Look at the prop in his model!! Two different props (No 4-blade prop!!)
Piotr Åšwiderek
www.swiderek-f3a.prv.pl

cool.....

Interesting! Any chance you have more informations on the setup? Looks like someone's trying to deal with the huge diameters ( 23", 24" ) whe see nowadays on some setups...

Regards,
-Fabrizio

Is it just me, or are the 2 props not at 90deg to each other?

I think they are not at 90 degrees.......................I would like to see the fly report..................

What are the two prop. sizes?

Steve

I don't know what props he used. In my opinion it's 2 props, not at 90 degrees. He used Hacker engine.

Piotr Åšwiderek
www.swiderek-f3a.prv.pl

Todd Blose had one of these on his electric Genesis at Nederland. It's not two props ,
it's one custom made electric prop with 4 blades. Sorry, didn't notice the size and pitch.
The blades are NOT at 90 deg to each other. Todd said it is very quiet.

tommy s

Anyone know why this is so? Intuitively (to me at least) it doesn't seem like it would be as efficient as a regular 4 blader. Clearly it works though.

James

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The tail rotor blades on the AH-64 Apache are offset at less than 90 degrees to lower the noise. . .
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Here is a picture of Todd Blose's X electric props. As I recall they were one 18" prop and one 17" prop. Sorry I don't have the pitch.

He had not flow the plane when I took the picture.

Steve

I talked directly with Chip at the May Vegas pattern contest, though now I can't remember the prop sizes.........

Its 2 different props with a small piece of balsa (or plywood) between them and glued together. He is using the 4blade mainly to stay away from the large size of the 2 blade. He didn't put them at 90 degrees for the same reason the Helo's don't.

Here's my problem with it, you have engineers that actually put the props on the Helo's at specific angles with lots of models and testing. Chip just placed his at those angles and hoped for the best, there is no way to know if at that specific angle its performing at optimum ranges.




------------as far as performance........I saw 2 Genesis electrics fly that day. They both looked fine, no problems at all. Did chip's look better? Yes and no. He flew better but I don't think the prop had much to do with his smooth lines. Infact he had a midair and lost most of a wing, then borrowed a wing from another Genesis and finsihed his round. He flew just fine like that. He can fly......no matter what, basically.

And tail rotor blades on helicopters run at a constant rpm, only varying pitch for thrust changes. IMO rpm will be a large determining factor on what the separation of the blades should be.

I wasn't there but the comments I heard from friends who were at the meet was that it did not have the power of the 2 blade prop equipped electric Genesis. It was very quiet though.

How the heck do you balance it?
Greg

the inner prop was larger than the outer......he balanced both first. I don't recall him saying that he balanced his at all after they were put together.

His plane was extremely quiet.

I'm thinking it might be time to resurrect Pretteners Variopitch props.

Or failing that, Contra rotating props?

Dont laugh, have you seen the latest axi "Dual 5330" with twin contra rotating outrunners, could really change the way we trim pattern models.
Looks kinda pricey though!!!

Just surfin and thought I would try to help better explain y the X prop. I did see this on wings about 15 years ago, and always wanted to try it. I was tempted to try it before the last worlds after test flying the plane Jason flew but we had no time. That was a fairly small plane and while Jason flew it awesome, the big disk was definately not a plus. I only flew it one time and that was for about 4 min on the first flight. (The reason I had the honor was because, Jason being severely allergic to CA and due to all the mods we had to make to it,could of easily been blind folded by dental floss and was in no condition to do anything)

Anyway there was not the selection of props then that there is today, and the batteries were nowhere near what they are now so I am sure it would not of worked. That brings us to this year and when I teamed with Hacker and Aeromodel , I immediatly saw the potential for this to work. The way we went about it was more a common sense approach, then a scientific one. I know how props work for the most part and to me this just seemed like the way to minimize the three drawbacks IMO came with the move to electics.
1. Big disk, little plane (Bad)
2. Big disk lots of prop noise noise (Bad)
3. Downline breaking like a two stroke on a pipe. (---) <G>

Anyway the smaller disk is definately better for noise, in fact its erie at times, but that is a good thing.
It is also much better for spins and snaps making both direction an option at all times, and
Finally the down line speeds are far slower due to the extra blades.

Now for the negatives
1. Less power no doubt about it, however Its still more then enough for all wind and temp. combinationations, but you have to move the trottle stick in order to get results. I fly at full some days when the temperature here (or in Vegas) is well over 100F and we have 15-25 MPH winds. I don't care if I put 4200mah back in or 3200mah after my flight because its not costing me anymore to do so, just a little time.

Anyway, those were my objectives and it has solved them, along with its a much smoother throttle response as well as being a half ounce lighter then a two blade.

Chip

BTW I came up with the two motor counter rotating deal last year and mentioned to HL it was my goal to have it working by the worlds. Looks like the AXI boys listend. <LOL>

The funny thing is, I listened to a guy tell my dad about 20 years ago about how he figured out how to actually do this same thing with a couple of geared OS 90's for the 82(or84) TOC. He was just a little ahead of his time and couldn't get it quite get it perfected so he went back to the single big prop for the contest. I am sure he was in the Top 5 that time. Can anyone name that pilot.

Chip, was it Dean Koger? I remember him experimenting with geared drive combinations.

Ray

Chip, can you elaborate on why is large prop disc bad?

Thanks,

David Kyjovsky

How are things out at Fort HoochieCoochie ? LOL

Nope. but they did both live in the same state at that time.

Haven't been on post for almost two years, but I think its still there. LOL

Chip

The larger the disk is, due to the fact it only spins one way, increases the effects of three things that are not condusive to a good flying patteren plane. This type of planes sole purpose in life, is to make, long, striaight lines, with combinations of 1/4 loops, and half rolls in everyone, and I feel most will agree.

However the larger the prop is means more torque is created, along with increasing P-factor and spiraling slipstream. Those 3 forces that we all have to deal with are the reason I laugh when I here someone complain about a 1/4 inch bow in a fuse or wing. Or see some of the contraptions people dream up to make sure the right elev goes down the same number of thousandths as the left one. IMO A plane set up totally equal on everything along with being perfectly straight would not be a very tru feeling model due to those three things. I have set up airplanes with every thing from the clothes pin degree meters to laser levels and everything in betwwen in the past 6 months, and the one that has always provided the best flying plane for me, from the get go, was a steel ruler measuring in 1/32's of an inch. The reason it works so well for me is becuase, one day a few years ago I realized there are a few neverchanging things that all that are going to be in every single prop plane there is, that has just one prop spinning the same direction all the time. Once that became apparent my setup time and trimming process shrunk dramatically and I was very frtunate to not have to switch radio brands in order for that to happen<G>

I don't have time to go into much detail but if you start out with these things already addressed before your first flight on a new plane you will be way ahead.

1. All planes will roll faster left the right due to torque, so make sure you set your ailerons in the TX 5% less to the left from the start

2. Whether you use right thrust or not due to spiraling slip stream you will always need a throttle to rud mix to fly in a straight at varing throttle settings. Standard is about 3% and the direction is thrust dependant. I use very little enginee thrust so mine is always adding right rudder as I increas the power.

3. I have never in my life had a pattern plane that took 0 aileron Dif. They have all taken a degree more up then down, so dial it in at the house and avoid guessing when you get there.

There are some other little things like thottle to Elev. for straight downlines which all planes need, and 5% less travel down then up on the elevators, but I am beat and cannot get real indeapth as to why.

Anyway sorry to ramble but all of this stuff is directly affected by the size of that disc, and when I say affected I mean in a bad way. The only positve is downline speed is a little slower as a norn, but there are several ways to make that happen .

good luck and hope some of this might help a few of you with your future projects.

Chip

You get up as early as I do -
How about lateral balance?
Ever bother?
I don't.
But on my little electrics -I have fooled a bit with vertical balance -that is -balance the plane such that it is neutral if held level by the prop hub - horizontally.
Ever tried that?
You weren't referring to dear ol Dave were you?