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Old Jan 24, 2004, 08:34 PM
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Plano, TX
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The bottom....
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Old Jan 24, 2004, 10:04 PM
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Trophy Club Texas
Joined Jan 2004
154 Posts
Great covering job. Looks awesome. You will have lots of fun with it. I love mine.
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Old Jan 24, 2004, 10:25 PM
777
Bought at a price.
Winfield, Kansas, United States
Joined Jul 2002
1,570 Posts
Hey guys, help me out. I hear about the speeds that the Devastator has been achieving & I'm stunned. It seems as though claims of 100+mph are the norm. No flames here, really! I've talked to Justin. Cool dude! But please help me out. Why are they so fast? I have an E-Zipper currently with a 16/15/4 in it & it will soon have a 16/15/3. Despite that, I seriously doubt that I'll get into the 100's in level flight.

Are they really that different? Do I need to trade the E-Zipper in?

Thanks,
Brad
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Last edited by 777; Jan 24, 2004 at 10:28 PM.
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Old Jan 25, 2004, 02:34 PM
Just fly the darn wing!!!
ScYcS's Avatar
Germany, NRW, Herford
Joined Oct 2003
2,210 Posts
Brad,

i know what you're talking about. I think you should not get rid of the eZipper. It's a nice flying plane and you can achieve similar speeds with both wings, the Devastator maybe a little faster but i doubt you'd see a difference just by looking at it.

Despite the fact that i never achieved those speeds myself, i think the "secret" of achieving high speeds is very light built (Lipos), very high voltage (10-12 cell nicad or 3-4 cell Lipo), a nice brushless coupled with a low diameter prop with a high pitch (4.5x4.5 e.g.). The thrust is hurt a little with these small props but the end speed is higher.

All of these factors together should make a very fast wing. However, if you are in any rate a little bit like me, then i'm not even sure if this is what you desire. I rather have a fast wing that i can control nicely and that is predictable than a rocket that i have problems controlling.

Speed IS nice but too much speed imho is just stress.

Dennis
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Old Jan 25, 2004, 02:54 PM
777
Bought at a price.
Winfield, Kansas, United States
Joined Jul 2002
1,570 Posts
Thanks Dennis,
My plan is to make a screamer. I have considered 4/5AUPs for it. I'd even consider Li-Po's but I don't know much about them yet.

My Unicorn will get the 16/15/4 & should remain my "nice" flying plane. However I'd also like a plane that would bring me closer to diapers than I have been in a long time. Every now & again, that could be fun!

Thanks again,
Brad
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Old Jan 25, 2004, 05:38 PM
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Kamloops
Joined Dec 2001
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777
You then want what Brad Stated 10-12 cells 16/15/3 or equivilent. (020 4 turn as a example also a Hacker B20-18L) You want to build it light but strong and put in as many cells as possible with a 4.75x4.75 Graupner speed Cam prop or agian... something similiar.

I myse;f am going to be using a mega 15/3 4.75x4.75 Speed cam prop and Two 2100 3S1P TP Packs. Hopefully it will be a real screamer..If not I will try my 4/5FAUP 11 cell pack

THECHOSENONE
Let us in on your speedster. Iwould actaully like to see some rardar pics of some speeds. Now that would be COOL! I really really hope your cliams can be accomplished if so i will be the first on your list to guy one. Any Sneak peaks?

MAl
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Old Jan 25, 2004, 06:10 PM
777
Bought at a price.
Winfield, Kansas, United States
Joined Jul 2002
1,570 Posts
Thanks Kushal,
So I have the 16/15/3 but about the two 2100 3S1P TP Packs. Please school me. I am not very knowledgable about Li-po's. Where could I get such a pack. I'm interested in finding the weight and cost. Are they just a likely to make a super-fast plane as are multiple Nimh's?

Why such a small prop? Would the Cam Speed 5.2 x 5.2 be a good choice as well? I plugged in some information on the P-Calc area on the Diversity site & it seemed as though the 4.75 x 4.75 did not do as well. Then again, it's a program & not reality, so I'd like to hear your experiences.

Thanks again,
Brad
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Old Jan 25, 2004, 06:28 PM
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Plano, TX
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Final pics....
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Old Jan 25, 2004, 06:29 PM
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Profile with the 9 Kan 1800's sticking up.
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Old Jan 25, 2004, 06:30 PM
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Oooops... forgot the picture.
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Old Jan 25, 2004, 06:34 PM
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Closeup of the component install.
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Old Jan 25, 2004, 07:48 PM
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Lucas, Kansas
Joined Nov 2002
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TwinSpar,

Your Devastator looks very nice. You should be able to sink the battery deeper into the wing to avoid having the pack sticking out of the top.

__________________
For you guys that want to really make the Devastator approach its maximum speed potential, here are a few tips.

Start with a Mega 16/15/3 and an APC 6x5.5 thin electric prop.

Cut the prop down to 5x5.5 and balance the prop.

You will also need a 35A ESC to prevent the motor from cutting out, and set the ESC to the maximum timing advance setting.

You will also want to use cells capable of supporting 35A bursts. If using Nicad or NiMH cells than a minimum of 10 cells will be needed (11-12 cells if you can make them fit). If using TP 2100 cells than you will want a minimum of 3s2p packs, or even a 4s2p pack to push the motor.

This will yield a Devastator that is capable of 100+MPH in level flight on an otherwise stock airframe. To get in to the 140MPH range, You will want to bury the pushrods. This one item can make a noticeable difference in speed when over 100mph.

To date, we have achieved 141mph only once. A second Devastator was recently built using LiPo power (3s2p) and has been clocked (by an off-duty AZ Highway patrol officer) at 134MPH. On both occasions the Devastator was flown in an extended dive, estimated to be ~30 degrees, and then past the officer at 15-25 feet up and about the same distance away. He did hide behind an SUV while taking the readings along with the pilot. Both readings were taken on a freshly charged pack and on the first pass each time. Speeds did decrease on additional passes. The LiPo Devastator is being fine tuned and we will video the next set of speed runs with split screen showing the RADAR and the plane during the speed runs.

Launching with the 5x5.5 prop is a little hard, and requires a strong throw. The LiPo powered Devastator is considerably lighter, but still requires a strong toss with the throttle set around 1/2. MotoCalc and P-calc do not simulate real-world results and are only a reference point.

Building a Devastator using these specs does not guarantee identical speeds. Much tuning and excessive care must be taken to insure the cleanest airframe and the perfect CG location and minimum linkage slop. It is a process that many would not take the time to complete to gain an extra 10 or 20MPH.

If you are wondering what makes the Devastator different form other 36-inch wings, the primary difference is in the cord length, airfoil design and thickness.

The Devastator has a longer cord length than other 36-inch wings. The longer cord length produces less drag at high speeds than a short cord wing. In general, this allows greater speed from the same power system. However, the lower drag only becomes an advantage when at high speeds, and most other 36-inch wings will run neck and neck with the Devastator up to around 100mph. Secondly, the Devastator has a little more room in the airframe for different battery packs, allowing more power options to be explored.

The difference is obvious when the Devastator is placed next to another wing in the same class. The majority of the wings on the market are VERY high quality, and everyone should be proud to own them. The Devastator is yet another wing, but is different in many aspects to the other wings on the market. Soooooo many good choices. I wish everyone the very best no matter what brand wing they chose, and I hope I can always be of service.

Thank You,

Justin
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Old Jan 25, 2004, 08:11 PM
777
Bought at a price.
Winfield, Kansas, United States
Joined Jul 2002
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Wow! Very helpful post, Justin, thanks a bunch! Please tell me, how do you cut down a prop? Having that ability would sure open up some choices in prop selection.

Thanks again...that explains a bunch!
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Old Jan 25, 2004, 09:17 PM
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Clinton, Maryland
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Twinspar I PMd you.
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Old Jan 25, 2004, 09:17 PM
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Plano, TX
Joined Sep 2003
140 Posts
Quote:
Originally posted by birdofprey
TwinSpar,

Your Devastator looks very nice. You should be able to sink the battery deeper into the wing to avoid having the pack sticking out of the top.

Justin,

I had it sunk to the point of being completely buried and with enough room for the coroplast top. It didn't leave enough room for velcro on the battery. This is the first wing that I have ever built and I wasn't sure how much foam beneath the battery was enough. I chickened out and reinforced the base of the compartment with that wierd sign board material and made the choice to go with the battery exposed. I've learned quite a bit on my first venture into wing building. The D is probably not the best platform for a newbie builder (it is a kit for the experienced builder with all the possibilities that are left open to the builder) but I've learned a hell of a lot through the process.

I started this project with the goal of learning as much as possible on one project. I chickened out of going with sunken controls but may go back and retrofit when I recover it. I also jumped into brushless when I hadn't really expected to. I did jump into an ultracote finish when I had originally planned for tape. I also dove into the need for bigger/more batteries with the addition of a brushless motor. I did manage to loose one of the stock/original winglets and used the remaining one to cut a set from standard 4mm coroplast. I like the double layer coroplast that Justin provides much more than the standard 4mm stuff.

Things that I would do different after my learning experience:

  • Use light weight spackle to fill the spar slot after spar install.
  • Use less of the bi-directional strapping tape. It adds up on the scale.
  • Don't buy batteries until you have made your motor choice!
  • Know how much foam will support a battery.

All in all.... I'm pleased with the results of my maiden venture into wing building. I was really perplexed at how to deal with the ultracoat but came up with a technique that really worked well (I'll take pictures of the patterns and explain the process later). I learned that a dremel with a router platform works well but that you should work in shallow layers and not try to go for the whole depth all at once. I probably over-engineered on this wing (from a durability perspective) but that comes from my motocross/off-road motorcycle racing mentality....

I can't wait to maiden the D!
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