nelson whiplash
10-12-2002, 07:58 PM
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nelson whiplash
Two flights today. Tach 21,300 with 15% nitro, 7.4x8 prop. Radar gun 163 mph. This engine doesnt seem to unload in the air at all. It basically sounds the same as on the ground as in the air. Am very interested in jett 50 data.
10-12-2002, 10:03 PM
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nelson whiplash
IT'd known that Nelson Q500 will not unload that mucnh in the air 'cause it have longer pipe than Jett, maybe it's the same with the qm40...
10-12-2002, 11:12 PM
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Nelson Q500 props
The reason you're not getting the motor to unload in the air, is that you have it maxed on the ground. Run a larger diameter prop and see how much faster you go. You need more pull to get the max speed out of it. Props with a diameter less than 8" just will not pull the plane. It's like paddling a canoe with a really short, skinny paddle; you get a lot of strokes in, but the canoe just doesn't seem to get anywhere. Try a 8-8 or a 9-8 APC sport prop, then go from there...Let us know how it goes... A standard pylon prop is great for a high lift quickee with a narrow wing chord and weighing in at 3.5 pounds, but the Whiplash is simply a different airframe. Give the larger props a shot. They really do perform better.
10-13-2002, 12:17 AM
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nelson whiplash
Sorry but i realy doubt that any QM 40 engine will turn a 9 diameter prop...You should try 7xsomething to get proper rpm...I think any q500 engine should turn at least 19000 on the ground ( with 8.8 or 9x something )so any QM 40 should turn at least 23000 rpm on the ground( with 7.something x somthing )
10-13-2002, 12:38 AM
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nelson
Yea it looks like i have the wrong engine for this application. I'll see what happens as i increase size. I have a 7.5 CF APC and other pylon props in the 8 inch range. With my holder i can switch props and tach easily. The trick is going to be right prop with right mixture to get it unloaded and on the pipe in the air.
10-20-2002, 07:18 PM
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single blade bolly
Dont know anything about single bladed stuff. I cut my 7.4x8 down to 7.25 and got 23000 out of it on the ground. Thats good for 175 mph. Still waiting for spiderman. Jett fire 50 ready to run.
10-20-2002, 08:52 PM
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J,
I don't think you have enough thrust. A 7.5 inch prop is fine for a 3 pound Dust, but forget it with a 4 pound Whiplash. Rick and Dan are running 9 inch props.
On my Whiplash I plan to run a 9X10 with a Jett FIRE 50.
When I was running that combo on my Dust I was taching 16.5K on the ground, launching at 15.5 and believe it was unloading several thousand in the air.
I don't think you have enough thrust. A 7.5 inch prop is fine for a 3 pound Dust, but forget it with a 4 pound Whiplash. Rick and Dan are running 9 inch props.
On my Whiplash I plan to run a 9X10 with a Jett FIRE 50.
When I was running that combo on my Dust I was taching 16.5K on the ground, launching at 15.5 and believe it was unloading several thousand in the air.
10-21-2002, 12:13 AM
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7.25 diameter prop
Your right. On launch it is barely enough. But with the qm40 engine im stuck. Still not hitting the pipe yet. Going to shave a little more. The 9x10 @15.5 is not much more thrust on launch either. On the 4.5 pound plane its going to be shakey. I saw on another thread someone using a 7x9 prop on a DD. That will not work on a whiplash.
10-21-2002, 08:54 AM
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nelson whiplash
yesterday we compared my DD (with Jett FIRE 50 engine and tuned pipe) with the Magnum (with West Eurotec V150 (modified Webra 50 engine) and tuned pipe with muffler).
the Magnum with APC 9x7 (17% Nitro) seemed to be as fast as my DD although it did not unload in the air as much as my DD did.
ground measurements:
West Eurotec 18.400rpm with 9x7 APC
!!!!!18.000 with 8x10 APC!!!!!!
Jett Fire 50 17.400rpm with 8x10 APC (15% Nitro)
BTW: remember half the price of the West Eurotec engine.
I fear the Magnum with 8x10 APC will outperform my DD by far.
do you guys think, there is a nelson outthere, that will give better performance and speed for the Magnum than the West Eurotec?
mec
the Magnum with APC 9x7 (17% Nitro) seemed to be as fast as my DD although it did not unload in the air as much as my DD did.
ground measurements:
West Eurotec 18.400rpm with 9x7 APC
!!!!!18.000 with 8x10 APC!!!!!!
Jett Fire 50 17.400rpm with 8x10 APC (15% Nitro)
BTW: remember half the price of the West Eurotec engine.
I fear the Magnum with 8x10 APC will outperform my DD by far.
do you guys think, there is a nelson outthere, that will give better performance and speed for the Magnum than the West Eurotec?
mec
10-22-2002, 03:40 AM
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Magnum wing loading
Just curious,
What's the wing loading on that tiny airframe with that .50 and pipe combo? I think that the greatest thing that most seem to miss is that it takes a lot more to going fast than a tiny airframe and a big motor. Lots of factors involved. The only way to really compare two different airframes is to run them in the same place under the same exact conditions. There are just too many variables...Anyway, we all like going really fast with whatever type airframe we choose; it just never seems fast enough...
What's the wing loading on that tiny airframe with that .50 and pipe combo? I think that the greatest thing that most seem to miss is that it takes a lot more to going fast than a tiny airframe and a big motor. Lots of factors involved. The only way to really compare two different airframes is to run them in the same place under the same exact conditions. There are just too many variables...Anyway, we all like going really fast with whatever type airframe we choose; it just never seems fast enough...
10-22-2002, 12:02 PM
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nelson whiplash
Dan,
I have both planes and the Magnum grooves better than the Dust. I think the Magnum gets the edge because it keeps the speed up better in turns. Both are very fast.
Mark M.
I have both planes and the Magnum grooves better than the Dust. I think the Magnum gets the edge because it keeps the speed up better in turns. Both are very fast.
Mark M.
