News:




  • September 19, 2017, 01:02:48 PM

Login with username, password and session length

Author Topic: Fora 21  (Read 478 times)

Offline phil c

  • 2015
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1736
Fora 21
« on: September 10, 2017, 04:36:49 PM »
I know some of you have tried the Fora 21 for slow combat, and there have been problems.
My buddy Oleg got a couple the season before last.  They broke in pretty easily, maybe 6-10 runs, starting a bit rich and working the needle in a bit after each flight.
But they never settled down and ran well.  By comparison, the standard Fora 15 would break in in 4-5 flights.  By then it steadied down and started running very reliably and steady while gradually getting faster with each flight.

The 21 never settled down.  We tried different fuels, different size venturis, different props, new bladders, and different needle settings.  He gave up for awhile and switched to a couple LA 25's which broke in and ran fine(Japanese built silver ones).
This summer he brought the Foras out again and still had the same problems.  Out of frustration he swapped the long plugs he'd been using in the LA 25 for an OS A3(a short plug).  Next flight it ran perfectly with the usual slightly rich setting on launch.  It also ran fine on the APS 8/4, the 9/3N, and a few other props.  As a bonus it ran over 6 minutes on barely 3oz. of fuel.

This may not be a cure-all, but it's worth a try.
phil Cartier


Offline Bob Mears

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 162
Re: Fora 21
« Reply #1 on: September 11, 2017, 07:29:15 AM »
Thats good info! I finally gave up on mine and threw it in the engine drawer. Maybe tie to dig it out and give a short p
lug a shot!

Offline phil c

  • 2015
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1736
Re: Fora 21
« Reply #2 on: September 12, 2017, 03:35:59 PM »
It might be something to do with compression.  The exposed threads with a short plug also probably foul up the combustion a little, keeping it from firing as hard.
phil Cartier

Online tim lackey

  • 2017
  • Trade Count: (0)
  • Ensign
  • *
  • Posts: 27
Re: Fora 21
« Reply #3 on: September 13, 2017, 07:50:19 PM »
Thanks for this info. I got one two years ago tried everything
I could think of props, fuel, venturis, plugs nothing worked.
I didn't try a short plug though definitely worth a shot!
Tim

Online Dick Tyndall

  • Trade Count: (0)
  • New Pilot
  • *
  • Posts: 11
Re: Fora 21
« Reply #4 on: September 13, 2017, 10:00:31 PM »
   By going to a short glow plug you are delaying the fuel ignition in the combustion chamber, or retarding the timing, like in an automobile engine. To clean up the combustion chamber you might want to machine a smaller dome in the combustion chamber and make it like a "double bubble" head. With the engines we race in our R/C boats we sometimes advance the combustion timing by pulling the glow plug coil wire out of the plug slightly. You just may find out some interesting information playing around with pulling the wire on the glow plugs, using different heat ranges, etc.

Online Ken Burdick

  • Trade Count: (0)
  • Captain
  • *****
  • Posts: 570
Re: Fora 21
« Reply #5 on: September 14, 2017, 09:14:26 AM »
Both Dick and Phil are correct in my opinion.

This is the first I have seen of this thread and would like to know about the fora .21. Is it a sport engine in their line of high performance engines? In a N.W. proto speed event, I have pushed the LA .25 to many limits and when there, the head with a double bubble really begins to cause problems. A step back to a simple hemi seemed to cure this. I'd like to say I understand combustion and what the true effects are, but mostly it's trial and error.
Who sells the Fora .21? Techno?

Thanks

Ken

Offline Bob Mears

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 162
Re: Fora 21
« Reply #6 on: September 14, 2017, 11:12:02 AM »
I got mine from Yaro. It says its a 75mph engine. Andy got his to work a little better than mine, but still not good enough to depend on in an event.    I did built an exhaust restrictor plate on my 21 so I could slow it down a bit. It was adjustable so I could dial it  the right speed.  The problem is still just holding a setting. Mine and Andys both acted like many of the LA 25's. Run great for two minutes then go lean, or rich, or just quit. Acts like a temperature thing. They started great. Andy Finally ran an F2D prop on his....scary!  We finallyboth just put 8/4's on our F2d ships and called it good.

Online Ken Burdick

  • Trade Count: (0)
  • Captain
  • *****
  • Posts: 570
Re: Fora 21
« Reply #7 on: September 14, 2017, 02:45:32 PM »
for s/l I have always used B grade F2D motors, here that is 80 mph so a 7 x 3 apc works great. Slow down to 75 is a problem but the prop you use would do it. No fuss no bother with the 2D engines. Always work and run well.

Offline jim gilmore

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1089
Re: Fora 21
« Reply #8 on: September 14, 2017, 06:26:13 PM »
What or who is Yaro ?

Online tim lackey

  • 2017
  • Trade Count: (0)
  • Ensign
  • *
  • Posts: 27
Re: Fora 21
« Reply #9 on: September 14, 2017, 07:14:08 PM »
My experience is the same as Bob's. I actually launched for him a few times at brodaks two years back. Mine came with a large Yaro venturi and a small stock one both do the same run great mabe one or two minutes then quit. Very easy to restart no cool down time needed. Going to try per Phil a short plug.

Offline Bob Mears

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 162
Re: Fora 21
« Reply #10 on: September 15, 2017, 07:42:21 AM »

Online Fredvon4

  • 2017
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1131
Re: Fora 21
« Reply #11 on: September 15, 2017, 07:48:11 AM »
Yaro is a guy in Canada that sells a lot of combat stuff mostly Eastern European sorced

http://aerohobby.ca/store/index.php?main_page=index&cPath=1
"A good scare teaches more than good advice"

"Worry is the interest you pay when you borrow trouble"

"The unpunished never learn"

Fred von Gortler IV

Offline kenneth cook

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1015
Re: Fora 21
« Reply #12 on: September 15, 2017, 02:05:16 PM »
               Phil, I remember Oleg flying the Fora when he just received it. I heard it in the background and it was sounding like a F2D engine. I was quite shocked to see it was similar to the LA's that day in terms of speed. I don't recall any issues with the engine runs on that day. Has he been using the Fora on a regular frequency?


Tags: