SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Jul 02, 2007, 02:31 PM
EDF Jet Jam 2015, May 28-31st
eatond's Avatar
United States, MO, St Charles
Joined Nov 2002
1,769 Posts
Discussion
Midi F-15C with bifurcated exhaust duct and retracts

Here we go again. Based on the short lived but successful mini fan F-15 I've been working on a midi powered version with retracts. I've spent the last three weeks working on the CAD stuff. I've still got some work to do but am far enough along to post a couple of pictures showing the progress.

The specs for this bird are:
Length: 56.0 inches / 142.24 cm
Wing Span: 37.4 inches / 94.89 cm
Fan: Wemotech Midi Fan
Motor: Mega 22/30/3
ESC: Phoenix HV-85
Batteries: XPS 8S 4000
Scale: 1/13.22

My goal is to get grass field operation off my club's field where the grass is usually cut pretty short.

This is my first retract bird so if someone sees something about how I have them set up that's questionable please ask me about it.


Dan Eaton
eatond is offline Find More Posts by eatond
Last edited by eatond; Aug 12, 2009 at 01:05 PM.
Reply With Quote
Sign up now
to remove ads between posts
Old Jul 02, 2007, 06:43 PM
EDF Jet Jam 2015 , May 28-31
Kevin Cox's Avatar
St. Louis Intl, Missouri, United States
Joined Jan 1997
6,882 Posts
Looks good Dan.

I would like to mention that the support equipment for the retracts will include, nose gear servo, retract valve servo, air tank, air lines and fill valve. Small stuff, I know but it adds up fast when you consider that most require their own mounting structures. It looks like you may have a tight fit in the nose area.
Kevin Cox is offline Find More Posts by Kevin Cox
Reply With Quote
Old Jul 02, 2007, 07:28 PM
go fly! no crashes!
Synwpn's Avatar
Honolulu, HI
Joined Jun 2003
2,845 Posts
very nice Dan! signing in to watch.
Synwpn is offline Find More Posts by Synwpn
Reply With Quote
Old Jul 02, 2007, 07:40 PM
Registered User
Mr. Boogie's Avatar
Morristown, New Jersey (excl EWR), United States
Joined Oct 2003
1,110 Posts
Nice Dan,

The only comment I would add about the retracts is that you should consider mounting them so that their flanges are on the underside of the support plates. You probably know this but the CAD images shows them on top.

Boogie
Mr. Boogie is offline Find More Posts by Mr. Boogie
Reply With Quote
Old Jul 03, 2007, 10:19 PM
Hey Now
Cocoa Beach, Florida
Joined Feb 2004
2,655 Posts
On the picture showing the close up of the retracts the fan looks really short and the space between the formers looks really close together.
Can the fan really fit in there?
Scott
p.s. like mentioned before remember the air tank, air switch and it's servo along with the nose steering servo and mounting plates for all this stuff.
speleopower is offline Find More Posts by speleopower
Reply With Quote
Old Jul 05, 2007, 11:18 AM
EDF Jet Jam 2015, May 28-31st
eatond's Avatar
United States, MO, St Charles
Joined Nov 2002
1,769 Posts
Quote:
I would like to mention that the support equipment for the retracts will include, nose gear servo, retract valve servo, air tank, air lines and fill valve.
Hi Kevin,
nose gear servo - I haven't figured that one out yet.
retract valve servo - it and the retract valve will be mounted on the left side of the airframe opposite of the air tank.
air tank- the air tank is the large purple cylinder on the right side just behind the wing spar.
air lines and fill valve -I haven't figured out where I'm going to put the fill valve yet. In the cockpit would be handy but running battery leads, servo leads, and two air lines up front may get a little tricky.

Dan Eaton
eatond is offline Find More Posts by eatond
Reply With Quote
Old Jul 05, 2007, 11:21 AM
EDF Jet Jam 2015, May 28-31st
eatond's Avatar
United States, MO, St Charles
Joined Nov 2002
1,769 Posts
Quote:
The only comment I would add about the retracts is that you should consider mounting them so that their flanges are on the underside of the support plates. You probably know this but the CAD images shows them on top.
Hi Al,
nope I didn't know that but thinking about it now it makes sence. Good catch, I'll have to move those support brackets. Thanks.

Dan Eaton
eatond is offline Find More Posts by eatond
Reply With Quote
Old Jul 06, 2007, 04:55 AM
Registered User
Appie's Avatar
The Netherlands, DR, Emmen
Joined Aug 2002
1,087 Posts
Dan,

Signing on,

This looks to be a very interesting build. I'm sure you'll be able to finish it with a good result.

I did follow your previous Mini-fan F-15 build, a shame it the plane didn't live that long but it was a nice learning project for the bigger stuff.

I would be interested in building the Midi F15 also, i'll wait and see how it turns out, as said before i'm sure you'll get the job done.

Will you be selling plans for this one??


Appie
Appie is online now Find More Posts by Appie
Reply With Quote
Old Jul 06, 2007, 03:17 PM
EDF Jet Jam 2015, May 28-31st
eatond's Avatar
United States, MO, St Charles
Joined Nov 2002
1,769 Posts
Quote:
On the picture showing the close up of the retracts the fan looks really short and the space between the formers looks really close together.
Can the fan really fit in there?
Scott
Hi Scott,
yeah, that's a difficult spot. On the mini fan F-15 I was using a proven fan/motor/esc combination and since I really didn't have much choice any way I took the easy way out and just sealed it up as one big unremovable unit.
Since everything is new/unproven on this one I want to be able to get at it. On the front end of the fan I'm using the technique Ed Waldrep has suggested where you create a butt joint between the fan and a former instead of slipping the intake duct over the fan. If I can work it out on the rear end I want to make the exhaust duct section that shrinks down to the FSA after the fan a removable section so I can pull it and then pull everything else out. Still got some work to do there yet before I start cutting parts.

Dan Eaton
eatond is offline Find More Posts by eatond
Reply With Quote
Old Jul 06, 2007, 03:20 PM
EDF Jet Jam 2015, May 28-31st
eatond's Avatar
United States, MO, St Charles
Joined Nov 2002
1,769 Posts
Hi Appie,
good to hear from you. How's the F-16 holding up?

Quote:
Will you be selling plans for this one??
Probably not. I may make up a set of plans but it's a lot of work to do a good job. Not that many people building from scratch these days.

Dan Eaton
eatond is offline Find More Posts by eatond
Reply With Quote
Old Jul 09, 2007, 06:14 AM
Registered User
Appie's Avatar
The Netherlands, DR, Emmen
Joined Aug 2002
1,087 Posts
Quote:
Hi Appie,
good to hear from you. How's the F-16 holding up?
Dan,

The F-16 is still in one piece, hahaha, it's a good flier

I was changing jobs and changing houses (and did do a lot of rebuilding inside the new house) so no building & a little flying for me for the last 6 months. I'm hoping to do some building again in the coming winter. I have plans laying arround from a MIG 15, F-104 and maybe a F-15? hmm a tough choice to make...........


Appie
Appie is online now Find More Posts by Appie
Reply With Quote
Old Aug 26, 2007, 07:34 PM
Wannabe B-26 pilot!
Matt Halton's Avatar
Southwold, Suffolk, UK.
Joined Nov 2002
4,914 Posts
Wow, I didn't see this first time round Dan, but that is a beauty,you are a real dab hand with CAD.

So sorry to see you lost your CAD data on the F-105,but I strongly suggest you pick it up again, it's too sexy to be forgotten.
I feel your pain re. losing all of your HD data, I lost a 250 gig HD recently, lots of great stuff gone forever..

Keep up the good work!

Matt
Matt Halton is offline Find More Posts by Matt Halton
Reply With Quote
Old Aug 26, 2007, 08:15 PM
Suspended Account
lavochkin's Avatar
Mokena,Illinois -United States
Joined Oct 2006
5,826 Posts
Build it and offer this kit a we will come!! LOL!!!
lavochkin is offline Find More Posts by lavochkin
Reply With Quote
Old Feb 09, 2008, 05:50 PM
EDF Jet Jam 2015, May 28-31st
eatond's Avatar
United States, MO, St Charles
Joined Nov 2002
1,769 Posts
Restart

It's February and Winter is half way over. Time to get this project rolling.

I had originally intended to build my own retracts and I got a working cylinder and piston made. But it looks like I could spend the rest of the winter gettting the retracts worked out so I went ahead and bought a set of Robart 604HD retracts so I could get this show on the road.

Then I talked to Kevin Cox this morning and Kevin reminded me of a problem he had on his big F-18 using the same retracts. The nose gear on the F-18 (and F-15) retracts forward and when Kevin would try operating off of grass fields he found that a hard bump would knock the gear past the stop into an over extended position. Kevin solved the problem by replacing the retract with a different brand.

So I took apart the retract to see what the problem was. The picture shows the inards of the retract and how the stop has a rounded surface instead of flat. With a little preasure the stop deforms enough to let the pivot slide past. I was thinking about modifing the retract by milling away the rounded stop and making an insert with a flat stop. I was talking to a friend about it and he suggested adding a block to the bulkhead the retract is mounted to that will prevent the pivot block from rotating to the rear. I'll try his simple solution first and if that doesn't work I can all ways try the insert.

The other thing that's been holding me back is I just wasn't happy with the plans. In the area of the fan things were just too tight. I finally bit the bullet and enlarged the plane by 4%. That brings the wingspan up to 38.8 inches from 37.4 inches. That means I have to redraw a lot of stuff but I think it makes it a lot better plane. I'm off the week of the 19th so I'm hoping to get the changes made to the plans by then so I can start cuting parts.

Dan Eaton

104%
eatond is offline Find More Posts by eatond
Reply With Quote
Old Feb 13, 2008, 09:35 PM
EDF Jet Jam 2015, May 28-31st
eatond's Avatar
United States, MO, St Charles
Joined Nov 2002
1,769 Posts
I've been drawing away trying to get ready to start cutting next week. The picture shows the nose area with the retract in place. The purple u-shaped block under neath the retract is what I came up with to prevent the retract from over extending on a bad bump. It mounts to former 7 with a screw after the retract is installed. Since this is my first time doing retracts I have a question for you guys. What's the right sized servo to use connected to this thing? This is being built for grass field ops and it looks like the servo could take a pounding here.

Dan Eaton
eatond is offline Find More Posts by eatond
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Wattage F-86 with retracts Jorge Fernandez Electric Ducted Fan Jet Talk 12 Aug 29, 2008 07:58 PM
Build Log mini fan F-15C with bifurcated exhaust eatond Electric Ducted Fan Jet Talk 161 May 06, 2008 01:12 PM
Video HET F-15 with Electric Jet Factory retracts takeoff Ed Waldrep Electric Plane Talk 0 Apr 23, 2007 12:35 PM
Aerc F-4 with EDF 75 and retracts... Nik-rc Electric Ducted Fan Jet Talk 18 Jun 28, 2004 05:14 PM