Re: Goldberg Li'l Jumpin Bean build thread (Finished!)

PV Pilot Sat Sep 15, 2012 1:33 am

Metal backplate motor?

Ivanhoe Sat Sep 15, 2012 8:24 am

cribbs74 wrote:
happydad wrote:Ron: did you ever figure out why the plane was nose heavy ? or was it less nose heavy when finished and covered ?happydad

Less nose heavy, but still nose heavy.......... As much as I don't want to add weight I am going to have to if I want this thing to stunt well.

Ron

I have noticed that the nose on the Brodak kit is a lot longer than on the original Goldberg design, this may account for the nose-heavy balance, no idea why they lengthened it (compare with my pic of my original design)
Have you positioned the cylinder on the inside for any particular reason?

Wilf

Ken Cook Sat Sep 15, 2012 8:53 am

Keeping the cylinders turned outboard was typical for many years. For one , it assisted in tip weight theoretically speaking. The problem with having a outboard cylinder or even a upright cylinder is the fact that fuel is being thrown into the plug causing a burp. This is very apparent in a Fox.35 and some will say it's a myth. I had a long discussion with Larry Renger in regards to the inboard mounted cylinder. It actually in my opinion improves the run through all the maneuvers. The plug isn't getting fuel thrown at it and it keeps running steadily even through the outsides. Before you decided to turn it outboard, I would seriously try it as is. The Hyper Viper in addition came with an inboard mounted cylinder. Ken

**RknRusty** Sat Sep 15, 2012 9:28 am

Masterful job, Ron. The wingtips look great too. Those are the hardest part of covering. I think your leadouts are a good bit farther rearward than mine. I never got back to you with the CG position. I'll have it in a few minutes.

Ken Cook wrote: Keeping the cylinders turned outboard was typical for many years. For one , it assisted in tip weight theoretically speaking. The problem with having a outboard cylinder or even a upright cylinder is the fact that fuel is being thrown into the plug causing a burp. This is very apparent in a Fox.35 and some will say it's a myth. I had a long discussion with Larry Renger in regards to the inboard mounted cylinder. It actually in my opinion improves the run through all the maneuvers. The plug isn't getting fuel thrown at it and it keeps running steadily even through the outsides. Before you decided to turn it outboard, I would seriously try it as is. The Hyper Viper in addition came with an inboard mounted cylinder. Ken

I remember that discussion. I've been planning to try the inboard cylinder next time I mount an engine. My engines always bog slightly, especially the Bees, during tight turns.

**Cribbs74** Sat Sep 15, 2012 9:29 am

PV Pilot wrote:Metal backplate motor?

Funny you mentioned that. I removed the metal backplate of my BRM to get it to balance. I don't really want totake it off of this one too.

It took 4 dimes on the tail to balance this one.

**RknRusty** Sat Sep 15, 2012 9:31 am

The CG on my plans is 1-1/8" behind the LE.

**Cribbs74** Sat Sep 15, 2012 9:32 am

Ivanhoe wrote:
cribbs74 wrote:
happydad wrote:Ron: did you ever figure out why the plane was nose heavy ? or was it less nose heavy when finished and covered ?happydad

Less nose heavy, but still nose heavy.......... As much as I don't want to add weight I am going to have to if I want this thing to stunt well.

Ron

I have noticed that the nose on the Brodak kit is a lot longer than on the original Goldberg design, this may account for the nose-heavy balance, no idea why they lengthened it (compare with my pic of my original design)
Have you positioned the cylinder on the inside for any particular reason?

Wilf

Hey Wilf,

Yes, Ken suggested I do that on a previous build for the reasons mentioned above.

Ivanhoe Sat Sep 15, 2012 9:34 am

Ken Cook wrote: Keeping the cylinders turned outboard was typical for many years. For one , it assisted in tip weight theoretically speaking. The problem with having a outboard cylinder or even a upright cylinder is the fact that fuel is being thrown into the plug causing a burp. This is very apparent in a Fox.35 and some will say it's a myth. I had a long discussion with Larry Renger in regards to the inboard mounted cylinder. It actually in my opinion improves the run through all the maneuvers. The plug isn't getting fuel thrown at it and it keeps running steadily even through the outsides. Before you decided to turn it outboard, I would seriously try it as is. The Hyper Viper in addition came with an inboard mounted cylinder. Ken

I suppose that it would be easier to handle plug connector and needle that way if you are left-handed, otherwise I think it would prove a little awkward, certainly I could never handle a model with the cylinder that way, having all my experience back in the day with diesels, they were positioned toward the outboard side so that you could keep your left hand on the compression screw while flicking the prop, and seeing it the other way just looks totally "wrong" to me!

**Cribbs74** Sat Sep 15, 2012 9:51 am

RknRusty wrote:The CG on my plans is 1-1/8" behind the LE.

Lol, I thought it was only 1" that is gonna make it worse!

**Cribbs74** Sat Sep 15, 2012 10:38 am

Ivanhoe wrote:
Ken Cook wrote: Keeping the cylinders turned outboard was typical for many years. For one , it assisted in tip weight theoretically speaking. The problem with having a outboard cylinder or even a upright cylinder is the fact that fuel is being thrown into the plug causing a burp. This is very apparent in a Fox.35 and some will say it's a myth. I had a long discussion with Larry Renger in regards to the inboard mounted cylinder. It actually in my opinion improves the run through all the maneuvers. The plug isn't getting fuel thrown at it and it keeps running steadily even through the outsides. Before you decided to turn it outboard, I would seriously try it as is. The Hyper Viper in addition came with an inboard mounted cylinder. Ken

I suppose that it would be easier to handle plug connector and needle that way if you are left-handed, otherwise I think it would prove a little awkward, certainly I could never handle a model with the cylinder that way, having all my experience back in the day with diesels, they were positioned toward the outboard side so that you could keep your left hand on the compression screw while flicking the prop, and seeing it the other way just looks totally "wrong" to me!

I haven't had a problem with it. I attach the clip and just wind the prop and hold the plane the usual way. It would be a pain if your glow clip had a loose fit.

**Cribbs74** Sat Sep 15, 2012 10:50 am

Rusty,

Didn't see your comment about the leadouts. They are positioned exactly as the plan depicts. I took the tip and marked the location on it when it was laying flat on the plan. When I hang the plane by the leadouts the nose points slightly downward. I decided to set it up without rudder offset per Ken's suggestion.

PV Pilot Sat Sep 15, 2012 12:39 pm

cribbs74 wrote:Ok, Finished, I am happy with this one. I see where I could have done better, but the reality is I will turn it into kindling anyway........

Jeeez!,,come on Donny Doomsayer,,have a big cup of confidence and let it rip!

**Cribbs74** Sat Sep 15, 2012 1:10 pm

PV Pilot wrote:
cribbs74 wrote:Ok, Finished, I am happy with this one. I see where I could have done better, but the reality is I will turn it into kindling anyway........

Jeeez!,,come on Donny Doomsayer,,have a big cup of confidence and let it rip!

Ha! That was my attempt at being positive Keith. I did say I was happy with it! Wink

I am learning to stunt so what I was attempting to say is I am not going to focus on the imperfections as I will probably damage it anyway.

PV Pilot Sat Sep 15, 2012 1:21 pm

cribbs74 wrote:
PV Pilot wrote:
cribbs74 wrote:Ok, Finished, I am happy with this one. I see where I could have done better, but the reality is I will turn it into kindling anyway........

Jeeez!,,come on Donny Doomsayer,,have a big cup of confidence and let it rip!

Ha! That was my attempt at being positive Keith. I did say I was happy with it!

I am learning to stunt so what I was attempting to say is I am not going to focus on the imperfections as I will probably damage it anyway.

HeHeHe! I seen that. No worries,,they make them every day.

**RknRusty** Sat Sep 15, 2012 1:28 pm

cribbs74 wrote:Rusty,

Didn't see your comment about the leadouts. They are positioned exactly as the plan depicts. I took the tip and marked the location on it when it was laying flat on the plan. When I hang the plane by the leadouts the nose points slightly downward. I decided to set it up without rudder offset per Ken's suggestion.

I think they need to be that way. When I remake my Bean I'm going to re-position them more rearward. I shifted the leadouts on the Chopper and it made a difference in the line tightness.

**RknRusty** Tue Sep 25, 2012 8:48 am

cribbs74 wrote:
RknRusty wrote:The CG on my plans is 1-1/8" behind the LE.

Lol, I thought it was only 1" that is gonna make it worse!

Ron, I was wrong! The CG is 1" from the LE. I'm sorry, I screwed up, I hope I didn't cause you to mess anything up. 1/8" difference would make it snappier, but maybe too much so.

gcb Wed Sep 26, 2012 9:42 am

If at all possible, make the wingtip leadout position adjustable. Unless you have the same engine power and offset, rudder offset, and line drag (length, steel dia., dacron, fishing line), any suggestions, including placement per plans is only going to be ballpark when you trim for stunt flying. Back too far and you may lose line tension as you get higher in the circle. Remember, when learning stunt you need to consider the entire hemisphere, rightside up or upside down.

You must consider your first few planes expendable. We all make building mistakes and we try to improve next time. Wait 'till you start thinking, "Shucks, I know better than that" when you have made a mistake...that hurts! Sad

George

SuperDave Wed Sep 26, 2012 10:36 am

As Ron's learns to "stunt" his first stunt is learning to dodge the trees in his yard.

lol!

PV Pilot Wed Sep 26, 2012 10:53 am

gcb wrote:

You must consider your first few planes expendable.

George

Good words George. They might sting a little bit, but very true.

SuperDave Wed Sep 26, 2012 10:59 am

Soothing words for the "crasher":

"Failure can become success if you learn from it".

It's like learning to ride a horse. If you get thrown "man up" and give it another try.

YEEEEEEHA! lol!

gcb Wed Sep 26, 2012 12:51 pm

If you built it once, you can build it again. It may be a little heavier and uglier from patches and repairs but almost any crash can be repaired...and, not all crashes require repairs.

The best attitude is to assume that at one point it WILL need fixing. Been there 'n done that...'n done that, ...'n done that... Smile

George

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