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Old Aug 26, 2006, 04:12 PM
Just here to fly stuff
LeadSled's Avatar
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F-27C Stryker - Beyond the Parkflyer

I was at the hobby store and saw it on the shelves and had to get it.
I first started on the F-27B and loved it, and after a year I am coming back to the Stryker, but to a more "advanced" version.
First impressions. Well, the battery is still charging.
But, here is what I can say.
The radio is very cheap feeling, but it is a 72mhz channel 16 radio, and has 4 channels. Not only that it does have servo reversing and mix. Much better than the usual radio from Parkzone.
The plane feels a lot stronger than the F-27B. The B had some flex to the wing, but the C feels more rigid. I tested the engine, and it seems very strong. I like the safeties that have been placed in the plane to prevent accident and. They include not being able to start the engine when the radio turns on to a series of beeps that warns the pilot the engine is ready. Also the speed control is programmable from the radio to fit the pilot wants. The mounting of the engine looks solid and the wiring looks good.
The paint scheme on the plane is great. Much better than anything else I have seen out of a box. Overall quality and feel of the plane is good, much better than the B.
The charger is like the radio, cheap feeling, but has a lot of functionality for the price. It has cell balancing and multiple sounds and lights to let the user know what is going on.
It is clear that this plane was built for someone that is not the most tech savy, such as myself. Also, assembly time on the plane was less than 5 minutes, and the intructions in the manual and charger are great.
Here are some pics. Hopefully after the maden flight it will look the same.
Just looking at it, it looks like an impressive plane. Now I am going to take it to a local field.
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Old Aug 26, 2006, 11:35 PM
Just here to fly stuff
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I got to fly the F27C today. It was great. Launch was very easy. Just a hard level throw and light the engine. I did the whole flight on the low rate setting for the controls. Climb out was excellent. Verticle is unlimited. I made about 10 verticle climbs to the edge of my vision.
Overall control of the plane is excellent. The plane can turn in a very small area at full thottle. Also, the controls seem fast and the plane does not get away from you. It seems more stable than the F27B. I think the brushless engine gives the pilot more control. Gliding the C is also very easy. On a couple of climbs I shut down the engine at max altitude and enjoyed a few minutes of gliding. Also, you can fly this plane very slow, and landing speed was very slow.
The only thing is that this is not an 80 mph plane. I made many high speed passes over the field, and some in a dive It was not as fast as I thought it would be.
Not yet, maybe it needs a few flights to break the engine in, but it is fast.
Overall, this is a great plane, very easy to fly, and has a lot more capability than the F27B.
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Old Aug 27, 2006, 10:18 AM
Designer of Flying Things
-=SLaPPiE=-'s Avatar
Overland Park,Kansas
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Howdy Leadsled,

Thanks for the info. I would not expect a noticable performance change after break in, cause we are talking about the bearings only on a brushless motor. Only overheating will really make much difference, and that's no good. It's good to hear that you get good vert. on the stock setup.

I'm kind of interested in the motor and prop on that thing.
I would like to try to place that 1880 kv motor in the slew of others out there.
My only interest is the performance of the semi low price motor.

If you can provide any performance data, please do. Things like RPM's at what voltage, and amperage would be great, but RPM on a full charge would still be of interest. Motor weight would be nice to confirm.

It would be helpfull to compaire to known values to to test with an APC 6 x 4 prop.

For tweaking more speed out of it, it would be nice to know what kind of amperage the stock setup is pulling with the stock prop, just to see if there was room to prop it for a bit for more speed.

If you don't have a watt meter, the new e-flite is cheap and does up to 120 amps. It will also give voltage, watts, and milliamp/hours. Any tach should work.

I understand if you don't have these tools, as that's what is nice about a RTF plane. Everything is already sized right.

Happy Flying,
Rich
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Old Aug 27, 2006, 12:22 PM
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Wayne V's Avatar
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Well lets see,
1880kv*11.1V=20868RPM
20868RPM*4 (prop pitch)=83472 in/min.
83472 in/min. / 12=6956 ft/min
6956 ft/min * 60= 417360 ft/hr
417360 ft/hr / 5250= 79.5MPH

So the props pitch speed is 79.5 MPH so i would doubt the plane would go 80MPH in level flight, no plane is 100% efficient. Now a little more voltage or higher KV will get you there.
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Old Aug 27, 2006, 09:00 PM
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Wayne, that was cool what you did. I am not going to pretend to understand what you did though. Wish I had more time to study and build these things but time is very limited.
I got a second flight with the plane today. Once again I was very happy with the performance. It is a very stable and easy plane to fly. I took it to a larger field and it was great to open the plane up. The controls are very smooth. Rolls, loops, outside loops, and verticle performance is awesome.
I am depressed that I have to put the plane away till next weekend, busy week ahead.

Cheers
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Old Aug 28, 2006, 08:43 AM
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Leadsled, it's quite easy to find out the pitch speed, the only variable you really need to know is the RPM for any given prop.
RPM*PITCH/12*60/5250=Pitch speed
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Old Aug 28, 2006, 12:08 PM
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Thanks for the info Wayne.
Question, how do you know if you have the right prop for the plane - The prop is correct for the motor and power?
I just ask because your earlier reply said the pitch speed was 79.5. Which makes me wonder if that is how they calculated the advertised 80 mph. This plane is no where near that. I do not have a radar gun, but it does not look that fast. Could there be a prop that would better use the planes setup?
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Old Aug 28, 2006, 12:54 PM
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well, if when testing the plane, the battery voltage was higher than 11.1v ( most fully charged packs are higher than 11.1v ) the RPM would be higher which would mean a faster flying plane. Ever notice the first minute of flight seems better than the rest. I've bought a couple of glow motors and i'm starting to really like them, cheap power, and the SAME power throughout the flight. I still fly my electrics though, but glow is starting to win me over.
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Old Aug 28, 2006, 01:35 PM
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More like:
RPM*PITCH/12*60/5250=Pitch speed x Inefficiency of airframe




Quote:
Originally Posted by Wayne V
Leadsled, it's quite easy to find out the pitch speed, the only variable you really need to know is the RPM for any given prop.
RPM*PITCH/12*60/5250=Pitch speed
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Old Aug 28, 2006, 03:16 PM
Designer of Flying Things
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Overland Park,Kansas
Joined Apr 2004
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Yea, and if we knew what the RPM was, we might actually have some useful real world info to talk about. If we knew the RPM only we could assume the prop was holding it's pitch and guestimate speed knowing that a brick and a dart would actually fly at much different speeds due to drag differences.
I don't wanna use the manufacturers kv rating for anything, but an unloaded RPM, as a guide for selection. The RPM is going to drop as the pitch number increases above the no load kv number. You can crunch lots of cool numbers out of a kv rating, but unless you fly in a vacuum.....wait..props won't move air unless there is air to move..

As you can imagine, altitude and temperature play key roles in estimating actual flying speed, and I would just as soon not go there.

Take an amp, volt and rpm reading. Anything less is speculative. Might be close in some cases.

Selecting the right prop is more than just maxing out the amps or rpms. If there are some amps left to be tapped in your system, another prop may improve thrust and speed. If you are maxed out and want to sacrifice speed for thrust, or thrust for speed, a different prop could do that. Your prop may be almost perfect right now.

Lets say for example your battery can do a continuous discharge at 30 Amps.
Your speed control is rated at 25 amps max
Lets say your motor is rated at 24 amps. [this would be the weakest component and limiting factor]

If you were actualy pulling 22 Amps you would have 2 amps left before maxing out the power system. Then you could decide to keep the pitch the same and go up in diameter to improve thrust, or visa versa.

Hope that helps.
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Old Aug 28, 2006, 04:15 PM
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Hey, i was just showing him the way to calculate prop pitch speed, i agree with slappie that there are too many other variables to actually calculate flying speed. I guess a radar gun would solve that, but then again, is the wind behind you, are you flying level, what's the temperature, Once again too many variables.
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Old Aug 28, 2006, 06:15 PM
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the only problem I see with the above calculations is that they assume 11.1V under load, which may or may not be the case.

It's about a 65-75mph airplane, as far as I can tell. I just put several flights on ours, and I love it. Everything was cool to warm after both flights, the system could be pushed farther. As it is, though, I think it's almost perfect. I never had a brushed Stryker that handled this well. High-alpha inverted is very easy and stable, inverted flight is hands off, loops are tight without any bad manners.

After I get some more flights on it stock, the hot-rodding begins.
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Old Aug 28, 2006, 06:26 PM
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I agree basher, someone stated the the plane was not an 80MPH plane ( STOCK ), yet Parkzone says it is, so i provided a sample prop pitch speed estimating at 11.1v and it still was under 80MPH.
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Old Aug 28, 2006, 07:06 PM
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Yep, and it looks like real-world experience supports your results pretty closely.

2 more flights in the field in front of the 3DHobbyShop warehouse, and I'm loving this one. It'll hang motionless inverted into a 7-10 mph wind (*no* wing rock), and then rocket out with excellent thrust. This is a nice, well-matched power system, with a good balance of thrust and speed.
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Old Aug 29, 2006, 12:46 AM
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Kinda disappointing they have gone for such a low kv motor. I'm running a 3600kv on 3S most of the time and it's a good combination, but speed is noticeably limited by the draggy airframe. Pushing it over 100 needs a lot more power than most wings!

Many others on here are using mega 3t or even 2t, some with 4S. Not sure how much the F27C retails for, but a stock airframe with some of the mods in the stryker threads will ultimately give a better model IMO.

Although this is marketed at the beginner, so it's probably a good starter for ppl venturing into brushless territory.
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