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Jun 13, 2019, 07:46 PM
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Interesting that the estimated 85 mph is only 63 actual. I should get a tach reading on the ground sometime soon. I guess I am famous on Utube now. I didn't want to register.
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Jun 13, 2019, 08:30 PM
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Your video has received 42 views as of last night when I posted it.
It's good to see Aspeed enjoying the hobby, first flying vid that I know
of. I posted on CEF so folks that don't have FB could see your entry.
You mentioned putting a TD on the nose if able get a vid of that for
a shot at winning send me a link! I will make sure as much data is
on the competition thread.

Line drag is a beast amazing how much rpm is needed to get a good actual.
Unlike RC flying the plane is completely allowed to be let loose, just cutting air
and not drag lines / .08 x 2 x 32ft. adds up. 74.12% in this case was converted
to actual, for a reed engine this is a good percentage to know. I guessed it was a
4.5x4 sure looked like one yes? Back cut that prop and get instant performance leaving
the dia. to keep the thrust up. The APC 4.4x4 is also a IC prop but advanced design
effort to increase performance in comparison to the 4.5x4 worth checking out.
Last edited by 1/2A Nut; Jun 13, 2019 at 08:48 PM.
Jun 14, 2019, 07:16 PM
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I used a 4 1/4 - 4 APC on that flight. I had been using an old old old Tornado 5-4" that was cut down a fair bit. I am lying to say cut down. It was ground away from doing touch and goes on the parking lot. It ran about 2 mph less. The tips were not trimmed or shaped. It was vibrating a lot more than the APC likely because it was not balanced. I used it first in case it would nose over on landing and break. It did tumble a bit, but things seemed fine. It is difficult to find small props at any hobby shop around here. It all needs to be ordered. I guess I am famous now with the Utube thing. I was flying at the Brodak meet in Carmichaels Pennsylvania and won the Clown race with 4 in the circle. I am just a pilot whore and had nothing to do with the plane. I would like to see video of that if anyone has it. I heard reports of swarming bees. A few close calls nearly cost everyone's plane. Pretty crazy. I lost 5 lbs over 3 days. Got second with the Foxberg race too.
Jun 14, 2019, 10:13 PM
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Back in 92 I had a TD .49 powered CL plane with minimum sheet wing
foiled for flying over grass had to be hand launched no landing gear
very good power to weight. Think I flew it on 30ft. lines as I recall. The
plane had pretty good pull for it's size do to the speed. It was seemingly
fast but 4P was the limiting factor my guess it unloaded to 27k from
what I know. 102 mph pitch speed and perhaps actual due to it's
minimum size / weight around 78 mph. Thrilling when your hand and
arm is part of - connected directly to the action. These days with all
the APC props sizes on hand would be using 5P to bust the typical
speeds a cut APC 4x5N leaned up to hit 27k unloaded would yield
128 mph prop pitch speed and likely do around 90 +

Alan your flight entry was able to be reviewed on CEF and has hit 63 views.
Not bad for a Black Widow CL vid. in just a few days. Look forward to seeing
what the TD does with that plane next.
Jun 14, 2019, 10:58 PM
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Ya I am waiting for the field to dry out. More rain for the weekend, and 3 days to dry out, then 2 more rainy days. Not looking good for June. I would not expect 80 mph because 45 years ago when I did it, there as a lot of nitro, and I don't think I will be mixing any up. Maybe 15% . I'll see. I could maybe mix up some and retry the Black Widow again too. They don't use much fuel. I guess it depends on how long my launcher stays around. The 1/2A speed guys are running around 40,000 rpm now and around 140 mph I think. With no slippage or drag that is 3 1/2" pitch. They probably use 4-5" pitch single blade props. IDK. I have not gone to the nats for a few years. I got a video of a jet at Brodak that is kind of kool but don't want to embarrass the pilot. I bet there would be some views.
Jun 14, 2019, 11:39 PM
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Yea I would just stick to the TD if you want to win the "Run what ya Brung* Unlimited Speed Contest" folks at CEF like them Cox TD engines!
Jun 15, 2019, 07:29 PM
mjd
mjd
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Quote:
Originally Posted by aspeed
Interesting that the estimated 85 mph is only 63 actual. I should get a tach reading on the ground sometime soon. I guess I am famous on Utube now. I didn't want to register.
Not unusual - the logical conclusion from such a spread (if validated) that is that you're not there yet with the prop. The total drag prevents that engine/prop combo from approaching pitch speed - which is no more than the theoretical "zero-slip" forward speed*.

* unless there a bugger factor in the math, pitch speed assumes the pitch number is the true aerodynamic pitch, which is not the bottom datum line pitch given by a simple pitch gauge nor is it the chord line pitch derived from the line joining the LE and TE peaks. Numerically it's higher than either.

Based on 22.5k flight rpm, I'd guess 3.5" is closer to optimum pitch for that model with a pitch speed of about 74mph. The reduced load from higher L/D and lower pitch could be traded for a bit more blade area or disc area. I could also be barking mad, but I'd be curious how the 4.2x4's next door neighbour in the catalog, the 4.5x3.5 or an e-prop equivalent might do as an alternative.
Jun 15, 2019, 08:46 PM
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The 4.2 - 4" is a very thin and narrow blade so it must slip a lot. It was very close to to old thick beat up Tornado air speed though. I do have a pitch gauge if I can find it. It isn't really important to win the challenge other than for bragging rights. That is a factor. It goes by votes and chrome and anodising makes a better impression than 5 mph with these guys. Hmm I think I have a 4.75 - 4.75 electric prop somewhere.
Jun 15, 2019, 09:16 PM
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There is a new prop from APC 4.4x4 it is for IC use made for CL 1/2A it has a wider section of cord aggressive enough to tap
into the engines torque while keeping the rest of the length typical in width. Should add some thrust to pull those lines along.
Someone has influenced APC to produce it this is good for CL efforts. It made good thrust with a TD static 23.5k rpm.

If you go with a 4.75 x 4.75 will need to cut it down. 4.2x4.75 should yield 70 mph + I have no problem reshaping props, the
payoff has brought quite a bit of speed and jumped the engines up to 5.5P thus far. There is no reason why those lines can
get dragged faster may take a few laps to get to peak speed. Alan's Black Widow engine had good fuel flow during the early
laps I could hear the rpm drop and see the readings fall mid way through the run.
Last edited by 1/2A Nut; Jun 15, 2019 at 09:28 PM.
Jun 16, 2019, 12:56 AM
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Classic C/L Speed Cox .049 - Salvi Angeloni (1 min 39 sec)



Peterg2yt
Published on Dec 26, 2015
Salvi Angeloni (Italy) showing the Brits how to go fast at the 2013 British Model Flying Association National Championship
with his beautifully constructed 'Twister', designed in 1954 by Lloyd V Hunt (USA).

This model is constructed using traditional tissue reinforced Balsa and is powered by a Cox Tee Dee .049 engine from 1961,
making it eligible for the Classic Speed class. Fuel tank is 7cc capacity. Fuel is a mix of Methanol, nitromethane and castor oil.
Propeller cut APC 4.5 x 5". Speed is about 85 mph on 42' music wire lines. This model weighs 145 gr.

Salvi explained that the model was designed as a trainer for Control Line speed flying and he has made a range of sizes for engines
from -020 to .40 cu. in. size. He said they all easy to fly, fun and cheap.
Jun 16, 2019, 01:20 AM
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This was as good as it gets for the wee 10cc tank 60% movement
with the clunk tank inverted around 4 ish minutes of heavy acro.
Made for the TD .010 if I use a throttle sleeve with typical throttle
use during the acro dance should do 5 mins. about 7 ish minutes if
left at full throttle with small speed props. Need a stunt prop for
this engine a 3.5 x 3NN

Last edited by 1/2A Nut; Jun 16, 2019 at 05:27 AM.
Jun 16, 2019, 12:02 PM
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Vintage Tee Dee pilot wings.

Last edited by 1/2A Nut; Jun 16, 2019 at 02:51 PM.
Jun 16, 2019, 09:16 PM
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Adding this worthy flight to the speed thread:

Flashback Moment to "Fall S M A L L 2018" (2 min 55 sec)

"Fall S M A L L 2018"
Flown by Tony / plane owner set up by Mike.

Profi Ranger .05
Static blue fiberglass VY 4.49 x 3.15 combat prop:
32,984 rpm / 19.75 oz thrust / .33hp - 246.2w / 98.3 mph pitch speed

Best pass 43,874 rpm / 130.8 mph pitch speed / when the engine leaned out and quit it peaked at 51.3k rpm!

Clearly can use more prop such as a 4x5 the current prop unloaded an extra 10,890 rpm typical sweet spot between
thrust and rpm is 6k rpm gain when unloaded. Should be able to hit 160 + mph pitch speed is doable with a 4x5
Last edited by 1/2A Nut; Jun 17, 2019 at 07:45 AM.
Jun 17, 2019, 03:06 PM
Registered User
Well, it did hit 164mph.. with a 4.5" pitch prop (Eliminator E-3 at about 4.1" dia as I recall). That works out to about 38.5k to make pitch speed. Your analysis said it had unloaded just over 40k, so the numbers jive with some slip factored in.
Jun 17, 2019, 04:24 PM
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Ok updated the pic with the cell phone vid using the eliminator 4.1x4.5. I think a 5P prop will bust 170 mph +
Have you tried running the engine without crankcase pressure and the profi pipe? If the engine runs less fussy
and holds steady on the ground figure 3 clicks richer for flying. Sure would be less noisy bit more field friendly.

Last edited by 1/2A Nut; Jun 17, 2019 at 06:29 PM.


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