. A landing skid system that can cope with a bounce but still give rather than sacrificing itself and throwing heli over doesn't seem too much to ask. That just leaves an engine mounting and main gear system and main shaft bearing system that required gasser approaches - with enough thought to actually get at stuff to service it. And stick the fuel tank where you can see it... if you can't then have a mechanical guage/float/whatever that you can see.

Accurate machining shouldn't be an issue, indexing parts shouldn't be an issue. Yeah, there will always be a need to modify in the light of experience but knocking out kits 'cheap' with overpriced 'upgrades' is not my way.. design it and make it right..change it if you have to.. but one basic set of parts for one powerplant class. You will never make it all things for all people.

pgk

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12-30-2009 11:41 PM  7 years agoPost 147
C.A.P.

rrApprentice

custer park IL.

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[quote]Accurate machining shouldn't be an issue, indexing parts shouldn't be an issue. Yeah, there will always be a need to modify in the light of experience but knocking out kits 'cheap' with overpriced 'upgrades' is not my way.. design it and make it right..change it if you have to.. but one basic set of parts for one power plant class. You will never make it all things for all people[*]

[I disagree IT,s important for accurate mac hing, for a heli to stay together, Just as important to have an engine that is put together just for heli's, Cost, well with the way the world is, That will come down too, or we will lose heli companies, that a fact, And cheap helis companies do not make the money off the kit so much, it's us crashing and buying replacement parts & upgrades, Other wise we would be making our own parts, And real good heli companies the replacement part are higher then the cheaper heli companys upgrades, It's up to the customer to show their disappointment in a product to get changes, Like the G no good gear ratio's, you guys should be screaming that them, So do what your old lady does, when not happy BITCH!! The future of heli's will not be 12,600 to 13,000rpm it will be a lot lower, and gr ratio's will be lower, because high torque will be flying your heli's not rpm. Wally

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12-31-2009 07:48 AM  7 years agoPost 148
pgkevet

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Wales

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[I disagree IT,s important for accurate mac hing, for a heli to stay together, Just as important to have an engine that is put together just for heli's, Cost, well with the way the world is, That will come down too, or we will lose heli companies, that a fact, And cheap helis companies do not make the money off the kit so much, it's us crashing and buying replacement parts & upgrades, Other wise we would be making our own parts, And real good heli companies the replacement part are higher then the cheaper heli companys upgrades, It's up to the customer to show their disappointment in a product to get changes, Like the G no good gear ratio's, you guys should be screaming that them, So do what your old lady does, when not happy BITCH!! The future of heli's will not be 12,600 to 13,000rpm it will be a lot lower, and gr ratio's will be higher, because high torque will be flying your heli's not rpm
Wally

Hmm.. I couldn;t see the point of most of what you sad there.. because it was what I said.. Build the heli around the engine but build it right..build it well but simple and build it so it don't need upgrades.. don't even offer them because they are not needed. But when designing the heli tale soem time for a change to think about wiring runs and plumbing not leave it to folk to find a way to stick the bits on so you can't get at them.

To be fair to MinAir they did design the G around the trm 231 and did work on a GR for tha engine.. whether you agree that they got GR right is an entirely different matter. If they then want to proote a different power plant then redesign the machine, GR etc for any new powerplant that gets developed.

LOWER RPM

Why? I still dont see that lower RPM is some holy grail. Whether you fly on torque or not you still need combustion cycles to give the power.. it's burning fuel and the expanding combustion that provide your energy.

I'm a dumb vet not an engineer but if you want a racing animal you design it around long limbs, light weight and a huge pump capable of responding fast to changes in demand AND capable of ticking over at 60 rpm but upshifting to 300rpm for as long as you can pump fuel, keep it cool and suck the sir in and move it around.. you can keep that going as long as you can shift the combustion products: Thats why you can manage huge bursts of speed for a sprint but have to cut back on speed for the marathon or you will cook yourself and clog up with waste.

They may be 4-stroke but F1 race cars run at what? 18000 rpm burning gas and can manage bizarre acceleration without huge engine capacity (relatively)

To make a 3D heli I suppose the choice is a heavy flywheel to compensate for rotor load or make an engine that weighs less and gets it's consistent power output by 'continuous' combustion cycles so it's less dependant on flywheel mass?
.

pgk

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12-31-2009 02:27 PM  7 years agoPost 149
rbort

rrProfessor

Franklin, MA - USA

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RPMs

It may be very possible that Wally went out and tried higher rpms already with Cody and they found out that things work much better for the helicopter at the rpms that I run in mine.

I've been asked several times what rpms I run and why I don't run faster rpms but I always felt that running with the torque where I'm at was the better way for my gassers and he may have just come around to that same conclusion.

Having a constant headspeed using the motor's torque makes the machine perform better and more consistant in my opinion.

-=>Raja.

MA 1005 Hanson 280, 4142 flts
Spectra 27 3DMax, 3210 flts
Whiplash V1 Hanson 300, 1440 flts
Whiplash V2 Hanson 300, 207 flts

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12-31-2009 02:51 PM  7 years agoPost 150
pgkevet

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Wales

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RPMS

I wasn't referring to the engines we have. I was referring to the statement that gasser engines should run on torque at lower rpm.

The fact that the engines currently out there might perform best like that doesn't necessarily mean that's the way to go..and i was trying to understand the reasoning behind his statement.

pgk

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12-31-2009 03:28 PM  7 years agoPost 151
Justin Stuart (RIP)

rrMaster

Plano, Texas

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I'm a dumb vet
You can't become a vet if you're dumb.

Avant RC
Scorpion Power Systems
Thunder Power RC
Kontronik Drives

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12-31-2009 03:47 PM  7 years agoPost 152
AceBird

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Utica, NY USA

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to think about wiring runs and plumbing not leave it to folk to find a way to stick the bits on so you can't get at them.
There is a multitude of electronic devices from many manufacturers that have their inputs and outputs in different locations. You want the heli manufacturer to accommodate all the options. Features increase production cost. You pay as a consumer for including all the features that you don’t use. That is not what I want.
it's burning fuel and the expanding combustion that provide your energy.
True statement, BUT what your missing is that as the RPM,s go up for an IC engine efficiency goes down. How does that happen you say? The energy that is produced comes in two forms, mechanical and heat. We only want the mechanical and the heat is waste. When you speed up the engine you get more heat and less mechanical which takes more mechanical to get rid of the heat out of the fuel you burn. It is not just burning more fuel like you say.

I am sorry but you have to grasp what the speed torque curves are all about in order to understand what makes a heli tic.
gets it's consistent power output by 'continuous' combustion cycles so it's less dependant on flywheel mass?
First of all the purpose of the flywheel is to smooth out the impulses of the IC engine. It has nothing to do with the rotors. The rotor system has far more inertia then the flywheel. Because of the plastic gears and the lash required the inertia of the rotor is not locked solid to the crank. So the rotor inertia alone does not make a good flywheel. I can see where the prop mass will work for an EI engine on a plank but I don’t have much faith in EI for helis. Time will tell if my concerns are valid.

Ace
What could be more fun?

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12-31-2009 03:53 PM  7 years agoPost 153
AceBird

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Utica, NY USA

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I don’t have much faith in EI for helis
I guess I should clarify this statement. I don't have much faith in EI engines without a flywheel mass. That mass could be in the form of the fan and/or clutch system mounted to the crank.

Ace
What could be more fun?

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12-31-2009 04:10 PM  7 years agoPost 154
pgkevet

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Wales

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There is a multitude of electronic devices from many manufacturers that have their inputs and outputs in different locations.
Servos, gyros and governor sensors go in much the same place. The rest of the stuff can sit in the radio bay. The only exception here would be things like FBL 3-axis gyros.. and frankly they can go almost anywhere because they are 3-axis. I just want clear paths for with space for wire runs and spare cable..again it's not some complicated highly techical feature to do that and make some allowance for obvious variations.
When you speed up the engine you get more heat and less mechanical which takes more mechanical to get rid of the heat out of the fuel you burn.
Why? There's only so much calorie per combustion? OK you ay have more trouble shifting more total heat from more combustions per min.. but that's back to fundamental design. I don't see how that means that an engine has to run at low RPM. It has to run efficiently.. never an argument.
First of all the purpose of the flywheel is to smooth out the impulses of the IC engine. It has nothing to do with the rotors.
Did I say it had? I don't even believe I suggested this was an EI engine in my 'ideal' heli. It sorta got off topic...

As for what makes a heli tic.. well my tick tocks are still way ragged.. but what makes a heli tic is power behind the rotors and the ability to adjust their angle of incidence and direct a tail.

pgk

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12-31-2009 07:59 PM  7 years agoPost 155
AceBird

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Utica, NY USA

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Why?
The piston moves because of expanding gasses. The faster the piston moves the less pressure there is to move it because the piston is already moving away from the expanding gasses. The fuel burns generating a whole lot of heat energy and very little mechanical energy. That's why the torque disappears. Faster moving piston also means more heat due to friction.
Did I say it had?
I think you did.
To make a 3D heli I suppose the choice is a heavy flywheel to compensate for rotor load

Ace
What could be more fun?

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12-31-2009 09:17 PM  7 years agoPost 156
pgkevet

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Wales

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Did I say it had?
I think you did.

To make a 3D heli I suppose the choice is a heavy flywheel to compensate for rotor load
That refers to the need for a flywheel to hold inertial energy Not the rotor holding the energy.. So not what i said.. your interpretation of my grammar.
The piston moves because of expanding gasses. The faster the piston moves the less pressure there is to move it because the piston is already moving away from the expanding gasses. The fuel burns generating a whole lot of heat energy and very little mechanical energy. That's why the torque disappears. Faster moving piston also means more heat due to friction
OK I'll accept your speed/friction statement.. but whatever RPM your at the piston is moving away as gasses expand.. and presumably it compresses the gasses faster too when going the other way.. surely that is just a matter of compression ratios and back to design for an RPM range Unless your trying to tell me that 2-strokes can only operate within a narrow set rpm irrespective of design. To me that just isn't rational.

pgk

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12-31-2009 10:07 PM  7 years agoPost 157
kogibankole

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albuquerque/ibadan

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i agree with aces' last post.

This means in order to make more power, more load needs to be put on the piston in form of a lower gear ratio say 6.2 so that there is still huge pressure on the piston at higher rpms. The down side to this is that you have to be very careful with how you apply pitch, so as not to kill all the kinetic energy stored in the blades. Too much pitch at a higher rpm will kill the headspeed at an exponential rate.

I also prefer to run lower engine rpms at higher torque because im very sure that it helps to reduce engine vibrations.Lack of load these G26's result in a pissed off engine. I know this because at first I was running a 12T pinion on my predator at 14K on my 3D max. The result was broken bolt heads on the ESS aka violetnt high frequency vibes. I now run a 14T with much better results, and im even thinking about using a 15T once the engine has its 6th gallon thru it. My flying style is all out 3D with very careful collective management, and it works ! I love the stock can muffler because of all the mufflers I have used, it is the easiest to listen to when backing off the collective as the engine gets over loaded.

I am in the process of converting my spectra 7.15 to swing flybarless 810 RT CF blades. Would like to try a wally engine as well.

if im not blade bogging youll find me pack puffing

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12-31-2009 10:56 PM  7 years agoPost 158
pgkevet

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Wales

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i agree with aces' last post.
We (I) got very off topic here.. I wasnlt referring to the current offerings.. but to an ideal engine.

I donlt see that Lower RPMs reduce vibration.. they just make vibrations that occur occur at lower frequencies. And (usually) for a set energy the lower frequency should give higher amplitude.. so that you ought to see any vibration as more movement in compaisn to a higher frequency lower amplitude vibe that may well cause 'fuzz' but perhaps not affect flight as much (from the vibe viwpoint)

..which brings in a whole different discusison on how the electronics cope with differeing frequency and amplitude vibrations. Indeed, as of itself, vibration doesn't matter (except where it leads to failure).. you can get threadlocks to hold for any frequency subset you want.. and for actual flight you probably get less inteference in direction and thrust (from the piot viewpoint) with a high frequency vibration rather than a low frequency vibration.

Or another way: for the same energy a thumping bass is more likely to knock you over than a supersonic (which heats you up and melts you)

pgk

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01-01-2010 02:30 PM  7 years agoPost 159
AceBird

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Utica, NY USA

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and presumably it compresses the gasses faster too when going the other way..
I guess it is time to quit. The part of the stroke that compresses the gasses is negative mechanical energy and positive heat energy.
I am in the process of converting my spectra 7.15 to swing flybarless 810 RT CF blades.
I have a bad feeling about this. IMO the frame of the G is not rigid enough to handle 810 blades. If you horse the roll I suspect you will have problems.

Ace
What could be more fun?

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01-01-2010 09:19 PM  7 years agoPost 160
C.A.P.

rrApprentice

custer park IL.

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pghevet[

Have a flu, I thought you meant good mac hing was not important[

[[quote]RAJA RPMs

It may be very possible that Wally went out and tried higher rpms already with Cody and they found out that things work much better for the helicopter at the rpms that I run in mine.
No Raja I do not think running an engine a 12,600 rpm is the answer, by a long shot, The answer is an engine that can hold a 1,800 head speed at an engine speed of 12,000 and under, It's called torque matching hp, First your heli has a gr ratio made for the 231, not for the 260, You can gr, any engine to give more torque, but you lose head speed, Which may be ok for FAI flying but not 3d, The trick and it's not a trick is to build and engine that will run lower rpms and has the torque to maintain the higher head speed for faster and crisper 3d, If you look at Cody's last video you'll see no bogging At All on the blades, and he was over his torque band, That was just under your engine rpm of 12,600, he was running a higher head speed then you and a 6.7 gr, And it held strong, As you need to run a 7.08 gr to come close to it, that's torque talking, not engine speed, What we found and as I told you was the peak performance on Cody's engine was about 12,250, Not 12,550, Your engine could not come close to that (you need a higher gr), With the new porting that Zeman will be testing, the torque band looks to be even higher to match higher hp, Wally

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