Flite Test Commuter w/ RC Ranger engine!

micro 0951 wrote:Nice work! But wowzer, 4oz? I'd say 1 or 2oz would be more fitting for a FT commuter. I get 30mins of engine run time on my Q-Tee, with a 2oz tank. A 4oz could, in theory, give you 45-60mins, depending on fuel consumption.

that was the whole idea. This isn't the type of plane you do 3D with, or zoom around with, or anything like that. This is a cruiser. And I figured 'hey let's see how much fuel I can jam pack into the thing!'. Turns out a 4oz tank is literally about all the room it has; I had to relocate the elevator and rudder servos to new spots halfway down the tail because the back end of the fuel tank is where they're intended to be.

On the plus side, the tank did fit, and the tank's center is more or less right on the recommended CG, so I shouldn't have too much issue with fuel burn-off upsetting the thing.

My first few flights will likely be on a quarter tank, maybe 1/3 tank, as I need to make sure she's gonna A: fly nice on low fuel(The CG is about perfect with an empty tank!) and B: last thing I need on a maiden flight is a plane that's testing the limits of its capability to lift things. Especially since I, myself, am still incredibly new to this. I did get some stick time in on my NexSTAR last saturday, though! Popped down to a local-ish field, another pilot took it off, trimmed it, passed my radio to me, I flew it a bit, passed back to him, he landed it. NexSTAR's maiden, too. Go figure.

If you want to see more details on the build of the Commuter I documented most of my modifications on the FT forums here

The bigger concern is weight, the commuter is a small plane, designed for mini quad components. The ranger engine weighs as much as the recommended motor, esc, and battery combined.

Another reason I moved the tail feather servos. The thing was so nose-heavy during construction the balance point was pretty much right on the firewall until it was fully assembled.

Factor in the fuel tank, fuel, receiver battery, throttle servo, etc, and the weight adds up rather quickly. I suspect with a full 4oz tank she'll still fly, although the wing loading may be so high the commuter would end up flying like a warbird/pylon racer (FT mini mustang or mini corsair).

I posted it on the FT Fans facebook and none other than Ben Harber himself commented on it! He was wow'd by it, said he couldn't wait to see it fly, and then he and I chatted a bit about it. He had 80+ gram 4K action cams strapped to the thing's back and it flew fine; he said it was thrust limited not wing limited, recommended a 6" prop. I told him I had a 5x3 3-blade on it now; apparently he was only using a 2-blade. Another thing to keep in mind is I don't have the additional drag of the cameras, so while I do have more weight, it's all held internal to the plane.

He thinks itt'l fly with the weight. My biggest concern with this build has always been weight and Ben himself telling me the thing carries action cams like nothing is a bit of a relief.

I do fully expect it to be very very scale in take-off and climb-out when it's fully fueled, and that the engine's going to be screaming the whole time. But hey, these engines didn't originally have throttles at all, so that'll be fine!

However she turns out, keep on experimenting! The great thing about the cox 049s is that they just fit into pretty much every parkflyer sized foamie, the possibilities for electric -> glow conversions are endless!

I've set a goal for myself: Nitro power as many FT Speedbuild Kits as I possibly can. And that means a LOT of   powered foamies in the future.

getback wrote:That looks like foam under a paper bag covering ? If the foam is not fuel proof ur going to have some disinaration going on from the fuel the fuel will be everywhere and covering will get soaked (not good)

Valid concern. And that's why I'm using an FT Speedbuild Kit. Whatever Flite Test did with Adams Readi-Board to get their foamboard waterproofed for floatplane usage also makes it fairly resilient to glow fuel. A sizeable raw fuel spill will delaminate the paper, but that's about it. Castor schmoo barely fazes it, the foam itself really does not care about fuel presence.

Rustoleum paint works well to protect the foamboard(P.much impervious to fuel spills when so painted!), which when combined with sealing the edges, makes it no less long lived than a balsa plane would be.

And a surestart engine with a carb. but how did you get the needle in one place and the carb. in another / they are inline originally. ** Not trying to pop your bubble but more concern than anything . **

The choketube and throttle are seperate parts from the mixer, so I just made some slight modifications to the backplate and rotated the choke tube 90 degrees. The mixture needle in the RC Ranger engine is in the backplate itself. It's not a true carb, per se, but it does throttle them reasonably well as long as you remember to clear their throats every minute or two if you're running at low power.

https://coxengines.ca/throttle-conversion-for-cox-049-engine.html

getback wrote:Got you !! as long as ur safe and feel good with it , Thats Cool !! Never worked with foam but a few here have and i listened in LOL Hope you can give us a flight report ,Love to see her in action . That's pretty good stuff with the dragon bee change in the add on ? to get u some ideal and Rs too .

Planning on getting some video of it actually. First couple flights on a light fuel load, probably 1/3 to 1/2 of a tank at most, before trying it out on a full tank.

What is the total weight of the plane?

Got the first layer of paint on!

Surfer_kris wrote:What is the total weight of the plane?

No clue. I don't have a scale that's accurate that low.

You will want use a scale to see what things actually weight and where you can save weight. A simple kitchen scale is often enough.

Surfer_kris wrote:You will want use a scale to see what things actually weight and where you can save weight. A simple kitchen scale is often enough.

Yeah I need one. not a kitchen scale, though. I want one that has hooks on both ends, which will also let me directly measure thrust.


That being said, I chatted up Ben Harber himself, guy who designed the thing. And he reckons itt'l fly with the right prop. He said he was carrying 80+ gram action cams on its back and it was thrust limited, rather than wing limited, and I don't have the added drag of a big ol' 4k action camera hangin' out in the breeze.

The project looks like a way early stealth technology to me. Can't wait to see how it all works out. Thanks for thinking outside the bag!!?? Way Cool !!!! Mark

Reminds me of a slot car I built at age 12. Monogram brass chassis with lg. can Mabuchi and a body I made out of shirt cardboard to look like the Beverly Hillbillys jalopy.

JennyC6 wrote:
That being said, I chatted up Ben Harber himself, guy who designed the thing. And he reckons itt'l fly with the right prop.

You'll need to know the total weight of your plane and the total plane of his plane, in order say anything about how they will fly.

And yes, the three-blade prop is likely too much load for the engine and it will not deliver optimum thrust. A two-blade 5x3 prop, or the APC 5.7x3 prop, will be better suited to the engine.

Thinking outside the bag??

https://www.youtube.com/watch?v=rnDEr9R0snU

Surfer_kris wrote:

JennyC6 wrote:
That being said, I chatted up Ben Harber himself, guy who designed the thing. And he reckons itt'l fly with the right prop.

And yes, the three-blade prop is likely too much load for the engine and it will not deliver optimum thrust. A two-blade 5x3 prop, or the APC 5.7x3 prop, will be better suited to the engine.

Calcs say I'm getting half a pound of thrust off of this prop and getting about 50 watts out of the engine, which is right in line with what a basic reedie will do. I'm not expecting to have sky-ripping speed or unlimited vertical but I do expect enough thrust to get off the ground and maintain altitude without much fuss. And I can always put a hotter cylinder on it if I want to.

What rpms are you getting?

You'll typically need about half of the airplane's weight in terms of thrust, in order to have a comfortable level flight.

Surfer_kris wrote:What rpms are you getting?

You'll typically need about half of the airplane's weight in terms of thrust, in order to have a comfortable level flight.

Real Cessna 150 only has ~320lbs of thrust, weighs 1600, flies fine. My model's going to have a way better thrust/weight ratio than the prototype could ever dream of having. My best estimate put it at somwhere between 10 and 14oz all up, depending on fuel load, which puts it right near your estimate.


I'm not overly concerned about it. Itt'l fly. And if it's excessively underpowered I'll slap a Tee Dee cylinder/glow head on the engine and fit it with a 6x4x2 Top Flite wood prop, of which I have a literal fistful.

Are thinking about making a video of maiden flight?

ticomareado wrote:Are thinking about making a video of maiden flight?    

If I can find a way to keep it in frame, yes.

JennyC6 wrote:
Real Cessna 150 only has ~320lbs of thrust, weighs 1600, flies fine. My model's going to have a way better thrust/weight ratio than the prototype could ever dream of having.

You'll need to think about the scaling, the relative drag is different when you go from full-scale to RC scale.

Here is a little guide that illustrates how the weight and engine size will affect the handling of our RC planes, and it also includes a comparison to full-scale planes:

How do I calculate the wing cube loading given the weight and wing surface?

Also, it's hot and my brain is melting trying to convert to imperial, need to find a metric version of this chart.

You can use online "calculators", like this one: http://www.ef-uk.net/data/wcl.htm

Conveniently the WCL number itself is actually the same in both unit systems (!)

Here is a metric version that I have "converted" from the earlier graph, it is in swedish but hopefully you can identify the circles from the previous figure:

OK, so I'm somewhere between Sport and Pattern with my D.520, pretty good.
I'm gonna use this for my next models, thanks.

IT FLIES! IT FLIES!

Maiden flight of an overweight, underpowered, nitro powered foamboard plane that was also the pilot's first solo fixed wing RC flight and second ever fixed wing flight. And it flew! Took off easy, any herki-jerkiness of the flight is all down to my inexperience, nerves, excitement.

I did have to re-prop it, though. I tried it with the 5x3x3 and it got about 2-3 inches off the ground. That was it. Just didn't have the airspeed. Swapped to a 6x4x2 wood prop and that was the magic bullet. Up it went and it didn't even care about all the extra weight it was carrying....so long as it was on power.

I did have a dead-stick crash landing though. The throttle servo came un-glued mid flight, which meant the engine was randomly going from full blast to about 1/3 power. This wasn't too much of a problem as long as it stayed running...mostly only changed the noise it made...but it loaded up and flamed out on me. All I could do was aim it for the 6-inch tall grass and hope for the best, 'cause when it fell silent it fell like a cinderblock!

Damage report: Nose gear ripped off, throttle servo unglued. That's it. She'll fly again next week, on a full 4-ounce fuel load! And hopefully I'll have better video; gonna try to get one of the other guys there to record it for me rather than rely on my phone being mounted to my transmitter with one of those phone spiders. Works okay for cars, not so much planes.

Oh, and the Cherry Red paint makes it so so so so so so so so easy to see in the sky. Lovin' it!