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Do You Fly Precision Aerobatics with a Biplane - I Need some help?

Old 05-16-2003, 04:17 PM
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splais
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Default Do You Fly Precision Aerobatics with a Biplane - I Need some help?

I am trying to move from bang it around flying to more precision. Along with this I am trying to improve my Ultimates trim and having some problems along the way. I'm not sure how much of this is biplane related or trim/CG related.

My CG is durrently at the back of the recommended range. I have an OS 1.08 in mine with 3oz of lead in the tail already.

Here are some of the things she does.

(1) Between slow flight (like landing pattern) and normal flight I need about 6 clicks of trim change to fly in balanced flight.

(2) In inverted flight I njeed quite a bit of forward stick to maintain level flight. Enough that it makes it hard to work things other than just flying straight and level.

(3) If i pull to inverted from straight and level I need to apply maybe 5 degrees of right rudder to maintain my line.

As additional info I feel like this plane could still use a CG further back. I actually land this plane on high rate elevator and have no trouble with pitch control at all.

Any comments are appreciated. -Steve
Old 05-16-2003, 05:08 PM
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3D_CAP232
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Default Do You Fly Precision Aerobatics with a Biplane - I Need some help?

Hi,
It sounds to me like that you have some thrust line issues i.e. downthrust or upthrust (depends on which way you adjust the trim for different flight speeds).
My trick to get the CG right is to do a vertical dive hands off, if it pulls to the canopy then its nose heavy, if it tucks to the belly its tail heavy...it should go straight down....it works for me!
This may help a little, i'd be intrested to see others views first though.
Cheers
Rich
Old 05-16-2003, 05:53 PM
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ilikeplanes
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Default Do You Fly Precision Aerobatics with a Biplane - I Need some help?

Splais, you are describing my Ultimate except the right rudder. I added a little down thrust to no avail. I'm starting to think the C.G. recommendation is way too conservative. I'm going to move mine back even farther.

I have about 2 to 2-1/2 right thrust. You should have about the same.

You're flying a Goldberg right?
Old 05-16-2003, 06:57 PM
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splais
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Default Do You Fly Precision Aerobatics with a Biplane - I Need some help?

Yes, it's a Goldberg Ultimate. And I have already discovered that as soon as the word "Precision" enters yours vocabulary things get a lot more complicated.

I have to make sure my getting off line when pulling up is not my clumsy fingers and I just realized I probably have to check my basic rudder tracking trim also.

When you talk about 2.5 degrees of right thrust, does that mean in addition to what Goldberg built in or all together.

I'm just now starting to read and understand Pattern Trimming Guides. But man they did not tell you how much work it was. Especially when you got 1-3 other planes in the pattern.

I will try that vertical dive test next time out. I'm glad to hear your comment because I too have always felt that for whatever reason, their CG recommendation is real far forward. This is not a difficult bird to fly and has zero bad tendencies that I can find. I start to get paranoid when I exceed the rearward recommendation, but all my tests say the CG is still to far back. I'm going to put the elevator servos in the rear and take that 3oz out any day know.

PS Ilikeplanes. Do you also have that slow speed-high speed trim change? A couple of,clicks is normal, but I think the bipe change is substantial.
Old 05-16-2003, 09:21 PM
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2fast4u
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Default Do You Fly Precision Aerobatics with a Biplane - I Need some help?

Try going to the "Pattern" section. Ask for the web page where they teach you how to trim a plane for "zero". That's when it will fly true in any attitude or at any speed. I printed it about 8 months ago, but forgot where it was on the web. It really covers all the bases. Good luck.
Old 05-17-2003, 03:03 PM
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ilikeplanes
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Default Do You Fly Precision Aerobatics with a Biplane - I Need some help?

Yes, I have the fast/slow problem and the upright/inverted problem. If you read the info at www.nsrca.org you will see that means nose heavy. When I fly the IMAC Basic sequence I find that I alway have some pressure on the elevator stick. Both up and down depending on where I am in the sequence. Yet another experience I had was on its first flight. The elevator was very non-sensitive (C.G. right on nominal). I have since increased the elevator to 1-1/4 and moved the C.G. back 1/2. I still use a lot of stick deflection on landing.

My right thrust is total.

Good luck and report anything you learn.
Old 05-17-2003, 04:48 PM
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Default Do You Fly Precision Aerobatics with a Biplane - I Need some help?

Remember you are flying a biplane, and the upper wing causes drag in all flying conditions, causing the nose too pull toward the top wing. You could make trim changes, but they will cause other problems.

You say your learning persision aerobatics, so get skilled at compensation for the extra drag and it will only make you a better all around pilot.
Old 05-18-2003, 01:55 PM
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Default Trimming your plane.

Myself and two other guys have the same Sig Cap 231 Breitling. We all fly together occasionally. And we compare plane setup and engine performance.

I am running a big ST engine in my plane, and the other two guys run a Saito 180.

We started trimming the planes according to the sheet that we got from the guys at Aeroworks. I had to add a boatload of right thrust to mine. And even some down thrust. Other guys had to add lot of down thrust and one guy had to also add a lot of right thrust.

Remember, the balance point that most manufacturers provide is only a safe point for starting out. It isn't written in stone that you must not go beyond those specs provided by the manufac. You'd be amazed at how far back I have some planes balanced. According to the plans and specs from the manufac. ; the plane should not fly, but they fly GREAT!!!

Try these tests. This is straight from the guys at Aeroworks.

For balance:

Full throttle flat and level. Pull to a 45 degree upline and roll inverted. Plane should continue up at a 45 degree incline. If it starts to drop the nose, then you are still nose heavy. If the nose goes up and the tail drops, then your tail heavy.

When adjusting the engine thrust, there are a few different methods. I usually try both and come too a happy medium.

For engine thrust:

Come in about half throttle- flat and level
pull straight vertical and wait for it to ALMOST stop
Slam the throttle full open and then close it quickly
Do it again
Slam it full throttle and then close it quickly

If your plane torques too the left more than you'd like, then add right thrust. If it's gonna torque left; then it will happen when you slam it full throttle when vertical.

If it doesn't torque left, then your probably fine.

Checking for proper up or down thrust is a bit more fun.

Come in flat and level- about 1/2 throttle
pull straight vertical
go Full throttle when perfectly vertical
LET GO OF THE ELEVATOR!!!!!!!!

Watch it and see if the nose comes back onto the top or if it goes towards the belly of the plane.

If your nose comes towards the top of the plane and you need to add down elevator to keep it vertical, then you need more DOWN thrust.

If the nose falls towards the belly and you need UP elevator to keep it vertical, then you need more up thrust.

The other way; I usually do the next method after the vertical test

Take it up HIGH.

Start out HIGH-200' or 300'- whatever you consider high
full throttle and flat and level
shut the throttle quickly and let it glide
DO NOT TOUCH THE ELEVATOR
watch it and look to see if it falls quickly

Your plane should glide reasonably well. If it is nose heavy, then it will come down fast and accelerate at an idle.

Keep in mind that aerobatic planes don't really glide very far, but most; if properly built and have reasonable wing loading, will glide for awhile. Any plane that drops like a rock after shutting the throttle is most likely, too nose heavy, has improper engine thrust or has DRASTICALLY high wing loading.

Check your incidence. Incidence meters are great. I use them on every plane I build. But there's no substitute for checking the plane in flight after setting it according to plans.

To check wing incidence:

Take it up REALLY REALLY HIGH- at least 300'
flat and level
1/2 throttle
close the throttle down to a nice idle
put the plane into a VERTICAL dive at idle
TOTALLY VERTICAL
LET GO OF THE ELEVATOR
watch it
pull out and throttle up before you get too close for comfort

What your watching for is to see what the plane does in a totally vertical position at an idle. You must do this Vertical, with the nose pointed DOWN at the ground. Thats why I say- start out HIGH.

If, when vertical, the plane comes down and pulls out to level flight. Then your wing incidence may be positive too much. On a plane that calls for ZERO incidence on all surfaces-(wing, stab and engine), it should come straight down.

Some might just come up towards the top and creep towards level. That might be fine. Depends on the plane.

If, when vertical, your plane tucks towards the belly and starts too pull out and go inverted, then your maybe a little on the negative side of the incidence.

Now for my disclaimer: I'm no genius. I read all this stuff in books and heard it from other more experienced pilots than myself. I do each and every one of these tests on all my planes now. Yes, I spend almost a gallon of fuel doing all these tests again and again. Each time; landing and adjusting. Then going through the test again. Sometimes I spend MORE than a galloon of fuel to get a plane right where I like it, but in the end, its money and time well spent.

I only try and adjust one thing at a time. One day I will take a new plane out and only work on engine thrust. Next time I take that plane out to the field, I will only work on balance or wing incidence. The point is; only adjust one thing at a time. And above all BE PATIENT!! (thats the hardest one for me)

Sometimes, you might think you have the engine down thrust right where it should be, then you go and start checking the incidence, and you wind up going back and changing the thrust again to make up for an adjustment that you made to the wing.

Believe me, I've spent a few hours chasing my tail when doing this stuff. But, a little tweak here and a little thrust there; and before too long, your plane is flying like you never thought it could.

Sorry I got so long on this one. I hope this helps. It takes a lot of time and fuel to get a plane just right , but in the end; it's time and money well spent.
Old 05-18-2003, 02:34 PM
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splais
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Default Do You Fly Precision Aerobatics with a Biplane - I Need some help?

No, thanks for the post. think I am going to concentrate on the CG first and finish my servo relocation and then go from there.

I do have another question for someone. I know what incidence is. But no matter how much I read and search I can't find out just what it is that is being measured. I.e., just what is it that an incidence metter uses as the baseline it measures the wing angle against. Did I say that right? You know what I mean. Steve
Old 05-20-2003, 03:29 PM
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Default Do You Fly Precision Aerobatics with a Biplane - I Need some help?

I calculated the balance as a percentage of mean average chord (MAC) and was quite surprised what I found. Per the plans, the forward point is 8% MAC and the aft point is 19% MAC. I calculated this accounting for wing stagger and sweep. My MAC is the true aircraft MAC.

I also calculated balance as if there were no sweep (straight wings). This turned out to be 30% MAC to 41% MAC.

So, I'm going to move my C.G. to about 30-33% MAC (true MAC including stagger and sweep). This is about 1 to 1-1/4 inch aft of the aft range on the plans. On an 8.75 lb airplane like mine, this amounts to 4.5 oz tail weight! I think I'm going to move my battery to the tail.

Splais, you should do the same calculation to verify my work. I'm very curious how it turns out.
Old 05-20-2003, 03:36 PM
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RCJones
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Default Do You Fly Precision Aerobatics with a Biplane - I Need some help?

ilikeplanes,
is this all for the Goldberg Ultimate Bipe?
Old 05-20-2003, 03:58 PM
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splais
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Default Do You Fly Precision Aerobatics with a Biplane - I Need some help?

Yes, unfortunitely the Ultimate that started this thread is a pile of wood scraps now. Can't wait until I can get another, hopefully soon.
Old 05-20-2003, 04:13 PM
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RCJones
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Default Do You Fly Precision Aerobatics with a Biplane - I Need some help?

I'm waiting for mine to be replaced too. Apparently the first shipment came and went and I didn't get one. Hopefully soon
Old 05-20-2003, 10:21 PM
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ilikeplanes
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Default Do You Fly Precision Aerobatics with a Biplane - I Need some help?

Yep, Goldberg Ultimate, 54 inch wing.

Sorry Splais.
Old 05-22-2003, 10:23 PM
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go vertical
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Default Do You Fly Precision Aerobatics with a Biplane - I Need some help?

if you want to fly something diferent in a biplane and you can build from a kit try a weeks solution x from miles reed design's they come in 4 differnt scales from 1/4 to 42% they are very smoth flying i'm flying a 90" 31# with a brison 104 twin it has great preformance
Old 05-29-2003, 03:08 AM
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Fred
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Default Bipe

Do you have a web sight for the solution ?
Thanks
Old 05-29-2003, 06:30 AM
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go vertical
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Default Do You Fly Precision Aerobatics with a Biplane - I Need some help?

i don't think it is a web persay but i do have an e mail adress for miles reed design's [email protected]
Old 05-29-2003, 12:28 PM
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splais
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Default New DP 1.20 Ultimate Just Arrived....

....It is, without a doubt, the finest ARF I have ever seen. I have had to re-evaluate what I consider a "quality" ARF. This thing surpasses anything I have seen from Horizon, PacAero, Kangke and several others. The companies mentioned are great companies; but DP is in a league of their own. To be honest, I don't know how they put out a plane of this high quality at the price they charge. Extraordinary!
Old 05-29-2003, 05:45 PM
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ilikeplanes
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Default Do You Fly Precision Aerobatics with a Biplane - I Need some help?

Have you decided on an engine? Moki 1.35, Webra 1.45, OS 1.60, Saito 1.80, oh-my.

Do me a big favor and calculate the CG as a percentage of MAC. I would really like to know if it's different than the Goldberg.

Have fun dude.
Old 05-29-2003, 10:05 PM
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splais
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Default Do You Fly Precision Aerobatics with a Biplane - I Need some help?

Well, to tell you the truth I already have it for sale. But not sure if I will sell it or keep it. The day after I ordered it I saw and bought a beautiful Ultimate already done. I'm waiting for it to arrive this weekend. I was going to put a YS1.20 in it because I had it and DP said it would fly great with the 1.20. The plane I purchased has a pumped Saito 1.80 in it, so we will see.
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Old 05-30-2003, 01:03 AM
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RCJones
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Default Do You Fly Precision Aerobatics with a Biplane - I Need some help?

Is that the DP 120 in the Bulldog scheme? The one I've been dreaming about and talking in my sleep about? Thats it! I can't take it anymore, I've got to have one. Could you take a pic from the side so I could see the lower half and maybe the bottom. I've got cash for pics! Why did you let me see that?
Old 05-30-2003, 02:14 AM
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splais
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Default Do You Fly Precision Aerobatics with a Biplane - I Need some help?

It's an exact copy of Jim Leroy's real Bulldog Pitts, but it is the DP1.20. I only have one other picture simular to the one shown. But I will have some more soon. If you click on the below link you can see pics of the real plane that will just make you go even more crazy!

http://www.bulldogairshows.com/v2/abouttheaircraft.html
Old 05-30-2003, 03:12 PM
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Default Do You Fly Precision Aerobatics with a Biplane - I Need some help?

Originally posted by RCJones
Could you take a pic from the side so I could see the lower half and maybe the bottom.
Also on the Bulldog Airshows website is a link to download the artwork to use on an RC model. I guess this is exactly what you want:

http://www.bulldogairshows.com/v2/rcmodel.html
Old 05-30-2003, 03:15 PM
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Default Do You Fly Precision Aerobatics with a Biplane - I Need some help?

I think this is what you want. Very nice isn't it?
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Old 05-30-2003, 03:27 PM
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RCJones
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Default Do You Fly Precision Aerobatics with a Biplane - I Need some help?

I have a sign shop and I can't believe he put his files for the artwork on the website...I will definitley do his plane now! Bulldog decals here we come.

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