jlkonn

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I have a friend with a "dream"...everyone needs one of those right?

He's an elderly gentleman that owns a couple planes that I doubt he will ever fly again.
He also has a couple partially completed projects. One is a Pitts S-1. His dream is to
finish it under the Light Sport Aircraft rules. Right now the book says the stall speed is
way over the 45 knot LSA rule. He thinks he can add wing span and lower it. He also
wants to mount an O-200 for the engine.
Before the nay sayers jump in with the "you can't do that"! comments anyone with aeronautical
design experience please give a definitive yes or no if you can and why. I need something I can
take back to him. He doesn't have internet access and has made me promise to at least try to find
out.
Thanks!
JLK

normgoyer

Elderly gentleman shouldn't fly Pitts type aircraft. Tell him what he wants to hear as he is prorbably going to do it anyway. Any change of wing area and power package will completely change the flight characteristics and he will become an elderly test pilot. Norm

not a good combination

aldentwc

the first thing i'm going to say is does he wanna die happy, and my second question is what kind of motor is in it now because a O-200 may not provide the extra umpgh he is looking for. And i think an old dude would make a great test pilot they have already lead a good life

jlkonn

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Thank you Alden.
The whole point is he has a dream.
I don't think he will ever get the plane finished but something to live
for and look forward to and "dream" about.
He already owns a completed S1 but it's been a while since he's flown it and
doubt he ever will again. The plane we're talking about is one he's not completed.
Thanks again for understanding the point of my question.
JLK

aldentwc

yeah i am an airframe mechanic who was never able to work on airplanes... stupid 9-11 anyway they are my passion and where i don't know much about sport planes i know a fair amount about the concept. one of the things you can do although it may look weird is to add winglets. I do know that they "extend" the wingspan by a foot or so by limiting the wind slip over the end. especially with a wing profile like that you can capture the full effectiveness of the wing without compromising the structure at all. if you are going to address the structure to extend the wings you need to make it much stronger than you think or it will crumple under heavy stress (acrobatics) if he is just looking to fly the thing without whipping it around it won't need to be reinforced. also do you know what kind of construction the wing is currently made of if you could get a picture of the inside it would greatly help me to make suggestions to you as everything i say now is just nice in theory.

it's best to live a full life first, but to go out in a blaze of glory that would be bliss
Alden

TFF

The original homebuilt was designated S-1C; the C for continental 0-200, but everyone wanted more power so most went with 150 hp. The original S-1 first flew with 55hp engine upgraded to 90 hp Franklin, so if he does it right he ends up recreating the first kind. Adding to the wingspan will be hard for one main reason the top wing with the sweep will not like it without changing the sweep; the CG otherwise woud have to be changed. As to age and ability, I have an aquantence who is the son and they had father /son Pitts. The son told me his father was still landing his on the runway at age 80 and he at 55 would not do it because he did not like the challange and he is a test pilot.

TFF

http://www.airbum.com/Pitts/PirepPittsReplica.html

jlkonn

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Thanks again Alden.
The wing is wood construction...spar and all.
I don't know if I can get pix but I'll see what I can do.
Your winglet idea is a good one. What I need to do is stear him
to someone that can tell him definetely how he needs to add of what.
JLK

aldentwc

well wood is both good and bad. the good news is you can splice an extension to the existing wood spar and then build up some more wing ribs recover it and make a longer wing, the bad news is the only way to test the spliced wood spar strength is to break it... this is not absolute necessary, but i'm paranoid. but basically what you do is cut the end of it at an angle of about 15 degrease (1 rise for every 15 across minimum) which makes for a long shallow cut across the spar cut a new spar piece to add onto it at the same angle glue add a lot of pressure and let it dry over a weekend. Also you need to install reinforcing plates.thin reinstall the new ribs to and spar of the new length. the best thing to do is to do test spars first. and then bend them till they break until you can achieve a standered bend. IE take a new regular spar clamp down one end and bend it till it breaks and mark that spot (usually on the floor) then cut a spar in half glue it back together after cleaning up the cut and see if you can get back to that point or exceed it.(once again not necessary but i wouldn't fly without doing this) on another note when you make the cut try not to sand it. I have done this on smaller planes with only 3" spars (models) and i make cuts using a hand wood saw and a miter box, and then use a razor blade to trim into it's final position. it is a long and argues process, but provides the best bond. try to avoid sanding as it leaves tiny particles inside the wood poors which weakens the joint. I have successfully on a model spar cut it and sanded it to the right dimensions and then used an exacto to scrape down to new wood, but would not trust that process on a plane i was going to fly personally unless i could reinforce it in some other way or start packing a chute...

alright i found what i was looking for had to dig it out of the back of the garage but i found my AC 43.13-1b/2a book (acceptable methods, techniques, and practices - aircraft inspections, repair & alterations) but in section 1-40 defines splicing of spars should be able to find this online, but if you need me to copy it into here let me know and just to warn you it was written by lawyers so it is hard to understand and very descriptive, but not in a helpful way.

I hope all of this helps and be sure to take pictures it has been a long time since i have worked on a "real" airplane so it's good to see i still remember something.

jlkonn

My Feedback: (1)

OK, Alden.
Thanks!
I'll pass this along and see where it leads.
If I need to take pictures for further I'll do it.
Thanks again!
JLK

aldentwc

no i was just asking you to take pictures so i can see the project come along it's winter time it's not like i have much else to do

jlkonn

My Feedback: (1)

Alden,
I'm in Iowa so it's going to be winter X 2 here!
I hate it!
JLK

aldentwc

jsut think warm thoughts also a heated hanger might help