Tomcat_104

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I'd like to know are there any Aerospace Engineers out there? I'm looking for an alternate propulsion system for a F-14 jet.

My son is a MAE who just graduated with a BS and is studying for his Masters but has no experience to offer me. I can use a little help here.

David

I just re-read my post and it appears I forgot to mention EDF as my main thought. choose from.
I've all but rued out turbines because of the costs and I'm worried about EDF's and their potential lack of power.
My Tomcat has a projected weight of 28 pounds and I just want to know how much power I really need and what power sources are available for me to

da Rock

I think you'll have a better chance getting help from the engine forums or the electric forums. Power systems fly planes but really aren't as 'aerodynamic' as they are power systems.

Also, your requirements are pushing the envelope beyond what most average modelers have readily available in today's market. I'm guessing there aren't a lot of applications that use edfs/motors the size you're going to need.

BMatthews

That 28lb figure suggests that it's the really big design that I've seen. The one with the roughly 8 foot span and 12 foot length?

If I'm right I believe that it came out at the dawn of the model jet turbine age and in the dusk of the ducted fan options. As such a pair of the old engine powered ducted fan units powered by suitable electric motors might fly it. THe trick will be to find motors that replicate the power and RPM of the typical Rossi .90DF engines and similar that were used on such fan units. As I recall at full revs and sucking back gobs of higher nitro glow fuel those engines were putting out something like 6HP. Now we have electric motors that are used on the big aerobatic pattern models but I don't think they are out there at the sort of Kv values that you'd want for an EDF conversion of this sort. Basically they are set up for turning props at moderate RPM instead of fans at up around 18,000 RPM. So you may need to look at rewinding the armatures to alter the Kv values.

Battery packs will cost a lot as well. You're looking at rather brick like stacks of series and parallel similar to those used in those same big aerobatic models. Expect to pay up around $300 for a suitable pack. Then you need a snazzy big buck charger to pump them up. And they aren't light either.

All in all by all means to the research in these directions. But don't be surprised if you find that it's simply not practical to use electric power. Or that if there are suitable motors that could be used in the glow powered fan unit conversions that the final bill is up there pretty close to the same as buying a pair of turbines.

wellss

youtube is your friend

http://www.youtube.com/watch?v=2-thF4saoK8

Art ARRO

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The youtube video depicts Bob Fiorenzie flying his Yellow Aircraft F-14 Tomcat powered by twin BVMEVF fan units. I understand that this model was originally fitted with twin JMPDynamax fan units with OS 91-VRDF glow engines and converted to EDF. The F-14 is no longer kitted by Yellow Aircraft although there are several kits in various stages of construction/repair. I believe the scale is 1/9th for the Yellow offering. You can probably google "Bob Fiorenzie" for further info along with bvmjets.com for the EVF fan units. A 1/7th scale F-14 ARF is sold by Fly Eagle Jets but there is a huge thread of the inflight structural failure of this model on the RCJets Forum.

Art ARRO

Johng

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I'm here as an aerospace engineer with a lot of various experience inthe field. I can tell you just about none of that bears on fan/motor selection as much as familiarity and experience with the products that are out there. I would go to the EDF forum on RCG and start a discussion about what would work for your airframe.

FWIW, Fiorenze flew the Tomcat at our Giant Fly in Febuary and it absolutely honks.