robert92679

Here's a video of some fun on a Sunday afternoon:

http://www.gholamipour.com/videos/pl...peedplanes.wmv

It's a 12 Mb download.

One of the guys at our club likes to chronicle the activities on video, so I can't take credit for the pictures. But I can take credit for flying the Diamond Dust! The Magnum clearly had the speed advantage, but it was still a bunch of fun.

cobratraxxas69

My Feedback: (31)

Cool video Robert...what engines do you guys have in your planes?

-Mike

Rudeboy

You gotta lean that West out a little more... sounds a bit rich...

robert92679

The Magnum is running the Weston motor that comes with the combo kit, with an APC 8x8 I believe. My Dust is a YS 45 rear exhaust running a 9x8.5 APC.

Rudeboy: Thanks for the tuning advice. I'll pass it along to my buddy, but he's already having a problem blowing plugs. Going leaner would only make it worse. We're thinking maybe a head shim?

ddavidson

Do you know what the Magnum weighs?

It also looked like the glide on the Magnum was pretty short. Any coments?
Dick

Rudeboy

Do not shim the head... I went that route too initially, and it only made things worse. When you lower the compression you will have to lean it even further to get it to run. And like you noticed, lean means hot... means blowing plugs.
When I shimmed mine, I had to run it so lean it almost cleared the purple anodising off the combustion chamber... Needless to say it didn't last long that way.
If the rpms aren't up there, and you haven't cut at least one inch off your header, then that's what you have to do.
The pipe lenghth the way it comes from the factory is set WAY too long for running APC 8x8 props. I think it's more set for 9x6 or 9x7 props.
Also, what fuel is he using? I noticed the West likes nitro. While 10% is advised in the paperwork and works fine, 15% or even 20% work better.

rgscomputers

That video was awesome!!!


Do you guys have any estimate as to the speed of those two? Mine seems like it may be a little quicker but I have no idea how fast it is.

wilkigmc

Cool Vid! I've found the best prop for the Magnum on my westy is an APC 8x10 on 15% nitro without modifying the pipe.

bob27s

My Feedback: (19)

Nice video ! And a nice display.

On the blown plug issue..... if I may....

It was clear from the video that your buddy flew the plane out of fuel. When watching the clip, you can see that from launch and for most of the flight the MAG had a nice smoke trail. It was a touch rich, but running nicely. Personally I would keep it at that mixture. On his last low pass, you could hear the rpm pick up and see the exhaust trail was gone. He clearly sets a bit rich initially to deal with the engine leaning out at the end of the flight.

Over the last minute or so, the engine was drawing air bubbles from the tank, and going lean. Running the tank dry certainly meant picking up a great deal of air in the feed line. The clunk bounces around in and out of the fuel, and there is likely at least a bit of fuel foam in there complicating things. Flying dry forced the engine super lean at least for the last 30 seconds or so. That will blow a plug in a heart beat. Over time it will toast a piston fit.

Plugs blow for basically one reason - a lean run. If the engine has a tendency to blow plugs, it is doing it at the end of the flight at that point where it begins getting air in the system.

How to avoid a blown plug .....
1) time the flight so the engine is always shut down well before the tank is dry - you do not want to run much below 1/3 of a tank.

2) install a bubble-free fuel tank. Tetra or a Jett tank. With those, foam-bubbles-air are not an issue at any point ... mixture stays consistant all the way to the last drop. If you fly out of fuel, the engine quits rapidly rather than leaning gradually and getting hot.

I hope this is helpful
Bob

robert92679

Thank you, Bob, for taking the time to explain that. As usual, I believe your assessment is right on the money. I'll pass that along to my buddy with the Magnum.

I don't know the weight of the Magnum, but it is basically stock. The glide path was a bit short this time because Mike may have pulled up too much when the plane went deadstick, bleeding off too much speed. The glide is usually better than in the video, but I don't think it's ever really long.

As to the speed, we don't have a radar on either of them, but the consensus is that they are probably in the 125-150 mph range. Certainly fast enough to get the old blood pumping by the end of the flight! Also, please don't flame me on my estimate of the speed; it is just that, an estimate.

Thank you all for the comments and suggestions.

Robert
Revver Brother #76

bob27s

My Feedback: (19)

Glad to be of help. You are probably pretty close on the speed

One thing I noted from your user info and that video....... you really do fly in a canyon

mpriestley

My Feedback: (1)

Hey guys,

this is mike, from the video. didn't know my ears were burning...

Wanted to chime in and thank you guys for the comments about the blown plugs. Bob, your explanation sounds very good to me... I have modified the pipe (cut it) and am running apc 8x8... os 8 plugs and I normally run her a bit more lean with out problem... get a bit more speed but you know how these planes are... finicky... not a plane that you can just set the the needle and not worry about it for a couple of weeks, you really have to fine tune it each day you fly em...

and yes your right, it makes sense to have some self control and shut her down before running out of gas... I tell you though, a dead stick at our field will get anyone jazzed... not sure if you noticed but I just made it over a power line before touching down... we have power lines that run down the canyon that you have to avoid along with a strong creek (not visible but only a stones throw away, and on the landing aproach. It is basically not a good thing if you dont make it to the runway. but a great field it is... truly!!!

anyway thank you for the advise,

mike,