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DP Extra does ugly snaps

Old 03-14-2004, 11:24 PM
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ilikeplanes
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Default DP Extra does ugly snaps

I'm planning on using my new DP Extra for Sportsman this year. When doing the snap, it looks more like a fast barrel roll than a snap. This is very disappointing because my other airplanes (CGM Sukhoi, CGM Ultimate) snap beautifully. It's almost like the Dave Patrick doesn't stall during the snap. My buddy that flies a DP Edge says I need to switch on high throw rates to do a snap. I never have had to do that on any other airplane before. I also seem to have a lot of over-rotation compared to my other airplanes.

I'm not even sure how the snap is judged. If I have a pronounce positive pitch during a roll, is it good?

What to do?
Old 03-14-2004, 11:38 PM
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David Cutler
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Default RE: DP Extra does ugly snaps

The best snaps (either purposely or accidentally!) are when the wing stalls, and it sounds like your wing is flying you through the maneuver as opposed to the model tumbling through it.

Increasing the elevator throw should improve the snap (at least, that's the main cause of an unwanted snap!). You could also try slowing the plane down to nearer the stall speed before trying the snap.

Also, a CG set back helps, but might make the plane too sensitive for the rest of the flight.

Just my 2.6c !

-David C.
Old 03-15-2004, 12:14 PM
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JAS
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Default RE: DP Extra does ugly snaps

We just test flew a Hacker power DP Extra and it snapped just fine. One thing I've found over the years is sometimes I take out too much rudder on low rate and the plane barrel snaps like you say above. I use high rate aileron (will snap on low rate(not too low), just not as crisp) with low rate rudder and elevator. Low rate Elevator is about 10 degrees and low rate rudder is enough to climb a bit on KE.
Old 03-16-2004, 02:13 PM
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XpastywhiteboyX
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Default RE: DP Extra does ugly snaps

where is you cg set i have a dp edge and it snaps great but the cg need to be a little aft. but i got 40 degres on the elevator 40 on rudder and 50 on aleron.
Old 03-16-2004, 03:18 PM
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ilikeplanes
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Default RE: DP Extra does ugly snaps

I actually am having a problem deciding where I want my C.G. I am currently at 5-3/4 inch. It seems too far forward per the NSRCA precision trimming guide. The part that gets me confused is elevator sensitivity. This airplane seems to have an extremely powerful elevator. For my style of flying, my elevator deflection is very small (3/4 inch). If I move the C.G. back, I'll have to cut my elevator throw even more.

All in all, I'm very challenged to get this airplane to handle the way I like. It may be too 3D oriented for me. The huge surfaces seem to be getting me messed up.
Old 03-16-2004, 08:37 PM
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FlyHard
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Default RE: DP Extra does ugly snaps

Sounds like you will be happier if you keep the CG at the forward part of the recommended range. I personally find this a wonderful plane and far as I am concerned it's the best of the ARF's, so don't give up.
Old 03-16-2004, 08:43 PM
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Default RE: DP Extra does ugly snaps

3/4 inch sounds close for a DP Extra. Don't be afraid of decreasing it even more; it is a very powerful surface. With my DP Extra, the snaps would be ugly unless I used lots of aileron and very little elevator and rudder.
Old 03-16-2004, 09:01 PM
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Default RE: DP Extra does ugly snaps

Well... I too have found snaps to be a bit alusive... try this... Expo (Elev and ail)... with more throw in low rate on ails and elev. Initiate the snap with elevator, (box the stick if you must) and as soon as the snap starts, get OFF the elevator.... you are left holding aileron and rudder. Some people will get off the rudder at some point prior to desired termination point of snap, (say... with 1/4 snap remaining) to facilitate snap ending on track. Chip has suggested NO ELEVATOR for snaps.... I have not yet explored this, but I have found doing 2 snaps on a vertical upline with a plane that is High AOA tolerant to be tuff... if they snap good when you want them to, they seem to snap good when you don't want'em to.... at least that has been my experiance.
Old 03-16-2004, 11:39 PM
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ilikeplanes
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Default RE: DP Extra does ugly snaps

Ryan, we will probably cross paths soon and I hope you'll give me some coaching. My routine really stinks right now, but I'm practicing. What's your experience on how a snap is scored.

The frustrating part is that my crummy little Goldberg Sukhoi does beautiful clean snaps by just pushing the sticks to the corners. This airplane has no bad habits, overly sensitive elevator, scary stalls, or any of that. If a 10 year old design can do it without trying, why does a modern design have to be coaxed?

Is the DP Extra really that stall resistant? If it is, it seems like I should explore a more aft c.g.

This getting to know each other phase sure can be frustrating.
Old 03-17-2004, 09:39 AM
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Default RE: DP Extra does ugly snaps

The DP can tolerate a CG further aft than where you have it right now. I'd say try it about 1/2" behind where it is now and see how it helps. I just noticed you said the plane seems to over rotate a lot - what I like to do for sequence flying is reduce the rudder travel until the overrotation is minimized or stopped altogether. If you need more rudder for Hammerheads or other maneuvers you can flip the switch to high rate, though I've found it not to be necessary for the most part. My DP Extra was in interesting beast - it definitely flew differently than my other Extras. However, once I got it dialed in it flew precision very well. As far as scoring snaps in IMAC, I've seen some "interesting" looking snaps score very well, so I wouldn't be too worried about it. Looking forward to talking with you again at some competitions this year!
Old 03-17-2004, 02:51 PM
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ilikeplanes
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Default RE: DP Extra does ugly snaps

Thanks for the advise. I just read the judging criteria. It sounds like the want a pitch up of the nose followed by a yaw and subsequent auto rotation. It also says that judging is very difficult because of the maneuver speed and aircraft differences.

I'm going to try leading with elevator and rudder and play around with the timing. I'll keep working in my set-up too.

I might make the Medford Challenge on 5/1.
Old 03-17-2004, 08:52 PM
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lhatton
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Default RE: DP Extra does ugly snaps

Please pardon my lack of knowledge here,

I'm a full scale pilot with just a little aerobatic training in a super decathalon. I was under the impression that stalling the wing was a prerequisite for snap roll.

How do you do a snap roll with no elevator?

The ones I've done were with full aft elevator and rudder in the direction or roll with no aileron used at all as I recall.

I've only done level positive snaps and avalanches ( if you can call mine that, heading control is weak, like 30 degrees off)

I've noticed the models enter a little better with some aileron to kick them off and needed none once established.

Les
Old 03-17-2004, 09:37 PM
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Default RE: DP Extra does ugly snaps

You start by giving some elevator, but then unload the snap by backing off a ways. If you don't, the plane will bury itself and does not do a clean recovery.
Old 03-17-2004, 11:01 PM
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Default RE: DP Extra does ugly snaps

Les,

What everyone is describing is not a true snap by the definition of a snap (high speed stall with yaw). It is a maneuver that gets an upward break of the nose to please the judges and makes them believe the plane is stalled, and then spins the plane with aileron and rudder to make it wallow a bit.

In competition, it pleases the judges because is looks just like the real thing. It is easier to control and doesn't kill all your energy if you are on an up line. Believe it or not, the full scale unlimited guys came up with it first!

CJ
Old 03-18-2004, 09:40 PM
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lhatton
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Default RE: DP Extra does ugly snaps

Thanks for the explanation.

I guess I'm gonna have to pay more attention to the commercials on discovery wings.

Les
Old 03-28-2004, 06:19 PM
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Default RE: DP Extra does ugly snaps

I have been flying DP Extra for almost 2 years. It is my best gasser, better than H9 33% extra. The snaps are great, heres my procedure:

1. Throttle back to 1/5 -- 1/2 if vertical -- 1 second before start
2. Small input on elevator
3. Lots of aileron and rudder, keeping some elevator
4. Neutralize elevator, reduce aileron and feed some power
5. Full power, no aileron, counter rudder (to end the snap) and elevator to trim the plane.

Just my 2c.
Old 03-28-2004, 08:50 PM
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Default RE: DP Extra does ugly snaps

............I have trouble walking and chewing gum.............

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