Invertedflyby

My Feedback: (15)

I wish they would stop building all of these planes and advertising them here so I’d quit buying them. This is the third one I’ve converted to glow. I was looking for a quick build for a Pee Wee and was about to buy an EarlyRC kit but saw this L-4 and it looked like a challenge.

The plane looks great and is really well built, all of the control surfaces were hinged and it came out of the box with the tail on it. All of the work was putting the servos in and the glow conversion. The engine mounted perfectly to the firewall inverted and still fit in the cowl.

The hard part was the tank. I wanted more than 2 minutes of runtime so I used a backplate with separate tank. I couldn’t find a tank to fit in the space so I soldered one out of .005” brass about 7/8” square. Then I cut and glued some square balsa pieces in to seal the firewall and fuelproofed it with aerogloss.

I didn’t know if it would be possible to run a completely cowled PeeWee but I was able to fuel it and get it started with the cowl on it using fuel line extensions and a remote glow setup. It has a 6x3 prop and 4 head shims. I was hoping to do touch and goes with it but it seems like all low throttle does it make it quiet, it still wants to roll pretty good. Has anyone run completely cowled in Cox engines? Done touch and goes with exhaust throttle Pee Wees?

I don’t know if it will fly, it weighs 11 ozs… but it wanted to go pretty good when I let it roll a couple of feet. If it flies it will be very scale like, like a full size cub with an A-65.

Here's a video of it running. http://rcuvideos.com/video/E-Flite-L-4

Will report back when I have a chance to fly it.

combatpigg

My Feedback: (3)

IFB.......you sadistic monster! Look at how you're treating that tiny little engine, it looks like it's bolted to a 1/4 scale plane there.........

I'm guessing it will be able to fly at 11 ozs. My only experience of any kind in this realm was with a Brodak .061 that could only turn a 6x3 at 12,000 rpm. It could barely fly a 14 oz plane with over 300 sq " of wing.

This model looks great, good luck with it!

Mr Cox

Well I have tried an inverted Pee Wee in a scratch built J3 cub. It came out around at around 4 oz and was a little overpowered, it flew more like a clipped wing cub. I was struggling to get it empty a full tank and mounted it horizontal instead. With a dummy on the other side it would look like a boxer engine. Last mod was to put a diesel head on it but I pinched trough the teflon gasket in notime and it now sits on the self...

Touch and goes was a great nono, at least on grass, mine would usually flip onto its back on landing unless I found a short cut patch...

Invertedflyby

My Feedback: (15)

Ha! Yeah it is kind of sick, but I guess it's not that much different than taking a poor airframe that a .020 could fly and putting a hot .049 on it and seeing how tight it will turn around a race course.    

I do wish the plane was just a little bit smaller and it would be perfect.  This has a 38" span 210 square inch wing.  I don't have a tach so I don't know how fast it's turning.  Judging by an old thread on here a Pee Wee with 4 shims and a 6x3 turns about 9k.

That's a cool looking scratch J-3.  4oz!   That is light!  This thing is almost 3 times heavier.  Maybe a bunch of head shims and 0-5% nitro would power yours well since it's overpowered.

Invertedflyby

My Feedback: (15)

Well I put two flights on it today.  The plane flies great but is severely underpowered, which is okay because it makes it a challenge.  Takeoffs take a long time and I'm sure were entertaining because if you get into a groundloop it's impossible to bring it to idle and start over.  You have to be quick on the rudder to stop the ground loop and get another takeoff roll going.  It flies about 10 minutes and will only get to about 100-150ft altitude.  The throttle really is just a volume control, I reduce it to idle once it's up about 20ft and it really quietens down.  I think it would fly better without the weight of the throttle equipment and using a smaller battery pack.

Overall I wouldn't do this conversion again but it will be fun to fly occasionally.

turbo1889

What's the wing span and approx. area? What's the weight minus power plant (engine/tank/throttle-linkage/etc.)?

And the biggest question of all - how much does that brass fuel tank weigh empty ?

Invertedflyby

My Feedback: (15)

The span is 38" and 210 sq inch area.  They advertise 9-10oz flying weight as electric, mine came in at 11oz.   I didn't weigh it without all the stuff before hand and don't want to take it apart now.  But yeah I'm sure being brass and solder the tank wasn't very light but it wasn't as heavy as I thought it would be.  It may do better without all the throttle stuff, 400mah batt and use a regular pee wee tank instead of the brass, and I may try it with 3 shims instead of 4.  I'm using Powermaster sport fuel with 20% nitro and 18% synth/castor mix. 

BMatthews

Severely underpowered by what standard? At 11 oz and 210 squares I'd suggest that you still have a higher power to weight then the original J3. Underpowered? I guess you haven't flown the SAM 1/2A Texaco event then. The plane to engine ratio is at least as bad as this one and then the poor engine is overproped and undernitro'ed until it sounds like it's on idle all the time. The climb is literally an uphill glide..... and very much like a J3 full sized I might add....

Well done on the conversion. The key is to fly it like the L4-A full size was flown.

combatpigg

My Feedback: (3)

I think from this point it would be real interesting to see the plane's performance change after jettisoning the throttle, possibly changing the tank, etc. Just to see what an oz or so does.

turbo1889

My initial reflection on those span and wing area figures is the exact opposite of BMatthews. I'm really surprised that you got a 36" wing span aircraft with approx. 1.45 ft^3 area off the ground in an actual take off not just a hand launch with only 0.020 in^3 displacement engine regardless of how light it was.

I once did a 2-channel "super-mini" sail plane, a self designed TLAR little unit. wing span was more like 40" but it had just about the same area (higher aspect ratio wings). Used a nose mounted Cox 0.020 which was intended to provide a powered initial climb. My total fueled weight came in at just under half a pound (8oz.) - it was built with a super light structure.

It turned out to be a failure - that little 0.020 could keep it flying but didn’t produce any substantial climb rate. Of course I suspect that there may be an altitude difference that contributes significantly to our different results, I'm up in the mountains. I've heard the thicker air down lower is much better both for the engines and the wings. Never tried flying 1/2A down lower though. Heck, I've only seen the ocean twice, once as a kid and once as a grown man. So far haven’t taken any of my planes with me whenever I've made a trip that takes me down lower - next time I end up taking such a trip I should, especially if I end up on the coast again - those big open beaches would make great flying fields.

Invertedflyby

My Feedback: (15)

Of all the R/C planes I've flown this was the most underpowered. I've never flown an L-4 or a cub, but I have flown a loaded 65hp 7AC Champ out of some short strips in the middle of the afternoon in July and August, and as much as I was sweating I felt more comfortable doing that than flying this little thing. (BTW The altitude here is 600', you're right it makes a huge difference being in the mountains.)

The first flight was hilarious because it took off and flew at about 1-2' altitude, it started getting towards the end of the field so I had to do a slow turn out over the grass and it came back towards the runway and landed again right after it got over the concrete. Then it started doing groundloops. I managed to catch it and carry it back to the starting point again, then it took off and I got it to climb up to about 50' before it ran out of gas. The second flight after that one was much better.

I've never seen any Texaco flying but it sounds cool and I think I may since the Pee Weehas become my new favorite engine, starting one with 4 shims is about like starting a rubber band airplane.

I've been thinking a cool contest would be to have a duration event where the only requirement is a PeeWee with a stock fuel tank. The plane could be either FF or RC and any design like a SAM or glider type. These engines are cheap enough if you lost one it wouldn't be the end of the world like aTD. I bought a 4.5' span Hobby Lobby foam glider that weighs about 4.5oz I'm going to put one on just for kicks. What is a TLAR?

turbo1889

That Looks About Right


As to engine size - normally a 1.45 ft^2 size wing platform calls for a 0.049 size engine in my view of things and a 0.06 to 0.07 if you want to get a little bit of speed and climbing potential. But as I said, I'm used to dealing with thinner air.

As to endurance. I once had a Gillows 1/16 scale Spirit of Saint Louis that I powered with a PAW 0.049 that was outfitted for endurance. Biggest prop I could get it to spin which dragged the engine down to fairly low RPM and made it "lug" while trying to throttle up with like a 10+oz. bladder tank made from one of those thick plastic vacuum pack bags filling nearly the whole fuselage. Radio gear was all built into the wing, no room in the fuselage. Three channel, throttle, aileron, and elevator with the smallest micro-servos I could find nested into the wing. Full load of fuel take-offs from the ground were not possible; hand launched was possible provided you got that big prop spooled up all the way before you launched and didn’t try to climb at all at first until you got your air-speed up. Once you got up to roof-top height or so then you could back off to just about 3/4 throttle where you could just start to hear the engine “lug� and then keep it nice and level and only bank about 10-20 degrees on the turns and didn’t try to add too much up elevator. You could keep that think air-born for a long time. Never measured how long exactly I was just trying to build a scale model that just like the original was designed for endurance – sort of an added level of scaleism (is that a word?). I can tell you this though, I lost her due to trying to get a second full load of fuel put through her while neglecting to change out the radio battery pack for a fresh one after the first run. Lost radio control in the middle of a banked turn and due to being scale with no dihedral and those relatively small tail surfaces. She went into a spiral dive and bit the dirt with a nearly a 3/4 load of fuel, the bag tank ruptured and what was left of her shattered airframe got completely soaked in fuel – beyond repair, no rebuild.

I imagine though your plane probably handles a lot like that one did only yours would fly slower. She had a bigger engine but she was also a lot heavier so probably about the same kind of piloting skills and technique were necessary.

Invertedflyby

My Feedback: (15)

Ah, I hear those are the best flying planes.   I wonder if it would have helped to lower the compression slightly and run a bigger prop on your glider?

turbo1889

looks like while I was editing and adding all the other stuff I wanted to say you responded, might want to flip back and check out my little endurance experiment.

As far as spinning a bigger prop at a lower RPM with a 0.020 on that glider. If I could have gotten one magically dropped from the sky onto my work bench something on the order of a 3:1 geared reducer spinning a big folding prop would have probably been the ticket. Don't think bigger prop would have helped though without doing a gear box.

Invertedflyby

My Feedback: (15)

That sounds like an adventure.   Scale flying to match the real one.   Too bad it got fuel soaked it sounds like a nice plane that could have been displayed really well. 

BMatthews

If it was THAT bad then I think I'm with CP on this one and you need to ditch the throttle sleeve. Also what fuel were you using?

Many years ago I built a 32 inch Taylor Cub powered by a PeeWee. It was 10oz flying weight and set up with the Ace rudder only system. It flew like a freakin' hot rod! The power gave it a climb that got me into a lot of trouble and sadly I only got the one flight out of it due to this.... or rather 1/2 a flight since it since it did some gyrations too close to the ground and split S'ed itself into the "big green thing" and that was the end of it. So at 11 oz you should be getting some decent flying out of this thing. Pull off the throttle sleeve and try some real man's fuel and see how well it works. And don't be adding any head gaskets until you start trying to run it on the bigger props..

Invertedflyby

My Feedback: (15)

I'm using Powermaster Fuel with 20% nitro and 18% synth/castor mix.   I want to put more castor in it but the LHS sig castor is about $14 for way more than I want, I just want a little bit.   And I've read on here the pharmacy stuff isn't degummed or has sugar in it.  

I'm sure it's not putting out as much power as a normal PeeWee, I'm already running it on a bigger prop (6x3 cox) and 4 head shims.  I read a thread in here where someone was running this combo with good results.  I think it looks and sounds more scale like that way.  Maybe one less shim before I have to go to a smaller prop. 

combatpigg

My Feedback: (3)

APC makes a 5.5x2 and a 6x2 that could help.