Variable Pitch Propellors for Indoor Free Flight 

I'm working toward some build videos on these but bear in mind that they are very intricate and fragile.

The best I can do to help is to direct you to indoornewsandviews.com/downloads/ and this book: www.indoormodelairplanes.com/

Unless you've heard differently, Ron is still around. I've heard from him as recently as last year. Great guy working to grow indoor. :)

@@joshuawfinn @joshuawfinn ok thats good to hear. I thought I heard unfortunate news. But I'm happy to be informed hes still around. Thanks for your response! Ive been in the hospital for the last 3 weeks due to a hit and run accident. Best news I've had since. Its good to see someone keeping this hobby alive! Your variable pitch prop is amazing i wish I had a place to fly these indoor works of art.

Which airplane are you trying to fly?

jhaerospace.com/

Possible, yes, but quite inefficient. The goal of variable pitch is to transfer all the energy into the air as thrust, just in a delayed fashion. Friction just burns the energy off as heat.

I don't use twitter, but you can email me through the contact form at jhaerospace.com

Ken Wiberg indeed! Future video topic for sure.

jhaerospace.com/

Rolando Torrico two loops of 1/8" Tan Supersport from faimodelsupply.com will fly that airplane nicely.

Unfortunately I don't know of anything in Spanish. That said, if you go to indoornewsandviews.com and look at the Downloads section, you'll find many volumes of detailed information. Especially "The Best of INAV".

@@joshuawfinn gracias

I don't know any languages except English, I'm sorry.

At this point, high end Lipo technology is the best energy source you can get for small models. For larger stuff, the ultimate energy density sources remain diesel/kerosene type fuels. I think the ultimate indoor endurance record for electric R/C is around 6 hours, as opposed to 1 hour for rubber power.

Aditya Mahajan, until you're competing at a really high level, Tan Supersport from faimodelsupply.com will do everything you need and more. If you don't have a rubber stripper, order presized rubber from freedomflightmodels.com or Retro RC in their Scholastic section.

you can shoot me an email through the contact form at jhaerospace.com

A 3 percent arc airfoil is a circular arc subtended by a chord such that the maximum separation of the arc from the chord is 3 percent of the chord length. Given the chord length c and the maximum height h of the arc, we need to know the radius r of the circle. The radius is (c squared divided by 8h) plus h/2. You strike and arc of radius r from each end of the chord, the center of the circle is where two arcs intersect, you draw an arc from that center through the ends of the chord and that is your arc airfoil. There is also a simple geometrical construction. Draw the chord line. Draw the point of maximum camber 3% (or whatever you want) of the chord length above the center of the chord. Draw the bisectors of each of the line segments formed by this maximum point and each end point. Where those bisectors intersect is the center of the arc sought. Construct the bisectors by striking arcs of equal radius from each end of the line segment, the radius being somewhat longer than the line segment. The two points of intersection of these arcs determine the bisector line.

It's all a matter prop propeller size to supplied torque at a given airspeed. F1D's and Mulvihills run similar sized propellers in that they move a similar amount of air for a given revolution. The difference is that the Mulvihill is running about 150 times the torque of the F1D, and so the prop runs about 10x faster (there's some quadratic math in there).

Very carefully. ;)We sell them at jhaerospace.com

Mark Bennett, I get polymicro from indoorspecialties.com, but this model is covered in OS Film from hobbyspecialties.com

My website is devoted to providing those kits and parts. Additionally indoorffsupply.com has taken over production and marketing of the materials and tools previously available from Indoor Model Supply like precision cut wood, bearings, rubber and balsa strippers, etc.

@@joshuawfinn Thank you very much. This really is an amazing hobby and am looking forward to getting back into it.

F1D isn't something to start out with. The techniques are pretty extreme. You'll want to get your feet wet with something simple like the kits are lasercutplanes.com, finishing with their Cents of Time pennyplane. Then start building from scratch using the information in 'The Best of INAV' at indoornewsandviews.com and then take a look at thef1dblog.wordpress.com where there is a complete tutorial on building an F1D.

Oh! Thankyou I'm not a absolutely beginner in RC Modeling (I've a EasyGlider from Multiplex) but I've no idea about F1D. The Mountail Lion looks fine but... is too fast. I'll buy it. Talking about other models... they have an special curve in their ribs (naca or similar) or only circular curve? Do you know a easy model (but more difficult and slower than Mountain Lion MK in INAV ??

+itubal I'd recommend looking through "The Best of INAV" and find the information on pennyplanes. Any one of the limited pennyplane plans in there will work. The Banks LPP in issue 137 is as good as any out there.

Oh! Thankyou very very much! This model looks very fine. I like it!!

Класно летает !!!

Awesome! Glad to see another practitioner of our crazy hobby!

+joshuawfinn thanks keep up the great work!

@@joshuawfinn jajaja como lo hizo

Very big, efficient propeller turned buy a very thin rubber motor on a lightweight airplane that requires very little thrust to stay airborne.

@@joshuawfinn wow its trully amazing.. by the way i'm dheperson and i always watching your video you are one of my idol..number 1 fan here in the philippines.thankyou

@@joshuawfinn good day.. i making indoorplane but i dn't know where's cg? Can you pls give me some advice technique theory or idea how to get the cg and my airplane will fly nice and cool like you did.thankyou

The prop certainly is balanced ! the model is moving /swaying because of the torque reaction on the very light airframe,what a work of art this is.

Big, efficient propeller on a super light airplane driven by relatively low torque.

You have to build them. I'm hoping to release a kit eventually, but at the moment that is not an option. Learn more about building them in the downloads section at indoornewandviews.com. Also look at the Senior Flyer build videos we released this week.

@@joshuawfinn thanks!

Yes, but you don't want static thrust, so the rig needs to be moving. The best way to do this is to build a "whirling arm" device which uses a drag plate to simulate the aerodynamic drag of the aircraft. You then measure thrust based on the number of revolutions the arm makes in a given period of time and use the turns and torque at the beginning and end of the test to determine the energy used to generate that thrust for the period of the test.

Is there any instrument on sell that specifically used to measure the thrust?

I don't know of anything commercially available that would provide even remotely usable data.

Thanks, Joshua!

I would think if you had a push prop you could stand it on it's nose running on a digital scale , then just cancel out the weight and have your thrust measurement. if this theory works then you'd have to make a special rig to test prop and motor combos , but I'm pretty sure this would only give an idea of thrust and not an actual measurement.

Right now this is a scratch built-only airplane. Start your research at indoornewsandviews.com

here is the use of rubber band if no so how you fly this plane please give me some trips so that i can also make this plane

Ayaz Ahmad, please contact me through the J&H Aerospace website and we'll work on getting you started. You don't want to begin with F1D. It is extremely different and used highly specialized materials. I'll send you some information on Pennyplane designs and you can get started on those and work your way up to your goal of an F1D.

thanks! You should be able to find a club that does indoor in SoCal. At minimum there is a group up in San Diego, but I'm pretty sure there is one in LA as well. I'd recommend looking through the club directory at freeflight.org and call up one of those groups to see what they know.