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Electric Stunt => Gettin all AMP'ed up! => Topic started by: Dennis Adamisin on September 09, 2009, 10:53:17 AM
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I'll try to be brief - but need your feedback quickly.
We recently joined the ranks of those converted to useing LH or Pusher props. The performance difference was in our case nothing short of stupendous. THe only problem is the current SELECTION of pushers is slim. Most are 2:1 dia:pitch ratios, which are good for efficient THRUST but do not BRAKE as well as they could. We need lower pitch.
We have been in contact with APC and they are willing to introduce a new size for a 200 unit order. We are willing to commit to buy those 200, but will not use them all ourselves! YOU, dear SH friends are the likely customer base!
The size we are thinking about is a 13x4.5 Pusher:
* The diameter is somewhat larger than most folks use, but it is easy to trim down. Also there are a lot of people looking at bigger power systems.
* We have noted that a lot of the SH folks have been de-pitching their 6-pitch props to 4.5 to 5 range.
* We have recent experience with a Strega flying with a 13x4 (RH) that really works well at 11,000 RPM, but a little slower would be nice. We think the extra 1/2" pitch will let it fly around 10,300 or so...
* The expected price for the new prop is $7.50, lead time roughly 30 days from the commitment to buy.
* The props would be essentially the same as waht we have come to expect of APC-E props, just a different size.
SO THE QUESTIONS ARE:
* Are YOU interested in purchasing this size prop - and roughly (non binding) how many?
* If you have any concerns about this size, what ALTERNATIVE size would make it an easier for you to commit to buy?
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Denny,
I am interested, most definetly!
I am inclined to lean towards the 4.5 pitch as well.
would be interesting to know if they intend to make the airfoil like the 12x6 E or the others . It seems the 12x6 E has a slightly more significant undercamber.
I would love to see a 12 x 4.5, but like you say , the 13 can be cut down if needed
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Put me down for 4 to 6 for right now.
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I'd take 4 to start with. Maybe a few more if required. This could be a good prop for the electric Impact I want to build.
John
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You can put me in for 4 props y1 y1 y1
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Hi Dennis,
Yes, put me down for 5. tell Fred I said hello too. The 13-4.5 figure sounds good:
1) they will clip nicely, leaving wide blades that folks will end up liking very much
2) it's easier to twist in additional pitch versus taking it out
3) the 13" dia and 10,000 RPM still keeps fan noise under control.
Thaks for making this happen,
Dean P.
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Hi Denny:
Count on me for at least 5 of them...
Bob Hunt
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I'll take 4 props.
At least with pushers, most IC guys won't be able to use them! n1. Unless they make bonafide pusher planes!
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Sign me up for 4 props. Will be good for the E-Legacy that is looming in my future. Or at least an E-Score. Have both, not decided which to electrify.
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I'm in for 6 or half a dozen .
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Dennis
Put me down for 4.
bob branch
(another strega coming in a few weeks)
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Put me down for 4. Thanks, Dennis.
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I'll take 4 of whatever you guys decide to come up with. It will be nice to have another option. Thanks!!
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Hi Denis
I will take four also 13x4.5
all the best petejavascript:void(0);
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4 for me too!!!!!! Make that 8 Jose wants to try a few.
William
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We went ahead and committed to APC for 200 props - the minimum order. They are cutting a tool and target delivery could be 9/25. thus we should all be able to get some flight tests before the snow flies.
If everyone (plus if a few more!) come through with the quantities they indicated we can almost not go broke on this! #^ When the delivery is more solid I will send you all PM's and ask for your shipping addy's - and MONEY! Expect the best way to ship will be USPS Prioity, shipping should be around $5 per order - except for that Kiwi fellow...!
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You Adamisins are just so "pushy"! >:D
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Let me know ,, I have my checkbook ready,,
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Pusher props forever!
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Sounds Good!!!!
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You Adamisins are just so "pushy"! >:D
OK you're gonna love this:
Alan: is that a "Left Handed" compliment??? (RIMSHOT!) LL~ VD~ 010! (PE**)
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Using the rh rule, I guess so!
Like I said, my motivation is to use a prop that the glow guys can't!! If we can convince them that ccw (from the front) solves all of stunts trim problems, it will drive them crazy! y1
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I wonder who amongst the 3D prop hanger crowd will get one so he can do torque rolls the OPPOSITE of everyone elses? n~
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Hi Dennis.
How are U, Put me down for 4 also I've been foolin around with the regular 13x4 prop on a 61 powered
Stiletto (aka sluggo) for about 20-30 flights seems to work real well. 2 do so U must use precautions.
inspect props for any defects especially around the hub. Any stress induced on that area WILL cause them 2
fail. Have seen that once. With that being said I have a carbon fiber version of the prop I'm cutting down 2
12in and repitching 2 4.5-5ins. Now I happen 2 know that a 3 blade version of same prop is being made.
in CF.Would any one b interested in a 3 blade from APC?
Later,
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I'm slowly getting rid of my massive stunt ENGINE stash while at the same time accumulating and static testing several MOTORS.
Your Mythbuster was inspirational. I have a new design and construction method for take apart. Hopefully two different looking planes with and old and new name by next spring.
5 Pushers for me please.
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A bunch of us NorCal types will be at Woodland, where APC props are made, over the September 26-27 weekend for the infamous Meet n' Meat contest, a madcap Uncle Jimby affair. Would it be at all helpful for any of us to visit the plant and check on progress or even pick up some props (if APC allows)?
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Hi Dennis.
How are U, Put me down for 4 also I've been foolin around with the regular 13x6 prop on a 61 powered
Stiletto (aka sluggo) for about 20-30 flights seems to work real well. 2 do so U must use precautions.
inspect props for any defects especially around the hub. Any stress induced on that area WILL cause them 2
fail. Have seen that once. With that being said I have a carbon fiber version of the prop I'm cutting down 2
12in and repitching 2 4.5-5ins. Now I happen 2 know that a 3 blade version of same prop is being made.
in CF.Would any one b interested in a 3 blade from APC?
Later,
I for one would like to see some 3 blade props, especially in the 11" to 12" range, simply because I think I can still use a heavier prop load, but my 40-sized planes are already looking like Storks with oversized wheels! Maybe I need to move to the Corsair bent wing design to get more prop clearance!
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Hi Dennis
Put me down for 6 props.
Walt Brownell
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I asked Fred about making a 3-blade and he said that he wouldn't because of efficiency losses. I used to fly with nothing but 3-blade props, so I guess I have much to learn about props. This prop was a first step though and maybe if we can show enough interest in it, Fred might think about it and some other sizes.
Lets all keep buying props and shame him into it!!!
I really can't thank Fred enough for doing this. What another improvement in ECL this prop will make.
Archie Adamisin
Muncie, Indiana
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I asked Fred about making a 3-blade and he said that he wouldn't because of efficiency losses. I used to fly with nothing but 3-blade props, so I guess I have much to learn about props. This prop was a first step though and maybe if we can show enough interest in it, Fred might think about it and some other sizes.
Lets all keep buying props and shame him into it!!!
I really can't thank Fred enough for doing this. What another improvement in ECL this prop will make.
Archie Adamisin
Muncie, Indiana
I am curious to how much you lose. In our cases, we would still dial in the same thrust (presumably at a lower rpm). In my old prop study, I was seeing efficiency losses of about 10% comparing a 2 blade with a 3 blade (same diameter).....
If it is that big a deal, how about a single blade prop!
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Xoar has a few sizes of three blade electric props with a similar blade profile to the two-blade ones. In fact they appear to have the two-blade blades with the hub nipped off at a 120 degree angle and some kind of joiner in the middle. However, so far I haven't found anyone who actually has them to sell.
John
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I wonder who amongst the 3D prop hanger crowd will get one so he can do torque rolls the OPPOSITE of everyone elses? n~
Only if he flies nose down!
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I am in for 5, thanks
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Dennis,
Will these props come to you or will they be available directly from APC. I posted earlier that I would like 5 just need to know who to contact around the 24th.
Thanks Tim
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Dennis,
Will these props come to you or will they be available directly from APC. I posted earlier that I would like 5 just need to know who to contact around the 24th.
Thanks Tim
Hi Tim
First off, I really got a kick out of your post in the Open Forum asking about 13x5 electric pushers! I thought HEY we got this guy covered! ;D
The new prop is a special order the first 200 are coming to me, this was the minimum size order to get them to tool up the new size. When the props get here I will PM an invoice (for lack of a better term) to all who have responded for the number of props @ $7.50 each plus $5 shipping and ask for their check, MO, or PayPal. I expect to ship USPS Priority. Overseas orders are easier via PayPal, and shipping will be at cost.
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I got a general question regarding pusher props, I hope you dont mind if I use this thread for that. My Turnigy motors has a built-in fan that, in the case of a rear mounted motor, sucks air into the motor. This will probablyb only work if a "normal" (not pusher) is used. If a pusher is used the motor turns in the other direction and the fan will probably not work. Will this be a problem? I'm a little tempted to try a 12x6 pusher on my Nobler.
/Andreas
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Andeas,
The fan that is machined in the case is meant I think for helis and enclosed in a shroud. In our application, I don't see this being an issue. I have run them either way and not seen an issue.
Take Care,
Archie Adamisin
Muncie, Indiana
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Yes, Andreas, this could be a problem.
You will have to look at the way the fan is built, and maybe ask the manufacturer.
If the fan looks like a small turbine, as some do, then this is a problem. If the fan is a simple centrifugal type, with exits that run straight out from the center, then it should be okay.
Do you have a closeup picture or two?
Dean Pappas
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Archie: Ok, sounds good.
Dean: Well its neither of them, the fan "blades" exits in a curved shape from the hub. They are however not cut to a turbine shape. See pic:
/Andreas
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Thanks Dennis,
I also thought is was weird how I was just requesting information on a 13-5 and how great my airplane would fly with it, and the answer appeared in this post. Thanks so much. Just let me know when they arrive, I am anxiously waiting :)
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Regarding the shape of the radial struts that support the outrunner bell, it probably doesn't matter much which way it turns. The struts are just milled in and don't really have a pitch and the curve of the struts won't have a lot of influence. The root pitch of the prop will blow air inwards and the centrifugal motion created by the outrunner bell rotation will counter that flow to some degree. The best pattern would be to pick up some ram air from the nose and duct it into the aft end of the motor, then expel it somewhere else. This will take some time and planning in the installation, probably more than most folks would do. The motor can actually get pretty hot without damage, but of course there is a limit to how hot.
If in doubt, run the motor with no prop and blow some smoke into the vicinity to see the flow pattern. That would be a good experiment to post here.
John
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I just spoke with Buddy Wieder and he wants to reserve 6 props also. Buddy flew my electrified Genesis Extreme just one time and vowed to make the switch to electric for next year. He's been working hard on his new Ryan's Eagle design that will mount an AXI 2826-10.
I'll try to attach a photo of it here...
Bob Hunt
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Folks:
Have receivd th first 10 pcs sample of the 200 piece order for the new 13x4.5 Electric Pusher prop. APC is printing labels, and should be shipping the other 190 props very soon.
Thus for all you you who have indicated you wanted some, I will be sending you a PM with payment info and requesting your shipping addy. As stated before the cost will be $7.50 per prop with $5 shipping USPS Priority to lower 48. Not all 200 have been spoken for so if you wanta couple extra please say so. Overseas folks: please send me your addy, Ill have to dig a little deeper to determine what your shipping costs will be...
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Please check your PM.
Thanks
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I flew one tonight. I cut it down to 12". I needed to run it at 10,600 rpm to get 5.25 laps on 63 foot lines. Very nice. I'll fly one this weekend at the St. Louis contest. Supposed to be a bit windy too. A good time to check for windup!
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Dennis,
Thanks for getting these props. They are affording me too much fun over on SSW! LL~
Maybe I'll even have to try a pusher!
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OK folks here's ANOTHER update
I expected them on Friday but the durned things just arrived today (Tuesday) I am preparing 20 (!!!) boxes to carry to the Post Office. they will FINALLY leave here Weds 9/30, you ought to have them by Friday or Saturday.
MANY THANKS TO ALL WHO HAVE ORDERED! (AND PAID!!!)
With your orders to date and one person's generous donation, I am ALMOST at break even. The way I understand it, APC will make this a regular production prop, but I am going to ask that you order any spares or send your friends over to order from me - just until this initial sample is exhausted.
BTW Alan, I see how much fun you are having over on SSW with this:
10 Cox reedies? ???
Running backwards? ??? LL~
On Purpose? ??? :o LL~
At the same time??? :o ??? 8) LL~ 8) LL~
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Well if I can get Dan to make a reverse crank for a PA75, it would have been worth the $35 for the props!
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Dennis,
Thanks for getting these props to the market. As you know, I have used them with success on the new lighter plane (~60 oz). It works great there.
I have now tried them on the biggest plane I have, the 75 ounce AAE. With a little fiddling, it works quite nice. I didn't have exactly the right KV motor of it, so I was running with little rpm reserve, and ended up slowing down a little at the end of the flight. The right KV motor will fix that (and it figures it's the one motor in the 25 series line I don't have!).
One other interesting note is that the APC prop used about the same energy to complete a flight as the other carbon prop I was using, but did such a slower lap times (~3000 mah). I would have to fly them back to back several times to see which I prefer on that plane. IF the APC comes in second, it would be a close second, but the price is right!!!!
Thanks again Dennis.
Paul Walker
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Hi Paul,
I was wondering if you ever got to try the prop on one of the heavier birds. THANKS for the feedback on that. Curious: what is the "baseline" carbon prop you are comparing too?
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Hi Paul,
I was wondering if you ever got to try the prop on one of the heavier birds. THANKS for the feedback on that. Curious: what is the "baseline" carbon prop you are comparing too?
It's a wide blade, but thin, 13.3" in dia, and between 6 and 7 inches of pitch.
Paul