Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

Magnum Weston 50 Prop Size

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Old 03-05-2006, 09:53 PM
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JetKing340
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Default Magnum Weston 50 Prop Size

Hi guys, what brand and size props do you run with your stock Magnum with Weston 50 and pipe combo...?

I'm thinking of putting an APC 8x9 on mine, I want feedback and experiences. I have mine about 85% complete now, just basically drop in the servos and balance, so I'm getting to the point where I need to put a prop on that engine up front...

I'm welcome to your opinions, I really don't want to cut the header....

Helimanik
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Old 03-06-2006, 04:52 PM
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MJD
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Default RE: Magnum Weston 50 Prop Size

Started with APC 9-6 for run-in and test flying, then APC 8-9, then when the snow's gone will putz with various APC pylon props. You're okay with the APC 8-9. Weston's recommendations for best performance are:

8-8 1" off
8-9 1/2" off
8-10 stock

But, it will run well with the 8-9 at stock too, although you might lose a few rpm off the top when unloaded. The 8-10 can be tricky at launch - some people have no trouble, some have a little; it depends on how hard your helper tosses it, air density, CG location, how strong your engine is running, all up weight, yada yada.

Where are you setting your CG? The rearward recommend locations are not "rearward" but "less forward" so don't be nervous about them.

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Old 03-06-2006, 04:56 PM
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Easystern
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Default RE: Magnum Weston 50 Prop Size

Hi HeliManik,
i am in the same progress as you ,i got it ready 90 % with the weston 50v and pipe. i will start with a 9x6 apc to get better feeling on the start when my buddy will throw it . i am reading now since 3 days all forums about that plane in europe and the states.
i found out that most of the fast guys like the 8x8 with a shortened pipe at around 21000rpm.one guy had shorten it 1 inch to get the max rpm with the 8x8.
but before i will cut it, i will call weston uk to find out where to cut and how short the pipe has to be.
the throw at the start with a 8x8 needs more push to get the prop bite into the air and some tell it has a tendency to roll left from the torque of the engine right after the start with the 8x8.with the 9x6 or 9x7 it looks like that most of the magnumers has the best and save start and the prop will take it right out of the starters hand.

i will start right from the beginning with 20% cool power to get a good trotle responce and power out of that engine.but i need more info about the plug heat range and brand for the 20% fuel.

what fuel will you use ?

keep us updated with your first flight, i will have my maiden end next month when the weather willl be nicer here in germany.



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Old 03-06-2006, 05:09 PM
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Default RE: Magnum Weston 50 Prop Size

ORIGINAL: Easystern
but before i will cut it, i will call weston uk to find out where to cut and how short the pipe has to be.
the throw at the start with a 8x8 needs more push to get the prop bite into the air and some tell it has a tendency to roll left from the torque of the engine right after the start with the 8x8.with the 9x6 or 9x7 it looks like that most of the magnumers has the best and save start and the prop will take it right out of the starters hand.
The recommendations I posted above come directly from Alan at Weston. He also said that while they like the 8-10 for highest top speed, they have occasional problems on the launch. Alan said that every once in a while they fail to climb out after launch, so they break a prop and have to start over again.

Yes, with a 9-6 or 9-7 launches are no problem but you lose a fair bit of top speed. The 9-6 is a good prop for running in the engine and for first flights.

Also - when using these sport props, ensure that the spinner cone does not touch the leading or trailing edge of the prop. Contact at either of these spots has been blamed as one cause of props fracturing. The rpm limits of these 8" props is, per APC's formula [http://www.apcprop.com/html/rpm_limits.html ] 23,750 rpm. So we are running very close to that limit and need to watch prop safety issues closely.

MJD

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Old 03-06-2006, 11:12 PM
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Default RE: Magnum Weston 50 Prop Size

Why dont u use pylon prop???
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Old 03-07-2006, 06:31 AM
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Default RE: Magnum Weston 50 Prop Size

hi glorfindel

what typ / brand and size do you recommend ?

i would say the design and shape of the apc sport is for tractors and not for speed planes, they are ok but i think you will get more speed out of a prop what is made for 20000 to 30000 rpm.
i have 1,5 years now of experience with high speed planes now, since i started this hobby 1,5 years ago and thats not a long time to learn but as a racer i can say that one of the most important factor is to bring oll that power into motion !!, is the prop beside of the other factors to go fast.
i have a couple of high speed pylon elektric powered planes in the 160 mph range and if i look at the shape and on the cad cam design of my mostly used cam speed props from graupner they look a way more aerodynamical as the old fashion sport from apc.

on my last fuel powered plane with the os 65 i was using a cam prop 11x8 #1360 28 20 instead of the stock design 11x7 graupner(similar to apc sport) what they recommend , i got 11800 rpm that's 800 rpm's (static) more out of the engine even with one inch more pitch and it was a way faster with also higher climb rates and that was a trainer brick, just with changing the design of the prop to a 20 century design prop.

this year i start a new range of speeding with bigger fuel powered planes and i have to learn more on this type of sport.

feel free to give me more of that knowledge to go through the air real fast
thats wy i have to say thanks to all my speed brothers here on that board !!!

sorry about my spelling i am a german
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Old 03-07-2006, 09:46 AM
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Default RE: Magnum Weston 50 Prop Size

There does not seem to be a lot of people who have experimented with pylon props on Magnums, at least not a lot o fpeople that have reported here. I bought an inventory of APC pylon props for experimenting this spring. I have a number of 8.8" props in the 8.5 - 9.25 pitch range. Once the weather warms up I will experiment with those on the West .50. Likely I will have to trim them a bit to unload the engine enough, but we'll see. Many people are nervous about running the sport props at those rpms. MJD
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Old 03-07-2006, 05:07 PM
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Default RE: Magnum Weston 50 Prop Size

Hi,

I'm using a Jett Q500 engine on my speed plane. I think the Weston engine is comparable in power/rpm to my .40 Q500 engine. So i would recommand you to start with the apc 8.75X9W, nickaname : 'the screamer' This prop is a good all around, high rpm one. If i was you i would buy a 8.8.x8.5, 8.75x9w, 8.8x9.0 and see how the engine/pipe respond to it. You have to swing it more than 19000 on the ground.

For the first couples of flights, to have a good static trust you can try a standard 9x6 apc.
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Old 03-07-2006, 11:01 PM
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Default RE: Magnum Weston 50 Prop Size

Hi, I am running the Jett .50 with their Super Sport (shorter) tuned muffler on it and the APC 8.75x9W on my Magnum. This is a nice combination, so far no problems on launch, though it does take a little while to accelerate, and the top speed is the fastest of any plane I've owned. I believe the Jett .50 and the Weston .50V1 are pretty comparable on this plane. I haven't put the tachometer on it yet, but estimate 19,000 rpm on the ground and significant unloading in the air. The previous owner of my Magnum also had a Jett .50 on it (don't know which muffler nor which prop he used), but he said they clocked it at 158mph with a radar gun on the straight and level. After flying it a few times now, I have no reason to doubt him!
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Old 03-08-2006, 02:20 AM
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Default RE: Magnum Weston 50 Prop Size

This might sound like blasphemy, but my Magnum was the same speed or faster with the 9x7 than the 8x9 and 8x10 that i also tried.

Plus, the 9x7 was MUCH easier to hand launch (my Magnum actually sank into the ground on one of my launches with the 8x9).

Seems like the 9x7 is a win-win to me (but now I'm starting to think about popping on the 8x8 ).


Here's a video with the 9x7:

http://www.resume-connection.com/Rea...omePass9x7.mpg


and here's a video of the 8x9:


http://www.resume-connection.com/Pas...opBestPass.mpg

Which do you think is faster??
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Old 03-08-2006, 11:47 AM
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Default RE: Magnum Weston 50 Prop Size

Hi,

It's not a blasphemy, it's only thet the engine cant swing it But if you tried a 8.8x8 or 8.8x8.5 or a 8.75x9w it should be faster.

I'm very interested in the RPM you've got with the 50 and an APC 8.75x9W to compare with my q500
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Old 03-08-2006, 01:49 PM
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Default RE: Magnum Weston 50 Prop Size

cobra

thanks for the videos, very nice

the 9x7 looks way faster to me , i found a vid here from robert92679 what he had posted last year
thats an 8x8 with schortened pipe header and i would say the engine revs very high and its fast.
ok its http://www.rcuniverse.com/forum/m_2716222/tm.htm hard to tell if you see it on a vid .

i think also the air density (oxigene factor) and see level plays a big rule to get high rpm out of the engine.
and cobra i see that you are flying at noon or in very hot conditions.the oxigene is tat highest point at the evening i had the best result on that time with hi po engines sometimes i felt 10% more power than under bad condition.

see level plays a big role to, i dragrace cars since 20 years and high level tracks are half a second slower in the quarter than see level
tracks, i have to search for the formula to calculate different speed caracteristics on dif. atitude levels and i will post.
on our small high reving engines it can be all of that factors that you can, lets say .... on low level afternoon flights the engine will rev with a 8x10 21000rpm and under the badest condition high level at hot noon it would be hard to get out 19000 with a 8x8.

but thats all teoritical and i have to test this summer all that factors[8D].
I bought an inventory of APC pylon props for experimenting this spring. I have a number of 8.8" props in the 8.5 - 9.25 pitch range. Once the weather warms up I will experiment with those on the West .50. Likely I will have to trim them a bit to unload the engine enough, but we'll see. Many people are nervous about running the sport props at those rpms. MJD
MJD....
please keep us udated on that testing in the future it will help us a lot and it helps me very much to make my baby fast for
september this year where i will be a contender at the one and only/yearly speed cup chalenge in germany ,
http://www.mfc-osnabrueck.com/Speedcup2006.htm
and if i can make it to get in the top ten ranks that would be a good satifaction for me and the magnum.
http://www.mfc-osnabrueck.com/Speedfliegen.htm
the fastest last year was 229 mph(369kph) mesured with doppler
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Old 03-08-2006, 02:33 PM
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Default RE: Magnum Weston 50 Prop Size

glorfindel...

thanks for the answer i have taken a look at APC http://www.apcprop.com/cgi-bin/store...c=6a&product=+
what is available as pylon props and it will be a good idear to start with a 8,75x9 trim to 7,75 or 8 and try.
most of the guys here got best results with the 8x8 on the west50.

i am very excited about that new magnum project, cant wait to get this sh... weather away here .

i think you are dealing with snow also right now in canada
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Old 03-08-2006, 07:26 PM
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Default RE: Magnum Weston 50 Prop Size

Hi,

Yup a lot of snow here by now

8x8 is too small for my Q500 engine.

Do you think that my Jett Q500 outperform the West engine?
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