RE: Extreme Flight 87" Yak 54 - Build & Fly
 

When I ordered my 50 and pipe from DA i was planning to get the mejzlik 23x8 but I asked them
what do they recommend for the particular plane and if there was a break in prop that will be good also for later.

MSC 23x8, Kevin said.

I have great experience with the msc props on my bme 50 and da 100 so it was an easy decision.
I got 2.

Stratos.-

RE: Extreme Flight 87" Yak 54 - Build & Fly
 

Mike,

Keep in mind too your altitude... (what is yours anyway)...

Higher altitudes can take (and require) a bigger prop to jeep the RPM's down

23x8 would be a good choice for high altitude...

Ilove DA... but you can talk to 10 different salesguys and get 10 different prop suggestions from them... At the Toledo show last year they told me the best overall prop was a 22x8 or 22x10.. .;)

There seems to be quite a few people who just simply go out and git 'er done from the get go... no special attention to keeping the throttle down for a while... even jumping straight to the 3D prop of choice... just rely on the ashless oil to break in...

I'm guilty of the throttle... I mean there AIN'T no way I'm not gonna wring this Yak out on the first flight on my new DA... but I'll keep the prop to 22x8 and of course run the 32:1 Lawnboy Ashless...

Then again.. I am running the pipe.. maybe I should jump to 23x8... :)

RE: Extreme Flight 87" Yak 54 - Build & Fly
 

OK, I am borderline thoroughly confused..<g> I'm at around 1000 ft altitude, and it never gets hot here...if it goes over 80 in the summer, its a big deal.... Sounds like a 23x8 would be best all around? How many flights is it gonna take to break it in??? I used the lawnboy ashless on my BME 100, plane didn't last 40 flights, and I just switched to amsoil for the last gallon I mixed....

I think they are backorderd on the 23x8 props. not a big deal, I'll be on vacation for a few weeks, no hurry to get this stuff...

So, unless I get persuaded, I will go with 23x8 menz......


Nobody grabbed the 3 blade prop question.......

Thanks, Mike

RE: Extreme Flight 87" Yak 54 - Build & Fly
 

You'll be great with the 23x8... 4-6 gallons is what is recommended... and with as much fun we are all oging to have with these Yaks... that's about 3 days of flying right? :)


I've never run a 3 blade... I think they are very sexy looking, but the whole "less power, less efficient" thing kept me at bay...

But I sure do like the looks of Chris's prototype pics with the 3 blade... I think it was a 21x10... Chris could confirm that...

RE: Extreme Flight 87" Yak 54 - Build & Fly
 

I don't want to get into a whole discussion about breakin, but....It's not what a lot of people think.
The key to a good breakin is to produce as much friction as possible without overheating the engine. Thats why your told to use a pure ashless oil with no additives that will inhibit friction or wear. Yes your looking for ring and cyllinder wear to occure as quicly as possible without, scoring the rings, piston or cyllinder. (before the little micro groves fill in with carbon and prevent the breakin) In simple terms, The rings are actually wearing down to match the cyllinder perfectly.

If you can or could keep the engine cool enough, full power would be the best throttle setting. Unfortunatly it's usually not possible on a air cooled engine. (sometimes it is, if you live in the north and have cold weather). High RPM's and high airspeed for cooling are the key to sucess. The most important time of the breakin in the first tank of gas. Failure to acheive adaquate preasure on the rings and cyllinder during this time may cause an engine to never breakin correctly, or take a long time. In the case of watercooled engines where temprature is more of a constant, many of the 2 stroke racers start their freshly rebuilt engine and use 100% power setting immediatly. The work "breakin" isn't even used. The first time the engine is run may very well be at the race itself. In this particular instance I'm refering to snowmobile racing.

run it like you stole it, but keep it cool

JOhn

RE: Extreme Flight 87" Yak 54 - Build & Fly
 

Good info John... make a lot of sense...

RE: Extreme Flight 87" Yak 54 - Build & Fly
 

Makes sense John, my dad built and raced dragsters when I was young, he always believed that if you didn't break it in hard, it would never run hard...even with new cars, he would slam them the first day....

So, if I have the cool enough temps, on the first tank of gas, I should run it hard???? I believe I idled and fussed around on the BME......didnt run it up much intentionally....

THanks, Mike

RE: Extreme Flight 87" Yak 54 - Build & Fly
 

Idleing a new engine is not good. (except for bringing it up to operating temp, never throttle a cold engine) The trick is to use as much power as possible without overheating. Thats where it gets tricky if you want things perfect. If you don't have a way to measure temp. It's probably best to vary your power setting. Full power, then back to half, full power and back to half (allowing it to cool)start with short intervals at first, maybe 10 to 15 seconds, and increase the intervals with each tank of fuel for the first gallon, or as long as the manufacturer recomends and depending on the type of flying your going to do
john

p.s. The difference between a perfect breakin and a just good breakin is probably not noticable to the average person. The manufacturer will always recomend a conservative breakin, as they don't want to fix a scorched engine at their expense.

RE: Extreme Flight 87" Yak 54 - Build & Fly
 

I have an infra red temp gun....big electric helis get lots of hot components.... Anyone know the ideal operating temp for da50? And also the temp that you don't want it to get too...:D Then I could get it to the right temp and maintain it by temp.....sounds too easy<g>


Mike

RE: Extreme Flight 87" Yak 54 - Build & Fly
 

Around 170-180 degrees I think... much beyond that and you're getting a little too warm... 200+ and you have a problem you need to look into...

RE: Extreme Flight 87" Yak 54 - Build & Fly
 

you sure Dave, that sounds pretty cool

john

RE: Extreme Flight 87" Yak 54 - Build & Fly
 

I'm not sure of anything... except I need the snow to melt off my field. :)

Honestly... I just got into the whole laser themo probe thing last summer... And asking ZDZ about temps...

I just checked back to the e-mails and he stated 190-230 MAX... SO I stand corrected...

Seems to me I've recorded the 170-180 tmeps right after a flight and before the engine builds up over 200.

The heat balloons shortly after killing the engine so it's important to get the reading as soon as the prop has stopped moving as possible... check it a few times and you'll see it run up another 20 degrees or so...

Maybe it was 190-200 and it balloned to 215...

I dunno... that was before yesterday...

Dick Hanson... you still lurking? You got the goods on CHT right?

RE: Extreme Flight 87" Yak 54 - Build & Fly
 

Based on other engine experience I would say running these at 200 degrees is no problem. I'd start getting concerned at anything over 225. I really don't see damage being done until over 250 degrees. But I don't build or make engine, I just run 'em!

RE: Extreme Flight 87" Yak 54 - Build & Fly
 

Isn't that backwards ? All engines (especially normally aspirated) will produce less Horsepower as the altitude increases (air pressure decreases and becomes less dense) I think I know where you're coming from, in that the prop will spin faster in the thinner air, with less resistance, but keep in mind the engine is also developing less power, therefore will not turn it as fast. Even for those that don't understand the reasoning, I think we can all agree that as a rule of thumb, the higher you go, the less power you have, so logic would dictate a smaller prop would be required to maintain the same RPMs.

RE: Extreme Flight 87" Yak 54 - Build & Fly
 

Talk about a can of worms! This thread is getting better and better.

Just to shed some light on the "other" viewpoint. Every Corvette and Porsche come with Mobil 1 synthetic as the factory fill oil, the same 100% synthetic with all the "additives" to prevent wear that enthusiasts buy to "protect" their beloved engines, so how do they ever break in?

Another point, many high performance cars, (the BMW M3) (SVT Cobra) have recommended RPM limits for certain mileage intervals, I think we all agree never to "dog it" when it's cold, but even fully warmed up, many manufacturers recommend these limits, and No full throttle (regardless of load) for 500 miles or so. (can't remember off the top of my head) Anyway, as with everything there are two drastically different schools of thought on this.

RE: Extreme Flight 87" Yak 54 - Build & Fly
 

I seem to remember reading that saws etc. run around 300 with no problem. I had some kart racing buddies that told me they didn't mind running at 300+.

Most of my engines on the test stand running WOT are well over 200. I've also been told by a racer/builder that 300 is not cooking yet.

I always baffle and have appropriate inlet and outlet. No sense taking any chances with the cost of these engines.

Don't want to start anything here, just relating what i've been told/seen.

Here is a good thread to read concerning temps, it will open your eyes
http://www.rcuniverse.com/forum/m_96.../tm.htm#964307

RE: Extreme Flight 87" Yak 54 - Build & Fly
 

Heck...keep it up... Im Lernin somtin :)

RE: Extreme Flight 87" Yak 54 - Build & Fly
 

My mistake oops

RE: Extreme Flight 87" Yak 54 - Build & Fly
 

same here. Us electric guys gotta hang together. BTW, aren't you the same guy RCG that's doing the review on Stella?

RE: Extreme Flight 87" Yak 54 - Build & Fly
 

Cad,
Tram is doing that one. Couldnt have choosen a better man for the job. :)

-Mike

RE: Extreme Flight 87" Yak 54 - Build & Fly
 

Mike,

Okay, he's doing the pitts too. I thought you were the same guy. Tram's coming up soon to pick up a plane he got from me. I'll be sure to rub it in that my Stella is ready to fly first. He'll probably beat me on the pitts.

When I get the yak going we'll all have to hook up some weekend with Mike Hall and Jeff and some others and have a "impromptu" fly-in.

RE: Extreme Flight 87" Yak 54 - Build & Fly
 

There are broken in on a dyno first, then installed in the chassis... I know for a fact that Porsche bench runs every engine before it's installed in a chassis...

We always used to break-in race engines on the dyno using 10W-20 petroleum based oil to seat the rings and bearings... The lighter the oil, the faster the break-in period... On drag motors we found that once the engine is fired, we would bring it to operating temperature as fast a possible (210 degrees) and then put a load on it to quickly seat the rings and bearings... Twenty minutes of this at varying RPMs was usually fast enough to get the job done... Then we'd change the oil to 100% Amsoil and put the engine in the race car...

A new engine will NEVER seat the rings & bearings correctly running strictly on synthetic oil... Doesn't matter if it's a chainsaw engine or a passenger car engine ... Mucho lost horsepower and it will always blow oil around the rings...

RE: Extreme Flight 87" Yak 54 - Build & Fly
 

That we can do :). Ill bring my 1/5 scale Pitts too :D.

-Mike

RE: Extreme Flight 87" Yak 54 - Build & Fly
 

Oh yeah, you've got the "big" one :)

RE: Extreme Flight 87" Yak 54 - Build & Fly
 

I got my Da today . stock muffler, igition, Tru -turn. spinner. Prop drill jig.

But, I got a 22 x 8 Mejzlik Carbon fiber Prop with it. It was used and has 1 1/2 gallon thru it. It looks pristine.

That 22 x8 Cf prop is just not the right prop, huh? It stinks, 'cus this prop is beautiful . I do not have any other use for it, but it shore iz Purty.

Flying with Wayne and Drew tomorrow morning, I am bringing my 101" Big Stik , and a H9 Twist w.50sx and pipe.

My Yak 68 is in Yak heaven:(:(:(