35% SD 260 needs hellashious up thrust!?!

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whaturi · 06-15-2007, 09:33 PM

Just got my first few trim flights on my 35% 260 with DA 100. I started with 0 degrees on all surfaces and the engine. I measured with a meter during the build. After flying it and adding washers, it is now just about right with over 3 degrees up thrust! What's the deal? I am trying to get this baby as straight as possible for competing, so it bothers me a bit. Is this just a function of the design\layout of the airframe??

3ddd · 06-15-2007, 09:36 PM

never have seen a plane need that much up thrust.did you check the firewall and the wing and stab incedences

Vic3D · 06-15-2007, 09:41 PM

Wouldn't be surprised if the stab incidence is not right. I would check that first.

dbcaster · 06-16-2007, 01:50 AM

I had to add 2 1/2 degrees to mine as well. My incidence was at 0 all the way around. I also wondered what would cause this but it sounds like we have the same issue.

aerolou · 06-16-2007, 09:17 AM

Could balance be an issue ? Nose heavy maybe.

freya1 · 06-16-2007, 01:21 PM

we had the same issue with the 30%, I made a plate to add about 2 or 3 deg upthrust, it now flies straight, does anyone know if the 42% 260 has the same issue, I am in the midlle of putting one toguether.

GremlinX · 06-16-2007, 01:49 PM

Sounds nose heavy to me... I have never heard of anybody needing this much. What is your method of checking the thrust value? How are you coming to the conclusion that the thrust is off?

flyin woodbutcher · 06-16-2007, 02:29 PM

Vincent , throw the plane in the pickem-up truck and come on down next weekend. There will be some of the top pilots on the east coast here for the event. I am sure someone can help figure it out.

DA 100 , good choice.

Later FWB

dbcaster · 06-16-2007, 02:35 PM

CG does not change this, it is not nose heavy. On an upline pulling to the gear will not be caused by CG. I had the same issue with trimming for level flight at higher throttle and the plane balloning when the throttle was cut. I don't believe that being nose heavy would cause this.

whaturi · 06-17-2007, 11:48 AM

Ok, I have mine flying well now. The plane was to TAILheavy. I added noseweight and also got the elevators centered better than they were. I beleive that the problem was a combo of those two things. I check my up thrust by flying horozontal with 3\4 power. Then I cut power and watch for pitch change. When I first took this baby out to test fly, it would pitch up insane amounts! I kept adding washers, moving the engine up to try to fix it, but I was only covering up my real problem; CG and elevator center adjustment. The CG is still on the tailheavy side.. the plane still hunts for trim a bit after cutting power, but seems to go either up or down; no preference. I think once I get her a little more noseweighted, this should stop.

FWB, I'll see you there.. but I want to get this thing going straight BEFORE flying in the contest!!

06-15-2007, 09:33 PM	#1
whaturi Bad-ass Super Contributer! Join Date: Aug 2006 Location: Harrisburg PA, Age: 30 Posts: 1,077	35% SD 260 needs hellashious up thrust!?! Just got my first few trim flights on my 35% 260 with DA 100. I started with 0 degrees on all surfaces and the engine. I measured with a meter during the build. After flying it and adding washers, it is now just about right with over 3 degrees up thrust! What's the deal? I am trying to get this baby as straight as possible for competing, so it bothers me a bit. Is this just a function of the design\layout of the airframe??

06-15-2007, 09:36 PM	#2
3ddd tissue ? cry baby jack wagon! Join Date: Jan 2006 Location: pyote,texas Age: 58 Posts: 2,651	Re: 35% SD 260 needs hellashious up thrust!?! never have seen a plane need that much up thrust.did you check the firewall and the wing and stab incedences __________________ Life's journey is not to arrive at the grave >safely and in a well preserved body,but rather to skid in > sideways,totally screwed up,worn out,shouting,"oh damn what a fine ride! AMA 98634 > HEY I GOT A DIVORCE----HELL YEA > Futaba, FROMECO:a good way to get a charge out of life,,3w all the way for a good day

06-15-2007, 09:41 PM	#3
Vic3D Mother Huckin' Join Date: Jan 2006 Location: Caguas, Puerto Rico Age: 25 Posts: 4,304 Awards Showcase Total Awards: 3	Re: 35% SD 260 needs hellashious up thrust!?! Wouldn't be surprised if the stab incidence is not right. I would check that first. __________________ Pilot RC Aztech Aero/Secraft/EG Aircraft B&E Graphics, Jersey Modeler, TailDragger RC

06-16-2007, 01:50 AM	#4
dbcaster Bad-ass Super Contributer! Join Date: Dec 2006 Location: Petaluma, CA Posts: 816	Re: 35% SD 260 needs hellashious up thrust!?! I had to add 2 1/2 degrees to mine as well. My incidence was at 0 all the way around. I also wondered what would cause this but it sounds like we have the same issue.

06-16-2007, 09:17 AM	#5
aerolou Uber Contributer Join Date: Jan 2006 Location: Wytheville VA Age: 52 Posts: 190	Re: 35% SD 260 needs hellashious up thrust!?! Could balance be an issue ? Nose heavy maybe.

06-16-2007, 01:21 PM	#6
freya1 Doo It! Doo It! Join Date: Jan 2006 Location: Modesto, Ca. USA Posts: 95	Re: 35% SD 260 needs hellashious up thrust!?! we had the same issue with the 30%, I made a plate to add about 2 or 3 deg upthrust, it now flies straight, does anyone know if the 42% 260 has the same issue, I am in the midlle of putting one toguether. __________________ "I don't drive fast, I fly low"

06-16-2007, 01:49 PM	#7
GremlinX Father of the Scale Furum Join Date: Jan 2006 Location: Chapel Hill, TN Age: 34 Posts: 4,577	Re: 35% SD 260 needs hellashious up thrust!?! Sounds nose heavy to me... I have never heard of anybody needing this much. What is your method of checking the thrust value? How are you coming to the conclusion that the thrust is off? __________________ "I'll have the roast duck with the mango salsa" Kit builders check out.... http://bobflies.com/ 2.4 GHz is for your home telephone... 14MZ and 72 MHz for huckin' baby!!

06-16-2007, 02:29 PM	#8
flyin woodbutcher Diving for DA's Join Date: Mar 2006 Location: Ashland Va Age: 49 Posts: 1,578	Re: 35% SD 260 needs hellashious up thrust!?! Vincent , throw the plane in the pickem-up truck and come on down next weekend. There will be some of the top pilots on the east coast here for the event. I am sure someone can help figure it out. DA 100 , good choice. Later FWB __________________ BIG JERRYS RC AIRPORT: Shut down, gone for good " you earned them zeros " DA 170 "better to wait than make a mistake" Mona Vie wana be "man up and support your CD "

06-16-2007, 02:35 PM	#9
dbcaster Bad-ass Super Contributer! Join Date: Dec 2006 Location: Petaluma, CA Posts: 816	Re: 35% SD 260 needs hellashious up thrust!?! CG does not change this, it is not nose heavy. On an upline pulling to the gear will not be caused by CG. I had the same issue with trimming for level flight at higher throttle and the plane balloning when the throttle was cut. I don't believe that being nose heavy would cause this.

06-17-2007, 11:48 AM	#10
whaturi Bad-ass Super Contributer! Join Date: Aug 2006 Location: Harrisburg PA, Age: 30 Posts: 1,077	Re: 35% SD 260 needs hellashious up thrust!?! Ok, I have mine flying well now. The plane was to TAILheavy. I added noseweight and also got the elevators centered better than they were. I beleive that the problem was a combo of those two things. I check my up thrust by flying horozontal with 3\4 power. Then I cut power and watch for pitch change. When I first took this baby out to test fly, it would pitch up insane amounts! I kept adding washers, moving the engine up to try to fix it, but I was only covering up my real problem; CG and elevator center adjustment. The CG is still on the tailheavy side.. the plane still hunts for trim a bit after cutting power, but seems to go either up or down; no preference. I think once I get her a little more noseweighted, this should stop. FWB, I'll see you there.. but I want to get this thing going straight BEFORE flying in the contest!!

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