vicman

My Feedback: (10)

I'm a speed freak with budget[&o]

evan-RCU

Unfortunately that is a carbon fiber looking coverING, He is using the original fiberglass fuse tutledeck. Nicely enclosed.

Gryphon

"Hi, my name is Gryphon, and I am a Speed Plane Addict.
I have been a Lover of Speed Planes for 2 1/2 years,
and with the help of the Revvers Brother-hood I hope to
make my planes even FASTER !!!
I promise no one to "tame it down a bit"(I'm single). : ( heh heh heh )

Signed: Gryphon 2/28/2008
Park Zone F-27 Stryker

p.s.
60W-70Watts didn't do it for me, gradually worked up to 1840W....still not enough.

Will soon maiden a 2000-2200W Stryker.
Hoping for 140 MPH with more drag than stock airframe.
Aerodynamic mods to begin by midyear.

MEGA 22/30/2 1770KV 2000+W
6S-5000 25C/50C
CC 125A ESC
FMA Co-Pilot
Eagle Tree 150A data recorder with almost all sensors.
Hitec 85MG
Medusa 3.5A 6V UBEC
DX7, AR7000
APC 6.5" X ???" Pylon prop



Revver Bro #213

evan-RCU

Hmmm 92A, 1800watts, 185mph prop speed. That motors rated at 70A, 1300W for 15 second bursts. Where are you going to fly it, I'd like to see it.

Gryphon

evan-RCU,

MEGA motors are severly under rated to my experience. My friends and I have been pushing them at 2 to 2 1/2 times the Amp rating without any issues.

Till now I've been running the MEGA 16/25/2 2650KV (rated for 35A) on 3S 85-100A, 4S 85-92A, 5S 100A(1 Flight at 100A 5S proved prop diameter of 5.5" made too little thrust to go above 125 MPH radared).This airframe and motor needs 4S, not 5S.
Another guy has several hundred flights on 3S 80A.

MEGA 16/25/3 1700KV rated for 30A is run at 6S 50-60A heard of 70A...Just read a report that 85A on 6S Wide Open throttle(mostly) for 3 minutes is what it took to burn it out.
Can name over a dozen guys running this at no less than 50A.

I use Constant of 1.6 for prop not 1.1, seems closer to reality in my testing of props in my size range within MOTOCalc.

**My new motor is double the size of the last one above and has 70A rating instead of 30.
% wise I'm pushing it way less given only 100-110A. I do have my fingers crossed and hoping for the best.

One GREAT thing about this application is the serious amount of air that flows around the motor due to its installation in the air stream. Also notice the large holes in front and rear besides its monster sized heat sink. High speed air flows right through the motor; they run way cooler than competitor’s motors that are fully sealed.

The motor examples above all ran warm, not hot. Some didn't even use heat sinks, some had med sized heat sink. 3 Guys had large heat sinks.
__________________
evan-RCU,

I'm a recent transplant from California and I don't have a place to fly this plane. 3 out of the last 6 years I was an AMA member, but not currently. I guess I can join again. There are no fields close to where I live.

I would be interested to meet you for the maiden flight. It will be with 3S-5000 and APC E 8X6 prop at about 800W, 14,500 RPM to keep speeds in the 80-90 MPH range for maiden. This is the prop in the picture above.

*** HELP me please:
This airframe has a bad tendency to rise (pitch up) starting from about 110 MPH even given the F-27C motor angle (revised and better than F-27B).
In an effort to help keep the plane level at high speed without the drag of DOWN elevator(either by me or Co-pilot system), I set it up for CG on stock location on 3S, but when I add the second 3S-5000 battery to have 6S,it will give me 2" forward C.G.

Here is the question: Was raising the motor 0.300” a potential benefit or mistake? Do you all agree on that?

My thinking was that the thrust line seems to be above C.G., so the added moment about the C.G. should further help me keep the nose from rising. GOOD?
Also there will be more air flowing above middle of fuse which might produce more lift. Bad?
Are both points valid?
Which will affect me more?
I am starting with the Angle of the F-27C motor and can change that by forward Zip ties.


Thank you all in advance,

Gryphon

evan-RCU

I was only pointing out the ratings, I agree the Mega motor should handle the power especially out in the airflow. Our club field requires AMA unfortunately. Now if we did this when no one else was around, who'd know right? Our "field" is behind Lowes motor speedway. Maybe later in the day on Saturday or Sunday? That's when the winds are down and would be best anyway.

Either way I'd like to see it when you fly it, looks very interesting.

I think raising the motor WILL help, I also think down elevon will not be a bad thing to get it to fly straight and level. maybe a mix from motor to elevator to increase down trim as more throttle is applied will help?

Gryphon

evan-RCU,

Thank you very much. Sorry for the delay in my reply. I was typing up something.

Although I live far away (below Charlotte), I come to Concord once per week or two.

The maiden might be in about 2 weeks at most...I hope...due to other factors.

I will definitely chat with you later in a PM.


Regarding the mix: The Co-pilot does that automatically. It uses 4 infra red sensors to keep plane level, so it gives any input needed for plane to fly level. I fly with it in the on position but have the gain control set way down so it does not fight my inputs. I don't remember using any down elevator during 125 MPH radar run 5 ft off the deck.


Thanks again,

Gryphon

vicman

My Feedback: (10)

Maybe you can make it up there on the 15th. I'm trying to pin things down Evan so we can do a pylon goof off day.

Flyboy Dave

My Feedback: (21)

....Gryphon ....Welcome to the Brotherhood of Speed Freaks....[sm=thumbup.gif]

Revver Bro #213 is yours....

Rev on, my Brothers.

>>> Edit....corrected Revver # [sm=red_smile.gif]

FLY200

Happy to find this forum!!!! I am Andy.....Fly200. I am in need of a plane......preferrably an electric that will fly near 200mph. Not pylon planes. Would be happy with 150mph too. Does anyone know such a plane....gas or electric. Oh, and I prefer it be bigger than 40" wingspan so I can see it. Just crashed my Cermark F-16 today after engine stall. Hoping to find something in a jet frame??? I keep hearing about a MagnumR or something???? Any vid.

Thanks all. I hope this forum can help me.

Fly200

Gryphon

vicman,

It would be my honor to meet both of you guys.
My ESC needed to be looked over and it is way over due for getting back into me hands. I was questioning its early cutoff...long story. Hope to have it soon.

Less than 2 hours of work left. Leave it to me to drag that out over the next 2 weeks....no, I'm not that bad.

I'll be in touch.
I would also like to go after my AMA membership renewal.

Take it easy vicman,

_____________________________


Flyboy Dave,

Thank you for accepting and welcoming me into your Brotherhood of Speed Freaks.

Revver Bro #213, I like the sound of that.
Reminds me of seeing 38,000 RPM on my Hyperion E-meter a few months ago.
{2650KV, 5S}


Have fun,

Gryphon

Flyboy Dave

My Feedback: (21)

.....Whoops, my bad....[sm=red_smile.gif]

....Victor....(vworley).....is Revver Bro # 212.

Speedy-Gonzales

My Feedback: (202)

FlyboyDave, Wouldn't it be great if we could group at the AMA National Flying site in Muncie,Indiana for a "Revver-Bro" blow-out! A 3 day event where we could all meet and tell big lies and pass out sedatives at the end of each day's flying?

phjoker

My Feedback: (4)

I think i f the AMA saw how 1/2 of us fly they would yank our cards!!!![sm=48_48.gif]

Speedy-Gonzales

My Feedback: (202)

You have a good point but the half that you are talking about does not include us....right? Can't be any worse than a Q500 or Q40 event. Even a Piper Cub will do some harm.

twinbrother

My Feedback: (7)

Hello speed racers. I just finished building my 55" wingspan Spitfire. I want to know what I can do to make it go faster. I think it tops out at about 90-100mph right now. Here is my setup:

320kv brushless motor capable over 1300 watts (max 55 amp bursts)
2x 4cell 5000mah lipo in series (30 volts)
80 amp esc
14x12 apc e-prop
7 lbs RTF weight

I'm getting about 7-8 minutes of flight time with aggressive flying with that above setup. What can I do to get more speed? I thought with the power of the motor, it would break 100mph easy. I've seen guys at the field with warbirds that go 135mph, confirmed via a radar gun. But that's gas. I'd like to get my electric going that fast. Any help or tips would be much appreciated.

Gryphon

Hi there twinbrother,

The relationship between power and speed is close to cubic.

To go 15% faster, here is how much more power a person might need:
1.15 X 1.15 X 1.15 = 1.52 so it takes just over 50% more power while at MAX SPEED to fly 15% faster.

Assuming that you now fly at 95 MPH and want to get to 135 MPH:
135 MPH / 95 MPH = 1.42 so you want 42% more speed
1.42 X 1.42 X 1.42 = 2.86 you need to nearly triple your power.

3 times the power is not ridiculous; I am running 27 times the power of what I started with. Changed 40-45 MPH to 130 MPH.
Now I'm going for 30+ times the power....call that ridiculous, be brave and keep reading.


********* To get you the best advice we need to know a little more information.

1) Can you provide us with a wattmeter reading? Borrow a meter at the field and place it in line with your battery and ESC.
Please note if that reading is with a battery fresh off of charger or one with battery that has just been run down 5%-15%(more useful I believe). Discharge in air to keep components from overheating, but fly for no more than 1/2 min full throttle (or equivalent) besides taxing. Disregard numbers on meter from first 2 or 3 seconds.

2) As needed would you be willing to change any components?

3) More info on the brand names and model numbers of your motor/battery/ESC, links will be good too if you can.
We can use that info to run simulations by looking up the resistance value for your motor and its idle current, looking up the "C" rating for your batteries, looking up the burst rating of your ESC, etc....

4) Often we push past the ratings of manufacturers because we know that they are way too conservative at times. Would you be willing to do so or you will not consider it?

5) How warm or hot do your various parts appear to you after your landings? If needed are you able to provide 2 things for your parts? a) More incoming air, b) More room for that air to exit.

6) Your tentative budget.

7) Do you want to a)fly only as fast as your current parts allow, or b)as much as your budget allows, or c)you want to get to 135 MPH in level flight with no wind even if the required budget if a little more than yours?


Answers to above questions will help you get better answers that you will be happier with. Answer what you can.


Later,

Gryphon

twinbrother

My Feedback: (7)

1) Can you provide us with a wattmeter reading? Borrow a meter at the field and place it in line with your battery and ESC.
Please note if that reading is with a battery fresh off of charger or one with battery that has just been run down 5%-15%(more useful I believe). Discharge in air to keep components from overheating, but fly for no more than 1/2 min full throttle (or equivalent) besides taxing. Disregard numbers on meter from first 2 or 3 seconds.
- I don't have a watt meter, but will be getting one on my next order of RC stuff. I will deliver the numbers once I get that test in the air and I'll follow your instructions on obtaining those numbers.

2) As needed would you be willing to change any components?
-I'm willing to change my components, but I'm also on a budget. I guess depends on the cost.

3) More info on the brand names and model numbers of your motor/battery/ESC, links will be good too if you can.
We can use that info to run simulations by looking up the resistance value for your motor and its idle current, looking up the "C" rating for your batteries, looking up the burst rating of your ESC, etc....
- brushless motor link: http://www.hobbycity.com/hobbycity/s...idProduct=4914

- lipo batteries link: http://www.hobbycity.com/hobbycity/s...idproduct=6351

- bec link: http://www.hobbycity.com/hobbycity/s...idproduct=6320

- esc link: http://cgi.ebay.com/RC-Hobby-80A-Bru...QQcmdZViewItem


4) Often we push past the ratings of manufacturers because we know that they are way too conservative at times. Would you be willing to do so or you will not consider it?
- I think I'm pushing the limits of the motor with my 14x12 apc eprop right now. The batteries and esc are not being pushed as the motor won't take more than 60amps in short bursts. To push the limits of the battery and esc, I know I'll have to get a motor that can take more amps.

5) How warm or hot do your various parts appear to you after your landings? If needed are you able to provide 2 things for your parts? a) More incoming air, b) More room for that air to exit.
- after a 4 min flight at mostly half throttle and 20% 2/3 throttle, the batteries were just barely warm and motor was slightly warm. Esc was fine. I drilled holes in the cowl and rear of the plane for air venting.

6) Your tentative budget.
- Maybe $100 more for speed. As you can see from the hardware I have, it's not top of the line, but the specs are decent. None of them are the expensive name brand stuff. The lipo batteries do rock for the price.

7) Do you want to a)fly only as fast as your current parts allow, or b)as much as your budget allows, or c)you want to get to 135 MPH in level flight with no wind even if the required budget if a little more than yours?
- I wanted to try to get an increase in speed by making adjustments to the equipment I have, such as different prop sizes. 135 mph would be great, but if it costs as much as you say it does, I don't have that kind of money to invest. I do want to get the info to consider it, both without spending the money for the speed and going all out. Maybe one day I will be able to invest that kind of moola for the speed. The total cost of the RTF plane right now is about $570, which isn't bad. However, it's a lot considering one crash could cause me to say bye-bye to it all. That's my worry.

I have read articles in the RC magazines regarding hop ups and have noticed one key element is getting a motor that handles high amps, up to 100+, for the increased power and speed. Although my motor has a similar kv rating, the amp output is considerably less. I'd like to start with tinkering with different props and trying to reduce weight and drag. I started getting into building fast warbirds mid summer of last year and looking on increasing speed on a budget. I know it's tough, but I hear there are little things that can be done to help with speed. Just don't know what they are. Throwing in a kick butt motor would be the easy thing to do, but more costly.

Thanks again for the in dept response.

Gryphon

twinbrother,


In your first post above, you said 320 KV, but your motor link shows 400 KV, that is a huge difference % wise.

Ideally we want a motor that is on the lower resistance value side within its KV class. This allows it to make more power and to run cooler.
So heavier motors and lower resistance allow us to make even more power, run cooler and be more efficient.

The hobbycity, United hobby stuff are mostly from CHINA and very often the resistance values are so HORRIBLE that they do not even give that info out.
Guess what: The motor in your link does not show that value.

I can tell you that you will not pick up much more speed from that motor. Given a wattmeter and tachometer, and how hot the motor feels we can start pushing with various props and see where you will end up....Don't expect a whole lot.

Consider a motor upgrade...really think about it. You can play with this one and spend your valuable time on it as long as you are having fun with it.
Sooner or later, you'll do the motor upgrade and then might wish that you had done it sooner. Mean while you would have spent some extra $ on props.


Till your meter arrives, ask a friend to take a wattmeter reading on your setup, tell them you have 8S(I think most meters should be good for 40V). Possible a tach reading for the RPM while you are at it.

________________________

I did read your comment on cost & crash. So I will show you how to avoid most common crashes...at least the expensive ones.

The 1 o.z. $69 solution can have its external sensor mounted under the fuse or wing and it will not show. This is the real deal and not like some of the cheesy units. FMA Co-pilot part # CPD4
http://www.fmadirect.com/detail.htm?...489&section=20
When you are confused or ready to crash, just let go of the stick and you are saved in 1 second or less, Easy enough for you?
I need to know 3 things for that:
A) Are your ailerons on same ch or two different ch? If not setup as flapperon will you change to 1 ch using "Y" cable?
B) Ans this only if ailerons are on 2 ch...Are you running 72 MHz radio or what else???
C) Are you running FUTABA Digital servos? if so a buffer will be needed.

With the above crash prevention solution, you might feel more comfortable buying the much needed motor even if it will not get you to 135 MPH, but allows you to make substantially more power. Remember the cubic rule. We can see what sort of power is needed and see what the various people’s recommendations are to get that kind of power and to keep the price low.
Without specific research, I know Hyperion makes some real good powerful motors.

_________________________

Little more random info:

When using wattmeter: log Amps, and Watts and the prop used if different than above.
Don't bother to log the Volt (under load).

1 Watt = 1 Amps X 1 Volt , But Volts read while under load { V=W/A }

Watts are units of power like Horse Power (HP).

746 W = 1 HP

The meter shows power coming out of battery, motor wastes a little in heat and the rest gets to the prop.
Simulations like MOTOCALC allow us to see what is happening with the system and also how things get changed in flight.

For example when a prop has less pitch than diameter, it unloads in air. Meaning the amps and power drops when near full speed, RPM increases some and flight duration goes up....all at cost to speed.

So a meter reading on ground is not necessarily the power you will make at high speed. But is very useful in setting up the simulation.

A 1:1 diameter to pitch ratio maintains the power at high speed to get you more speed, but gives less climbing (assuming same diameter as another prop with less pitch), shorter flight duration and motor will run warmer.


Later,

Gryphon

twinbrother

My Feedback: (7)

This is great info to consider. I will definitely check out that anti crash mechanism. That would totally be worth the cost. Will be getting back on this post once I look into a few things. When I look into motors, the only number I was looking at was KV. There seems to be a lot more too it and now I know why some cost more. That's very important info. Thanks!!!

twinbrother

My Feedback: (7)

I forgot to mention the reason why I listed 320kv was because the test conducted by hobbycity showed it was not 400kv, eventhough the manufacturer lists it as so. Here is the link to the test:

http://myhobbycity.com/showthread.php?t=345

It's the HXT 50-65B tested.

I plan on getting the fma device, but my main concern is equipment failure. On 3 separate occassions, my transmitter lost contact with my receiver for a couple of seconds. It recovered, but was still scary.

Flyboy Dave

My Feedback: (21)

Bretheren....someone start a thread "Electric Speed Planes"....or something like that.
Although I have accepted electric speed enthusiasts into the Revver's I think that the
discussion of electrics may not be to the betterment of the Club.

The fact of the matter is....we have about two hundred glow and nitro Revvers, and a
half dozen electric buffs. Oil and water do not mix. Fact is, nitro guys don't care about
electrics and don't bother to read about them....and likewise, EP fliers couldn't care
less about the nitro/piston birds.

So....let's get a speed EP thread going, and you guys copy and paste your posts into
that thread, OK ? I will clean up this thread after this is accomplished.

Comments anyone ?

Gryphon

Flyboy Dave,

Either way, no difference to me. As you said; give twinbrother a chance to copy the stuff.


I also have a Nitro Plane. Hanger9 Ultra Stick 120 lite. It has several mods.

Its 120 sized motor came off of the same plane's 60 size version that I wrecked and then salvaged all parts.
I had to cut a hatch just in front of the horizontal stab and stuff the 1100 sized battery there. C.G. was still way off, so added 6 o.z. of lead to the tail.
The old 60 plane with 120 motor on it could go vertical like no other.

Have fun guys,

Gryphon

twinbrother

My Feedback: (7)

Sorry about that. I'll post in another thread.

Razor-RCU

My Feedback: (50)

I always chime in to see who has joined the Revvers Brethren and end up reading discussion posts. Cool posts but they should have their own threads-

Congrats on your watts, amps and KV and 1/2 bladed props. and everything tho-