Author Topic: New electric twin under construction (Read 5568 times)

Bob Hunt · « **on:** February 27, 2007, 08:02:24 AM »

Hi all:

Just thought you might like to see the beginnings of my new electric twin design. Hopefully the photos will attach and you will be able to see what I did last night. I built the basic wing structure in the Lost Foam method. The wing has 620 square inches of area and spans 58 inches. The nacelles will attach at the point where the two tapers meet out on each wing panel.

The model is tentatively named "Ohm's Outlaw" but that could change...

It will be powered by two E-Flite Park 480 motors (910 KV), and both of them will run off of one Thunder Power 4200 mAh Li-Po battery pack. There will be one sequencer for both motors and each motor will have a Phoenix 25 speed controller.

Later - Bob

John Miller · « **Reply #1 on:** February 27, 2007, 11:01:14 AM »

Bob, this looks good. I am interested in how you cut the foam to handle the double taper. Very clever. Twins are perfect candidates for electric. I've one of my own on the drawing board that I hope to stea---- er, borrow ideas from you on.

Hope you continue the updates on your progress.

Bill Little · « **Reply #2 on:** February 28, 2007, 07:47:20 AM »

HI Bob,

Looking forward to seeing your progress! For us electric dummies, can you give an approximation of the corresponding glow engine size of your electric motors?

Thanks,
Bill <><

RandySmith · « **Reply #3 on:** February 28, 2007, 10:49:06 AM »

Quote from: Bob Hunt on February 27, 2007, 08:02:24 AM

Hi all:

Just thought you might like to see the beginnings of my new electric twin design. Hopefully the photos will attach and you will be able to see what I did last night. I built the basic wing structure in the Lost Foam method. The wing has 620 square inches of area and spans 58 inches. The nacelles will attach at the point where the two tapers meet out on each wing panel.

The model is tentatively named "Ohm's Outlaw" but that could change...

It will be powered by two E-Flite Park 480 motors (910 KV), and both of them will run off of one Thunder Power 4200 mAh Li-Po battery pack. There will be one sequencer for both motors and each motor will have a Phoenix 25 speed controller.

Later - Bob

Hi Bob

Awesome ideas, the twin engine is one of the first things that hit me when I saw the electrics....finally we have most ALL of the problems solved by electrics that plagued the twins with IC motors, starting synchronized power output, cutoff times, power tweeking, fuel delivery problems...ie twin tanks bladders etc, are a non issue for the electric motors on a twin, there are more but these are the main problems I saw.
I will look at this with great interest. I love the idea of being able to use 1 battery to power the twin beast too! not to even mention that you can locate it where ever you want ..

keep it up

Regards

Randy

Randy Powell · « **Reply #4 on:** February 28, 2007, 10:51:37 AM »

And counter-rotating props. Very cool.

Andrew Borgogna · « **Reply #5 on:** February 28, 2007, 11:06:34 AM »

Bob,
I have a question for you, other than the undeniable "cool" effect of a twin is there any practical reason for a twin? I guess I am trying figure out if there is some problem that only a twin will address correctly. Anyway I too look forward to watching the progress of this project.
Andy

RandySmith · « **Reply #6 on:** February 28, 2007, 11:59:08 AM »

Quote from: Andrew Borgogna on February 28, 2007, 11:06:34 AM

Bob,
I have a question for you, other than the undeniable "cool" effect of a twin is there any practical reason for a twin? I guess I am trying figure out if there is some problem that only a twin will address correctly. Anyway I too look forward to watching the progress of this project.
Andy

HI Andy

I am sure Bob will reply on why he chose a twin, but the twin motors will negate several factors of singles if done right, Gyroscopic precession , spiraling slipstream , engine torque just to name a few can all be negated by a twin engine configuration

Randy

Bill Little · « **Reply #7 on:** February 28, 2007, 03:16:44 PM »

Hi Bob,

That looks sharp!

How about the engine/motor question I asked?

Thanks
Bill <><

Andrew Borgogna · « **Reply #8 on:** February 28, 2007, 03:56:35 PM »

Randy and Bob
Thanks for your response yes that does make since what you described. I noticed in one of my many model airplane mags. I get that a few electric R/C flyers are using counter rotating props that are driven I believe by two motors using what I can only guess is a shaft within a shaft. Would a set of counter rotating props also solve the problems you have described?
Andy

Bill Little · « **Reply #9 on:** February 28, 2007, 04:00:33 PM »

Quote from: Andrew Borgogna on February 28, 2007, 03:56:35 PM

Randy and Bob
Thanks for your response yes that does make since what you described. I noticed in one of my many model airplane mags. I get that a few electric R/C flyers are using counter rotating props that are driven I believe by two motors using what I can only guess is a shaft within a shaft. Would a set of counter rotating props also solve the problems you have described?
Andy

Maybe that was the reasoning behind Randy's homebrew .65 several years ago that used counter rotating props?? The rear one was "fluid" driven, IIRC.

Mike Palko · « **Reply #10 on:** February 28, 2007, 04:03:31 PM »

Another benefit of a twin is the increased prop disc area. The increased disc area will help keep speed constant up and down hill. Trike gear can be an advantage also.

Looks great so far! I will be watching this one. I am waiting for the mold breaking designs of the future!!

Keep us posted.

steve pagano · « **Reply #11 on:** February 28, 2007, 06:41:54 PM »

Man i love twin planes!

keep us posted on the progress pleeeaaassseee

roger gebhart · « **Reply #12 on:** February 28, 2007, 07:12:23 PM »

Super sleek design. Can't wait to see more.

Vincent Corwell · « **Reply #13 on:** March 01, 2007, 01:25:35 AM »

Bob

Congratulations again, you have created a great interest here

Please some more info:
battery voltage?
will you use a single timer?
a standard commercially available timer , Zigras?

The overall concept is awesome

Vincent

Dean Pappas · « **Reply #14 on:** March 01, 2007, 01:52:18 PM »

Hello Vincent ... Hello All,
The setup in the twin will use a single 4-cell battery located just in front of the wing. At this point, that means a Thunder-Power Pro-Lite
4200 mA-H battery. The timer will be of our own manufacture which we hope to sell soon. Actual;ly we are in the process of hashing out some business stuff. A JMP or Zigras timer will do nicely, you just have to make sure that the timer produces a stable and easily settable output pulse width to control the RPM setting of the ESCs. The motors will both get an idividual ESC, as this is necessary for reliable brushless operation. Some folks have gotten away with running two brushless motors from one ESC, but it is risky! The ESCs are Castle Phoenix 25s with the HI-range helicopter RPM governor mode turned on. This means that both motors will be running at the same RPM, and the outer prop will likely have to be twisted to have maybe an eighth of an inch more pitch ... kinda like tire stagger on a circle track. If you want grief, try putting more pitch on the inside motor: it'll be like running tons of right-thrust and you'll never find a leadout position that works.

Come take a look at the electric Stunt forum here at Stunthangar.
Hope that answers your question,
Dean

Igor Burger · « **Reply #15 on:** March 01, 2007, 02:45:56 PM »

>>>easily settable <<<

and what about ESC like Jeti Spin which you can independently (on left and right side) adjust for wanted rpm on ground by Prog-Box?

BTW is new software for castle CC ESC with brake already available? I have troubles to land with my small 10A CC --- all lindings look like rock falling from sky

Dean Pappas · « **Reply #16 on:** March 02, 2007, 01:55:22 PM »

Hi Igor,
The new software is not yet available from Castle. I am assured that it is coming and of course, like all CC ESCs, the software is upgradeable from your PC when the boys at Castle release the new code.
Of course you can set one ESC for 1 or 2% faster than the other, I just prefer doing it with one timer and having the RPM on both motors track throughall maneuvering load transients. Mostly it's because I'm simple-minded. How fast is the governor loop on the JETI? We are looking for under 0.3 S for most of the settling to a step disturbance as demonstrated in Erik and Bruno's experiments.

later Friends,
Dean

RandySmith · « **Reply #17 on:** March 02, 2007, 02:21:44 PM »

Uhhmmm BOB

Is this one gonna be painted bronze?

?

Randy

Bill Little · « **Reply #18 on:** March 02, 2007, 03:22:35 PM »

Quote from: RandySmith on March 02, 2007, 02:21:44 PM

Uhhmmm BOB

Is this one gonna be painted bronze??

Randy

Randy, Vegas probably wouldn't even open betting on that one!!!

What would the Stunt World be like with out Bob's "Bronze Dogs"

?

Leo Mehl · « **Reply #19 on:** March 03, 2007, 10:12:03 AM »

Looks like a great project Bob. I have seen some of the wings you have built and they are first class. I met you at VSC one year and you sold me a tape on balsa forming. Well I finnally did a turdle deck of 3/32 balsa on a Gieskie Bear. Worked great. who says you can't teach old dogs new tricks. Keep up the good work. Leo Oh by the way I lent that tape to Dave Royer and still havn't gotten it back.

john e. holliday · « **Reply #20 on:** March 04, 2007, 07:26:35 AM »

Bob, you and Sparky are artists when it comes to constructing these airplanes. Will this wind up being a construction article in the future? DOC Holliday

Bill Little · « **Reply #21 on:** March 04, 2007, 02:35:21 PM »

Hi Buddy!

The more I look at that wing, the more it looks like the "Hunt Mustang"!

Like I said somewhere else, you don't get the credit you deserve.........

Bill <><

Shultzie · « **Reply #22 on:** March 07, 2007, 02:55:02 PM »

Hey Gang...after check on some of the OTHER website forums....

THE MORE I READ...IT WOULD APPEAR THAT "GOING ELECTRICAL BAAAANAAANA'S IS GOING TO BE THE NEXT CHAPTER IN PRECISISISISISISISION AEROBATICS for control line?
Bob Hunt...certainly has stirred up the stunt-pot!!
Way to go Robin...our RobertBobbist of Hunt-stunt-dome!!!!

Thanks for sharing this story with us and all our other neighboring forum. Communications is what it is all about....in learning more about Electrics! Some really great info sharing goin on.

Dean Pappas · « **Reply #23 on:** March 07, 2007, 09:24:44 PM »

Hey Shultzie ...
You been listenin to them old Donovan records too loud again?

Dean Pappas

Bill Little · « **Reply #24 on:** March 08, 2007, 07:27:57 AM »

Quote from: Dean Pappas on March 07, 2007, 09:24:44 PM

Hey Shultzie ...
You been listenin to them old Donovan records too loud again?

Dean Pappas

Hi Dean,

Just an aside, but I thought of Sunshine Superman when you posted that!

Donovan is Johnny Swafford's Brother from here in NC. Johnny was the QB at Carolina (North By God Carolina that is!) when I went there to play football. Kinda cool to meet a "celerbity" at the time......

Bill <><

Shultzie · « **Reply #25 on:** March 08, 2007, 08:47:43 AM »

Quote from: Dean Pappas on March 07, 2007, 09:24:44 PM

Hey Shultzie ...
You been listenin to them old Donovan records too loud again?

Dean Pappas

HUH? WAAAAAAAZZZU-SAY? Papp-n-Little!!! I wish it was only my hearing that is "goin! From too many years....workin' next to a whinin' stunt engine and windtunnel fan motors....and playing too many high notes on my Callet Jazz trumpet, combined with choro-sport kite flying with the music too loud on my headsets.
NAAA! IT'S TOUGH BEIN' 168 YEARS OLD!

Jim Pollock · « **Reply #26 on:** March 08, 2007, 03:10:16 PM »

Bob,

As soon as you win the Nats with that twin electric puppy the whole world will go nuts and start building electric twins!

Jim Pollock