Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

Need shrike advice

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Old 09-18-2003, 11:59 PM
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schmleff
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Default Need shrike advice

yes I searched.

I noticed that the vertical fins are mounted at different angles on the pictures I saw. Has there been any difference in the way they fly? If it is all the same, mounting them straight up seems best to me.

Just secured a OS .32 heli motor with pipe for it. Wings are getting mods and all of the other go fast overpowering jazz is being done. Should be done in a few weeks.

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Old 09-19-2003, 12:17 AM
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Default RE: Need shrike advice

Oh ya,

Flaperons, anyone using them on a shrike?

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Old 09-19-2003, 01:50 AM
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Default RE: Need shrike advice

The fin angle won't make a heck of a lot of difference in any aspect, they aren't canted out much anyway. I canted my fins inwards a long ways on my first Kangaroo vs the stock straight up vertical fins and it didn't make any real difference at all.

As for flaperons, I don't think they would do much of anything except make it really twitchy. The ailerons are very close to the elevator (short coupled) and I just think you'd probably be asking for problems. The plane will slow down really well as it is, just keep the nose up for landing. It's basically a delta more than anything. I got mine pretty slow, only downside was mine is pretty nose heavy right now so it's lacking in elevator authority right now.
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Old 09-19-2003, 06:57 AM
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Default RE: Need shrike advice

I have also read accounts of shrike's being destroyed due to the elevator servo not having enought power to pull out of a dive. I have another go fast plane with a single standard elevator servo but have never had a problem with it.

Do you think that the problem could be the wimpy control wire? I have aluminum arrow shafts in my other plane and would never have considered of using the wire that the plans show (when overpowering), especially with a bend in it half way to the control surface.

I have an extra arcamax gyro that I might put on the elevator to make it less pitch twichy too.

Thanks in advance for the advice.

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Old 09-19-2003, 09:01 AM
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Mike Connor
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Default RE: Need shrike advice

I have seen several post where people used different fin angles on the Shrike including having the fins angle inwards. There were no complaints on how it flew. I used a table saw to get the correct angle so they would be exact on both sides.

I also used the "wimpy control wire" on mine with out problem. Mine did not have a bend in it and was supported mid way by the extended hatch. Up would be pulling so there is no way it could flex. I also used standard JR 517 BB servos with out problem but would probably use a stronger and lighter servo next time. Mine was powered by a Sport Jett engine. Pictures and videos on my site.
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Old 09-19-2003, 11:15 AM
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Default RE: Need shrike advice

I have had both the fins inwards and out. I saw no difference. I also have used standard servos on my .32 powered one with no problems. How do you add pictures to this new site. I can't get it to work.[:@]
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Old 09-19-2003, 12:09 PM
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Default RE: Need shrike advice

I have been flying my 32SX powered Shrike 10 for 2 months now. While I have never had a problem hand-launching it, I have had my share of both smooth landings and hard,fast, not-so-smooth landings! Hey, bleeding off speed from 145 mph to zero can be tricky when you're dead-sticking it into a small patch of grass!! One item that became immediately obvious was that the bottom TE corners of the fins are a definite weak spot. They're hanging down and are often the first thing to touch ground on landing, so they will break and crack on ya eventually. All Shrike owners will know what I'm talking about.

The little copper wire they want you to add as fin skids is just worthless. Drilling the hole to attach it just creates a weak spot in the balsa, even when filled with epoxy. I ended up adding 1 inch strips of carbon fiber to both sides of each fin corner, plus along the whole vertical trailing edge to give it some needed strength.

If I were to do it again, I think I would just wrap the fin bottom corners in glass cloth and be done with it.

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Old 09-23-2003, 02:22 AM
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Default RE: Need shrike advice

I think the elev. failure on the Shrike is an aerodynamic failure. I have flown the mid size and the 40 size, and both had a real problem at low speed, you just could not let them slow down. It is just a design flaw, it is too bad cause the plane looks so good !

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Old 09-23-2003, 06:43 AM
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Default RE: Need shrike advice

I think I am going to try mixing some flaperon into the elevator. Also, it sounds like most of the overpowered ones come out nose heavy which would lead to them not slowing down very well.

I am going to put a 6v pack in the back of the plane to try and help with some of that. Also moving the servos as far back as possilbe.

Thanks for the info.

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Old 09-23-2003, 07:55 AM
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Default RE: Need shrike advice

I have had a total of 4 .10 size overpowered Shrikes. I have never had no problems with the elevator. If you are going to overpower it, move the firewall back a 1/4". It helps with the CG. I have learned when landing to have high rates on the elevator set up. You need as much elevator as you can get. You will have no problem landing then. Also since you need weight in the back anyways, I use solid balsa between the fuse and the fins. My .32 powered one lands like a *****cat.
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Old 09-23-2003, 11:20 AM
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Default RE: Need shrike advice

I agree with ckoerner that it is easy to properly balance your Shrike when putting big engines in them. In fact, I rarely even need to use hi elevator rates on landing and mine slows down fine on low rates. I discovered this when I kept forgetting to switch over to hi-rate after my flights. Too nervous, I guess!

I did move my firewall back 1/4 inch (just enlarge the existing firewall slot) and I made a removable hatch in the rear of the fuse where the pushrod exits, instead of gluing it down permanently. It is just large enough for your battery and some foam padding and actually makes my 32SX powered Shrike ever-so-slightly TAIL-heavy, just the way I like it! Absolutely no need for any dead lead weight to balance it. And you don't need to relocate your servos toward the back, just install them as shown on the plans.

Actually, now that I think about it, I do have a full pipe on mine, which probably helps move the CG back a bit, compared to the stock muffler.

The only other mods I did were to strengthen the wing and the tail fins a bit.


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Old 09-23-2003, 11:26 AM
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Default RE: Need shrike advice

Darwin,
I think my Shrike w/.32and pipe is just a tad bit slower then my JETT FIRE .50 powered Diamond Dust. I can't tell the difference when I fly them back to back. I just like the looks of the Shrike better then the delta's. Next I want to do a .40 size Shrike with my JETT FIRE .50. Just have to figure how to get it to fit with the rear exhaust.
Later,
Craig
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Old 09-23-2003, 03:16 PM
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Default RE: Need shrike advice

Craig,

I got kinda tired of flying the Shrike so much last month, so I took out the 32SX and put it in my little 12th scale Reno-racer (American Jet F8F Bearcat), just to see what would happen.

This thing is a missle! Radar gun measured it at 150 mph! It's easily 5-10 mph faster than my Shrike. The only thing I can figure is that the Bearcat has only 230 sq. in. of wing area compared to ?? for the Shrike. Both planes weigh about the same (less than 3 lbs). So, drag must be greater in the Shrike even tho the Bearcat fuse has more frontal area.

Here's some pics of it:

http://www.sacramento-rc-flyers.org/...l03/index.html

Just click on pics # 2, 29, 30, 40 and 54. These were taken during a club 12th scale race event. I placed second with a 25fx in the plane that day (well, there were only 4 entrants, so no biggee). I did win a MVVS 21 motor and another 12th scale kit for the effort tho. Ha!

Anyway, I think I'll fly the bearcat for a while, just for a change. Its the speed addiction thing, you know...

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Old 09-23-2003, 03:25 PM
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Default RE: Need shrike advice

Darwin,
What prop are you running on the .32?
Thanks,
Craig
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Old 09-23-2003, 04:26 PM
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Default RE: Need shrike advice

8x8 apc on the Shrike
8x7 apc on the Bearcat
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