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Wrongway-Feldman 05-14-2014 05:17 PM

don't be in too big a hurry
 
Seeing as it was the first day in a very long time with only light winds I decided to maiden the FT Viggen this morning.
For bench test I had a orange 4 channel receiver in it. I thought it should be fine for the maiden as I won't be pushing it and keeping it close.
It flew so well I forgot I had the small receiver.
A couple of minutes into the flight I opened her up and boy does she move. Before this I had kept her low and slow. This is the best flying edf I've ever had. Cut the power and she glides forever. Can nearly get her to hover.
Back to the story at hand. On a high speed pass she got a little further than I meant it to and lost contact with the receiver. ESC failsafe cut the motor and she nosed in from around 150 feet.
As I start walking towards the place of impact I touched the throttle and motor spins up. Couldn't have walked more than 15 feet. Walk back to where I was originally and loose contact again.
When I got to her the only damage was to the break away nose cone. Did its job perfectly.
Moral of the story. Take the time to use the proper equipment, especially when you try to use a shorter range receiver on something that goes very very quick.

thepiper92 05-14-2014 06:06 PM

Something similar happened with my UMX SBach. Could have been some sort of interference, can't be certain, but I am guessing the little receiver/esc units in the Micros can't have the same range as my FrSky units. I was flying a fair distance away, still in view, but I couldn't have gotten much further with the SBach still in view. I started going into a dive and when I wanted to pull up from the dive, nothing. All I could do was cut the throttle, although unsure if it stopped the throttle, or if it already cut off. The front end was detroyed, luckily I found a new fuse at my LHS.

Wrongway-Feldman 05-14-2014 08:02 PM

I don't think it was interference. I am out in the middle of nowhere. The nearest cell tower is 12 miles away. Also wasn't a brownout. I was running an 70 amp opto ESC with 5 volt BEC on only 2 servos.
This was definitely a case of flying out of range. Wasn't even that far. Maybe 1000 feet. Didn't actually think it was that far till I walked out to the crash site.
It's a sizable plane and easy to see.
Lesson learned. I fly it with the frsky receiver once the nose is repaired.

kyleservicetech 05-15-2014 02:47 AM

Quote:

Originally Posted by Wrongway-Feldman (Post 948376)
I don't think it was interference. I am out in the middle of nowhere. The nearest cell tower is 12 miles away. Also wasn't a brownout. I was running an 70 amp opto ESC with 5 volt BEC on only 2 servos.
This was definitely a case of flying out of range. Wasn't even that far. Maybe 1000 feet. Didn't actually think it was that far till I walked out to the crash site.
It's a sizable plane and easy to see.
Lesson learned. I fly it with the frsky receiver once the nose is repaired.

Was that a switching mode 5 Volt BEC ???

As for cell towers, they usually run on 1.9 Ghz, quite a bit off of 2.4 Ghz. You were not near any powerlines? My son had range test about 1/2 of normal on a Spektrum DX6i transmitter, until he got a half block away from those powerlines.

It would not be interference from the powerlines, their radio noise from a bad insulator is no where near 2.4 Ghz. My guess, he was getting a reflection from those power lines.

If you're running Spektrum radios, my club members are running the AR400 full range 4 channel receivers in their 100 MPH foamie jets. Absolutely solid radio link, even when the foamie is but a speck in the sky.
http://www.spektrumrc.com/Products/D...rodID=SPMAR400

Wrongway-Feldman 05-15-2014 03:24 AM

Quote:

Originally Posted by kyleservicetech (Post 948415)
Was that a switching mode 5 Volt BEC ???

As for cell towers, they usually run on 1.9 Ghz, quite a bit off of 2.4 Ghz. You were not near any powerlines? My son had range test about 1/2 of normal on a Spektrum DX6i transmitter, until he got a half block away from those powerlines.

It would not be interference from the powerlines, their radio noise from a bad insulator is no where near 2.4 Ghz. My guess, he was getting a reflection from those power lines.

If you're running Spektrum radios, my club members are running the AR400 full range 4 channel receivers in their 100 MPH foamie jets. Absolutely solid radio link, even when the foamie is but a speck in the sky.
http://www.spektrumrc.com/Products/D...rodID=SPMAR400

It is a switch mode ubec with choke coil on the connector.
I use both frsky and orange dsm2 compatible modules in my 9XR. It's the first time I've used one of the orange 4 channel park receivers. I picked up a couple for some micro backyard flyers I was going to build. I normally use the orange 7 channel full range receivers and have never had a range problem with them. For my largest planes I almost always use the frsky receivers as I find them to be excellent.

Think I'm gonna load up a Doppler ap on the phone next time to what kind of speed I'm getting out of that Viggen. Amazing how fast and controllable 2$ of foam board can be.

fhhuber 05-15-2014 03:32 AM

I gave up on Orange RXs.... I bought 3.

One DOA.
One gives less than 25 ft range (not in range test mode) regardless of how I set things up.
And the 3rd never gave more than 500 ft useable range.

Even the lowest range Spektrum park flyer RXs do better than 1000 ft in a bad installation.

thepiper92 05-15-2014 05:35 AM

I'm using the Orange Module for the SBach. As for powerlines, do they actually reflect the signal, because I was near power lines when the plane nosed to the ground. I haven't had an issue since that one crash that totalled the front end.

kyleservicetech 05-15-2014 06:02 AM

Quote:

Originally Posted by thepiper92 (Post 948429)
I'm using the Orange Module for the SBach. As for powerlines, do they actually reflect the signal, because I was near power lines when the plane nosed to the ground. I haven't had an issue since that one crash that totalled the front end.

Good question. Hopefully someone reading this can provide more details.

My limit of knowledge is from my son who was doing range testing very close to powerlines in his back yard.

Also, it's an unknown at least to me, how well off brand receivers reject way out of frequency noise, as compared to Spektrum, JR, Futaba and other mfgs.

thepiper92 05-15-2014 06:06 AM

Well I gather the micro receivers get worse range, maybe they also accept other frequencies easier. Not something I want to happen again, especially from a loss of control.

Wrongway-Feldman 05-15-2014 12:43 PM

As I understand it these tiny little receivers don't have a very sophisticated signal gain compared to their larger counterparts. Which is understandable seeing that many of its components are combined in to single smaller chips.
The thing is I actually knew the range wasn't good when I took the Viggen out. I was just so amazed by the plane that I forgot not to go too far out.
These little receivers work very well for their intended target, small backyard flyers that don't really need the range and have limited space for a larger receiver.
This all came down to me being in too big a rush and not taking the time to swap out the Rx.

solentlife 05-15-2014 01:09 PM

Park Rx's are called that for good reason ... ;)

Very few are actually factory spec'd for more than 300m or so ... the exception is the FrSky 4ch that is rated for 1000m

Anyone flying a Park Rx to more than a park range - basically are inviting a mishap ...

Sorry to be blunt.

I do use the FrSky 4ch's in various models of mine - but only if I intend to fly reasonably close, I can lay the antenna nicely to get best reception possible ....

and again - I say - they are factory spec'd at 1000m ... and I've evidence of them working far beyond that. So I am comfortable to fly with them.

Nigel

riverrat 05-15-2014 02:12 PM

Mr Feldman

Do you have any experience with the
Viggen built in the pusher prop configuration?

Regards
Jimmy

fhhuber 05-15-2014 02:44 PM

Pusher is more efficient than an EDF. So for the same watts at the same weight (with good prop selection) you SHOULD go faster.... or you should be able to get the same performance on less watts which would allow you to carry less battery weight (for better aerobatics) or get more duration with the same RTF weight.

You have to get up over 250 mph before EDF can potentially have a speed advantage due to mach effects on the small props we use. But then the EDF rotor would probably be fighting the same mach effects. I've seen the calculations on the props. I doubt they've been done for the EDF.

solentlife 05-15-2014 03:32 PM

Example :

My 50mm EDF on over 750W gets 140kph ... 5000kv 6 blade 4S

Same 50mm EDF I have that is converted to pusher on 4.1 x 4.1 on 3200kv 4S at about 500W gets over 180kph.

Pushers and EDF's rarely get in same ballpark ...

Nigel

Wrongway-Feldman 05-16-2014 03:47 AM

Quote:

Originally Posted by riverrat (Post 948453)
Mr Feldman

Do you have any experience with the
Viggen built in the pusher prop configuration?

Regards
Jimmy

I haven't built a pusher version yet but I plan to.
By all accounts you can make it a very light slow flying pusher or a very speedy high powered one.
But as solentlife mentioned if you are looking for simply getting a ton of speed with a simpler build the pusher is the way to go.
I happened to have a 70mm edf unit in need of a home and decided to use it.
On a fresh pack it has just under 900 watts and is quite fast. But I'm very certain that if I built it as a pusher I would need only 60% of that power to get the same performance.
I've shied away from edfs for a while cause my experiences with them have been mixed. I had an a-10 that was badly under powered on 2 50mm units. I also had a couple of 50mm fighter like the f9f and t45 that only flew on full throttle and behaved like a brick with anything less.
If this design flies this amazingly well for $2 worth of foam board why can't the big manufacturers design something as good for $200?
I can't say enough good things about this design. It is simply the best plane ( of its kind ) I have ever flown.

riverrat 05-16-2014 01:23 PM

Thanks Guys!

Never built a foamy, but the Viggen looks interesting.
I got several out & inrunners laying around. And I guess
a prop saver would be mandatory?? Never used a prop
saver either.

Regards
Jimmy

Wrongway-Feldman 05-16-2014 01:42 PM

I have tried a prop saver only once. Never flew with it. As I was spinning up the motor with the watt meter hooked up I had the o ring pop off and the prop flew off. Haven't trusted them since.
I break a few props but they can be replaced.

thepiper92 05-16-2014 04:54 PM

I don't like the prop savers either. Used a prop saver on my Tuff Trainer. The mount part has a little notch that goes into the Gws prop. I broke both props, and had to go to slow fly props, which were GWS, but the dang hub wasn't the same. I reamed it out but it never stayed true unless I put a thicker o ring around the prop. Once this o ring was on, it took away any benefits of a prop saver

riverrat 05-17-2014 02:39 PM

Quote:

Originally Posted by Wrongway-Feldman (Post 948525)
I have tried a prop saver only once. Never flew with it. As I was spinning up the motor with the watt meter hooked up I had the o ring pop off and the prop flew off. Haven't trusted them since.
I break a few props but they can be replaced.

A folding prop might be something to consider on
the Viggen pusher?

Regards
Jimmy

Wrongway-Feldman 05-17-2014 02:53 PM

I've never tried or used a folding prop but I do not believe it would work in a pusher configuration. I think they only fold backwards towards the motor.

fhhuber 05-17-2014 03:13 PM

The folding props do fol;d backward, but there's no reason you can't use it on a pusher.

You might need to rig stops to prevent the prop from folding past shaft centerline to ensure it will spread properly when you spin the motor up. But that is the only potential issue I can see with it.

I have used a folder on a pusher. It didn't do what I hoped for and protect the prop from getting broken when landing. (the only reason I wanted it to fold) Broke the prop anyway, so I quit using the folder on the pusher.

kyleservicetech 05-17-2014 05:52 PM

Quote:

Originally Posted by fhhuber (Post 948574)

I have used a folder on a pusher. It didn't do what I hoped for and protect the prop from getting broken when landing. (the only reason I wanted it to fold) Broke the prop anyway, so I quit using the folder on the pusher.

I've wondered? Did you ever have trouble with a folding pusher prop, where one blade opened first, then the second blade shortly after?

That would put a violent out of balance load on the motor shaft for a split second or three. :eek: I was running 13 and 15 inch diameter folders on a tractor setup, never had a problem.

riverrat 05-17-2014 06:08 PM

1 Attachment(s)
The EZ Star #2 uses a folding prop with the outrunner.
As a pusher just turn the blades 180 deg. in the yoke.

And YES I make sure my folders are not binding, and only
quality blades.

Denny: I'll try to attach a pic of NitroBlast's china folder
throwing a blade.Attachment 175689

fhhuber 05-17-2014 07:24 PM

Quote:

Originally Posted by kyleservicetech (Post 948582)
I've wondered? Did you ever have trouble with a folding pusher prop, where one blade opened first, then the second blade shortly after?

That would put a violent out of balance load on the motor shaft for a split second or three. :eek: I was running 13 and 15 inch diameter folders on a tractor setup, never had a problem.

That is the reason you MIGHT need to make something to prevent the bladed over-folding. If one folds to where the tip passes shaft centerline it may not unfold. Some of the folding props are built such that this is impossible. Some are not.

Having the fuselage/motor to fold against prevents the prop from being able to fold too far.

thepiper92 05-17-2014 08:08 PM

I can see issues with a pusher folder as even with brake, the airflow may stop the blades from folding. Perhaps it is possible to have a pusher that would allow the blades to essentially fold in the opposite direction and have something to stop them from folding too far.


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