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

OS 91 VR DF SHRIKE

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Old 01-06-2009, 12:39 AM
  #1  
soinks
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Default OS 91 VR DF SHRIKE

Has anyone tried a OS VR DF 91 on lainer 40 shrike? I have both of these and wanting to try it but would like to here from anyone that has tried it or know anything about it. Do you think that it'll be a waste of time or what I'm flying the shrike now with a os 46 fx which is ok fast but would like to go faster. Any help or info would be appriciated
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Old 01-06-2009, 08:25 AM
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Default RE: OS 91 VR DF SHRIKE


ORIGINAL: soinks

Has anyone tried a OS VR DF 91 on lainer 40 shrike? I have both of these and wanting to try it but would like to here from anyone that has tried it or know anything about it. Do you think that it'll be a waste of time or what I'm flying the shrike now with a os 46 fx which is ok fast but would like to go faster. Any help or info would be appriciated
Those things on the right prop will haul a decent clean airframe right up there by that magic number beginning with a "2" [>:]. Just my personal opinion, but if you have an engine like the .91 it seems kind of a waste to bolt it to something like that - do you really think the structure can take it? I have my doubts, but whadda I know. I just have a vision of a nice engine augering in on a fuselage sans wings.. [X(]. But heck, someone's got to try it, don't they? Stand back!

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Old 01-06-2009, 10:18 AM
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Mike Connor
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Default RE: OS 91 VR DF SHRIKE

Consider it is going to be very nose heavy when building and beef it up some. If you can shorten the nose so it will balance without adding a lot of weight it might be fun. I really like my Shrike and it moves along well with the right power.
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Old 01-06-2009, 07:15 PM
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Default RE: OS 91 VR DF SHRIKE

A tuned pipe will help balance it.
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Old 01-14-2009, 09:26 AM
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Default RE: OS 91 VR DF SHRIKE

I also had a shrike, mike is right about moving the firewall back probably an inch would be good. I believe the airframes are stronger than you think. Go for it
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Old 01-14-2009, 10:14 AM
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Default RE: OS 91 VR DF SHRIKE

We have one here with the OS DF .61. Moves very well. I do not think the combo od Shrike and .91 will get to 200 though.
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Old 01-14-2009, 03:01 PM
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Default RE: OS 91 VR DF SHRIKE


ORIGINAL: evan-RCU

We have one here with the OS DF .61. Moves very well. I do not think the combo od Shrike and .91 will get to 200 though.
No, but that engine can do it in the right airframe I think.

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Old 01-14-2009, 08:45 PM
  #8  
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Default RE: OS 91 VR DF SHRIKE

it is one of the few (large) engines in the german speed circles. those guys know how to go 200 and then some.
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Old 01-14-2009, 08:48 PM
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LGM Graphix
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Default RE: OS 91 VR DF SHRIKE

ORIGINAL: soinks

Has anyone tried a OS VR DF 91 on lainer 40 shrike? I have both of these and wanting to try it but would like to here from anyone that has tried it or know anything about it. Do you think that it'll be a waste of time or what I'm flying the shrike now with a os 46 fx which is ok fast but would like to go faster. Any help or info would be appriciated
I'm assuming you are the same guy that emailed me asking about this, in case you're not though, I had a Shrike with an OS91VRDF, here's what I said in my email.

Hi there,
You will want to shorten the nose or you'll never get it to balance
without it weighing way to much. You will also want to replace your
wing
spars with carbon fiber ones and fiberglass it all into the center
section
for strength.
Use at least 80oz servo's on the ailerons and 80oz on the elevator.
You'll need to put in a second tank behind the first one and run them in
series or you'll have almost nothing for flight time, that engine burns
through 22oz of fuel in about 7 minutes at full throttle so you'll want
to
fit at least 11oz in the shrike.
Put some plywood or at least a hardwood runner on the bottom of the fuse
from front to back to strengthen it as well, it will land much faster.
In the end, I didn't like it much with the OS91VRDF, a hot 50 would be a
better choice in terms of overall flying. The shrike is a very draggy
airframe, it takes a lot of power to get it going fast.
If yours is already built you're probably going to have a very hard time
making the 91 work, the carb is on the back of the engine as well so
that
means the firewall needs to move quite a bit, I think I moved mine 2"
and
I also put a bigger spinner on the front and built the fuse to match
that,
I think it was a 2.5" spinner.
Hope that helps
Jeremy
Some other questions were asked regarding the setup:

> HI Jeremy
thanks for the info, do you think that you need to do all of the mod's I
do
expect to move the fire wall and a little other things but if you just
want
to go fast straight and level. I'm wondering why you didn't like the
shrike
with the 91VR DF
Reggie
And my last reply:

Hi Reggie,
You need to do all the mod's if you want the airplane to hold together.
The wing spar system on the Shrike is fine for a 40 to 50 size engine, but
when you put in the extra weight of the 91 with a pipe, and the extra
fuel, combined with speed, that increases the G loads even in straight and
level flight significantly. You could probably get away with just using
spruce spars, but you want extra fiberglass from the wing to fuse joint as
well as where the spars meet inside the fuse.
The main reason I didn't like the shrike with the 91 was simply that it
was very heavy, and due to the draggy airframe it really wasn't as fast as
I'd hoped considering the bigger engine. It was quick, but for the effort
and hassles I had to go through a Sig wonder with a JETT50 would have been
faster. Or a Diamond dust with almost any engine.
Jeremy
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Old 01-15-2009, 10:11 AM
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Default RE: OS 91 VR DF SHRIKE

I have s Shrike with a Tower Hobbies 75 on the nose and it doesn't even have lead in tail. I do have a flutter issue that I am working on. Key things to do, move firewall back and put battery in wedge just in front of elevator. That is about it, it flies well and lands decent.
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Old 01-22-2009, 03:01 AM
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Default RE: OS 91 VR DF SHRIKE

LGM , do you have a pic of the Shrike with the OS91VRDF ??? would be great to see it.

You said that it wasn't too fast but how much is not too fast ??? 170 , 180 , 190 , 200 MPH ??? I remember a guy saying his Shrike .10 with a .60 engine was able to reach 200 MPH , I think the Shrike 40 with the OS 90 is kind of equivalent .

Do you think a reduction on the airfoil will help to gain considerable speed ? let's say..... 5/8" at the highest point on the first rib and proportionally on the others ribs ???




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Old 01-22-2009, 10:53 AM
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Mike Connor
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Default RE: OS 91 VR DF SHRIKE


ORIGINAL: SpeedBoy

Do you think a reduction on the airfoil will help to gain considerable speed ? let's say..... 5/8" at the highest point on the first rib and proportionally on the others ribs ???
I thought about building a Shrike 40 and reducing the airfoil down to about 8%-10%. Mine was built stock and had a Jett 46/50 for power. I always considered it a fairly clean airframe with little hanging in the breeze. It would easily stay with my Q-500 planes, until it came time to turn. Mine had a bad accelerated stall tendency.
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Old 01-22-2009, 12:54 PM
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Default RE: OS 91 VR DF SHRIKE

Hey Mike , yes I remmeber have read your Shrike and if I'm not wrong she went 163 MPH with the jett .50 rigth !!.

But why you think she had a bad accelerated stall tendency ??? I mean wich was the cause .

I'm building mine ( .40 size ) and the reduction on the aifoil has been done , do you think it will be a problem on its behavior ???

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Old 01-22-2009, 07:00 PM
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Mike Connor
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Default RE: OS 91 VR DF SHRIKE


ORIGINAL: SpeedBoy

Hey Mike , yes I remmeber have read your Shrike and if I'm not wrong she went 163 MPH with the jett .50 rigth !!.

But why you think she had a bad accelerated stall tendency ??? I mean wich was the cause .

I'm building mine ( .40 size ) and the reduction on the aifoil has been done , do you think it will be a problem on its behavior ???

I wont make any speed claims on my Shrike but those that saw it fly said WOW, that is quick. Most thought it really looked good flying by, except the neighbors who said "that bat looking thing that made a lot of noise".

Aggressive turning like a pylon turn would likely cause an accelerated stall snap roll. I have heard a few other aggressive flying pilots say the same thing. We talked about it over in "aerodynamics" and despite the large vertical fin area, some thought the fins were blanketed from the air mass at high angle of attack turns. Some thought it was just a tip stall being aggravated by my sharp leading edge. If I build another I will round the outer portion of the leading edge of the wing. I will leave the inner portion of the wing leading edge sharp to act as a stall strip.

It is a great flying plane and a reduced wing thickness should not hurt that. Just get used to how it turns at altitude.
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Old 01-23-2009, 12:11 PM
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Default RE: OS 91 VR DF SHRIKE


ORIGINAL: Mike Connor


It is a great flying plane and a reduced wing thickness should not hurt that. Just get used to how it turns at altitude.
OK , I'll keep that on mind .

Thanks Mike.
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