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Old Apr 10, 2011, 03:33 PM
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Quote:
Originally Posted by MikeRx View Post
Well I did a runup on 5s, 4.2x4", and the eflight 2700kv..
All was well up to about 33k when a heavy vibration developed. Promising because amps where still well under 30 and I had a lot of stick left.
I hooked up 4s and same thing. On 3s it is fine running really smooth at 28k and a measley 17a.
On 4s and 4.75x5.5 I got to 28k when the vibes hit short of full stick.
Is this a firewall thing? I'm not using spinner, but rather the eflight 3.2mm cone adaptor. I can't detect a hint of vibes untill it all of a sudden hits. I'm gonna contemplate Tim's firewall mod.
No worries.. I'm going flying in the 25-30 winds on 3s. That 5.5 pitch prop makes for some silly fast downwind passes.
Also I'm doing max elevator testing.. Using as much throw at max speed as I can get without inducing flick-spin.
(Way up high at first)
Sorry for the troubles.
The cone adapter might be bad from the Eflite, sometimes the aluminum isn't properly cut. I would figure it out soon, those vibe's will limit motor power greatly on top end, plus those vibrations aren't friendly to bearings or the plane.

I had a very slight vibration, only really noticeable in high RPM, came from the slightest of bent shaft from a bad landing on the AMMO, but it was an imbalance that was hardly noticeable. That is just physics messing with you, like a front tire in a car with a tread that is separating may come alive at 50 mph and want to shake the steering wheel out of your hand, yet can't be noticed when the conditions aren't right. Different but similar. I think you have a slight balance problem, hopefully not a shaft. I doubt more RPM are going to loosen the motor shaft or bearings, I think it's just manifesting a problem that is there that isn't noticeable at lower RPM.

Edit:Yeah, that flick-spin, not familiar with that term, but I can only imagine that was like a crazy flip I did one day with too much elevator. it will be interesting if you find a certain amount of mm is doable up to a certain speed. I usually fly at about 3-3.5mm, my middle rate. But for 150+, I may have to stay at 2mm.
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Old Apr 10, 2011, 05:57 PM
Tim Lampe; Hobbico R&D
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Champaign, IL
Joined Dec 2009
3,894 Posts
I may have damaged my brand new Neu 1110/1Y motor last week from vibration. I got the wise idea to balance my spinners on a motor without a propeller. Stupidly, I throttled it up on 3S, virtually no load. I figured if I could get the collet, back plate and cone matched up to spin true that way it certainly would run true at lower rpm. After doing three or four spinners the motor started making a faint "clicking" sound. Then I realized at around 13V (3S) it was turning around 54,000rpm. IDIOT.

I continued with a 2S battery to bring the rpm down where it would be on 3s with a prop, but the damage was aready done. The motor is on the way back to Neu now.

The TruTurn is the next best spinner and that's what I'm running on my 2-turn ARC motor in my other Rifle, but I'm going to get a few more MPJet spinners for spares for my super-high-rpm setups.

Tim
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Old Apr 10, 2011, 09:38 PM
Boggy
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Australia, NSW, Sydney
Joined Oct 2006
88 Posts
Hi MadBoris,

I tried the lights a few months ago. I was using " Tiny Bright Lights" intense landing lights. I made a strip of Foil on the Wing, and a strip of foil on the body for connection so NO wires got in the way. They looked perfect inside, and I thought I was on a winner, but once outside in the sun, I couldn't see them until the plane was about 5 meters away. Unfortunately the sun over powers the lights.. Well that was my experience..

Anyone tried a GYRO on the Rifle.. ???? I put one in, but have never successfully got it to recenter ? I am too scared to use it as not that reliable, although, it could be a faulty GRYO ?

Cheers

Boggy
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Old Apr 10, 2011, 09:46 PM
Wake up, feel pulse, be happy!
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United States, AK, Fairbanks
Joined Aug 2009
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I've thought of using gyros, too, but it seems like the constant corrections would add drag and slow you down. Without it, the plane will still follow a very straight path relative to any reference point you want due to its speed. Landing would be a little different, maybe.

Further, by the time you've got a Rifle, or any plane like it, in the air, you should have the skills necessary to make a gyro equal to dead weight. Be your own gyro, in other words... I guess it could be a little helpful on the ailerons, but some solid expo should help to soften it up and might make the gyro completely unnecessary.
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Old Apr 10, 2011, 10:04 PM
Tim Lampe; Hobbico R&D
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Champaign, IL
Joined Dec 2009
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I tried a gyro last fall. Posted all about it back then too (I might have had a video as well). Had it hooked up to the roll (ailerons). It was turned up a little high so at full-throttle straight-and-level the wings would "rock" back and forth a little, but not too bad. Holding the plane in my hands didn't seem like the gyro had much effect, but takeoff and landing were perfect--just like an autopilot. And it was quite breezy that day. I should have pursued it, but didn't feel like messing with the gain and tuning and stuff. It really works though.
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Old Apr 10, 2011, 11:53 PM
3D wing innovator
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Dallas, Texas
Joined Dec 2009
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I feel for those who have had bad luck lately.. I have been less than lucky with my first THREE.
It appears the fourth is a dandy.
Five flights in the winds this weekend generated alot of interest from those who saw.
NO BROKEN PROPS is a good sign.
I c/g strictly at 7/8" and need no elevator trim.
Max elevator pulls at 3mm are fast and confident. I have triple rates 2, 3, 3.5mm.
I will test 3.5 and 4mm next.
I found a source for possible mushiness in the way the pushrod wiggles inside the guide tube. I will expand on that after some research, but I recall many years ago using inner guide beads for the rod that made it steady and more friction free in the tube.

All said a good weekend for me. The 28mm motor comes down cool at 10 degrees over 90 ambient and the high wind has made landings easy.
I'm ready to step it up with a proper spinner and 4-5 s soon. Good times ahead!
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Old Apr 11, 2011, 12:25 AM
Boggy
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Australia, NSW, Sydney
Joined Oct 2006
88 Posts
Your on the money TP16, " Be Your Own Gyro " , just in gusty conditions, would help with the landing, preventing wing drop at touchdown.. I guess experience on approaches helps, as I certainly don't drop the wing as much as I used too.

Cheers

Boggy
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Old Apr 11, 2011, 06:57 AM
Tim Lampe; Hobbico R&D
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Champaign, IL
Joined Dec 2009
3,894 Posts
Here's that post about the gyro I was talking about. I thought I had a video, but I didn't. Just a pic...

http://www.rcgroups.com/forums/showthread.php?t=1322988
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Old Apr 11, 2011, 05:12 PM
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United States, CA, Los Angeles
Joined Jan 2011
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I'm finished bench-testing the Six-Series 1700KV on 4S so here is some verifiable results. I don't have adequate cooling to go longer on the bench, although I have not had the motor hotter than I am willing to touch, it's not getting good airflow. The Thunder Power batteries are working great, my test bench was messing up my initial battery findings under load. The battery fits real well and is pretty light, you could even have a thin ESC above it if you wanted to, like I used to.

ESC: Castle ICE 50
Battery: Thunder Power 65C, 4 cell, 1300MAH
Motor: Eflite Six Series 2700KV
Prop: 4.75 x 4.75


MAX AMPS: 48.5
MAX WATTS: 685
(700 peak for couple seconds on fresh batt.)
RPM: 30,000+ (on bench, should rise ? in air)
Voltage sag at 45 amps: levels out at about 14.2 volts then begins the slow sag.
Voltage Ripple: 6% worst ripple @ 85% throttle.

The batteries keep volts well at 45 amps, around a 12-15% drop is what I see over resting volts.

This motor and batteries are a powerful setup. Now comes finding the best prop for this in air. I'm looking to top out at 145-150 flat on short runs with good acceleration, with some nice diving speed to boot. I may be conservative with my speeds, it will be a few days until she sees flight time.

Castle Bench Run:
I initially bled off some battery juice with a slow climb to 80% power, then rested a second, then brought it up to 100% for a couple bursts which is what the numbers in the chart reflect.

Castle Log
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Old Apr 11, 2011, 05:41 PM
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Joined Jan 2011
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After the wing, what is the next weak area that needs reinforcement?

In other words, like with MikeRx's testing elevator pulls, eventually he is going to find a weak point, I'm just wondering where the next one is after wings.

For me, I probably wouldn't do too much in high G inverted loops, I wouldn't want to try and pull the horizontal stab off which could be stressed in those scenarios. But in extreme flying what's after wings, nose area?, something that can be done to the tail?

I did see the part about adding some CF tow to the nose area.
I was wondering if running some CF the length of the back part of the fuse may help sure things up.

My flying style will probably get more extreme, not knowing the limits of the plane's frame is what is holding me back from being more outrageous but I don't want to be a test pilot. I once had the plane twist wildly at high speed on a high rate elevator pull, I found some limit there but it didn't snap, I'm wondering if something twisted in the tail.

Anyone?
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Old Apr 11, 2011, 05:41 PM
Crashing into the sky!
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Auckland NZ
Joined Aug 2007
7,401 Posts
Nice testing man, Remember that RPM is what determines how fast your plane goes, not watts though

Its around 70% efficient, I would be very careful with it as its likely just on the cusp of letting the magic smoke out. See if you can jam a heatsink on the motor, and only use it in bursts to try keep it in one peice.

Consider going to a 4.5x4.1, or a 4.1x4.1 to gain some efficiency and rpm back, youll probably find your RPM climbs signifcantly (and therefore you pitchspeed may not drop much with the lower pitched prop) You'll also gain some flight time and the motor has more of a fighting chance of living a lengthy life
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Old Apr 11, 2011, 05:59 PM
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United States, CA, Los Angeles
Joined Jan 2011
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Quote:
Originally Posted by MikeRx View Post
I feel for those who have had bad luck lately.. I have been less than lucky with my first THREE.
It appears the fourth is a dandy.
Five flights in the winds this weekend generated alot of interest from those who saw.
NO BROKEN PROPS is a good sign.
I c/g strictly at 7/8" and need no elevator trim.
Max elevator pulls at 3mm are fast and confident. I have triple rates 2, 3, 3.5mm.
I will test 3.5 and 4mm next.
I found a source for possible mushiness in the way the pushrod wiggles inside the guide tube. I will expand on that after some research, but I recall many years ago using inner guide beads for the rod that made it steady and more friction free in the tube.

All said a good weekend for me. The 28mm motor comes down cool at 10 degrees over 90 ambient and the high wind has made landings easy.
I'm ready to step it up with a proper spinner and 4-5 s soon. Good times ahead!
I'm jealous because I'll be grounded for a while, sounds like fun. My grass is so bad at ripping the planes down and props that Rifle pilots at my field prefer landing on the concrete runway, me included. It took two landings in the grass before all 3 landing strips where ripped off my plane, it's carnivorous. I haven't even started renovating my bird so i will be grounded for a while, keep the reports coming, and share some inflight castle logs if you can.
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Old Apr 11, 2011, 06:05 PM
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Quote:
Originally Posted by jackosmeister View Post
Nice testing man, Remember that RPM is what determines how fast your plane goes, not watts though

Its around 70% efficient, I would be very careful with it as its likely just on the cusp of letting the magic smoke out. See if you can jam a heatsink on the motor, and only use it in bursts to try keep it in one peice.

Consider going to a 4.5x4.1, or a 4.1x4.1 to gain some efficiency and rpm back, youll probably find your RPM climbs signifcantly (and therefore you pitchspeed may not drop much with the lower pitched prop) You'll also gain some flight time and the motor has more of a fighting chance of living a lengthy life
Yeah, high watts is not a good thing, I'm not sure what this motor has to give. Amps aren't too bad though. High voltage is something I am excited about though, which is where my high RPM's are coming from.
Don't you think that some of the RPM being so low is due to it being loaded up on the bench? (I get 20,000 at under 200 watts used)
I think it's about 38,000 RPM theoretical max at about 14.2 volts, I expect this prop to unload in air and speed up just don't know how much on this slippery frame.
As it is 30,000 RPM is only like 137 MPH or something close, but I know I exceed that flat easy already Doppler'd on short runs at 145mph.
A 30% unload in power demands in air are also expected according to KRPRoton's findings.
What are some of the other high end motors producing in RPM in air or on bench?

P.S. This thing cools very well, I may put a heatsink on it since I have one incoming soon, but it has been coming down cool to the touch. WOT may change that.

Edit: Ok so I check KRProton's pdf again, he shows some of the Arc's hitting 31k,32k. The Mega's are hitting 38k-39k. Those are smaller props, 4.5x4.1 and 4.1x41.1.
So I'm thinking this may give Arc like performance in top end or more, with even better torque at this voltage and kv.
I will try some smaller props once I start flying, see how much it costs me in perf. The point you make about lower pitch being made up for with the faster spin makes sense, I have to find that sweet spot. If I smoke a $50 motor by pushing it, I can handle the $ and a worst case scenario of a dead stick. Cost of testing It is kind of cool to know it can do 700 watts without airflow.
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Old Apr 11, 2011, 06:44 PM
Tim Lampe; Hobbico R&D
KRProton's Avatar
Champaign, IL
Joined Dec 2009
3,894 Posts
Quote:
Originally Posted by MadBoris View Post
After the wing, what is the next weak area that needs reinforcement?

In other words, like with MikeRx's testing elevator pulls, eventually he is going to find a weak point, I'm just wondering where the next one is after wings.

For me, I probably wouldn't do too much in high G inverted loops, I wouldn't want to try and pull the horizontal stab off which could be stressed in those scenarios. But in extreme flying what's after wings, nose area?, something that can be done to the tail?

I did see the part about adding some CF tow to the nose area.
I was wondering if running some CF the length of the back part of the fuse may help sure things up.

My flying style will probably get more extreme, not knowing the limits of the plane's frame is what is holding me back from being more outrageous but I don't want to be a test pilot. I once had the plane twist wildly at high speed on a high rate elevator pull, I found some limit there but it didn't snap, I'm wondering if something twisted in the tail.

Anyone?
Hey Boris.

As far as total failure, I don't know what is the breaking point for reinforced wings either. One thing I like to do, just for overall durability is add come CF inside both sides of the fuse right next to the opening behind the wing where we put our receivers. Several hard landings can cause this area to develop cracks.

As far as total failure goes though, I still see the wings being the weak point (but again we don't know for certain). I can say though that I am totally content with the strength and G's it can take with a reinforced wing and the MEGA setup. Any more power/speed than this and the limit isn't how much stress the model can take but how well you can keep up with it and see it.

You'll know just what I mean when you mount up that MEGA.

Be afraid. Very afraid. I'm only serious.
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Old Apr 11, 2011, 06:50 PM
Crashing into the sky!
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Auckland NZ
Joined Aug 2007
7,401 Posts
Judging by your rpm, Id say the 6 series on 4S with a 4.1x4.1 would be the go. It'll likely be a touch faster than an ARC 28-37-2 on 3S, you should be around 34k rpm if the eflite is any good, Ive never played with one personally.

30k rpm on a 4.75x4.75 from near 700W in is an overloaded motor. Ive had 1200W going through a 33gram motor on the bench before, it survived as it only happened for a second. Doesnt really prove much in practice though

KRProtons 30% rule of thumb will be effected drastically by umpteen different factors, I wouldnt bank on it unloading by 30%.

Id start with smaller props, and then work up. At least that way you'll get some useable data, and a feel for how the motor is holding up as you increase the load. No point burning $50 just cos you can

Are you running a seperate BEC? A melted motor can destroy an ESC (and take the BEC out with it)
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