Thank you Robbie

First I,d like to say I am no expert in aerodynamics, building or flying but have dabbled with multi's quite a bit with many of them being bashed singles and have accumulated a large number of flights among them.

duelest, K & B .48's

A bashed no name 40 size trainer, K & B .20's in bathtub nacelles

Another bashed no name trainer into a twin boom push pull twin, K&B .40's

Royal P-38, piped OS .61FX's. This one intended for the old SWRA warbird pylon races before the SWRA's demise

Keosho ARF F-82, piped OS .61FX's also for the Swra events

On the table:

Uc-78 Bamboo Bomber with .20/.25's undetermined yet and retracts for controlline. Primarily as a test bed to fully utilize my 'Bill Young' three channel electronic (over the wire) Ukie system.

Last and my favorite a Senior Kadet bashed with four bathtubs for four .15/.20's


The push/pull twin has been a no brainer of course and just flys like a heavy trainer. The only differance between it and a single is the fact that during a single engine takeoff on the rear engine you experiance a right yaw at rotation instead of left due to 'P' factor.

The best one of the bunch has been the conventionally bashed trainer with the twentys. Several hundred flights, nice basic aerobatics and great single engine performance that includes single engine takeoffs with the 'critical' left side shut down. More on why in a bit. This ship has been well received at several full scale airshows.

The two pylon ships, F-82 and the P-38 were failures for their intended purpose. Both were over powered which made the P-38 quite heavy at close to 15 lbs with something just over 700 squares that put the load at over 40 ounces per square. In the 10 or 12 flights it flew delightfully and was fast but during practice on the course I pulled a bit to much 'G' and she double snapped from thirty feet into the ground just like a lightening strike (pun intended), It will live agine eventually but with smaller engines and not as a racer. The F-82 with quite a few more squares to lighten the load also before reaching a race experianced an outer wing joint failure and is total history.

There are two points I would like to share surmised from my dabbling, the first is when selecting power for a twin particularly a bashed twin you will experiance a performance improvement from the fact that when adding an engine even if it is similar total power as a pair to what originally was about the same power as a single. This improvement is a result of reducing the propellor disc loading by close to half and manifests itself in low speed thrust i.e. climb, takeoff and vertical not in speed. Kinda like a large fine pitch prop as opposed to a short course one for speed.

The next point and most important is out thrust on both sides. this one is vital to a multis long life. This is the one factor that makes the little bashed trainer so successful and able to perform single engine takeoffs. It does drastically reduce the rudder work load when you loose one and you will. I just don,t understand why most model designers don,t use it or some odd combination some on one side and not the other. If you research it I think you will find most full scale light twins do use considerable out thrust on both sides.

The Quad Kadet which is going slowly due to my medical condition will have bathtub nacelles that are hinged and wing nutted to adjust outboard up to six degrees and the plan is to use about half the out thrust on the inboards as the outboards.

With the exception of the electronic controls for the controlline twin I have not done anything exotic with tank setups using just individual tanks or electronic yaw control and synchronizers. Not at all aginst it, just like to keep it simple, the rudder gyro is probably a very good idea. A synchroizer may be a good idea on the giant ships, particularly if they may be overpowered ones but on the mid sized airplanes its probably overkill as a slight mismatch does not seem to be a problem and would be even less a problem with a rudder gyro. Here's a thought that distinctive non-synchronus throb is always an attention getter for your audience anyway.

Thank you for allowing me to share and looking forward to your experiances with the electronic apurtenances.


John