HPA

Quote from: PiecostLurker, Is the neoprene flexible or stiff?

The black tubing shown is quite stiff, the clear perhaps a little stiffer than shop-bought O rings.

I'm expecting both to wrap around the hook when I get around to using them.

We now return you to your normal programme.

All that talk about nose dives and I think I should say something about the survivability of the model. Key was the addition of a balsa box to support the thrust button. This should take the load off the fragile plastic cowl.

I also cut a slot into the rear of the balsa cowl ring to allow us to add mass (red clay) as far forward as is practical

Quote from: Spiros on Jul 01, 2026, 07:58 AMFrom this particular flight, I saw a nice glide path. No nose up and in my opinion the "stall" was due to under power and wind on your left wing. You only had 100 turns

I wouldn't try it on a windy day. You cannot come into a conclusion having such windy weather.

I agree that I shouldn't read too much into that day's flights. But two things did appear to be consistent. That is I never got a nice transition from power to glide. I could get some nice glides from a shoulder height launch. And I got a few nice powered flights. But at the end of each powered flight (if I was still in the air) the Zero would transition into a spiral dive, never to recover!

I had about 4 zoom climbs at (200 turns) where the wind drove the nose vertical. The result was that the Zero ended up about 7 meters above the ground hanging on the prop. It then flipped over on its back and dove straight down, making no effort to pull out. It did this about 4 times. I think this is a clue. (I know don't fly in the wind)!

The clue I think I'm seeing is that as the model gains speed in the dive there isn't enough decalage (up trim) to lift the nose towards the canopy. Right now I think the fix is to add up trim to gain this self righting characteristic.  Then add nose weight to find a nice level trim speed. (More nose weight might add some stall margin).

BEAVER DH C2  30 INCH RUBBER POWERED  FREE FLIGHT PARK FLYER  DUMAS KIT 306

Reply # 367     

Wed July 1 2026

Hi Spiros!  Thanks for the  'likes'.   

Quote from Spiros above  " I can hardly imagine this beauty, flying only for 13".

"Why is this happening? Have you tried a straight single rubber? Obviously shorter but definitely could be stronger in my opinion.  "

    That is a good  question,  the all time  question ... .    I was only going for a ten second flight from the beginning.  I think ZKAUD Mike said that he would be satisfied with a ten second flight (where is Mike?).  So,  I was going with that.
      I documented,  first time for me,  the different rubber motors and cross sections and their builds,  and their run times on my handy dandy table stooge,  and the run times outside also.    A power run time of 12 sec on the table stooge,  does not equate to a  12  sec flight outside ...

Pic #1    1739
Pic #2    2695
Pic #3    2726
Pic #4    2859   

"straight single rubber?"  -  do you mean a single strand  ( one half of a loop ),  and what total width cross-section of the rubber strand(s),  of your straight single rubber ?    I found that the best  'pull'  was that  eight strand  motor  of total cross section of  0.813" of rubber motor strands.    Since there is not a  0.813"  width in rubber  (only  3/32",  1/8",  and  3/16"),  I added extra strands sizes of rubber and tested them as I went along.

      I started this rubber powered hobby 14 years ago at age 55,  with the Guillow  Nieuprt 11  24" laser cut kit (totally hooked) just for a display model back then,  so I don't have all the answers.    I think it was Cal Goddard who said it would be good to get a ten second flight with this 30" Beaver plane too.  And I always thought that that blunt nose,  and the enlarged landing gear and no windshield,  were all resistance factors causing shorter flights.

PLUS

Total Wing Area  3.3125" x 30"  =  99.375" sq

Max Weight Rule for Flying is  0.5 g of model weight per one sq inch of lifting surface.

99.375 in sq  X  0.5g per in sq =  49.7 g

The Beaver weighs about 113 g,  so it is way over weight.   

    I am settling in for  'build mode' with the 30" Gipsy Moth now,  in my air-conditioned apartment,  during this heatwave.    No flying for me ...

Lastwoodsman
Richard

Great to hear that.

I could not have helped as the upload works for many people so I would not be able to suggest a solution.

Looking forward for more uploads then

I still need to change the description of the magazine to Australia

George

Oh dear !  A browser issue ........
Downloaded a new browser ( Brave ) and looks to be working !

1 July - Uploads are failing ... Or hanging / failing to complete . 
For some reason ..

From this particular flight, I saw a nice glide path. No nose up and in my opinion the "stall" was due to under power and wind on your left wing. You only had 100 turns

I wouldn't try it on a windy day. You cannot come into a conclusion having such windy weather.

Here is the first flight of the Zero with 100 turns. It really was too windy but what the heck, the wind is from your right. We have about 2 dozen test flight when we quit for the day. We got about 4 flights that did not stress the nose cowl. There was no constant pattern to the flights to aid in trimming. I blame this on the wind. But I'm also coming to the conclusion that I might need more decalage. I measure 3 degrees at the wing root measuring from the bottom of the wing airfoil and the stab.

In this flight and all others I could not get a transition from power to glide. You can see the start of a violent stall to the right (viewed from the cockpit). Other times the stall was to the left. I'm thinking of adding a bit more up decalage and add some nose weight to compensate. In far too many flight where the wind caused the plane to nose up into a prop hanging stall with a flip onto its back. This got the zero up to 5 meters. From here the Zero came straight down with no hint of a pull out. This is leading me to think I need more decalage (up). I'd have expected that as the model gained speed in the dive that the elevator (up trim) would have tried to pull the nose towards the canopy. I never saw the self correcting behavior.

The Zero shows promise both in the initial glide tosses and in the power on section of this video.

https://m.youtube.com/shorts/BHcCiixUQT4?feature=share

For a four strand motor; thread the    loop through the O Ring. Attach one end of the loop onto an anchor, such as a door handle.

Position the O Ring in the middle of the loop. Apply the pre-tension turns. Hold the O Ring and fold the motor, attaching the free end over the anchor.

Attach the winder to the O Ring, and let it dangle and turn to braid the motor.

Only use a single O Ring at the propeller end. No need for one at the peg end. I am not even sure how one could be added there. But, a small rubber band can be useful at the peg end to prevent the motor unraveling. The small silicon Loom bands are a convient and cheap alternative to orthadontic rubber bands.

I have not figured out how to do six strand motor.