combatpigg

My Feedback: (3)

To raise the timing for a tuned pipe, most small glow engines need about 180 degrees of time that the exhaust port is open. By raising the port you lose torque, but gain high rpm breathing capability. If you do this, then you are usually commited to running small diameter props. You will need a degree wheel and probably an adapter to bolt the wheel to your engine. If you have a lathe and some aluminum round stock, no problem. I make an adjustable positive stop tool to establish true TDC with, you bring the piston up against it from both directions, then split the difference on the wheel marks to align the pointer. An automotive hotrod book will have a chapter about how to do this. The rest is simply to rotate the engine and take note when the opening and closing occur, and total up the degrees. to arrive at 180 degrees exhaust timing, you would need to rotate the engine to that point and scribe a line on top of the piston that is above the exhaust port. This is the line that you would take a fine tooth carbide cutter and raise the port to. Remove any burrs with an EXACTO blade, but do not radius the edge. Same goes for the intake valve, rule of thumb is 60-65 degrees ATDC is pretty agressive. The other limiting factor is the carb, if you are serious about max rpm, get a fixed venturi and use an OS .10 remote needle on a seperate bracket. For a fuel line fitting at the venturi, a tapped pressure fitting works OK for a fuel dump.

MyWay

Skull Man. Can,t tell from the picture what exhaust system you are using. Is it a tuned muffler or a full tuned pipe.
.

Camel

Just noticed your query in passing, try Weston UK Magnum R with their 50V motor and pipe, claimed 200+ and they have clocked em at our shows well in excess of that. I've had two and they are excellent, use 9x9 apc and you can easily under arm left hand launch it has so much static grunt! or for the extra 10 or 20 mph use 20- 30 % nitro shorten the pipe manifold by 1/2 inch and use a 8x10 apc bit more of a launch needed and the acceleration is down however the top speed is silly

web site http://www.westonuk.co.uk/arflist.html

Oh and it floats like a ***** act on landing diificult bit is learning when to cut the throttle so the prop has stopped, horizontaly, otherwise it costs a prop each landing!
4mins on a tank, pure adrenalin![>:]
have fun

Camel

Sorry.typo. That should be floats like a trainer then on landing any way very easy to fly slowly. When gliding keep the nose down during a turn or it will stall and spin standard swept wing stuff

evan-RCU

Camel... No way on earth you are getting 150+ on your Magnum, not even in a diving pass. 145 level is all they got, I run a 8X9 or 8X10 depending on the day and we have a couple here and they radr all the same. The 200mph claim on the box is laughable!!

MyWay

Camel and Evan RCU; Please limit your inputs to .32 and smaller engines and planes. I don't want to get this discussion off track. Thanks.

slowmo777

This is a true 200 mph plane – as an exception no exaggerated speed claims here.[sm=rolleyes.gif]

Only 1 KW of engine output is needed to get to these speeds provided that you make use of elaborated aerodynamics and the right speed prop. It’s a matter of time and lots of testing. Please do not use the layout of pylon (F3D or similar) fuselages for your next speed projects – too fat!


Regards

MJD

My Feedback: (1)

Help me out here. I googled Cyclon and was not able to locate the site. Then again, I couldn't find my keys again this morning and they were in my jacket pocket, so..

MJD

combatpigg

My Feedback: (3)

Go to the NORTH AMERICAN SPEED SOCIETY site, there are multiple links to just about anything you could want. Doug Galbreath is the CYCLON dealer.

MyWay

Slowmo 777, I have a lot of questions about your speed planes. For a start what is the smallest size engine that you are using to achieve 200 mph, and how much did the plane weigh fueled?

slowmo777

Hello,

the fibre glass fuse as well as the wing span is 82 cm. Total weight fueled is 850 grams. Area of wing is about 12 dm². You can use any top end 1.5 to 2.5 ccm piped engine, but the 200 mph mark will only be reached with a .15 sized engine. Please take a look at the modern FAI F2D COMBAT engines and if you have the cash the FAI F2A SPEED engines too (those are much hotter). F2D Combat engines must be modified to accept a F2A tuned pipe, don’t forget to adapt exhaust timing while doing that. Adjust the pipe length in order get the engine hardly on pipe on the ground – that makes sure for highest in-flight revolutions. You must use high strength props made of composite material. C/L carbon props can be tested but they don’t provide enough prop pitch for our purposes. So own made composite props are the only way to go. These should be as thin as possible to enable prop revolutions of at least 35 thousand per minute at the ground. The downside is that you break one prop each flight. The entire package (model+engine+pipe+prop) is optimised to reach best speed only after extreme dives. No pylon style (no horizontal turns) to be flown but only straight level flights.

Regards

MyWay

Slowmo777. Thanks for your reply. If I have this correct, the plane has about a 186 sq in wing area, a 32 in wing span and weighs about 30 ozs fueled. With a hot 15 racing engine and I'm guessing a 5 or 5.5 pitch prop at 35000 rpm + it will achieve about 200 mph.
Thanks again and btw the name Slowmo is quite fitting. The 777 is ?.

MyWay

I am not getting very many replies so I will throw this at you. Budget speed plane, ie swap meet special. Ouickee 500 kit $40, used os 32 heli engine $35, attack 4 channel radio $40, muffler $5, hardware about $25. Total less than $150. The finished plane with the wings clipped and the tail shortened along with a smaller stab and no landing gear weighed less than 2 1/2 lbs and 360 sq in. Apc 8x8 prop, 20% nitro, and a 3/8 inch hole in muffler outlet = 150mph+.

evan-RCU

I doubt it will go that fast but you told me to limit my input... 130mph is more likely...

MyWay

evan-RCU Thanks for your limited input.

Skull Man

Myway,
The exhaust system is a tuned muffler rather than the full length pipe.[8D].Less weight -n -drag!

The plane is scratch built so the cost is around $25 for the materials.....not including spinner, covering.

270 mah. battery pak, 2 mini servo's, one sub micro (throttle), switch harness. Ready to rock-n-roll

MyWay

Skull Man, Since you had to ask about changing the timing I'm assuming you have never done this before. If thats the case don't. Just enjoy flying the plane as is. Thanks for your input.

Skull Man

Myway,

Never worked an engine....you are correct. I would like to see how it's done. I have the concept of what needs to happen and why. just not familiar with tools required to do the job. I don't want to frigg up a good engine.

Anyway, I hope to learn a little from you guys!

I don't know if it will go faster, but i want it to!...heheheheeeeeeeeeeeee

Here is my favorite!

MyWay

Skull Man, The Jett muffler on a Webra 36 will give you about a 1000 rpm more than you are getting on the OS 32. It has a better match up on the exhaust port and weighs about the same. The other option is to put a tuned pipe on your 32. It will give you another 1000 rpm. In both cases you will be running about 17500+ with an apc 8x8 prop.

Skull Man

O.K. MyWay,

I'll try and tach the rpm's this weekend and see where it is currently running. then we'll try a full length pipe and see the diff.

Can't wait!

slowmo777

Quote:

ORIGINAL: daven (from thread called Nelson .15's )

I saw two Nelson .15's on the auction site today that both looked pretty good. A good place to start on one of those 150 mph speed planes from the other post.


ORIGINAL: HighPlains

Dave, I always liked running my Nelson .15 in QM. Sweet sounds at 25,000 R's with the open mini pipe. I think we were doing about 130 mph with the QM's, so a speed design should be able to 150 with little effort.


ORIGINAL: Ed Smith

I think I said on the "Other post" that the speed claims on this Forum were always good for a laugh. Now, our very own Bob "Boogie Board" Dibble(sp) is in on the act.



ORIGINAL: HighPlains

When things are slow Ed, where else would you look?



ORIGINAL: Ed Smith

I agree Bob, I am glad to see that at last you are starting to understand that British sense of humour.



ORIGINAL: daven

I would think that a more purpose built speed design around a Nelson .15 could push 150 mph. Probably not much more, but definately close.

Hello folks,

you pylon guys probably are right with your statements that a high percentage of the speed claims here in this forum are good for a big laugh.

So is this simple Q justified: "Does this forum deserve the name Extreme Speed Prop Planes?"

However I am convinced that there will be somebody out there in this or in the pylon forum willing to push serious R/C straight line speed in the near future – let’s see. Maybe the moderators as well as performance engine representatives will stimulate this evolution making this forum place #1 for serious straight in line speed?

Please check out my other posts. You need more hints? Well-I don’t think so. It’s winter time guys, right time to design a full fibre glass purpose built high performance speed plane. Makes more fun than just using established or converted F3D-alike pylon designs being less suitable for straight level speed measured within 200 m distance at FAI conditions. And most important is to design the right speed prop. Pylon prop sizes don’t work here!



You want that nasty 200 mph target beat by a hot .15, won’t you?



You want that nasty 250 mph target beat, well which engine size will make it? A .40 F3D, a .60 (will be conform to FAI speed too) or.65 or even a .90 ducted fan engine?



And which prop sizes and prop designs will be the most sophisticated for these speeds?



Does a constant prop pitch have disadvantages?



What about speed props characterised by different airfoils per station?



What is the optimum prop tip design?



How thin can a carbon prop be designed and still being safe during operation?



Are theoretical pitch speed calculations a reliable basis?



Qs like this should be discussed here in the Extreme Speed Prop Planes forum. Besides you pylon guys I believe many others are curious too.




C’mon Ed Smith, HighPlains, daven, Flyboy Dave, bob27s, MyWay...





[][sm=confused.gif]

MyWay

Slowmo777 , Why are you picking on me? I never said 150mph + was next to impossible with small engines. I know better.

Bob.R

My Feedback: (2)

I think it would be fun if one of the german speed guys would do a build thread for an extreme speed plane. Slowmo, ever cross paths with der_steuermann?

Skull Man

Bobber,
sure is a really short prop you have in the photo? heh

seriously, what engine is it?

O.K. Myway,

I believe I'm gonna attempt to change the timing of the .32..... with a little help from one of my motorcycle drag racing buds. He says it's easy and I'll get to see it happen! If I break it, we'll just have to try again! I'll check RPM's before and after

MyWay

Skull Man. If you insist, have your buddy set the top of the exhaust port at .255" above the top of the piston when piston is at bottom dead center. Good luck.