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Diamond Dust in air and GRRT runs great after rebuild.

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

Diamond Dust in air and GRRT runs great after rebuild.

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Old 07-13-2003, 12:40 AM
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FlooredCOBRA
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Default Diamond Dust in air and GRRT runs great after rebuild.

I finally got my piston sleeve and rod in from Morris Hobbies. My GRRT been a sitting duck until today. I finally got to crank it up and hear the ole sound of the pipe popping.

I got it broke in pretty good and decided to fly around rich and get the hang of going fast again. I cranked up hit WOT but was still rich enough so it ran just under pipe. Had a nice smoke trail behind it. I aimed up and launched and it took off perfectly.

I flew around to get the trim set and flew around at about 1/4 throttle. Just trying to still be easy on the new working parts. It reacted what seemed to be better than when I first bought it and flew it. It had instant throttle response never loaded up. I was tickled pink by then. I flew around some more going up to half throttle for a little then back to 1/4 then back. It finally ran out of fuel then I landed.

Next flight I left it still rich and launched into air. I flew around some more from 14/ to 1/2 some. About mid flight I was on a straight and hit it WOT for a second. It revved up and stayed under pipe still. I I tried again and this time it hit up on pipe. At this time it has been so long I forgot what it was like to haul in the air. The pipe kicked in and it looked like it was on a rubber band and launching again. I made a pass and back out again. Flew a little more and hit it again. Pipe kicked in and it took off but I didn't hold there but for about 2 seconds or so. I was still trying to get used to it. Finally it ran out and I landed.

3rd flight went good and again engine running good. At this time my buddy got to field and was excited to see it run after all the time. I made a few slow passes then kicked it for a second. He was cracking up at this time and was saying " I got to get one of those!" I was trying to explain I was being easy and to wait one more flight then I will kick it in the full flight. I made my turn to come across field low and all of a sudden I had no up or down on one of the elevons. Well it being a delta natural when you pull it up it will roll with one out. It rolled into the ditch where high weeds were and I heard a thud.

At this time I was sick to my stomach and pissed that there was a failure and not me that made it crash. I don't mind me being stupid and crashing but not when it is a failure inside somewhere.

I walked over and it was in the ground. I pulled it out of the dirt and one of the leading edge rodes was broke in 2 spots. Everything else was okay, well besides prop but thats okay. The engine was okay that goodness! That was my main concern rather than the plane. Luckily I wasn't going WOT when it hit or it would have been a mess.

So now here I sit with a kicking running engine and a plane to fix..... Not a good day. All I got today was a tease and never got a chance to really move out. But good thing is it wont take much time to fix. I just need to find a rod the same size thats in there to replace with.

The reason why it lost control was due to thew foam padding on receiver wadding up under servo arm and pulling the whole receiver in front of servo arm. It totally blocked the throw of my horn and this little stupid thing is what made me crash today.... Oh well things happen. Today was a good day and bad day at the same time. Engine ran good and me over looking insides made me crash.

Well things happen. Luckily I wasn't WOT and it did this into pits or hit something. So in a way I was lucky. So now back to fixing and hopefully I will be back in air this week.

Main thing is the GRRT hauls!!!!
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Old 07-13-2003, 12:41 AM
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Default Diamond Dust in air and GRRT runs great after rebuild.

sorry for such a long drawn out story.
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Old 07-14-2003, 03:21 AM
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Default Diamond Dust in air and GRRT runs great after rebuild.

sorry to hear about the crash. I was under the impression the GRRT didn't have a throttle, I am incorrect I assume?
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Old 07-14-2003, 03:35 AM
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Default Diamond Dust in air and GRRT runs great after rebuild.

It don't come with one, just a Venturi. The carb has to be purchased separately.

Well one thing I did fix my Dust and just need to recover it now. But I found I had a bad servo that works but with the slightest load it wont move. I can barley touch it and it will stay flat. Well now I know what caused it for sure.
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Old 07-14-2003, 10:02 AM
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Default Diamond Dust in air and GRRT runs great after rebuild.

Nice to hear these nice stories about the GRRT, Can't wait to lauch mine
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Old 07-14-2003, 06:21 PM
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Default Diamond Dust in air and GRRT runs great after rebuild.

well after I get it covered and servo swapped out I am going to post a video. Just not to sure how to doit but worth a try.
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Old 07-22-2003, 02:02 AM
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Default Diamond Dust in air and GRRT runs great after rebuild.

Sorry to hear about that, gravity always seems to win.

My grrt on my dd failed this weekend. I had flown it about five times with different props trying to find the "sweet" one. I made a couple of laps around the field, then the engine rpm started rising and falling several times with a click, then dead silence. Glided back in with a normal landing. Appearently when the engine clicked, there was enough force to unscrew the prop nut and prop to force both of them off. The engine now turns about 180 deg and stops.
Meanwhile, back to the repair shop.

As far as servos go, I started using the Hitec 5475 digital on the dd and it works great !
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Old 07-22-2003, 02:27 AM
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Default Diamond Dust in air and GRRT runs great after rebuild.

Ouch! I know the feeling.

I am curious as to what happened to it. I know one thing if its the rod or sleeve you have to buy all 3 together. The rod sleeve and piston all comes matched. It is not very expensive just a pain to have to wait for an order to come in.

I been flying mine like crazy well was until the covering on bottom burst open.

As for props I have been messing around with a bunch of them just seeing which one works the best. So far I have tried a 8 X 6, 8 X 7, 7.2 X 8.6, 7.4 X 8.0 .

I like the way the 8 X 6-7 launch better. As for speed I really cant tell how fast it is going. As for the 7.2 and 7.4 's It takes about a second longer to start grabbing. It pulls out okay but not like the others.

Wish I knew how fast it was going so I could compare between the props. It all pretty much looks the same to me when I fly with them. I kind of get zoned in on the plane and cant really tell the speed or haw fast its going past things. Everyone else swears its hauling even if I am putting around. To bad we don't have any other Dusts with GRRT's flying at our club. I would like to see one fly also instead of just me flying it.

Also what props did you try out and what kind of numbers were you getting on ground?
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Old 07-22-2003, 02:56 AM
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Default Diamond Dust in air and GRRT runs great after rebuild.

I havn't looked at the engine yet to know exactly what failed. When I said 5 flights eariler, I meant for that day. About 50 total. I'm sending it back to morris to let them look at it.

Most of the props I try give me 22k-23k with coolpower 5%. I modified a prop to make it a 7-8 and it started making the dd flutter! The 7.2-8.6 flew a little slower. I have a radar gun, but it is very hard to pick up a stealth! I'm looking at the eagletree recorder and may try one of those to measure speed.

We also took some video where I'll try to capture the sound and run it through the sceptrogram program for some speed/rpm estimates.
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Old 07-22-2003, 03:06 AM
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Default Diamond Dust in air and GRRT runs great after rebuild.

I have one of the Eagletree recorders...but they only go to 150 MPH. The guy says they can be made to go higher with a simple resistor swap, but I have asked him several times to tell me which resistors and what value...no answer.

I'd like to use it, but it just sets there in the box.
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Old 07-23-2003, 01:45 PM
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Default chuckauger

I assume the components are surface mount (very small!).

I have never seen one of these but this is how I would approach it....
I would look around the pressure sensor and trace leads that connect to any resistor. Try connecting a voltmeter across the resistor(s) any put a very low pressure on the pitot tube and look for variations in the voltage across the resistor(s) until you can find the one that varies with air pressure. Once that is found, measure the value of the resistor (may have to remove from circuit to get an accurate value) or get out the magnifying glass and look for a value. When that value is known, you should be able to vary it by a percentage to increase the span of the measurement.

Keep in mind I've never seen one but this is how I'd hack it. I'm interested in one if it's possible to increase the speed limit.
Let me know if you can do this.
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Old 07-23-2003, 03:01 PM
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Default Diamond Dust in air and GRRT runs great after rebuild.

I have no problem with the electronics part of it..the only thing that would set me back would be getting an accurate calibration after changing the values. I had hoped EagleTree would have some sort of calibration (they made this one to 150MPH) and could give the actual, accurate resistor values.

Finding the correct resistor...no problem. Changing the value..no problem. Getting the correct value to be calibrated and accurate to 250MPH..priceless, and as I have no way of producing an accurate 250MPH breeze, I'm afraid that is where it ends.
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Old 07-23-2003, 03:52 PM
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Default Diamond Dust in air and GRRT runs great after rebuild.

You could consider building a wind tunnel first...
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Old 07-23-2003, 10:06 PM
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Default Diamond Dust in air and GRRT runs great after rebuild.

hey dont some gas blowers advertise 200 mph wind?......there you go a wind tunnel
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Old 07-24-2003, 03:02 AM
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Default Diamond Dust in air and GRRT runs great after rebuild.

I exchanged a couple of emails with eagletree and it is in the plans to increase the speed limit. Don't know how much or when but they said it will be possible to mod the existing units. Will require some resistor and application changes.
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Old 07-24-2003, 03:24 AM
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Default Diamond Dust in air and GRRT runs great after rebuild.

Yes, that is the same thing they told me a few times. Saying it is one thing, doing it will require some actual action. Fortunately, the glider pilots are interested in it for the altimeter function and data logging, so I will be able to unload it easily to local fliers.
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Old 10-13-2003, 03:38 PM
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Default RE: Diamond Dust in air and GRRT runs great after rebuild.

FYI, the hi speed mod is on their site now.
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Old 10-13-2003, 04:01 PM
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Default RE: Diamond Dust in air and GRRT runs great after rebuild.

Yes, I saw that and got an Email to that effect. Unfortunately, it seems as though the error margine is greatly increased as well.
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Old 10-14-2003, 01:50 PM
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Default RE: Diamond Dust in air and GRRT runs great after rebuild.

Here's a link to a post that I made.


http://www.rcuniverse.com/forum/DDus...1199255/tm.htm
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Old 10-14-2003, 02:11 PM
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Default RE: Diamond Dust in air and GRRT runs great after rebuild.

Yes, I saw that. If the day you tried it in the car at 60 was calm, you had an 8 MPH error, which was only 13%. This is not as bad as the margin of error on the website, but it was just a -13%, if you allow for a +13% as well, now you have a 16MPH range at 60 MPH. At 150mph, this leaves a window of interpretation of 40MPH, or 130 to 170.
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Old 11-01-2003, 11:43 AM
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Default RE: Diamond Dust in air and GRRT runs great after rebuild.

Hey Flooredcobra; What type of carb ya running on that grrt and where could a guy buy one.
Thanks for any light you can shed on the subject.
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Old 11-01-2003, 03:19 PM
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Default RE: Diamond Dust in air and GRRT runs great after rebuild.

it is the .61/ .77/ Q500 R/C Carburetor for $39.95 and part number3219.

make sure you tell them that you are going to be putting it on the GRRT. They should send you a small 2 hole ring with it also and the bottom half of carb should be shaved down. The ring and 2 screws is what holds the carb on

http://morrishobbies.com/product_inf...b1e1115add9a43
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Old 11-04-2003, 12:46 PM
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Default RE: Diamond Dust in air and GRRT runs great after rebuild.

Thanks for the info. This may be the route I take if I don't go with a Webra speed 40. Still saving pennies and looking at cost vs perf. vs my pocket.
Finances can be nasty detail to consider.
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Old 11-04-2003, 07:01 PM
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Default RE: Diamond Dust in air and GRRT runs great after rebuild.

This is the set up I am using and love it. It works perfect with the dust being that is so light. The GRRT likes those small props on pipe and the DD being light has no problems yanking out of your hand at launch.

It is a pricey set up though after you get all the parts needed. It needs pipe and carb and on the other $149.95 version of GRRT it needs a small header. The FAI version the pipe just clips right on back of engine without any kind of header.

Once you get it set up right its a ball to fly. Another option would be to go with Jett. They have some powerful engines also and probably are much easier on plugs rather than the GRRT. Then again maybe not , i am not sure since i dont own a Jett.
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Old 11-05-2003, 12:14 PM
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Default RE: Diamond Dust in air and GRRT runs great after rebuild.

I have found that the OS R5 seems to do well with the GRRT. Second to that, the Durmax Gold.
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