wolf - I have run almost every 50-cc class engine out there but two... and ALL of them have a natural "resonance" point in their rpm range. I think it has to do with the counterweight/con rod design, piston mass, etc. Just a click below, or a couple clicks above, and it seems to go away. Mine all seem to be around 3000-3100 rpm or thereabouts. When I realized that it was just 'the way it is', I quit being concerned.

Glow engines also have a similar resonance.

I don't know enough to explain the "why" very well, but they do...

hey guys thanks alot for all the info, i have a vess 22x8 on the way

Wolf, Did you balance the hub of your prop?

wow its late i mean B kinda looks like an 8

I have run less than 1 gallon tyhrough the engine at 32:1. I have also seen this effect with glow engines so I figured this "resonance effect" was probably par for the course. I can't tell you how much time I spent trying to tinker that last bit of vibration out of this engine.

I suspect when I go to the synthetic mixture and re tune the carb I might be able to smooth a little more vibration out of it.

I just didn't want to throw it up in the air and have it go critical mass on me. Oh yeah, It's going into the Hanger 9 Extra 260 / 27%. 78" span, I hope to bring it in around 14.5 Lbs..... El Rocket Sleddo!

Thanks, Ken

Yeah, I checked it twice.

I used a Vess 22 B. Seems like a good prop. I had to sand a tip but only slightly. It holds at 11 and 2 positions so I think the hub is good although I didn't have to weight it.

I'll probably check it once more before the maiden flight.

Wolf, I don't like to sand my props, try a can of clear spray laq. (can't spell it but hope you get the idea) put the prop on the balancer and spray the up side. easy does it little goes a long way. If your not careful you will be spraying the other side trying to get it back.

I use thick super glue and a plastic bag on my finger to spread it out on the tip of the blade. It works great.

That is a great idea Ed, we have been doing that for about a year now and it works great but like you said it dosen't take much.
Tom

What are you people using for break in props?
I bought my DL 50 from DL USA and the prop he included for break in was a Vess 22A.
From what I have been reading that may not load the engine enough.
What do you think?
It will be going into a TOC Yak 54 30%.

Greg

I plan to use a Menz 22X8, the one that broke DA50 with.

OldRookie - Vess 22A should be a GREAT break in prop. I've talked with Bob K., and he swears that is "the" prop for letting the fresh engine spool up; and that is really valuable, I think. I wish we had better weather so I could test my Vess' out. I'd bet you will love that combo....

That will be great for break in. Just watch your throttle, keep it in check. Depending on your altitude it may spin that prop over 7500rpm static. The idea of a break in prop is to keep engine load low but not to go so small that the engine over revs.

Scott

to wolf65,
I have my DL on a H9 260 I think it was 14.6lbs with half a tank of fuel last time I weighed it. I'm just starting to hover some and it adds new meaning to "punching out" of a hover. I have a TBM 23x8 on it now, so it's a dog, but if anyone wants to vertical drag race, I can throw the JXF 22x8 back on and there isn't much that would out pull it.

aerobob,

Thanks for the reply. That puts my mind at ease. With the price of these props I would hate to get one that is not of much use.

Thanks again for your replies,
Greg

Scott..... haven't seen you much lately..... enjoying the ice, are we??? [:'(]

I'm running a Vess 23A at 7400rpm so be careful with the 22.

Hly Shmokes, AL..... pretty soon someone's gonna ask you what oil you use to get all that power..... and what tach you own so theirs can be as good....

LMAO I ain't vouching for the tach but this thing screams. I am at sea level nearly, four inches below last week, so that may help. AND... I am not answering any more OIL questions!!![sm=bananahead.gif][sm=bananahead.gif][sm=bananahead.gif][sm=bananahead.gif][sm=bananahead.gif][sm=bananahead.gif] It's 50:1 Belray H1R, that's it!!! LOL

OMG !!!!!!!!!
NOW you've done it..... get the popcorn! Somebody grab a beer!!!!!!! This is gonna be good....

So WHICH oil produced this incredbile (sp. intentional) power??? Was it REALLY Bel Ray??? OR ????

You're really evil!!! You know that???? Don't you dare start. If I see one more oil thread or one more "Is BME Still in Bussiness" thread I'm gonna scream!!! Use baby oil if ya want and NO You Ain't Getting No More BME Parts!!! The guy ain't answered a call or e-mail in 3 months!!! Catch on!![sm=48_48.gif][sm=48_48.gif][sm=48_48.gif][sm=48_48.gif]

Hmm.... Baby oil = mineral oil.
Wonder if it would make the gas smell good?

(Ain't goin' down the BME road, neither. Don't want this thread locked up)

I bet the DL would run quite well on mineral oil....

And now you can spend the next three days explaining why!!! LOL Just saw your local news, you're getting 6 inches of snow day after tomorrow. Better put that DL on skis!!!

I haven't figured ou where you do all that flying in the weather you are having. I would imagine that DL would get a little noisey indoors, probably no louder than a teenager with a good gheto blaster though. Weather has been so good here I have run out of clean T shirts. [sm=shades_smile.gif]

ed - THAT is just plain RUDE!!!!!!!! [:'(] To tell us about your "laundry issues" and blame it on a DL, to boot!!!
I think we should all meet up in Irving, TX and have Bob K. show us what it is all about....at least it would be an excuse to escape winter for a while....

Aerobob, Like the idea about Texas. Lets call it a DL convention, lots of girls in bathing suits, good flying weather. If it gets any better than that, its only because I can find a way to write it off on my taxes. Tom at Valley View could take it off as a business trip.