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Jun 03, 2010, 02:00 AM
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Discussion

Stryker Clone w/ pics


After fiddling with Sketchup for awhile and finally finding something that will tile PDFs, I had a go at building a foamy completely from scratch. I've been flying my Stryker F-27C PNP for a little bit now and like it alot. But, of course, that is not the spirit of foamies. gpw, i.e., "Father of Foamies," would not approve. So I went ahead and found some three-views of the Stryker and had at it.

Originally it was intended to have an airfoil, just two layers of blue FFF folded over a spar. But as I began to cut out the parts I liked the idea of keeping it simple. Many less opportunities to screw somethin' up.

I've got three good candidates for power:

- (1.1 oz) a HOT little rewound BW that spins a 6x4 at about 20 amps
- (1.4 oz) Ultrafly D 13/32 3200 KV. rated at 160 watts, but if my BW can
push near 200 I know this can pump out more
- (2.4 oz) Align Trex 420 LF 3200 KV rated at 290 watts and 26 amps

I'm thinking the Align motor is a bit over kill. I think I'll try the Ultrafly motor as long as I can find some screws that will fit the mounting holes.

It has a 30" WS and the airframe weighs in at 2.4 oz.

- Jeff
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Jun 03, 2010, 10:03 AM
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Derek_S's Avatar
Love it. You may have to rework/reshape the nose, as it looks like it will get smoked on belly landings. If it were me I'd put a EPP block carved/sanded to shape on the nose.

I look forward to seeing how you do the access hatch. Those usually have me pondering how to do it without losing too much structural integrity.
Jun 03, 2010, 10:33 AM
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shawn pierce's Avatar
I like it too and was thinking the same thing about the nose. or maby a wire bent down to help save the front. Good job.
Jun 03, 2010, 03:00 PM
Old Prop Buster
Sir Dumb Thumb's Avatar

Cutlass


There is another plane in Foamies Scratchbuilt that looks like a Stryker. It is a EPP Cutlass. Here is the link.
https://www.rcgroups.com/forums/show...hlight=cutlass
Jun 03, 2010, 03:20 PM
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Funny you should mention that one, cause I was actually torn between making a Stryker or Cutlass. I've had a Cutlass in the past and it probably outlasted any other foamy I had at the time. AWESOME flier! It was my Dad's favorite plane to watch fly as well.

- Jeff
Jun 04, 2010, 01:35 AM
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Update:

Installed both servos and linkages. Servos are the original ~9 gram Spektrum S75s that came with my old DX6 years ago...they still seem to work just fine.

I tested the Ultrafly 3200 kv motor with a 5x5, but amperage went up to nearly 30. Then I tried a 4x4.2 which was the next smallest prop I had, and it seems to be perfect at 190 watts and 19 amps.

Might be able to maiden tomorrow if I finish it up as well as another plane that needs its first flight. Just need to fit the electronics, glue the motor mount on, figure out a hatch mechanism, and maybe little paint/sharpy/tape/whatever to help with orientation - should be fast!

I tried a few different motocalcs online and found that the pitch speed at 100% efficiency is something like 138 mph. At 78% efficiency that's 107 mph and 20 oz of thrust. We'll see.

- Jeff
Jun 04, 2010, 01:48 AM
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Here is a link (and another) to those magnets we talked about. Mine just arrived today in the mail and they are crazy strong for their size. With these it shouldn't be too hard to figure something out for your access hatch. I'll be using larger ones to join the wings of my Hawk Sky.
Jun 04, 2010, 02:07 AM
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Yea I found those earlier today after you told me about them as well as some other cheap stuff on dealextreme - love the free shipping! I'll definitely have to get some of those magnets but on this short term notice I'll have to think of something else.

- Jeff
Jun 04, 2010, 06:26 PM
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Well it's going on it's maiden flight right now, as is. I'm gonna keep the top hatch off for now in case I have to move stuff around. Plus, this thing might not even survive it's maiden. We'll see!

- Jeff
Jun 04, 2010, 06:32 PM
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Derek_S's Avatar
Good luck
Jun 04, 2010, 07:05 PM
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At about 10 oz AUW, it was a real floater. Just a few clicks of downtrim and it was flying straight and level. The glide was amazing, but that's not really what I was after. The prop was a little unbalanced, and it was a brand new APC. The prop balancer I have is only for GWS props. Also the OLD 3 cell 1000 I was using wasn't putting out enough juice!

I think the first thing I'll do is balance the prop, somehow, and use a bigger lipo that can handle the amperage. If that gets me some more power, then I'll have to reinforce the wings a little more - probably another layer of FFF or a KF step.

- Jeff
Jun 04, 2010, 07:22 PM
Always Ready!
warhead_71's Avatar
The Stingray is a pretty good Stryker copy... flies really well, much lighter than an actual Stryker.
Jun 05, 2010, 11:19 AM
Registered User
Nice. I want to try make one of theese. Could you please post PDF plans for it ? Good job mate~~
Jun 05, 2010, 01:33 PM
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NorwegianFlyer, I just need to finish up the plans for the box fuse, then I'll post some plans.

I fiddled around last night with the ultrafly motor and tried multiple props, all of them vibrated. At low throttle the props are smooth, at mid to 3/4 they all vibrate, and at full throttle they get smooth again. Really weird! I opened the bell up to see if there were any chunks of metal stuck to the magnets - nothing. I did notice though that there was some weird slop happening within one of the bearings, and I could see how it might be affecting imbalances at different throttle settings. I have a second ultrafly motor that's burnt out so I'll see if I can swap some parts to get it working good.
Jun 05, 2010, 01:46 PM
Registered User
Hmm. I think if u get one of theese: http://www.giantcod.co.uk/221206-220...-p-402397.html

Your plane could do some high speed. And the cost from UK is dang cheap on theese. I started to buy theese instead from graysonhobby due to shipping. And the motors prefer same.

Cant wait till you post the plans. Did you think of which colour you gonna paint it yet?


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