Ron E a question RE: my warp drive

[greywuuf]

Well ok a couple questions.
I purchased my Warp several years ago and never got it mounted up and am sure I have lost all of the literature that was with it. I know for sure it is a 60" NON hp 2 blade.

Here's the questions,

One: what is the Max speed I can turn this thing, and what is a good Max to shoot for.. IE: if the max is 2500 what happens if I pitch it wrong and run it up once and hit 3K? not sustained but blow throw the redline on the first try.

I need a desired and a NEVER exceed.

Second, What is the best way to store one ? assembled, disassembled hanging? sitting on the hub face ?

or: have I hurt it letting it sit loosely assembled on the hub face over the winter (flat bench nothing touching the blades)?

oh and last, provided the rotation is correct does it matter if you run them tractor or pusher ?

Thanks Dan
(Dusting of my parts in anticipation of spring)

[mark treidel]

Dan, You need to privide a bit more info to give you the answers you desire. Warp Drive props are very sturdy, leaving them in the manner you describe will not affect them. 2400 rpm is tolerable but here's what I would do...you need to know the maximum rpm of you engine (red line)...then your reduction ratio...a good starting point would be about 10.5 deg...suggest you contact Warp Drive with the figures & they will tell you exactly. Once you have that information, set the prop for static rpm about 300 rpm below red line. This will give you maximum power usage of the motor. IE: My Rotax 582 with a C box with 3.0/1.0 ratio redlines at 6500 rpm. I set my pitch at 10.5 deg. static which gave me 6200 rpm in the ground test. In the air I get 6450 maximum just a hair under the redline (safe buffer for me). At maximum rpm, the prop is spinning at 2165 rpm, (6500 rpm/3) well within safe limits. WD blades are molded specifically for tractor or pusher configurations.

[greywuuf]

Well, I have B***ard combination that is not quite close to ready. I am looking for a Re-Drive and thats part of the problem. I am going to need a 3:1 or Higher (numericly) as my engine is "rated" at 8500 but will certainly not be hurt untill beyond 9 grand (I know first hand I have raced them for years)

I don't intend on turning it beyond say 7500, but without knowing the limits and the desired area of the prop, it leaves it kinda hard to choose. Also since I don't have any Dyno figure's at the slightly reduced rpm point for the engine, I will be guessing on the first go with the pitch, if i "miss" and throttle up and blow through the ceiling so to speak, at what point have I damaged the prop? I kind of need a NEVER exceed speed, and a guidline of what The prop would Like to turn. I can adjust from there.... also how about a pitch figure not to exceed ? like if I can't handle the motor at 12 Degree's go to a smaller motor ? Or something like that ... I have LOTs of options motor wise. I am just trying to match up what I have.

oh and what gives with the tractor pusher deal ? seems to me if you are turning the prop the right direction it does not matter if you are standing in front of it or behind it...... doe they do something special with the root to handle the turbulent flow on a puher or something ?

Does the Rotax box use a two gear system or three ? IE: is prop rotation the same or opposite of the motor ?

Thanks
Dan

thanks
Dan

[scottessex]

You are more concerned with the engine redline that the prop redline. Then figure out your reduction ratio and keep the prop tips well below supersonic, other wise you are just making noise and no thrust. Guys on airboats spin the bejesus out of their warp drives like 5g plus so worry about the engine speed then do the math to get the right speed for the prop dia.

What engine? if it is a rotax you should start with about 10 deg pitch, you don't want to overspeed a 2 stroke they break piston skirts when they runaway.

[greywuuf]

as far as the engine choice.... as i was saying , probably while you posted your answer to me, I have several ( all fuji, I was a factory Polaris racer for too long to run rotax) ranging from a 488 fan to a 1050 liquid triple (220+Hp)

some of them are ported more user freindly than others. I can figure the ratio I need if I know the proper speed to turn the prop. As I stated I have the Lo-Perf warp drive hub, and I can't remeber what they said the max on it was, but it was under 3 K continuous.

BTW I have a 60" two blade, what is going to be the max HP I can efectively absorb with this thing ?

Thanks
Dan

PS please lets not get into the usefullness/apropriateness of my motors. you will absolutely NOT talk me out of using the motors I have. I have had lengthy discussion with several differant industry engineers about bearing loads etc ad naseum.


suffice it to say I have motors, I have this ONE prop and I am trying to match it to one of the motors I have. it may end up as a static display it may end up as a test mule for building /testing various re-drives, it may end up on an air boat or God willing it may even end up on this gyro I have on the drawing boards.


Sorry if I sound defensive, I am just tired of all the well wisher saying well mening but totally useless things like ..."just go with a rotax and a gear box" or it will never work, "it wont handle the loads"..... I just need to know how fast to turn the prop I have,


Thanks
Dan

[dragonflyerthom]

Dan

The under 3K is right on for a WD. Anything more will be ineffective.

[scottessex]

Most gyro's in the 50-75 hp range use a 3 blade prop. 2 might not be able to soak up the power. You might even need a 4 blade for a larger engine.
If you use a belt drive on the Fugi, (j-bird sells belt redrives for fugi)
I would go with a 2.5 to 3.0 ratio, If you pitch the prop too much to try to absorb the extra power the blade tips will be stalled and you will loose thrust.

I think you can absorb around 65 hp with a 2 blade, the monarch gyro's use a 2 blade so do alot of the fixed wing ultralights.

What power is a 488? if it is rated at say 80 hp at 9500 rpm, tune it down to about 6300-7000 range, you might be getting 60-65 hp or so.
7000 max engine rpm 3.0 reduction=2333 prop rpm

then take your prop diameter, rpm etc. 60" prop at 2333 rpm =416 mph tip speed or .539 mach.

7000rpm 2.5 ratio=2800 rpm or 499 mph or .647 mach.

I have an arctic cat (suzuki) 530 l/c with a rotax A box on it, the old ratio was 2.0 to 1 and it spun the prop way too fast, it only had about 3 degrees of pitch but it would hold the engine at 6800 rpm on the ground. I just installed 2.58 gears and am going to get it set up on the test stand and run it and get some thrust numbers.

[Friendly]

Culver props had a prop program on their website that would allow you to plug in the prop , pitch and rpm. It would tell you if the prop numbers were ideal or not.
Also
CPS catalog has a great section on props and prop information that you can apply to your design.
Also I think the vortex site may have a program for the warp drive props.
Hope this helps.
I know how you feel about Rotax, I just made a bank loan to buy an new 582.
I have missed a lot of flying trying to make various combinations work. I want to fly so I swallowed my pride and followed suit.
But I should have something reliable to fly while I , like you ,look for the Rotax alternative. Keep us posted. More people than you know would like to see a good alternative to Rotax.

[greywuuf]

Scott, thanks

Yeah I know of about 3 options for re-drives, one I will build myself and will have control of the ratio. I can do long division so figuring the ratio is no problem (granted looking at my spelling one might question my math skills)

My Big unknown, is what pitch and what RPM? also what figure are you using for mach ? as the speed of sound chnges with air density. I was figuring on aprox 1000 fps as that seems to be where my subsonic rifle loads start going sonic ( I am a gunsmith and amatuer ballastician as well.... pretty well versed in the math/physic of speed/sound)

I know there is a limit placed on the warp hub as to rotational stress, I guess I will just call warp and ask. Though the original intent of this post was to ask the person that said " ask me about warp drive aplications" this question.


I don't have accurate info on my various motors as far as HP (Tq) figures at various RPM ( dyno's are hard to come by in this neck of the woods and Polaris (fUji engines ) was not real free with the information in their literature ( and it would be suspect anyway) This is why the questions on Pitch , and effects or overspeed.

at what point does the pitch become excessive? is it noticeable ( drop off in thrust ? change in sound? )

the 488 was only rated in the high 50's ( a guess as I have never seen it in print, but it compares favorably to others in this size and port config) at 8500 RPM. this motor is likely to give up less in the lower rev region due to port and pipe configuration. I have several motors rated high, but they are more "radical" and will suffer greater loss's at low R's.


I will most likely try the 488 a 500 liquid ( actually 488 just marketed as a 500) as I have the liquid and my fan motor went to the coast to be a trapping sled this winter, and I am not sure it is worth the hassle to get it shipped back.

I will start with a 3:1 reduction and shoot for about 7500 engine and as per your suggestion start with a 10.5 pitch. My only concern is... if for some reason the engine "comes on the pipe and tach's 9200 am I going to grenade my prop ? Guaranteed i will be pulling the tether in short order, but I would like to avoid that scenario entirely if possible.

Thanks for all the input so far!

Dan

[Brent_Brown]

I would try to keep ity under 7000 might last longer

[scottessex]

I used 75 degrees F as the basis for the calc, but if you are so close to mach that a few degrees in temp make it go supersonic, than you are already out of the ballpark with the prop speed.


Just remember you are going to have the engine "loaded" the whole time you are flying, so de tune down to a lower rpm in the 6-7000 rpm range and the engine will still be working plenty hard, just not right on the edge of its limits.
You will not explode your prop it you momentarily over speed.

Lets say you have your re-drive set up ready to run and all everything is good.
Pitch your prop to 10 degrees, run the engine up slowly, 500 rpm at a time, if you are getting close to 7000 rpm and still have throttle left, you will need more pitch you want the pitch in the prop to limit the rpm, the propeller is the only thing holding the engine back, now after you get your RPM close you will need to re-jet your carbs so you are around 1050-1150 EGT, pitching the prop goes hand in hand with jetting, just taking a little pitch out of the prop can cause the egt to rise, too much pitch can cause the engine to load up,
EGT's run cooler but CHT will go way up,

So bottom line is, get the engine set up with a gear ratio that is known to work with a 2 blade prop, then start with a pitch to load the engine, and then set aside a whole weekend to dial the engine in by pitching the prop and jetting.

Rotax gives you a jetting chart for thier engines and adjustment for alt.
So at least you have a baseline to start from.

On the suzuki I had nothing to go by, other than buying a handfull of jets and re jetting and messing with the prop untill all the gauges were in the green, rpm-egt-cht.

[greywuuf]

Sounds like a plan. good thing I have a pot full of jets

Got any specifics on that Suzuki? what prop and what did you end up getting for thrust ?

is that a 550 ?

PS, I bet that is the fastest engine stand in the neighborhood;-)


DUHH!!!!! Don't know how I missed it in your previous post, Scott please disregard these stupid and redundant questions