Brodak 38 Special trimming....

[Chris Fretz]

So I finally got out last Sunday to do some test flying with the 38 Special. It's not bad, it could be better thought! The Outboard wing is high upright, so I put some more tip weight in. I only had a 1/2 ounce in it to start with, by the time I was done for the day it ended up with 1.5 ounces. It also comes out of the sky like a brick so I put some tail weight on it, think i only had 1/2 ounce sticky weight. It either wasn't enough or not what it needs.  It doesn't do a tight loop. After all that I got it upside-down and to me it seems the Outboard wing was down but I could be wrong it's hard to tell inside the circle. I guess I'll have to put a trim tab on the Outboard wing I just hope it doesn't make the wing crooked upside-down. After looking at the video it seems level upside-down. Kinda hard to see in the video. I think I had like 5 incidence meters on it when i was building it. I don't think they are accurate but still better than my eye.

What do you guys think?




Chris

[Chris Fretz]

Picture.

[Chris Fretz]

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[mike londke]

Looks great Chris.

[Chris Fretz]

Looks great Chris.

Thanks Mike! Did yours glide very well?

[mike londke]

Thanks Mike! Did yours glide very well?

Nope.

[Dennis Toth]

Chris,
Tom Dixon designed the original and they flew very good. Maybe you could send him a PM and get some setup tips for this ship.

Best,   DennisT

[Dan McEntee]

So I finally got out last Sunday to do some test flying with the 38 Special. It's not bad, it could be better thought! The Outboard wing is high upright, so I put some more tip weight in. I only had a 1/2 ounce in it to start with, by the time I was done for the day it ended up with 1.5 ounces. It also comes out of the sky like a brick so I put some tail weight on it, think i only had 1/2 ounce sticky weight. It either wasn't enough or not what it needs.  It doesn't do a tight loop. After all that I got it upside-down and to me it seems the Outboard wing was down but I could be wrong it's hard to tell inside the circle. I guess I'll have to put a trim tab on the Outboard wing I just hope it doesn't make the wing crooked upside-down. After looking at the video it seems level upside-down. Kinda hard to see in the video. I think I had like 5 incidence meters on it when i was building it. I don't think they are accurate but still better than my eye.

What do you guys think?




Chris

       All the 38 Specials I have seen fly looked to fly just fine. You need to have someone sight the plane from out side the circle for wings level up right and inverted.  If the outboard wing was up in upright flight, it could have been a misalignment, and now you have a lot of tip weight in it making the wing tip down in inverted flight. If you are like me, you have to focus much harder on inverted flight and it's difficult to look st small details while inverted. You have two wings on the are plane and that makes alignment twice as important and twice as difficult. It may make a difference which wing you put the weight in.!!??? Start over with your bench trimming and check all alignments, including , I think, some negative incidence in the top wing. Then recruit some help to sight down the model for you from outside the circle while you fly as smoothly as you can. Since it is a biplane, it will be a bit more draggy and nothing you can do about a poor glide other than being ready when the engine quits with a bit of down control and an abbreviated landing approach. These fly well enough to be competitive in regional intermediate and advanced classes of competition, I feel, so stick with it. I have a kit stashed and been thinking of changing the shape to look like a Stampe or some other biplane just for fun. Good luck with it.
   Type at you later,
  Dan McEntee

[john e. holliday]

I have a 38 Special that has quite a few flights on it.  Flies better than I do.  I would suggest that if wings are straight, no warps and incidence is identical, try hanging the plane from the lead outs.  The wings should be straight with the lead outs.  May have to adjust the guide to get them straight.  Also biplanes are not known to glide like a normal stunt plane, but mine does a good job of landing.  No full lap gliding to touch down though with out a little help on pulling it like a racing plane.

By the way, plane looks great.

[Dave Hull]

Beautiful looking plane.

[Chris McMillin]

When the engine quits with a biplane your plan should be to whip it to a touchdown. When flying real ones it takes a steep glide to hold speed and the model does too. You provide thrust by whipping.
Chris...

[Chris Fretz]

       You have two wings on the are plane and that makes alignment twice as important and twice as difficult. It may make a difference which wing you put the weight in.!!???

It sure is twice as difficult.... I just put the weight where the plans called for in the bottom wing.

I have a 38 Special that has quite a few flights on it.  Flies better than I do.  I would suggest that if wings are straight, no warps and incidence is identical, try hanging the plane from the lead outs.  The wings should be straight with the lead outs.  May have to adjust the guide to get them straight.  Also biplanes are not known to glide like a normal stunt plane, but mine does a good job of landing.  No full lap gliding to touch down though with out a little help on pulling it like a racing plane.

By the way, plane looks great.

Thanks Doc!

Beautiful looking plane.

Thanks!

When the engine quits with a biplane your plan should be to whip it to a touchdown. When flying real ones it takes a steep glide to hold speed and the model does too. You provide thrust by whipping.
Chris...

Crazy, I would of thought 2 wings the better it would glide. Good to know though!

[Dane Martin]

Crazy, I would of thought 2 wings the better it would glide. Good to know though!

Twice the lift, twice the drag, half the forward movement in a glide... lol . Completely made up. But, definitely less glide. My triplane flys great. But when the engine dies, there's no leading it anywhere. It's time to land now!

[Walter Hicks]

Tom Dixon wrote and Article in either AMA or Flying Models on how to build and trim the 38 Special . I am sure he can find it and send it to you.
It was very specific on how to hang it by the leadouts and adjust the trim .

[Dave Hull]

May 1993 Model Aviation.

Dixon says he put 1/2 oz. of tipweight in the top wing only.

Now if I could work up the enthusiasm to paint mine....

McDivot

[Chris Fretz]

Twice the lift, twice the drag, half the forward movement in a glide... lol . Completely made up. But, definitely less glide. My triplane flys great. But when the engine dies, there's no leading it anywhere. It's time to land now!

Made up or not it sounded good lol

May 1993 Model Aviation.

Dixon says he put 1/2 oz. of tipweight in the top wing only.

Now if I could work up the enthusiasm to paint mine....

McDivot

Does it say what length lines he was using?

[Steve Helmick]

Only one I know of locally, and I've never seen it fly, because the (EXPERT) flier/builder couldn't get it to fly to his expectations and hung it on the wall to gather dust.

What have you got in yours for power? Sounds and looks like a .46LA, or maybe a .40LA? I was actually surprised that yours glided as far as it did...about 3/4 lap? Couldn't quite see the touchdown on this laptop. Line length depends on power available, prop and airplane weight, so how much does your pretty 38 Special weigh?  Steve

[Chris Fretz]

Only one I know of locally, and I've never seen it fly, because the (EXPERT) flier/builder couldn't get it to fly to his expectations and hung it on the wall to gather dust.

What have you got in yours for power? Sounds and looks like a .46LA, or maybe a .40LA? I was actually surprised that yours glided as far as it did...about 3/4 lap? Couldn't quite see the touchdown on this laptop. Line length depends on power available, prop and airplane weight, so how much does your pretty 38 Special weigh?  Steve

Thanks Steve
Right now with 3/4 oz in the tail and still like 1 3/4 oz in the wing its sitting at 46oz

I'm running LA46 with 12.25 x 3.75 prop on 61ft lines .

I had it out this past weekend, it's not bad flying. Maybe not Turning as tight as I'd like but not bad.  I think i squeezed 3/4 lap out of her again the last time I landed.

Chris