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Byron Pitts CG

Old 05-11-2011, 09:33 PM
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Default Byron Pitts CG



I'm pretty sure there are some of you out there still flying the Byron Pitts S-1. My question is how far back can Ipush the CG on this airplane without getting into trouble?

I built this airplane back in the 1990's, flew it a few times then sold it. I recently bought it back and did some refurbishing. It flew it's first flight in 18 years today and although the CG seems to be about right (manual says 1/2-1 inch forward from the leading edge of the bottom wing) the plane acts nose heavy. It took a fair amount of up elevator trim and attempts at loops didn' t go so well. Overall, the elevator just seemed sluggish.

I don't know if it's underpowered (Supertigre 3000 with 18x6-10 prop) or maybe I'm just not used to the feel of this size and weightairplane.This is the only large scale plane I have owned/flown so my experience with the fine tuningthistype of plane is limited.

Thanks in advance for any insight and/or suggestions on the CG or the engine prop combination.</p>
Old 05-12-2011, 03:19 AM
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Default RE: Byron Pitts CG

fgibson ,
First - I don't have a Byron Pitts but I have had several Byron Christen Eagles over the years and they fly alot alike .
They are both very short coupled planes and are very sensitive to C.G positioning .
There are also more than a few factors that can make the perform poorly .
Engine thrust line - Is is set to spec ,measure it (left /right , up/down )?
What are the upper and lower wing incidence set at ?
Has is been fiberglassed - What is the total weight ?
The prop (18x 6-10 ) may not be efficient enough to get the most out of the ST 3000- Try a Xoar , NX, or other quality prop to get better thrust from your engine .
When adjusting the C.G , add no more than 1/4 oz. at a time to the tail . Fly , retrim , fly , add more weight if needed - repeat as needed .
Note : Straight and level flight trim is best set at a little over half throttle .
Setting the elevator trim for straight and level at full throttle will result in the plane dropping quickly when reducing power to setup for landing .
When properly trimmed the plane will still climb slightly under full power ,but will be easier to land with a little less fighting the elevator.
In my opinion a 50 to 55 cc gas engine would be great for this plane . The DLE 55 is a light and strong engine and would use much less fuel than the ST 3000.
The firewall may need to be reinforced (another layer of ply and glassed in ) and seal the foam on the inside of the fuse with a light layer of epoxy (gas eats foam).
Old 05-12-2011, 05:52 AM
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Default RE: Byron Pitts CG

Chris,

Thanks for the reply. I will check on theprops you mentioned. I am not familiarwith them. I remember flying the plane years ago with a different prop, maybe a 20x6. Seems to me the 18x6-10 was an improvement from that one. I guess the 6-10 has more pitch near the tips which makes sense given the width of the cowling...or maybe that doesn't matter.

Setting up the elevator at half throttle is something I never would have thought about but it makes a lot of sense.

I don't know the total weight. Seems to me it was around 18 pounds but I'll have to check that. It is not glassed, just econokote over the foam. Iguess I've flown the plane maybe a total of 8-10 times. The person I sold it to never flew it, just kept it hanging in his shop. It's always been a handful for me but I love the challenge!

One other question. I have not altered the servo setup in the plane. It uses one giant scale servo for the ailerons and giant scale servos for the rudder and elevator. It seems to work OK but I wonder if separate wing servos might not be an improvement.

As far as the gas engine, I would like to make that change at some point. I eventually want to put a smoke system in this plane but I would be hesitant to do that until I have all the basic flying stuff worked out.

Attached is a photo of the plane taken back in 1993.

Thanks again!
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Old 05-12-2011, 07:05 AM
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Default RE: Byron Pitts CG

fgibson ,
The weight shouldn't be a problem if its covered in econokote . I prefer the econokote over fiberglassing because of the weight savings.
I have always used seperate servos in the lower wing panels . I was never impressed by the torque tube setup on the Byrons .
The elevator and rudder setup works ok but I prefer to use pull/pull on the rudder and individual servos for the elevator halves mounted in the rear .


Old 03-10-2015, 06:28 PM
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Using a DLE 55ra. Anyone have the mounting measurements? I could also use a cowl. I acquired my kit, nib, last year w no cowl👎. I'd KILL for a Byron cowl but have heard that the GP or even FS Sheber will fit. Any confirmations on this? Thanks a ton guys
Old 03-10-2015, 06:31 PM
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FS has a number of 1/3 scale cowls in different styles available. The Sheber is my favorite.

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