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

Delta gurus I have a question

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Old 07-23-2007, 01:10 AM
  #1
AGR413
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Default Delta gurus I have a question

I like deltas but have always been leery of them, apply to much elevator and you get a high speed stall and or a snap and your headed for earth faster than a thirsty earthworm. So I'm playing with G3.5 tonight and thinking to myself I sure like this plane but the turns are scary and unpredictable. The question is I don't know if this is realistic but the plane on the sim has rudder, so I started playing with rudder and it turned the turns into an easy predictable movement. Does anyone do this, am I just a newcomer to an old trick?
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Old 07-23-2007, 01:56 AM
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Default RE: Delta gurus I have a question

I have a Green Models Delta 40 with a Magnum 52 installed.
It has dual rudders that I have set up and it does make turns easier and it more able to recover from a spin (Provided you have height).
The other upside is that I have them set up to work as speed brakes to slow it down a little for landing (Looks kind of cool to see it coming in that way).
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Old 07-23-2007, 02:40 AM
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Default RE: Delta gurus I have a question

.....I have the rudders on my Delta Vortex set up as air brakes too.

FBD.
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Old 07-23-2007, 07:15 AM
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Default RE: Delta gurus I have a question

I guess I'm abnormal. I've never been able to force my Diamond Dust to stall and spin? It doesn't have rudders, and I've never had any troubles with it turning or behaving badly.
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Old 07-23-2007, 07:54 AM
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Default RE: Delta gurus I have a question

I have never had any delta snap out on me from pulling too hard or any other control input that wasn't suppose to end in a stall. I've heard people talk about it but I have never experienced this or even seen it happen in fact I think deltas are pretty forgiving other than the fact with the speed they fly a mistake can put you in the dirt real fast but that is true of any airplane traveling at those speeds.
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Old 07-23-2007, 10:00 AM
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Default RE: Delta gurus I have a question


Quote:
ORIGINAL: AGR413

I like deltas but have always been leery of them, apply to much elevator and you get a high speed stall and or a snap and your headed for earth faster than a thirsty earthworm.
After two Diamond Dust and now my own design Delta it seems that Delta wings do not like to stall going fast or slow. This was discussed in the aerodynamics forums awhile back with guys that know more then me and there is a reason. We tried full elevator turns at different speeds on my new Delta and could not get it to stall. I did get high speed stalls on my Shrike but it is not a true Delta.
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Old 07-23-2007, 12:09 PM
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Default RE: Delta gurus I have a question

Wow this is turning out to be a great discussion where do I start.

I have experieced a similar problem with deltas, particularly in a steep turn (like when turning around to come back to the flight line, or on a down line pulling out) when more elevator causes a control surface stall or high speed stall and the plane just "pushes" out or tip stalls and becomes very unstable. In the sim I found out that a lot of rudder and a little bit of aileron/elevator input made high speed turns much more stable. On that particular aiplane there was no solution for downline pullouts except lots of altitude. BTW I believe the model in the sim is of a coro delta if that helps clarify anything.

So do I take from this discussion that some of you guys are using rudder to make standard turns?

Can we start some discussion on which deltas play nice and which ones don't based on your experience?
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Old 07-23-2007, 12:30 PM
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Default RE: Delta gurus I have a question

Ok. My experiece is that the Diamond Dust is very well behaved, and launches quite easily when built stock and is moderately quick even when powered by a docile .32SX. I'm building a BTE Vortex right now. It and the Diamond Dust are both very easy to build.
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Old 07-23-2007, 01:16 PM
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Default RE: Delta gurus I have a question

It won't snap.
You may be able to induce something that looks like a high speed stall, but stalls are docile on deltas. The worst that will happen is that you stop the plane in midair.
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Old 07-23-2007, 01:42 PM
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Mike Connor
 
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Default RE: Delta gurus I have a question

Most of the smaller Deltas, especially those built for speed, do not have rudders and don't need them. You can add rudders if you want a fun fly plane.
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Old 07-23-2007, 02:03 PM
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Default RE: Delta gurus I have a question

As stated, Deltas with rudders are fun to fly and crowd pleasers with snap rolls, flat spins and knive edges. Roll rates on most are crazy. Wild Wiz is a simple build and really fun with good speed. Diamond Dusts are great handling deltas build for speed. They can be as tame as you need them or you can increase the rates for a real rush. Mine, Wiz and Dust, have no bad tendencies at moderate speeds (<120 mph). The dust is pretty touchy and exaggerated at WOT. The best thing about deltas to me is that when you give them input they respond! I take any combination of Dominator, Harrier 3d, Sportster, SPAD and electrics to the field but the deltas rarely stay home.
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Old 07-23-2007, 07:53 PM
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Default RE: Delta gurus I have a question

My Dust never showed any bad tendancies. I would often come by on the deck at ~150 and pull a 90 degree turn straight up with no tip or other stall. It was always a crowd pleaser. I sold my Dust, worst day of my life.

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Old 07-23-2007, 09:07 PM
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Default RE: Delta gurus I have a question

It doesn't matter what type of plane it is, you can set any of them up to either fly great or fly like crap. Too much elevon travel will make a delta hard to handle. If the CG is correct and the wing loading is with in reason, these planes don't take very much skill to fly. For all around great performance, lighter is better. With dual rates it is fun to crank in a lot of flap movement for some high speed antics, but it is wise to have low rate throws dialed in for when you want to have fine control.
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Old 07-23-2007, 09:37 PM
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Default RE: Delta gurus I have a question

I haven't had any high speed tip stall problems with Dusts or Outlaws but the Whiplash I had tendencies and a wing called a Wedgie did as well.
Some of the things that emulate the symptoms of a high speed stall on a delta are; *one weak, slow or unmatched servos,* full throws are not the same,* one eleveron/linkage is weaker, too thin or more flexible,* over deflection a control surfaces,* or the lateral balance is off.

Food for thought; when you pull back hard, just how effective are those rudders back there on the top side now in turbulent air? Some small fins or strakes on the bottom could have some merit on some deltas that yaw on hard maneuvers.
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Old 07-23-2007, 10:09 PM
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Default RE: Delta gurus I have a question

The Whiplash planes sound like they are just too heavy, there are no aerodynamic fixes for being over weight. It would be interesting to see a direct comparison with identical engines between a 2.5 pound Diamond Dust and a 3.5 pound Whiplash.
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Old 07-24-2007, 01:35 AM
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Default RE: Delta gurus I have a question

Ok, you guys are right, the physics are probably not perfect anyway. I flew the Delta again tonight and for some dumb reason I guess I tried to fly on High rates all of last night. On low rate it was not that bad. But on high rates you can get in trouble in a hurry! Just for kicks I figured out how to capture the video from the flight, It has no sound probably super boring but here is the link:

[link=http://video.google.com/videoplay?docid=8322879346292444009]Flying a Delta in Realflight[/link]
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Old 07-24-2007, 07:37 PM
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Default RE: Delta gurus I have a question

Hey Duck. Here's how I got my Dust into an inverted flat spin.

I got tired of going fast so I started playing with slowing down to a high alpha. When the plane is nearly stopped, I shoved both sticks into the corners. You have to catch it just right, but it will snap around. A few times, I went around a turn or so and recovered. About the 3rd or 4th time, I held the stick down & left and full power and she went into an inverted flat spin. Would not come out. Idle to full power and any elevon control didn't work. I was fairly high so I had a long time to experiment while my buddy laughed while taunting, "Can't get it out. Can't get it out." The @#$%. It plopped down on the concrete and flattened the fins-that was all the damage.

Now, if I'm going to do something stupid with a delta, I always put a rudder on it. My twin Diamond Dust flat spins like a falling leaf, but comes out with a touch of opposite rudder. I did convert it to one huge rudder with a powerful, digital servo just in case.

As for flying and doing maneuvers, I've never seen any tip stalls or other bad behavior. When you get the nose up they lose speed like mad. If you want to land shorter, just pull the nose up and the plane will just about stop and sink. I've had a DD, the twin DD, a Mach RAcer and a couple of original deltas. They are fun planes.
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Old 07-24-2007, 09:20 PM
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Default RE: Delta gurus I have a question

Neat twin. Where can I find plans for that thing?
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Old 07-24-2007, 10:15 PM
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Default RE: Delta gurus I have a question

I WHip is heavy compared to the DD, so is the Phenom but it depends what you want to do with these things. If I want to flat-spin I will get a 3D plane, if I want great turning I get a Q-500, etc. I like the Whip/Phenom because it is tough, fast, paintable and cool looking.

I am soo sick of the "DD is soo much lighter" yeah it is and it is fragile like a flower compared to the composites.

I just like high speed passes, blindingly fast rolls and scary hand-launches.
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Old 07-25-2007, 10:52 AM
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Default RE: Delta gurus I have a question

My favorite trick (I have only done this with electric delta's): You gotta go way high, kill power and start full roll fast as you can. Once full roll speed is obtained (heading for the ground) hold that and pull full up elevator opposite rudder and add throttle. The more throttle you add the faster the spin. Be careful some deltas will not recover from this, most will.
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Old 07-25-2007, 07:05 PM
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Default RE: Delta gurus I have a question

Razor, the point of this thread is to explain why this guys' delta handles like crap. There is usually only 4 reasons why this can be so.....and they have all been covered.
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Old 08-17-2007, 08:45 PM
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Default RE: Delta gurus I have a question

where can i get my hands on a diamond dust or planes to build one porkchop the flying hog
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Old 10-03-2007, 12:06 PM
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Default RE: Delta gurus I have a question

Hello Gentlemen,

Lee here, from The Southernmost Flying Club, Key West, FL. Just wanted to say hello, and happy to have a forum like RCU to share ideas, stories, ETC..... Here's a photo of one of my birds, The Modeltech Mach Racer, I stripped down the covering, modifed the vertical stabs, and recovered with monokote flat black, and USAF decals. Fun little plane, attracts a lot of attention!
Have a great day,

Lee
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Old 10-03-2007, 03:14 PM
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Default RE: Delta gurus I have a question

Looks good Lee, and welcome to RCU.
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Old 10-03-2007, 09:36 PM
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Default RE: Delta gurus I have a question

Hello, Lee....we have been waiting for you....welcome to R/C Universe. [sm=thumbup.gif]

....did you eliminate the snare drum sound form your Mach Racer ?

Mine still sounds wierd, but it flies fine. I was impressed with how docile they really are.

FBD.
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