spaceworm

Ah, but thry say it is NOT a glow conversion engine!?!

BTW, is Rattlesnake Raceway still open out there? Hap Sharp and Jim Hall still around?

Regards, Richard

airborne2.4

Yep, it's not a glow conversion engine. I'm sure Jody will give me a hand and get it running the way it should with the cowl on or I'll just fly with the colw off

glasairdriver

Heli-NuBee
How is the engine working out in your Nitro Planes P51? It seems that some people are having a lot of dead stick landings with fully cowled engines.
Can you post some photos of the engine area? What muffler did you use?

sprgfvr02

My Feedback: (1)

I'm real interested in this particular issue, as I'm just starting to build my TF P-47.

glasairdriver

I read some bad reviews of serevice from Nitro Planes so I have also looked at the TF P-47. It has a much more open cowl. The cooling would probably be much better. I also like the flaps and cockpit detail of the P-47.

ec121

My Feedback: (2)

Some people say it doesn't matter, but I personally don't care for the carb pointing into the prop blast or the looks of it in the cowl. Looks to me like the mixture would possibly change with airspeed. The Evolutions, MVVSs, and the OS gasser do it that way. Maybe the carb throat velocity is so much greater than the prop blast that it doen't matter. Easy enough for me to avoid. I don't have to buy them.

aussiesteve

airborne2.4
Looking at the photos of your cowl, I think you are most likely overheating the engine.
Whilst there are a lot of holes in it, many face the incoming airstream and the ones that could work as outlets are probably quite low in efficiency.

Try placing some "Shrouds" in front of the "outlet" holes to help create a low pressure area and extract air throught he engine cooing fins and out the cowl.
I don't have any photos of what I mean here maybe someone will post some

Here are some words that may help in the interim

[link]http://www.troybuiltmodels.com/ns/learn/engine-air-cooling-easy-how-to/[/link]

aussiesteve

I knew I had seen the photos somewhere - try this link (Hope I aren't breaking the rules by posting it, we're only trying to help after all)

[link]http://prme.nl/forum/viewtopic.php?t=37&sid=02ef3b6e735959e17033de23e82 21518[/link]

airborne2.4

Thanks for all the help guys, I appreciate it.

spaceworm

Does the carb facing inot the prop blast matter more, or less, with a gasser than a glow? Regardless of whether it is a glow conversion or not, it is built like a typical glow engine, with rotary intake on the crank and bearingless connecting rod ends. Has the head fin area been sized up from the glow engine it was not-converted-from to account for the hotter burning gasoline? Also, although I have not seen it addressed, is the crankshaft supported fore and aft or just forward, like a glow engine? Has anyone tried converting it to glow to see how it runs?

Sincerely, Richard

Heli-NuBee

Hey glasairdriver,

I have only flown my JBA powered Nitro Planes P-51 on three occasions. The first time out the engine ran fine but I had control issues on the second attempted flight that ended the day. The second day out, the engine ran great and the flight was great but the muffler had come loose and one of the muffler bolts was lost that ended the flying day. I am using a J-Tech pitts style muffler and the mounting bolts are now drilled and safety wired. The third time out, I also experienced the sudden unexpected engine flame outs. On both flights, the engine quit suddenly on about one half of the expected flight time at full throttle while doing a manuver. I judged and landed the first time without incident but the second landing was a bit long and the plane landed in the rough resulting in a damaged landing gear mount and ending the fly day. I have not found time to repair the plane and fly again but I will in the near future. I did richen the high speed needle about 1/8 turn after the first flight but it did not help. I plan to richen the high speed needle more before I fly again. My Nitro Planes P-51 looks and flys great but it does have one nasty habit of wanting to spin in on the left on take off. It takes a lot of right rudder on take off and it is still a hand full. I have been flying RC aircraft since about 1970 and I can say that this plane is the most difficult plane I have ever had on take off. After the plane gets a bit of air speed everything is normal and it is a pleasure to fly and land.

Best wishes and good safe flying.

Heli-NuBee (Roger Anderson)

VampeD4

My Feedback: (80)

4-Sale one JBA 15CC run about 15mins. make me an offer [email protected] ( it run fine i think it my be the oil you can are using. try http://www.lawn-boy.com/productinfo/parts/oil.html )

Thanks

if you need pics email me

airborne2.4

Ever thought about using Stihl-HP-ULTRA:
http://cgi.ebay.com/Stihl-HP-ULTRA-2...item2a0d9e44b3

Lifer

My Feedback: (1)

Heli Nubee,

For the left-hand spin issue you might try rebalancing the airplane so the right-hand tip is slightly heavier than the left. Should help with the described issue.

Best of luck.

ec121

My Feedback: (2)

Could also be trying to lift off into too steep an angle and generating a tip stall. I have seen some smaller warbirds at our field lift off with the wings snapping both ways on the edge of a stall. I don't think the pilot knows what is going on and just tries to yank it off the runway. Fortunately, power compensates for lack of skill. I had a .40 sized Decathlon and a clipped wing Cub years ago that educated me about using too much elevator on takeoff. Warbirds want to tip forward over the nose because the gear is almost on the CG and the drag of grass pulls back on the wheels as the thrust pulls the nose forward. As a result the temptation is too get it in the air too soon to avoid having to use the elevator to balance the plane as it accelerates during takeoff. Landing is the same scenario. The plane rotates over the tires into the ground. The cure is to hold a tiny bit of up elevator and let it run until it gently lifts itself off into a gentle accelerating climb.

R/C Addiction

So I finally got around to starting my JBA 15cc engine. It seems to run pretty well and I am sure will get better as it breaks in. I followed the directions to the letter and ran it for a total of 1 hour (in 15 minute increments) allowing it to cool in between runs. My gas mix is Stihl Ultra HP at a ratio of 25:1 and I am using a Master Airscrew 13X8 three blade prop. My tachometer said I was spinning at 9400 RPM. I used an electric starter to get mine running...didn't have much luck trying to start by hand. Has anyone else had any starting difficulties using the hand propping method? Also, I am relatively new to gas engines and all the engines I have are still not considered broken in yet (low engine time) and they all throw out quite a bit of the black exhaust residue...will this clear up with more running time?

Lifer

My Feedback: (1)

Mine was reluctant to hand start as well. First flight yesterday on a WM AT-6. Seemed a little over-propped with a 15x6. Plan to try a 14x6 next. Will try to richen the low speed needle a little for the hand start issue. Ran good and was reasonably quiet.

airborne2.4

Yes.

airborne2.4

I covered the hole and carefully adjusted the HS and LS. The engine runs perfect now!!! but I have another issue. This thing is putting out so much power its taking the Ultracote off of the stab and elevator lol lol

frieshoo

My Feedback: (20)

Ran my JBA 15 this weekend.

2100 feet above sea level.
65 degrees (high humidity)

20:1 Sthl Ultra HP

Master Aircrew K series 15x4 (the only thing I have in the prop range).

Mojo 60 6.5lbs.

Connect my RC Excel Tach.
TX on.
RX on.
Ignition on.
Full Choke
10 flips
Pop
Choke off
High idle
2 flips
Running.

I ran the engine up to 'blow it out'...
Set the throttle stick at 3500-4200 rpms and let it run a good 5 minutes.

Shut the engine down. Check the temp of my PE-2 gauge... 190 degrees...

Let the engine cool down for about an hour.

TX on
RX on
Ignition on.
High Idle.
2 flips.
running.

I let the engine warm up again to 190 degrees.
WOT 11500rpms on the tach.
1/8th of turn in on the high needle, and she went flat.
1/16th of turn out on the high needle, and I got 10800 rpms. Touchie needle.
Didn't touch the low end.

Now, my issue... maybe..

I set the idle at 1800rpms (granted this is only the second 8 oz tank of fuel). Idle is great actually.

Transition to the middle stick sucks. (and yes my throttle is linear. I use the heli tail rotor push rod technique of finding 1/2 throttle, fool proof)

Idle = 1800
1/4 = 3300
1/2 = 9000!!!!!
3/4 = 9500
full = 10500

It's like a peaky tune pipe setup... it literally jumps to 9000 with one click of throttle.

I'm going to load the engine more with a better prop...because it's running cool with the MA 15x4.

I'll leave the needles set until I get a gallon or so through the engine.

FWIW, with the mojo/15cc seems like a good setup... I would love to get my transition better.... say around 1800 - 7000 - 10500..

It was real windy so I didn't real good feel for power/weight..

frieshoo

My Feedback: (20)

Check the wheels, and make sure they are turning on the axles freely, and with close to the same speed. Years ago, I had a slow poke that turned hard to the left... of course all the know-it-alls at the field wanted me to add more right thrust... but I told them it didn't pull to the right in the air.... My left wheel was 'sticking' and causing this hard left...

airborne2.4

[/quote]
You betya

spaceworm

You might also want to check for toe-in or toe-out and put a little toe-in in the main gear, if there in none. Helps keep the plane on track on takeoff and of course does not affect the flight characteristics. I do this with all of my taildraggers and it works for me. Once you are in the air, the rudder and ailerons have to be used of course.

Good luck.

Sincerely, Richard

sprgfvr02

My Feedback: (1)

I also had issues with hand starting. I have about an hour on the engine on the stand. My TF P-47 is ready for the engine to be mounted. I'll do that this week. I'm OK with using the electric starter. Saves on the forearm. I've tried hand started several times, but just haven't got it yet.

I also have the dark residue from the muffler. I've been running the engine with a 14X7 prop. I've ordered the Jtec Pitts muffler which should arrive sometime next week.

I'll take photos and post them when I have everying in the cowl and ready to fly.<br type="_moz" />

a1pcfixer

My Feedback: (7)

Glad to have helped you!

As to the too much power....ain't no such thing![8D]