View Full Version : NitroModels 120 ultimate

09-09-2006, 12:16 AM
Hey All

I'll be starting this project by next weekend, if there is any interest, I'll post some of the Details.

The plane http://www.nitroplanes.com/ulbi12055scn.html

The motor http://www.warbirds-rc.com/Store/hett291814.html

The ESC http://www.warbirds-rc.com/Store/spt-80a-bec.html

The batteries http://www.a123systems.com/html/home.html 6S2P

I'm using a 75 watt per pound calculation because it think (correct me if I am wrong) the original rule of thumb of 100 watts per pound was developed in the brushed era, and with the greater efficiencies of these brush less motors, 75 watts per pound should do the trick rather nicely.

Let the fun begin Hee Hee Hee


09-10-2006, 10:01 PM
That's probably going to be around 11 lb. of airplane, RTF.

I don't think the motor you linked to will have anywhere near the performance you'd want for that airframe. You're going to need something along the lines of at least 1000-1100w to fly the Ultimate like it's meant to be flown.



09-12-2006, 07:52 AM

I have a plan B, but I want to see if it flys as the math says it should, I have a nice 1,200 watt motor lined up post maiden:D

I've had the chance to fly a few Ultimates (the Dave Patric's being the SWEETEST) so I should be prepared.

BUT this is a test of the A123 batteries, this Typhoon motor, this new Hi Voltage ESC, as well as my skills. I promise, Good/Bad/Ugly I will post the video of the maiden.


PS. BUMMER there doesn't seem to be much interest in this plane or it's build:cool:

Glacier Girl
09-12-2006, 08:28 PM
Hollywood, if it comes out anything like the Mustang did you will have a winner. Just gotta do something about the PINK:D

09-13-2006, 12:59 AM
Only men secure in their manhood can fly pink airplanes. ;)


09-13-2006, 02:19 AM
Only men secure in their manhood can fly pink airplanes. ;)


Or drive Yellow volkswagens!;)

09-14-2006, 06:28 AM
Hey GG

I too am hoping it comes out like the Hanger 9 P-51.

OOHH I like the pink color, I can't wait till it's finished, I'm looking forward to getting a picture of me holding it while in my Speedos:eek:

Now that's an mental image that will keep you awake at night:cool:

Hee Hee Hee


Jeff Boyd 2
09-22-2006, 12:21 PM
Keen to see how you go with this one, Brent . . The model looks fantastic for the price . .

I have a 5 3/4 lb Katana with 1000W and I could use more . . If I was building the Ultimate, I'd be looking for about 1500W minimum . . 2000W would be nice :D !!

09-24-2006, 08:52 PM
Hey All

I had to replace my home boiler before the weather starts to get cold up he in NH.

But this is where I am at, plane is built and ready for the power, I have the 12 A123 cells, 80 amp S6 ready ESC, and the motor, I have to build a motor mount and see what I have to move to get CG.

http://www.rcuvideos.com/view_video.php?viewkey=952d72e5847c4183e691 this is a video I posted, this plane will be well below the 10 pounds in the manual. If I use 6S2P it will be about 8.5, if I use 6S1P it will be 7.5, and I would like to maiden it with just 1 battery, I just don't know if I'll get CG this light.

I'll get back to it later this week


Jeff Boyd 2
09-25-2006, 03:01 PM
Hey Brent . . liked the cool vid . .

Where's the speedos . ;-)

09-29-2006, 10:25 PM
Hey All

Well the say a picture is worth a 1000 words so these will save my fingers:p


EDIT: Well I had to eat crow last night and MAN do I have a bad case of heart burn.

The best performance I can get from the power set up is as follows.

With a 13x6.5 prop, 8400 RPM, 6lb thrust, 53 MPH prop speed, 40 [email protected] 720 watts.

I will finish all the little work next week for a maiden next weekend.

I'll be drinking heavily due to my falling VERY short of my target Hee Hee Hee.

Jeff Boyd 2
10-01-2006, 12:48 PM
Brent, :eek: with your set-up, pick a very calm day for the maiden, and don't do anything too adventurous without recovery room, coz you aint got enough power to get you out of trouble ! ! :(

10-02-2006, 04:26 PM
Hey All

Well after I recovered from my hangover, I thought about what I was going to do.

I knew the plane would fly ( 6 Lb thrust in a 8 Lb 6 Oz plane) BUT that is all it would do "Just fly". Well even though it is ready to go, I'm going to hold off till this gets here

Granted it is another cheap Chinese motor, and as we are all finding out we're lucky if they do 75% of their stated spec. So if I only get 75% of this motors rating I should be OK:D


Mike Parsons
10-02-2006, 07:26 PM
I have heard good things about that motor from fellow club members. It should do well.

Jeff Boyd 2
10-03-2006, 01:04 PM
double post . . hit the wrong key somewhere . . sorry

Jeff Boyd 2
10-03-2006, 01:07 PM
Hi Brent, the motor looks real sweet ! !

By my calculations, this 286kV motor using a GOOD 6S pack that can maintain 3.4V per cell under load, that will amount to about 5,830 rpm. That's pretty low reving Brent, so I would look at the larger prop sizes for this one. Also, 6S at 3.4V per cell is 20.4V . . So 20.4V x 65A (maximum motor rating) is about 1320 Watts . . will fly it nicely, but limited vertical . . my guess. Prop it for at least 60A ! ! . . PS. you may need taller gear to spin the prop you need.

If you can go to 10S . . . it will really come alive ! ! (What the heck . . it's only money ;) )

Motor sure looks nicely made. Be keen to read your report on this one.

Cheers, Jeff

10-07-2006, 10:30 PM
Hey All

While waiting for the motor to come next week, I finished all the little details, and figured I had my batteries charged, Nothing special just taxi test



10-23-2006, 09:28 PM

After running all the numbers ( for about the 10th time), and still waiting for my motor to arive ( should be here this week) This came on the Cheap market http://www.unitedhobbies.com/UNITEDHOBBIES/store/comersus_viewItem.asp?idProduct=2143

I just couldn't pass it up.

So this motor http://www.unitedhobbies.com/comersus6f/store/comersus_viewItem.asp?idProduct=2097 with the above speed controller gives me.

@ 11S1P (A123 cells) and a 13X6 prop gives me about 13 lb thrust @ 70 Mph @ 40 amps, the AUW I expect to increase to about 9.5 to 10 lb.

So this will push the maiden off a couple more weeks, heck at this rate I'll need skis to do the maiden:p, but I'll have a better set up for the maiden.

Well, time will tell


10-24-2006, 06:10 PM
If that motor is of the same quality as the Hextronik HXT 50-52B I bought from UH, you'll be very happy with it. It's the best-looking motor I've ever owned, as far as looks, machine work, and workmanship go. It appears to be very sturdily designed and built. It also is getting good performance reviews over on RCGroups in a long running thread about it. I haven't run mine up yet.

It should turn the Ultimate into a real animal with enough cells and prop.

That's an insane price for a 100A controller, isn't it? I hope it turns out to be at least 75% as good as its specs say. It'll be a helluva bargain if so.


10-26-2006, 06:32 AM
This model looks like a nice conversion. How are you planning on installing the batteries? I guess they are in the cowl. The motor you're waiting on is 22 ounces. That'll help the CG issue.

Have you figured out how much weight is going to be needed in the nose to achieve the proper CG? I'd agree with Rick in that the model is going to need to be around 11 lbs RTF with electric.

I've never had a large conversion come out lighter than suggested by the manufacturer due to the amount of weight needed to get the CG right. I'm not sure if the weight mentioned is ever possible, no matter how it's powered.

In my latest conversion, a Thunder Tiger F8F Bearcat the RTF weight is listed as 9.9 lbs. Hogwash. That weight is pure fantasy. It took a whole pound of extra weight in the nose to get the proper CG.

I believe they can get away with listing the light weight because once you add fuel, which is usually in front of the CG, you're going to be able to get the correct CG.

10-26-2006, 02:08 PM

Funny you should ask:D I worked last night on mounting the new motor and here are the photos for it ( in work and don't have copies of the photos) http://www.rcuniverse.com/forum/fb.asp?m=4914933

I will be using 10S1P A123 batteries, the package will come out to be just about 800 G. that coupled with the prop spinner and the ESC (all in the nose) I get the CG in the manual, and according to the only other person on line who flys this plane. He said he even moved the GC back another .5 in., He said it felt nose heavy with the CG there.

AWU is 9 lb 14 oz ( far more than the 8lb 6oz I had with the other underpowered set up) but I still got the OEM's AWU.

Because the cowling is so long I was able to extend the motor mount 3 + inches beyond where it would sit with glow, this too is helping with the CG.

This power set up will be the one I will maiden it with, This is the 3rd power set up / test I have put in this plane ( here is the 2nd power set up with benchmark video http://www.rcuniverse.com/forum/fb.asp?m=4910773 ).

I should get the ESC early next week so (weather dependant) the maiden video/report will be next weekend.

I'll let you know how the #s come out once the ESC gets here (and of course benchmark video)


10-28-2006, 03:00 AM

Here is the last test of the day http://www.rcuvideos.com/view_video.php?viewkey=f74f3c285b3f6d57958d

14X7 prop using a 10S1P A123 pack. I only got 7=LBS of thrust and I want MORE:D .

I will head to the LHS in the morning and get some bigger props, I want at least a 1:1 ratio with a speed of 55 mph+.

But SSOO far everything is ice cold when the tests are done, somewhere around a 18-20 inch prop should do it for me, maiden will be next weekend. Good Bad or Ugly video will be posted:D


10-29-2006, 01:26 AM
Hey All

in the 1st segment of this video, you'll see I'm pulling 1.400 watts on this 18X10 prop, this gives me almost 15 lbs of thrust, I believe I'm ready for the maiden:D .


Maiden will be next weekend and video will follow.