daggets

what kind of engine and batteries could spin an 11/7 prop at 15000 rpm?
is there a setting that could do that at "the king of hobby"?

anybody has some experience?

best regards, daggets

Mike Wiz

My Feedback: (2)

Take a look here. http://www.rcuniverse.com/forum/fb.asp?m=10033802

That will get you pretty close.

Dean Pappas

Hello, Daggets!
I do not think that you want to turn an 11-7 at 15,000 RPM, unless you are looking to waste energy and make a lot of noise.
Seriously, the propellor tip howl and the energy wasted at such tip velocities is contradictory to good performance.

I think you will be best withthe following:
A 5S 4000 mAH ~ 5000 mAH battery (1/2 of a modern F3A pack)
An outrunner of Kv = 650 (like an Electrifly Rimfire 60 or Eflite Power 46)
A prop ranging from an 11-10 to a 12-12. Currents will range from 55A with the smaller prop to near 70 with the largest. Expect about 10,000 RPM.
The motors specified will weigh ~ 300 grams. The overall weight of the system will be between 950 and 1000 grams: compare this to a 60 / pipe / tank / fuel!

Regards,
Dean Pappas

KLXMASTER14

Electric Classic Pattern?

Isn't that sort of like anhydrous water?





























Just kidding! I hope that one of you guys work out that combo. It will open the door for more guys to give Classic Pattern a "whirl".

-Robert

daggets

thank you very much for the answer...
I m flying an heavy curare equipped with an ys 60 fr, running at about 15000 rpm and an 11/7.
That change the plane, as it is really ballistic, and flies straight, due to the speed...
the same plane has flown with an os 61 sf pump, and, the speed is a lot less, the "big" 12/10 prop induce a lot of gyroscopic and torque effect, does not fly the same as it was in the beginning of the eighties...

an electric classic pattern sounds a bit a shame...

On the other side, electric propulsion has made so much progress, it could be a pity to do no use it...

Main thing for a classic, go ballistic!

8178

My Feedback: (17)

For me the sound of a screaming 61 on pipe and the sweet smell of burning alcohol, nitro and castor oil is part of the hobby that I could never live without. Also like the quiet time spent cleaning the oil off the airframe after a great day of flying. Life doesn’t get much better than that!

dhal22

Mike, that is well said. we should use that statement as our anthem. thanks for the well said statement.

Mike Wiz

My Feedback: (2)

Dean, you're right. Ideally you want to swing a large prop at a slower speed because it's more efficent than a small prop spinning fast. Why? Because, in simple terms, the fast prop beats the air and the slow one slices through it. Generally an electric power system that has been optimised for a plane this size would swing a 15" or even a 16" prop. The problem here is the classic pattern airframes, particularly ones with tricycle retracts don't lend themselves so well to large diameter props. So, if you can make a 12x12 work that's going to help. Another thing is to try a geared inrunner in a clamshell mount bolted right to the original glow mount. It should fit with ease. Also, if you can, look to using 6S instead of 5S. Higher voltage and lower current runs cooler. A little later, I'll see if I can come up with an inrunner and an outrunner power system designed around a 12x12 prop and a 6S battery and post it here.

Mike Wiz

My Feedback: (2)

.<Deleted Double Post>

Mike Wiz

My Feedback: (2)

<Double post again.... sheesh>

stuntflyr

Do you guys think the 12x12 can mitigate the GP and P-Factor destabilization to a high percentage with stock Classic designs control surfaces areas, etc compared to a bigger prop? Big diameter and/or big pitch sure does make a difference and the Classics were built for small props and small pitch values. That is the thing that I see being a negative for electric.
We all seem to know, or at least have heard that electric motors will turn big, efficient props. But; with these airframes that are known to fly very well with little props, why doesn't the conversation go towards making the electric motor turn the small prop at like 61 rpm's?
I thought the electric motor will do whatever we want it to do. It's supposed to be magic.

Chris...

Dean Pappas

In the late '80s we were pretty much all flying with 11-11's, 12-10's, 12-11's, 21-12's. A healthy YS long in a clean airplane with an APC 12-12 was fast! It was quiet too.
A few of us were even flying 12-13's on very light (7-1/2 pound) planes, but engine/pie setup got kinda fussy.

Why not small props at high RPM? They don't pull as well, they make awful noise, and they don't brake downhill as well. Other than that ... not much.
take care,
Dean Pappas

RCDENT

My Feedback: (2)

Thanks for all the good info Dean! What we are really looking for is the "Rossi .60" of electric motors. I'm no engineer, but I'm aware that elecs have different torque characteristics than 2-stroke glow motors. Thus the comments about higher pitch props seem to make sense. Like many of us, I'm sort of addicted to the scream of piped .60's, but I just got back from a warbird weekend with my newly-electric-powered P-51. I'll have to admit, there is a lure to the clean, quiet power.
Prior to the conversion, I flew the plane with an OS .61 FS with Slim Line muffler. Being around 9 lbs, with 760 sq in of wing, it flew much like a pattern ship with out the pipe. With the elec setup, it really flies about the same. Trouble is, it depends on a 15-16 in dia prop - not very compatible with a ballistic, trike gear pattern ship. I'm half tempted to try the P7 with the setup mentioned above! I'm all for retro, but.......you can't stand in the same river twice. Maybe it's time for more blending of old and new!

Dewey Newbold

cygnet

My Feedback: (33)

Try this scorpion 4020-10 or 4020-8 on 6S I use this and turn a 12x6 at 13000 in a 10 min flight I use 3800 mah.

lfinney

My Feedback: (44)

none of the physical dynamics change on old school pattern planes, just because you use electric motors. the issue is using a electric motor that has similar characteristics as the glow engines , so a inrunner or high kv/ rpm electric package would be a better choice and yes there are still high pitch 11 and 12 inch apc pattern props so his is where one need s to look for a correct motor package for ballistic pattern lanes

daggets

here we are...

Mike Wiz

My Feedback: (2)

That looks like a pretty good outrunner setup, cygnet.

Mike Wiz

My Feedback: (2)

Here is one with an geared inrunner and a 12x8 prop and a 6S battery that looks quite good too.

MotOpinion - P7
800ft above Sea Level, 29.92inHg, 56°F

Motor: Hacker B50 10S; 3640rpm/V; 2.7A no-load; 0.009 Ohms.
Battery: Thunder Power TP5000 (G4 ProPower 30C) (30C); 6 cells; 5000mAh @ 3.7V; 0.003 Ohms/cell.
Speed Control: Castle Creations Phoenix 80; 0.001 Ohms; High rate.
Drive System: APC 12x8; 12x8 (Pconst=1.11; Tconst=0.95) geared 6.7:1 (Eff=95%).
Airframe: Phoenix 7; 690sq.in; 118.7oz RTF; 24.8oz/sq.ft; Cd=0.047; Cl=0.47; Clopt=0.67; Clmax=1.24.
Stats: 151 W/lb in; 133 W/lb out; 23mph stall; 31mph opt @ 47% (63:10, 83°F); 38mph level @ 54% (49:31, 87°F); 2124ft/min @ 50.2°; -252ft/min @ -5.2°.

Possible Power System Problems:

The full-throttle motor current at the best lift-to-drag ratio airspeed (53.5A) is lower than the motor's maximum efficiency current (79.7A). A higher current level would improve system efficiency. Current can be increased by using more cells, a larger diameter or higher pitched propeller, a lower gear ratio, or some combination of these methods. (In my opinion, there is no good reason to increase the current draw here.)

Power System Notes:

The voltage (21.2V) exceeds 12V. Be sure the speed control is rated for at least the number of cells specified above.

Possible Aerodynamic Problems:

The static pitch speed (85mph) is greater than 3 times the stall speed (23mph), which might make take-off or hand launching difficult, and is inefficient in flight unless high speeds are intended. Pitch speed can be decreased by using a lower pitched and/or larger diameter propeller, a higher gear ratio, a lower cell count, or some combination of these methods. (I think making the plane fast is the whole point. I many times ingore this message from the program and it's never been a problem.)

Aerodynamic Notes:

With a wing loading of 24.8oz/sq.ft, a model of this size will have flying characteristics suited to the intermediate pilot, for use in calm to moderate wind conditions.
The static thrust (118.8oz) to weight (118.7oz) ratio is 1:1, which will result in very short take-off runs, no difficulty taking off from grass surfaces (assuming sufficiently large wheels), and steep climb-outs. At the best lift-to-drag ratio airspeed, the excess-thrust (89oz) to weight (118.7oz) ratio is 0.75:1, which will give very steep climbs and incredible acceleration. This model can easily do consecutive loops, and has sufficient in-flight thrust for any aerobatic maneuver.

General Notes:

This analysis is based on calculations that take motor heating effects into account.
These calculations are based on mathematical models that may not account for all limitations of the components used. Always consult the power system component manufacturers to ensure that no limits (current, rpm, etc.) are being exceeded.

Mike Wiz

My Feedback: (2)

See the attached link and you'll see what a clamshell mount is. With one of these on an airframe like these classic pattern planes, you can bolt an inrunner motor right to the old fashioned glow motor mount. It's simple and effective.

Here is the link. http://www.nesail.com/detail.php?productID=3013

daggets

http://www.hacker-motor-shop.com/e-v...3&c=2161&p=216

276 euros..... no controller, no batteries....

Mike Wiz

My Feedback: (2)

Yep. A good quality geared inrunner isn't cheap. You can get a Hacker, or Neu that are all similar and tops in quality and they'll run you about $350 here in the states. A Kontronik system that is similar can be bought in Canada from Icare for about $270. You can also buy a similar spec Hobby King motor for next to nothing but I'm not sure where you'd get a gear box for it and I know the quality isn't the same.

There is no doubt that a good inrunner with a good gear box is an expensive motor. But you get a 95% or higher efficiency motor that will last and last and last..... It would be nice if Scorpion would have made good on their promise to offer an affordable alternative to the inrunner motors out there but so far, they are vaporware.

With that in mind, try the outrunner setup mentioned above or something similar. They definitely are cheaper and less maintenance than a geared inrunner.

Mike Wiz

My Feedback: (2)

OK, so a little research turned up an affordable geared inrunner solution. This particular motor and gear box can be bought for a little over $100.
Here is the link to the motor. http://www.himodel.com/electric/5mm_..._5408409S.html
And here is the gearbox. http://www.himodel.com/electric/Feig...7_1_Ratio.html
Will it last and last and last, like a Hacker or a Nue or a Kontronik? Probably not..... But you can give one a try for an affordable price and see what you think for yourself.

Here is the Motocalc comps I ran with this particular motor.

MotOpinion - P7 with Feigao 9S
800ft above Sea Level, 29.92inHg, 56°F

Motor: Feigao 540S 9T (5408409S); 3943rpm/V; 3.6A no-load; 0.0077 Ohms.
Battery: Thunder Power TP5000 (G4 ProPower 30C) (30C); 6 cells; 5000mAh @ 3.7V; 0.003 Ohms/cell.
Speed Control: Castle Creations Phoenix 80; 0.001 Ohms; High rate.
Drive System: APC 12x8; 12x8 (Pconst=1.08; Tconst=1) geared 6.7:1 (Eff=95%).
Airframe: Phoenix 7; 690sq.in; 119.6oz RTF; 25oz/sq.ft; Cd=0.047; Cl=0.47; Clopt=0.67; Clmax=1.24.
Stats: 180 W/lb in; 157 W/lb out; 23mph stall; 32mph opt @ 44% (58:27, 87°F); 38mph level @ 50% (48:22, 91°F); 2816ft/min @ 90°; -253ft/min @ -5.2°.

Possible Power System Problems:

The full-throttle motor current at the best lift-to-drag ratio airspeed (65A) is lower than the motor's maximum efficiency current (99A). A higher current level would improve system efficiency. Current can be increased by using more cells, a larger diameter or higher pitched propeller, a lower gear ratio, or some combination of these methods.

Power System Notes:

The voltage (21V) exceeds 12V. Be sure the speed control is rated for at least the number of cells specified above.

Possible Aerodynamic Problems:

The static pitch speed (91mph) is much greater than 3 times the stall speed (23mph), which might make take-off or hand launching very difficult, and is inefficient in flight unless very high speeds are intended. Pitch speed can be decreased by using a lower pitched and/or larger diameter propeller, a higher gear ratio, a lower cell count, or some combination of these methods.

Aerodynamic Notes:

Due to some of the potential problems listed above, this model may require an experienced pilot.
The static thrust (144.6oz) to weight (119.6oz) ratio is 1.21:1, which will result in extremely short take-off runs, no difficulty taking off from grass surfaces (assuming sufficiently large wheels), and vertical climb-outs. This model will probably be able to perform a hover or torque roll.
At the best lift-to-drag ratio airspeed, the excess-thrust (112.3oz) to weight (119.6oz) ratio is 0.94:1, which will give very steep climbs and incredible acceleration. This model can easily do consecutive loops, and has sufficient in-flight thrust for any aerobatic maneuver.

Trisquire

Turning an 11-7 at 15,000 RPM is certainly no less efficient than turning the ducted fan rotor blades on a jet. I don't know if you've seen any electric ducted fans lately, but they are not lacking in performance.

Tom

Mike Wiz

My Feedback: (2)

I'm not so certain about that. I'm no expert on ducted fans but I think there is somthing else happening there. Could you take the fan blades and attach them to the front of a plane and spin it as fast as it would in a duct and have the same thrust? I don't think so but then again, I'm not an expert in that area.

daggets

and most of all, this is the recepe for having a classic pattern!