freakingfast

My Feedback: (3)

That leading edge came with the "clipped wing" version Diamond Dust. I hunted it down and it turns out to be 1/8 doll house roof cap. Hold off till I test fly her and I'll let you know if it spoils the air flow (stalls) in hard turns. I’ve been sick today and there is very turbulent wind here today so tomorrow looks good for flight. Going to test run the engine on the plane and rattle the neighbors a bit now.

freakingfast

My Feedback: (3)

Glad I tested it. The throttle servo was reversed (dummy), wouldn’t start, the plug finally died, the prop wasn’t oriented horizontal. Got a blister, the coupling that I hold it by is too short. The needle needed to be opened another ½ turn (a tad rich, off peak) for a total of two turns out, I guess the bubble-less clunk adds a bit of restriction but the needle still has a nice definite peak. I held it lightly several ways and saw no bubbles with a ¼ tank, so far- so good, at least on the ground.

Dang that thing pulls hard, so temped to let it go. Soon!

Mike Connor

My Feedback: (5)

Deltas fly by there own set of rules. My experience says the sharp leading edge will not have a negative effect.

freakingfast

My Feedback: (3)

[quote]ORIGINAL: Mike Connor


You are so right!

freakingfast

My Feedback: (3)

Success!

That thing is fastest thing I’ve flown. Eyeball speed looked to be about 190+ and I think there’s more to be found. It was realy gusty, so much so that I had to hold the plane down on the work table so it wouldn’t blow away. I launched at a lower angle than normal so it won’t end up right over my head. It was a bit twitchy on the roll axis at takeoff so I’ll reduce my rates and remove the all the expo that I use for launch. Trim was close, two clicks up and one right. I set the timer at 2 minutes 45 seconds which was perfect for an 8 oz. tank, which left about enough fuel left for one landing go around. The smoke trail was nice and constant and the engine ran flawlessly. I pulled the plug and the element was still shinny, centered and even. The clipped wing DD flew better than I had hoped, smooth high speed low passes, and predicable turns. I tried some abrupt turns and “walls” and not a hint of high speed stall.
My biggest surprise was the roll rate, faster than the standard DD and about twice that of the Outlaw! What a buzz saw! The landing was perfect, with the strong head wind it ran on the landing skids only about 10 feet. I few it once, the only other pilot left, my cap blew off my head and I had to chase my fuel jug so I thought to myself this is nuts, I’m going home in one piece.
The prop may be too much; it didn’t unload much, maybe 1 K or so. I was a bit busy at the time to realy listen. It was probably running about 22.5K at best and I’d like to see it at about 24 in flight. Next time out I may want to try a 8.8 X 9.5 and maybe a 8.8 X 9.25.

A very good day!

Mike Connor

My Feedback: (5)

Congratulations on the maiden. Seems you could cut down the landing skids by 50% or more. They have to be a lot of drag. Doppler should prove very interesting when you get everything right.

freakingfast

My Feedback: (3)

Yes they do have lot of drag. The rear ones are held in place with set screws and the front is attached to the motor mount if I ever find a nice grass field to land on I'll take them off.

I just got back home and got another flight in. The wind was gone The good news is I got it on video, the club president had his camera and he said he would post it soon on YouTube. Ill let you know the link later. The bad news is, it high speed stalled and it realy shook me up which lead to my worst landing ever with a delta (400+ flights) all caught in living color.
The engine linkage had slipped a bit and I could not shut the engine off right away, I was about to abort than the darned thing quit so I landed hot slid off the end of the runway and the thick weeds snagged and spun it. The only damage was some stress marks near the tip of the prop so that prop is toast.

It took a dive and a quick full pull to make it happen and I may have not pulled the stick strait back. It was the most violet event I have ever witnessed. It totally lost all laminar air flow. Everyone thought I did it on purpose (because of my Outlaw flying style). The Diamond Dust does not recover like an Outlaw. I barely got the DD out of a wobbly flat spin, very mushy, slow to recover. I will test this again much higher and further out.

I did this once to a Whiplash and no matter what I did, it was locked in a flat spin to the ground.

Still a good day!

combatpigg

My Feedback: (3)

Congratulations! Sounds like your report card for being ready is way up there. This kind of duty has to be a walk in the park for that engine compared with being inside a DF torture chamber.

freakingfast

My Feedback: (3)

Here's the video link. I don't know if any Doppler info can be had from it, I noticed that the same guy that asked the same question twice "is there a pump in that" when I was on final had his car radio blaring in the background. It looks like Richard edited out the first few minutes because of it was out of focus. Note the reason why you don’t land in the grass around here.

http://www.youtube.com/watch?v=fVp39wJMeCM

Mike Connor

My Feedback: (5)

The only pass that gave decent Doppler info was at the 20 second mark (down wind/no wind?). There may have been better passes and better flights but here is what I got.
158 mph
20,700 rpm
I like my Doppler readings to be backed up by other speed measuring methods but this is what we have for now. Not too bad considering everything.

freakingfast

My Feedback: (3)

That's great info Mike! Thanks a million
I did'nt think it unloaded much, I will be dropping down on pitch. The engine's peak hp is at 23K and I'd like to put it at or a little over that.

Thanks for the quick info Mike! [sm=thumbup.gif]

Mike Connor

My Feedback: (5)

The right prop with a good tune and no skids and that thing will cook. Nice job. [sm=thumbup.gif]

freakingfast

My Feedback: (3)

I can shorten the skids by half and perhaps teardrop shape whats left. If I loose them, there will be one fast flight followed by repair time[&o].
Options. #1 change prop. #2 shorten header 7/16" for peak at 24K but this means cutting closer to both the bend on the header AND the taper on the pipe.
#4 try a nitro tuned pipe #3 up the nitro from 30% to 60%. The down side for this is A: shim the head. B: less glow plug life C: less engine life D: less run time. E: fuel cost.

combatpigg

My Feedback: (3)

FF, the difference in actual speed won't be that much if you go nuts with the nitro. My first instinct with props is to whittle on the prop that you want to see work until you see the plane slow down, then move on to plan B prop, etc. I haven't seen any world class speed props in person, but get the impression that the blades are thinner than stock APC carbon jobs.

bob27s

My Feedback: (19)

just change one thing at a time..... or you will never understand how the change affects performance.

The 8.8x9.75 prop has not demonstrated very good speed in the air for the Q-500 aircraft. Try the 8.8x9 and 8.8x9.25 props. Do not be that concerned with the ground rpm ... leave the pipe at the same length to start with.

The project looks great.... im pleased to hear it is performing well !

combatpigg

My Feedback: (3)

The wire skids look innocent, but they always make me remember an article that was published in Hot Rod Magazine about 60 years ago when comparing the drag of different class Bonneville cars. I don't remember the specifics but the numbers were shocking between the classic streamliners and the chopped top coupes with open wheels. Just duct taping the seams on the body panels made a difference. Back then HP was very limited and they were more in tune with what a guy on a limited budget could do with holesaws and a cutting torch.
FF, I don't know about your field, but up here I drive around in circles in my Jeep for awhile to beat down the grass and mole hills to make a half decent landing strip. I've never done it, but have considered staking down jumbo tarps when the field is soggy also.

Mike Connor

My Feedback: (5)

My fun fly delta was very noticeably faster when I removed the 1/8" piano wire gear. NASA says the round shape is not good for drag and it gets worse as the speed increases. It seems like you could get away with short 1" skids that would help some.

mmattockx

"Not good" is putting it politely.

The best choice would be skids that look like small vertical stabilizers, airfoiled and tapered to a thin TE. Even fins made from flat plate 1/8" thick would be lower drag than round wires.

You could easily test the idea by making some simple balsa fairings and taping them to the skids, to streamline the back side of the wire. Something similar to the LG fairings that Goldberg use on their Ultimate bipe and Extra 300 models would work OK.


Mark

med601

My Feedback: (5)

Hey Guys,

I've been flying diamond dust's for about 12 years now. I only have flown them with 0S 32SX / TT36 pro with mouse can mufflers.
I now want to buid one that will go faster. I'm looking for the right engine and pipe combo.Ive been looking at a K&B 6.5, 0S 46 DF and I just bought on Ebay a used Jett 46 sport without a muffler ($105). I don't want to spend a fortune. What do ya think?

Lomcevak Duck

My Feedback: (14)

I flew a Dust with an OS .32SX for a few years, one of my all time favorite planes.

That Jett ought to fly it nicely.

bob27s

My Feedback: (19)

Keep in mind the Sport Jett 46 is not going to run its best without the Jett muffler that is designed for it. You can use a full sized pipe on it - if it is set up properly.

med601

My Feedback: (5)

Bob,
will a header and tuned pipe for a 0S 46FX fit the Jett 46?

bob27s

My Feedback: (19)

No, the header will not mount. Muffler bolt pattern matchs a ST 40-50 - wider than the OS46.

The pipe would be the same.

Looks like you have somewhat of a collectors item there

victorzamora

I've been following this thread for a while...I've been wondering if you've heard of the anti-bubble trick spreading around RCU. Use a bit of armorall in it and it won't bubble.

bob27s

My Feedback: (19)

The armorall technique has been around for quite a few years. It works to a limited extent, but is only a bandaid for the problem and does not prevent air ingestion from a low fuel condition.