Sabre XLT – A large scratch built flying wing sport jet
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Sabre XLT – Scratch built flying wing sport jet build thread
This is a step-by-step build thread for the Sabre XLT scratch built sport jet. The Sabre XLT is a large tailless flying wing. The XLT stands for “eXtra Large Turbine.” The photos below show 3D CAD models of what we are planning.
Size Matters!
Sabre Thunderbird scheme concept
If this different and unique sport jet interests you…read on.
Gary Jones
Saint George, SC
Size Matters!
Sabre Thunderbird scheme concept
If this different and unique sport jet interests you…read on.
Gary Jones
Saint George, SC
Last edited by Viper1GJ; 03-11-2015 at 05:42 PM.
#2
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First some background info.
I have been flying turbine jets for 15 years. After starting with a Kangaroo and moving to a Eurosport I wanted something different. Living in the Denver, CO area at the time I wanted something that would take off, land, and stop on a short runway when the density altitude was 8-9000’ in the summer. Most of the available sport jets and nearly all scale jets at the time could not do this.
I was initially inspired by the first Boomerang at Florida Jets in 2002.
Boomerang Florida Jets 2002
After seeing the Boomerang fly smooth and graceful aerobatics and land so slowly, I decided to design my own sport jet with a high aspect wing. I wanted it to be aerobatic, able to fly slow and land slow. In addition I did not want to pay $4k for a composite airframe. The result was the AcroJet.
AcroJet, Denver, CO 2003
The AcroJet was built around a 40% Aeroworks Giles-202 IMAC wing and tail. Construction methods were conventional IMAC style balsa, foam, and lite ply. It used a fixed gear and an external engine mounting (Kangaroo style) for reliability and low cost (no pipe). Since I knew little about aerodynamics and aircraft design I just copied what other airplanes did and used the time tested TLAR (That Looks About Right) method. The design turned out well after some adjustments. After 13 years, I still fly the AcroJet although with a bigger engine and thrust vectoring nozzle. It is my “go to jet” when everything else needs work.
For the last several years I daydreamed about building another scratch built sport jet. I like the way some of the new aerobatic sport jets fly, and land so slow, but I still do not want to pay $7K for an airframe and gear. Also most sport jet ARFs look like they came from the same cookie cutter. I still wanted something different and unique.
I have been flying turbine jets for 15 years. After starting with a Kangaroo and moving to a Eurosport I wanted something different. Living in the Denver, CO area at the time I wanted something that would take off, land, and stop on a short runway when the density altitude was 8-9000’ in the summer. Most of the available sport jets and nearly all scale jets at the time could not do this.
I was initially inspired by the first Boomerang at Florida Jets in 2002.
Boomerang Florida Jets 2002
After seeing the Boomerang fly smooth and graceful aerobatics and land so slowly, I decided to design my own sport jet with a high aspect wing. I wanted it to be aerobatic, able to fly slow and land slow. In addition I did not want to pay $4k for a composite airframe. The result was the AcroJet.
AcroJet, Denver, CO 2003
The AcroJet was built around a 40% Aeroworks Giles-202 IMAC wing and tail. Construction methods were conventional IMAC style balsa, foam, and lite ply. It used a fixed gear and an external engine mounting (Kangaroo style) for reliability and low cost (no pipe). Since I knew little about aerodynamics and aircraft design I just copied what other airplanes did and used the time tested TLAR (That Looks About Right) method. The design turned out well after some adjustments. After 13 years, I still fly the AcroJet although with a bigger engine and thrust vectoring nozzle. It is my “go to jet” when everything else needs work.
For the last several years I daydreamed about building another scratch built sport jet. I like the way some of the new aerobatic sport jets fly, and land so slow, but I still do not want to pay $7K for an airframe and gear. Also most sport jet ARFs look like they came from the same cookie cutter. I still wanted something different and unique.
#3
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Turbine flying wings are not common but I felt they could provide what I was looking for. Years ago before flying turbines, I had an interest the Bill Evans’s Simitar wings like the Desprado, and followed with interest Paul Applebaum’s success at adapting them to turbines. Also in past years I enjoyed flying Bruce Tharpe’s Delta Vortex and investigated enlarging it and converting it to turbine power. These would certainly be unique and different projects for turbine power.
High speed is not my passion, but high thrust to weight, smooth and graceful aerobatics with moderate speed, and large wheels for good performance on short grass runways was the requirement. This last requirement is a high priority with my current location in South Carolina where all the nearby runways are grass.
High speed is not my passion, but high thrust to weight, smooth and graceful aerobatics with moderate speed, and large wheels for good performance on short grass runways was the requirement. This last requirement is a high priority with my current location in South Carolina where all the nearby runways are grass.
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Enter Dagger and Lancer
In the summer of 2012 I saw a photo of Mike Oser’s Dagger. It is a tailless flying wing that was exactly what I was looking for. The Dagger photo I saw was published in APR 2012 Model Aviation magazine.
Dagger in APR 2012 Model Aviation
The Dagger design looked different, unique, and really cool to me. I immediately started daydreaming about making a larger turbine powered version. I read Mike’s description of the Dagger with great interest. He stated the Dagger wing design allowed the Dagger to fly trimmed hands off with no reflex angle on the elevons. This intrigued me so much that I made contact with Mike and began an ongoing conversation that in the last 2 ½ years resulted in our Sabre XLT design.
In the summer of 2012 I saw a photo of Mike Oser’s Dagger. It is a tailless flying wing that was exactly what I was looking for. The Dagger photo I saw was published in APR 2012 Model Aviation magazine.
Dagger in APR 2012 Model Aviation
The Dagger design looked different, unique, and really cool to me. I immediately started daydreaming about making a larger turbine powered version. I read Mike’s description of the Dagger with great interest. He stated the Dagger wing design allowed the Dagger to fly trimmed hands off with no reflex angle on the elevons. This intrigued me so much that I made contact with Mike and began an ongoing conversation that in the last 2 ½ years resulted in our Sabre XLT design.
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Mike was very helpful to me from the very beginning. I quickly discovered he had a wealth of information about aerodynamics that he applied to his design. I learned the Dagger was a prototype for Mike’s follow on design called “Lancer.” The Dagger and Lancer were no standard model airplanes. They were carefully designed and built to achieve desired results with some innovative ideas.
Mike Oser's Dagger OS 95 AX powered
Mike describes his design concept and ideas very well in his Build Log (blog) for the Lancer. This blog is on RC Groups. If you want to know what makes the Lancer a unique aircraft and see the Lancer CAD plans read Mikes blog at:
RC Groups Forums, Aircraft-Electric-Airplanes, Flying Wings, Build Log, Lancer .95 Powered Advanced Flying Wing
http://www.rcgroups.com/forums/showt...ght=Lancer+.95
As my discussions with Mike progressed and he learned what I wanted to do he suggested I wait on building my project to see how the Lancer performed. As it turned out the Lancer’s performance was a great success and Mike has even developed a new wing for it to achieve more speed. Read about it on his RCG blog.
Mike Oser's Dagger OS 95 AX powered
Mike describes his design concept and ideas very well in his Build Log (blog) for the Lancer. This blog is on RC Groups. If you want to know what makes the Lancer a unique aircraft and see the Lancer CAD plans read Mikes blog at:
RC Groups Forums, Aircraft-Electric-Airplanes, Flying Wings, Build Log, Lancer .95 Powered Advanced Flying Wing
http://www.rcgroups.com/forums/showt...ght=Lancer+.95
As my discussions with Mike progressed and he learned what I wanted to do he suggested I wait on building my project to see how the Lancer performed. As it turned out the Lancer’s performance was a great success and Mike has even developed a new wing for it to achieve more speed. Read about it on his RCG blog.
#6
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Birth of the Sabre XLT
After testing the Lancer, Mike offered to send his CAD drawings for the Lancer scaled up to what ever size I wanted. I said give me a 110” wing span. This was based on getting both wing panels cut from one 4’ x 8’ foam block with wing tips added. I took the CAD files to the copy shop and printed them out on 36” wide rolled paper. This resulted in a huge airplane! The fuse length was a little over 8’ long with huge wing panels. The root chord is about 41”, tip chord about 25”, and root airfoil is about 4” thick.
Sabre fuse concept with engine and thrust vector nozzle. Ruler is 48”
I asked Mike what are we were going to call it. He suggested he liked the names of pointy, sticking, spear stuff, so he said “how about Sabre,” I said great, lets add XLT for eXtra Large Turbine. So there is where the name Sabre XLT came from.
My construction idea was to take Mike’s enlarged Lancer plans and build the Sabre XLT with conventional IMAC style techniques using balsa, foam, and lite ply. I plan on using a Kingtech 180G tail mounted engine fitted with a thrust vector nozzle I acquired several years ago.
After testing the Lancer, Mike offered to send his CAD drawings for the Lancer scaled up to what ever size I wanted. I said give me a 110” wing span. This was based on getting both wing panels cut from one 4’ x 8’ foam block with wing tips added. I took the CAD files to the copy shop and printed them out on 36” wide rolled paper. This resulted in a huge airplane! The fuse length was a little over 8’ long with huge wing panels. The root chord is about 41”, tip chord about 25”, and root airfoil is about 4” thick.
Sabre fuse concept with engine and thrust vector nozzle. Ruler is 48”
I asked Mike what are we were going to call it. He suggested he liked the names of pointy, sticking, spear stuff, so he said “how about Sabre,” I said great, lets add XLT for eXtra Large Turbine. So there is where the name Sabre XLT came from.
My construction idea was to take Mike’s enlarged Lancer plans and build the Sabre XLT with conventional IMAC style techniques using balsa, foam, and lite ply. I plan on using a Kingtech 180G tail mounted engine fitted with a thrust vector nozzle I acquired several years ago.
#7
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I planed to convert the Lancer’s single piece wing to a two piece plug in wing tube design. Mike suggested we needed to design for 20Gs. Being the TLAR engineer that I am I decided to use two large wing tubes. These were purchased from TNT Landing Gear Products.
2” wing tubes and right main gear
I purchased some used retracts on RCU classifieds out of an FB MB 339 with large wheels and trailing link struts. I figured they would be good on grass runways.
FB MB-339 Retracts
2” wing tubes and right main gear
I purchased some used retracts on RCU classifieds out of an FB MB 339 with large wheels and trailing link struts. I figured they would be good on grass runways.
FB MB-339 Retracts
#8
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My initial fuel tank plans were two large Dubro tanks but I found a new Kevlar 180 oz rectangle tank on RCU classifieds and will use it.
With these parts on hand we had what was needed to start changing the .95 glow powered Lancer structure to nearly a double size turbine powered Sabre. Initial work started in Nov 2013. I decided to tackle the wing first.
With these parts on hand we had what was needed to start changing the .95 glow powered Lancer structure to nearly a double size turbine powered Sabre. Initial work started in Nov 2013. I decided to tackle the wing first.
#9
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With the enlarged Lancer wing prints on my table the Sabre wing design was accomplished step-by-step as construction progressed using a skill I learned over the years called “Come Along Design” or CAD. This is when you design and draw the next step as the as the project “comes along” At the present time basic wing construction is complete.
Wing structure completed so far in JAN 2015
Wing structure completed so far in JAN 2015
#10
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The fuse plans are being finalized by Mike using his skill in real CAD on a real computer. Once they are complete construction will begin. Here is a sample of where the fuse design is now.
Overall CAD model
Tail section with engine mount and vertical fin mount
The following posts and photos will detail the step-by-step progress of construction completed so far. Construction started in NOV 2013 and continues today.
I look forward to sharing our progress and learning from the RCU community.
Hope you enjoy.
Gary Jones
Overall CAD model
Tail section with engine mount and vertical fin mount
The following posts and photos will detail the step-by-step progress of construction completed so far. Construction started in NOV 2013 and continues today.
I look forward to sharing our progress and learning from the RCU community.
Hope you enjoy.
Gary Jones
#12
The AcroJet was built around a 40% Aeroworks Giles-202 IMAC wing and tail. Construction methods were conventional IMAC style balsa, foam, and lite ply. It used a fixed gear and an external engine mounting (Kangaroo style) for reliability and low cost (no pipe). Since I knew little about aerodynamics and aircraft design I just copied what other airplanes did and used the time tested TLAR (That Looks About Right) method. The design turned out well after some adjustments. After 13 years, I still fly the AcroJet although with a bigger engine and thrust vectoring nozzle. It is my “go to jet” when everything else needs work.
#14
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Sabre XLT planning and design.
Here are the CAD drawings for Mike Oser's .95 powered Lancer.
Asked Mike to send me these drawings scaled up to a 110" wing span. Here is what I got.
[ATTACH]2064276[/IMG]
From this I developed a concept drawing for the Sabre turbine
My initial concept was for lite ply fuse sides and balsa covered foam top hatches. Servo operated clamshell speed brakes under the rudder.
The wings were conventional balsa covered foam cores. Materials were ordered and wing construction began first.
Here are the CAD drawings for Mike Oser's .95 powered Lancer.
Asked Mike to send me these drawings scaled up to a 110" wing span. Here is what I got.
[ATTACH]2064276[/IMG]
From this I developed a concept drawing for the Sabre turbine
My initial concept was for lite ply fuse sides and balsa covered foam top hatches. Servo operated clamshell speed brakes under the rudder.
The wings were conventional balsa covered foam cores. Materials were ordered and wing construction began first.
#15
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Sabre XLT wing planning and design.
NOV 2013
Wing sheeting layout planned, first materials arrive, and wing tubes and main gear planned. All this information is uploaded into the TLAR computer and the CAD (Come Along Design) tools are used to finalize the final drawing.
NOV 2013
Wing sheeting layout planned, first materials arrive, and wing tubes and main gear planned. All this information is uploaded into the TLAR computer and the CAD (Come Along Design) tools are used to finalize the final drawing.
Last edited by Viper1GJ; 01-16-2015 at 06:09 PM.
#16
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Sabre XLT- block cutting and squaring wing core blanks
DEC 2013
4'x8'x5" foam slab purchased from bulk foam supplier near Charleston, SC.
Old variable transformer dragged out of long term storage and tested. One of two new cutting bows built.
Foam cutting squares are aluminum framing squares with aluminum U channel epoxied to short side and extending below base. Base is two layers of heavy MDF for weight.
60" bow used for long cuts initial cuts.
Middle cut set up
Foam slab cut in half
Block ends squared up
Wing shape layout
DEC 2013
4'x8'x5" foam slab purchased from bulk foam supplier near Charleston, SC.
Old variable transformer dragged out of long term storage and tested. One of two new cutting bows built.
Foam cutting squares are aluminum framing squares with aluminum U channel epoxied to short side and extending below base. Base is two layers of heavy MDF for weight.
60" bow used for long cuts initial cuts.
Middle cut set up
Foam slab cut in half
Block ends squared up
Wing shape layout
Last edited by Viper1GJ; 01-16-2015 at 04:56 PM.
#17
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Sabre XLT- block cutting and squaring wing core blanks
DEC 2013
Wing core blanks cut out. Work tables are 8" long.
I discovered the top and bottom of my foam billet was not flat so guides were made to square the top and bottom flat sides.
DEC 2013
Wing core blanks cut out. Work tables are 8" long.
I discovered the top and bottom of my foam billet was not flat so guides were made to square the top and bottom flat sides.
Last edited by Viper1GJ; 01-16-2015 at 05:07 PM.
#18
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Sabre XLT wing half ribs
DEC 2013
Using more CAD (Come Along Design) and TLAR the wing half ribs are planned and laid out on the foam.
Slot cutting templates are cut from 1/4" luan plywood.
Slot templates are fastened to the foam with dry wall screws.
Templates ready for first cut.
A new deep throat foam cutting bow made for slot cuts.
Slots are cut one by one
Slot testing with 1/8" ply circle
DEC 2013
Using more CAD (Come Along Design) and TLAR the wing half ribs are planned and laid out on the foam.
Slot cutting templates are cut from 1/4" luan plywood.
Slot templates are fastened to the foam with dry wall screws.
Templates ready for first cut.
A new deep throat foam cutting bow made for slot cuts.
Slots are cut one by one
Slot testing with 1/8" ply circle
#19
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Sabre XLT wing half ribs
DEC 2013
More slots cut
Deep throat bow
All three slots cut on left panel
All slots pass the TLAR test!
1/8" plywood half ribs cut
JAN 2014
1/8" plywood ripped on table saw
Test fit into slots and each length marked
Cross cuts on mitre saw
Rib blanks in slots
DEC 2013
More slots cut
Deep throat bow
All three slots cut on left panel
All slots pass the TLAR test!
1/8" plywood half ribs cut
JAN 2014
1/8" plywood ripped on table saw
Test fit into slots and each length marked
Cross cuts on mitre saw
Rib blanks in slots
#20
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Sabre XLT wing half ribs
JAN 2014
Ribs stacked and secured with servo screws, marked and drilled for 2" wing tubes
Rib stack after drilling
Ribs laid out for a TLAR look see.
JAN 2014
Ribs stacked and secured with servo screws, marked and drilled for 2" wing tubes
Rib stack after drilling
Ribs laid out for a TLAR look see.
#21
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Sabre XLT cutting wing tube holes
JAN 2014
More designing as the project comes along or Come Along Design (CAD) for the wing tube holes. This CAD is used when you don't know what to do next till you see and touch the part and then figure it out.
Plywood templates for making access holes to cut the wing tube holes are attached to top and bottom of foam blanks.
Access hole templates installed for cutting.
Access hole plug being removed
Wing tube cutting access holes cut
Ribs used as cutting template for wing tube holes. Small slots cut at top of each rib hole to allow hot wire inside the wing tube hole
1st rib fastened to wing root as a template with tape. 3rd rib in its slot.
Hot wire inserted through slots in top of plywood rib templates and moved around wing tube hole. Sock weights help keep foam from moving. Tube core removed for test fit.
JAN 2014
More designing as the project comes along or Come Along Design (CAD) for the wing tube holes. This CAD is used when you don't know what to do next till you see and touch the part and then figure it out.
Plywood templates for making access holes to cut the wing tube holes are attached to top and bottom of foam blanks.
Access hole templates installed for cutting.
Access hole plug being removed
Wing tube cutting access holes cut
Ribs used as cutting template for wing tube holes. Small slots cut at top of each rib hole to allow hot wire inside the wing tube hole
1st rib fastened to wing root as a template with tape. 3rd rib in its slot.
Hot wire inserted through slots in top of plywood rib templates and moved around wing tube hole. Sock weights help keep foam from moving. Tube core removed for test fit.
#22
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Sabre XLT cutting wing tube holes
JAN 2014
Slot in top of rib template for inserting hot cutting wire
Wing tube sleeve test fit
Both tubes inserted and fit ok
End of wing tubes supported by 1/8" plywood half rib
Both tube holes good to go
Wing panels are joined together for that TLAR quality control check.
They are big…really big.
Stood the wing cores up against the shop garage door for a size look. This was my first real clue of how really big this thing will be. The root chord is about 41”, tip chord about 25”, and root airfoil is about 4” thick.
It is really big!
Next phase is airfoil templates. Stay tuned.
JAN 2014
Slot in top of rib template for inserting hot cutting wire
Wing tube sleeve test fit
Both tubes inserted and fit ok
End of wing tubes supported by 1/8" plywood half rib
Both tube holes good to go
Wing panels are joined together for that TLAR quality control check.
They are big…really big.
Stood the wing cores up against the shop garage door for a size look. This was my first real clue of how really big this thing will be. The root chord is about 41”, tip chord about 25”, and root airfoil is about 4” thick.
It is really big!
Next phase is airfoil templates. Stay tuned.
Last edited by Viper1GJ; 01-16-2015 at 07:01 PM.
#23
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Join Date: Jun 2002
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This is awesome. I have always wondered how to do these things you are doing, and you have showed me how simple it can be with the correct equipment and knowledge. I am looking forward to following your progress. Great instruction and photos.
Jay
Jay
#24
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Thanks Jay.
Its been fun but slow due to my work schedule and some deaths in the family last year. However, I am now retired and hope to make steady progress this year. Some of this is my first time at it also. Like I said above, there was no real drawn out design for the wings except for Mike Oser's airfoils and plan form. I sort of created the enlarged Sabre wing from his drawings and then made up the structure as it came along. Such are my CAD (Come Along Design) jokes above.
The airfoil templates are next.
Gary
Its been fun but slow due to my work schedule and some deaths in the family last year. However, I am now retired and hope to make steady progress this year. Some of this is my first time at it also. Like I said above, there was no real drawn out design for the wings except for Mike Oser's airfoils and plan form. I sort of created the enlarged Sabre wing from his drawings and then made up the structure as it came along. Such are my CAD (Come Along Design) jokes above.
The airfoil templates are next.
Gary
#25
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Sabre XLT Airfoil Templates
JAN 2014
If you read Mike Oser's Lancer blog referenced above you will know that the specially designed airfoils are a major part of the Lancer's performance. I tried to follow exactly the airfoil contours when building the Sabre wings.
Mike provided full size CAD drawings printable on 8.5 x 11" tiled paper.
Tiled airfoil patterns cut and taped together, then cut to rough shape, and sprayed with removable spray mount adhesive
Patterns laminated to 1/4" birch plywood blanks
Patterns cut out on band saw
Templates sanded smooth with sanding bar
Hot wire run off guides installed into the leading and trailing edges of the templates.
1/16" holes were drilled into trailing edge and into top and bottom of leading edges, parallel to the center line of the templates.
Then pieces of 1/16" music wire are inserted and thin CA glued into the holes leaving about 2-3" sticking out.
JAN 2014
If you read Mike Oser's Lancer blog referenced above you will know that the specially designed airfoils are a major part of the Lancer's performance. I tried to follow exactly the airfoil contours when building the Sabre wings.
Mike provided full size CAD drawings printable on 8.5 x 11" tiled paper.
Tiled airfoil patterns cut and taped together, then cut to rough shape, and sprayed with removable spray mount adhesive
Patterns laminated to 1/4" birch plywood blanks
Patterns cut out on band saw
Templates sanded smooth with sanding bar
Hot wire run off guides installed into the leading and trailing edges of the templates.
1/16" holes were drilled into trailing edge and into top and bottom of leading edges, parallel to the center line of the templates.
Then pieces of 1/16" music wire are inserted and thin CA glued into the holes leaving about 2-3" sticking out.
Last edited by Viper1GJ; 01-17-2015 at 12:43 PM.