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Old Jan 29, 2006, 12:19 AM
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Michigan
Joined Aug 2002
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F27 Stryker - Lite version

A lot of people are working on mega watt supersonic Stryker variants. But I wondered if anyone has tried it the other way?

I only have a small baseball field here surrounded by trees. No room for a ballistic missile, so I went with the cheap/light approach. I started with an early style bare airframe and used one of the new GWS small outrunners for only $15.00. Nobody likes them because the KV is too high for 3 cells, and can only swing a 7-8 inch prop on 2 cells. Well, a high pitch 6x5.5 prop on two cells works perfect for this plane. Only 9.5 amps on two cells gets me around 10 oz thrust and maybe 75-80 mph pitch speed ( both extrapolated guesses, not measured). The flying weight is only 12.5 oz. so the vertical is surprisingly good when you add some momentum. Won't win drag races with the 300 watt missles, but the speed is respectable and the light wing loading makes it fly like a trainer. A 12.5 oz plane is more durable than and 18++ oz version too.

Seems to have a wide speed range with great tracking at speed and great slow speed manners with no tendancy to tip stall. Not bad for a measly 65 watts,.. makes a zagi look like a flying truck, and its quiet too!! Still handles 15 mph winds, but doesn't have the penetration of a heavier Stryker.

I like it, good looks and performance, cheap airframe, cheap motor and it uses my 2 cell 1320's and PH10 speed control. Just gotta stay away from those plane eating trees.
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Old Jan 29, 2006, 12:58 AM
dst
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Santa Clara
Joined Aug 2005
598 Posts
Some one else here made a light Stryker and posted video. It flew well and looked like a lot of fun. I have a light weight 30" wing that I enjoy much more than my faster wings.

dt
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Old Jan 29, 2006, 01:14 AM
Gotta have more cowbell!!
MTwallet's Avatar
Clawson, MI USA
Joined Sep 2002
2,169 Posts
'Bout friggin time you built that thing!!!
I knew you'd find a way to run it on 2 cells and still be happy with it.

12.5oz is very light indeed, remember my first one? It was 15.5oz but it still had a Mega 4 turn and 3 cells. It got kicked around in the wind a little but not bad enough to complain about, still tracked great. I'm sure at 12.5oz, it's probably a little worse but nothing any intermediate pilot couldn't handle with relative ease.

Where did you get the GWS motor? And, WOW! Only $15?? Looks like the price wars with all the BL motor makers will be on big time this Summer (I hope).

I just checked AlleRC
It looks like that motor has a 1300Kv. I am really surprised that you are even drawing 9.5A on 2 cells with the 6x5.5 prop.

I had that Aurora 400T (1300 kv) in my Ultrafly BAe Hawk on 3 cells and a 7x7 prop. It drew 10A, that plane was 53mph according to doppler radar. I then put that same setup in my Lil' Rascal and you saw that. It looked like a Pylon racer, doing close to 65 or 70mph. Still only drawing 10A on 3 cells.
Maybe this is why the GWS motor is only $15 and the 400T is $50.

Anyway, glad you're having fun with your Stryker (FINALLY), Nice motor mount by the way, you make that where you are at or are you back in town now?


MT
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Old Jan 29, 2006, 07:16 AM
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Alpharetta, GA
Joined Sep 2004
460 Posts
Any chance of trying with a 3 cell and a 6x4 prop.

Gws says these motors can handle 4s at 10amps too. I might buy one and see how far I can push it!
BTW< it is a 2000kv motor, not a 1300kv one.

Kevin
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Old Jan 29, 2006, 10:13 AM
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Michigan
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MT,.. I'll be in the sunny south till May. I hear you guys are having decent weather for Jan. If global warming would hurry up, I wouldn't have to migrate.

I had big plans for a 2 cell hotrod, but got lazy once I found this cheap motor at an event down here. I wanted to push a razor to maybe 110 watts but direct drive meant tiny props, and even the fastest gearing was too slow to get me the pitch speed. The GWS is $15.00 full retail, so imagine when they start getting discounted. The outside is real quality with CNC ends and replacable shaft, easy mounting. The KV is still being debated, but everyone agrees its not the best performer with weak magnets, big airgap, funky winds with small wire atc. It looks like a great motor to rewind though. There's room for more windings, and thicker/stronger magnets will fit?

I also planned to work over the airframe,.. maybe clip the wings, use shorter paper thin carbon fins, balsa elevons, remove side scoops, fair in the linkages etc, etc. Again, I got lazy and just carved away the fakey side air scoops and tucked in the motor a little better. Plenty fast for my small space here.

The motor mount is a thin aluminum wall outlet cover plate from the hardware store disquised as an airplane part. It fits into a slice in the foam and has a "finger" that extends forward inside the fuse. little tabs bend down to push on the trailing edge, and bend up for the motor.

AV8TR... I read that GWS says 8 amps on 3 cells and these motors go down to 50% efficiency when pushed any harder. Any motor will run cool with good cooling, so that's not the limitation, but efficiency plummets. I think a 6x4 would be too much on three cells, but a 5 by something should work? I don't have any 3 cells 1320's to try.
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Old Jan 29, 2006, 10:20 AM
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Michigan
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AV8TR,.. just re-read your post, and noticed you said 4s!!! that's way too much for a 6x4. Theres a good thread on this motor in the power system forum. I think you would have to rebuild it and may as well start with a better choice?? Then again, somebody has to find the limits, push it till it blows, then rewind it?
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Old Jan 29, 2006, 10:54 AM
Gotta have more cowbell!!
MTwallet's Avatar
Clawson, MI USA
Joined Sep 2002
2,169 Posts
Quote:
Originally Posted by aV8ter
Any chance of trying with a 3 cell and a 6x4 prop.

Gws says these motors can handle 4s at 10amps too. I might buy one and see how far I can push it!
BTW< it is a 2000kv motor, not a 1300kv one.

Kevin
I did some more checking and you are right, there is a 2050Kv motor and a 1050Kv motor. Kayaker must have the 2050Kv unit. That would explain why I thought the amps were too high on 2 cells comaired to my 400T on 3 cells.

I don't think a 6x4 on 3 cells would be anywhere within the limits of this motor, probably close to 20A I guess since that's about what a Mega 4 turn draws with that setup. On 4 cells, you'd probably have to run about a 3 inch prop to keep the amps down. If you try it, post it so we will know what you find.

Hey Kayaker, I was wondering... Is the performance any better than stock? I mean in the speed and climb catagory? If so you might have a real winner there, even if it's the same performance as stock.
It sounds to me like you could put one together like yours for under $200 all you'd need is a cheapo Tx and ya got a Stryker that can take crashes MUCH better than stock. At 12.5oz, it's about 10oz lighter than stock, it would be WAY easier to learn on since it could fly slower with the lighter wing loading and have less inertia if/when it does hit the ground in a crash.

Hmmm, might be a market for that. There have been others putting together BL Stryker packages and selling them.


MT
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Old Jan 29, 2006, 08:55 PM
Fish & Fly
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Tyler, TX USA
Joined Jul 2000
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During the holidays, I built a very similar "Stryker-Lite" out of the same $19.95 white foam fuselage, balsa fins and elevons, etc.

Mine with a Dualsky Xmotor 300B Outrunner (weighs 44 grams, spins a GWS 8x4 very well for about 21.5oz of thrust) and 3S 2000mah lipos comes out to 18.3oz AUW (12.8 oz without the pack). I could probably get it a bit lighter by using 55s instead of the HS-81 servos I have in there now. I'm also looking at trimming away the air scoops too, but I don't think that will knock the weight down very much. Mine is unpainted, but the fins and elevons are covered.

I've done a few test flights with it and was pretty impressed. It's not a speedster (I have a 16/15/3 Mega Projeti for that - it needs a BIG field), but I pulled an 80 degree climb at takeoff of the second test flight a few weeks ago. Further test flights had to be suspended because my old FMA Rx (which had been sitting in my "leftovers" box) was picking up significant interference in one area of the park where I fly and I decided to not use it on the Stryker any more. Hopefully, a new crystal for my Berg Mini 6 is on it's way from RC-Direct and will get here soon.
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Old Jan 29, 2006, 10:51 PM
Gotta have more cowbell!!
MTwallet's Avatar
Clawson, MI USA
Joined Sep 2002
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Quote:
I'm also looking at trimming away the air scoops too, but I don't think that will knock the weight down very much.
No, it doesn't much effect on the weight but it does do wonders for inflight drag, especially if you are flying faster versions like I do.
Some guys leave them and hollow them out to the battery compatment to allow for cooling air to get to the batteries.


MT
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Old Jan 30, 2006, 11:31 AM
CARL T
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United States, OR, Grants Pass
Joined Dec 2005
395 Posts
Kayaker 43,
Very nice work on the Stryker. CLEAN looking.
Would you please put up a sketch of your motor mount and how it is fitted into the airframe. What ESC did you use? What method did you use to cut the scoops off with? The rest we can figure out.
Thanks.
Carl
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Old Jan 30, 2006, 01:37 PM
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anaheim, ca
Joined Apr 2005
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for cutting off scoops just use a sharp knife (exacto) and maybe a straight edge. for hollowing to allow cooling you can use a soldering iron to melt the holes in. the mount looks good.
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Old Jan 30, 2006, 05:43 PM
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Michigan
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I've got the GWS 2205-16 motor. I'm using older gen2 TP1320's and they actually get fairly warm at 9.5 amps. They also start sagging in about 5 seconds but rebound fast. I need to get some newer pro-lites and I'll bet I pick up another amp or so?

I never saw a stock Stryker fly,.. just the hot rods. I would think its as fast but probably a bit faster than stock. If you fly low and real slow, then hit throttle and pull vertical it runs out of steam in 100 yds with less thrust than weight. If you do a fast pass and pull up it goes a loong way up with time for maybe 4 rolls. How does that compare to stock? I thought a speed 400 only had about the same thrust as this motor but gobs more weight, so it may build more speed in a dive? This one is pretty quiet with a pleasing whine. I HATE the zagi scream, so this would be better for flying in parks etc.

I posted some pics of the mount. I cut away the rear part of the wing to move the center part 3/4 forward, then tapered the edge to match that ailerons angle. This was an attempt to move the motor forward to help with anticipated CG issues. The battery ended up midway between the front two canopy sections. The sketch shows the layout and tabs, but no dimensions are critical. I used a med hard .050 alum sheet. I laid a template on top of the second photo to show how the mount extends forward inside the fuse for stability. I used Goop to secure it and cut the slot with a long utility knife blade. An aftermarket stick mount for eps 300 motor would work OK with an embedded stick too. I dropped the motor behind the fuse so the top half sticks up for cooling and I can still get to the screws. The other thought was to glue the mount on the bottom wing surface to put the motor lower. It runs cool, so I could have done that?

I cut the scoops off the normal way. Take the long blade out of a disposable utility knife to make it more dangerous. Then carelssly hack away while simultaneously butchering your favorite fingers. Wipe the blood spatter off the ceiling then sniff some CA until the pain stops. (Kidding )

Everytime I try to fly it rains,.. I think I built a rain machine? I have the CG 13mm in front of the center of the handholds. It needs an initial shove forward when going inverted, then light pressure to hold it. I may try moving it around. I'm also trying different throws. It takes a lot of throw for a decent roll rate, and much less on the elevator. Although you lose control authority at slow speeds, I still havent been able to make it stall or do anything bad. The low wing loading makes it fly like a puppy. The rudder just sucks,.. I mean its like its not even there Seriously, I wondered about adding rudder to one fin?? Knife edge is weak too

Has anyone messed with differential ailerons? At speed with small deflections there's no adverse yaw but going slower you get some as you would expect.

My typing finger is starting to cramp..
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Old Jan 30, 2006, 06:28 PM
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Michigan
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Carl T,.. sorry I forgot, for speed controls I tried a CC10 and 25 thinking the 25 would have less voltage drop with bigger wires etc. It turned out the 10 amp control was slightly more efficient . I stuck the bigger 25 in anway because I needed the 10 for another plane.

Theres'a agood chance a newer 1320 prolite or larger battery may draw over 10 amps with the 6 x 5.5 prop. My gen2 batteries might be getting tired after a couple seasons?
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Old Feb 04, 2006, 09:11 PM
flutter!
MichaelConnally's Avatar
TX
Joined Jul 2002
2,112 Posts
I just finished my new stryker lite. AUW 11oz and about 18-20oz of thrust.
pico servos
6mm depron elevons, vertical stabs, and fuse cover
gws Rx
cc 10
cd-rom
7X3.5
3 cell xpower 1050's

It's slows down very well and has plenty of vertical.

Mike
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Old Feb 04, 2006, 10:21 PM
Fish & Fly
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Tyler, TX USA
Joined Jul 2000
1,406 Posts
Got the radio issues all cleared up on my "Stryker-Lite" earlier this week and had a chance to fly it some during the past few days.

Speed is good. Climb is darn close to vertical. It would probably hold straight vertical if I didn't have the control surfaces set for fast rolls (right now, it's tough to hold steady when motor torque becomes a factor and the plane gets harder to see). I'll have to set up dual rates for next time. Maybe that'll help some.

I've yet to notice any bad flight tendancies for the Stryker-Lite. Launching is easy with a little up trim. Power-off stalls are a non-event. Approaches and landings are straightforward and it has a fairly predictable glide path.

My 14-year old son, after watching it fly, commented, "That thing's awesome!" He understands that he'll have to get more stick time on our "beater" Zagi before he gets a shot at this one.
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