iflyg450

The dust is one of the only deltas I have not flown. I am getting ready to start on one. I was going through my engine box and found my Super Tigre X40. It turns the APC Carbon Q40 40 props 24,000. While I have no doubt once its flying it will be pretty fast, but I am not sure what the launch will be like. Any thoughts????

evan-RCU

No problem at all. They've been flown on .25's to bigger than .60's...

iflyg450

Oh I have no doubt that it will fly just fine with the X40. My concern is the launch. The X40 turns a 7.4x7.6 to get its peak power it just doesn't give a huge amount of static thrust for launch.

combatpigg

My Feedback: (3)

I fly basically the same plane at about 4 pounds powered with a .40
IIRC the launch is at 24,000 with a 6.75 x 7 prop.
The plane needs to be let go fairly level and allowed to build up some speed before I try to input much control.
It loses about a foot or two of altitude as it moves out of my hand..so the first 2 seconds after release are the critical ones. This combo of prop and plane doesn't have any tendency to veer or roll to the left at launch..the launches are just real wimpy looking but kind of graceful... if I leave the stick alone and just let the plane climb and gain enough speed for me to start flying it.
Thrust HP calculator says that there is only 3.59 pounds of thrust at launch with my setup.

MJD

My Feedback: (1)

There are few pucker factors like the 2 seconds after launch where the model has mind of its own as the prop tries to hook up, and you have to lay off the sticks despite the temptation to start stirring. The only time I dump one of these at launch is by fiddling with the Tx. You'd think a .65 powered 32" delta would rocket out of your hand.. but at maybe 5 pounds fueled and barely over 1:1 thrust to weight static on a grossly oversquare prop (8.2 x 11), mine is a dog out of a hand launch. It gets interesting pretty quick after that though.

combatpigg

My Feedback: (3)

MJD.. the exact opposite experience is launching a 19 ounce Nelson .36 powered CL combat plane that is putting out over 8 pounds of thrust ....it's just incredible to watch and incredible to feel the pull at the control handle after your partner lets go of the model.

iflyg450

Thanks for the info. I had a feeling thats what the launch would be like. The delta I am flying now is a Picco 60 rear exhaust Laser Arrow using a hatori pipe and 11.75x8 Rev-up. While its no speed machine guessing around the 130 mark?? At launch it rips out of your hands and climbs stright up. There might be more speed in the engine but I just don't want to beat it up. The X40 sounds like it will be a good match on the dust. Its very loud having just a small open pipe off the back and no throttle. Whish there where more delta kits out there...

MJD

My Feedback: (1)

With that big prop it should pull like a mule out of the hand launch. It will cap your top speed, but I think you have a good combo there.

My little Profi .061 speedster (maybe 11-12oz AUW) - thrust to weight at launch must be about 2:1, it's like holding the leash on a hyperactive terrier. Underhand, point the nose up, gentle toss and hang on!

Some unknown guy - dum te dum dum who could that be? - needs to get his $%^# delta kits back on line.. [&o]

Speaking of noise.. yeah, the .65 Demon is on an open pipe and is freakin' loud. Glad some other poor sucker gets to hand launch it.

Planeclaims

My Feedback: (2)

Best way I learned to launch is to lightly grab leading edge of left leading edge with left hand (index finger on leading edge, like holding a frisbee), increase to 5/8 throttle (I use my chin) aim nose up 45 degrees and let go with right thumb on elevon gimbal and right wing leading edge 45 degrees low. Torque will level the aircraft as it scoots up and away. Full power is not needed and not recommended.

Steve

iflyg450

I have done that in the past, but this engine has no trottle.

MJD

My Feedback: (1)

That engine is a beaut. Always liked the looks of the X .40 and .45. I have the Bluehead X-45 FIRE pattern/sport engine, it has sat dormant since the '80's and it needs to be bolted to something.

MJD

My Feedback: (1)

Have you done this with small high pitch props?

combatpigg

My Feedback: (3)

What is your set up...?

Planeclaims

My Feedback: (2)

MJD,

I haven't tried the launching technique with small high pitch props but learned technique from those who have.....

combatpigg,

9.5 X 6 Bolly composite propeller on a TT Pro 36 with header and mousse can muffler. 6 oz fuel supply give me 8 - 10 minutes air time. Aircraft weighs less than 3 lbs.

Trying to upload a video showing the technique but have been unsuccessful thusfar.

Steve

Planeclaims

My Feedback: (2)

The video showing my launch technique is on YouTube but I cannot attach the link. If you want to view, search "diamond dust hand launch".

Steve

MJD

My Feedback: (1)

Oh yeah, I remember that video, you posted that link way back in another thread. That ought to work fine for anyone that keeps weight under reasonable control on a DD or a Demon.

[link=http://www.youtube.com/watch?v=zyVJwspCKH8]Planeclaims' hand launch technique[/link]

I was just curious how far down the path of smaller diameter/higher pitch you had gone with this technique.

I wouldn't attempt it on a modified overweight delta with a tiny prop is all.

ehelibuff

I wonder how it would be if I put my pulse jet on it? I'd have to fully sheet the wing of course.

Rudeboy

Well, you're lucky then.
6 ounces on the West 36 gives me about 2 minutes, maybe 2,5 if I fly the tank dry. But I land as soon as I hear the engine suck an air bubble, at which point there's maybe half an ounce left in the tank.

I easily go through half a gallon of fuel on a sunny afternoon with this thing.

Fanni0124

Respected Modelers! Diamond Dust electric I'm building. what electric motor
do it, what regulatory, what battery?

iron eagel

Take a look at the thread in this forum about "200mph electric delta brainstorming" as well as Screws Diamond dust threads you may get some ideas. Evanrcu has suggested a NEU that was in the 3kilowatt range that took up to a 8 cell but I can not for the life of me recall what it was. I know that your talking about a 150 -200 amp Castle Creations Ice ESC (dual heat sink) and one big battery to power it.
I would Suggest you PM Evan and ask him he could point you in the direction you want to go. You may want to look at some of the power setups used in European f3b competitions for ideas as well.
Bottom line, lots of power is needed if you want any real speed.

iron eagel

Ifly,
Did you put that x 40 on your dust yet?