Build Log: Converting a 31" Super Cub to .049 Power (revisited)

cribbs74 wrote:

microflitedude wrote:

PV Pilot wrote:

microflitedude wrote:I do not have the tank from the dragonfly. Aluminum 8cc stunt tank. Check back to page two I think, there are some pictures. Maybe page 1 too.

Will leaning it out help? After the flight, I dropped some fuel on the head - it immediately boiled off/vaporized.

Ok, gotcha. well, with that tank you are fighting a losing battle. It's a Control line tank,,as such, it is meant to have the pickup tube positioned to the outside,, for fuel pickup by centrifugal force (fuel slung to the outside of the tank as the model swings in its circle). Stuff you probably already know. A clunk style tank is preferred for flying R/C. With your control line style tank, fuel sloshes away from that pickup when you flip upside down, turn to the left, turn to the right, ect. and you get what you are getting now,,erratic running.. I know bucks are tight, but once you can,,purchase a clunk tank, a tank style backplate and start there first before moving on to flight tuning. It will run fine sitting motionless, but once the fuel sloshes during flight, you get a crazy motor.

Lets fix that issue first if you can do so, then move onto flight tuning, which will be the easy part.

Thanks for the info, that explains all of it. I wish I knew this before. I seems like with all the FF and RC mods I have seen this would be ab bigger problem. Will I damage the engine the way it runs now?

I have a Sullivan 1oz clunk tank, (NOT a fun tank to build) which I think is the smallest clunk tank out there other than the dragonfly/RC bee. There is no room in the plane, though. Possibly on the wing? This is going to be more trouble than it's worth.

Micro,

I know that the "Perfect" brand of tanks goes all the way down to 1/8 oz and everything in between. Cox International has a 3/8 oz and another sub 1oz size available. I don't believe they are a clunk tank like the sullivans but, the fuel outlet is at the bottom so it will gravity feed. Basically the only time it will sputter is when the fuel is half tank or less. Now keep in mind I have never actually owned a perfect tank so they may in fact have a clunk. Maybe someone else here knows?

Hope that helps a little.

I have one, I think it is 3/4 oz. No clunk, I think they use something called "uni-flow" pipe setup.

You use a pressure tap with a uniflow if I remember correctly. You can make a mini clunk out of a rectangular shaped pocket sized Purell bottle that holds about the right amount of fuel. I know you have location problems. If you slap a KB backplate on it. That will free up enough room for a little shampoo bottle. It may look clumsy, but it might just fit one way or another.

One can dislocate his arm throwing this plane, trying to get it moving past stall speed...

My brother has the stock electric one, and I swear it weighs half as much!

Been doing more work, sealing the nose with a light layer of epoxy. Strengthened a few structural points that were flexing too much. I also installed a 2.4ghz JR receiver. Drew two sets of black bars on the underside of the wing, and used up the last of my "Cox Powered" stickers.

I am currently looking into mounting a Sullivan 1oz (or metal 3/4oz) tank on the wing. This would boost flight times up ten minutes. The biggest problem is weight, as the tank an and ounce of fuel is quite heavy. To compensate for this, I will not use the landing gear, removed the cowl, (was messed up anyway) and I will use a battery that is twice as light. I will fly it with the muffler closed to make it quieter and bring the power range down.

I have not been flying it at all. There is just nowhere close to do it anymore. Maybe I can show it off at my spring Fly-in. Control line circles will be integrated this year, maybe I'll be flying CL by then.

Updates, for anyone who cares to read them.

It still hasn't died.

That being said, the past few days I spent reading, working, reworking, and testing. I saved about an ounce by trimming cables and glue, replacing the old damaged throttle servo with a smaller, lighter one, and ordering a much lighter 180mah receiver pack. Cleaned out the throttle pushrod which had frozen inside the tube.

It weighs 10.2 oz. (9.5 w/o LG) As a lekkie, it weighed a feathery 7 oz. Wing loading is the only real "issue" left.

How long will a 2s 7.4v 15c 180mah Lipo last powering a micro RX and 3 sub micro servos through an ESC regulator?

Also, is it safe to spray brake cleaner inside the needle valve orifice? The engine doesn't come off, and I'd like to clean it a little. It has a teflon reed and I think a plastic housing.




They yellow battery is old.

Brake cleaner exactly what I used at the weekend
On the Dragon Extreme Matt.
All good and engine now breathing properly.

If you're fretting about tank don't forget the
'Wedding Bubbles' bottles about 2or 3 at the
Pound store 17cc capacity and weigh 4grams.

John Goddard wrote:Brake cleaner exactly what I used at the weekend
On the Dragon Extreme Matt.
All good and engine now breathing properly.

If you're fretting about tank don't forget the
'Wedding Bubbles' bottles about 2or 3 at the
Pound store 17cc capacity and weigh 4grams.

Thanks, I'll see if I can find a can in the garage. Wedding bubbles?

Is that the mini super cub?

WingingIt74 wrote:Is that the mini super cub?

Yep. My first plane. My pride and joy.

microflitedude wrote:

WingingIt74 wrote:Is that the mini super cub?

Yep. My first plane. My pride and joy.

Ok, that's why the proportions looked different.

Here's my SuperCub (larger version) 47.8" Wing Span

Nice plane. Got any floats?

microflitedude wrote:Nice plane. Got any floats?

Specs on my $uperCub
http://www.horizonrcflyers.com/forums/showthread.php?t=1711

microflitedude wrote:

John Goddard wrote:Brake cleaner exactly what I used at the weekend
On the Dragon Extreme Matt.
All good and engine now breathing properly.

If you're fretting about tank don't forget the
'Wedding Bubbles' bottles about 2or 3 at the
Pound store 17cc capacity and weigh 4grams.

Thanks, I'll see if I can find a can in the garage. Wedding bubbles?

There ya go Matt



And if you don't have a local Pound (Dollar) store,-

http://www.ebay.com/itm/Celebration-Time-Champagne-Bubbles-Weddings-10-Bottles-/120994977201?pt=UK_Home_Garden_Celebrations_Occasions_ET&hash=item1c2bdcd5b1

Took it out to fly yesterday. Started without much trouble, ran great on the ground. As soon as it started moving it began to sputter and lose most of it's power. All the usual stuff. I don't remember it doing this without the throttle, so it may be related to to that. tried running leaner, didn't help. Tried running richer, helped a tiny bit, not much. Once I was able to get it up fairly high, and make a decent glide back down to the runway - first landing free of a nose over. It's getting annoying. It would be so much more fun with all its power. Having second thoughts on bringing it to a crowded fly-in. They probably won't appreciate me running on the field every 2 minutes to retrieve a plane.

Everyone thought it was cool - from the 13 year old who had never seen anything like it, to the older guys bringing up old memories.

One guy suggested I convert it to electric.

I managed to break the battery tray/LG support in half, the last solid part of the plane.

Dunno what you're using as the tank Matt but with my recent 'experiences' I'd flush the fuel line and needle valve with brake cleaner then perhaps clean the reed.
I doubt the throttle is upsetting it.

John Goddard wrote:Dunno what you're using as the tank Matt but with my recent 'experiences' I'd flush the fuel line and needle valve with brake cleaner then perhaps clean the reed.
I doubt the throttle is upsetting it.

Standard 8cc tank on a Black Widow. There are more pictures further back in the thread. I flushed everything I could get to with brake cleaner.

I'd like to try the larger cub, I think it will work.

microflitedude wrote:

John Goddard wrote:Dunno what you're using as the tank Matt but with my recent 'experiences' I'd flush the fuel line and needle valve with brake cleaner then perhaps clean the reed.
I doubt the throttle is upsetting it.

Standard 8cc tank on a Black Widow. There are more pictures further back in the thread. I flushed everything I could get to with brake cleaner.

Did you connect the fuel pick up to aerosol and spray with N/V in place (say open by your running 3ish
turns out) and afterwards with nv removed?
With nv in place you should've had a nice fine atmosphered spray
Have you done a suck blow test on the reed?
After these it's only really fuel and plug imo.....

Keep at it tho Matt I'm rooting for ya Lord knows I've felt like chucking the Cox towel in over the last few months but when it goes right it is worth it, if for no other reason than to see the faces of all the
'un/disbelievers.

Final thought my Killa B'stard's laid up at the mo, didn't want to run turns out it's the ball needs restting
on the piston.

I can't really take the engine off, so I sprayed it down the needle orifice and the vent tubes.

Ok
What you've got to do then Mat is..
I'm assuming you're able to connect the can to the nv housing via a tube of some sort?
Pinch the feed pipe from the tank then spray your brake cleaner.
That way the blast will only have one way (through the nv jet) and dislodge any crap
in there.
Only use sort bursts cos you don't want to dislodge the reed.
Good luck ma man.

PS.
if this fails that engine is gonna have to come off.

If it runs better richer you may have an air leak. The Widow on my Bean did the same thing. Fine on the ground and then like a black turd when airborne. Turned out the venturi seal, tank backplate amd crankgasket where leaking.

Close the NV and block off the overflow and pressurize the tank. Look for bubbles!



Ron

It just passed the leak test. It has before, as you could pinch the vent tubes and it would stop within a couple seconds. It runs like a top on the ground, and will through the whole tank. I can even turn the plane up or side to side with no problem. But as soon as it starts rolling on the runway, it bogs down. The pickup tube would be sitting against the backplate, so its getting plenty of fuel. Maybe the pickup tube got bumped straight out when it crashed the first time... That would explain the fuel moving past the pickup tube resulting in shorter flight time... Hmm...

I REALLY don't want to take the thing off - it's attached with a good bit of hot melt glue and epoxy. Maybe I could drill out the steel studs and pull it off without having to remove the firewall... But I doubt it.

Someday it will come gliding down with a freewheeling prop, indicating a failed piston. Did I mention the uncomfortably loose ball joint?

So much work on an overweight plane that flies like crap. I'm not through yet though...