Help - Which Prop?

[rehler]

I hope some of you are familiar with the two props that I am considering and can let me know what you know about them. I need to decide which one to buy to use with my new Rotax 912S engine.

1. Arplast - ECO PROP - as used on the Magni Gyros

2. DUC Prop http://www.duc-helices.com/technique/windspoon.htm

http://www.microlightsport.co.uk/Catalogue/New/DUCPROPELLER.htm

Both are expensive. The DUC prop is supposed to be very quiet and efficient. The Arplast prop is beautiful and has a reputation for high quality. I like quiet and efficiency. And I like beauty and high quality.

Which is best for my gyro?

[GyroRon]

What is wrong with a good ole warp drive? You know all these other props may be slightly better performance, and less noise..... BUT....... they all cost way WAY more money and will not take the abuse the warp will. I have had major pieces of my gyro go through the warp drive on my former Dominator and the prop got chipped but not destroyed. Easy to fix the chips with some baking soda and superglue.

[rehler]

Steven,

Thanks for your reply. As far as the PowerFin prop is concerned, I had a bad experience with one.

I have a 65" Sport Prop and wanted more thrust, so I bought a 68" PowerFin prop (larger diameter). After trying different pitch settings I found the the thrust produced by the PowerFin was noticeable less than the smaller 65" Sport Prop. Also, the PowerFin was really noisy - very loud to a point of being uncomfortable flying it. I guess to be fair that I was spoiled by the extremely quiet Sport Prop which has the curved or curled prop tips.

My PowerFin prop was destroyed by a small piece of metal flying through it - cut of one blade completely (see my web site for a photo). When I put my old Sport Prop back on it was beautiful. More thrust and quiet.

As a result, I do not like PowerFin props, even if they are much less expensive.

[rehler]

GyroRon,

The Warp Drive prop is good.

My first gyro (Air Command) had a ground adjustable wood prop. After repairing and rebalancing it way too often I went to a Warp Drive (back then it was named "Ivo Prop" - before Ivo created his new prop). I loved it. It was strong and lasted for many years and over 500 hours, and it gave better thrust than the wood prop.

When I bought my Verner engine I got a good deal on the Sport Prop. It was much quieter and also much lighter, which I read was better on the reduction drive. I like the light prop better than the heavy Warp Drive prop. I also believe from what I have read and heard that the thrust from a Warp Drive is about the same as the PowerFin, and my experience with the PowerFin (see above post) is not good.

So, I THINK that I will find either the Arplast or the DUC Prop to be a better choice. I am really looking for the very best I can buy, and am willing to pay more as seems to be needed.

[CLS447]

Ken, do you mean that Ivo & Warp Drive were one at some time? I always thought your gyro was a first class creation; now with 912 power why not get the best prop. Not to mention those new blades that you are gonna LOVE! Have you considered a Prince Prop? I'd be ordering one in red right now if I wasn't so darn broke! Keep up the great work! I can't wait to see the finished product!! Best of luck on choosing the best prop. P.S. I've listened to alot of bad stuff on Warp & some good but I have got to say that there are alot of gyros flying with them, it is a very strong prop! ,the price is right, they are repairable, good people to deal with(Darrel),try it out & return policy,& I seem to be getting really good performance out of my 68"...... I guess I won't know the difference until I get my Prince

[Scooter]

Of all the decisions I've having to make in building my aircraft, I think the prop is proving the most difficult.

I don't know a whole lot about props, so I've been looking at all the sites and reading posts trying to learn as much as I can. With the prices I can only afford to buy one set, I need to get it right the first time.

I was at the aero-sport site a minute ago looking at their prop configurations. I noticed that at the botttom of the page it said "not approved for direct drives". I guess I could ask aero-sport, but I thought I might get one of you guys to enlighten me. In my simple way of thinking it shouldn't matter what drives the prop as long as you stay within the RPM restrictions, it fits on the hub and of course the pitch, lenght, blades, hp rating, etc. I thought it might be how fast it spins up, but don't really see that being the reason. Maybe that it is for re-drives only, it could be a balancing reason. Someone please X-Plane it to me. Thanks, Larry

[mceagle]

Larry,
Direct drive props generally spin up to 4000rpm while reduction driven props typically spin around 2000 - 2500rpm. Centripetal and gyroscopic loads are much higher at 4000rpm.

[GyroRon]

Look I won't try to twist your arm but if you got money to throw away go buy the best wiz bang quiet hight thrust prop you can find. All I know is the warp drive will take a serious beating and still be serviceable. Nearly all other makes of props will be trashed if you lose a item through the prop. I had the solid aluminum pulley and steel arm and bracket go through my prop at this past Bensen Days on my just sold Dominator. It nearly stopped the engine and made a scary sound and shook the gyro, but then a instant later it was as if nothing happened. I got it on the ground and inspected the damage - a chip out of one blade and a ding in the other at the root - and was surprised at how little damage was done. This was a part the size of my fist.

Afterwards I was talking to several people about it and they all agreed that had it been any other prop - ANY OTHER - THe prop would have come apart and could have caused a whole slew of possible Bad things - like the engine departing the gyro or the prop blades going into the rotor or slashing the keel or rudder cables etc...

I also was there when Steve McGowan lost a seat belt through his warp drive on his Trainer. Just put a chip in one blade and like I said, a little super glue with some baking soda mixed in fills the chips in nicely.

the old Warp drive Ivo props were much heavier than they are now

I just think for a pusher it is realistic to assume stuff will end up going through the prop. From a safety stand point and a money stand point the Warp Drive can't be beat.

[gyromike]

A friend of mine had a 912S and tapered-tip 3 bladed Warp Drive on his Rans S-7, and it was very quiet.

The blades were tapered, not the wide chord, and had a radiused tip on the trailing edge.

At least I think it was the trailing edge. It had a radius though.

[Scooter]

Larry,
Direct drive props generally spin up to 4000rpm while reduction driven props typically spin around 2000 - 2500rpm. Centripetal and gyroscopic loads are much higher at 4000rpm.


You are telling me something I didn't know. You must be talking about racing engines. I looked up lycoming, it's max rpm is 2700, Jabiru is around that. All the props I've looked up, max is around 3000. Now I'm not looking up those $12,000 plus props. They are just out of my league.
So if the max rpm you are goiing to turn at the prop is 3000 what difference does it make if you are using a re-drive or a direct drive? I guess I could run my Subaru 2.5 at 4,000+, but I plan on using a cable stop to prevent anything over 3000. I know I get max engine power to the prop with a re-drive, but I don't need it.
So I guess the bottom line is that if I'm not going to exceed the prop max recommendations, it doesn't matter how I spin it.

[GyroRon]

Larry I would guess they don't want their props used in a direct drive AUTO type engine conversion.

the other engines you mentioned are direct drive but turn the slower RPMS.

The auto conversions need to turn as high of a rpm as possible to make decent power - the only reason to have a re drive in the first place - So most people use a shorter prop and turn it as fast as possible to allow the engine rpm to be a close to peak power as possible. The use of a short prop is to be able to keep the tips below the speed of sound.

I guess operating their prop at these higher RPMs will cause them to come apart due to centrifical forces, hence they want you to only use them in slow turning applications.

[GyroRon]

Steve I loved the sportcopter blades. there was ZERO stick shake when I first got them. they stayed smooth for a while but I made a newbie mistake of HAMMERING the bolts in and out of the blades when I took them apart and put them together - I didn't know if you lift and or lower the blades just right the bolts will fall in or out of their holes by themselves - And so my hammering made it needed to start stringing the blades and I couldn't do that worth a crap either. So after a while, my abuse on them got them to start shaking like the rest of them, maybe worse than acceptable at times. They did perform well and If Jim could make them a whole faster I would make them my first choice for blades. But When I need something I need it today and Ernie has Dragon wings built and in Stock ready to ship. ;)

[rehler]

Chris,

You asked: "... do you mean that Ivo and Warp Drive were one at some time?"

Ivo (can't remember his last name) designed and sold what is now the "Warp Drive" prop. It was sold as the "Ivo Prop". He then sold his prop design and business. The new owners changed the name to "Warp Drive" and have been very successful for many years now.

Later, after a year or more, Ivo went back into the prop business with his new design the present "Ivo Prop" which has also been successful for many years now. The two designs are different - one flexible (Ivo) and the other solid and strong and stiff (Warp Drive). Both were designed by Ivo after he came to the US.

[rehler]

Ron, you got be thinking again. Damn!

You are right about the value of the almost undestructable Warp Drive Prop being very important for our pusher gyros!

I posted my question about which prop to use on the old conference as well as this one, as it seems to have two different groups of readers. I hate this! I wish we only had one conference for us all to use. Anyway I have received very good information on the other conference which has caused me to drop the DUC prop from consideration. So I had made up my mine to go with the Arplast prop. But then you came along with intelligent advise making me now consider the Warp Drive.

[rehler]

Scooter,

Direct drive engines without a reduction unit transfer very high pounding loads to the prop as each cylinder fires. It is much harder on the props. The following web site discusses failure of Warp Drive props on the Jabaru engine. Note the photos of the cracks in the aluminum hub. This dose not occur when reduction drives are used. It illustrates the extent of the abuse the direct drive engines transfer to the prop.

http://www.ultralightnews.ca/advisories1/warpdrivepropfailure2.htm

[GyroRon]

Go to the I need blades thread to see how I plan to cope!

[Scooter]

The advisory didn't say what caused the warp drive hub cracks. You could be right about the causes, but I'm not so sure. Could of been just a batch of faulty hubs, especially since it seemed to be only one manufacturer. Direct drives have been turning props for lots of years. Most aircraft use direct drives, don't they? I think some of them use slip clutches of sorts. I can see where a belt driven re-drive would reduce any so called piston pounding, but a gear driven one wouldn't.

Anyway Ken, thanks, good food for thought.

[blackbird]

Ok, here is some info on Warp Drive. Yes, they have been around for year. Ivo was bought out by the previous owner of the Tierra line of aircraft. Forgot his name, but he was in ultralight aircraft in the beginning.

[KenSandyEggo]

Hey, other Ken. If you want to spend some money, NSI has an in-flight adjustable prop that uses Warp blades. In fact, if you have a Warp, you can send the blades in and they'll balance them for their setup for 50 bucks and you save the cost of new blades that they would normally supply. I would love to see how low a cruise rpm that setup could get on my ship. With the price of gas going up like an Otis, it might be worth the investment of about 2G. The inflight IVO is a little less $$. I wonder which is the better product overall.

[rehler]

Ken 1,

Just today I installed my new 68" white Arplast prop (like the Magni gyros use). It is beautiful! I hope it is as good as my Sport Prop that I used on my old Verner engine. I had to buy a new prop, since my new Rotax 912S turns the prop the opposite direction.

Barry, who is now flying around the world, has the Rotax 4-stroke with the same Arplast prop. The combination seems to be well proven. I think I will be happy with mine - just hope it is quiet (turns pretty slow with the 2.43:1 reduction).

KenToo

[CLS447]

Ken, that will match the SC blades nicely! Does this mean that you are getting close?

Are you going to color the tips?

If you don't mind.... How much was it? Where did you buy it? What diameter? How do you adjust it?

Thanks Ken, Best of luck to you!

[rehler]

Chris,

Yes, I am getting very close. Still need to add the electrical and instruments.

I will leave the prop tips white. White is best seen when the prop is turning, which is one reason I got a white prop. The darker colors (black and even red) don't show up very well and I believe are not as safe.

I bought the prop direct from Arplast in France. The diameter is 1700 mm (about 67"). There is an adjustment tool that comes with the prop to set the pitch. I don't know yet what pitch to set it at. The cost was a lot, but the paperwork is at the office. I think it was 805 Euros with shipping, which would amount to $980.

[KenSandyEggo]

That's pretty close to the cost of a new Prince.

[rehler]

This is a follow up on my original post at the top (12-2-03).

Back then I had narrowed down the prop selection for my new 912S engine to:

1. Arplast - ECO PROP - as used on the Magni Gyros

2. DUC Prop http://www.duc-helices.com/technique/windspoon.htm and

http://www.microlightsport.co.uk/Ca...UCPROPELLER.htm

I chose the Arplast prop, and today I did a static run up on the ground to check my prop pitch. I did not have my helmet on so the engine and prop sound was not muffled. The engine is extremely quiet but the Arplast prop is very loud! I ran it up to 4000 rpm and stopped to put on my helmet, as the prop noise was just too much. With my helmet on it was no problem.

I made my choice and will live with it, but I wish I had gone with the DUC prop with the curved "P-Tips" similar to my old Sport Prop.

Is there anyone out there who has a DUC prop? Is it a good reliable prop? Has there been any problems with it?

I will keep my Arplast, but others might be able to take advantage of your experience.

[KenSandyEggo]

A little side-note to those RAFers and others that have added them and Sparrowhawk conversion and kit-buyers who have Trapp mufflers, clean them out once in awhile. I had the guts of mine out today (2 screws on each muffler), knocked off all the carbon dust and when I put them back in, my static thrust increased a good 100 rpm. This was while it was tied down and at full power. Remember, if you convert to Trapps and they're fairly close to the engine, remove the packing from the inside. It will crisp up (regardless of what it's called) and block the disks and could give you a surprise when you go to add throttle. I get the best performance with the maximum number of disks installed. Less and you lose top-end rpm.