View Full Version : Need help with a Cox Micro P-40

04-03-2006, 03:23 AM
Can anyone tell me if I can use a Hitec Focus SS 2AM radio with a Cox Micro P-40? I would like to put an inexpensive system in this bird but one that will be reliable. I see you can pick up some used transmitters and receivers for under $40. I would assume then I need to buy a speed controller and two micro servos. The Hitec receiver comes with a battery pack that holds 4 AAAs but that looks to me like it would be to bulky and heavy for this plane. The plane is still new in the box so I can go any direction with it.

I'm open to suggestions on any other sytems also.



Sky Sharkster
04-03-2006, 04:14 AM
Hi Tom, there's a long thread on these planes, page 3 of this Forum, "Anyone seen the new Cox Warbirds?" Posted by K5083. It's several pages long, page three (of the thread) has a half-dozen suggestions on servos, RX's, and other modifications. Pages 4 and 5 have flight results.
Most flyers seem to be using the sub-sub micro servos, less than 5 grams each. The HS-50's are about this weight, also Cirrus makes a sub-sub micro about 4 grams.
You could use the Focus TX but the RX will need to be really small and light, not just to save weight (although that's important) but also size, there's just not much room inside. FMA Direct has a very small, light FM RX for about $30.00 plus crystal.
I've seen several of these little birds fly, they are a blast to watch! They fly pretty well but only in calm weather. Also, as you might expect, weight is a major factor, a few grams more or less makes a big difference.
The ones I saw had replacement Feigo B/L motors, direct drive, 2 cell LiPo and most had the servos mounted flush on the surface of the fuselage, right behind the wing. They ripped around in an amazingly fast pylon-type race for awhile, then they broke off into a dogfight. What a hoot!
It's not as easy as it might seem to get them flying well, but from what I've seem, it's worth it!

04-03-2006, 04:31 AM
Thanks Ron,

I'll jump over and read the thread. This is just another plane in the closet that hasn't been touched yet. Not that I needed it, but I saw it new for $17 and couldn't resist. Unfortunately, the plane is the cheapest part of the set up. Do you think the new Spektrum DX6 receiver would fit in it? I'm looking at that system for my E-Flight P-47 that you helped me out with last night. Would it be easier to by an extra receiver so I can use the same radio for both, or will that even work? If it does, can you run third party micro servos and speed controller off the Spektrum receiver?


Sky Sharkster
04-03-2006, 01:24 PM
Hi Tom, about the Spektrum, The RX is dedicated to the radio system so if you want to fly other planes with that radio system you'll need to buy only their RX's. Then you can fly using the same TX. Other brand servos and ESC's will work OK. As far as a RX just for that plane, it really depends on two things; Do you want to spend the money, and is it an easy (or even possible) change-out? In other words, if you only have 1 RX for two planes, can you swap easily?
Most flyers (myself included) have more aircraft than RX's. Before I go flying I figure out what planes I want to fly and those planes get the electronics. As I build new planes I "steal" RX's and servos from the ones I don't fly as much. I don't swap RXs at the field, that seems like asking for trouble.
Typically we're flying $75.00 aircraft with $200.00 worth of electronics inside. As you get into brushless motors and ESCs, the numbers go up. Not as much as they did a couple of years ago, but still, up. LiPos vs NiMh, same thing, but you can easily use batteries in more than one plane. Electronics like RXs and servos, not so easy.
If you plan to fly "Park" flyers and small models the Spektrum is a good choice. I also fly E-Powered gliders so the limited range is a major issue. Until they release a system that is comparable to the best dual-conversion FM (in range) I'll stick with my MultiPlex TX and FMA Direct RXs for gliders and powered gliders. I've read reports of flyers "specing" out 2 meter gliders with the Spektrum system but haven't seen it myself.
Good luck with the "Micro", you'll have a lot of fun!

04-03-2006, 03:39 PM
Hi Ron,

First I would like to say thatnks!! You are always a huge help.
I was actually thinking about buying an extra Spektrum receiver for the Micro P-40. I think they run around $59. As it stands right now, I have 4 planes, a PZ J3 Cub, a PZ P-51 an E-Flight P-47 and a Cox Micro P-40. The only radios I have are the PZs which as you know are dedicated systems. The reason I am looking at the Spektrum is because I do fly in a lot of parks and school yards and don't want to worry about getting radio interference and even worse, me shooting someone else down that might be flying nearby that I'm not aware of. It looked to me like it would be about as inexpensive to put the new Spektrum system in the P-47 and buy an additional receiver for the P-40. I would not plan on swapping receivers out of the P-40 since it's not easily done. After reading the thread you pointed me to on the Micros, there is a lot of good info there on components and should be pretty easy to select an ESC, servos and battery.

Right now, I think the P-51 and P-47 are about as large as I will get, but who knows what the future will bring. It will be my luck that someone will come out with a great looking larger ME 109 and since I'm a sucker for warbirds, I know what will happen. If I don't use the Spektrum in the P-40, then I will need to buy another radio besides the Spektrum or get away from the Spektrum altogether and go to a regular system that can easily mix and match receivers.

Right now, I'm just trying to figure out which systems will give me some flexibility and not drain the wallet.


Sky Sharkster
04-03-2006, 04:32 PM
Hi Tom, thanks for the kind words! I try to help if I can. Regarding the radio choices, the Asian brands (JR, Hitec, Futaba + Airtronics) and Multiplex (German-made) offer the most flexability since you can use any after-market RX and servos, Gyros, etc. Spektrum system has 2 limitations, the overall signal range and RX options (none). If you can live with those limits, the Spektrum is likely a better choice since it is more interference-resistant within it's signal range and there's no channel conflict with other flyers.
I may have been misleading when I said the Spektrum was for small models. What I meant was that the advertised range isn't far enough for gliders and other large models to be flown more than 1000 feet away. At least that's the figure Horizon Hobby had posted last month. You could easily fly "Speed 400" sized models and most non-gliders, since the radio range wouldn't be the limiting factor, visibility would.
So if you don't mind the RX non-options and aren't going to fly 2-meter (or larger) gliders, the Spektrum is a great choice. Also, this is just their first offering: I believe they will improve the line as they go along, maybe a less-expensive 4 channel RX and maybe (hopefully) a greater transmission range.

04-03-2006, 04:53 PM

Guess the first thing I should do is learn how to spell. I see I misspelled "Thanks" in the previous thread. Maybe we could get spell check added for people like me that are spelling challenged? I understood what you meant when you said the Spektrum is for park flyers and it was more of a range issue rather than component size. Since I'm new to all this electric stuff, what is an average receiver cost if you were to use the non Spektrum transmitters? If understand it, other than range, the limiting factor on the Spektrum is the receiver. I would still be able to use third party ESCs and servos correct? I don't forsee ever getting into gliders or really big planes so I think I would be OK.

Thanks again,


Sky Sharkster
04-03-2006, 05:52 PM
Hi Tom, on the RX's, until recently, most 4 channel full-range FM (72Mhz) receivers were about the same price as the Spektrum offering, $60-$70. Within the last year or so there's been two "major company' offerings of 4-channel "sub" micro RX's, Castle Creations, one of the most highly respected makers of ESC's, now carries the Berg RXs, the MS4 is about $40.00 and FMADirect now has the M5v2 sub micro for $40.00. Both require a crystal, but you would need a crystal no matter how much you paid for the RX (except the Spektrum, no crystal required). There are also RX's in the $20.00 range from Blue Bird + GWS. Those are available from
Berg- http://www.castlecreations.com/products/berg_ms4.html
FMA- http://www.fmadirect.com/detail.htm?item=2098&section=1
I guess when you look at the total price of a $40.00 Rx plus crystal it's not that much less than a $60.00 Spektrum. I don't know how small the Spektrum RX is, the Berg + FMA are tiny.
The Spektrum RX will accept all standard servos, ESCs and other components like gyros, "Y" conectors, etc.
Hope this helps!

04-03-2006, 05:59 PM
Wow! I think I'm actually starting to understand this new addiction of mine. Now if I can just control it.

Thanks for all your help Ron!

04-03-2006, 09:57 PM

Just for your info, here's the specs on the Spektrum receiver.


Size: 39mm x 30mm x 9mm (1.53" x 1.18" x x.35")
Weight: 7 grams (.27 oz)
Voltage Range: 3.2-9.6V
Current: 75mA
Antenna Length: 95mm (3.75")
Antenna Orientation: 90 degrees

Sky Sharkster
04-04-2006, 02:15 AM
Hello Tom, thanks for the info on the RX, it's just about the same dimensions as the two I mentioned and lighter than the Berg. Should work fine in a "Micro"!
Good Luck

05-04-2006, 03:53 AM
Hi Tom Hi Ron
Just to give you some info Iam running a new berg reciver (36.00 with crystal from http://www.allerc.com) blue arrow 4.3 servos stock motor kokcam 2 cell 340 mah batt all up weight 4.3 oz Flys great.The big thing is to prebalance before gluing the sides together.

05-04-2006, 04:27 AM
Thanks George,

Mine is still in the box in the closet. I'm trying to finish up my E-Flight P-47 this week. I think when I get to my Micro P-40, I may have to spring for another Spektrum receiver so I can fly it on my DX-6. I'll copy your post so I have a reference of the servos and battery. Are you using the stock motor? How does it handle wind?

05-04-2006, 01:00 PM
The stock motor works fine.I take off on full power,then back off to half.It does really good in the 2-4 mph winds just wath out for the ground effect wind on landings.Its nice that cox is above sea level.If it flys nice up here,you guys that are lower it should fly great