Twin engine homebuilt....

Check out my JAG-2 homebuilt...

www.homebuiltdirectory.com

Listed under Original "one-off" Designs

Wow, that is innovative to say the least. Nice craftsmanship!
Good luck!

Hey, cool project.

However, I have to wonder: You're doubling the frontal area of the airplane (at least), but only increasing power by ~25%. You're also apparently using fixed-pitch props. What do you estimate the single-engine rate of climb will be?

Out of curiosity, how are you getting one of the Corvairs to turn in the opposite direction (e.g., "counter-rotating carbon fiber props")? Does it take a custom cam, or is there an easier way?

Ron Wanttaja

I will give you credit for being serious about the word experimental! Wow, what are you doing to beef up the wing to account for the engine installations? What about wing area? Will you now be flying under a higher wing loading? What about CG?, without that lycoming out front will you be tail heavy?

Hi Ron (read one of your books...great work) & Todd (and all the other interested parties on the other forums...)

I'm choosing to respond here on the EAA Forums because I feel that they promote experimental homebuilding as a whole vs. for a particular type of homebuilt. Also, I highly respect a lot of posters here (Ron, Chad, etc.) There are a lot of great forums out there but I feel some (most) have their own interests at heart instead of sharing knowledge across the homebuilding community. For example, there's a lot of information that a Sonex builder can share with a RV builder and vice versa. Open up people...for the sake of homebuilding! This is why I decided to build www.homebuiltdirectory.com, so ALL builders can show their craftsmanship to a collective group of homebuilders, or better yet, prospective homebuilders. I would also like to personally THANK everyone who has registered and listed their aircraft. There is some very beautiful aircraft there and reminds me why I build!


Anyway, this will be my one and only post on the forums. I prefer to spend my time IN the hangar. I will list here a lot of answers to the questions I have found on the forums...some of which I feel are elementary and obvious. I am going to list these comments/answers in a list format in no particular order...

1. THIS IS NOT A TWIN RV-6A!!!! It is a JAG-2. Just as the RV-3 is not a Stits Playboy.
2. This one is for all of the "experimenters" who are building match drilled quick build kits with brand new Lycomings & Sensenich props...embroidering "RV" into your leather seats is NOT a major modification! Take it easy now...just kidding.

Why a twin...

1. Regardless of all the ignorant posts regarding twin engine performance...keep in mind the glide ratio of a twin with an engine out is better than that of a single engine aircraft eith an engine out...period.
2. Of my 15,000 flight hours, 14,500 are multi-engine.
3. I don't care for the taste of pine nor am I a good swimmer.

The airframe...

1. 3 years of engineering & due diligence has gone into this project. All necessary structural modifications are being performed.
2. Increasing wing area to compensate for increased gross weight.
3. Increasing tail area for increased wing area and to make Vmc more manageable.
4. Custom made main gear legs.
5. Re-designing the nose gear.
6. CG calculations have been done...no worries.
7. 54 US gallons of fuel in (2) 27 gallon welded aluminum tanks located just aft of their respective firewall.

The engines...

1. The Corvair 2850cc is a very robust smooth running 6 cylinder air-cooled direct drive engine.
2. Many mods will be performed on the engine to adapt to my application.
3. One engine will have a custom cam and other minor mods to reverse rotate it.
4. 5th bearings will be added to the case to increase frontal bearing area similar to an O-200.
5. The Corvair 2850cc puts out an honest 110hp (proven & tested). The Lycoming O-320 is rated at 160hp (they had to market these things!!!) but I bet only puts out 80-90% of that on a dyno.

The props...

Nothing to discuss here other than they will be 66" 3-blade counter-rotating and very lightweight. There will be a unique prop brake system installed which will stop a windmilling prop.

The performance...

1. Estimated empty weight...1450lbs
2. Gross weight...2200lbs
3. Estimated cruise...180-200mph
4. Estimated 2 engine climb rate...1500fpm (will hold altitude to approximately 5000' with engine out...flight testing will determine)
5. Endurance...4 hours

I feel my performance goals are realistic through testing, calculations & comparables. Keep in mind the JAG-2 will have a drag profile 125% of the Wing Derringer but at 60% the weights of a WD. The WD originally flew with O-200's but couldn't meet performance goals at the heavier weights. The engines were upgraded to O-320's and obtained decent climb and a cruise speed of over 210mph. The dimensions of the two aircraft are almost identical.

There are hundreds of other mods but I just don't have the time to discuss. All future updates & photos will be posted at www.homebuiltdirectory.com.

Will the last REAL experimental aircraft builder please shutoff the lights on the way out...


Best regards,

Jim Tomaszewski
EAA# 590427

Good work Jim. I will follow your progress, espescialy when you move on to the prop brake. I heard long ago that a stopped prop is almost as effective as a feathered one. However, I don't think any plane has ever used it. Mechanical or hydraulic?
Bob

I like it and the concept. But don't make this your only post, give us an update next summer or whenever you hit a good milestone. Brian

This is great stuff Jim...and I have to agree with Brian and invite you to post often with updates. Contrary to many naysayers that have posted on other forums about your project, none of whom know your background and what has gone in to this project, there are PLENTY of us out there that see this project as something to watch with big interest, and we want to see your success and celebrate with you.

Keep the info and pics coming!

:cool:

Thanks guys...

I will find the time to keep you posted. Once again, it's the sharing of information amongst the "cliques" of homebuilders is what is important.

The prop brake system I'll be using will be mechanical. My motto is..."Simplicity with redundency gives you reliability".

I'll stay in touch.

Jim
www.homebuiltdirectory.com

hooray. way to go Jim. Can't wait to see the finished Jag-2

There was/is a simmilar aerobatic light twin developed in the UK. There is a thread discussing it on Pprune ( Proffesional pilots rumour network) It was tandem seating with two 0-200s. I think they are developing another with larger engines.
http://www.pprune.org/private-flying...speedtwin.html
and http://www.glue-it.co.uk/aircraft/ph...e2e/index.html

I am working on a twin design. What I am trying to determine is the right size engine. Is there any formula(e) for this?

I am hoping that a compression ignition engine will be available by the time I get done.

I recently posted an update of my project at www.homebuiltdirectory.com. It is listed under "original one-off designs" and is named the TWIN JAG. I also recently posted a story with pictures on www.flycorvair.net. I'm actually a little further ahead than the pictures I just posted. Rather spend my time building and less time talking...lol.

Hoping to finish and fly the TWIN JAG out to Airventure 2014!