combatpigg

My Feedback: (3)

It is about time to build a plane for this engine. The speed plane project is on hold until I get the fuel system sorted out. That plane needs to have a Tetra tank retrofitted, I couldn't get the bladder system to work. I figure this delta will be easier to get a working fuel system with, then I'll transfer what is learned here into the speed plane. This delta has 31" of span and will probably weigh 2.5 pounds by the time it is done.

ChuckL

My Feedback: (2)

Sweet looking delta, I have a serious addiction for deltas every time I see a new one I gotta try it.

Razor-RCU

My Feedback: (50)

combatpigg- You disgust me with your building skill! Let me guess, you can also do Algebra and juggle chainsaws?

That is one awesome looking delta, the cowl is super impressive! I can barely assemble a Whiplash [X(]

Keep us posted and let us know how it goes-

P.S. What is the story behind that K&B?

freakingfast

My Feedback: (3)

Those servos look like minni's, If they are you may have only part of one real fast flight before the servo blows and lose all that nice work. I wouldn't use anything less than JR 8611's ($$) on a 200 mph capable ship like that. Deltas need a much more robust servo than a pylon racer.

combatpigg

My Feedback: (3)

Thanks for the compliments!

I use blue foam to make the forms for the glass work. Then cover the foam with clear packing tape. Spray 3M77 on 2 oz cloth and form it to the form. Now put on a latex glove finger and saturate the cloth with medium CA. The hatch covers are 2 layers, the cowl is 4 or 5 layers.

Nice catch on the wimpy looking servo . It has 48 ozs of torque, so I figured it was worth a try.

The engine is one I picked up for $65 at an auction. I lightened the piston and streamlined the rod. The exhaust timing was raised to 180, but only the center third of the port got raised. I rebalanced the engine by grinding a couple of divits in the counter weight, trial and error work.

I still need to rig a fuel shutoff to pinch the feed line, then there still is a bunch of final fitting and sanding. K&B epoxy paint will be used to protect the parts that are cast with CA glue. In another week it should be ready to roll out. [8D]

freakingfast

My Feedback: (3)

Over 150 ozs of torque, metal gears in a standard case size might work, if you don't get a hint of flutter on large delta control surfaces (ask any high speed whiplash or diamond dust flier). Remember, you can't fly a delta with one working control surface and you won't scrub off much speed before you hit the ground. I hope your right and I'm wrong.

Razor-RCU

My Feedback: (50)

Well... I can only speak to the Whiplash (I have had 2 going on 3) the biggest reason one would need torque and MG servos is the Whip taileron skin is SUPER hard to move- even on the X version...

I joke about using 645MG's (133oz. @ 6v) that it takes 100 oz just to move those tailerons (just sitting still) and 33 to fly. This is obviously an exagerration but Combatpigg's delta will not have much throw I bet... At that speed it only takes 1/16th or so- I also bet he seals his hinge areas.

I personally never recommend anything less than a 645MG on 4.8V (107 oz.) simply because they are soo inexpensive! I bet some 605BB's would work just fine though----

HighPlains

My Feedback: (1)

CP, thought you might enjoy a few pictures of a Klatter & Bang .40 pylon engine. This one made it's last competition run at a Formula One race in Phoenix years back. The small opening under the exhaust port was known as "freeporting", which allowed additional air into the case for more power. Clarence Lee did this engine originally, but it was later rebuilt with parts from another engine, that included a knife rod.

combatpigg

My Feedback: (3)

HP,That is a wild looking mod, auxillary sleeve porting I guess you could call it.

I figure the elevons will only have to move at high speed 1/16" to fly a speed plane type pattern. I guess hot dog rolls on high rate will test those little servo gears out ...[X(]

HighPlains

My Feedback: (1)

OK, now that I had a chance to make you sweat about the rod mod, I'll tell you what really happen. These engines have a nice shiny band around the bottom of the crank to "stuff" the crankcase. Underneath the band is the cutouts on the crank disk to provide the counterbalance. What I think happen is the band broke (seemed to be a problem with the engine when prop'ed above 21,000 on the ground according to others at the time. With unload, they would be about 26,000 in the air. Anyway, that one was prop'ed to run slightly above 22,000.

Your mileage may vary. Of 10 K&B racing engines I had, this was the only one that split and spit it's guts out.

combatpigg

My Feedback: (3)

Such a neat little hole.......of all the things that could go wrong, that is a strange reason for an engine to blow. I'm just going to ignore the red line warnings and run this thing until it pukes. Hopefully it has a common foot print or at least beam spacing with some other strong runners.

combatpigg

My Feedback: (3)

Here is a look at the fuel shutoff. Access to pull the feed line off for refueling just isn't there, so that is why there is a T fitting in the feed circuit. I can reach in with hemostats through an access hole and pull out the overflow and the extra line that is part of the feed circuit, un plug both lines and fill the tank until fuel comes out of the overflow tube, then cap off both lines and stuff them back into the engine bay. Not to bad of a ritual to go through for refueling. I am hoping enough positive pressure is developed from tapping into the exhaust header flange, to pressurize the tank, it might need a check valve to maintain pressure, but we'll see.

AIRFREAK-1

The K&B 6.5 is a sweet little engine when set-up correctly, just be careful not to run it too rich because the crank pin is pressed in, and it will get loose. Check the area around the crank pin for cracks, and if there are any look for another crank, because it will break across the pin boss. Also I tried a lot of pipes, and the MACS standard 7.5 cc pipe worked the best. I love your design it looks awesome! What prop, pipe, fuel combo are you planning to use? Good luck with your first flights! Regards, Scott.

combatpigg

My Feedback: (3)

Scott, I'll have to remember that recommendation for the 7.5 cc pipe, I don't remember which size this one is, but it is made by Macs. This engine seems to like nitro, I keep raw ingredients, I guess I'll try 50% in it. The last delta I had that was this size performed well with a 7.2x8.6 APC and a OS .32, so I figure the K&B should do OK with the same prop on this plane.

combatpigg

My Feedback: (3)

Ready to go, just gotta set the needle and give it a throw.

bob27s

My Feedback: (19)

Very nice

Razor-RCU

My Feedback: (50)

Looks outstanding!

When is the maiden?

combatpigg

My Feedback: (3)

Thanks, BOB27. It flies just as nice as the one that crashed last year with the OS.32. It tracks, rolls, even flies the exact same speed [ or so it seems], I'm disappointed it isn't much faster!! I ran it yesterday with .15% nitro fuel with about 25% lube, some castor, K&B 1L [cheapo] plug, and APC 7.2x8.6 prop. The OS ,32 would run all day with this set up at 18,000 and rarely burn a plug. The K&B .40 was only giving 18,700, plus I'm not able to back the needle out far enough to richen the motor to anything close to a 4 cycle. Bear in mind that it is running a homemade venturi, Nelson remote needle valve assembly and tetra tank that is getting pressure from a tap at the header flange. I put about 6 flights on it and each time the engine quits abruptly [without sagging] after only burning 3 out of the 4 ozs of fuel in the tank. For you guys with experience running these suckers, what's wrong with my set up? Today I mixed up a batch of 50% nitro, 20% castor, 10% Klotz, 20% methanol and the rpms improved to 20,500, but the same general symptoms are occurring, except the plugs are obliterated and the engine is quitting after a minute real hot. there is no point in me continuing with this until I make some changes. I suspect the venturi might be too big. I also wonder if I should move the pressure tap to the fat part of the pipe? I would like to be able to get all of the fuel to go through the engine before the plane lands. The Nelson remote needle was designed for high pressure bladder systems, but it seems like it should work for suction too. That's my sob story in a nut shell, maybe one of you guys could save me some needless thrashing with some sage advice? { Don't tell me to buy a Nelson RIRE though]

bob27s

My Feedback: (19)

sounds like the pipe/engine/prop are seriously mis-matched.

If its running at 18-20K rpm, that is likely what the pipe is tuned for at the moment. Pipes work to boost RPM, but they also work as an engine governor, as they prefer to operate at the rpm they are set for.

Add some prop to that sucker. Just for starters, put a regular 9x8 on it.

And if its a big venturi, its going to need either crankcase tank pressure or some REAL good pipe pressure (try a check valve in the pressure line)

MyWay

Combatpigg , First off, really like your new plane, nice work. My thoughts on your problems. Your using way to much oil and too much nitro. That engine should run better than 22,000 with only 15% nitro and 18% oil. The venturi size of .350 should be fine. Your tank is to far back and your lines inside the tank look like they are touching the top of the fuel tank. The engine might need a little more air to run cooler. Have fun and good luck.

deckerv

My Feedback: (21)

LOL... You're not kidding either!!! I have hitec digitals in my Whiplash, and one fateful flight the servo arm screw backed out and I only had one elevon. Didn't fully realize what happened till I managed to get it to straighten out and tried to turn to do an emergency landing. That thing pulled a lawn dart into what luckily was freshly plowed and very soft dirt. The only damage was that it snapped the motor mount off. some drilling, carbon fibre tubes, etc.. and we're good as new again, but I learned that a tiny tiny drop of thread locker on the servo set screw is not that bad of an idea

Lookin good Combatpigg!!

Razor-RCU

My Feedback: (50)

Decker- What digitals on the Whip? I am waiting on 5645's for my Whip elevons @ 6V

I have never used thread-locker on servos, but will now!

combatpigg

My Feedback: (3)

thanks for the replys, some good food for thought there. I decided to repeat the successful runs I had last year with it, using a latex bladder that I pump up with 4 ozs of fuel. Same results as last year, almost 24,000 rpm and I was able to back it off to 22,500 and it was still on the pipe, there should be excess fuel for unloading now. The venturi I made was much bigger than the carburetor that came with it, I don't remember how big I made it. I guess it is too big for suction. All is well now, [until I start popping bladders every other run] . This is what I tuned the engine for last year, raised the exhaust timing, lightened the piston and streamlined the rod, and shortened the system for best rpm with the 7.2x8.6 prop. Back in the day, wasn't the hot prop for these engines the Top Flite 8.5x6.5 maple? Besides that, I thought these engines were set up for high nitro Formula One Class?. I got this engine off a retired F-1 racer, [or so he says]. I'll give the 9x8 a try, but will probably have to start over with an uncut header to tune for a lower band. Anyway, it's turning up good enough now to make the next trip to the field something to look forward to.

bob27s

My Feedback: (19)

If the fuel delivery ended up being your problem, just change that. Keep the prop you have now.

Props I seem to recall running on the STX40 were 9x7.5 topflite pylon props worked down to about 8.2x7. The K&B was not that far off.

Just keep those saftey goggles on when filling the bladder

combatpigg

My Feedback: (3)

My R&D budget for home made venturis might need to be increased if I'm going to get that engine to run on suction. So far I've got 50 cents invested in aluminum, most of it ended up on the floor . I wonder if a long stack would permit the large diameter air intake but still develope better suction? A more convoluted approach would be like what is done on a Holley, have a booster venturi [like a brass tube] stationed inside the larger, main venturi. The fuel gets fed into the inner [booster] venturi, and the vacuum signal there is very strong.