stnick

My Feedback: (2)

I picked up a DD recently w/o engine. I have a new Rossi 45 with pipe, but I'm using a Thunder Tiger Pro 46 for openers. Servos are Futaba S9304, not sure what's on the throttle.
What is the CG and do I measure from the trailing edge? What throws and expo's? The battery cycled fine and is a 600ma that looks like it came with a Futaba flight pack, it is in front of the servos. The rx is a Futaba 127 and is behind the servos.
The pics show the servos and the battery. I wrote (600) on the battery.
I use the 9C and prefer dual rates with expo on practically everything I own.Also, I've read about guys hand launching themselves, what is the technique for this?
Thanks guys,
Nick Nichols

KC36330

I've got mine balanced on the 'fattest' part of the wing, where it humps up. i personally don't use dual rate or expo but my flying buddy doesn't have as steady a fingers as I've got so i have the duel rates set to 100% deflection but he has it on 60% expo.

for hand launch i hold it between the fins in my left hand, holding the TX in my right with my fingers pinching the ele/ail stick (i don't fly dumb thumb) with the right wing tip about 6" lower then the left i shove it WOT with my mouth and as soon as it stages on the pipe i let it loose, no toss required. the wings torque level as soon as it leaves my hand.

i don't think you'll have your hands overly full with the engine you mention, i use a Jett FIRE 60LX on mine and 160 mph is all it'll do, the people claiming 200+ are only fooling themselves. don't sweat the deflections much, just give yourself enough you know it'll fly (3/8" up/down), they fly great at very slow speeds and aren't nearly as agressive as they are at WOT so keep in mind you don't have to fly with an on/off throttle

hth
kc

EDIT: forgot to mention my elevons have been shortened to help with the hand hold during hand launch.

KC36330

Oh yeah, almost forgot, on the throttle servo when you get to flying with an engine/prop combo that turns up some massive RPM (i turn an 8.8x8.75 @ 21K static and about 26K unloaded in the air) you'll have to isolate the servo pushrod or vibration will destroy the servo insides. i use a piece of Ny-rod with a length of fuel tubing glued to it with a 1/4" spacing between the Ny-rod for vibration dampening.

kc

EDIT: pic now included

stnick

My Feedback: (2)

Thanks KC... When you say your CG is on the "hump" are you talking about the most forward spar? Roughly 14 inches from the wing TE ( not including the aieleron). If so, mine is nose heavy.
PS I hope you weren't damaged too much in the tragedy that hit Enterprise a week or so before the Perry Ga. meet.
Nick

cobratraxxas69

My Feedback: (31)

Although 3/8 of an inch up/down is recommended by the manual for all-around throws, I like more conservative throws on my dust and have set up dual rates:

For LOW RATES, I use:

4 mm up/4 mm down for ailerons

5 mm up/5 mm down for elevators

You can swich the ailerons to 5mm up/down to match the elevators.


For HIGH RATES:

I put the ailerons on full rate (125% throws), but only do that at higher altitude and for brief periods of time (when I want to roll like a drill bit ).

The rear CG limit is the rear fuel tank bulkhead (where the forward spar is). The forward CG limit is .75 to 1 inch forward of that position

KC36330

i only had some tree damage from the wind and a few parts off the house behind mine coming over the fence but no damage to my house at all, thanks.

on the balance with no fuel in it if i set it on a table it'll sit on that fat hump and balance like it's sitting on an egg so according to cobras 'by the plans' i may be a bit tail heavy but it files great even at idle it'll fly as smooth and slow as a high wing trainer. on the comment about the rolls that's about all i do, split S and roll it the length of the field about 10' off the deck, it's the only plane I've got that doesn't loose any altitude at all doing rolls, be they slow ones or so fast it's a blurry blob in the air, you just have to make that pause and make sure of the orientation before you push or pull elevator

kc

twigster

My Feedback: (8)

Here's what it says in the manual:

If you are using a computer radio with expo, we suggest that you run 100% expo on the ailerons and about 60% on the elevator.
(we are using full available throws. you may not want to use as much when you first test fly).
A good starting point would be 3/8" throw up and down for ailerons and 1/4" for the elevator both up and down
(if you use a heavier engine which brings the CG to the forward limits, go to 3/8" throw on the elevator).

...with that said, i have about 1 and 1/4 inch throws , but like i said before,, USE A TON OF EXPO~!!

The CG is at the forward spar. With anything over a .40, use a flat pack, and try to get it as far back as you can.

I launch mine by holding the left wing tip in my left hand,, with the right wing tip on the ground,, power up with my mouth,
let it go, and it will torque to horizontal,,,

Good luck with your dust, man! Let us know how it goes...

brewski

Can anyone tell me where I might find a DD kit?

cobratraxxas69

My Feedback: (31)

Right here:

http://morrishobbies.com/product_inf...417dc781efbbf4

twigster

My Feedback: (8)

there is one for sale in RCU right now!!!

http://www.rcuniverse.com/market/item.cfm?itemId=277244

i'd get if i didn't already have two, and a clipped wing awaiting motor!!!

brewski

I got it! Thanks for the heads up. Now I have the Wild Wiz and DD coming. I just have to beat the wife home everyday until they arrive!

scoeroo

My Feedback: (9)

I have a new in box kit if you are interested ??

brewski

I'm looking for ideas on how to deal with my DD at speeds above 140. It will pull up and right. It takes almost full left to keep it straight at WOT. It has no twist in the frame at all. Looks perfect. I was thinking about working with the motor thrust.

Mike Connor

My Feedback: (5)

As discussed in another thread, I had the exact same problem and it started after about 80 flights and much abuse. for around forty more flights I did many things like strip the covering off to check and reinforce everything to find and correct the problem. I also changed the radio and servos. I got a couple of good flight and then it started again. Very frustrating. It flies perfect until it hits that high speed point and then pulls hard up and right.

I think you will find that it is out of trim from that point forward at any speed during that flight. This points to the airframe. I finally crashed mine and was happy about it because of the frustration of the problem. I built a new airframe and things were wonderful again. I have heard of a couple of others that have the same problem. I really hope you find the problem and I would really like to know what it is. However, engine thrust is not the answer IMO.

brewski

Do you think that the air across the pipe could be acting like part of the right fin and add extra pull at higher speeds. I have a macs muffler available that I could put on it to see if there is a change but the down side is that I may not reach the speeds with the muffler that causes the problem.
The DD has never had anything close to a hard landing or abuse. I can lay it flat and check every gap and even thickness all over with calipers and it is good. Maybe the covering is tighter on one side than the other. I'll work on one part at a time to resolve.

Mike Connor

My Feedback: (5)

You would think that the abrupt and significant change in flight characteristics would mean a serious flaw that would be easy to find. I found that not to be the case and the frustration continued.

My only thoughts are from something I remember. It seems that after it hit that speed that caused problems I would have to re-trim the plane to fly at normal speeds. I noticed the elevons not straight after landing. I should have checked for airframe twist at that moment but can't remember for sure if I did. If yours is doing the same thing you might check it.

Something is really going out of wack when it happens because mine was like you bumped the elevons at least 50% up and right instantly when you hit a certain speed that was well above 100 mph. I wish I could help more.

alan e mey

I am new to form discussions, my obsvations of what happens at higher speeds is that as speed goes higher control surfaces take on
loads squared by the speed. Seams to me trim problems might be caused by the lack of torque from the servo controling that surface. I
would sugest you take a good look at the geometry of the linkage and the torque of the servo controling it.I have had simular problems
with elevator servos during high speed turns and loops. Digital servos and higher voltage helped my problem. Hope they will help yours.
Alan3dflyr

combatpigg

My Feedback: (3)

Fiberglass and allign the fins, then see if it still pulls up and to the right. Also, it is a good idea to slide carbon tubing over the 4-40 control rods. The worst place to try to actuate a full length flap is from one extreme end of the flap. The best control will be near the middle of the flaps' span.

brewski

Thanks. I had planned to change the servos to high torque's because I felt I that when it went right it took so much left to get it back and that the servos were stalling.

The carbon fiber tubing is also a good idea that I will do.

You are certainly right about the actuation point being the end of the flap being a weakness. I have other deltas with the servos out on the wing allowing the horn in the middle of the flap and this is way more efficient and effective.

freakingfast

My Feedback: (3)

If you have a DD kit in box, now may be a good time to use the ribs as a template to make more for your self. Who knows if/when new kits will come out or the quality. I will not use the original parts in a plane, only copies. The ribs are 3/32" thick and the engine mount and the little rectangles that fit into the spar ends are 1/8" thick aircraft ply. A Sears 10" band saw (table saw) model #119 214000 about $100 works fantastic to cut things up.

The jig is up...sorry I couldn't help myself. I made a fixture/jig to hold everything strait, square and spaced. This will keep the wing neutral, no wash in/out. At each hold point there are two blocks glued to the base plate (3/4" hard, strait particle board). One of these blocks is positioned to the inside line of an accurate layout drawn on the base plate, the opposite block is angled so a small wedge can be inserted between it and the rib. These wedges have surprising holding power; if you forget one and pull you will break something! Blocks are cut to hold up the spar at the proper height for the outer ribs. I used some adhesive backed Teflon tape under the 1/4 X 3/8 trailing edge so the CA won't stick the wing to the fixture or you can use some wax paper each time. The only parts that should be resting on the base plate are the rear 2/3rds of the main ribs and the trailing edge. Loading the fixture and gluing up a wing takes about 10 minutes. The fixture works with standard or clipped wing (clipped wing is loaded). This jig be made in a few hours, it's not worth it if you are making only a few deltas.

combatpigg

My Feedback: (3)

Nice photos, nice jig!
If all 3 corners are made strong, there shouldn't be any problems with the framework twisting. I use more like 3/16"-1/4" thick ribs, plus I like to use 1/32" ply rib doublers in the engine bay.
Control of these planes can be real smooth and precise if you use the inner servo arm hole and pivot the flaps about 1 1/8" up on a tall control horn.

freakingfast

My Feedback: (3)

A little Kevlar & carbon is a good thing

combatpigg

My Feedback: (3)

That looks good man. It sure is amazing how well that carbon takes to CA glue. I remember 15-20 years ago reading the C/L combat columns in the magazines and how they talked about the stuff like it was cutting edge rocket science. Too bad all this space age material has to be hazardous to work with. Imagine working at one of those plants.....might as well smoke and eat doughnuts 24/7 if I had to work at a C/F plant

IFlyRC5630

My Feedback: (50)

Can any of you LUCKY owners tell me where to get plans for a DD? I am flying an OUTLAW and having a ball with it. Most of the guys at our field swear it is going 150, but with 36" span I'm guessing 120 (maybe)......I'm running a Magnum 46 with pipe turn a 9 X9 prop on 30% heli fuel......it does "pick em up and lay em down"
thanks for any help you can give me.......

IFlyRC5630

brewski

I have plans that I'll try to scan and make a copy of tomorrow. I'll let you know if it goes well and PM you for mailing address.