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Jul 17, 2007, 12:25 PM
Registered User
Thread OP

Why no giant scale prop jets???

With a power to weight ratio greater than 1:1 (3D airplanes) with light gas engines and now large brushless motors, why doesn't anyone market giant scale prop jets (tractor or pusher)? I think this could easily become a whole new segment to our hobby.
Last edited by arp67; Jul 17, 2007 at 12:59 PM.
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Jul 17, 2007, 09:43 PM
Registered User
tailskid2's Avatar
Interesting concept....never thought of that!
Jul 18, 2007, 10:06 PM
Ldm's Avatar
its seems like the interest when they get larger reaches into e-flight , then , ducted , the turbine .
I agree with you but dont really know if there is a market .
Look at the ceremark line , reaching $400 for jet a retracts , larger would probably reach $600 ,
Vmar with there less then steller quality has there prop jets reaching $329 with no retracts
Jul 21, 2007, 08:45 AM
MadMonkey572's Avatar
Prop jets would be waaaaay cheaper than a turbine though... hmm... my mind is clicking
Jul 21, 2007, 09:11 AM
Intermediate Multi
Trisquire's Avatar
How about an enlargement of a '70s pattern ship with an ignition engine up front. Planes of that era looked very jet-like.

Jul 21, 2007, 07:31 PM
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I decided I will take an A-4 Skyhawk I designed & built a few years ago and put it on steroids. I still have it in my CAD program. The model is all balsa and ply construction with the engine mounted at the rear in pusher config. For the giant sport scale version, I think it would be better to mount the engine up front. My plan is to use the DA-50cc engine. The A-4 has long landing gear with the nose pitched up at a high angle when sitting on the ground, so this helps tremendously with prop clearance.....a big issues when designing a prop jet model. To get the spinner to blend better with the nose of the jet, I will probably use the A-4D model as my reference. The latter skyhawks had longer, pointer noses. I plan to use fixed landing gear on the prototype.

Jul 22, 2007, 04:21 PM

turbo prop airliners

Why not go to turbo props?
Jul 22, 2007, 08:10 PM
Registered User
Thread OP
After some additional research, I think I will switch from using the DA-50 gas engine to one of the large brushless motors now being offered from Hacker or one from Hobby Lobby. I will mount the motor at the rear of the fuse in pusher config. This will help out greatly with the scale appearance.

My goal/vision for creating giant scale prop jets is to have a model that is even larger than most of the turbine powered jets but costs significantly less and has a great power to weight ratio. I know if my giant scale A-4 Skyhawk is successful, many others will be interested in acquiring the plans and components to build their own. I want to design several other giant scale prop jets and sell the plans & components for them.

Jul 23, 2007, 03:06 PM
Intermediate Multi
Trisquire's Avatar
A nose mounted engine might provide more prop clearance during take-offs and landings. Cosmetically, I don't have a problem with a prop (or engine cylinder) on the nose.

Jul 23, 2007, 04:06 PM
Registered User
Thread OP
Tom....thank you for your input. Since I have chose to go electric with my giant scale Skyhawk, a builder could chose to mount the motor up front or at the rear.

My initial number crunching has produced the following specs for my A-4 Skyhawk project:

Motor: Hacker A60-14L brushless
Prop: 20" dia.
Fuse Length: 88"
Scale wingspan: 60"
Sport scale wingspan: 72"
Max. target weight: 18 lbs.

Jul 24, 2007, 03:20 PM
Mr. ExperiMENTAL

Good Subject!!

Hey Fellas,

I agree, I think part of the reason it has not been thought about so much is because of the lack of technology. We have more recently seen a surge in so many areas of rc. I think we are now beginning to have electric motors and equipment that are fast enough and powerful enough to do the job "well" as in efficiently. Also there are more choices than there use to be. Then again maybe no one has really done it ..has...really...done it... LOL!
I have thought about this idea myself and mainly got held up on going all out when I started thinking about the number of batteries/weight and cost of Motor and ESC that would would be imminent for such a project. I ain't I myself would not be happy with a jet that only performed like a parkflyer so to get some decent performance we would need some higher end equipment...and that means $$.

It appears that most larger models run out runners or geared inrunners and have gobs of power but only moderate speed. Not that there are not a few out their but the choices are more limited. No one has been much looking for a super fast 3D plane or a mach 1 giant warbird. I think if there was a demand the industry will begin to produce more motors specificall designed to do this job. We need a few powerful but very fast motors that run props in the 7-15 inch range with pitch speeds in excess of 100mph. Or at least that is what would catch my eye.

Now I agree it is cheaper than turbine so I think it is a route that needs exploring and a few winning combos need to come to the surface.

I am currently building a Bobcat <Modified to be "ELECTRIC">.
Link here:

It will be running an AXI 4130-20
13X5 3 blade
45amp Castle HV
9 Cell Maxxamps

Sounds like a beast, should be a hoot. Should be ready by this weekend

I used what I had as far as equipment but I think there are better combos. On the thread are a few flights of this plane on various setups.

This is great stuff to think about.

Jul 29, 2007, 07:04 PM
Simple answer

Because there isnt a market for them, nobody wants to buy them cause they cost too much and arent very good for 3D.

There are some out their though, the link geoff has posted however is just the Wren Turbo Prop engine.

The plane is a Turbo Raven and Somenzini aircraft also do a turboed bipe the Python.
Jul 29, 2007, 07:25 PM
MadMonkey572's Avatar
Originally Posted by v6focus
nobody wants to buy them cause they cost too much and arent very good for 3D.
Why would anyone want to 3D a prop jet?
Jul 29, 2007, 07:41 PM
Cause thats what the turbo raven was best at that and vertical performance.

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