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Old Nov 01, 2012, 09:14 AM
Registered User
Australia, QLD, Beaudesert
Joined Jul 2008
522 Posts
Hi again guys,
Good to see your having a blast with the planes BJ
As I often do I am probably overthingking the set up for my Siren but...
I was reading KRProton's blog on his build, which I will assume you guys have seen, I noticed that his bench testing with Ammo 28-45-3600 with 13x8 prop on 4s was about 740 watts, but later inflight test shows about 950, what is the reason for the difference of static to flight, in fact he stated a bit over for static in plane. I know KRProton is still posting,maybe he will fill me in. As I still have not ordered the motor yet as I thought that I would leave it so I decide if I would like more power, now after seeing the difference in figures, I am a bit confused!
Neal
PS KRProton does give figures for the 28-56-3200 he is running now, seems to be a bit of "cross talk" somewhere,
BTW
What sort of power are you guys running??
I would like a bit of a feel of what is being run, as this is my first plane of this type, and I am not after an absolute monster, I dont want to under power either.
I know I will get used to the power and speed. but I would just like to go with something that is considered by more experienced flyers as "something I am happy with"
As to be honest I dont know if 600 watts in this plane is considered enough or if the concensses is 800 or 900 or whatever.
As I am ready to order G/B and Ammo motor. but I dont want to buy twice, to soon!
Neal
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Old Nov 01, 2012, 03:45 PM
Tim Lampe; Hobbico R&D
KRProton's Avatar
Champaign, IL
Joined Dec 2009
3,390 Posts
Hi Neal.

First, call me "Tim."

One reason for the difference in the static Watts I first quoted (738W) vs. later figures from a flight (950W) is the battery. Those original numbers were when I used a Flight Power 30C battery. I just pulled it out of our "stash" of batteries, so can't vouch for the condition/number of cycles. My in-flight data was using a Thunder Power 65C battery. It also depends on however I looked at the data - on the bench I probably took an average of a five or ten-second blast. I don't remember, but for the in-flight data I may have taken the initial burst off the fully-charged battery. In other words, inconsistency in looking at the data (maybe).

I also posted somewhat recently the differences you get when looking at logged data. Say, between static data vs. flying horizontally vs. a vertical climb.

Not sure what "cross talk" you are referring to.

I did run the 28-56-3200 for a while, but when I realized the motor is no longer available (discontinued), I pulled it and put my 45-3600 back in.

Regarding what power you should strive for, well, remembering anything over 500W voids your warranty I believe (as I thought that was the maximum stated in the instruction manual), I sure like what I'm flying with now. It's not a monster by any means. The only time it freightened me was the first time I launched I moved the stick to full-throttle (like I do on my pylon racer planes) and it about pulled my arm out of my socket! No, seriously, I almost lost my balance when it pulled me forward! Now I give it a gentle toss at about 1/2 throttle.

The way to manage the power is just to use it in bursts - mostly while climbing vertically or at an angle. All it will do is go skyward and when you're high enough just cut the throttle. Occasionally I do perform full-throttle fly bys a few feet off the ground just for more grins (from myself and specators that I imagine are watching me but probably aren't). The Siren is an easy model to manage the throttle with - not like you have to fly full-throttle at all.

Me, I think I'd be happy with anything from around 600W - 700W to around 1000W.

Hopefully others will give you their opinions too.

Tim
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Old Nov 01, 2012, 08:23 PM
Dir. of Innovation at Alert 5
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United States, FL, Fort Lauderdale
Joined Jul 2011
652 Posts
I agree with all of it... I have the aforementioned geared setup going into my new Siren and I cant wait... With the stock wing (upgraded spars only) and the opened up/reinforced fuse, keeping it light and strong, she is going to rip!
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Old Nov 01, 2012, 08:29 PM
Dir. of Innovation at Alert 5
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United States, FL, Fort Lauderdale
Joined Jul 2011
652 Posts
On a side note... I have a Siren Wing that has been fiberglassed with two additional servos (for Flaps/Spoilers) and the additional weight made her a pig even with 700/900W (3S/4S)
56oz AUW.... So, light weight is the key to the grin factor... I did it as a little project... had fun, but I know where happiness is... if you can sneak in at less than 50oz AUW, your golden...
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Old Nov 02, 2012, 04:49 AM
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Australia, QLD, Beaudesert
Joined Jul 2008
522 Posts
Hi guys,
Thanks for the reply Tim,
Sorry about not being clear,or not taking enough time to explain properly, heavy day at work.
When I said cross talk, I meant maybe power figures in wrong part of post,thats all. I thought either that or bench testing as opposed to inflight prop stall etc.
So I am glad to see I misunderstood the post a little as it happens as with the power figures that you are getting are way plenty! I certainly won't be spending any time looking for anything with a little more power. That set-up is way enough to shut me up! Other than new firewall, some cloth around the nose and wing saddle area and of course changing the wing joiner, I do not plan on any wing mods, I am assuming that if I dont load it up with full power/ speed and extreme manouvers it will be OK, I really dont want to strip the wing down.
Any way I have now gone and ordered the motor and box, also ordered the prop spinner hub etc, so just leaves the servos, looking at some from Hobbyking with similar specs to 65 mg, and they are mg, at around the $11.00 mark each I will see what there like, ordered six and will test for the best.
Now I will sit back and wait for posty!
And thanks again Tim.
Neal
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Old Nov 02, 2012, 05:39 AM
Tim Lampe; Hobbico R&D
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Champaign, IL
Joined Dec 2009
3,390 Posts
Hey Neal,

no apologies needed.

If you make a new firewall see my post a page or so back where I posted a firewall template with holes for a GP gear box.

Or, I could just send you one I already have made.

If you want it PM me your address.

I absolutely LOVE flying my Siren. Someday I'm going to get a real hotliner all from composite with like a 14" prop and 2K - 3K power, but the Siren really has a great combination of easy flying and gliding for relaxation and power for thrills.

Tim
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Old Nov 02, 2012, 06:34 AM
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Australia, QLD, Beaudesert
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522 Posts
Thanks for the offer Tim, Iam tempted to accept, but I think I will make one myself as it is half the fun! But thanks, and I sent the pdf you loaded to my wifes work and she printed it off for me, and I shall pick up some material and into it.
I am really looking forward to this!
Neal
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Old Nov 02, 2012, 07:25 AM
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Australia, QLD, Beaudesert
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Hi again guys
I have ordered motor and box, so I can ask this without having any second thoughts!
I was having a proper look at the specs for this motor and came to the conclusion that with a 13x8 it is at the edge, in fact past it! Now I dont have a prob with that, but I assume if I was to run a 13x7 it would be a bit easier on the motor? but with a lower top end? However I will fit with 13x8 as it is ordered, I only ask this as I am new to this sort of plane/set-up.
I make the assumption that the reason too push the motor this hard isto get power to wieght, would I be correct? I am wondering how long should WOT bursts be, as in do not exceed on average!?
And if your reading this Tim, I take it you have not cooked a motor yet? For short WOT runs is this a set-up that will actually hang in there?
Neal
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Old Nov 02, 2012, 07:58 AM
The wheels touch down FIRST??
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Australia, VIC, Melbourne
Joined Jun 2009
22,680 Posts
I know I've posted this vid up before - but this is just to tease you a bit, Neal. LoL

Great Planes Siren - repair and re-maiden (raw edit) (3 min 15 sec)


Just wait 'til you fly that sucker

BJ
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Old Nov 02, 2012, 11:22 AM
Tim Lampe; Hobbico R&D
KRProton's Avatar
Champaign, IL
Joined Dec 2009
3,390 Posts
Quote:
Originally Posted by neale View Post
Hi again guys
I have ordered motor and box, so I can ask this without having any second thoughts!
I was having a proper look at the specs for this motor and came to the conclusion that with a 13x8 it is at the edge, in fact past it! Now I dont have a prob with that, but I assume if I was to run a 13x7 it would be a bit easier on the motor? but with a lower top end? However I will fit with 13x8 as it is ordered, I only ask this as I am new to this sort of plane/set-up.
I make the assumption that the reason too push the motor this hard isto get power to wieght, would I be correct? I am wondering how long should WOT bursts be, as in do not exceed on average!?
And if your reading this Tim, I take it you have not cooked a motor yet? For short WOT runs is this a set-up that will actually hang in there?
Neal
Hi Neal.

I appreciate that you’re studying the data and asking good questions.

The 28-45-3600 is rated for 40A/592 Watts constant, 70A surge current. If you look at the graph from my data logging you’ll see that, in-flight, the “most” the system will ever “see” (during a full-throttle vertical climb) is 55A. The Watts spiked instantaneously to about 770W, but settled in to around 700W – 720W for the duration of the 7 or 8 second burst.

So, never reached the motor’s max surge current (or even came very close). Don’t know what the surge Watts limit of the is, but to answer the second part of your question, I haven’t cooked the motor and don’t really expect to. Probably around 20 flights thus far (with an average of maybe ten or so full-throttle bursts lasting around maybe ten I’m guessing).

Tim
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Old Nov 02, 2012, 06:51 PM
Registered User
Australia, QLD, Beaudesert
Joined Jul 2008
522 Posts
Thanks Tim,
I probably looking a bit harder at this, than I have done with my other models.
With my heli's, thats the motor or whatever it comes with,my plane's, bolt a .91 on a .60 airframe and it goes good!
And on top of that I am excited about a larger faster plane!
Max surge watts is around 1035 watts, so I can see it is still going to make it.
Thanks for the data though, it will give me a good starting point to compare with.
Neal
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Old Nov 03, 2012, 12:10 AM
Dir. of Innovation at Alert 5
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United States, FL, Fort Lauderdale
Joined Jul 2011
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I use approx 6<10sec motor pulls...
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Old Nov 03, 2012, 01:35 AM
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Hi guysI would imagine it is not going to cook itself with motor run times like that, I think I was thinking of lot longer times, more along the lines of a normal 3d type of thing.
Neal
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Old Nov 03, 2012, 08:15 PM
Dir. of Innovation at Alert 5
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United States, FL, Fort Lauderdale
Joined Jul 2011
652 Posts
Quote:
Originally Posted by neale View Post
Hi guysI would imagine it is not going to cook itself with motor run times like that, I think I was thinking of lot longer times, more along the lines of a normal 3d type of thing.
Neal
Yeah, I did too at first, but in fact they are faster with the motor off... Just focus on full throttle climbouts to about 600<1000 feet then the good ol' hell dive and a string of energy sustaining maneuvers that both shock and awe... untill she's too pooped to pop, then another massive climbout... then some thermaling? Soaring? or Hell dives.... Lots of options...
Today I was flying her and the guy asked "Hey, I'm taking off... How much time do you have before you come in?" I said.. "I either have 2 minutes or a half hour... Haven't decided yet?"
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Old Nov 03, 2012, 10:23 PM
Registered User
Australia, QLD, Beaudesert
Joined Jul 2008
522 Posts
Hi guys,
It sounds like this is a plane I am going to really reall going to enjoy, from what you say Demon 6 that is exactly the type of flying I am into/after.
I see H/K have just realeased a similar plane to this, they say will take up to and over 800 watts, called the geronimo, will follow that, like to see build quality and some flight reports.
Neal
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