moparmyway

Critterhunter,
If my vote counts, I vote you fix the Stryker sooner rather than later........................You dont know it, but you have greatly inspired alot of us Stryker freaks, especially me...........................so THANKS !!!!!!!!!!!!!!

alexbent

wow, thanks for all the pictures

critterhunter

Thanks to both of you. I'll get to fixing the streamlined Stryker soon enough, before spring anyway. Here's my latest scratch built design, a glider hotwired from EPS. It should do unlimited V with the 48 ounces of thrust. Wingspan is 6 feet. Details in the foamie forum under the thread "Here's A Simple And Free...". What can I say, it's much more fun building new homemade designs from scratch than fixing crash damage on planes I've already flown. When you hotwire foam you can pretty much create anything you can imagine. Next will be a bird of prey that will use many of the Stryker mods found here. I'll throw up pictures of it when done.

critterhunter

My latest scratch built EPS bird, a bird of prey. Nothing glued or anything yet but the motor is on and a carbon tube is already in the wing. I'm using Don's KA450H motor which should really get this bird moving. This is a popular motor among Stryker owners. This plane will use many of the mods I've learned from building Strykers.

The dirty side of the fuse is due to me using what was once "scrap" foam to test a spray paint on. I hate waisting foam so rather than throw it out I used it for the fuse.

Wingspan is about 44" or so, using a USA27 airfoil that has been heavily sanded down to thin it further, so it's probably closer to a RAF. 8 1/2" at the root. Controls will be elevons only. Not sure where I'm going to put the v-stab(s), on top or bottom of the wing near the root somewhere.

My main concern right now is figuring out the proper COG location for this plane. I normaly like to test throw a platform with no electronics in it when I can't do the math for the COG because the wing isn't conventional. A friend told me that birds of prey don't really test glide so I guess that's out. I'll have to read a few threads on birds of prey with similar wings to take a guess at where I need to start with the COG. If anybody cares to use the picture to judge the sweep of the wing and take a guess at COG I'm all ears. I've heard some birds of prey want it at about the wing tips, while others say about a half inch in front of the leading edge at the root.

critterhunter

A friend who's built a few birds of prey told me he thinks the COG should be about 2" in front of the leading edge of the root. That's pushing it as far as the short fuse length goes, but I'm doing a number of things to compensate.

The fuse was a good 4" longer until I botched the cut. But, I've got an ace in the hole. I'll be lining the battery chamber with ply, making the battery cover out of basswood rather than balsa for more weight, and adding my usual four magnets to hold the battery cover on. I'll also be mounting the servos and other hardware as far forward as possible. The motor is moved up under the wing. The wing tube is also way up front and I may fiberglass the leading edge.

I figured I'd probably have to add some nose weight even with all that, but it should reduce the weight required. My final mod before adding nose weight may be to square off the front end, then add a detachable nose held on via magnets. Always liked doing that on my Strykers to absorb crash momentum, and if the nose gets crushed you just cut out a new one.

I completed sanding the fuse and sheeting it's sides with balsa. Motor is mounted. Dowl rod is sunk into the fuse and tapped for nylon bolts. Ply sunk into the wing to avoid the bolts pulling through. Elevons are hinged and carbon tubes have been added to them for strength.

I was wrong about the root, it's 8" and not 8 1/2. I'll have to measure the wingspan, but after some cutting and sanding it's probably in the 40 to 44" range. I'd still prefer some input on where the COG should be. Anybody agree with the 2" forward?

critterhunter

Have to do a correction on the build instructions concerning servo linkages. I always use to set my planes up with the control rod in the top hole on the servo and the bottom on the horn to give most throw, then lower the rates to compensate. There are two reasons why this is not a good idea. For one, this linkage setup puts the most stress on the servo, increasing the chances of stripping it, and you are not taking advantage of the leverage available. The second reason why it's a bad idea is you lose resolution or "feel" for the servo's travel. It makes the controls much more twitchy.

After blowing the elevator servo on my AP plane twice I decided to do a little research. I knew of people using this servo (HXT900) in much bigger, faster, and heavier planes with no problem. Turns out that the exact reverse in rigging is what I needed to do. I now put the control rod in the second hole down on the servo and in the very top hole on the Great Planes small horns I use for most of my builds. This makes it much easier on the servo and also gives you much more feel for what the control surface is doing.

Now I know why a friend's planes felt much smoother and more in control when I flew them, since this is how he rigs his servos up. All the time I've spent in this hobby and never really investigated proper linkage setup until now.

tam popo

Critt - The HXT900 (or Hextronic servos) are ceramic geared (therefore less prone to stripping) and not plastic like TPro etc. The only ones I use now and same price etc.

critterhunter

The HXT900 from Hobby City is what I'm refering to. For $4 you can't beat the price. They are stronger than Hitec's HS55 servos and strip less, not to mention being 1/4th the price. I've seen these servos used in situations where you'd think an HS81 would be needed, yet they hold up to the beating. In fact, I'd probably trust this servo in a Stryker if I didn't have any HS81s laying around. It's become my "universal" servo for builds big, fast, slow or small for the most part.

tam popo

Looks like we have both seen The Light!!!!! I'm now on building my 4th Slow Stick, mainly 'cos of eyesight and lack of reflex action, but it doesn't stop me fitting a 250W motor to it!!!! Its a pigeon killer....easily.

jmir

My Feedback: (1)

Does Hobby City have a direct replacement for the HS81's ? These are slightly larger than the HS55, so HXT900 would not work as well.

critterhunter

The HS81 is a bit bigger, but you'd be suprised to see where the HXT900 has been used on builds where I thought the HS81 was a must. Hobby City did have a good replacement for the HS81, I think it was the 9320 or 9314 or something like that. They featured metal gears and sold for about $12 or so. All the reviews I've read over the past year of these servos say that they are complete junk now, having switched the components in them. If you really don't trust the HXT900 for a heavy duty job then I'd say use an HS81. Come to think of it, I think they've replaced the HS81 with a nearly identical servo. Let's hope the pots in it are better, as I've got a pile of HS81s that act up because of bad pots, despite cleaning them.

tam popo

Guys - the replacement for the HS81 is.....(drum roll!!) - the HS82. And obviously ask for MG (Metal Gears). I think the HXT's hve replacement gear sets available as well. Hope this helps.

critterhunter

I finally bought a new Stryker body and am building a new bird. I figured that it'd be a good idea to close this thread and start a new one with the build steps. Much of these are the same mods and build steps that were found in this thread, but as most people know I tend to ramble on. For this reason I'm starting the new thread and will try to keep to the point with the provided info in order to help Stryker owners build a "bullet proof" Stryker with ease of use mods as well that make it easy to service the bird in the field. New thread can be found here...

http://www.rcuniverse.com/forum/m_86...tm.htm#8631014

ProVluvR

Thanks CH
Will use much of this info next week when I begin the build of my first Stryker.