Anybody know how many amps the firebird motor and stock prop pull - RC Groups
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Dec 02, 2001, 06:36 AM
Barrett's Avatar

Anybody know how many amps the firebird motor and stock prop pull

I want to build a small plane out of all the scrap bits of stuff that i have laying aound the garage and i want to put a firebird motor in it. Ill be using the stock four cell batt and grey prop, but all i have is a 5 amp ESC. Is this enough. My thinking is that it wil be enough because it is a very thin prop and i remembr the flight times of my firebird being very long with the 600mah batt. So im guessing that the amp draw wasnt to high. Thanks.
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Dec 03, 2001, 10:44 PM
Registered User
MrThermal's Avatar
Yea, I think a 5A ESC is plenty for the Firechicken motor w/4cell bats. Some of the guys
here are running 5 cells w/speed wing & getting good results. My modified XL swings a zagi
125x110 and gets 20-27 minute flights w/stock bats. (but does use my custom, scratch built wing)
Why not use a S400 ?
Dec 03, 2001, 11:18 PM
Barrett's Avatar
Mr thermal, do you mean why dont i use a s400 with the 4 cell batt and 5A ESC? I wouldnt think that would be a great combo.
Seems that the s400 would be better off with more cells, which in turn would pull more amps, and then my ESC wouldnt work. And besides ive got a Zagi with a s400 and i want to try somthing a little different.
My firebird has been out of the air for a while because of a broken tail boom and ive got some micro servos and a micro rx, so i figured that i would just try and copy the basic firebird size and shape. I plan on using foamboard for the pod, a carbon arrow shaft for the tail boom, and corroplast for the tail. For the wing I was jst going to use the original firebird wing, or shape one out of foambord with a heat gun. What do you use to build you wing? Thanks for the response.
Dec 04, 2001, 08:46 AM
Rehab is for quitters
LuckyArmpit's Avatar
I don't know about the regular firebird but the firebird xl uses a
6 cell 900 mah nimh pack. Motor is a Mabuchi 380 and I think is
7.2 volt. I'm guessing the prop is 7x3 or something to that effect.
AUW of the xl is roughly 16 oz. Barret, I'd try to use a foam tail group instead of coro to keep weight down.

Dec 04, 2001, 11:29 AM
Barrett's Avatar
Hey there Lucky, Ive got the first firebird or the regular one. It uses a 4 cell nimh 600mah. And i think the motor is a 200, or at least that what the box said. Last night i was thinking about how much it would weigh, and you are right, i should use foam for the tail to shave off some weight. The reason i was thinking of useing corro is because it hinges so easy, and its tuff. But, ill just hinge the foam with tape. Im going to start soon on the pod, ill try and post some pics if i can just for fun. I dont have a digital camera or a scanner, but ill think of somthing.
Dec 04, 2001, 05:46 PM
Registered User
MrThermal's Avatar
Check out the foamie forum and do a search for
"meat tray foamies" All info. U need for tail
feathers. Are U planning on V-tail....or
preferably rudder/elevator ? My buddy has fixed
his broken tailboom more than once w/epoxy...
and still flies. My XL wing used convential
rib/spar construction w/balsa & spruce and covered
w/monocote. Sorry, my idea about the S400 won't
work w/your 5A ESC. Please go the rudder/elevator
path so you can do loops and give it some UP or
DOWN instead of using motor power. You will have
to install pushrods and get rid of the fishline.
Dec 04, 2001, 06:05 PM
Rehab is for quitters
LuckyArmpit's Avatar
Barret, I was sorta thinking of making a firebird xl II. Only, rudder/elevator and on a speed 400. For your idea, probably
a 10 to 15 amp esc will do. Also agree with MrThermal, definetly
use pushrods. You can get by with HS-55's or HS-50's for servos.
They are light enough and will be able to handle moving the surfaces. Post a pic when you can.

Dec 04, 2001, 06:27 PM
Registered User
Originally posted by MrThermal
Please go the rudder/elevator
path so you can do loops and give it some UP or
DOWN instead of using motor power.
A V-tail can do that, you just need to use a mixer.
Dec 04, 2001, 09:23 PM
Barrett's Avatar
Yea im going to go with the rudder/elevator setup, mainly because this seems a little easier to attach to the tail boom. There are two reasons that i want to build this plane. One is just because i want a small plane that should only take a night or to build, and the second is im hoping that it will be easy enough to fly that my dad will be able to handle it. I went to his house during the holidays and i brought along my mini zagi. He really seemed to enjoy watching it fly, but its quite a handful to control.
Next time i visit Id like to have my Firebird copy and hand him the sticks for a successful flight.

Ive got two problems though. I cant find foamboard thin enough. I went to four stores tonight lokking for at least 1/8 foamboard. The only thing that any of the stores had was 3/16. To me this is way to thick for the motor that i plan to use. Tommorrow im going to go to a grocery store and see if i can get any meat trays. Any others ideas guys? The second problem is the ESC that i thought was a 5A is really a 2A. So i am ordering a new one from castle creations.
I was thinking of getting the pixie-7p. Seems like a good one. 3-8 cells and 7A continuous with a 10A max rating. The ESC that i was going to use was the one from the GWS flight pack that i got wth my Tiger Moth. Its been a while since i pulled the bottom wing of to look at the electronics, so i had forgotten that it was only a 2A ESC. Oh well now iv got an excuse to get a new one.
Dec 04, 2001, 11:22 PM
Registered User
<b>You recently replied that "a v-tail can do that..
just use a mixer".....well dude have you ever
seen a firebird with the fishline pull setup ??
no way it would work without regular pushrods
AND if your that good @ posting a quote from
someone else........ POST THIS
Whoa whoa whoa! Calm down noobie. There's a wonderful little e-mail I just received from Mr. Thermal. Chill out man, we're all (well, almost ) friends here.

And yes I have seen them. I work part-time in a hobby store and have given class to some of the people who bought them. Again, yes, it will work without pushrods. You could use either a pull/pull config to save weight or modify the rubber-band and fishing line tail to be able to move down. You would just need to flex the hinge the other way a few times or cut it and hinge it with tape. Use the rubberbands just as they are. Connect the fishing line to micro servo control horns and there you go. Problem solved.

Edit: fixed spelling
Last edited by VWtechie; Dec 04, 2001 at 11:31 PM.
Dec 04, 2001, 11:34 PM
Barrett's Avatar
Whoa there guys! Just remember also, that my plane wont be a firebird, it will just kind of look like one. Hopefully the tail on my version will be a little more responsive than the tail on the firebird.
That was one of the things that i didnt like about my firebird, it seemed to need a big area to turn in. And besides no v-tail for me. He He.

And yes, we are all friends.
Dec 04, 2001, 11:42 PM
Registered User
MrThermal's Avatar
How do you plan on using a pull/pull system and mixing with the ONE servo in the firechicken ??
It's my understanding that you need TWO seervos to mix.
This response I got to see
Dec 04, 2001, 11:47 PM
Registered User
I never said anything about using a single servo. In order to use a mixer you must have at least two servos to "mix." Since he's not using the FireBird's electronics he doesn't have that limitation.
Dec 04, 2001, 11:56 PM
Barrett's Avatar
I dont mean to post in VWtechies place, but i think he was just reffering to any plane with a v-tai. Ive seen some v-tails do some cools loops and rolls. Also I think VWtechie understood that I plan on useing two servos. I considered a v-tail because i believe it has less drag than a rudder/elevator setup, but it will be just a tiny bit harder to attach to the tail boom of my design, so i decided against it.

Seems that VWtechie noticed that you had a small amount of post and thought that you may not know that a v-tail was capable of aerobatics. I think he was jst trying to help. But i could be wrong. It wouldnt be the first time and and it wont be the last!
Dec 05, 2001, 12:12 AM
Registered User
Thank you Barrett. I was just trying to explain that it isn't very difficult to modify a FireBird style V-tail to give full rudder/elevator type control, and since it's lighter and has less LE area it is more efficient. An inverted V-tail is really the best way to go but I won't try to push it any farther.