SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Jul 09, 2014, 12:05 AM
Registered User
335driver's Avatar
USA, TX, Round Rock
Joined Dec 2006
440 Posts
Question
Kress Jets F-15

Question about an old Kress F-15 kit. Anyone know approx year it was released?
Building one now from an old kit a friend gave me. It will be electric powered. As it was for a .10 size IC engine and the fan unit was about 2 3/4", thought I would do a 70 mm.
Some parts were missing and the plans are very fragile but hoping for the best. Will post some pictures later. hanks for looking.
335driver is offline Find More Posts by 335driver
Reply With Quote
Sign up now
to remove ads between posts
Old Jul 09, 2014, 12:42 AM
EDF all the way!
bruff's Avatar
Gilbert, Az
Joined Jun 1999
7,939 Posts
From the early to mid 90's. I had the kit many years ago. Used an RK709 fan.. Today's 70 mm is overkill from the original power source.
Bob
bruff is offline Find More Posts by bruff
Reply With Quote
Old Jul 09, 2014, 09:08 AM
Registered User
335driver's Avatar
USA, TX, Round Rock
Joined Dec 2006
440 Posts
I guess that the date on the plans was x/x/1988 then, I wasn't sure as the print is very tiny. The plans are half/scale so only useful to see how things go together. Here are some pics as promised. I'm thinking of making it single exhaust as I don't have the parts for bifurcated tail pipe. Probably could come up with something tho'.
335driver is offline Find More Posts by 335driver
Reply With Quote
Old Jul 09, 2014, 09:51 AM
Registered User
St. Mary, Maryland, United States
Joined Dec 1996
8,303 Posts
Cool, guess the original 'battery rocket' accessories are now obsolete
Chris True is offline Find More Posts by Chris True
Reply With Quote
Old Jul 09, 2014, 10:15 AM
Registered User
Canada
Joined Nov 2000
6,956 Posts
Have your half scale fragile plan Scanned (digital file) and also turned into a Full size print at a local Reprographics shop?
Bare is offline Find More Posts by Bare
Reply With Quote
Old Jul 09, 2014, 03:50 PM
Registered User
335driver's Avatar
USA, TX, Round Rock
Joined Dec 2006
440 Posts
Bare,
I'm afraid it's too fragile to go thru a scanner. It's very brittle from being in my friend's
attic. It's hard to even unroll without ripping somewhere. But a good idea.
Chris, I didn't even know there was an original 'battery rocket' accessories.
335driver is offline Find More Posts by 335driver
Reply With Quote
Old Jul 09, 2014, 05:27 PM
Registered User
St. Mary, Maryland, United States
Joined Dec 1996
8,303 Posts
Quote:
Originally Posted by 335driver View Post
Bare,
I'm afraid it's too fragile to go thru a scanner. It's very brittle from being in my friend's
attic. It's hard to even unroll without ripping somewhere. But a good idea.
Chris, I didn't even know there was an original 'battery rocket' accessories.
Your kit is probably the original glow, in the late 90's he did a version for edf. The fan used 10 cells and if I remember right the rockets were the correct diameter for 1,000 SCR's which later became CP1,700's. "Round cells" of course. 350 watts was hot stuff. The plane of course was then a 3 pound brick

5 cells per rocket *2 rockets *1.1V per cell * 35ish amps. Fly em hot for the best performance!
Chris True is offline Find More Posts by Chris True
Last edited by Chris True; Jul 09, 2014 at 07:39 PM.
Reply With Quote
Old Jul 09, 2014, 07:10 PM
Registered User
335driver's Avatar
USA, TX, Round Rock
Joined Dec 2006
440 Posts
Chris, it is the original glow version. It's interesting the way, he had the nose pivot up to get to start the motor. Now, I need to figure where the ESC goes and the wiring etc. As my friend would say,
not a problem but a challenge .
335driver is offline Find More Posts by 335driver
Reply With Quote
Old Jul 10, 2014, 03:04 AM
Registered User
United Kingdom, England, Southampton
Joined Oct 2013
1,829 Posts
Bob Kress was chief designer of the full size F-14 so he did have a clue
Mark Powell is offline Find More Posts by Mark Powell
Reply With Quote
Old Jul 14, 2014, 02:01 PM
Registered User
335driver's Avatar
USA, TX, Round Rock
Joined Dec 2006
440 Posts
OK, question about thrust tube ? As long as the area of the outlet of the thrust tube is the same,
does it matter if it's round or elliptical? I would think it doesn't matter but thought I'd ask. The tube is parallel with the bottom of the wing, which is flat bottom, but sticks up kinda high as the fuselage slopes down. Since I'm going with a single tube, I was just wondering.
BTW, I knew Bob was chief designer of the F-14 and an early pioneer of ducted fan technology.
335driver is offline Find More Posts by 335driver
Reply With Quote
Old Jul 14, 2014, 02:06 PM
Registered User
St. Mary, Maryland, United States
Joined Dec 1996
8,303 Posts
Nope, as long as the area is the same you are good. Course it is a little hard to determine are for oddly shaped ellipses but it'll work
Chris True is offline Find More Posts by Chris True
Reply With Quote
Old Jul 14, 2014, 02:28 PM
Registered User
335driver's Avatar
USA, TX, Round Rock
Joined Dec 2006
440 Posts
Actually, I was just going to flatten the round shape a bit. I think it'll work. I'll be using an E-flite Delta V15 fan w/E-flite 3600KV motor. I think that'll be good enough.
335driver is offline Find More Posts by 335driver
Reply With Quote
Old Jul 14, 2014, 02:28 PM
Do it Right, the first time!
CoolerByTheLake's Avatar
United States, MN, Hermantown
Joined Dec 2008
5,224 Posts
Area of an Ellipse

https://www.math.hmc.edu/funfacts/ffiles/10006.3.shtml

If you didn't know already.
CoolerByTheLake is offline Find More Posts by CoolerByTheLake
Reply With Quote
Old Jul 14, 2014, 02:46 PM
Registered User
335driver's Avatar
USA, TX, Round Rock
Joined Dec 2006
440 Posts
Cooler, thanks and actually I didn't know that formula but figured a flattened circle couldn't get bigger or smaller area-wise.
335driver is offline Find More Posts by 335driver
Reply With Quote
Old Jul 16, 2014, 01:20 PM
Registered User
Ed Waldrep's Avatar
Las Vegas, NV
Joined Dec 1996
7,929 Posts
It looks from the pictures like the thrustline through the center of the exhaust tube points quite a bit upward vs the wing centerline? If so you might get quite a bit of nose up reaction when going from low throttle to full throttle. If you squish the exhaust down to an ellipse or a rectangle with circle ends (easier to calculate the area) you could get the thrustline closer to the wing incidence.
Ed Waldrep is online now Find More Posts by Ed Waldrep
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Question Kress Jets F-15 335driver Fuel Jet Talk 1 May 28, 2014 12:48 PM
Discussion my jet closet!!! F-15 106inch and F-16 100inch sherlockshah Jet Turbines 0 Jan 03, 2014 11:09 PM
Sold Fixer Specials Sport Jet 90 and Eflite Airliner TGA F-15 CRCJA Aircraft - Electric - Jets (FS/W) 1 Nov 12, 2013 03:25 PM
Sold Kress Jets RK-20 ducted fan CryHavoc Aircraft - Fuel - Jets (FS/W) 3 Sep 28, 2013 10:26 PM
Question Kress Jets F-15 ducting question stevebarrow Electric Ducted Fan Jet Talk 30 Jun 07, 2004 11:43 PM