Here are a few new photos of my twin engine project. More to come shortly at www.homebuiltdirectory.com.
Here are a few new photos of my twin engine project. More to come shortly at www.homebuiltdirectory.com.
Last edited by jimdc8; 08-24-2013 at 08:29 PM.
Newest photo as of today (bottom photo)! Engines being built shortly.
Last edited by jimdc8; 08-24-2013 at 08:26 PM.
That is a very interesting project! I have been toying with the idea of designing a light twin for some time now, given the rapidity with which engines are growing more efficient, airframes are getting lighter and stronger, etc...
Looks like you've adapted an RV-7 or something(?)
Would love to see more photos! Keep up the good work. Can't wait to see that fly!
Thank you for the kind words! I will be adding more pictures very shortly. I am currently finishing the instrument panel/center console installation, minus avionics for now. Used to be a RV-6A. Now it is called a Twin JAG.
More coming soon.
Jim
Here are some more recent photos. Trial fitting the burlwood panels on the center console. More pics coming soon...
What engines are you planning on using?
-Jim
I am building custom 120hp Corvair based flight engines. They are direct drive 6 cylinder air cooled and are very smooth running engines. They contain a fifth bearing to handle loads imposed on the crankshaft by the props. My engines will use the following brand new custom parts:
1. 4340 billet ion-nitrided crankshafts
2. Custom pistons & cylinders
3. 4340 connecting rods
4. Falcon machine heads
5. High volume oil pumps
6. Weseman 5th Bearing
7. ...much more!
I will begin building these engines in the next few weeks.
Jim
Last edited by jimdc8; 12-25-2013 at 08:44 PM.
Measure it with a micrometer, mark it with a grease pencil & cut it with an axe.
Very nice project!
.
Your Dec 17 post included a picture of your console with the #1 & #2 PROP BRAKE controls. I had only seen passing reference to brakes in obscure texts. A recent forum thread regarding the Bally B-17 replica had pictures of those powerplants and some folks thought the brake drum looking things aft of the props were freewheeling devices. There were some opinions expressed that a free wheeling prop on a shut down engine was desirable.
Could you bring us up to speed regarding the relative drag of a feathered prop vs a braked prop vs a free wheeling prop. I can't wait to see pictures of your brake system. It could turn out to be lighter than a cs feathering prop. As if there were one even available for a 120 hp Corvair. Can't go wrong with the Corvairs.
Bob
Thanks Bob!
As you know, a constant speed prop is both heavy and complex. It is also a failure point and it's weight puts stress on the crankshaft. My concept of a prop brake is a simple one...I will install a mechanical brake caliper, identical to a bicycle's, which will stop the windmilling prop using the machined surface of the flywheel (just under the teeth where the starter meshes with).
Here are a few of my thoughts for this setup:
1. A feathered prop, using a constant speed prop, effectively reduces drag approximately 97% compared to an unfeathered windmilling prop.
2. A stopped unfeathered prop, using my proposed braking system, effectively reduces drag approximately 93% compared to an unfeathered windmilling prop.
3. I feel that with a simpler and lighter setup, I would be willing to live with the 4% degradation in performance. I can makeup the difference by setting limitations to the operation of the aircraft (ie. minimum runway lengths).
These are just some generic thoughts of mine that describes why I am choosing this route. It is much more in depth than I can describe on this forum. Hope this helps.
Jim
Measure it with a micrometer, mark it with a grease pencil & cut it with an axe.