Dustflyer

My Feedback: (13)

Any ideas?

I have a Diamond Dust that will only hit 150 mph, and that's with a Jett FIRE 50 turning an APC 7.4 X 8.25 carbon fiber prop at 21,400 rpm. Just not enough thrust.

The airplane seemed faster when I was running a 9X10. So far the best I can do with that prop is around 16,700 peak on the ground. Haven't had a chance to get a radar reading on it yet.

If I can turn that prop at 20K I think I'll have a 170 mph airplane. The little props just won't do it even at crazy rpm.

The Jett FIRE 50 is the hottest engine of that size I know of. Is there anything else out there in the same size and weight range (12 oz without exhaust) that can turn that 9X10 faster?

rvd

Man are you ever asking for allot!!!
That's going to be hard to accomplish.. I am working on a engine right now that will turn a 10x10 17,500 but it's a 60size case.. Too much weight for a diamond dust..
I am in the same boat as you right now!! I'm looking for more horsepower but trying to keep it light.. Tough thing to do..

I designed my own racer this spring and I finally got the chance to build and fly it.. wing area is 400sq" and it weighs 3 1/2 lbs..
The airfoil shape is based on the lanier dominator but not as thick.

Words cannot explain the rush it is flying this little MONSTER!! Landings are jet like.. Totally sick..

If I stumble across something I will email you..

good luck

DMyer

My Feedback: (2)

Try a Nelson Q-500 or Q40 engine. With the right prop either should get you to about 170+ in long level runs. The Q500 should turn an APC 8.8 * 9 Pylon prop about 18,000-19,000 +. The Q40 with a APC Carbon 7.4*8.0 racing prop should get 23,000+. These RPM's are on the ground. These engines unload... a lot more... in the air. You are asking way too much of the Sport Jett. The disadvantage of using a full race engine is that you will need to land deadstick.

Flypaper 2

An appropriate ducted fan engine may do the trick also. Built for high horsepower at high rpm.

djlyon

Well if you want a physically small engine to do that, which I assume you do, try a Dooling 61

ajcoholic

My Feedback: (10)

Hmm, most guys never heard of a Dooling 61 (and if they havent, its an old ignition racing engine). Yes it was one of the best but surely wont keep up to a modern Jett or Nelson, come on now! And they are worth $650 on up to collectors anyhow.

AJC

djlyon

They also made them in glow and I agree they won't match a modern jet or nelson in the same displacement, but I do think one on 50% nitro would chase a 9/10 rev-up toward 19K and they are physically very small so they will fit where a large 40 will go.

SSAN

Dustflyer,

The reason's you're not going that fast is because your prop is WRONG. A 7.4x8.25 carbon prop was designed for Quarter Midget .40 with high timing like the Jett and Nelson Q40 turning in excess of 27,000+ rpm in the air. The F.I.R.E Jett .50 should be running with APC 8.8x9.5 to 8.8x9.75 racing prop to get the maximum efficiency. Any prop like 7.4x8.25 won't do you or the engine any good because rpm is way above it timing and power band. With your light weight DD and the props recommended, you should be able to reach 170mph with no problem at all, as long as the plane aero dynamic is clean leaving very little drag.

I assumed your Sport Jett .50 is tuned with a tuned pipe from Dub Jett himself, correct? If not, I would recommend you call Dub or send it back to him for proper tuning. And with proper tuning... a Sport Jett .50 would blow away a Quickie Nelson or Jett .40 any day. I have a few of Jett engines and including 2 BSE Quickie Jett .40 and I know it won't have the power of a Sport Jett .50 once it's properly tuned with a tuned pipe.

As for another engine that would turn a 9x10 at 20,000 rpm on the ground... the answer is, NO!!! There's no other brand that will be able to do that and you're asking too much. The best Jett, like a .60L (.60 in a .40 size case) specially tuned would probably get close, but I don't think it can. I maybe wrong, but you can call Dub and ask.

There are other variable, but that's another story...
Hope this help!

Sam

Dustflyer

My Feedback: (13)

Sam,

That's great info, thanks.

You are right, those little props just don't do the job, I proved that to myself.

Dubb was always a big fan of those props you recommend. I always thought the airplane was fastest with the sport 9X10. Sounds like I am on the right track but off a bit on prop selection. I will order those props and give it a try.

Gene

Flyboy Dave

My Feedback: (21)

A long piped Rossi .60 would probably do it,
but would be too heavy....any " 10 '' pitch
prop is hard to turn, especially wood ones.

Dave.

Dustflyer

My Feedback: (13)

Sam,

Looks like 8.75 X 9.5NN is the highest pitch racing prop they make in that size. I guess I could try a slightly cut down 9X10 sport prop.

SSAN

Gene,

Don't use that prop, 8.75x9.5NN. That prop is the older design and is not that efficient, that's why all Pylon Racer's don't use them anymore. What you need is the one recommended before, 8.8x9.5 to 9.75 pitch for the Jett .50. I have several of them and yes, they do make them and are available.

Here's a link to Darrol Cady where you can purchase that prop's... http://www.darrolcady.com/Propellers/propellers.htm
Hope this help.

Sam

Dustflyer

My Feedback: (13)

Sam,

Thanks. I've never even heard of that guy. Just goes to show you how little I know. It's kind of interesting that he lists those APC props and yet they don't even show up on APC's own prop list!

Will have to get those props and try them out.