HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Jun 22, 2008, 09:52 PM
CD-ROM Junkie
Art Newland's Avatar
United States, WA, Bellingham
Joined Apr 2001
13,962 Posts
Thanks for the video corsairjock, nice flying. Looks like plenty of power on 600 watts, that surprises me. Larry and I noticed that the kit P-51 balance point is something like 3 7/8 inches and the H9 is 4 3/4, I know they are not the same planes but are about the same size.
Art Newland is online now Find More Posts by Art Newland
Reply With Quote
Sign up now
to remove ads between posts
Old Jun 22, 2008, 11:55 PM
DELTAS RULE
corsair nut's Avatar
tehachapi, CA
Joined Jan 2006
22,744 Posts
that looks like more than 600W...are you sure its not 1200? are you reading off of one pack, or both connected? my .90 TT bearcat is flying on 1500W, and its just about right...i think it would barely fly at 600-800W, im running 4 4s packs, to make a 8s 4500 setup, and reading off one side of the power connections im getting 750W, so tha makes 1500W total... in any case, sure looks like it flys great! id consider this bird if i ever lost my bearcat...(it flies way to nice to ever lose! :O) great job.
corsair nut is offline Find More Posts by corsair nut
Reply With Quote
Old Jun 23, 2008, 12:33 AM
Fly allot, Crash allot, next?
United States, CA, Corona
Joined Feb 2006
7,246 Posts
WOW, nice flying plane. Much faster than my Hangar 9 warbirds on 6S. I suspect that your watt reading is off, like Corsair Nut says, it is probably 1200 watts, not 600.

Anyhow, great flight and congrads.

Al
SCALEFAN is offline Find More Posts by SCALEFAN
Reply With Quote
Old Jun 23, 2008, 08:51 PM
Registered User
CorsairJock's Avatar
Parchment, MI, U.S.A.
Joined Oct 2004
372 Posts
Quote:
Originally Posted by MrN79
Very nice flying!
Just curious you said in your post that you didn't charge your batteries between flights? I had always read that was a bad thing to do, because the ESC always reads voltage when it's connected, that's how it determines the low voltage cutoff.
Mark
According to MotoCalc, my speed controller is drawing about 28 amps with this setup (static). With a supply voltage of about 22 VDC, that translates to 616 watts (amps x volts = watts). MAYBE MotoCalc is off a little but based on my past experiences with it: not by much.

Based on that, and if I have a 5000 mAh flight pak: I should be able to draw 25 amps for 12 minutes. BUT, I figure that it should 'unload' more than that in flight, and probably average about 20 amps. That said, 12 minutes of flight time should be no problem, with plenty of reserve and not endangering my batteries. I prefer to fly my warbirds for 2 or 3 shorter flights, rather than 1 long one. My previous 2 flights were about 4 ~ 5 minutes each, so I (correctly) figured that I had enough charge remaining for a 3 minute flight. I have a timer set-up on my Tx that only times when the throttle is set to 1/3 or higher. Thus, I am timing only the powered up time.

By now you all may have figured out that I have not actually taken any amp readings on this aircraft. I usually do, but my home-made tester still has Sermos connectors on it, so I cannot connect it to this Deans connector equipped aircraft. I will be ordering one of those $50 compact testers in the near future, and will install Deans connectors on it so that I can test this Mustang.

BUT, consider this: IF it were drawing significantly more power (amps/ watts), then I would not be able to get 12 minutes of powered flight. BTW, when I recharged my battery, it only 'took on' about 3700 mAh (according to my AstroFlite 109 LiPo charger).

Quote:
Originally Posted by Art Newland
....................... Larry and I noticed that the kit P-51 balance point is something like 3 7/8 inches and the H9 is 4 3/4, I know they are not the same planes but are about the same size.
Actually, Top Flite recommends 5 5/8", +/- 1/4", NOT 3 7/8 as you suggest. Mine is at 5 1/2".


Thanks to all for the compliments on the flight. Admittedly, it was my best landing of the day (translation: the other 2 weren't as pretty). The winds were a little tricky: a crosswing was bringing it closer to the pits when it was on final, but mostly it was a little gusty but right down the runway.
CorsairJock is offline Find More Posts by CorsairJock
Last edited by CorsairJock; Jun 24, 2008 at 05:29 AM.
Reply With Quote
Old Jun 23, 2008, 10:05 PM
DELTAS RULE
corsair nut's Avatar
tehachapi, CA
Joined Jan 2006
22,744 Posts
WOW! if thats for real, it sure flys GREAT on 600W. now that i think of it, my bearcat weighs about 12 lbs, and has 1500W, and comes off the ground at 60% power in nothin flat
corsair nut is offline Find More Posts by corsair nut
Reply With Quote
Old Jun 23, 2008, 11:46 PM
Fly allot, Crash allot, next?
United States, CA, Corona
Joined Feb 2006
7,246 Posts
I don't want to act like a smart ass, and your plane flies great, however, something doesn't add up.

1. I have similar warbirds that run on 6S, weigh less than 8lbs, AXI 4130 or AXI 4120 motors and they seem to be consistant with each other. They come out with much different real time readings than Motocalc is giving you. Motocalc is like the IRS information office, give it the same numbers and it comes up with different answers. I keep playing with it until it says what I want. LOL

2. A 5000mah battery that takes 3750mah to restore it back to full charge is pretty much done and close to ESC shutdown. Nobody gets 5,000mah out of a 5000mah battery, 80% would be wonderfull.

After you get that watt meter working I'm sure you will come up with some different readings. In the mean time, I am really enjoying watching how good your bird flies on 600 watts, if only I could emulate it with my Hangar 9 warbirds.

Hey, who knows, you might have come up with an ideal combination of plane, motor, prop. and battery, live and learn.

Al
SCALEFAN is offline Find More Posts by SCALEFAN
Reply With Quote
Old Jun 23, 2008, 11:56 PM
CD-ROM Junkie
Art Newland's Avatar
United States, WA, Bellingham
Joined Apr 2001
13,962 Posts
Quote:
Actually, Top Flite recommends 5 5/8", +/ 1/4", NOT 3 7/8 as you suggest. Mine is at 5 1/2".
I was talking about Topflite's P-51 build-up kit, not the ARF.
Art Newland is online now Find More Posts by Art Newland
Reply With Quote
Old Jun 24, 2008, 12:18 AM
Electric Coolhunter
Thomas B's Avatar
United States, TX, Fort Worth
Joined Jun 2000
14,634 Posts
He is running the milder 20 turn 4130 with a KV of 305. I typically use the 16 turn motor on 6S and that does give a more power with it's Kv of 385....the 16 turn has a 26% higher Kv than the 20.

Proves that not all 4130s are created equal.....

You can actually use 8S lipo and a 16/10 prop on the 20 turn....and that would give the power like you get on a 16 turn and 6S. The 15/12 he is using does prop up the motor a little and appears to be working well.

To me, when viewing the video, this Mustang appeared just a little milder than my H9 Hellcat with it's 16 turn/6cell/16x10 prop Axi 4130 setup.

If I were to guess, I would guess that the model is making a little more than 600 watts, though.....as Al said, Motocalc is not perfect and we have seen significant differences in prediction vs reality. with that 12 pitch prop, it would seem that you would be making a little more wattage than Motocalc is saying.

Unloaded in the air, it might be closer to 600 watts that most of us would guess.

I look forward to hearing the exact numbers from a watt meter.
Thomas B is offline Find More Posts by Thomas B
RCG Plus Member
Last edited by Thomas B; Jun 24, 2008 at 12:27 AM.
Reply With Quote
Old Jun 24, 2008, 12:22 AM
Electric Coolhunter
Thomas B's Avatar
United States, TX, Fort Worth
Joined Jun 2000
14,634 Posts
argh...accidental double post.....
Thomas B is offline Find More Posts by Thomas B
RCG Plus Member
Latest blog entry: 2014 events and travel
Reply With Quote
Old Jun 24, 2008, 01:40 AM
Fly allot, Crash allot, next?
United States, CA, Corona
Joined Feb 2006
7,246 Posts
Thomas, we're in the same ballpark. Mine are powered by AXI 4130/16, however my prop sizes are less than yours at 16 and I'm running 100 watts per pound with that setup. My Hangar 9 planes don't appear to fly as fast as Corsair's. So,

In your situation I could reconcile the difference. I would have to use the power of deduction and say that if I used a 16X10 prop I would exceed the 100 watts per pound and the planes would fly better, like yours. If I remember correctly I have 70 or 77Amp Jeti ESCs in those birds and the setups run in the 800 to 1000 watt range. As I said, at that wattage my Hangar 9 planes are not rocket ships. That is why I question 600 watts per pound on Corsair's plane and it looks like it's faster than any of my Hangar 9s.

If his wattage is correct, I want his setup on my planes, there would be no stress factor at all and I could fly 12 minutes. I could also put 6,000mah into a 5000mah battery. Sorry if I read wrong or mistated the facts, I'm old, tired and sometimes cranky....that's my excuse and I'm sticking to it.

Jim and I both filled our motor homes with diesel, then drove 500 miles to a truck stop. At the truck stop we both filled up by putting in 65 gallons of diesel. Jim said that he got almost 8 miles per gallon, I told Jim that I got 12 miles per gallon. Jim then told me that I was fired as his accountant. 15 years later and Jim won't let me forget. That is why I use a watt meter and tach to verify the power setup.

Al
SCALEFAN is offline Find More Posts by SCALEFAN
Last edited by SCALEFAN; Jun 24, 2008 at 09:25 AM.
Reply With Quote
Old Jun 24, 2008, 09:40 PM
Electric Coolhunter
Thomas B's Avatar
United States, TX, Fort Worth
Joined Jun 2000
14,634 Posts
The real numbers will indeed tell the real story and I do hope he publishes them here in the thread.

My point overall was that is not a deep enough analysis to say that a 4130 powered model on 6 cells should or should not work well at certain amp levels without discussing the exact version of the motor, the prop being used and other important details. For instance, a P-51 is a little cleaner model than a Hellcat and would go a bit better on slightly fewer watts, all else being the same. There are SO many variables.

I have been so happy with how my larger models fly that I have rarely ever applied the wattmeter, in spite of my best intentions to get numbers. So, I understand Corsair Jock not getting to it, yet!...
Thomas B is offline Find More Posts by Thomas B
RCG Plus Member
Latest blog entry: 2014 events and travel
Reply With Quote
Old Jun 24, 2008, 09:46 PM
Registered User
CorsairJock's Avatar
Parchment, MI, U.S.A.
Joined Oct 2004
372 Posts
Video of my slo-mo/ staggered operation retracts:
Top Flite 1/7 scale P-51D Mustang ARF Slo-Mo Retracts (0 min 29 sec)
CorsairJock is offline Find More Posts by CorsairJock
Reply With Quote
Old Jun 25, 2008, 12:22 AM
Slick Gunner
Honolulu Hi
Joined Jun 2005
21 Posts
Topflight P-51 ARF

Very neat retract setup. Did you need any down and right thrust correction
on your axi mount?
myung is offline Find More Posts by myung
Reply With Quote
Old Jun 25, 2008, 05:24 AM
Registered User
CorsairJock's Avatar
Parchment, MI, U.S.A.
Joined Oct 2004
372 Posts
Quote:
Originally Posted by Thomas B
...................... a P-51 is a little cleaner model than a Hellcat and would go a bit better on slightly fewer watts, all else being the same. There are SO many variables.............................
Well put. In FACT: the P&W R2800 produced about 25 ~ 30% more HP than the RR Merlins. In other words: Full scale Corsairs and Bearcats had more horsepower than Mustangs, yet all had approx the same top speeds (Bearcat of course, being smaller and lighter, was fastest). The Mustangs acheived their speed (and range) with aerodynamically cleaner airframes, NOT brute HP.


Quote:
Originally Posted by myung
Very neat retract setup. Did you need any down and right thrust correction
on your axi mount?
No. I beleive Top Flite engineered the firewwall to have some offset: I just bolted the AMM500 to the firewall and the AXI to the AMM500.

I should have my watt meter by July 4, and I WILL post results. I'm still betting on MotoCalc being correct tho, within 10%. I have tested other setups against it, and it has always proven to be fairly accurate to me. One more thing: I pay attention to the efficiency data. MotoCalc shows my setup to have better than 80% efficeincy at full throttle. I'm betting than many of the over-amped AXIs are getting closer to 70% at full throttle. If so, that means that I am getting about 10% more OUTPUT watts than others.
CorsairJock is offline Find More Posts by CorsairJock
Last edited by CorsairJock; Jun 26, 2008 at 06:14 PM.
Reply With Quote
Old Jul 10, 2008, 06:16 PM
Registered User
CorsairJock's Avatar
Parchment, MI, U.S.A.
Joined Oct 2004
372 Posts
Recieved my "Watt's Up" yesterday, connected Dean's connectors to it, and tried it out today.
For those that are not familiar with the "Watt's Up":
http://www3.towerhobbies.com/cgi-bin...7&I=LXLMV0&P=K
I would have ordered the AstroFlight version, but they were not in stock at the time.

With a full charge on my 6S, 12C, 5000mAH Lipo setup, current draw was about 28 amps (varied slightly above and below), indicated watts was about 650.
This again with an AXI 4130/20 swinging a 2 blade APC 15 x 12.

I'll be at the Mid America Electic Fly-In this coming Sunday (event runs Sat & Sun, but I have to work on Sat.), near Ann Arbor, Michigan, and will be happy to prove my claims there. Looks like MotoCalc was RIGHT ON!
CorsairJock is offline Find More Posts by CorsairJock
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Top Flite GIANT P-51D ARF Sture Smidt Electric Warbirds 16 Jul 18, 2008 11:18 PM