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Old Oct 08, 2012, 12:54 PM
Watts is where its at!
racerxky's Avatar
United States, WA, Seattle
Joined Oct 2004
1,733 Posts
I was gonna say, Azhar keeps telling me about the 25x12 3-blade and I should have listened by now!
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Old Oct 08, 2012, 12:56 PM
Huckfest or bust!
cryhavoc38's Avatar
United States, WA, Woodinville
Joined Mar 2007
8,057 Posts
It was pretty darn quiet but lacked oomph. Maybe your suggestion of a 25x12 3 blade would give back enough rpm to bring power back.
Certainly couldn't hurt on the downlines. The Edge drops like a rock with the 2 blade not giving much downline braking.

Wonder how that Fuchs 2 blade would work out
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Old Oct 08, 2012, 02:45 PM
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leespaddock's Avatar
USA, WA, Redmond
Joined Aug 2010
231 Posts
Quote:
Originally Posted by cryhavoc38 View Post
25 ft at about 2 or 3 inches off the ground.
A plane at MARC can't be any higher than 90db at that 25ft distance.

I've known my da100l on cans with the vess 27b rips when in the air but I knew I was on borrowed time until someone came up to me with the sound meter.

I'll prolly go with a 26x12 3 blade mej.
Tims 26x12 PT models just didn't have much oomph, but it sure was quiet and slowed the plane down on the downlines. Given its price though, I may just pick that up from him. However a vess 27c might be the trick
Quote:
Originally Posted by furballll View Post
ouch thats a hard test to pass for sure, for schlits and giggles have them test it with the ama standard imac test with the tester on a tripod and with no one near to creat an echo and see how it is.

http://www.modelaircraft.org/UserFil...Aerobatics.pdf

page 2 and 3 deal with sound testing in the ama official competition rules, 90 db is a harsh limit for sure and yoiu guys are right trying to stay below that can be very pricey.
Here is a excerpt paragraph & a link to MARC own rules discloser regarding sound level testing. (SOUND TESTING AND CERTIFICATION PROCESS / The Test Procedure. The sound meter will be used in the “A” weighting position. Position it 25 feet from the model in the plane of the prop at a height of 2-3 feet and with no noise reflecting objects within three feet. Point it directly at the model and have the engine run at full power.) http://www.mar-c.org/sites/default/f...undProgram.pdf

Great rules catch Furball based on AMA competion rules.

If "Steve the Red Hat" had the test meter 2 to 3 inches off the ground as Cry indicated then his test was non-compliant. Furthermore "no noise reflecting objects within three feet" (I also would interpret this as "including persons holding testing meter") The meter needs to be on a tripod. His test was non-compliant & invalid based on MARC's own rules & testing guidelines.

Also what isn't disclosed in the MARC's rules is the frequency, the DB test measuring equipment must be calibrated. A technicality which is also used in court to invalidate faulty radar measured speeding tickets.

I am all for rules that promote safety, welfare & protect the future of the airfeild. I am certain that the spirit of the MARC sound rules have good intent. What I dislike are rules that can be potentially or inadvertently manipulated to discriminate against "one class / sector of model aircraft or pilot style."
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Old Oct 08, 2012, 02:48 PM
Huckfest or bust!
cryhavoc38's Avatar
United States, WA, Woodinville
Joined Mar 2007
8,057 Posts
maybe I am misremembering..perhaps he was 2-3 ft off the ground. I don't remember exactly.
Lee or Kody, what did you remember? Was he ultra low to the ground or was he 2-3ft off the ground?

Ah that is interesting. The tester is a reflective object.
Yeah, a tripod should be used.
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Old Oct 08, 2012, 02:59 PM
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leespaddock's Avatar
USA, WA, Redmond
Joined Aug 2010
231 Posts
Quote:
Originally Posted by cryhavoc38 View Post
maybe I am misremembering..perhaps he was 2-3 ft off the ground. I don't remember exactly.
Lee or Kody, what did you remember? Was he ultra low to the ground or was he 2-3ft off the ground?

Ah that is interesting. The tester is a reflective object.
Yeah, a tripod should be used.
It's seems like the tester was kneeling.
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Old Oct 08, 2012, 03:38 PM
Huckfest or bust!
cryhavoc38's Avatar
United States, WA, Woodinville
Joined Mar 2007
8,057 Posts
Quote:
Originally Posted by leespaddock View Post
It's seems like the tester was kneeling. I say foul / re-test, re-test!

Frankly, I am not 100% certain as I was concentrating on deflecting as much sound as I could away from the DB measuring tool. lol
and I thank you for that!

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Old Oct 08, 2012, 06:54 PM
lost in the addiction of flyin
furballll's Avatar
Canada, BC, Kelowna
Joined Dec 2009
767 Posts
ah crud what did i start....................


in all seriousness though, yes the tester is a reflective object and will foul the results, all tests should be done on a grass surface(it absorbs probaly 2 db already at 25 feet). if you really want to cheat the system make sure your up wind of the tester.

as for a db measuing tool you can download an app for most iphones that is legal as a testing device here in canada as per the motor vehicle guys so everyone should have one on thier phones.

when our club was first setting up testing rules at the new field the guy that stepped up to lead the testing ignored all the info i sent him and the test he "developed" was useless on anythign that was above a 90 size plane really. he had the tester walk around the plane on a painted circle and they took the max reading no matter what as pass or fail. the big gass planes couldnt be run at full throttle with the two posts in the ground for the time it took to do the test without overheating. finding the ama test cured alot of the whinning and crying at our field, it gave every one a standard test that was well designed. looks to me like the test at your field is very close to this test.(very good to see)

at our electric only park flyer field we had we banned pusher planes and zaggis for how noizy the props are on them as well.


on a side note i am looking at picking up a 50 cc power system to drive my dle 55 ignition and power my radio system is that bec you were mentioning earlier good for that size as well? i bought a damaged 88 inch aw edge 540 with motor but no gear in anymore.
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Old Oct 08, 2012, 09:41 PM
aka JetMan Joe
MCSGUY's Avatar
Joined Feb 2010
2,490 Posts
Happy Halloween!
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Old Oct 08, 2012, 09:48 PM
Registered User
GotballsP-38's Avatar
United States, WA, Bothell
Joined Jan 2007
151 Posts
Quote:
Originally Posted by racerxky View Post
I forget everyone's name so I'm fine with everyone abusing mine!

(all those not interested in baking cookies can safetly ignore the rest of this post)

Someone (who's name now escapes me ) was asking about the Aurora 9 and gas kill switches. It's been a while since I really dug into this but I needed to for the 30cc project. Also there have been some questions about the RCEXL kill switch possibly being the root cause of some crashes at our field. So here is what I found out:

On the A9 + Opto Kill issue:
"After extensive research and testing it has been determined that the unexplained lockouts, experienced by some users of the Optima receivers, were caused by RF interference generated by ignition modules used in gasoline engines and not the optical kill devices as original believed."
This is the official statement from Hitec. The interference caused a reboot which effectively killed the airplane. They did a patch to the Rx software that deals with the brownouts caused by interference by quickly re-booting the Rx. I have to assume this is interference on the power lines causing a brown out as the switches in use had opto isolated signal lines. There is a very useful post on this here: http://www.rcgroups.com/forums/showp...6&postcount=80
This kind of issue isn't really A9 specific, we should all be worried about this.

On the RCEXL:
It apparently has 2 inputs. One for power and one for the signal for the switch from the Rx. The power lead can pass interference back into the Rx if they are electrically connected together as, apparently, that lead is not filtered. That means the switch is only "isolated" if you are using it with a separate ignition battery. If you plug both leads into the same power bus, regulator or battery you are not isolated. A post here covers this in some more detail and aparently has some pics from the manual.
So there is nothing wrong with the RCEXL, it just can't be used as an "ignition battery eliminator". On the small 30cc stuff we dont want to have an additional ignition battery so the RCXEL is out.

So, what should we be using? I'm going with this: the Tech Aero Ultra IBEC
It's got a practically glowing thread going over on Flying Giants.
It has a combined power + signal input lead that you plug into the Rx. All the lines (power and signal) are filtered. The signal lead is also opto isolated but the power leads (obviously) cannot be. It gets bonus points for having the signal LED like the Smart Fly system has so you can see what the ignition is on externally. I've ordered one for my 30cc project.

This is roughly the same as the Smart Fly Comp 12 + optical ignition cutoff. In my 100cc setup I run the ignition off the power bus on the Comp 12 to eliminate the need for an ignition battery. The Rx is isolated from that bus by a dedicated regulator and a filter. So interference on the power lines can't get from the ignition back into the Rx (unless you do something silly) and the signal line is opto isolated.
Interference can get to all of the servos, so there may be an issue there. I know from looking at the board that there is a filter on each individual signal line but I dont think the power lines are filtered. The Ultra IBEC may be one step better in this regard.

Hope That Helps
- Gareth
Thanks Gareth (Garreth), I was the one asking and talking to you on Sat. at the field.

Joel
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Old Oct 08, 2012, 10:57 PM
This ain't my first rodeo...
SupaTim's Avatar
United States, WA, Orting
Joined Jan 2010
1,372 Posts
Who wants to see something shiny and new!? I'm on a frikkin roll right now on knocking out projects. Apparently all the flying I've been doing stopped up the productivity...

Got the new DLE-60 running today and what a beast of a little twin! With both 23x8 and 24x8 Xoar props low idle is still smooth at 1400 rpms, saw as low as 1200 but started to shake pretty good. 23x8 turned up to almost 7k and with the 24x8 only dropped a few hundred to the 6500 range. Seems to handle the extra load just fine but the 23x8 was soooooo much snappier. Gonna try and button it all up tonight for possibly a maiden tomorrow...

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Old Oct 08, 2012, 11:31 PM
kody'd'punk's Avatar
Seattle, WA
Joined Feb 2002
822 Posts
That is awesome Tim!

How does it sound?

K
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Old Oct 08, 2012, 11:45 PM
This ain't my first rodeo...
SupaTim's Avatar
United States, WA, Orting
Joined Jan 2010
1,372 Posts
Actually sounds really good considering I've only run wood props on her. Seems quieter than my 55 on a slimline pitts. Will have one of the hats DB me someday...

Maybe I need some air but does this cowl look happy to see me?!

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Old Oct 09, 2012, 12:27 AM
Thread Crapper
JohnVH's Avatar
Lynden, WA
Joined Nov 2000
2,830 Posts
thats cool, whats the width measurement to the tops of the plug caps? if you have time.
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Old Oct 09, 2012, 12:37 AM
This ain't my first rodeo...
SupaTim's Avatar
United States, WA, Orting
Joined Jan 2010
1,372 Posts
10 3/4", just way too wide for pretty much every 50cc plane out there. Vitter and I were talking about stuffing one of these inside a 50cc AJ slick but even that monster cowl is EXACTLY 10 3/4" at the widest point. that's part of why I'm "experimenting" on the 33% Aeroworks 260. 96" WS and should come in around 20#. Won't be overpowered but shouldn't be too bad. More of a test bed for the engine at this point.
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Old Oct 09, 2012, 01:15 AM
aka JetMan Joe
MCSGUY's Avatar
Joined Feb 2010
2,490 Posts
Yep, I admit it, I'd cut holes in the cowl and let the heads stick out in the breeze. Not very classy but the mo power the mo better
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