The O.F.F.C. meeting this morning was practice for next week's RTP speed contest.  The pylon was at one end of the gym to keep the center clear for free flight models. 

I was trying various combinations of props and rubber to see if I could get one of my speed models over 30 mph.  The Speed Merchant did 29 and a fraction at the contest three years ago on four strands of ancient Pirelli rubber.  I still had enough left to make one more motor but, as might have been expected, the Pirelli disintegrated as I tried to wind it. Well, that's history.

I couldn't get my "open" class model over 15 mph on four strands of 1/8" F.A.I, tan and the Speed Merchant ("closed class") would only go a bit over 20 mph so I decided to try six stand motors.  I made up a six strand motor, lubed it well, stuffed it into the Speed Merchant and cranked 600 turns into it.  It only takes three laps to get a timing so these motors are quite short and 600 turns had frightening torque.

Normally, these models only rise as high as the top of the pylon since they are set up with no incidence or decalage and have ventral fins to hold them level at take off.  This time the model jumped into the air and leveled out at basket ball hoop level which was when we found that there was no gap between the limit of the tether and the basket ball hoop at that end of the gym.  The speed merchant hit the metal hoop at about 30 mph and shattered.  Needless to say, the pylon will be moved over a bit next week!  Now I have to build a new one...

The photo of the models on the floor shows three "open" class models and a profile racer class model.  The one with the butterfly tail is Jim Leuken's 30+ mph "open" winner from three years ago.

That looks cool
Paul

Now, all I had to do was key the tail cone, run a prop shaft through it as a rear hook, and I had a fuselage.

Finally, I got to work on my model, the Speed Merchant.

I decided to go with the rolled tube version since Bill Watson gifted me with a rolled tube he made for his model that apparently did not meet his specs.  I found it to be a very nice tube.  He made it the way I do by rolling the wet balsa and a layer of wet silkspan around a mandrel.  He lets his dry overnight.  The silkspan drys first and wicks the moisture out of the balsa.  I'm not that patient so I bake them in the oven.  Since my wife is not retired and I am a house husband I can get away with it.

Now to make the nose cone and tail cone.  As it turned out I had the nose cone already made, I found it in my junk box.  It was the nose cone from my "Unintended" P30 that was destroyed in the opossum invasion last year.  It was for the same diameter rolled tube fuselage.  All I had to do was replace the prop with the aggressive Ikara prop that I have been testing and install a new prop shaft.

Here's a video of my test hack at OFFC Wednesday morning. Couldn't get it over 13.5mph at Duarte last Saturday, Changed to a smaller prop and cut the wings back down, in stages, to the original span and got a 24.43 mph flight out of it, probably the limit for that airframe, The vid was taken at the end of the session when the rubber was getting tired. It's only doing 16.34 mph in the video, Has too much incidence, jumps off the ground too soon and flies too high, but I think it give me the parameters for my real racer. Oddly enough, I think a scale D-12 Bonzo would do quite well.
https://www.youtube.com/watch?v=1MoqCCBgFmc

More Later!

KF

Quote:


With videos if I can get good ones.

KF

Sky9pilot wrote on Jan 14^th, 2019 at 3:24pm:


The B.L.U.R. race is for scale models.  (And when I have seen it was fun to watch.)  The RTP race is for pure speed models.  The Covered Motor  class simply has to have a canopy, that's for "plausible scale".  The Unlimited Class can be a motor stick model.  Push/Pull designs have been suggested but they must R.O.G.

The Speed Merchant is a similar model to the Comet Racer, and other speed models of the 1930s, with a 9 inch wing span and is 22 inches long.  The difference is that is intended to be tethered at the wing tip to fly in a circle.  This is something the Black Sheep Squadron did many years ago and it was decided that it would be interesting to revive the contest.  I might also be fun to fly these things outdoors on a B.L.U.R. course.

Here are the rules:

RUBBER POWERED RTP SPEED EVENT RULES
(Preliminary)

Pole

    The pole will be three feet tall with a headed nail in the top.
    The line will be fine sewing thread with a paper clip at each end as a swivel and a hook. The swivel to hook length, including the paper clips is 10 feet. This gives a circle of 62.83 feet.  (1 second lap equals 42.84 mph.)
    A 1/8 inch high, foam, curb is placed across the path of the flying circle at one side as a timing point.
    Three people with stop watches will do the timing unless there is an electronic timing system


Models

    Classes

    Covered motor
        “Plausible scale” (i.e. must have a cockpit)
        Motor completely enclosed by fuselage
        Flying surfaces built up and tissue covered
        Landing gear has rolling wheel(s)
        Detachable dollies allowed
        (If you think you can make that work!)
        Hook attaches at wing tip

    Unlimited
        Motor sticks allowed
        All balsa flying surfaces allowed
        Landing gear has rolling wheel(s)
        Detachable dollies allowed
        (If you think you can make that work!)
        Hook attaches at wing tip

Competition

    For a qualifying flight the model must ROG, from the floor, from any point past the curb and must be airborne and clear the curb at the end of the first lap.
    The timing starts when the model crosses the curb at the end of the first lap. The model is timed for the second and third lap and the speed is calculated.
    Winner in each class is the fastest speed.


These rules are preliminary and will be revised after flight testing and experimentation.

KF

Ian, I have that plan, but never found anyone to be a mentor to build one and as strat-o stated what are the rules.

Bob