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

Speed beginner, few Q's?

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Old 05-12-2006, 03:38 AM
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Test005
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Default Speed beginner, few Q's?

Hi
I've ordered two Webra 50GT's and 9x8 APC's and want to try out some speed flying down the line.
I normally fly fourstroked sportplanes and have never had anything really fast.

I was thinking to get a GP Viper for my new Webra's.

-Is the 9x8 good for this engine/plane combo?
-How much rev can I expect (used to low revving 4c engines)?
-What speed do you estimate on this setup? (Standard size radio gear)


Thanks in advance.

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Old 05-13-2006, 04:37 AM
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Default RE: Speed beginner, few Q's?

/Edited
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Old 05-13-2006, 04:56 AM
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HaveBlue
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Default RE: Speed beginner, few Q's?

hey settle down...not all of us use a webra 50GT.. it would be best answered by someone using this engine.. a 9 X 8 is a commonly recommended speed prop for an engine of this size..I use one on an OS50SX but my info wouldn't be much good to you..it all comes down to experimenting to see what best suits your engine airframe combo.. the 9 X 8 equipped Webra 50GT on a viper will certainly keep you on your toes.. I'm sure someone who has one will come along..patients is an admirable trait!!
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Old 05-13-2006, 05:16 AM
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crasharama
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Default RE: Speed beginner, few Q's?

Mate,
Like Haveblue said, it might take a couple of days for the boys to answer, it is normal for us to have to wait, as we are in a diferent time zone in this part of the planet.

That combo should be quite quick

Tony.
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Old 05-13-2006, 10:19 AM
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Test005
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Default RE: Speed beginner, few Q's?

Thanks, and sorry for being inpatient.


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Old 05-13-2006, 12:38 PM
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Default RE: Speed beginner, few Q's?

No worries
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Old 05-14-2006, 12:47 AM
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Default RE: Speed beginner, few Q's?

Other props to consider: 9x7 and 8x8
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Old 05-14-2006, 06:28 AM
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Default RE: Speed beginner, few Q's?

I already have a few APC 9X7's and have ordered 9X8's.
How much rev should I look at and where's the rpm limit to having this engine underproped/over revving?
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Old 05-14-2006, 10:23 AM
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Default RE: Speed beginner, few Q's?

According to this:

http://www.rcuniverse.com/pgarchive/...peed_50_GT.htm


The high rev range seems to be 16,500 RPM.
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Old 05-14-2006, 02:24 PM
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Default RE: Speed beginner, few Q's?

My stats are:

Webra-50GT
Stock Muffler
5% Nitro
Idlebar plug
APC 9x8
16.2K @ 75 deg and 1,500 ASL

I fly a Patriot ARF with the Webra and it has the fastest throttle response of any engine I have owned (besides Jett-50) in 25 yrs-

I do not guess speeds but a viper/Predator with the Webra 9x8 combo will lite your hair on fire if you are not used to fast planes

FYI the Rossi-45 with mini tuned pipe gives up 600 RPM's to the Webra with this combo but pulls the fun-fly props faster by 400 RPM's
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Old 05-14-2006, 03:15 PM
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Default RE: Speed beginner, few Q's?

Thanks for the good replies... As I said, I have no previous experience with speed planes. I have been looking into a fast set-up for some time and wanted to try, but some other project always got in the way. Anyway, today I ordered a 'Great Planes Viper 500', so my set-up will be:

Webra 50GT/GP Viper 500
APC 9X8
OS #8 plug
Byron 15%
Standard Futaba RX, Futaba servos and a 800mah pack.



Any tips on what to look out for when flying a speedy plane for the first time?
...And even if it's very difficult, can you tell me a ballpark number on the speed I should expect with this plane?
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Old 05-14-2006, 05:54 PM
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Mike Connor
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Default RE: Speed beginner, few Q's?

I would quess a speed of around 125 mph. I would also kill the engine on short final to same props. It will not taxi well so have someone hold it on the runway and let go at full throttle. It will fly like a fast sport plane but will slow down.
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Old 05-14-2006, 09:29 PM
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Default RE: Speed beginner, few Q's?

Run 5% in the Webra-

Get the CG spot on (as with any plane) and make sure you have normal rates and really LOW rates so you do not overcontrol the airplane-

I was gonna guess 120-130 but Connors beat me to it and he knows his stuff-

Cheers!
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Old 05-15-2006, 02:45 AM
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Default RE: Speed beginner, few Q's?

Thanks..Wow, 125mph translates to 200km/h, that's really

I understand it's hard to estimate the speed, but at least this gives me an idea on how fast it is.
I have a feeling I will get a few "How fast is it?" questions at the field, so a rough estimate is good to know.

Normally I don't use dual rates, that was a good tip...guess I need some really low rates for the higher speeds and a higher one for landing to get that elevator to flair out.
This is going to be fun... and I will let you know how it turns out.

ps. I know the Webras run on low nitro fuel and I have to do some testing on which fuel to use.
I normally run my fourstroke engines on Byron 15% and would like to only use one type of fuel so I need to find a good midle way for both types of engines...Perhaps switching to 5% for them all.

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Old 05-16-2006, 02:24 PM
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Default RE: Speed beginner, few Q's?

Test- Cool keep us posted!

I take-off, fly, and land on super high rates even on my Patriots and Whips but I use a bit of expo to soften the stick around center--- A lot of practice was my secret!

Take care!
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Old 05-16-2006, 04:08 PM
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Default RE: Speed beginner, few Q's?

you could install a few head shims on your webras to "decompress" them a tad to run on the higher nitro fuel. European engines are generally designed to run on low nitro, because its really expensive/illegal to get there.
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Old 05-17-2006, 06:29 PM
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Default RE: Speed beginner, few Q's?

It's a few € diffrence between 15% and 5% fuel but I hardly think it's illegal with added nitro in the fuel.
Anyway, I picked up a Byron 5% at my hobbyshop, spiked it with some castor and will use it to break in my Webras.
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