RCU Forums - Magnum

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- - Magnum (https://www.rcuniverse.com/forum/extreme-speed-prop-planes-104/11543579-magnum.html)

Came in today, I will be up all night! http://www.rcuniverse.com/forum/js/f...eeth_smile.gifPS I got 2 just in case the first flight dosn't go well LOL

Welcome to the game!
What engine are you putting up front?
:D

I was thinking Jett 50

Nobody around here ever brings cool stuff like that out to fly.
This area is basically ARFTRAINERINSIDELOOPONLYVILLE.
I'm all excited to see this combo of yours doing it's thing...!!

Get you some 9x8 apc props and bring it on.

I think I used 9x7 for the first flight till I got the cg where I wanted after that I have run as close to a 9 square prop as possible.

See you at the Rally!:D

PHASE,

I have a Jett .50 & muffler on mine, had to add some tail weight.
I Put it on the tail end of the fuse AND put a square battery behind the elevator servo!
If you go with a headder and pipe less/no tail weight required.
Also I used a base loaded mini whip antenna.
Additional: Use a trim solvent to seal the edges, the "carbon fibre" blew off the wings on mine.

Bob

Thanks for the heads up airfarme is together going outside to put the engine on the stand and run it at 17,000 for awhile. Will let you know how it balances. Daniel

Sounds like a real nice setup good luck with it!

where can you get the magnum at? i have a webra speed 50gt that would be a good candidate for it,

I think www.SMTDISTRIBUTING.com carries them.Daniel you need to hurry bout got my mini-magnum together with a Novarossi R26CR ready.

Can't wait to get one or two of the Novarossi's, I may have a few things to hang them on

smtdistributing.com has them,got mine yesterday,fitting a novarossi cr57 to it ,looking for 200 mph hold -on

If SMT flys what they sell, couldn't they provide some actual, real life performance figures for those speed engines..?
Maybe they do and I didn't see any.?

I have spoke with SMT over the phone a few times, they are going to a event in GA shortly and will have the engines on stands to do side by side comparisons to other brand speed engines ( As all of you know I'm new to the speed bug don't know the tech name of the devise used to measure trust ) I'm going to try a few of them out although I may not be the most qualified to give test result I will be honesty about myresults good or bad

Static thrust measurements for speed engines aren't real ......valuable.
If they are selling a .45-55 engine with a tuned pipe I'd like to know what size props @ what rpm it runs .
Speed engines with high exhaust timing have a very narrow range of props they can turn at resonance...[AKA "hitting the pipe"]. The properly matched load will have an explosive jump in rpm, but high timing sacrifices torque until the revs are able to reach the magic rpm level that the exhaust is tuned for. With too much load [such as with typical sport props] the magic isn't going to happen.
Sport engines with low to medium exhaust timing can produce more "dynamic compression" [pushing force against the load] so they have a much broader range of props they can turn reasonably well. These engines have broader appeal to the sport flyers and are still capable of impressive speed on the right plane.
With the high timed speed engines there are way fewer "right planes" to match them up with.
It'll be interesting to see what Novarossi has cooking for such low prices....??

Were did you buy the magnum plane

Quote:

ORIGINAL: phase5

I have spoke with SMT over the phone a few times, they are going to a event in GA shortly and will have the engines on stands to do side by side comparisons to other brand speed engines ( As all of you know I'm new to the speed bug don't know the tech name of the devise used to measure trust ) I'm going to try a few of them out although I may not be the most qualified to give test result I will be honesty about my results good or bad

Not to repeat what CP said, but static thrust measurements for speed applications are totally meaningless. The only thing that matters is how much thrust the prop produces at flight speed. The angle of attack of a propellor at any specific rpm varies with the forward speed, therefore the efficiency varies throughout the flight regime. A small high pitch prop is running at or near stalled condition on the test stand, stirring a lot of air in meaningless directions. The prop giving the highest static thrust could easily be the worst choice - to exaggerate the example, think 11-4 versus 9-8.

How would you compare a .50 that is tuned for peak horsepower at 17k rpm, to one tuned for peak horsepower at 21k? Would you put the same prop on them, for example a 10-6, and compare? The higher timed engine might spin it more slowly than the other - but, prop it for peak rpm and it may develop more power than the lower timed engine.

Speed comes from horsepower - not torque alone, not rpm alone - the product of the two, PLUS - a prop matched to the engine and appropriate for the airframe at the same time. Put 200hp in a Honda Civic and you can gear it for 150mph, but put 200hp in a pickup truck and you can't run the same gearing. But they will both do the same amount of work in the same time.

A good example might be an OS .50-whatever to a West .50 - bolt an 11-6 to each and see what happens.. my guess is the OS wins the static thrust battle. So which one can fly your airplane faster..? Which one has the highest peak horsepower?

You can make a somewhat meaningful comparison between engines designed for similar operating rpm by running a common prop on each. In that case, rpm is the litmus test.

I'm not pooh-poohing the test stand comparison, but I am suggesting that you be thoughtful about how you evaluate. Honest as they may be, there are many ways to set up a side-by-side comparison to make your products look good. That said, I am quite sure they are great running, high quality engines. Will be fun to see the demo.

Quote:

ORIGINAL: heytex

Were did you buy the magnum plane

http://www.smtdistributing.com/AIRPL...TS-arf_c93.htm

Wow......I wasn't aware that these were still around.....as it makes me miss mine. I sold it on a whim and have regretted it ever since. They are great flying planes and are very easy to get fast.

This is funny, I was thinking of yanking mine out of the closet today and putting it together, when I stumbled on this thread.

I have steadily been working on the Vicman version re-build. I'm in the covering stage right now.
Actually I'm working on the Mag and an older Kangke F-20:eek:

I might get another. My last Magnum flew off into the sunset along with a ST X-40....

Getting ready to test fly a Magnum with evolution .52.& macs pipe muffler. I am confused about the C.G. the booklet sez to balance from wing root. Do they mean to balance from leading edge of wing root? Anybody got an answer.

Yes they mean from the leading edge at the wing root. Check with Vic or Smokin they could give you some tips about the CG of the Mags, they are both familiar with them, I recall something about an error in some of the manuals as far as the COG.

The factory CG range goes from Extremely nose heavy to really nose heavy to nose heavy. Many people find joy at around 160-165mm from the LE at the root, but there are others who have gone up to 190-195mm and report everything is peachy. Start towards the rear of the factory range - it is not a "rearward CG".

iron eagel is bang on with how it is measured - always at the root where it meets the fuselage.