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Jun 18, 2012, 02:31 PM
Registered User
Quote:
Originally Posted by Steve C View Post
I think twin 70's is a good idea. The T-38 fuse is wide but not tall/deep. Fitting a single 90mm fan inside will make it quite a bit bigger unless you do a hump like the Top Gun Mig 29 and F-15.

If you want really good performance from a jet, ducting is a must.
On intake it's not always needed...An intake lip on a fan scooted this 35lbs Hunter pretty good, less weight less complexity for building...

thread here - https://www.rcgroups.com/forums/show...=hunter&page=2
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Jun 18, 2012, 04:08 PM
DFC~ We Do Flyin' Right
Vapor Trails's Avatar
dang that is one great looking fan!
Latest blog entry: 68% Pitts Challenger SMASHED
Jun 18, 2012, 05:54 PM
deltas are cool
AIR SALLY's Avatar
i'll go out on a limb and say the ducts would cost @ 80.00 shipped.depends on how long they end up being . if a 70"ish size is done retracts wont cost as much either . falcon is having to pay big bucks to get HD gear for his 12 ft T-38 .all things to be concidered for marketing .
Jun 19, 2012, 06:31 AM
Hey Guys, Watch This.......
mike2663's Avatar
Before deciding on a final size for this "kit" the retracts need to be considered not only for the price but actual functioning and reliability.

Mike
Jun 19, 2012, 08:55 AM
Carbon fiber is our friend
Steve C's Avatar
Quote:
Originally Posted by erh7771 View Post
On intake it's not always needed...
You're right, it's not "needed". You will waste many watts without it though, so get out your wallet and buy bigger batteries, accept shorter flights and give up a bunch of top speed.

You have a beautiful plane, but if it were mine I'd make ducts for it and supercharge it's performance!
Jun 19, 2012, 09:46 AM
Registered User
Quote:
Originally Posted by Steve C View Post
...You have a beautiful plane, but if it were mine I'd make ducts for it and supercharge it's performance!
Not mine, wish it was....

In the video of maiden the performance was fine, don't know if hours of work and a chunk of change would increase the performance more than 10%.

There are too many 90 sized jets that are flying without intake ducting to count...Fly Fly makes a who line of jet that fly fast and efficiently without intakes...they're pretty much open bell also..

Prolly would make a good option if one would like...
Jun 19, 2012, 09:46 AM
Registered User
Quote:
Originally Posted by mike2663 View Post
Before deciding on a final size for this "kit" the retracts need to be considered not only for the price but actual functioning and reliability.

Mike
If the weight is kept around 15lbs AUW there are at least 3 options of etracts that would be fit great
Jun 19, 2012, 09:56 AM
Hey Guys, Watch This.......
mike2663's Avatar
Quote:
Originally Posted by erh7771 View Post
If the weight is kept around 15lbs AUW there are at least 3 options of etracts that would be fit great
I agree but it's seems that this is leaning toward the 144 inch version. Guess we will see soon enough which way this will go.

Mike
Jun 19, 2012, 10:28 AM
Capt. Z
falcon5's Avatar
Ed Waldrep scratch built a 90mm EDF T-38 a few years ago. He needed to over size his inlets just a little but not too much. His was 65" long
Last edited by falcon5; Jun 19, 2012 at 10:48 AM.
Jun 19, 2012, 05:27 PM
Fly more Foam
sam51401's Avatar
If Fahim does a Talon, his retracts are supplied from SpringAir. Been around for a long time and dependable. The newer choice that i went with on my A10 are the 90-120 size E-Flite retracts and i even changed the mounting around to suite the kit with out any major remanufacturing for mounting. That is another story!
Anyone have access to one of Bob's F. kits and see what size intakes he has. Im prettty sure they are a little larger than the scale of the plane and he has added the Violett 12s fan setup. Now that is an electric setup that approaches a turbine in cost$$$$$ which is the opposite way we would like to address this.
ECONOMICAL!!!!!!!!!!!!!! is the magic word of the day!
Jun 19, 2012, 05:32 PM
wannabe Jet guy
CRCJA's Avatar

Yep


I have the Bob F. T-38. Let know where you want it measured from.

Ralph

Quote:
Originally Posted by sam51401 View Post
If Fahim does a Talon, his retracts are supplied from SpringAir. Been around for a long time and dependable. The newer choice that i went with on my A10 are the 90-120 size E-Flite retracts and i even changed the mounting around to suite the kit with out any major remanufacturing for mounting. That is another story!
Anyone have access to one of Bob's F. kits and see what size intakes he has. Im prettty sure they are a little larger than the scale of the plane and he has added the Violett 12s fan setup. Now that is an electric setup that approaches a turbine in cost$$$$$ which is the opposite way we would like to address this.
ECONOMICAL!!!!!!!!!!!!!! is the magic word of the day!
Jun 19, 2012, 06:52 PM
Wowplanes.com
awrightbrother's Avatar
Quote:
Originally Posted by CRCJA View Post
I have the Bob F. T-38. Let know where you want it measured from.

Ralph
Thank you for the offer. I have highlighted the dimensions to be measured in red in the attached drawing.
Also would like to know the length & wing span of the model.
Fahim
Last edited by awrightbrother; Jun 19, 2012 at 06:57 PM.
Jun 19, 2012, 07:08 PM
Lee Liddle
Knife Liddle's Avatar
Another thing to consider is that with today's power systems, the Bob F T-38 is a good size for a 90mm to 100mm fan.
Jun 19, 2012, 07:36 PM
deltas are cool
AIR SALLY's Avatar
no offense to Ed but the nose looks short and the inlet just does'nt look right ,the line on top is too straight.so if we cheat the inlets we need to do it a little better.im sure Ed has his reasons for doing it like that .all of his scratch built planes fly very well.he has been missed around here.hope he gets back into this stuff.we need to find some gear that are'nt very tall we need a pretty thin wing to look right also.
Jun 19, 2012, 08:02 PM
Wowplanes.com
awrightbrother's Avatar
Well folks, I have looked at this every which way to Sunday.

72" does not make it in duct area and even in wing area to support the weight I estimated at about 14 lbs.

The minimum would be 108" and could be built to fly at 16 to 18 lbs. That would require 2 x 90mm with at least 8S or 10S

The more I look at this the more I am convinced that this would not be a good project to continue unless we go for at least 108". I really don't want to spend all that time and effort to design a 72 incher that would not look or fly scale.

I was just getting started on my next project when Andy's build caught my eye and I got excited and side tracked with building a 144" T38.

I think I should return to my project which is an 80" span scale Lear Jet 45XR. I will be starting a build thread for that in a few days. Here is a picture of the plane that I will be modeling.

Many thanks to all those who contributed here. I hope you will all join me at my new thread.

Fahim
Last edited by awrightbrother; Jun 19, 2012 at 08:15 PM.


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