Thread Tools
Oct 13, 2018, 08:34 PM
Registered User
Lynxman's Avatar
Thread OP
New Product

MIR-25 Boxfat - Large cold war inspired sports jet


I just finished this jet design. It's not a scale model, but is inspired from cold war ear jets. I call it MIR-25 Boxfat. It has 120 mm wheels for grass handling, a large wing area with a semi-symmetrical airfoil, 4į of washout and a stall fence. It is designed for 150 cm≤ FSA fans, so 145 mm fans are just right for it. It can be resized to 83,33% size if 120-130 mm fans are to be used, and smaller hardware can be used in that case. I have chosen hardare sized so that this is possible (12 reduced to 10 mm and 3 reduced to 2,5 mm for example). The intakes and exhaust are large enough for a fan like that. I'm currently printing the wing and will print the whole thing ASAP. I haven't had a chance to fly it so it's a free design for now.

Length: 2065 mm
Wingspan 1422 mm
Estimated flying weight: 8-8,5 kg
Required power: 3,8 kW
EDF size: 145 mm

The flaperons are tapered, giving increased washout effect as flaps are lowered. The elevators are all flying elevators and require high torque servos. I recommend 10 kgf+ torque rating to be safe. The rudders use 22g servos.

The landing gear uses oil shocks and hobbyking or JP retract units as described in the Thingiverse page. I have not verified the mounting hole pattern of JP units yet butthe mounts should fit according to their own dimensions. I have used 3D printed trailing link suspension with great success before in my 8 kg EL-39 so I'm not worried about their strength on this one.

The wing can be printed with one or two perimeter skin as it's very light. Each wing will weigh ~350 g with one perimeter, and probably twice that with two. The plane requires at least 300x300x320 mm print volume. If you'r printer is limited to 300x300 exactly it might need some tweaking for the slicer to figure out that it can actually print something that is fully 300 mm wide. MyJGAurora A5 has a 305x305x320 volume.

The fuselage has room for vertical battery installation and a channel for the ESC over the main air ducts, which draws air around the ESC through inlets beside the battery bay. The battery hatch (or canopy hatch) comes in two versions. Canopy03 and Canopy04 are without a canopy shape on top, so that universal lexan canopies can be mounted to the top.

I haven't designed the EDF unit for it yet. It will be a resized and refined version of the 120 mm unit I'm flying with in my EL-39. You can find my EL-39 and videos of it here:
https://cults3d.com/en/3d-model/vari...for-120-mm-edf
Last edited by Lynxman; Oct 13, 2018 at 08:55 PM.
Sign up now
to remove ads between posts
Oct 14, 2018, 01:44 AM
Registered User
japim's Avatar
One word : Awesome!!!
Three words: you are crazy

Definitely subbed.
Oct 14, 2018, 10:53 AM
Retired CAD guy
birdofplay's Avatar
errr ummm ??? Boxfat

versus Foxbat

Joke, right ? ;>}
Oct 15, 2018, 12:51 AM
Registered User
Lynxman's Avatar
Thread OP
Yes. That's called a spoonerism. It's not a scale model.
Oct 15, 2018, 07:47 AM
Retired CAD guy
birdofplay's Avatar
;>} so .... if it crashes you will end it with "rt"
Oct 16, 2018, 04:46 AM
Registered User
Lynxman's Avatar
Thread OP
If I crash then it'l be Boxfu**.

I've printed some wing pieces now, and I think the internal structure is too lightweight for this large size and one perimeters. I recommend printing the wing with two perimeters instead. It will add about 250 g to the weight over single extrusion. The fuselage should still be single extrusion.
Oct 17, 2018, 01:01 PM
Registered User
Quote:
Originally Posted by birdofplay
;>} so .... if it crashes you will end it with "rt"
Or it could be called a Second Generation Kit
Oct 17, 2018, 03:35 PM
Retired CAD guy
birdofplay's Avatar
Hey Mike, have you signed up for the late March 2019 MRRF in Goshen yet ?
Oct 18, 2018, 04:05 PM
Registered User
Quote:
Originally Posted by birdofplay
Hey Mike, have you signed up for the late March 2019 MRRF in Goshen yet ?
Havenít heard about it yet. I will look into it. It isnít that far from my place. Are you coming up?
Oct 18, 2018, 09:28 PM
Retired CAD guy
birdofplay's Avatar
I am signed up ! :>}

They sent me a notice because I was there , IN THE COLD, at the last show.
Oct 19, 2018, 04:17 AM
Registered User
Lynxman's Avatar
Thread OP
Alternative wingtips are up on Thingiverse.
Oct 19, 2018, 06:19 AM
Registered User
What an amazing design. Can't wait to see more!
Oct 19, 2018, 01:11 PM
Registered User
Quote:
Originally Posted by birdofplay
I am signed up ! :>}

They sent me a notice because I was there , IN THE COLD, at the last show.
I signed up to be there. Hopefully we can meet up. PM me near time. Donít want to hi-jack this thread. 🙂
Oct 19, 2018, 01:12 PM
Registered User
Quote:
Originally Posted by Lynxman
Alternative wingtips are up on Thingiverse.
Looking good
Oct 20, 2018, 05:19 AM
Registered User
Lynxman's Avatar
Thread OP
I've updated Fuselage01 and 02 with more internal structure, as I print themn and find things to improve, and fixed some of the nose pieces. Also refined landing gear parts. I update the files on Thingiverse when I make changes, so check the dates by the files on the files page on Thingiverse to see hat changes.

I'm almost done with the first fuselage part print. The printer started acting up after I improved cooling so the quality isn't great for most of the aprt, but it's useable wiht some post processing. The next parts wil be better. Fuselage01 printed well withone perimeter. I recommend using a smidge of Z-lift when retracting to avoid crashing with internal structure when it jogs around. 0,2 should work.


Quick Reply
Message:

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Video English Electric Lightning COLD WAR Supersonic RC Fighter Jet [UltraHD/4K] DominicM Fuel Jet Talk 0 Oct 20, 2017 11:51 AM
Discussion Cold War all over again? dll932 Life, The Universe, and Politics 7 Mar 31, 2016 08:18 PM
Discussion Videos: USN Aviation Machinists,Cold War ASW,T-Bolts, B-58s,Rommel,JG-26, PBYs & more zeno General Aviation 0 Mar 08, 2016 01:41 PM
Cool Cold War, Hot Jets.. Norman Adlam Life, The Universe, and Politics 170 Nov 16, 2013 06:27 AM
Green Air Designs New Cold War Jet Kits mjblack Electric Ducted Fan Jet Talk 9 Oct 30, 2004 04:49 AM