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I have a diamond dust and a QM 40 with carburator made by jett, I would like to know if there is another prop that would fit the engine.
I Wonder if it is going to work on qm the diamond dust, what can be the diference with diamond dust with qm 40 and a qm 40 on pylon plane in terms of high speed?? if there is a pound of diference in the weight

Mike Connor

My Feedback: (5)

I sold a delta kit similar to a Dust and the Q40 engine works fine if you keep it clean enough. The QM40 plane may be faster even though it is heavier since it will likely be cleaner. The one pictured below has a QM40 Nelson engine.

Edit - As far as props, you don't have many options on a QM40 engine. Probably a 7.4 x 8 give or take a little.

daven

My Feedback: (1)

Don't be afraid to go with less pitch and let the Nelson rev. The 7.4x7.6 prop works very well, as does the 7.4x7.5.

Mike Connor

My Feedback: (5)

Thanks daven, I only know what I have read about QM40 engines. My point is don't even think about a 9" sport prop.

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Thanks Daven ¡¡¡Thanks Mike ¡¡¡too ... I really appreciatte your words.. I live in Paraguay South America and here are not use to speed yet, so there's no much information about it or a person with experience like you, so.
I'm reenforcing the total wing of dd and I'm also using fiberglass on wood and corners in order to make more durable since the engine have many rpms and power.
I'm not going to use a 9 sport prop but I think as Mike said that I can even use a low pitch in order to high revs and hace nice high speed ¡¡¡
Did you guys can tell me the speed of your qm on diamond??? is it faster than jett 60 lx on it?
Do you have some other pictures mike?

Mike Connor

My Feedback: (5)

Attached is a picture of the above plane before it was finished. This plane has flown and is fast but no official speed on it or other Dust like deltas. freakingfast, Combatpigg and chuckL on these forums have deltas with either a QM40, DF and Jett60LX engines on them. The Doppler and radar speed checks we do have put them well past 150 mph on a good run but not enough info to call one faster then the other. I suspect the cleanest airframe will be the fastest.
My site has a bunch of delta pictures for ideas. Your might check out the testimonial page also.
http://www.mikesrc.us/

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I used to have a diamond dust with jett 60lx upgrade motor, now you can see here the qm 40 on this enigne it is realley powerfull and fast almost 200 mph I thing so.
Wacht it
This is really ballistic misil

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mike I need to know how to put a counter balance spiner çç
thanks

daven

My Feedback: (1)

Here is the easiest way I have found to get the counter balanced spinner correct.

Take out the glow plug.

Turn the motor over so that it is at top dead center.

Loosen the prop nut / spinner (keeping it at TDC).

Look at the front of the motor (with the head at 12 o'clock). The thrust washer should have a notch on the outside, set the notch so that it is at 10:30 (just to the left of the head). I line the prop up with the notch, and carefully tighten everything. Make sure that nothing moved while tightening the spinner. The notch should remain at 10:30 at TDC.

After you set it a few times, you may find it easier to leave the glow plug in, and set the notch at 1:30 right as the motor bumps up on compression.

Speedy-Gonzales

My Feedback: (202)

I am the builder and flyer of the Q40 powered Screamin Demon shown in this forum and I must say it is a very rugged model when fully sheeted. I have cart wheeled it a few times on landing without a scratch. I have had some "recorded" flights showing an average of about 180 mph but nothing official to submit. After I land I notice everyone peaking out from behind benches and trees. The Nelson Q40 with the Perry/Conley #5001 Mega carb is one of the easiest running engines I have ever had. I have a .008" shim under the head with a deck height of .012" and am using the APC 7.4" dia x 8" pitch carbon prop. I'm using Powermaster 10/22 fuel. Flight times with a 5.25 ounce Tettra bubbless tank from launch to landing is about 2.5 minutes. Engine throttles like a sport engine and I set N/V so engine is turning 21,400 RPM static for launch. By the time I reach 300 feet after launch the prop is starting to bite in and the engine starts to pick up on the pipe and then all hell breaks loose!!! The throttle carb has saved my ass a few times. High rates for launch and landing and low rates only for speed flying. Model is totally erratic and unmanagable using high rate at these speeds plus you do not have time for any aerobatic manuvers. 3/16" elevon travel is PLENTY for smooth high speed flight. You will also need at least 50% expo on high rates and I have dialed down to no expo on low rates. I do not like the "mush" of expo during high speed flight. Less control surface movement on low rate with no expo but a crisp response. I must clarify one thing here....the model is not erratic....my right thumb is!!!!!

Goinstraightup

My Feedback: (26)

That's a Great Flight Report Speedy!

vicman

My Feedback: (10)

SG/Dave,
I have a question about how the engines hold up or tolerate the high speed passes. Normally we would take them up and do a split S and do the blistering dive pass. Does this tend to cause a lean out on the engine when it fully unloads? I know these engines are designed to run on the pylon course and not normally be exposed to the ballistic speed dive. If I were to set one up like this for just high speed sport/showing off will I need to worry about giving a little more turn to the rich side than I normally would?

Mike Connor

My Feedback: (5)

Where is our video?

Fxrs_tim

Vic,

Think about it this way - split S or pylon turn, both are pulling positive Gs on the airframe. You shouldn't have any issues, just set the needle so you're about 800 down from peak on the ground. Still, as w/ any Q500/Q40 motor, I would use a bubbleless tank to prevent any lean runs. The tank is cheap insurance versus a new piston/liner.

Tim

Speedy-Gonzales

My Feedback: (202)

I completely agree with the last 3 posts. I am sorry Mike for no video to date since the recordings were done by a friend with a MP3 player/recorder. I also agree with the positive G comment concerning the "split-S" which is my favorite turn-about manuver. The wide arc type turn is also impressive and the model actually seems to accelerate in the turns. I set my static RPM at about 500 RPM off peak but I am running fuel with 22% total lube and have not had a lean run yet. If you do go lean...shut it down immediately!! The bubbless tank is a must and it is also important to land "dead stick" with the throttle completely closed as to not allow any ingestion of foreign materials. I always swipe the intake venturi with a oil soaked Q-tip after each flight or turn plane upside down and flush with a burp of fuel.

Mike, You will have your video this spring. I promise!

I still have the short kit you sold me. I never started it. Eat your hearts out guys!!!!

vicman

My Feedback: (10)

The reason I asked is that on occasion I feel like my SJ.50 seems to run low on fuel in my Magnum when I go for stoopid speed pass. The best speed I had with it going by the Stalker gun was in a gentle dive instead of the split S. I have been thinking about how these passes could have an adverse effect on my better engines in the future.

I am following the 5-800 rich rule BTW

Speedy-Gonzales

My Feedback: (202)

Vicman, I am familiar with many of your forum contributions and know by reading your comments that you are a seasoned speed freak and probably have a lot more experience than I. I have seen a couple Magnums fly. Two of them shedding the wing covering on a high speed pass and that is why I feel it is imperative to have a fully sheeted wing. You can lose the covering and still have a wing to get you back to earth in one piece. They really "crack" when the covering comes off. This is the main reason I prefer the "Demon" over the DD. You will also retain a true airfoil at high speed with the sheeted wing. Many think the covering areas over an open framework will push in during speed but it will actually buldge out due to the vacuum created at the rear portion of the wing. This vacuum actually "sucks" the covering off of the wing. I have Hitec HS-225 MG servos on the elevons and am considering upgrading to JR-821 digitals but I am restricted on servo size . I have not had any problems with the 225's. I am also only using a 4.8V battery. I may just upgrade to 6.0V and see how she holds up.

freakingfast

My Feedback: (3)

I have over 250 flights with my YS 45 powered DD and over 150 flights on my DF powered DD and the covering is fine. I think you are correct, the vacuum side in a turn is under the most stress because the covering not supported, the air is trying to peel it off the structure.

With the massive power on your delta, I think you are running on borrowed time with those mini servos or you are the luckiest RC'er. Perhaps you are giving the servos the mechanical advantage at the cost of maneuverability but even that won’t last forever. When you do have problems it most likely will be a catastrophic total failure and deltas just don't fly with one control surface.
The JR-821 isn’t much of an upgrade.

You have a beautiful delta Speedy, I hate to see it die.

Mike, did you have a minimum in.oz. servo call out in your kit? If not, what do you think?

Speedy-Gonzales

My Feedback: (202)

freakingfast, I will have to agree with you on the servos and have been stewing over it since my last flight in 2008. I am going to remove the Hitec 225 MG's and see if I can get a pair of Hitec 5625 MG digitals in there. I will also be switching to a 2.4 GHz receiver. I am also considering placing the servos out in the wing laying flat instead of in the center fuselage area.[sm=thumbup.gif]

Mike, You catching all this???? [8D]

P.S. to "freakingfast"....We are all running on borrowed time!!!!!!!!

evan-RCU

The 5625s do not center well which is important at high speeds.

Mike Connor

My Feedback: (5)

I used a servo calculator and considering weight, control movement and speeds up to 180 mph, the HS-225 should be fine. They were really popular with the Q-500 guys for awhile and held up well. I run mine on 4.8V and always used nylon gears. I had JR-517 servos in my first DD with a Jett 50 for power. I had over 100 flights on it before it died and it was not a servo problem. I will not discourage better and stronger servos but do not see the need for them. Any servo can fail but the Dust and Screamin Demon do not have the weight or stiff hinge line of the whip to contend with. Speedy's flight report makes it sound like there is plenty of strength in the 225. If a more expensive servo gives you peace of mind then I say go for it.

daven

My Feedback: (1)

Vic,

IF you are using a bladder tank, and running 500+ off peak, I don't see a problem with doing split - s style high speed dives with a Nelson or Jett.

Have you run the motor I sent you?

Speedy-Gonzales

My Feedback: (202)

Mike, I am inclined to agree with you on the HS-225 MG servo integrity ! I also believe the metal gears and upgrade to 6.0V will suffice. If I lose it I can simply back off the throttle and let it float to the ground like a feather providing I have enough altitude to react in time! There is one other thing to consider. I am not hammering the sticks at 180 MPH. Even in the "split-S". My rollover on the top and downward dive is in a very large arc. No "turn and burn" type pylon manuvers.

evan-RCU: The 5625's do not center well???? That is totally new to me. I have always found the 5625's and 5645's to be crisp and stable at neutral position. Maybe you have a problem elsewhere in your flight system. I am always open to discussion and debate. Are you using 2.4 GHz or PPM/PCM decoders? That is why I am making the change to 2.4 GHz. The servo resolution is incredible with 2.4 GHz technology. There is no comparrison between the 2.4 GHz and PPM/PCM with or without digital servos. Speedy

vicman

My Feedback: (10)

[sm=red_smile.gif] Thanks

Not yet but you can tell where I'm going with my questions. The last thing in the world I want to do is accidentally smoke the engine during a "ya'll watch this" pass.[sm=stupid.gif]

daven

My Feedback: (1)

Short stroke Nelsons were pretty tough to wreck if you run them rich with a bladder.

Have at it.

Plan on 6 oz of fuel burned in about 3 minutes from the time you fire it up