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Nov 26, 2007, 04:07 PM
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bosley's Avatar
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30" P-40 stick and tissue type scratch build.**Short Kits Available**


This thread started out as a question about how important the notches are when building a stick and tissue style model. It was answered quickly and kinda morphed into a little build thread.

As the title says how important are the stringer notches in a former when we are talking about stick and tissue style airplane. I have drawn up a 30" P-40 in CAD and while the stringers looked fine on the computer screen they don't run as true as I would have liked in real life.

This could be attributed to cutting everything by hand but I am wondering if I can just do away with the notches where they don't flow well and just face glue the stringers to the formers where they lay.

What are your thoughts.



Short kits now available at:

www.manzanolaser.com

Hope you all enjoy them, this has been a fun process.
Last edited by bosley; Oct 23, 2008 at 11:48 AM. Reason: changed title to reflect kit availability
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Nov 26, 2007, 04:12 PM
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vonJaerschky's Avatar
Yes, you certainly can. You may lose a bit in strength, but I don't think it will matter much with an airplane that size.
Nov 26, 2007, 05:10 PM
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portablevcb's Avatar
Yes. As long as they are glued well to the former. The notches really set the spacing and force a curve where needed. They also make it a bit easier to glue the stringers in place, but, with CA, that is not really an issue.

charlie
Nov 26, 2007, 05:19 PM
It flew once before...
jofrost's Avatar
This is good to know . I have a bunch of Earl Stahl plans that show where the stringers should go , but does not indicate if it is supposed to be a notch or glued to the outside of the former ? I often wondered if it mattered
-John
Nov 26, 2007, 05:37 PM
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bosley's Avatar
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Thanks Fellas.

anyone else have any thoughts on the matter.

I will post up some pics of where I am at once I get the baby put down for the night.


Bosley
Nov 26, 2007, 05:38 PM
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SKY KING's Avatar
I questioned the same thing a while back when building a Peter Rake plane - it resulted in no strength issues and simplified stringer placement.
Nov 26, 2007, 05:57 PM
Suspended Account
I consider the lack of notches as a good design practice. It allows you to place the stringer where it or you naturally want it to go. This puts a lot less stress on the airframe during building and give you a chance to make a straight fuselage.
I have tried to force stringer into the pre cut slots (notches) only to have stringer that look more like a snake than an aircraft structure and it results in bananas for a fuselage.
Also the lack of bulkhead (former) material at the stringer level helps to eliminate the starved horse look often seen in film of fabric covered models I do leave or build up the former to the stringer level if I need an area for the covering to purchase (mount, stick or bond).

A secondary benefit is if you want to sheet (large continuous piece) or plank (like a ship) the former are pre-sized. I also find it helpful not to have the former in the way when doing balsa fill between the stringers.
Hope this helps,
Konrad
Last edited by Konrad; Nov 26, 2007 at 06:11 PM.
Nov 26, 2007, 07:37 PM
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bosley's Avatar
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Pics of the project so far.


That was a lot of notches to cut by hand.

What do you think? Keep going or send the files off to Charlie so I can try again with the current notch settings? This time laser cut and a bit more accurate.

Bosley
Nov 26, 2007, 07:51 PM
Suspended Account
Bosley

It looks like a counting error. Prior to the stringer sway I count 2 notches open after the sway I count 3 notches open. Is this by design, more stringers coming into play?

Looks great,
Konrad
Nov 26, 2007, 07:52 PM
a.k.a Maltone
Pat Lynch's Avatar
Bosley, while I cant speak for the aircraft you are modelling, many real 'planes finish up with wonky stringers! Perhaps not so much where metal frames are used though

You model so far looks superb!

Pat
Nov 26, 2007, 08:15 PM
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glewis's Avatar
I would cut the vertical pieces of F8 (?) loose from the top and bottom horizontal pieces at the glue joint. Then shave a bit from the top mating surface to move the whole piece up a bit to straighten the stringers. The bottom gap can be filled with a sliver of balsa. You could always shave off all those pretty notches, but after cutting them all I would try to fix it.
Nice workmanship, that's a bunch of notches to cut!
Glenn
Nov 26, 2007, 10:06 PM
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bosley's Avatar
Thread OP
Thanks for the suggestions and thoughts. I will likely leave all as is right now and use the hand cut model as a bit of a proof of concept. I want to fly it before I spend too long trying to perfect a brick !!!!

I think I will end up adding in some additional formers in the rear to give some more support to the stringers in that area. They tend to flex a fair amount between the formers right now.

I did some more tonight. I added some more stringers, got in the parts behind the cockpit and got one shaped and filled. Also built up the vertical stab and rudder.

I was originally planning on throwing a cheapo brushless from Balsa products but I think it would rip the wings off the thing now. Any suggestions for some zoom zoom warbird type stuff at a weight of around 10-12 oz.

http://www.bphobbies.com/view.asp?id...7&pid=B1898551

Bosley
Last edited by bosley; Nov 26, 2007 at 10:12 PM.
Nov 26, 2007, 10:14 PM
Neophyte hacker
portablevcb's Avatar
At that weight a CDROM size motor would be just about right. Battery and prop for 50W would work well.

Looks good so far.

charlie
Nov 26, 2007, 10:21 PM
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bosley's Avatar
Thread OP
Glenn,

I just wrapped my head around what you suggested and it makes a lot of sense. Wish I had read it before I glued in a bunch more stuff!! At any rate I have some more decisions to make and I am fairly motivated as this is the first design I have had go from cyberspace into something I can actually hold and will hopefully fly one day!!


By the way I changed the title to

"30" P-40 stick and tissue type scratch build."

After I posted a few of these pics. Seems fitting I guess as this appears to be morphing from a question to a bit of a build thread. I will post majorish updates aas I get stuff built. I really love the look of all the stringers on these types of build.

Charlie how is the Midkiff P-47 coming along??? Looking forward to that one too.

Bosley
Last edited by bosley; Nov 26, 2007 at 10:28 PM.
Nov 27, 2007, 05:29 AM
It flew once before...
jofrost's Avatar
Bosley ,
Looking absolutely fabulous ! I have a thing for P40s and you have done extremely well capturing the shape thus far .
Now as to its size , and I'm going to guess at a wing area of lets say 160sq.
and being the light construction you may want to keep it that way . The motor you chose there is a bit bigger than what I would go with for that size/construction .
I use a Park300 E-flite on a 730mah TP3s swinging a 7x6 APC SF which gives about 65watts in a 9oz Herr Corsair with 30" WS .
Or any good CDROM type .
Keep up the great progress

Or for an affordable motor that performs really well the Silver Wonder for $15:
http://www.ncweb.com/biz/dan/Motors.html
-John


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