HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Sep 21, 2011, 08:36 PM
This is my Nemesis....
ViperZ's Avatar
Canada, SK, Saskatoon
Joined Jan 2011
2,008 Posts
Quote:
Originally Posted by bsbauman View Post
have any of yall checked this out? http://www.rcgroups.com/forums/showthread.php?t=1385632

I am considering it for flying in smaller venues (non AMA fields)
Bauman, that is the same EF1 class of my Pogo LR1A plane I've been flying. I absolutely love this plane in the air, and have been flying it the most. Its pretty darn fast as set up and is like a surgical instrument in the air. I can't get enough of it and only hope my SD 50 is like it to fly, only faster and more presence in the air

I say get one! I've been looking at various EFI kits as well.. I've really been wanting the Outrageous EF1 stick kit, however is no longer available. It should be coming out as an ARF, however I will probably settle on the ARF Eflite Shoestring once released in Nov 2011
ViperZ is offline Find More Posts by ViperZ
Reply With Quote
Sign up now
to remove ads between posts
Old Sep 21, 2011, 09:43 PM
This is my Nemesis....
ViperZ's Avatar
Canada, SK, Saskatoon
Joined Jan 2011
2,008 Posts
Okay, is a 12x14 pushing it...?
ViperZ is offline Find More Posts by ViperZ
Reply With Quote
Old Sep 22, 2011, 02:47 AM
Fill'er Up!
mattyhawk's Avatar
Oxnard, Ca
Joined Oct 2008
1,798 Posts
Quote:
Originally Posted by ViperZ View Post
...
I forgot the company I'm travelling in now LOL, I just came here to swim in the pool, not get dropped kicked into the deep end !!

"I paid to see the high diving act, I'ma going to see the high diving act..." Yosemite Sam


Yes, you did end up in the deep end, but I think you were smiling when you were thrown in.

Quote:
Originally Posted by ViperZ View Post
A 12x13 Prop increase the P-speed to 146 mph and power out put to 1725, so that may be an easy fix Heat will start to become a concern at 70A, current Max is calc to be 65.5A

Here is something crazy, if I drop the prop to a say 11x12 P-Speed increases to 152mph but watts output decreases to 1367.. Where is the pivotal point of Watts Output and P-speed chosen?
The big issue here is thrust. I find that watts are simply a benchmark value, but it doesn't tell us how fast you are going to fly. Yes, you can drop the amps and keep high pitch speed, but at a loss in valueable thrust, which is what we use to measure the force exerted against the drag of the airframe and gravity. If you do not have enough thrust to counteract the opposing forces, you will not go faster, no matter how much pitch speed you have.

RPM is always the key to figuring out power configurations and optimal props. The key is to maximize thrust without reducing RPM too much so that your pitch speed is reduced too much. How do you do that on paper? I don't know, since coefficient of drag is very hard to measure on these airframes, so I say check your RPM's and top speed while flying WOT as you adjust your props between flights.

If you change a prop to a higher pitch, keep diameter the same, and it doesn't get you any faster, you probably lost too much thrust from the RPM drop. If you increase diameter, keeping pitch the same, and you go faster, you needed more thrust to get the plane to the pitch speed.

Square props take time to build efficiency, so full thrust may not be reached til >90% of full speed is reached. That means the plane will feel like it is just accelerating like crazy and then suddenly hit the acceleration wall and stop increasing speed altogether. My SD50 doesn't do this, but my Shoestring does, it's kinda freaky.

And as a closing thought, any time you increase load, you loose RPM's, and visa versa.
mattyhawk is offline Find More Posts by mattyhawk
Last edited by mattyhawk; Sep 22, 2011 at 02:53 AM.
Reply With Quote
Old Sep 22, 2011, 02:48 AM
Fill'er Up!
mattyhawk's Avatar
Oxnard, Ca
Joined Oct 2008
1,798 Posts
Quote:
Originally Posted by ViperZ View Post
Okay, is a 12x14 pushing it...?
Oh no, that motor can handle more than that, but always take a temp guage with you.
mattyhawk is offline Find More Posts by mattyhawk
Reply With Quote
Old Sep 22, 2011, 07:27 AM
This is my Nemesis....
ViperZ's Avatar
Canada, SK, Saskatoon
Joined Jan 2011
2,008 Posts
Indeed I am smiling, or at least it was fun!


Thanks Matty, that all makes sense.... I knew there was a way to work it all out, and it seems by actual test and measurement.

LOL, Heat is becoming a issue with the 12x13, and 12x14, however it is just a warning. I have been thinking about a telemetry unit to measure this. I may run out of season for all this to happen, but we'll see Also these props are not a easily found... Is there anybosy out there that custom cuts props?

So I did all the final control throws and CG checks.... I'm ready to go with it! It will probably be this weekend.
ViperZ is offline Find More Posts by ViperZ
Reply With Quote
Old Sep 22, 2011, 10:21 AM
Fill'er Up!
mattyhawk's Avatar
Oxnard, Ca
Joined Oct 2008
1,798 Posts
Quote:
Originally Posted by ViperZ View Post
Indeed I am smiling, or at least it was fun!


Thanks Matty, that all makes sense.... I knew there was a way to work it all out, and it seems by actual test and measurement.

LOL, Heat is becoming a issue with the 12x13, and 12x14, however it is just a warning. I have been thinking about a telemetry unit to measure this. I may run out of season for all this to happen, but we'll see Also these props are not a easily found... Is there anybosy out there that custom cuts props?

So I did all the final control throws and CG checks.... I'm ready to go with it! It will probably be this weekend.
Right, you are one of our friends to the north, not as many resources to procure harder to find items there.

There are US sources though. Gotta pay through the nose on shipping...

Good luck on maiden this weekend! I pray all goes well.
mattyhawk is offline Find More Posts by mattyhawk
Reply With Quote
Old Sep 22, 2011, 10:35 AM
DFC~ We Do Flyin' Right
bsbauman's Avatar
USA, GA, Atlanta
Joined Nov 2008
14,629 Posts
Sweet Viperz!

I think it would be pretty cool to have a handcarved prop up front.
bsbauman is offline Find More Posts by bsbauman
RCG Plus Member
Latest blog entry: Nice Pic
Reply With Quote
Old Sep 22, 2011, 12:20 PM
Fill'er Up!
mattyhawk's Avatar
Oxnard, Ca
Joined Oct 2008
1,798 Posts
Quote:
Originally Posted by ViperZ View Post
Okay, is a 12x14 pushing it...?
You know viper, as I think more about it, the other option here is to forget the 8S and 12x13 prop and go 10S. With the 12x12 prop, you will probably be in the 75A area. Totally do-able on that motor. Just a thought down the road, don't want to push you as you haven't even maidened yet and you have a new set of batteries that weren't cheap.

But it is easy to add a 2S lipo pack (and relatively cheap) in series, that's what I do with my SD50... 2x 4S 5000mah 20C packs and 1x 2S 5000mAh 20C pack in series, just fit, but I had to remove the battery box support.
mattyhawk is offline Find More Posts by mattyhawk
Reply With Quote
Old Sep 22, 2011, 05:30 PM
Fill'er Up!
mattyhawk's Avatar
Oxnard, Ca
Joined Oct 2008
1,798 Posts
Hey BSB, check out the front page at 14:14 9/22 PST

Pic below
mattyhawk is offline Find More Posts by mattyhawk
Reply With Quote
Old Sep 22, 2011, 07:40 PM
DFC~ We Do Flyin' Right
bsbauman's Avatar
USA, GA, Atlanta
Joined Nov 2008
14,629 Posts
HA! Too Cool, dont think I have ever made the Featured Blogs before
bsbauman is offline Find More Posts by bsbauman
RCG Plus Member
Latest blog entry: Nice Pic
Reply With Quote
Old Sep 22, 2011, 09:51 PM
This is my Nemesis....
ViperZ's Avatar
Canada, SK, Saskatoon
Joined Jan 2011
2,008 Posts
Quote:
Originally Posted by mattyhawk View Post
You know viper, as I think more about it, the other option here is to forget the 8S and 12x13 prop and go 10S. With the 12x12 prop, you will probably be in the 75A area. Totally do-able on that motor. Just a thought down the road, don't want to push you as you haven't even maidened yet and you have a new set of batteries that weren't cheap.

But it is easy to add a 2S lipo pack (and relatively cheap) in series, that's what I do with my SD50... 2x 4S 5000mah 20C packs and 1x 2S 5000mAh 20C pack in series, just fit, but I had to remove the battery box support.
You think I could go 10s...??? The motor is rated to 7s only, and any time I model 10s it looks very bad!

Maybe I'll just play with this set up for the time being, and then next spring I'll step up to a 10s system. I will need a HV ESC, and the Scorpion 4035 or simular....
ViperZ is offline Find More Posts by ViperZ
Reply With Quote
Old Sep 23, 2011, 06:57 AM
Suspended Account
Auckland - New Zealand
Joined Dec 2010
1,554 Posts
Quote:
Originally Posted by ViperZ View Post
You think I could go 10s...??? The motor is rated to 7s only, and any time I model 10s it looks very bad!

Maybe I'll just play with this set up for the time being, and then next spring I'll step up to a 10s system. I will need a HV ESC, and the Scorpion 4035 or simular....
you will be fine on 8s with that motor and 12 x 12 maiden it and then play around with props
Adrian_M is offline Find More Posts by Adrian_M
Reply With Quote  (Disabled)
Old Sep 23, 2011, 08:54 AM
Fill'er Up!
mattyhawk's Avatar
Oxnard, Ca
Joined Oct 2008
1,798 Posts
Quote:
Originally Posted by ViperZ View Post
You think I could go 10s...??? The motor is rated to 7s only, and any time I model 10s it looks very bad!

Maybe I'll just play with this set up for the time being, and then next spring I'll step up to a 10s system. I will need a HV ESC, and the Scorpion 4035 or simular....
Sure, why not, its not like the motor will explode. The cell ratings are a reflection of workable volts for the total watts it can handle. If it is rated to handle 70A at 7S, that's 2000W. It can probably handle up to 2500W if you keep an eye on the temps. Just keep the total watts between 2000-2500W. That means max is probably around 60A on 10S. Shoot, the motor I have in my SD is rated for 7S and I push 10S through it, its doing fine.

Now that I think of it, a 12x12 on 10S will be too much for that motor... Sorry 'bout that.
mattyhawk is offline Find More Posts by mattyhawk
Reply With Quote
Old Sep 23, 2011, 03:57 PM
Suspended Account
Auckland - New Zealand
Joined Dec 2010
1,554 Posts
Nice Saturday morning here so today i will maiden the Sundowner finally got around to finishing it last night no video this time I'm using the Voltron GPS so i should be able to get a speed reading same Tsg 12x12e 500watts more and few more Kv than when i ran it on the vid (RIP) with the 400Kv motor should be interesting
Adrian_M is offline Find More Posts by Adrian_M
Reply With Quote  (Disabled)
Old Sep 23, 2011, 03:59 PM
DFC~ We Do Flyin' Right
bsbauman's Avatar
USA, GA, Atlanta
Joined Nov 2008
14,629 Posts
best of luck, I am eager to hear your flight report
bsbauman is offline Find More Posts by bsbauman
RCG Plus Member
Latest blog entry: Nice Pic
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Power system for Hangar 9 Sundowner 50 RB51 fan Power Systems 3 Apr 11, 2011 02:03 PM
Discussion hanger 9 sundowner 50 planefixer Fuel Plane Talk 57 Oct 26, 2010 08:59 AM
Cool Hanger 9 Sundowner 50 size cryhavoc38 Sport Planes 10 Feb 17, 2008 11:27 PM
Question Hangar 9 Sundowner 50? GJVO Fuel Plane Talk 0 Aug 23, 2007 03:38 PM
EDF 40/50 Brushless setups/results kd4gfy Electric Ducted Fan Jet Talk 0 Feb 20, 2005 04:11 PM