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Insatiable Need for Speed!!!!!!!!!

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Insatiable Need for Speed!!!!!!!!!

Old 12-03-2002, 05:04 PM
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matchlessaero
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Default Insatiable Need for Speed!!!!!!!!!

After pushing my Caliente to 91 MPH, I realized that I just had to push it further. 100mph is only 9mph away! Unfortunately, I have to find something to get it there.
I thought 'what alternatives are there?' -- I've gotta get more rpms with the same prop, spin more pitch at a similar speed, or build a cleaner airplane or a combination of all the above.
I am already working on the design for the cleaner airplane, but to get more rpms or swing the bigger pitch, I needed more power. To do so, I could do some more motor work, but it would probably only be good for another 750 rpms at best. I could go with more nitro, but would still probably only get 750 more. Final thought was to build a tuned pipe to fit the little .049 I am running. Lots of work, but the gains could be great.
I remembered a construction article by Jerry Bradshaw written in the early eighties about how to build your own half-a tuned pipe for teedees. 12 years ago, Jerry had mailed me a copy of his construction article, and a letter with some good hints on how to do it. Using his info(2weeks ago), I went to work. His dimensions were not right for the engine I am mounting the pipe on, but they were a great starting point.
Now after a couple of weeks of work, and a failure or two, I have finally constructed a tuned pipe that fits the engine I have been running on my Caliente.
I have not yet flown it, only test bench running. So far, the results are: running with the same prop that went 91mph, I ran the engine without the pipe- ran at 21,700rpms. I then added the exhaust header I made(looks like a tiny Mac's header)- engine ran at 22,500. Finally, I installed the pipe and opened the needle approximately 1 turn. After starting, the engine surged violently up and down the tach needle. A pinch of the line brought it almost up on the pipe. A little more needling, 1 more pinch and Screammmmmmmmmmmmmmmmmmmmmmmmmmmmmm! 26,200 RPMS!!!!!!!! (on the same prop, fuel, plug, etc) That is a 4,500 RPM gain and the sound is AWESOME: )
I did not believe the numbers, so I shut everything down and repeated the test. Same results at each stage.

I have no idea how it will behave in the air, but I am hopeful. According to the simple math I have done, the rpm gain from the pipe should be enough to push it over 100mph's. I may have an opportunity to fly it as early as this weekend.

I don't have a digital camera, but I will post pics as soon as I can if anyone is interested.

Wish me luck!
Old 12-03-2002, 05:32 PM
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Default Insatiable Need for Speed!!!!!!!!!

First off - I wish you LOTS of luck!

Secondly, any chance I can get a copy of that article on making pipes?? PULLEEEESEE!?

Andrew Coholic
Old 12-03-2002, 06:38 PM
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Default Insatiable Need for Speed!!!!!!!!!

Just wondering......What prop are you running? Remember, you may need to tune a bit rich to fly right, cause it will unload after the first turn and really GOOOOOOOOOOoooooooooooooo!!! See ya!
Old 12-03-2002, 09:44 PM
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Default Insatiable Need for Speed!!!!!!!!!

VERY NICE

pic? please please and please?
Old 12-04-2002, 04:56 AM
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Default .

Thanks AJ, I am pretty happy with the results so far, but the proof will be in the flight characteristics. Check out the post I put up called 'Awesome Link'. In the search section, put in 1/2A tuned pipe and you should get the articles (2 part). I will try to find the issue date and year for you.

2fast, I had the same thoughts about the needlesetting. I fully expect the in air needle setting to be different than the test bench needle. I figure it will unload a pretty fair bit. The prop I am running is a modified APC that pitches at about 4", and 4.5" dia.

Working on pics, but just have a 35mm, so I have to get them developed.

While talking with Dickeybird the other day, he reminded me that Martin Hepperle had a Java Tuned Pipe calculator on his website. I believe I am going to build another header and pipe according to the dimensions from the calculator (it is really for engines on FAI fuel, but I figure it might yield a better pipe, and they don't take that long to build, so no much to lose...)
Old 12-05-2002, 01:15 PM
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Jeff Leavitt
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Default Insatiable Need for Speed!!!!!!!!!

Hi Matchless,

I'm not having too much luck doing the search for the tuned pipe article. My system is painfully slow as is my internet connection. I've tried the 1/2a tuned pipe search and a search on Jerry Bradshaw with no luck. Could you give me a hand here? Thnx. Jeff....
Old 12-06-2002, 01:36 AM
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Default Insatiable Need for Speed!!!!!!!!!

Ok, I am gonna try to post the link to the article.

May not work, but here goes---

http://216.37.26.18/ama/resultsimage_article.htm
Old 12-06-2002, 01:43 PM
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Jeff Leavitt
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Default Insatiable Need for Speed!!!!!!!!!

Matchless,

You a nica man.... But, no joy.... Methinks the sign on is killing the link. Could I impose on you for something simple like a month and year to look for? I think I can get there from that.... Rgds, Jeff......
Old 12-06-2002, 07:14 PM
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Default Insatiable Need for Speed!!!!!!!!!

No problem Jeff, I found my copies under all the stuff on my workbench, and it appears they are the Control line speed articles for April and June of 1981 written by good ole Gene Hempel.
I figured the link would not work, but it was worth the try. : )

I took pictures last night and plan to have them developed this weekend. I also went ahead and mounted the pipe to the plane. The next one (Muy Caliente?) will have to have the engine mounted on an angle to allow the pipe to run down the side of the fuse or over the top. Right now it sits at a somewhat drag inducing angle.

One other cool note----- with the pipe on it, it makes the coolest deep noted sounds when flipping the prop. Like a tiny Rossi 40 on a pipe... hehe.

BTW Jeff, I assume you are gonna put one on a VA. I don't think the manifold in the article or the one I figured out will fit the VA, but if I remember right, you have the advantage of rear exhaust on your VA's : ) The manifold I designed would work quite well with a Norvel though (OMG! did I just type that word:O )
Old 12-06-2002, 07:19 PM
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Default Insatiable Need for Speed!!!!!!!!!

Norvel used to sell a tuned pipe, one of which I have. The pipe consists of a straight pipe with a length of Silicone hose which you pinch at several different points until you find the maximum RPM, then use a zap strap to keep the pipe pinched at that point. I haven't tried it yet.
Old 12-07-2002, 09:24 PM
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Default 1/2a speed

I'm glad to see a purist. A real .049 going fast. Many in this forum just strap a larger engine to a little plane and go fast and furious. Reflexes are all thats needed. Getting a real 1/2a to go fast is science and persistance. Congrats.
Old 12-08-2002, 02:54 AM
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Default Update.....

Thanks Mike. It is hard, but fun.

I ran the engine again today, and I can tell that the plug is beginning to foul due to aluminum deposits on the element. (when you pull the glow plug heater from the engine, it sags heavily when not yet on the pipe.)

After mounting the engine, I zip tied everything in place just like on a normal set up. Unfortunately, the pipe is extremely sensitive to length. So I popped the rear zip tie on the little silicone connector I am using, and pulled the pipe out 1/8". That got the engine running right again.
I refueled, and launched. The engine was running VERY strong. No needle problems like I encounter on this engine without the pipe. The engine is definitely much stronger/higher in rpm in the air, and unloads a fair bit as well . I am fairly well convinced now that I will get it past 100mph on the next opportunity in front of a radar gun.

The bad news was that I did not put a new zip tie on the pipe at the silicone connector. After about a minute and a half of flight, I brought the plane across the field (about 20yds from the runway) on a very high speed pass. All of a sudden, I saw something fall from the plane, and the engine sagged several thousand rpms.
After rolling the plane inverted to kill the engine an landing, I ran out into the freshly disked cornfield and searched for 45 mins for my precious pipe. After finding it, I went back to the pits to inspect the plane again and found that the header had literally begun to blow apart in the air just past the welds. Same thing happened to the first header I made when I ran it unsupported without the pipe.

Back at the house, I spent the afternoon making a nicer header with better welds(big wide fillets)/prettier bending in the tubing and I have already put everything back in place on the plane and test run the engine again. Not any faster, but the header sure is prettier!

I sure hope I get to fly tomorrow mornin'................

Pics are coming soon..............
Old 12-09-2002, 12:37 AM
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Default Good and Bad.....

Well the wife wanted to go X-mas shopping so I got to go fly. That began the good.

After getting to the field, I fueled up the plane, and got her ready to go. With the new plug, she started up and came up on the pipe with a zing. In the air, the plane felt strong, but I could tell it was not turning any more than about 23k, so I rolled it over to kill it, and brought it in.
The header had already begun to crack slightly, but at this point, I figured what the heck, was I gonna break it?
I started her back up and got a much better needle this time. MUCH stronger this time. Engine was turning in the 26k range on launch, and began to unload in the air. I made many passes back and forth and some with dives on either end. The plane is much faster, how much I don't know, but definitely faster.

Then the bad came..... With 30 seconds of fuel left, the header broke away completely. At that point, the pipe skewed sideways causing the plane to yaw violently. I began to fly the plane over the runway as it sagged, and tried to do some rolls over the runway to shake the pipe loose. I ended up landing on the far end of the runway. Other than the broken header, the plane came out without a scratch.

Very promising. Time to build a stronger header.

Anyone know of a supplier for aluminum tubing that may be stronger (9/32" diameter) ?
Old 12-09-2002, 01:13 AM
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Default Insatiable Need for Speed!!!!!!!!!

Matchless,
Doesnt K&S have a wide selection of aluminum tubing? When I get to a real hobby shop, I usually see a good selection with some thicker walled stuff.

NOW, I am going to offer you my services here, free of charge, in order to promote "pushing the envelope" so to speak.

As you may know I have a lathe and I also have lots of aluminum, 6061-T6, 2011-T3 and some 2024-T6 I believe in 3/4" diam. The 2024 stuff is very strong, but I am sure normal 6061 will do the trick. 2011 I use for pistons as it has less movement with heat if I am not mistaken.

You tell me what size (inside diam, outside diam and length) of tubing you need for your header (and any steps, etc) and I will make you one up, OK?

I want to see you hit >100MPH mark, but you will need to keep that exhaust set up intact!

Let me know...

Andrew
Old 12-09-2002, 02:40 AM
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Default Insatiable Need for Speed!!!!!!!!!

Matchless,

I also have some super stuff I bought from a foundry supply house (where I get my casting sand and other stuff) its a German made aluminum repair formula that is unbelieveable. Its about 96% aluminum and some kind of synthetic binder. Its sold to foundries for repairing casting flaws. It will withstand 700 degree heat, and after curing machines just like aluminum (since it is basically all aluminum). I use it for making headers and fixing engine exhausts. It will take the heat and stand up. If you need help making the header/pipe junction I can also help.

FAiling that, I can allways make a wooden pattern and snad cast you a one piece header from aluminum to your specs.

I want you to succeed buddy!

Andrew
Old 12-10-2002, 02:34 AM
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Default Insatiable Need for Speed!!!!!!!!!

Wow AJ, that is one heck of an offer. I really do appreciate the support.

I will send more details in a PM...
Old 12-11-2002, 02:28 AM
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Default Another idea

A couple of us 1/2a fanatics are working on a bolt on performance accessory that won't increase displacement but will add HP. Sent Matchless aero a PM.
Old 12-11-2002, 02:49 AM
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Default Insatiable Need for Speed!!!!!!!!!

Matchless -sent you a PM.

Mikesell, why not share with ALL of us?

AJC
Old 12-12-2002, 01:08 AM
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Default Guys, I got both of your PM's/Time for Pictures!

Plane with pipe
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Old 12-12-2002, 01:44 AM
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Default From the right.

.
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Old 12-12-2002, 01:46 AM
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Default better pic from right hand side

Gives a pretty good idea of pipe dimensions and shape.
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Old 12-12-2002, 01:48 AM
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Default From Above

Gives a good idea of the shape of the bend in the header.
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Old 12-12-2002, 01:52 AM
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Default Pic of the first header.

This was my first header. The second header I built lasted 10 more minutes worth of running, and was much prettier in bend and weld quality. You can see the port has been matched and shaped for better flow from the engine.
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Old 12-12-2002, 02:28 AM
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Default Insatiable Need for Speed!!!!!!!!!

Matchless - I can definitely machine you a one piece header, with the bend and all. That will never ever break I promise you.

Just need a sketch with dimensions!

Andrew

PS what engine is it?
Old 12-12-2002, 04:01 AM
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Default Insatiable Need for Speed!!!!!!!!!

This is for anyone that wants something to start with


All measurements are inside dimensions....

Aaron
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