News:



  • March 28, 2024, 10:37:29 AM

Login with username, password and session length

Author Topic: blank  (Read 4035 times)

Offline Motorman

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3243
blank
« on: March 12, 2017, 12:09:40 PM »
blank
« Last Edit: March 06, 2022, 09:08:18 AM by Motorman »

Offline paw080

  • Trade Count: (0)
  • Lieutenant
  • ***
  • Posts: 117
Re: .049 for Stunt
« Reply #1 on: March 12, 2017, 01:39:49 PM »
What's a good .049 for stunt? I've got Fox FAI, Cox TD, Cox Medallion, CS, Picco PZero with Gifford crank and Cox Black Widow.

Thanks,
MM 

Hi MM, of the engines you've listed; the Cox Medallion is the best choice. It produces the right amount

of torque in the right RPM range.  The only engine that is better for 1/2A stunt; and when I say 1/2A,

 I mean engines up to .504 cu"; is the PAW .049sbr or tbr diesel engine.  Sorry folks, a 1.0cc or .061cu"

engine is not a half A engine!  Look in your AMA rule book for engine classes.  :o

The Cox .049cu" Medallion will fly a Pinto beautifully.  Barry Baxter used a .049 Medallion in his

230 sq" 1/2A Stuka design.   The Paw .049sbr or tbr diesel can fly a stunt model up to 250 sq"s.

I use PAW .049's  because of the perfect torque/RPM ratio and the Paw requires less than half the

fuel amount compared to a glow engine.  Good luck with whatever you choose to use.    H^^

Tony  ;D

Offline Motorman

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3243
Re: .049 for Stunt
« Reply #2 on: March 12, 2017, 02:32:14 PM »
blank
« Last Edit: March 06, 2022, 09:07:51 AM by Motorman »

Offline Ken Burdick

  • Trade Count: (0)
  • Captain
  • *****
  • Posts: 600
Re: .049 for Stunt
« Reply #3 on: March 12, 2017, 02:40:46 PM »
There is a guy in Oregon who was a fanatic over flying 1/2A stunt. He would go to extremes to built a very light ship which at the times, (1980's) the most powerful Tee Dee he could build. High nitro and all in the name of power. He flew them on ,,,,not sure but thing over 50 ft lines in PA. The airplane was named The "Ridiculous" and it flew so very well. My point being that what engine gives you the most power per ounce is the right choice.

K

Offline RknRusty

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2689
    • My Tube channel
Re: .049 for Stunt
« Reply #4 on: March 12, 2017, 05:22:43 PM »
Would a Cox TD with medallion venturi work the same? I think the medallion has the smaller transfers right? Are you using the 1702 or the low compression head?

Thanks,
MM
Yep, it should. That would solve the TD's problem of drawing fuel on suction.

Cox International will sell you it's version of a TD P/C and they work as well as the old #4 that was on the original engines. The Merlin clamp ring heads and drop-in plugs work great too, but they are too high compression unless you use extra copper head gaskets, usually 3-5 of them hits the sweet spot. It's about the same as the Norvel 1/2A head/plug. Cox Int. sells them too. So does Brodak and others.
Rusty

EDIT: I wrote this ignoring the object of the question was for a stunt run. The Medallion is tamer with the porting and crankshaft intake timing. The guys below set that straight.
« Last Edit: March 13, 2017, 08:30:59 PM by RknRusty »
DON'T PANIC!
Rusty Knowlton
... and never Ever think about how good you are at something...
while you're doing it!

Jackson Flyers Association (a.k.a. The Wildcat Rangers(C/L))- Fort Jackson, SC
Metrolina Control Line Society (MCLS) - Huntersville, NC - The Carolina Gang
Congaree Flyers - Gaston, SC -  http://www.congareeflyer.com
www.coxengineforum.com

Offline paw080

  • Trade Count: (0)
  • Lieutenant
  • ***
  • Posts: 117
Re: .049 for Stunt
« Reply #5 on: March 13, 2017, 11:27:27 AM »
Would a Cox TD with medallion venturi work the same? I think the medallion has the smaller transfers right? Are you using the 1702 or the low compression head?

Thanks,
MM

Hi MM, Nope! The problem with using a TD is what I said in my prior response;

the TD makes max power in the wrong RPM range for Stunt flying. The TD was a great

engine in it's day for Speed, Combat, and Free Flight; or even for fun sport flying.

Changing the venturi will not change the max torque range at all; it also may not

slow the TD down much either. For example I used the stock TD venturi id for

my 1/2A combat models and for a 1/2A speed ship. My 1/2A Combat models

flew between 71-74 mph, depending on particular props used, and my

1/2A speed ship went over 103 mph with a well fit TD engine. all this was with

good old Cox 30% nitro fuel.  Again best of luck;

Tony

 

Offline Fredvon4

  • 23 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2099
  • Central Texas
Re: .049 for Stunt
« Reply #6 on: March 13, 2017, 01:27:44 PM »
My Sig Sky Ray has Black Widow and is a pain to get a good full tank run....and I know what I am doing with Tanked Reed engines..

All my combat planes use NV, Fora, Pico, TeeDee power--- all on bladder

All my 1/2a balsa stunt planes; Black Hawk PT 19, Baby Clown, Lil Jumpin Bean, and Baby Ring master Bi-Plane are powered by Cox .049 Medallions and balloon tank

The Medallion has several reasons for being a good choice...
1. Easy starting on a standard or balloon tank
2. Run time easy adjusted by tank size
3. More power than any of the typical reed engines
4. Beam OR radial mount ( with a Texas Timers screw in back-plate)
5. Likes anything from 15% to 35% N
6. Wide range of usable propellers
7. Can be made a tad hotter with a .051 P/C set
8. Galbraith and others make a good head that adds power if needed ( I run Galbraith heads and Nelson Plugs)
9. Also uses (as I do) the currently available TeeDee P/C assy from Cox International

NOTE...The Medallion Crank inlet is round hole Vs the TeeDee square inlet and has a slightly different timing...So just putting a Medallion Venturi plastic part does not really Tame the TeeDee

Note2 ...Do use a very good polish of the Medallion crank nose bearing areas...this adds a noticeably fair amount of RPM

Note3...Follow Paul Gibeault's Mouse Race engine hints of P/C fit
"A good scare teaches more than good advice"

Fred von Gortler IV

Offline Larry Renger

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 3995
Re: .049 for Stunt
« Reply #7 on: March 13, 2017, 01:37:31 PM »
All excellent advice, I couldn't have said it better!  H^^
Think S.M.A.L.L. y'all and, it's all good, CL, FF and RC!

DesignMan
 BTW, Dracula Sucks!  A closed mouth gathers no feet!

Offline Skip Chernoff

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1445
Re: .049 for Stunt
« Reply #8 on: March 13, 2017, 09:30:24 PM »
I decided not to use my trust TD 051 in my new Pinto and opted for my G Mark .061 .....Why? Because the G Mark seems to have a very flat torque curve and is not sensitive to needle valve settings. The fuel draw was great running on suction with an ancient 3/4oz Perfect wedge tank. I ran it on homebrew 25% .If you can get your hands on one of these engines you would not be disappointed....PhillySkip

Online ray copeland

  • 24 supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 871
Re: .049 for Stunt
« Reply #9 on: March 13, 2017, 09:47:23 PM »
Skip, what is a G Mark?
Ray from Greensboro, North Carolina , six laps inverted so far with my hand held vertically!!! (forgot to mention, none level!) AMA# 902150

Offline Larry Renger

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 3995
Re: .049 for Stunt
« Reply #10 on: March 14, 2017, 09:27:47 AM »
When did you get a G-mark? By now that is a pretty rare beastie!
Think S.M.A.L.L. y'all and, it's all good, CL, FF and RC!

DesignMan
 BTW, Dracula Sucks!  A closed mouth gathers no feet!

Offline kenneth cook

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1464
Re: .049 for Stunt
« Reply #11 on: March 18, 2017, 01:32:58 PM »
             I know MM didn't ask for a particular engine but rather a choice of what he offered, Larry has had very good success using the AP Wasp .061. I'm also well aware that the .061 isn't true 1/2A but many allowances have been made for situations like this. It rendered my true .049 bushed engines obsolete in 1/2A combat. For stunt though, it really has benefits knowing you have a little extra grunt if you need it. The AP can still be found but not as readily as it once was. I tried it in 1/2A combat and I had a major problem with the shaft wearing out the bushing in the case. In addition, the engine kept blowing plugs which sidelined the engine due to the fact I spent more on plugs than the entire engine. Seeing MM's posts, he likes a bit of tinkering and machining which I enjoy myself. I had my flying friend machine a aluminum adapter to the AP case with the 1/4-32 threads internally which allows a Cox TD needle valve assembly to be screwed into it. I want to explore this avenue myself again but rather use it for stunt vs combat. I was using a small prop and really running the engine over it's prescribed rpm parameters. I think this engine would be a neat little project as I know Larry talked about this engine for a good bit of time. Remember, the AP was the only engine available for quite a spurt. Jan Holuszko made the venturi assembly for the AP .061. Sadly these are no longer offered. However, if tinkering is in the plan, a simple adapter which uses the TD assembly works equally as well. I used wheel collar screws to hold the venturi in place by just tapping the existing holes in the case. My setup used to be on the sticky bulletin board but I no longer can find it, maybe a search on here can dig it out of the archives. Anyway, I think it could be a very inexpensive alternative which could be real fun. Ken

Offline Paul Smith

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 5793
Re: .049 for Stunt
« Reply #12 on: March 19, 2017, 08:58:54 AM »
I've run Medallion front ends on TD's with no problem.

I've also downsided TD venturis with good success.  Fill the spray holes with greased pins, then epoxy it shut.  Withdraw the pins and redrill to a smaller size.

The proper RPM for any event is the RPM the engine wants.

If I had need for another 1/2A stunter I'd make a 4' model with a Ukrainian combat engine.
Paul Smith


Advertise Here
Tags:
 


Advertise Here