pianori

My Feedback: (2)

It is a silicone tube; a neoprene tube works the same. I cut the aluminum muffler tube and put the silicone extension so that I can soften the exhaust sound. It was too noisy for me. This seems to work as far as reducing a little the muffler noise. I typically do it to all my gas planes. I bought the tube online from a place that sells it by the foot. I do not seem to remember exactly where, but I did a Google search and typed "silicone and neoprene tubing" that is how I found it.

pianori

My Feedback: (2)

Well I decided to meet with Tom at Wildhare RC yesterday to run engine tests and compare the TOC 53 and the MT 57 with the same props back to back.
Both engines were stock no modifications were done to them. No pipes, or canisters just the provided muffler. The timing and the carburetor reed were not changed. The timing on the MT 57 was set to 12 degrees (that is way too low!). The readings with different props were:

TOC 53 23 A Vess 6750
23 X 8 bunny (xoar) 6500

MT 57 23 A Vess 6750
23 X 8 bunny (xoar) 6500

We also run one of Tom’s modified TOC 53 and the readings were:
TOC 53 Modified 23 A Vess 7000
23 X 8 bunny (xoar) 6780

pianori

My Feedback: (2)

This did not turn out to be a good weekend for me at all!

Well it seems that both engines from factory they are close except the MT 57 being the lighter engine.
You should know that I did not change the timing on the MT 57.
After the test I went to fly the plane at the field.

That turned out to be a bad day as I was getting RF interference with the new installed electric smoke pump. I ended up getting a major glitch forcing me to land the plane and braking my favorite prop (Vess 22 A).
You can see the video of the flight here:
[link]http://www.youtube.com/watch?v=W1TK8ytBSuc[/link]

pianori

My Feedback: (2)

On Sunday morning I decided that it did not make sense that the MT 57 would run the way it did so I decided to change the timing to see if I could get better numbers. Only this time I did not have the Vess prop any more since it broke the day before. I could only test with the bunny (Xoar) 23 X 8.

The problem with the MT 57 timing is that it is set too low from the factory (11 to 12 degrees). From previous experience most gas engines that I have dealt with especially running with the Rcxcell ignition like to run around 28 to 31 degrees BDC. It seems though that as installed from the factory you cannot achieve the timing needed. After installing a hose clamp to secure the pickup sensor at about 28 to 29 degrees I tested again the engine ( I think that Soarich also mentioned that the timing should be about 28 degrees).

Holy C#@$%^&!!! What a difference the timing made. With the only prop left for me to test (Xoar 23 X 8) the engine tacked 6750 RPM. What a difference I was very happy.
After installing a switch to the electric smoke pump (and fixing the RF issue) flew the plane again.

What a difference. The setup flew perfect. I could have possibly tuned more the timing, but I guess the RC Gods were not on my side this weekend.

While flying the plane up on a vertical the bolt that held the spinner together sheared off. The spinner hit the prop breaking it. It took me two seconds to figure out what happened, but it was too late by then, the vibrations from the broken prop were too high so it destroyed the fire wall engine mount and the cowling. The engine stopped and at that point as the plane was flying inverted. I did the best I could to turn it back around and ended up smacking it on the ground on its belly. I am so upset now.

The engine suffered some damage (5 fins broke and one of the stand offs bent), the fuselage and one of the wings were trashed.
The good part is that I managed to get some nice pictures on my previous flight so I am sharing those with you.

That “one last flight� always gets you. This was my first airplane crash. I have been flying since 14. It is not a matter of "if one will crash, but a matter of when".
On a good note, I will inventory what is left and put another plane together.

davemilw07

OUCH!!!!! Sorry to hear about your misfortune. [sm=frown.gif]

I've had a lot of "bad landings" myself, so I know the experience........ [sm=cry_smile.gif]

pianori

My Feedback: (2)

Thank you for your support. It took me a couple of days to snap out of it. Sunday night I did not sleep well. I kept on thinking over and over the plane crashing. All that work, it is discouraging and frustrating.

On a good note, I started a new project now. Tom at WildHare set me up with a new plane. Only this time I decided to go with an EDGE 540. Larry from Ls Pro engines is sending me a new stand off to replace the one that bended.

So here I go again to put in a whole bunch of time, hard work, hope, and expectations to put together a new setup. Let’s see how long this one lasts.

soarrich

My Feedback: (98)

Crashes suck, but they happen.

Did you check your spinner out after that rough landing due to RFI? I think you said it was a CF spinner, aluminum bends and is easy to see, but CF cracks and you won't see that unless you really look for it. I guess you found out that at 7000 rpm things happen quickly if there's a problem. I had a plastic spinner blow up on a .40 size plane once, it just about ripped the motor out of the plane, and the forces are way less than what we're dealing with on a 50 size plane.

pianori

My Feedback: (2)

Yeah, it happened in about two seconds. By the time I realized what that humming noise was the engines was hanging on to the side.

The spinner was a metal and not a carbon fiber. I think that you might be right as far as the previous prop strike causing some type of damage. It could have caused an internal shear fracture damage to the spinner bolt. What broke was the head of the bolt that held the spinner to the engine shaft. The spinner came off striking the prop and breaking it.

Next time if a prop brakes by striking the deck I will make sure to triple check the spinner, bolts and fire wall. You cannot be too cautious when it comes to making sure that the plane is intact after an incident.

coronabob

My Feedback: (10)

pianori,

Your crashed Extra does not look bad at all. I have put worse back together many times. Since it was your first crash, I am not surprised that you are upset. It's not bad - really. You ought to be very proud for being an exceptional pilot - flying since 14.

davemilw07

Yes, this is true, I've had many bad experiences myself.

You have a LOT to be proud of, so don't get discouraged. You can always rebuild, or buy another (at least that's what I did).........

pianori

My Feedback: (2)

Thank you gentleman you are very kind and encouraging. I can now really connect with someone that has lost his model. Not a good feeling. Any way, I am moving on to a new plane-project. It will probably take me about two weeks to get it all ready. I will upload some of my work here for you to see.
Thanks again for your support.

rctom

Did you check your initial spark timing with a degree wheel yet?

TF

pianori

My Feedback: (2)

Yes I did measure it with a degree wheel and a TDC piston stop. The factory timing was set to 11 to 12 degrees. I ended up using a hose clamp to place the sensor at about 28 degrees. The RPM wend significantly higher. The bunny 23 X 8 now could spin about 6750 RPM, a big difference. Unfortunately I did not get another chance to fine-tune the timing, as you already know the plane wrecked.

I will fine-tune it as soon as I get the new setup ready.
Take care

davemilw07

Did you check the engine over completely, to make sure the crankshaft isn't bent???

pianori

My Feedback: (2)

That is one of my concerns. By turning it does not seem to have bended. However, I am going to have to mount the engine on a block and use a micrometer and spin the crankshaft to make sure. I have not done that yet. I just finished sanding off the edges of the broken fins and cut the bolt off that was screwed to the bended stand off. I will probably check out the shaft later on today with a micrometer. We’ll see what happens.

pianori

My Feedback: (2)

Hey there soarich or anyone else.
I measured with a micrometer the shaft to see if it is bent and I think it is. I am not 100 % sure. The micrometer shows a half of a thousand on the collar (which is nothing), and 8 thousands on the bolt that bolts onto the shaft (I am concern about this one).

I am not sure if the shaft is that much off since there are some grooves on the shaft itself which can be easily the reason why I a getting 8 thousands off (bumping).

I started the engines and it runs fine between 1400 to 3200 rpm and between 3800 and up. It seems that around 3500rpm it has horrible vibrations. I am not sure if that was there before or not. I did not seem to notice the vibrations at 3500 rpm before.

I went to the hardware store and bought an 8mm X 1.25 bolt to replace the bended shaft bolt. I managed to bolt it on, started the engine and the vibration seem to have reduced a little but it is still pretty bad at 3500rpm. I am starting to think that the actual crank shaft inside the engine is bent. Any ideas?

Soarich any similar behavior at 3500 rpm or it is just me?

I’ll call Larry to see what he thinks.
What do you think?

Hughes500E

My Feedback: (16)

started mine for the first time, coming out of an idle, hit heavy vibrations before it went smooth. Second run I had to tighten 3 of the 4 bolts. I assumed it was my test stand!

pianori

My Feedback: (2)

Can you check if you are getting the increased vibrations at around 3200 to 3500 rpm please?

Hughes500E

My Feedback: (16)

sure, should be able to do that tomorrow (Monday) afternoon!

soarrich

My Feedback: (98)

I didn't notice any extra vibs at 3500 rpm. 3500 rpm is where I run it to set the idle, L needle, so I spent a lot of time, well five minutes, at that speed. I'll check tomorrow if my wife is still sick, otherwise it'll have to wait until Tuesday. I'll see if I have any run out tonight though and get back to you.

pianori

My Feedback: (2)

Thanks rich and Hughes500E

soarrich

My Feedback: (98)

On the aluminum propdrive, less than .001. On the unthreaded portion of the bolt .003~4, but that may just be the surface of the bolt. On the threaded portion of the bolt maybe .008, I may just be measuring the roughness of the threads though. This engine is very smooth running, but I'll try to check right at 3500 rpm for you.

pianori

My Feedback: (2)

Hmmm! It seems that I am getting the same measurements as you. Now I have to admit I have always run the engine directly on the plane. This time I run it on a solid 7 X 8 wooden truss. That could also be it. I’m not sure. I would be very interested in hearing how does yours behave around 3200 to 3600 RPM.

Now that I think of it I remember when it was on the plane at one particular throttle setting the wings would shake more in compare to other throttle settings, but past that throttle or below it would go away. So it could be that the harmonics of the engine are tuned to be around this range and I did not notice this behavior before because it was absorbed by the airframe. It could be that now that it is on a solid piece of wood I am feeling the vibrations more.

Just a thought. Let me know what you find out.

Thanks

ljones5000

My Feedback: (2)

Sorry about your misfortune. I notice you are running an "E" plug. I had purchased one of these plugs but never flew with it because I realized no R in the name. I had always heard that the plug should have an R in the ID to indicate "resistor", otherwise it could cause RF interference.

Not saying that was the root of your RF interference but it got me thinking.

soarrich

My Feedback: (98)

FWIW Ralph Cunningham on several occasions has written that resistor plugs are not needed on these ignitions, they are fully shielded so it doesn't matter.