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

all diamond dust post

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Old 10-27-2006, 03:16 PM
  #1  
willflyforfood
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Default all diamond dust post

Hey guys a buddy of mine and I are about to build a pair of diamond dusts, and I was hoping whoever had one could postsome pics and give us any tips or mods we may need for building. I believe he has rear exhaust MVVS .46 and I have an MVVS Q-500 .40 that I am converting to rear exhaust and both with tuned piped of course. I would like to get as many pictures and help up as I can thanks a lot.
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Old 10-27-2006, 04:58 PM
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WD
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Default RE: all diamond dust post

Here is a link to a thread that I posted that might help.

http://www.rcuniverse.com/forum/m_40...tm.htm#4071055
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Old 10-27-2006, 06:25 PM
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combatpigg
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Default RE: all diamond dust post

I think it is important to glass both sides of the fins after you've shaped them to a knifes' edge. Use hard balsa 1.25" aileron stock for your elevons. I like to use those Rocket City control horns, which are threaded posts that get clamped to the elevons. Set the pivot point at about 1.125"-1.250" above the flap, this will give your servos good mechanical advantage for fine control. I think a cowled front end is worth the effort, built over a one shot foam plug. I use medium CA instead of epoxy for quicker results.
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Old 10-27-2006, 07:30 PM
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Default RE: all diamond dust post

I have had problems with the 4x40 push rod wires, lots of vibration and noise. For push rods I am now using 3/16 carbon fiber tubes and titanium ends that are available from Central Hobbies. You don't need to rout these through the wire tie that is attached to the fin.
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Old 10-28-2006, 12:09 AM
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Default RE: all diamond dust post

Those are both great ideas that I was already wondering about, I like to really shave things down. And I will look into the carbon fiber pushrods. CP I have a drawing I need to send to you sometime of a plane that I designed just for this engine that you might like, it is much like the " speed cup " planes. And when you are making the one shot cowling you said you are just using CA to do it? How do you keep from melting the foam? Or do you just use foam safe? A cowling was the first thing that I thought I thought of when I knew I may be getting one, thats a good idea.
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Old 10-28-2006, 12:57 AM
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Default RE: all diamond dust post

WFFF, I use blue foam, pink works OK too [for plugs]. Then mask it off with bits of packing tape. this is painstaking, but it goes pretty fast. The cowl in many cases is laid up right there stuck to the firewall. The firewall and forward part of the fuselage get masked off with clear packing tape,also. The foam is stuck to the firewall with 3M77. I like the cowl to overlap the fuselage on sport models, but on a serious speed plane, you would want it flush with the fuselage. Anyway, the next step is to cut out lots of patches of cloth, I use the weight that they carry at the hardware store, fairly heavy stuff, 3 or 4 ozs? lightly mist the cloth pieces with 3M77, then start applying the cloth to the plug, with slight overlapping. Once you get a complete first layer stuck to the plug, then put a latex glove finger on and work medium CA into the cloth, ZipKick it, knock down the high spots with sandpaper, then go for another layer. It will take 3 or 4 layers to get a sturdy cowl. It doesn't take that much glue, but it usually does a burn job on the sinuses. You can peel the foam out of the finished part with a wood chisel, just chew out the foam in the center of the plug, once the plug has been weakened enough, then you can peel it away from the fiberglass part. You will need to paint the cowl with fuel proof paint because CA is not fuelproof. To fill the weave, you can laminate a lighter weight of cloth on, or just sand the heavy weave and smear it with Bondo or glazing compound. Have fun!
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Old 10-28-2006, 07:12 AM
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Default RE: all diamond dust post

Here's a picture of mine. K&B powered. It has a rear intake and rear exhaust so I built up the nose a little behind the spinner to 'blend' it into the airframe. Just for looks more than anything else.

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Old 10-28-2006, 07:13 AM
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Default RE: all diamond dust post

When you've built your first dust and flown it, you'll want a little brother for it! [8D]

The lil guy is teedee .09 powered.
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Old 10-28-2006, 09:56 AM
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Default RE: all diamond dust post

Thanks CP that makes sense and I may give it a shot. I have a couple of other planes that it may be good to do that on as well. Smchale your dust looks nice and I like the little one. I have an ops .21 thats perfect for that but its for the other speed plane. Both of them look great though thanks for the pics. Will I be able to run a straight header pipe like that or did you put in a bladder tank?
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Old 10-28-2006, 11:36 AM
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Default RE: all diamond dust post

You'll have to mock up a side view of your engine and pipe to determine tank clearance. the plane might end up needing a belly to provide room.
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Old 10-28-2006, 11:08 PM
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Default RE: all diamond dust post

Here's a link to some mods that I have done. I used carbon fiber control rods and carbon fiber sandwiched between each fin to stiffen them up. Also made an access panel for the servos and radio. Making the wing thinner also reduces drag.

http://www.rcuniverse.com/forum/m_4883723/tm.htm
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Old 10-30-2006, 10:51 PM
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Default RE: all diamond dust post

Thanks that helps. Why were you only getting 115 out of the GRRT though? For some reason that doesn't sound right at all. There is a guy at our field that had dust with that same engine, and it was well in the 160 range very very easily if not more. I have the MVVS q-500 thats never been run, and I am turning it to rear exhaust and I am expecting some impressive results. I thought an 8x8 would be an appropriate place to start looking for good results am I way off here?
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Old 10-30-2006, 11:38 PM
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Default RE: all diamond dust post

The 8x8 matches up well with this plane. I spent some time last summer clocking mine with a variety of props, and the 8x8 was right in there for all around flyability, launchability and speed. The 8x8 allows nearly a vertical launch if the plane isn't overbuilt and if you've got an engine there that can pull it's own weight. The best times were with the 7.2x8.6 [launched at 24,000]. If the engine doesn't respond with this kind of rpm when you go down in diameter, then you're better off playing with more of a sport prop, like a 9x6 or 9x7. It sounds like your combo will crank the 8x8 in style, though.
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Old 10-30-2006, 11:46 PM
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Default RE: all diamond dust post

I was thinking (and hoping) I was on the right track. This engine is not of course a nelson but by-golly it's pretty dang stout. I am looking to get into the 24,000 range I think that is feasable with a little tweaking.
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Old 10-30-2006, 11:49 PM
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Default RE: all diamond dust post

I was also thinking it would be a lot of fun also to make a cowling, that would actully be a " fuselage" for this plane, that I could easily remove and put back on just to see how much of a real difference I can make by cleaning up all of the stuff hangin out.
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Old 10-31-2006, 01:09 AM
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Default RE: all diamond dust post

The mod that paid the most dividends for me with a K&B 6.5 was to cut the piston skirt off on the bypass side. This lightens the piston and unshrouds the intake ports in the case. The piston also had some meat removed inside the pin boss area. I knife edged the rod, also. The engine needed to be balanced afterwards so I did a trial and error balance job by grinding a couple of shallow divots in the counterweight. It took 2 tries to get the engine running smooth. I also ditched the carb, made a venturi and went with a high pressure bladder.
The cowl is worth the effort, I have seen a cowl make the difference between unloading mass rpm and having the plane act like it has a speed brake deployed.
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Old 10-31-2006, 01:52 AM
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Default RE: all diamond dust post

I was contemplating the venturi as well for a couple of reasons. For one I didn't get this engine to fly it at half throttle, it's strictly for speed, and it will also make it much easier to cowl the front end as well. That is a quick mod that should spark some modest improvement. Before breaking this engine in, do you think 24,000 is too much to ask from it? I dont think it will be a problem, it's just that I always break them in according to what RPM the engine will spend it's time and dont know these engines well.
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Old 10-31-2006, 08:05 PM
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Default RE: all diamond dust post

WFFF, I don't know anything about the MVVS. If it has good bearings and well made parts it should respond well to taking weight off the piston and rod. That will increase the engines' redline, less weight churning around at the speed of sound.
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Old 10-31-2006, 08:51 PM
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Default RE: all diamond dust post

I seriously doubt you will be seeing 24K from an MVVS Q500 with any flyable prop (without some serious engine modding that is). MVVS uses very good bearings though. A few guys at our club are using them in "entry-level" Q500 racing, and they are just that: entry level engines.

One guy is using a 20 or so year old "tweaked" Webra .40 with Nelson Q500 muffler and it is a hell of a lot stronger than the MVVS's. But on the other hand, that guy used to fly F3D and made it to a 7th place at the world champs in 1993... so I think he knows a thing or two about setting up an engine...
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Old 11-01-2006, 11:24 AM
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Default RE: all diamond dust post

Well the MVVS engines that both of us wil be running are pretty hot, their not just your stock sport engines. On top of that there will be mods made to do some performance upgrades. From what I have been told and seen firsthand these engines respond great to enhancements, it really is a good base for a high performance engine that is made very well. The only thing is I'm having trouble trying to decide if I should do everything I want to it before I even break it in or just take it easy for a while and slowly tweak on it to see improvements. I saw a guy that took a pretty hot MVVS .26 and turn it into an absolute monster, and there is a GRRT at the field that packs about as much punch as you are gonna get without getting into the nelson/jett arena so I know it can be done. I'm not saying this as to gloat, just mentioning that I think they have a lot of potential due to the quality of the engine. Also I'd like to see some more videos of some of the Dusts if you guys know where any are, I am having a hard time finding them.
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Old 11-01-2006, 07:27 PM
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Default RE: all diamond dust post

WFFF, if you break in an engine, then take it completely apart...you will have disturbed the piston liner wear pattern no matter how well you think you can put it back together. If you already know what needs to be done internally, no better time to do it than when the engine is brand new.
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Old 11-02-2006, 12:00 AM
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Default RE: all diamond dust post

Yeah thats the only thing that would keep me from not doing it at first. I may just go ahead and do it all who knows. I would like to know what kind of improvement I could make, thats why I wanted to wait but I doubt it's worth breaking the alignment.
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Old 11-02-2006, 11:38 AM
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Default RE: all diamond dust post

This is the most impressive Diamond Dust video I've ever seen:


http://media.putfile.com/Modified-Diamond-Dust
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Old 11-02-2006, 01:26 PM
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Default RE: all diamond dust post


ORIGINAL: smchale

Here's a picture of mine. K&B powered. It has a rear intake and rear exhaust so I built up the nose a little behind the spinner to 'blend' it into the airframe. Just for looks more than anything else.

smchale

What K&B is that? I have a 6.5 Rear Exhaust I am planning to put into a DD style delta.
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Old 11-02-2006, 01:29 PM
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Default RE: all diamond dust post

Yes, that's the 6.5 version. Seemed to like running wide open...or not at all. I guess I'm spoiled with the reliability of my Jett FIRE 50 that idles as well as runs flat out.
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