This is frustrating me/others.???

You are asking for help , but doubting the advice.

1. Forget your inane wanting to try different fuel. you are wasting your money as nitro is not the issue. Thousands of people use it.
2. Fix your carby screw. - Otherwise OS would make the engine like this. It is a highly potential area of air leak!!!! =Leaning the engine= hot =current need for needle adjustment setting
3.. You are overpropped!!!!!!
If you dont try these things dont ask or help!

Phew ...now i feel better! hahah

Ok, you blew off some of the pressure. It would have been very quick if I could run the engine everyday and try out the suggestions. Unfortunately, only over the weekend

Ameyam

Ok, went to the field today. Checking 5 props is a bit of an effort. Installed the prop, tuned by ear 1/4th turn back from peak, ran for about 30-45 seconds each time and then took the readings. There was no one to help me, so it was a bit awkward because everything shakes including my hands, and I am not able to perceive the tone change for last 10% tuning, so results may not be 100% accurate. Got the following results with a tachometer and infrared gauge

13x7APC- RPM 11200 Temp on cyl head 100Deg C

14x4MAS- RPM 13100 Temp on cyl head 103Deg C

14x6MAS- RPM 10400 Temp on cyl head 110Deg C

14x8MAS- RPM 8400 Temp on cyl head 104Deg C

13x6MAS S2- RPM 11500 Temp on cyl head 122Deg C

The readings are in chronological order. Note that the temperatures drift a bit. This may be because I tested one prop after other only a couple of minutes apart- about the time it takes to take off one and install the other without spinner. Also, I initially got a 127 Deg C reading on the 14x6 but after the 14x8 gave me a lower reading, I tried the 14x6 again and got a lower reading. Also, each time I noticed that the engine have very soft compression after I had just run it for a minute, no matter what the prop

Note all of that was with the 10% nitro mix. It took an hour for me to do all of that in the 38 Deg C heat and I was too fed up at the end of it. Also, so many people on the field and not one person came to help me which was extremely disheartening. All those people who would regularly help me wer not able to make it today.

Nonetheless, I did it, then realised that I need to fly anyway, now that I was on the field. Still had the 13x6 on it at the end. So, just to check if that helped, I pumped all the 10% nitro fuel out and put in the plain synthetic fuel I had blended the night before. With that I tested the engine, tuned as before and took-off. Engine remained operational the entire flight. Did seem to loose some power marginlly when vertical but that could be due to the tuning (like I said I cant perceive the last 10% of tuning). After I landed and taxied in, I took a temperature reading immediately after I cut the throttle and that was 84 Deg C. Subsequently, I installed the 13x7 again and flew twice more. In the 3rd flight I tried hovering. Since the engine was 1/2 turns rich from peak (I didnt have a helper to hold her vertical so I could tune for hovering so I set it 1/2 turn out from peak), the airplane responded a bit late to throttle and (by then) there was a stiff sea breeze that kept pushing it around. I noticed that it would start to wing rock which I couldnt correct with any control and when I added throttle at 60%-70%, she would simply climb. When I landed, I put my finger on the crankcase and was able too keep it there without too much discomfort. Remember, touch down and taxi was about a minute.
Phew that was a lot of typing but I described everything that happened

Now my inferences

1) There was something wrong with the 10% nitro fuel. It could either be too much nitro for the conditions or hydrolysed methanol or something else

2) The 13x7 is not suitable for hovering, need to put the 14x6 or 14x4. Leaning towards the 14x6 for better hybrid performance and because the 14x4 gave a 13000+ rpm

Any inferences you can draw?

Regardless, I will be ordering a DLE20 and opening up a Phoenix Extra 330S for that engine (or the 120ax) very soon

Ameyam

why the phoenix 330? If you want a serious 3D Extra, check out the choices from 3dhobbyshop or Extreme Flight.

Also, you must have a super .75ax, because my 95ax wouldn't turn a 14x6 much past 9k rpm. Either that or my tachometer is off. It could also be the mile high altitude where I live.

All of your readings are far too cold, so you are taking them at the wrong location or under the wrong conditions.

- You must take the readings with the engine running full throttle.

- You must take the readings after the engine has run at full throttle for at least 1-2 minutes

- You must take the readings at the hottest part of the engine. Typically close to the exhaust or around the glow plug.


Note that you are only achieving somewhat normal RPM numbers with the 14x4MAS prop...

Roughtly speaking a 14x4 is about the equivalent of a 13x5 or a 12x6.... and amazingly (not) the latter is pretty close to the 12x7 I told you to try originally!

Do you understand the relationship between diameter and pitch when you move up and down sizes?

Roughtly speaking for each diameter size you go UP, you must reduce the pitch by one... ( this is not exact, so those who know better please don't point it out... )

-

These are your own observed results ( I only used the same props as this is more meaningful ).

13x6mas S2 = 65 mph pitch speed, 1.86 HP, 10.69 lbs static thrust
14x4mas = 49 mph pitch speed, 2.46 HP, 18.66 lbs static thrust
14x6mas = 59 mph pitch speed, 1.85 HP, 11.76 lbs static thrust
14x8mas = 63 mph pitch speed, 1.32 HP, 7.67 lbs static thrust

So the 14x4mas is putting the "correct" load on the motor... adjusting to try to put the same load using a different diameter... puts you back to a 13x5, or a 12x6 prop!!!

Exactly what everyone has been telling you all along!



yachty: I feel your pain!!!

Opjose,

See, I am not contradicting your suggestions. My main problem was the overheating engine, or to put in another way, the reduction in compression and black oil when hot. I dont seem to be having that problem with this new fuel (though it isint confirmed yet).

I asked a 3D expert on my field regarding the hover issue and he also recommended the 14x4. But there wasnt enough time to test that prop out on the new fuel. May be I can check both temperature and RPM (after running for 2 minutes, that was the original plan but the heat summer probably got to me) for that next Sunday.

DenverJayhawk,

thats because I have the Phoenix Extra. The international prices for the 3DHS Extra is $400+ with shipping and customs extra and EF dont ship to India through any route. The I got the Phoenix Extra for just $115 landed as I bought it at my LHS scratch-&-dent. In this respect, we have to live with what we have

Ameyam

theirs nothing wrong with running that engine at 13000+ rpm, heck theirs nothing wrong with running it at 16000 rpm
the 14x4 would be the best 3d prop, it revs up faster which would help pull you out of trouble

Ok, that settles it. I will put in the 14x4 this evening and risk taking a temperature reading after running at WOT for 2 minutes in my neighbourhood. If I have any any issues, I will report

Ameyam

Just skip the temperature reading, it doesn't tell you anything anyway (which is also evident from you readings). Just go by the rpm and how well it holds the rpm and needle settings. The 14x4 sounds like a good match based on your rpm numbers. I don't understand why there would be anything wrong with the 10% fuel, or why you did all the testing on the 10% fuel and then flew with 0%?

Some engines actually run colder with a bit of nitro in the fuel, but they also need to have the correct prop.

Hi!
Yes skip the temperature readings! Being a racer (Pylonracing ) I can assure you that no racer meassure the head temperature ...we set our engines by ear!
And that's the way all sport fliers should do too!

You must understand that most engines like some nitro. 5-10% nitro is all it takes to a have a all engines run just fine.
Running your engine on 0% nitro is no good. That makes it run hotter due to a much peakier high speed setting (Means it is more likely that the engine goes lean due to problems setting it right).

Ofcoarse you can use 14x8 prop on your engine! But remember doing so means you have to set the engine right (means setting it ritch so it will not overheat). But why use a 14x8 prop on a .75 engine??? A more suitable prop for sport flying is a 13x6,14x4 or 14x5N APC.
You have to choose the right prop for each airplane! That's very important!
Best props today are APC, Graupner Cam-prop or RAM. Avoid MA white tips props!!!

And do fix that carb! Silicon isn't the right way to solve the leaking carb problem!
Put in a larger screw in that hole securing the carb! I suspect it's a 3,5mm screw now. Use a 4mm screw instead!

If you don't mind it behaving like a overweight hog...

e.g.

14x8 mas = 63 mph pitch speed, 1.32 HP, 7.67 lbs static thrust

You would get just as much power from a .32 glow engine running a 9x6 prop!



As for the temperature sensor... under normal circumstances I agree there is no need for a temp gun/sensor at all... ( except in a pusher arrangement... they are quite useful for that... )

Unfortunately ameyam insisted on using the wrong prop sizes, in spite of people telling him to do otherwise.
Then as a result he reported his engine effectively overheating, but he did not nor would not attribute this to the overly large props he was using.

So the temp gun/sensor is more to prove the point that he is using the wrong prop...

No problems. Right now I am waiting for the Tower monthly discount email to place the order for the props you mentioned. I will also be getting a tach, bubble-less clunk, flexitank etc. Since I have had ear problems when younger, I may not be able to hear the engine well enough to set it by ear (or whatever that is), so a tach may help.

I decided not to open up my newer airplane for now. Our season ends in June due to the monsoon and there are, may be, four weekends left, so no point in trying to learn a new airplane just yet. I will set it up in October when proper flying restarts (we take chances and fly during the monsoon when there is no rain with our cheap trainers). It will also allow me to save up the $$ for the new AW Yak 120 QB.

Ameyam

A thing about the Aeroworks YAK 120. Last year one of my friends picked one up, AW was telling people these planes were perfect with the DLE 30cc gas engine, They Are!!! Size wise it's not a very big plane, it's span is 4 inches longer then the old 60 size Extras. As far as ARFs go this is one of the better ones I have seen. Only minor mods needed to the LG block. Very easy to assemble and some very good hardware. I like everything about this little plane except the price but if you want an AW plane they give you some pretty good stuff with the plane. They also over rate the required servos but they stating the best you can get for dead on 3-D. The big servos are not needed at all, this is a very light weight plane. Very stable in the air. I'm not a 3-D pilot but even an old IMAC pilot can make this one hover!! Over priced but a very high quality ARF.

I know and understand that they are priced high but the quality is also better that what I have locally. And the 62" without spinner length is just about what I can carry around currently.

Graybeard, are you suggesting to skip the dle20 and go for the 30 instead? I was going to put the 20 on this airplane unless you suggest otherwise. Then I will put the 120 on my Extra and or / Phoenix Yak when I decide to build those

Ameyam

When my buddy bought his AW YAK QB .90-120 AW told him to use the 30, not me. I have a couple of nice 1.20 four strokes on hand I would have loaned him for this plane but he really wanted to go gas and break away from Glow. He got with a couple of local 3-D giant scale guys and bought all the over the top good equipment for this plane and the DLE 30. I thought it mite be too much engine for a light air frame. I was wrong, it's a perfect combo. It has been a year and several other airplanes so I have forgot a lot about it but as I recall I gave him some angle stock and he reinforced the fire wall and the landing gear blocks. That was about it for doing anything to the air frame. The plane is a light weight but it was designed very strong. When he handed the controls over to a couple of the local 3-D pilots it was amazing to see what this little plane could do. I'm not saying what engine to use but this is what AW said to use and it has worked out really well. Until one of the 3-D pilots was teaching my buddy the stalled landing and he stalled it just a bit too high. The pancake landing resulted in a banged up cowl and the LG caved into the wing. A couple days of reapir work and it was flying again. Very good plane and engine combo.