Breaking in the MP Jet .061

I went out a while ago and slipped a piece of fuel tube over the needle and that fixed the looseness. I took out one shim and ran it. It won't even pop over with the methanol prime. I had to prime it with nitro fuel to crank it. After that it ran faster than it did with 3 shims. Still in the low 14k range, but steady and holds the needle setting fine. Then I stuck my thumb into the tip of the prop. Damn MA props have sharp corners. Nothing a band-aid won't fix. It's the first time I've ever been cut by a prop. Can't go round with one thumb sore, so I stuck my other thumb in the prop. Time to close up the shop. But anyway, it looks like a nice little engine.

Glow engines should be run in with a little smaller prop than what you plan to use later. This reduces the load and prevents the temperature from getting too high before all the surface are properly mated. It will also let the engine rev without being overly lean, which is a good thing. An APC 5.7x3 or 5x3 is a better match. Once run-in, you should get close to 18000rpm on a 6x3 prop.

The needle is a little pain with these, they need a piece of fuel tubing to seal but then they also tend to turn back from the twisting of the tube. So not only are they close to the prop but they are also harder to set right...

Kris, that's what I've always heard too, but I followed the directions from the sheet that came with it. I'll put a 5x3 on it before I run it again, and do some more rich runs. Last night when I ran it lean, I only let it run for 2 minutes before the tank ran dry. When I ran it again before my next post, I only ran it for less than a minute, so hopefully it's okay. It probably ran cooler with the 0% nitro too. I won't be able to get back to it before Sunday night.

Yes, I don't think that you have damaged anything.
Running rich with short times on a leaner setting is all good.

In general though I think it is better to use a smaller prop and use the needle setting to keep the revs on a safe level. It will then rev up pretty high and well while still being on the rich side, while a too large prop can tempt one to push it too far too early.

It's just been on its test stand for all this time. I've oiled it every now and then. But today after finishing my tach race Cox, I got the itch and cranked the MP Jet again. Screw the 0% nitro, I filled the tank with 24% and lit it off. I cranked right up with a roar. The damn thing is Loud! I rigged it up so I could more easily get behind it to adjust the NV without butchering my knuckles... it's rrrreal close to the prop, but once it was running I could not turn it. I pinched off the fuel and tried to turn it and it was too stiff. I backed it out with pliers and shot it with brake parts cleaner. Did that a few times and never could loosen it. Before, it was too loose and spun by itself. I don't know what the hell is wrong now. It's not cross threaded, just stiff. But I cranked it and used pliers to adjust it and it ran great.

I had a 5-1/4x3 prop on it and it would turn up about 20.7k RPMs with all the break-in shims still in the head. Then I re-read the instructions and remembered they said not to exceed 20k. Oh well, too late. I ran 4 ounces through it, tinkering with needle settings, stopping and re-cranking. It's extremely easy to needle, not sensitive at all like a Norvel or a Tee Dee. And it's stupid easy to crank without a spring. I had a chicken stick, but never needed it. I think I'm really going to like this one. I just hope there is a source of parts for it. It's made in Czechoslovakia, and barely written up in broken English.

Now that I know it's operating RPM range and obvious power, I'm convinced I have the right plane for it. An old green plan-built thing given to me by a club member and looks like it's supposed to be a T-28 Trojan Navy plane with a 30-something inch wingspan. That's what it's going to be when I get through with it anyway. Mark gave me some military decals for it too, so I'm going to paint it up real pretty, bolt this power plant on it and let 'er rip. I'll update as it comes along.

that thing needs a super high drag design like a fokker triplane to make good use of its power
I double dawg dare you to put it on a streamlined scalpel or 60% downsized blink
ok that was just sadistic jealousy on my part but it would be a thrill ride if you can handle flying a model like that,I kow full well I`m too rusty on the sticks to handle much more than the fokker triplane,
so I want a COX 020 or 010 size fokker tri and I`m done flying any planes without a throttle lol

ps you are a lucky dawg for having 1 of these engines and keep us posted on it and btw u forgot the video to mak us drool about your engine

Jaspur_x wrote:...ps you are a lucky dawg for having 1 of these engines and keep us posted on it and btw u forgot the video to mak us drool about your engine

Okay, find your earplugs and I'll get a video of it tomorrow.

20.7 Rusty?

Show that engine who's boss.

John Goddard wrote:20.7 Rusty?

Show that engine who's boss.

Still running on low break-in compression, I'll bump it up next time. How fast do you think it should turn? Even at lower RPM I think the HP is really up there. It might just be meant to swing a bigger prop than the Moscow Cheater does. I'm still learning about it, and information is scarce.

Mine have shown similar power as the Norvels, but the Norvels can probably take higher revs (+25krpm) better since they have an aluminium piston (lower weight). As a comparison the .061 Norvels make about 23500rpm on a 5x3 prop and 10% Nitro.

I fixed the stiff NV. I must have hit it with my chicken stick back flipping it, the damn thing was bent. I took the spraybar out and straightened it enough to make easy to turn, and now it's still just tight enough to hold still while it's running, so that's better than before. I also learned that this spraybar has two horizontally opposed spray holes in it. You can't see the holes looking into the bottom of the venturi. Never seen one like that before.

I promise I haven't forgotten the video, so stay tuned.

Alrighty, here's an entertaining little movie for your viewing pleasure.
As always, fullscreen is enabled. If it's jerky drop down to 480p resolution.

What prop size was that?
They are load enough with the muffler on them...

The first run was an MA 5.25x3. The second run was an APC 5.5x2.5. I had 2 head shims in it and 24% nitro fuel.

Is there a reason for the head to be on sideways?

Godsey3.0 wrote:Is there a reason for the head to be on sideways?

Yes, absolutely positively, there's a really good reason... I didn't notice I had re-mounted it that way after I took it off to count shims. I'll rotate it before I run it again. Good catch, Rolla.

EDIT: I just noticed in the intro, the head is on the right way.

Kris, you've mentioned MP Jet RPMs before. I wonder if you realize this is a PB, plain bearing MP instead of the more common BB, ball-bearing. Maybe my PB doesn't rev as high as yours, if you have a BB.

I haven't tried the muffler yet.

[quote="RknRusty"]

Godsey3.0 wrote:
Kris, you've mentioned MP Jet RPMs before. I wonder if you realize this is a PB, plain bearing MP instead of the more common BB, ball-bearing. Maybe my PB doesn't rev as high as yours, if you have a BB.

I haven't tried the muffler yet.

Well, I happen to have all three versions, glow in both PB and BB, plus some Diesel ones (BB). The muffler doesn't do that much to reduce the noise (large outlet) but it doesn't reduce the rpm much either. Your rpm's are probably fine, it is always dificult to compare when different props and fuels are used.

Here are some different mufflers they have used though out the years;

Something I have experienced with the MP Jet .061 PB is its ability to swing a relatively larger prop without slowing down too badly. I flew a Sig Hummer on an MP Jet .061 PB using a MAS 6.5X3 formula series prop and it spun the prop up very well and gave the approximately 16 oz plane unlimited vertical. I was told about the engine's abilitly to happily spin bigger props by Mr. Ed Carlson.

Hey, Bob, good to hear from you. I plan to use a 6x3 on the plane I'm currently fixing up for the MP. But it won't weigh 16oz, maybe 10. I might need to try the 6.5x3 and if it's still too much engine for it, I'll just have to drag a brick or something. I am planning to get a scale so I can weigh parts and balsa. I think Walmart has a food scale that'll do the trick.

icare-icarus.com has new MP-Jet engines and some spare parts.

fit90 wrote:icare-icarus.com has new MP-Jet engines and some spare parts.

Hi, Bob, good to hear from you.
I'll check that out. I could only find a source in Australia before. I never did fly that .061, it's still on the test stand getting oil every now and then, That plane I mentioned above got the Big Mig you gave me. That was the Refried Bean, the one in my avatar. That one is currently on a Baby Streak. Then I had a T-28 for the MP, but it turned out to be dry rotted with ancient Ambroid shriveling up. The next 1/2A I build gets the MP. I can't bare to let it sit forever. I kind of feel bad about not having used it yet.
Rusty

Rusty,

Happy belated birthday. I hope you had a great day. I am trying to get back into R/C flying as I get some spare time. I want to do it with these small engines. I have some really good throttled engines I want to try out. I really like the MP-Jet line of engines. I will post my results as I progress. It is always great reading all the posts here.

Bob

Bob, you got me excited now about this MP Jet.061 BB Factory Racer. I just checked out icare-icarus.com and am going to snatch up some glow plugs before they disappear forever. I wonder how it will do on bladder pressure. Might have to make an NVA out of one of Texas Timers' generic 128 tpi spraybars. That worked great for me on a Norvel. I just searched and found your old thread on RCU about the BB Racer. I can't wait to show up at my club's 1/2A day with this exotic machine.
Rusty