• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.

Planning an FT Spear build!

JennyC6

Well-known member
#21
I'm planning on getting MOST of Flite Test's speed builds. Have to get s bunch of dental work done for the wife first. By the end of the year i plan on having fpv equipment and a room full of planes!!
Pop one of these engines on one, then! Hehe.


I, too, plan on doing most of the speedbuilds, but the majority of them...if not all of them...will be glow powered. The larger ones will likely get OS mills, the Mighty Minis will run on Cox power.
 

FastCrash45

Well-known member
#22
Pop one of these engines on one, then! Hehe.


I, too, plan on doing most of the speedbuilds, but the majority of them...if not all of them...will be glow powered. The larger ones will likely get OS mills, the Mighty Minis will run on Cox power.
I just jeep adding to my wishlist of things I want now. Now it's a throttled. 049!!! I'm gonna be broke until the end of time. I'll be having fun though.
 

JennyC6

Well-known member
#29
@FastCrash45 I did it for less than the cost of one engine, a fuel tank, and related support gear. Amazon's got some good stuff for nothing. Let's see here...

https://www.amazon.com/gp/product/B011915FCG/?tag=lstir-20

https://www.amazon.com/gp/product/B01N48QUIP/?tag=lstir-20

https://www.amazon.com/gp/product/B01H36AIGY/?tag=lstir-20

I would suggest getting a bit more bank involved and picking up a set of EV-800d goggles, though. That VTx has a mic and transmits audio, but that receiver won't play it back into the TV for some reason.
 
Last edited:

FastCrash45

Well-known member
#34
Nope! The toys used may change, though.

That truck's got a 540 sized 5,700kV Castle Creations 4-pole in the nose. She pulls hard. Almost makes me want to try to use one in a plane...
I've been thinking the same darn thing about my 5200kv. They would swing some large props in a hefty plane!!😁
 

JennyC6

Well-known member
#35
I've been thinking the same darn thing about my 5200kv. They would swing some large props in a hefty plane!!😁
Bet if you geared it 10:1 and threw 3S on it you could swing a 16" prop and hit 120MPH.


The biggest issue, I think, with using a car e-motor in a plane is RPM. They're designed to turn ludicrously fast on barely any voltage. On 2S the motor in my CA-10 or your 5200kV would turn more RPM than the typical C-pack motor does on 4s. But if you could get the RPM issue sorted out you could probably wingrip a foamboard warbird in level flight with one. Especially on 3s.
 

FastCrash45

Well-known member
#36
Bet if you geared it 10:1 and threw 3S on it you could swing a 16" prop and hit 120MPH.


The biggest issue, I think, with using a car e-motor in a plane is RPM. They're designed to turn ludicrously fast on barely any voltage. On 2S the motor in my CA-10 or your 5200kV would turn more RPM than the typical C-pack motor does on 4s. But if you could get the RPM issue sorted out you could probably wingrip a foamboard warbird in level flight with one. Especially on 3s.
Probably have to use a gas prop too. I wouldn't trust the smaller hubs on electric props considering the torque and speeds they would reach. Might have to consider my 2600kv motor first. Keep the rpms more reasonable. It's gonna have to be a sizeable plane so it won't flip over if ya dump the throttle. Like a 12x8 on a 50in + bird. Fun to ponder the possibilities!!
 
#37
this is what i like to see, more glow aircraft! I'm not sure if anyone has mentioned it yet but because youre engines are in a pusher configuration, you will need a brass washer between the crankcase and thrust washer to prevent the thrust washer from eating into the crankcase over time. I put a Babe Bee on a sword wing and just after one flight there was a notable gap between the thrust washer and crankcase, which is why I only run tractor configuration on all of my cox stuff now. I admittedly only skimmed these posts so it may have been mentioned already but cox engines love 30% fuel and 6x4 props. not only will this combination give you more power but it will also make it easier to tune. as for starting them for counter rotating, ive found that most of my engines will start opposite the flip, so if you flip the prop clockwise, it will start counter-clockwise or visa versa.

see this post for a build of my own: https://forum.flitetest.com/index.php?threads/ft-mini-scout-on-nitro.31556/
 

JennyC6

Well-known member
#38
this is what i like to see, more glow aircraft!
(y)

Keep a close eye on me, then, because I have a very strict rule for my RC hangar: If it's practical to use ICE, it gets ICE. And that means pretty much any prop plane gets an engine. I run glow on the ground, too~!

I'm planning on seeing just how many FT speedbuild kits I can slap an engine on. It's looking like the only ones that'll give me any grief'll be the EDF jets and the F22. The Mighty Minis should fly nicely on reedy 0.049s(And if I wanna get splurgehappy I can get an RC TeeDee 0.051 that chucks out a little more than 2x the power of a 'Bee' style reed valve engine!) and the larger birds'll likely get a mixture of OS 10LA and 46AX power. 10LA will likely be on the more docile planes(IE the Simple Storch, Cruiser, Founders Plane, that sort of bird), while things like the warbirds, the Kraken, will get 46AX power.

The larger birds will be easier to protect from the exhaust schmoo, but the smaller birds are more affordable to power(Engine+Fuel Tank is about 60 bucks shipped for a Mighty Mini), so I'll probably be building the minis first.

Might also experiment a bit. Cox Intl sells the Tee Dee carbs seperate, I might try to graft that onto a spare choke tube to replace their choke style throttle for even better throttling. And I might just save up for a Tee Dee RC, just to see how fast I can run a Mighty Mini of some sort on glow power(Prolly be the mini Arrow, flying wings tend to be super sleek).
I'm not sure if anyone has mentioned it yet but because youre engines are in a pusher configuration, you will need a brass washer between the crankcase and thrust washer to prevent the thrust washer from eating into the crankcase over time. I put a Babe Bee on a sword wing and just after one flight there was a notable gap between the thrust washer and crankcase, which is why I only run tractor configuration on all of my cox stuff now.
I haven't seen any of that wear on mine yet. I am aware of it and I'm keeping an eye on it, however, and I have the tools to properly remove and install the crankshafts.

I might make a whole ordeal out of it and also swap the crankcases out for some really cool looking scratch'n'dents on Cox Intl's website that ended up looking rusty because of failed anodization, swap the cranks out for heavy duty diesel/Killer Bee cranks, and throw brass drive washers on it. I might also see about getting the exhaust ports opened up a bit; my engines have the dual-slit safety ports and removing that center bar would help them breathe a bit better.
I did know that this is why you never ever use an e-starter on one of these engines. In my experience you don't really need it, if the engine doesn't light off within a few flips something isn't right and needs addressed.
As an aside, I've been quite impressed with the reliability of them. I've always read that these little engines were cantankerous little -beep-s, but mine have more or less been model citizens, only acting up when the fuel system didn't cooperate. Maybe Cox Intl has changed the formula slightly in making their current production 'Bee' engines? Maybe having the throttle on the choke tube forces them to run a little better? I do run high nitro high castor fuel, which they like, and that may also be part of it.
I admittedly only skimmed these posts so it may have been mentioned already but cox engines love 30% fuel and 6x4 props. not only will this combination give you more power but it will also make it easier to tune.
I've got Fitz Fuels Rocket 24 going through them and they seem to love it. They're propped with 5x3 three-blades, and that's as big as I can get on this bird. The tip clearance is about 1/4 of an inch! And to get even that to work I had to cut some sizeable notches in the wings/elevons for clearance. I can add more blades, though, in fact I have a smattering of 5x4x3 and 5x4x4 drone props sitting here that I might try on bench runs of a third engine to test for fatiguing. I figure if they can survive drone crashes they can survive use on a reed valve 0.049, but just to be sure and certain I'll run a quart or so through one on the bench and check for fatigue cracking near the hub while there's a scatter shield around the prop in case it does fail.
On planes with more clearance I'll probably be using 6x4 or even 7x3 props. I hear tell a reedy will swing an 8x4 at about 11,500 or so but if I'm trying to swing a prop that large I might as well jump up in displacement to an OS 10LA.
I have to wonder how much power my engines are producing. I'm running 3-fin glow heads, 24% nitro (20%oil consisting of 18% Klotz castor 2% Klotz synthetic), and the engines are basically fresh out of break-in. I've read that they put out about 40-45 watts at the prop, but those figures are also quoted on 15% nitro.
as for starting them for counter rotating, ive found that most of my engines will start opposite the flip, so if you flip the prop clockwise, it will start counter-clockwise or visa versa.
I have spring starters on my engines so they can't run in the incorrect direction. They try every start, usually I'll get nothing, spits of fuel, a pop, pop'n'snort, oscillating for 2-4 seconds, then on the next flip they kick on over in the correct direction.
see this post for a build of my own:
Oh wow, you only used a 0.020. I'm planning on using another throttled 0.049 on a Mini Sportster and then a Mini Scout! It's nice to see that a Pee Wee was able to fly the Scout comfortably, makes me happy that I'll get acceptable performance on a throttled Sure Start 0.049 swinging a 6x4x2 prop on the Mini Sportster and Mini Scout.
I say you give it another shot. A layer of Rustoleum paint seals the foamboard nicely(My Spear is having ZERO de-lam issues near the engines and fuel tank), so you can actually have one last more than a couple flights, and Cox Intl sells brand new throttleable Sure Starts for 44.99. Killer deal if you ask me. And that same outfit sells all the support tools, spare parts to keep their repro engines and original engines alike buzzing along happily.
Oh, hey, you know of a typical service interval for the piston/rod ball socket? I have the reset tool but I don't know how often I should pull my engines down and use it. So far mine aren't showing any symptoms of a piston that doesn't move properly, so I'm figuring they don't need it right now, but I have no clue how long they go between resets.
I do anticipate longer intervals than normal since mine are throttled and won't be running at wide open throttle every second they're running. That'll mean less stress on the piston/rod socket, less RPM, less wear.
 

JennyC6

Well-known member
#39



FPV system in action! OSD layout:

Top left ----------------------------------------------------------- top right
Name---pitch indicator---roll indicator---FPV supply voltage

crosshair
Artificial Horizon
Compass
Home Dir/numerical Heading
Barometric Altitude----G Meter-----------------------Warnings
bottom left ------------------------------------------------ bottom right​
 
Last edited: