P-38 power

[RiBell]

Thinking about doing a Guillows P-38.
As for power I've got a Norvel 0.061 and an OS-10.
If going to the effort of adding retracts, and maybe flaps.
One of these engines would need a mate on the other boom.
Any thoughts as to which one would be a better choice

[Lynn S]

The O.S. may be easier to work with. Twin engine planes are really hard to fly if you have one engine out. Years ago I saw a nice P38 with two .60 engines go out of control when one engine died.:(

[T. Lyttle]

Years ago, there was an article on that conversion, using a TD049 and the "mini radio" of the era (Cannon TiniBrick!); flew fine. I built one off the Guillow plan, much simplified, ran a pair of Babe Bees and standard radio gear: frightening! Personally, I see no reason to overpower that model, particularly if you are sticking to much of the original structure. My BB powered model was fine if an engine quit, just keep the speed up is all, but I had ~3deg offset on both engines, plus a couple deg DOWNthrust on the RIGHT engine. Lost the model in moving, not to catastrophe.

[easytiger]

Definitely the Norvels. The OS 10 is a HUGE step up in weight and bulk. It's just too big! See my thread on the A-20 for a similar project.
Forget retracts and flaps, you will just be building a brick. Think light. Think light. Think light.
Don't worry about power...twins have built in advantages...those two 061s will not be like an .12, but more like a 20, because of the additional prop area and efficiency.

[T. Lyttle]

Exactly. Think light, build light (not fragile, there is a difference), skip ANYTHING that the model doesn't really need. While my P38 was an experiment, it proved a lot to me, ie, throttles are less necessary than 2 engines matched in power and run time. Sure, once launched, I had no choice about whether to continue or not, but I was there to learn. 1/2As (particularly the Norvels) develop enough power to fly that model one at a time, never mnd in pairs!

[RiBell]

I'm just hoping that I can get a Norvel that is the same as the one that I've already got.
If I skip the throttle I could always use the TD.049's I've got two of those.
Rick

[easytiger]

The problem with skipping the throttles is it is very difficult to get both engines to stop at the same time. Guess how I found this out!

[RiBell]

Yeah, Ya really need throtles.
That's one that I've thought about, I was even trying to figure if the firewalls could somehow be made floating, so that the rudder would kick over when one engine quit.
Then remembered the K.I.S.S. principle.
I think that the Norvels would be the way to go. Just need to figure out if the one that I have is still available in order to match it up.
Rick

[T. Lyttle]

I ain't so sure about throttles. Like I said, if you work the thrust liines properly engine out is an inconvenience, but not the end of the project! Mine had ~3deg outthrust on each side, plus 2deg down on the Right engine only. The only indicators of an engine out was no climb, and a yaw towards the out engine, both easily accommodated. I built mine simple (ie, expendable) just so I could find out first-hand about this; with the Babe Bees, it was easy to match fuel runs fairly closely, but on one flight I had a failure 30sec after takeoff, and, while the flight was boring (no climb) is was very manageable.

I tried to find the article on the r/c conversion; too much chaos. I think it was Don Srull's project using ONE TD on a fairly stock build, ie, no gear or throttle. If I find the article I will relay the results... A TD or a Norvel has LOTS of power, guys...

[RiBell]

T.Lyttle.
You figure that done as a 2ch then with just ailerons and elevator, and a pair of Cox TD049's would be the way to go then?

[T. Lyttle]

Like I said, mine was simpler (not lighter) than the kit, and the reeds flew it REALLY well; my buddy will attest to that! A pair of Gold Bees would give you a very satisfying flight, and start much easier than TDs.

The Norvels are more than plenty (apparently, never owned one, no glo fuel for 80 miles), and if they are as light as reported WITH throttles, the extra servo won't change much except the flexibility of its flight pattern. But buld light, build strong; these two are not incompatible.

[RiBell]

Just that I've got a pair of TD's and one Norvel.
Oh well got other projects to finish first.
Rick

[T. Lyttle]

Naaah, don't quit yet, use the TDs if you got'em but I suggest you build just that bit stronger; those beasts pull, particularly in pairs. Also like I said, the norvel in the nose will pull that model just fine; just don't expect out-of-sight vertical rolls is all! Otherwise, I would still expect a very flyable model.