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Spad to the Bone Dominator Problem

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Spad to the Bone Dominator Problem

Old 11-16-2009, 07:34 PM
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norbon
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Default Spad to the Bone Dominator Problem

I built a Dominator exatly to the plans and balanced it right on the foward spar (with 5 degrees downthrust) and it flys like it is really nose heavy. On takeoff it wanted to nose over before ever leaving the ground and when it finally got airborne it was all I could do to keep it from noseing over. It is basically unflyable the way it is. Has anyone had this problem or have any suggestions?
Old 11-16-2009, 08:00 PM
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draftman1
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Default RE: Spad to the Bone Dominator Problem

hey Norbon, hmmm, it sounds like you need to adjust your ailerons up a little, if they are drooping a little, it will force the nose down. Im not sure if that plan explans it but some of the others do. when you look at the end of the wing, the alierons should be parallel to the fuse, your elevator might also need a slight adjustment also make sure your wing center line is parrallel to the fuse, incidence might be off a little
Old 11-16-2009, 08:17 PM
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Default RE: Spad to the Bone Dominator Problem

I have to agree with draftsman. One or more of those sounds like the culprit.
Old 11-17-2009, 02:04 PM
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kanillo
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Default RE: Spad to the Bone Dominator Problem

i have my dominator n° 4 and just like draftman, ailerons must be parallel to fuse and i move the wing like 10mm in front of CG
Old 11-17-2009, 02:13 PM
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Clean
 
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Default RE: Spad to the Bone Dominator Problem

As said before, If not a little re-flexed make sure the ailerons do not droop. Usually if the plane acts a little squirly in pitch dialing up the ailerons smooths it out unless you really are talking nose heavy. As for that how are you measuring CG. Do you use a sling, a stand or your fingertips? Used fingertips for years but sometimes it's easier to stick it in a sling, hang it level and see where the plumb bob is pointing. I've had a couple of airplanes that slinging it really caught some of balance situations. Anyways, if it's built to plans really it should only be the ailerons that are the problem, there's dang little else to go wrong.
Old 11-17-2009, 04:11 PM
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Villa
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Default RE: Spad to the Bone Dominator Problem

Is everyone who has commented comfortable with the five degrees of down thrust on the engine? I did not build the Dominator but I just read the instructions and that is what is recommended. Five degrees is a LOT. On my SPAD J3-Cub the wing is mounted MUCH higher than the engine thrust line and as I recall, the required engine down-thrust to counter the wing drag effects is closer to a few degrees. It would be nice to hear from others who have built the Dominator. My SPAD Twin Tail and SPAD Canard have zero engine thrust.
Old 11-18-2009, 08:59 AM
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norbon
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Default RE: Spad to the Bone Dominator Problem

Just a quick update to my problem. I have removed ALL downthrust, moved the landing gear foward 3/4", centered the ailerons to exactly neutral and rebalanced on a stand to level. I hope to try it again this weekend and will let you know if there is any improvement. Thanks for all the suggestions.
Old 11-18-2009, 10:40 AM
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Default RE: Spad to the Bone Dominator Problem

Hi kanillo
Buenos dias amigo. Since you are the only person who posted that you did build the Dominator, and are flying it, please give me more information. I am unable to understand the first sentence of your post. No entiendo. Are you saying that you built it with 4 degrees of down thrust? If not, what amount of down thrust did you use? Is your wing located per the instructions? Your message indicates your center of gravity (CG) is located 10mm to the back of the wing leading edge. That is only about 3/8" in our form of measurement and does not appear to be normal. I emphasize that I have not built or flown the Dominator, but I have designed and built about 6 other SPADS. I consider you the expert in this discussion since you built the Dominator and are flying it. I just want to know if you built it to the plans and if not, what exactly did you change and why. I read a little Spanish but not enough to understand you. You can send me an e-mail in Spanish if you like. I can get it translated with the Mexican friends I play racquetball with daily. Buena suert.
Old 11-18-2009, 11:56 AM
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Default RE: Spad to the Bone Dominator Problem

cool, that should help Norbon. you might also need to slightly raise the ailerons, if what you did, didnt quite help. it sounds like you have done all of the right things
Old 11-19-2009, 09:17 AM
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Default RE: Spad to the Bone Dominator Problem

The original SPADs all tended to pitch up at launch. This is more a factor of the semi flat wing on a flat fuse, trainer style setup. Angling down the engine will pull down a bit and counter this effect while being negligible at speed. Trainers, including the Big H Ray that I flew had 6 or 7 degrees of downthrust and right thrust to make up for the forces of the prop. Now generally I just chop the nose off square and go flying throwing the airplane a little under the horizon on launch and taking advantage of the raising tendancy. Chop the throttle at speed with no input and you'll see it doesn't pitch up as if the motor offset is being counteracted by elevator. Let it slow down and add throttle to it and watch it pitch up though. Oh the times I've had watching a newbie toss his Dagger nose up only to watch it climb, flop over and crash behind the pilot.

Jack up the trailing edge of the wing or use a symmetrical wing and these problems go away OR add downthrust.

YMMV but if you have a chance, go look at a full size Piper or Cessna and see the offset in their engines.
Old 11-19-2009, 05:44 PM
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BChris
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Default RE: Spad to the Bone Dominator Problem

Draftsman,

I was there for the flight and it was really horrible. For the first flight he had full up trim and full up elevator just to keep it in the air. Even then it would barely come up. We added a slight bit of flap for the second flight and it did come up, but the plane kept porpoising (sp). We double checked the balance and it was right on the money. I don't understand why you are recommending that we slightly raise the ailerons. It seems like that will push the noise down even farther making the problem worse.

Brad
Old 11-19-2009, 07:44 PM
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Villa
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Default RE: Spad to the Bone Dominator Problem

Hi Clean
I don't see full scale planes often. Are the engines offset? I have always assumed that there was no offset due to the increase fuel consumption that would result, but I did wondered if there was more to it.
Old 11-19-2009, 09:03 PM
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Default RE: Spad to the Bone Dominator Problem

hey Brad. Im not doughting you guys at all but it really sounds like the CG is off, try making it a little nose heavy. I have found out that when it porposes, its usually heavy on the tail. its short and close coupled so it will be a little pitch sensitve. I fly alot of wings and when a wing starts acting like that, I need to add a little weight to the front. also with a big elevator and surfaces you will get a plane that will be squirly, put some expo in it, make them not so sensative. on the aileron part, bring them up a little, when the are up, think of it as an elevator, it will act the same, so the nose will lift up.
I have built almost every spad on STTB and designed a bunch of my own. Probably the one that I didnt like was the demon, a low wing version of the dominator. it was really squrily, after a little tweeking and expo, it flew much better. I base the two planes dessign on most of it. its short fusaloge and the 6" wing tips that are flat. basicly you loose about 9" of real lift and stability.
personaly I would build the spadstick, you will enjoy that one

this was taken from the dominator build instructions
NOTE: When rigging your ailerons, ensure that the bottom of the ailerons are parallel to the top of the
fuselage! Do not allow then to droop (like flaps)! If your ailerons droop, they will drastically affect pitch
trim!

there was another place that told you how to set up the airlons but the link is missing, I will keep looking for it
Old 11-20-2009, 11:57 AM
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Default RE: Spad to the Bone Dominator Problem

Yes there is down and side thrust in full size aircraft, I can't find scale 3 views worth a poop but there is. The downthrust and side thrust become negligable aerodynamically at speed.
Old 11-21-2009, 09:54 PM
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Default RE: Spad to the Bone Dominator Problem


ORIGINAL: Villa

Hi kanillo
Buenos dias amigo. Since you are the only person who posted that you did build the Dominator, and are flying it, please give me more information. I am unable to understand the first sentence of your post. No entiendo. Are you saying that you built it with 4 degrees of down thrust? If not, what amount of down thrust did you use? Is your wing located per the instructions? Your message indicates your center of gravity (CG) is located 10mm to the back of the wing leading edge. That is only about 3/8'' in our form of measurement and does not appear to be normal. I emphasize that I have not built or flown the Dominator, but I have designed and built about 6 other SPADS. I consider you the expert in this discussion since you built the Dominator and are flying it. I just want to know if you built it to the plans and if not, what exactly did you change and why. I read a little Spanish but not enough to understand you. You can send me an e-mail in Spanish if you like. I can get it translated with the Mexican friends I play racquetball with daily. Buena suert.
Well, n°4 is the number of dominator builded

My down thrust is 0 (cero), i read that from a forum many time ago and works well for my

About my CG, was done like plans, but move my wing 10mm forward in order to avoid nose heavy
Old 11-24-2009, 10:08 PM
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norbon
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Default RE: Spad to the Bone Dominator Problem

I took out the downthrust, moved the landing foward 1" and retrimed the ailerons and it flew better but still real squirley. I decided to build a new fuse that is 7" longer and use the same wing and tailfeathers. CG and wing placement is moved to be the same ratio as the orgional. Will see what this does.
Old 11-24-2009, 10:53 PM
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Default RE: Spad to the Bone Dominator Problem

Thanks, Clean, for the full scale input.
Hi norbon
Have you checked the wing incidence? Your "squirley" description points in that direction. Mr.Clean pointed to that above when he suggested shimming up the wing trailing edge. If you don't have an incidence meter try this: view the wing end and draw an imaginary line from the leading edge (LE) to the center of the trailing edge (TE) thickness. This imaginary line must be parallel to the fuselage. About a 7/16" shim under the TE is not uncommon.
Old 11-25-2009, 08:27 AM
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Default RE: Spad to the Bone Dominator Problem


ORIGINAL:
. About a 7/16'' shim under the TE is not uncommon.

thats pretty much the norm
Old 12-01-2009, 08:11 PM
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norbon
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Default RE: Spad to the Bone Dominator Problem

The latest on the ill fated Dominator. I built a new fuse and made it 7" longer hoping that this would help stabilize it. It flew pretty good for about 4 minutes and then it started getting real squirrely again. Before we could get it down it went into a wide spiral (not a spin) and was out of control. It went down in an area out of our normal flying area, which we found to be a great swamp. We searched in knee deep water for several hours but never saw any sign of it. My guess is that it's underwater. We may find it someday as part of a beaverdam. We will never know exactely what its problems were but it was interesting for a while. RIP.
Old 12-01-2009, 10:30 PM
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Default RE: Spad to the Bone Dominator Problem

Hi norbon
I wish I could have helped you. Do you have good flying experience and have similar experienced people helping you? I have seen hundreds of models go out of control in the hands of inexperienced pilots who thought they had the experience. Sometimes slowing the engine down is the thing to do when things seem to be out of control. A lot of good advice was offered. I had a great time today flying my Twin Tail SPAD.
Old 12-01-2009, 10:45 PM
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norbon
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Default RE: Spad to the Bone Dominator Problem

I have about 3 years of flying , but when the SPAD went down one of our club instructors was at the controls. No lack of experience.
Old 12-01-2009, 11:41 PM
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Default RE: Spad to the Bone Dominator Problem

man, thats a bummer! I hate when that happens. I hope it doesnt leave a bad taste about spads. I hope you will find it also. you said that it was out beyond your normal field, by chance what reciver did you have? a park flyer model maybe? I have hd a couple of full range recievers not go full range. that would be my guess or a bad battery even. the plane wouldnt go in a wide spiral if it was controlable, no mater what. you would have had some control surfaces moving lke the elevator or rudder. the plane would have reacted. sorry about the loss!
Old 12-02-2009, 07:59 AM
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Default RE: Spad to the Bone Dominator Problem

Well then, I'd say you had a radio problem.


HAD
Old 12-02-2009, 12:02 PM
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Default RE: Spad to the Bone Dominator Problem

Hi norbon
As you can see, many of us are trying to help. Assuming you have made the corrections we suggested, your problem seems to be one that R/C experience can correct. Something wrong with the radio is very possible, and it being a SPAD has nothing to do with that.

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