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Old 09-10-2018, 05:42 AM
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Updated rpm / thrust

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Originally Posted by pelle_gris View Post
3W-210Xi B2 TS.
3W XL/150 canisters, about 19 cm / 7,5" headers.
Twin RCexl ignitions.
Sea level, temps around 20 C.

SEP "Scale" 30x12x3: 5.200 rpm Very quiet but crappy idle due to the low diameter. (34,5 kg / 76 lb thrust)
SEP "Scale" 32x14x2: 5.000 rpm. Fairly quiet, good thrust.
SEP "Wilga" 32x14x2: 4.450 rpm. Very quiet, but also lower thrust it seems. But it could be the lower sound that gives this impression. (33 kg / 73 lb thrust)
Fiala 34x14x2: 5.600 rpm. Very loud, good thrust. (37 kg / 81,5 lb thrust)
3W 32x12x2: 6.250 rpm. So loud I felt slightly sick for about an hour after running it in my driveway!!

Still to test.
SEP "Power" 33x14x2. Not hopeful as a friend ran this on his 3W 200 TS CS, and it started to rip the prop from 50% throttle. With the props tested so far the 200 CS pulls about 100-200 rpm more than my 210 TS.

Not that impressed with the canisters as they seem to be much louder than the Zimmermann and KS canisters I have used previously.
Considering trying a set of JMB canisters, as they are quite cheap, and from what I have read also dampens the noise well.
Updated the above with latest readings / thrust in red.
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Old 09-17-2018, 09:12 AM
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RCGF 60 side exhaust, just had to let others know about this engine. Smooth running with no rich midrange.It beats my DA 60 in rpm and smoothness.

Falcon 24-8 carbon 7290
DA50 side dump
32-1 redline
800 ft, ASL

Just an update after getting some time on this trouble free engine.It's now just hit 7410 with the same prop and muffler.
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Old 09-17-2018, 09:55 AM
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That is good. 7290 RPM with the 24x8 Falcon on stock is about 32.8 lbs of measured thrust from my prop tests and a calculated pitch speed of 55.22 mph.

We were getting 6810 RPM from the 24x10 Falcon at sea level and a 88*F air temp here in FL with a safe-rich mix on the DA-60 for 35.7 pounds of pull on the digital Rapala and a 64.5 mph pitch speed... with the RE2 pipe.

If you go back here and look at the DA-60 and EME-60 data, you'll find the DA numbers to be very close to the one's I just posted, and the EME60 will be these (or at least the ones I collected) on stock...

Xoar Lam 23x8 7100 RPM
Xoar Beech 23x8 to 7200
Xoar Beech24x8 to 6700
Xoar Carbon 23x8 to 7300
Vess 24A to 6910
Falcon CF 24x9 to 6570
Vess 24x10 to 6660

I'm not sure I've seen a lot of RCGF 60cc data so I'll go back check again when I have time.

The only GP61 data I have is with a 24x9 Falcon on a pipe to 6900 RPM.

In comparison, the DA-70 reports here on stock type muffs are generally between 6880 and 7100 RPM with the 24x10 Mejzlik or the 24B Vess Stealth.
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Old 09-17-2018, 01:56 PM
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I know,not much data on the RCGF60,thats why I posted the numbers.I should try the Falcon 24-9 off the DA70 just to see what it will do. I'm empress with it after a summer of flying.
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Old 09-24-2018, 03:35 PM
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If you can get 6800 RPM with the side dump at 800 ft with the Falcon 24x9 from a ground test, you should be pretty happy with that. From my calcs, you should see about 32 lbs of pull on something like a digital Rapala. A 24" carbon gas prop at 6800 RPM is also about 5.36 HP.
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Old 09-24-2018, 05:20 PM
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Thanks for the info it's good to know that someone is doing what Pe Reivers did with prop data.
I use to have a GP61 on a side dump and it got 6850 with a Falcon 24-9.It was satisfactory but I really like 60-70 size engines in the 7000+ range.Like the DA70 and a Falcon 24-9 at 7450 is GREAT. I have that in a 18lb. Aeroplus Extra.
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Old 09-24-2018, 08:07 PM
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RCGF 60 Single with DA 50 Slimline side exhaust, Bjorn Baal rings, Falcon 24x9 Carbon getting 7000 rpm static. This combo pulls an Aerobeez Extra 93” very easily
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Old 09-25-2018, 07:41 AM
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Quote:
Originally Posted by closetguy View Post
Thanks for the info it's good to know that someone is doing what Pe Reivers did with prop data.
Pe was a great man and I'm both proud and sad that I was part of his last conversation on FG. We shared the elusive mathematical aspects of power calculations, and we discussed prop constant down to the aspects of angular momentum.

It was soon after he passed that I finalized the formulas and used electric motor systems to verify prop load and develop specific constants for the more common props. It was then that I realized that pK was not a constant at all, but a variable determined by RPM. This would actually make sense to anyone who studied the physics of rotational energy (angular kinetic energy).

The key to verification by electrical power is the relationship most people overlooked between the motor Kv, the loaded RPM/v, and the torque constant (Kt).

Amps = (((Torque in lb-ft*192)/1352.4)*Kv)
Where 1352.4 is the constant and 192 is the conversion to oz-in.

So all I need to do is verify the motor Kv, use a constant voltage source, and measure RPM and current as accurately as possible.

The best thing to come out of this was the calculation predicting actual measured thrust. This became a simple relationship between torque and the disk area. For gas props, it ends up being just a more precise version of Pe's rule of thumb of the HP times a value of 6.

So his estimate off my 5.30 HP calculation for a 145g 24x9 carbon Falcon at 6800 RPM would be 31.82 lbs of thrust and the calculated version at 77 to 85 degrees F would be 32.05 lbs.

There are air temp, altitude, sizes, and RPM, where the difference is a little more pronounced. But you can see how his contribution continues to be a valuable rule of thumb since no one would really notice the difference in the real world even if we were able to get precision accuracy in our RPM measurements.

It's all a rule of thumb anyway, and my testing on 153 different prop and motor combinations did nothing more than find out how he may have come up with it in the first place, but did verify what he told us in the first place.
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Old 09-29-2018, 02:42 PM
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DA60 no. 2, well broken-in.
7380, Falcon 24-8,stock side dump muffler,32-1 redline.
800 ASL.
This MIGHT be a little to much rpm for even me,24-9 may be needed.At this rpm it sounds like it's ready to come apart.
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Old 12-13-2018, 04:41 PM
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DA 70

7560 rpm on a Falcon 24x9 carbon prop, results are after 10 minute flight

60% humidity
85 degrees
4mph breeze
and my elevation is 1463

Im now useing a xoar laminated 24x9 to tame the rpm's a bit


Desert Aircraft DA 70cc falcon 24x9 at 7560rpm (0 min 34 sec)
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Old 12-13-2018, 04:59 PM
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I think that's the highest rpm I have seen for a DA70,you got to love that engine.Anything special about the mufflers,like larger exit tubes than stock mufflers.
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Old 12-13-2018, 07:57 PM
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Quote:
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I think that's the highest rpm I have seen for a DA70,you got to love that engine.Anything special about the mufflers,like larger exit tubes than stock mufflers.
I dont think there is anything special with them 40mm cans 25mm stingers, I just got real lucky and got a good DA70
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Old 12-14-2018, 05:09 PM
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Old 12-14-2018, 05:52 PM
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I'll stick with the 24-9 Falcon, amazing prop on the DA70.
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Old 12-14-2018, 09:53 PM
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Quote:
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I'll stick with the 24-9 Falcon, amazing prop on the DA70.
Im with you
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