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Old Mar 17, 2008, 03:23 PM
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Kev71H's Avatar
San Jose, California, United States
Joined Apr 2002
3,705 Posts
Quote:
Originally Posted by GryphonRCU
brian94066,

For the last 30 years I lived in San Francisco bay area. Recently I moved to NC for a job that didn't last.
If I can find a job in the semiconductor industry again, I'll be moving to San Jose area again. I loved working there before.

We may get to fly our Strykers together.

Also I don't mind people flying my Stryker because the Co-pilot makes it gryphon proof, I mean goof proof...

I read a bit of smack from some Funjet owners in the past. Guys who switched over from Strykers. I would love to see the expression on their face when my Stryker blows past their modified Funjets. Where is their loyalty? If they had never owned Strykers then their talk wouldnít get to me. Nothing to worry about, just a little pet peeve. Each plane should be enjoyed for what it is but should not be put down. Not even worth another post

Gryph
I work in the Semi Conductor industry here in the bay area CA....what do you do? We Make Jfets and switches (took over some Siliconix lines too.
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Old Mar 18, 2008, 12:55 PM
Registered User
Joined Sep 2006
110 Posts
Question for anyone--I currently have a scratch-built stryker with a mega 16/5/5, APC 7x5E prop, 40 amp ESC, running on a 3S 2250 lipo. Climb is great but I would like more speed if possible. Do you think changing to an APC 6.5x6.5 would provide a noticeable increase in speed? How about a 7x7, 7x8, or 7x9? Any advice would be appreciated!

Thanks!
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Old Mar 18, 2008, 02:54 PM
Crash Test Dummy
e2346437's Avatar
United States, ME, Mapleton
Joined May 2005
907 Posts
Quote:
Originally Posted by Erick88
Question for anyone--I currently have a scratch-built stryker with a mega 16/5/5, APC 7x5E prop, 40 amp ESC, running on a 3S 2250 lipo. Climb is great but I would like more speed if possible. Do you think changing to an APC 6.5x6.5 would provide a noticeable increase in speed? How about a 7x7, 7x8, or 7x9? Any advice would be appreciated!

Thanks!
Make your prop smaller to take advantage of higher RPM's, or raise your cellcount.

The Stryker battery bay will take a 4s 2200 lipo pack from HobbyCity.com perfectly.
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Old Mar 18, 2008, 04:45 PM
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United States, CA, SF
Joined Mar 2008
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Kev71H,

Thank you for the post. I will try to send you a PM today or tomorrow. Today has been a crazy day.

It would be great to meet you in person one day.

Chat with you later.

________________________________

Erick88,

I've made a Stryker Airframe in MOTOCALC which helps me simulate various combinations well. Often it has come to within 1-3 MPH of my actual radar readings, even with a WEMOTEC MINI 480 fan on my best friendís Stryker at 100 MPH.
The Airframe is going to be shared with one guy only in about a month from now (there is a reason for it)...

Anyway:
I 100% agree with you about switching over to a 6.5X6.5 prop such as APC Pylon series.
It shows that you will pick up a solid 5-6 MPH without a huge loss in climbing (maybe 15% loss).
_______________
From personal experience I know that the APC E 7X5 draws similar to APC sport (GAS) 7X7 while on ground.
That 7X5 produces more thrust at low speeds and has better climbing.
It unloads AMPS as you approach higher speeds, but 7X7 does not unload much at all so it flies faster at a cost to climbing and run time compared to 7X5.
Simulation shows the 6.5X6.5 to not be far behind 7X7 as far as climbing goes AND they have the same speed. That is an indication that the motor cannot produce much more power and it is getting maxed out. The efficiency drop backs that idea up well.

I would not go much further than 6.5X6.5 because the gains ďif anyĒ will most likely not be worth it.
Personally I would also test 7X7 with wattmeter and tach and then in flight.

Nice things about APC sport series is they draw fewer amps given similar sized ELECTRIC props, and that they allows us to go to larger sized props than we could have done otherwise.
Keep an eye on motor temp and run a heat sink if needed.
If it runs slightly hot don't worry. Check the motor temp again in warmer weather.
Good 28mm heat sink is available from Align (snaps on).
___________________________
Your bottle neck while on 3S is your motor.
Your higher resistance value compared to resistance of higher KV motors does not allow you to push as many Amps. Your motor can shine with higher voltage.
___________________________
Not sure of your ESCs max voltage specs.

But your motor can benefit from 4S, 5S, 6S.
Even on 6S it is not going to be above max voltage specs for that motor (benefit of lower KV motor compared to higher KV motors).
On 6S you are within voltage and RPM limits of your motor.
Keep amps in check with correct prop size. For 16/15/X series stay below twice MEGA's SUPER conservative AMP ratings.
We run 16/25/X at 2 to 2 1/2 times amp rating and they don't run hot and do perform really well and take no damage. (We have pushed harder than that too).
__________________
Let your charger limitations and battery weight for you flying style be your guide in selecting possible higher voltage battery.
For your needs, you might need to push a future "Heavier pack" further back for better C.G.
You can run (2) identical 3S packs that are in similar condition as 6S (wired in series). This is done in 120MPH Strykers all the time and will easily ensure little over 100 MPH with your setup.

Right now, you are probably close to 70 MPH. Ever tested the speed?


You left out your battery "C" rating, but I presumed at least 20C.



Have fun,

Gryph
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Old Mar 18, 2008, 09:06 PM
Registered User
Joined Sep 2006
110 Posts
Quote:
Originally Posted by GryphonRCU
Kev71H,

Thank you for the post. I will try to send you a PM today or tomorrow. Today has been a crazy day.

It would be great to meet you in person one day.

Chat with you later.

________________________________

Erick88,

I've made a Stryker Airframe in MOTOCALC which helps me simulate various combinations well. Often it has come to within 1-3 MPH of my actual radar readings, even with a WEMOTEC MINI 480 fan on my best friendís Stryker at 100 MPH.
The Airframe is going to be shared with one guy only in about a month from now (there is a reason for it)...

Anyway:
I 100% agree with you about switching over to a 6.5X6.5 prop such as APC Pylon series.
It shows that you will pick up a solid 5-6 MPH without a huge loss in climbing (maybe 15% loss).
_______________
From personal experience I know that the APC E 7X5 draws similar to APC sport (GAS) 7X7 while on ground.
That 7X5 produces more thrust at low speeds and has better climbing.
It unloads AMPS as you approach higher speeds, but 7X7 does not unload much at all so it flies faster at a cost to climbing and run time compared to 7X5.
Simulation shows the 6.5X6.5 to not be far behind 7X7 as far as climbing goes AND they have the same speed. That is an indication that the motor cannot produce much more power and it is getting maxed out. The efficiency drop backs that idea up well.

I would not go much further than 6.5X6.5 because the gains ďif anyĒ will most likely not be worth it.
Personally I would also test 7X7 with wattmeter and tach and then in flight.

Nice things about APC sport series is they draw fewer amps given similar sized ELECTRIC props, and that they allows us to go to larger sized props than we could have done otherwise.
Keep an eye on motor temp and run a heat sink if needed.
If it runs slightly hot don't worry. Check the motor temp again in warmer weather.
Good 28mm heat sink is available from Align (snaps on).
___________________________
Your bottle neck while on 3S is your motor.
Your higher resistance value compared to resistance of higher KV motors does not allow you to push as many Amps. Your motor can shine with higher voltage.
___________________________
Not sure of your ESCs max voltage specs.

But your motor can benefit from 4S, 5S, 6S.
Even on 6S it is not going to be above max voltage specs for that motor (benefit of lower KV motor compared to higher KV motors).
On 6S you are within voltage and RPM limits of your motor.
Keep amps in check with correct prop size. For 16/15/X series stay below twice MEGA's SUPER conservative AMP ratings.
We run 16/25/X at 2 to 2 1/2 times amp rating and they don't run hot and do perform really well and take no damage. (We have pushed harder than that too).
__________________
Let your charger limitations and battery weight for you flying style be your guide in selecting possible higher voltage battery.
For your needs, you might need to push a future "Heavier pack" further back for better C.G.
You can run (2) identical 3S packs that are in similar condition as 6S (wired in series). This is done in 120MPH Strykers all the time and will easily ensure little over 100 MPH with your setup.

Right now, you are probably close to 70 MPH. Ever tested the speed?


You left out your battery "C" rating, but I presumed at least 20C.



Have fun,

Gryph
Thanks for the detailed reply. That was the other question I had that I forgot in the original post--would a 4S battery help? Obviously it would, but based on your advice I'll definitely still order a 6.5X6.5 APC to try out.

My charger (celectra) only charges 1-3 cells...SO...what I was thinking about doing is ordering 2 @ 2S 1800 mah 20 C Loong Max batteries from value hobby(yes, my current batt. is 20 C) and connecting them with one of these:
http://www.hobbycity.com/hobbycity/s...idProduct=2156

that I can make with dean's connectors and quality wire. Together they only weigh about 0.6 oz. more than my current 3S 2250. With the right prop (which would you recommend?), I would think that this set-up should give me more than enough speed to last me for awhile--famous last words, right??!!!
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Old Mar 18, 2008, 09:32 PM
Ebolavoodoo's Avatar
United States, CA, El Cerrito
Joined Jan 2007
1,118 Posts
Quote:
Originally Posted by glucoseboy
If you're going to the trouble of glassing the stryker, you might as well do the whole thing. If you're concerned about strengthening weak areas, then the tape reinforcement as described in the previous posts would be you're best bet (in my opinion)
Everyone knows Strykers have a somewhat draggy airframe. I was considering sanding down the wings and body, making them thin, then glassing the whole thing. It would have a thin, yet strong wing, with rod still in place, as well as a streamline body.

I'll start a thread if I decide to do so.
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Old Mar 18, 2008, 10:13 PM
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GryphonRCU's Avatar
United States, CA, SF
Joined Mar 2008
3,870 Posts
Erick88,

Wait a minute....Is this the same Erick88 that ran the brushed Graupner 6304L back in Dec 06? If so I still have your old PMs.

Edit; I added "L" to end of model number above. Means reverse rotation, correct for Stryker.

_____________________
Expect 10 MPH gain on 4S.

I was going to talk smack about the 1800 sized cell, but they should actually get the job done fine. If you prop for 30-32A they can handle just fine.
You will end up at about 85 MPH.

Since you are going to order an APC Pylon 6.5X6.5 for your 3S, Go ahead and get a 6.5X5.5 and 6.5X5.0 at same time.

The last two props will have about same speed on 4S. Those two props will also be similar to 6X5.5 as far as speed, but the 6.5" props will have better climbing.

I vote for 6.5X5.0 and a wattmeter reading.

Extra 2 MPH (3 max) possible from other props can't make up for the fun factor of this propís added climbing capability.

One thing that I learned and most of you will disagree with is that weight is my friend. The heavier the birds got the more fun I had and the less the wind affected me and the faster I flew. Each person has a different taste.

Don't worry about a little battery weight. Although you donít have a need for bigger than 1800 cells to flow the required amps, I suggest bigger cells for longer flight duration.

If you flow more amps than before and you have smaller cells, your flight duration will be reduced by a whole lot more than you will be expecting. I'm afraid you will not be happy with your flight duration.

Who cares if you have an extra ounce or two in battery weight...I don't think you will be yelled at.
If they knew about my battery, I would be yelled at. You are safe.


Have fun,

Gryphon
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Old Mar 18, 2008, 10:28 PM
If it floats....sail it!
FoamCrusher's Avatar
Elk Grove, CA
Joined Sep 2002
4,188 Posts
Quote:
Originally Posted by Erick88
Question for anyone--I currently have a scratch-built stryker with a mega 16/5/5, APC 7x5E prop, 40 amp ESC, running on a 3S 2250 lipo. Climb is great but I would like more speed if possible. ..... Any advice would be appreciated!
Switch to 4S packs with a 6x4 and hold onto you seat. Just remember at 4S voltage you will need a separate BEC as the ones in most ESC's cannot deal with that much voltage.

FC
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Old Mar 19, 2008, 12:05 AM
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Joined Sep 2006
110 Posts
Quote:
Originally Posted by GryphonRCU
Erick88,

Wait a minute....Is this the same Erick88 that ran the Graupner 6304 back in Dec 06? If so I still have your old PMs.

_____________________
Expect 10 MPH gain on 4S.

I was going to talk smack about the 1800 sized cell, but they should actually get the job done fine. If you prop for 30-32A they can handle just fine.
You will end up at about 85 MPH.

Since you are going to order an APC Pylon 6.5X6.5 for your 3S, Go ahead and get a 6.5X5.5 and 6.5X5.0 at same time.

The last two props will have about same speed on 4S. Those two props will also be similar to 6X5.5 as far as speed, but the 6.5" props will have better climbing.

I vote for 6.5X5.0 and a wattmeter reading.

Extra 2 MPH (3 max) possible from other props can't make up for the fun factor of this propís added climbing capability.

One thing that I learned and most of you will disagree with is that weight is my friend. The heavier the birds got the more fun I had and the less the wind affected me and the faster I flew. Each person has a different taste.

Don't worry about a little battery weight. Although you donít have a need for bigger than 1800 cells to flow the required amps, I suggest bigger cells for longer flight duration.

If you flow more amps than before and you have smaller cells, your flight duration will be reduced by a whole lot more than you will be expecting. I'm afraid you will not be happy with your flight duration.

Who cares if you have an extra ounce or two in battery weight...I don't think you will be yelled at.
If they knew about my battery, I would be yelled at. You are safe.


Have fun,

Gryphon
Yup, I'm the one who tried the graupner--and it worked really well until I screwed up and let the magic smoke out of the motor!!

Sounds like the 4s should work well--maybe I'll go with the 2250's when I save up some more cash. In the meantime if I can gain another 5-6 mph from the 6.5X6.5 that may last me a little while. It's finally almost flying season here in Ohio!
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Old Mar 19, 2008, 12:08 AM
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Joined Sep 2006
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Quote:
Originally Posted by FoamCrusher
Switch to 4S packs with a 6x4 and hold onto you seat. Just remember at 4S voltage you will need a separate BEC as the ones in most ESC's cannot deal with that much voltage.

FC
My ESC has a 5V/3A switch mode BEC so I'm thinking I'll be fine to run 2 servos on 4S (or at least the instructions say so)!!
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Old Mar 19, 2008, 12:34 AM
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GryphonRCU's Avatar
United States, CA, SF
Joined Mar 2008
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Erick88,

Can you please tell me how long the motor worked for you?

And if you ever took reading of any type from that motor.

What did you normally run for battery and prop?

So what lead to the motor smoking?
I'm only asking this so I can take it into account for future recommendations.

Ever changed the replaceable brushes on that brushed Graupner 6304L motor that Hobby-Lobby sells for $29?

I would appreciate whatever you remember, and feel free to PM me instead of a post if you prefer.

__________

Personally on 2 occasions I took a fairly new stock 480 brushed motor and figured out what it took to smoke it on 3S.


Later,

Gryph
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Old Mar 19, 2008, 04:24 AM
zoom zoom
gotboostedvr6's Avatar
USA, NJ, Mt Laurel
Joined Oct 2007
3,691 Posts
So i got bored with the stock stryker airframe and did some cutting. ill maiden it tomorrow and tear it down for a respray but it looks like it will fly very (wing like) now . I did this complete job in 1.5 hr including completely cutting the fuse in half and adding carbon rods... i need to think of something for the motor mount but it will hold temporarily...



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Old Mar 19, 2008, 05:45 AM
Ebolavoodoo's Avatar
United States, CA, El Cerrito
Joined Jan 2007
1,118 Posts
Gotboosted,

That planes got some miles on it fo sure!!! Keep on truckin!!!
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Old Mar 19, 2008, 07:47 PM
zoom zoom
gotboostedvr6's Avatar
USA, NJ, Mt Laurel
Joined Oct 2007
3,691 Posts
here are some more build and almost finished pics. i flew it today before i painted it and wow... talk about fun to fly





----



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Old Mar 19, 2008, 10:08 PM
VBARRRR
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USA, CA, San Bruno
Joined Jul 2007
2,502 Posts
are you sure that's a stryker?

cuz it sure doesnt look like 1
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