colmo-RCU

I built the conversion for the .40 supersportster out of RCM plans, and managed to finish it 12 oz. under the design weight. I fit 2 gms 32's which ran great on the bench, but gave me hell on the field. At last I set the carbs in the normal front position (they were on the back originally), but nevertheless 1 or the other quit in flight.

First, I found that no matter how fast I was going, the plane will instantly snap when an engine quits. Also I found (the hard way, off course) that a twin snapping to the ground will be much harder to recover because of the momentum of all the weight of the engines and fuel tanks, which tend to keep rolling a lot more than a single.

Obviously, this is my first twin, it has about 1 deg out thrust on both and I would love to be able to fly it well. Maybe I'll just get good engines next time.


Any comments??? THX

Colmo



PS pics are comming soon

adrenalnjunky

My Feedback: (18)

hobbypeople.net is closing out the Magnum .32's for $49 each - I have one on a profile and it swings a 10x4 APC 2 blade nicely. It's been very reliable, dozens of flights with no deadsticks.

Price is hard to beat.

gsmith6879

My Feedback: (37)

I am using GMS .76 engines on my 80" OV10 Bronco. I lost the airplane on take off when one engine quit. After the rebuild, I took one of the club member's advise and added full time on board glow to both engines and have had no problems since.

BillS

Sorry to hear about the airplane snapping on engine out.

The hardest thing in the world to teach yourself is to treat an engine out as a dead stick. It also requires no other airplanes in the air so you can hear the engines. Seems the natural tendency for everyone is to attempt to fly out of an engine out condition. Power is your enemy. My experience indicates that learning to dead stick on engine out is the first protection. For me the second protection has been to practice simulated engine out at altitude. The radio is programmed to reduce throttle on right or left engine to a fixed value. Practicing emergency conditions in non-emergency time has been critical to my learning process.

Bill

I should have added that vibration harmonics are often terrible on twins. Foam and tank arrangements that might fly for years in a single will often vibrate vigorously enough to put air bubbles in a fuel line. And then the bubble will shut down an engine. Unfortunately foaming fuel and bubbles are most difficult to find and identify. I have simply accepted that occasionally an engine will shut down and engine out simulation experience in non-emergency time is mandatory. There simply is not time to learn after the event happens. After landing after my last engine shutdown it was discovered that the experienced fliers had fully expected to observe the crash. They actually seemed surprised that a landing was made with the other engine running. I was happy to disappoint them.

By the way I have never run glow heat on anything.

Twinman’s trick of having a buddy stand beside you and move rudder trim to max in one direction is also a method of gaining a feel of what an engine out will be like. Most have had difficulty before three circuits are completed.

While practicing simulated outs on my airplane a buddy declared the throttle to be useless. He would fly and I would throw the engine out switch. When he became confused the switch would be thrown in the other direction returning both engines to the same speed. The comment was interesting and indicated that throttling up was a definite mistake.

TAZ

I to have see a twin die when one of it's engines cut but when rebuilt alan the pilot took the idea of fitting a D cell ni-cad for each engine so that it glows during the entire flight, It also makes needing a glow stick pretty much redundant all you have to do is flick a switch on the plane and the plugs start to glow. You will get about 5 or 6 flight per battery

captjack

My Feedback: (3)

One thing i would add is if you are using 32's on a 40 size plane you may have overpowered it for one engine flight.you may be better off with .20's.back in 73 i had a twin that used st 15's fine when both were running but when one died even tho i had plenty of airspeed,with the one engine at idle as soon as i tried flair for landing it would try to snap.replaced the 15 with os 10 fsr and what a difference .loose an engine plane starts snap rolling cut power,snaproll stops and just fly it down with out a problem.still have it in flying condition after all these years.

twinman

My Feedback: (2)

Hi Colmo,
Sorry about the plane. I am not familar with this plane, so I can only off a few suggestions. Do you ALWAYS fly with coordinated rudder and aileron. If not, learn now. Engine out is not the time to learn. Does the plane have a large rudder? If not, increase the cross section. This increases control and reduces the snap roll. Did the plane snap in level flight or upon power up? It should yaw a bit, but unless it is a P-38, usually they do not snap instantly in lever flight. Always do the vertical test. Using a buddy, hold the plane straight up and power up to full power for up to 10 seconds. ANY change in rpm is dangerous. Always run richer than you would on a single for added insurance. Never take off at a high climb rate. Now before any of my "Buddies" start complaining, about what I do or don't do, make take off rolls long and fast with a gentle climb out. Engine out on take off is VERY difficult to recover from for anyone.
Don't give up and keep us posted.
Twinman