800mm Swappable Warbirds (that actually fly)

by ultramicrobe | April 6, 2014 | (38) Posted in Projects


800mm swappable warbirds - these ones actually fly. 

Like many other urban RC fliers, I have an interest in smaller planes. Having something small enough to toss in the car and fly in a small park where you can keep the space contained is very appealing. However, I suspect my experience with small foam planes is also shared with many others - they tend to suck. 

I have been thinking of tackling this problem for some time, and was inspired once again by FliteTest, but this time in an unusual way. Recently they reviewed three HiTec “Weekender” warbirds, which are 800mm foamies. The FliteTest guys were struggling to say something nice about the way they flew (the consensus was they shared similar bad habits with actual WWII fighters were). More recently they also introduced their giant 200% series, which is fun, but lets face it - that is a building challenge but it’s not surprising they fly. 

I think there is an idea that this is an unsolvable aerodynamics problem, but my totally uneducated guess has been that this is a weight:power ratio problem. Most small commercial foamies get around this through speed - they fly fast, or very fast, and if they don’t they fall out of the sky. Obviously this is not relaxing, small mistakes tend to lead to bad things happening, and it kind of eliminates the one advantage since you still need a big space to fly them safely. I have made several planes that flew way better than their commercial counterparts, I assume because they are so much lighter, so I thought I would give 800mm fighter planes a try. The results were portable planes with flight characteristics WAY past my wildest hopes. 

 I have previously posted designed of two fighters in the 1000mm-11000mm range that flew really well, much like their commercial counterparts, the Messerschmitt Bf109e (http://www.flitetest.com/articles/foamboard-messerschmitt-bf109-based-on-ft-spitfire), and the Mustang P51D (http://www.flitetest.com/articles/swappable-p51d-mustang-based-on-ft-spitfire). So I decided to make one of each with 800mm wingspans, to make 800 size powerpods, and try out some different motor/prop/battery combinations to see what happens. I basically used the exact same plans as I have posted, with modifications to account for the thickness of foam sheets (which does not reduce with scale) and to take off some weight and make the design simpler (less cutting). Below I describe the process quickly, and concentrate on how they fly. 

Here are some pictures of the real things - a P51D and a desert model Bf109. I recently was fortunate to spend an afternoon at the RAF museum in London where these are (Colindale: http://www.rafmuseum.org.uk). It is excellent, and has an amazing collection of very rare planes, as well as lots of information. Comparable to the Smithsonian Udvar-Hazy Centre. I have updated all my old posts to include pictures of the actual planes and hope to keep doing this in future posts. 


Here is a movie focusing on flight characteristics - launches, slow low passes, gliding, aerobatics, landing. It includes some on-board footage of aerobatics, and you will see my favorite thing is the vertical climb while spinning. 


Here is another one by my flying friend Ed that has some nice comparisons with the full size planes. This focuses almost entirely on the Mustang, and at the end has some nice clips where you can hear how the full size mustang screams when it dives - a nice and un-planned feature of the air scoop I think. 


Reduce - Reuse - Recycle

Another impetus for this was to use up the huge pile of leftover foam sheets I was generating. So these planes were made 100% from leftover pieces. In fact, the wings and fuselage can be cut out of the leftovers from wings and fuselage of their big brothers - the little pieces were all cut from scraps. No full foamboard sheets were harmed in the making of these planes. 

Re-using excess foam sheets - this Mustang wing is cut from the leftover from a Stuka wing


Step 1 - modifying the plans

To make the plans, I simply took the existing Messerschmitt and Mustang plans, and reduced them to 80% size. When you do this a small number of changes have to be made to account for the fact that the thickness of the foam remains the same, 4mm. This mostly affected the corners of the fuselage and powerpod, the holes for the wing, and the way the tail attached, so I made these changes to the plans, and re-posted them below.

I also made another change for simplicity - I removed all “tabs” in the design except in the tail (so no more tabs in the spar, fuselage, formers, or mustang scoop). This made the cutting way easier and did not seem to affect the strength. I also simplified the spar, and added a wing servo cut-out since the thickness of the wing now no longer allows the servo to be completely inside - it now nicely sits flush with the bottom surface.  

Step 2 - cut out all the pieces

This, as I noted above, is a good time to use up those weird-shaped pieces of foam you have left over from other planes. I managed to use up most of mine and used no fresh sheets at all. Hinges are exactly the same. 


Step 3 - assemble the planes as described for full sized versions

This is the same as the full sized planes the following exceptions:

1. Wing Spar. the wing spar is a simple 8mm piece of foam folded back on itself, with no tabs or angles. I found it was stiffer when the two layers are sideways rather than upright (so the size you cut almost does not matter since the spar is 2X the foam thickness).

2. Wing Assembly. When the wing halves are complete, you will note the spar sticks out a lot and lacks the dihedral angle. Simply trim it to stick out about 10-20mm, then trim the bottom a bit to make some angle - you don’t have to be exact, the wing is going to be very strong. then fit the wings together so one spar is forward of the other and the leading and trailing edges match up - usually one spar is a little forward of the other anyway, and if not just force them - it won’t matter (you could probably cut them right off). When you glue the wings together, use piece of foam cut to 80mm in height to prop up the one wing to give the correct dihedral.


3. Paper upper decks. I found the tape was not holding the paper down well, so I glued it. This is likely a good idea in general. I used a piece of excess foam to press it down while it set to keep a nice flat joint (see below).

Gluing the read Mustang deck

Basic form of the Messerschmitt done

Basic form of the Mustang

Step 4. The 800-powerpod. This has proved useful when one motor failed or broke, so I am glad I kept the swappable mode. The powerpod is the same but scaled down, shorter and simpler (no tabs). I tested several motor/prop combinations and will outline that further below. With the motor I chose it is REALLY important to give it the right thrust angle (down and to the right). I used an X- configuration on the mount, with two nylon washers on the upper left bolt and one on each of the upper right and lower left. I also strongly recommend bolts and lock nuts on the top two mount holes because it’s easy to pop the motor off on a bad landing. For the bottom two I use screws since they end up over the foam and not the inside cavity of the pod. 

Fitting the powerpod into place - the space between the pod and wing is EXACTLY enough for an OrangeRX reciever. I jam it in there for extra support for the powerpod. 

Step 5. Painting. I skipped any fancy taping to keep the weight down, and because it is a lot of work, though in retrospect weight likely would not matter. Painting is important though, to give you good perspective when flying. I went for contrasting colours. The Messerschmitt is painted like the desert ones were, and this works great. The blue bottom and sand top stand out  really well, and the top is light enough that you get good definition in the air. You can follow the plane even from quite a distance. The Mustang was painted silver with red wingtip and nose tape and also stands out well. Decals on the Messerschmitt were just printed on paper and glued on before the last varnish step. 

The order of events to get a good solid finish that is sufficiently water-resistant (even for Vancouver) is:


  1. Oil based varnish (I use standard Minwax polyurithane like I use on wood)
  2. Water based acrylic paint (I use cheap craft paint, available in small bottles for $2 at Michaels craft store). I have a compressor, so I got an inexpensive spray gun (not an air brush, but a “touch-up” gun for automotive work - you can cover a plane in about 30 seconds) and do a few light coats (2 or 3 depending on the colour) 
  3. Water based varnish (I use Minwax Polycryl, which I just had around)

Right after paining (always spray outside of course)


Step 6. Canopy. Making a clear plastic canopy actually really makes a big difference in how the plane looks, so I recommend doing this rather than the common alternatives like black paper. 

The Messerschmitt canopy is the same as the larger one, scaled down. It is included in the plans. Cut and fold, then use clear packing tape pieces to tape the joints into 3D shape. Glue the whole thing into place on the fuselage, then use clear packing tape to further secure it. The frame parts are black tape.  

Messerschmitt canopy ready to glue into place

The Mustang front screen is also included, but the bubble is not because it is a 3D piece of plastic. Easy though. It is taken from the shoulder of a standard 2L plastic pop bottle. Simple cut out a piece that looks like the one below, so the large arc is 110mm (i.e. the length bent up you can see below) and the length is about 90mm (i.e. the forward-aft distance of the bubble canopy). Bend it slightly so there is about 5mm overlapping with the fuselage, then mark the outline of the canopy against the fuselage with a marker. Glue it into place (put the glue on the fuse, not the canopy because the clear plastic warps when the glue is too hot), then also tape it into place with clear packing tape. Fold the front screen and tape it together with clear packing tape, then use the same to attach it to the front of the bubble canopy and glue down the front. Tape it down too. Then add the frame parts cut from grey duct tape. 

Gluing bubble canopy into place first, then add front windscreen

Canopy joints are tapped with clear tape first, and then glued and taped into place on the plane. This is the Mustang front windscreen.


I tried three different motors and three props. I used a 25amp ECS all around and this seems to work fine. 


First up was a HexTronic 24g 1500kv (http://www.hobbyking.com/hobbyking/store/__4859__hexTronik_24gram_Brushless_Outrunner_1500kv.html?strSearch=1500kv). I burned this out after 1 battery (and learned the Messerschmitt is a great glider). 

Second up I tired the Turnigy Aerodrive SK3 2826 series. These are good sized motors but lighter than some of the equivalent powered outrunners. These functioned very well, and I used two different ones. The 1130kv (http://www.hobbyking.com/hobbyking/store/__18152__Turnigy_Aerodrive_SK3_2826_1130kv_Brushless_Outrunner_Motor.html). motor worked adequately for sedate flying, but lacked much punch. This is the motor that is usually on the Mustang, and probably accounts for why most of the footage in the movie is from the Messerschmitt. 

The Motor I ultimately recommend is the Aerodrive SK3 2826 1240kv (http://www.hobbyking.com/hobbyking/store/__18115__Turnigy_Aerodrive_SK3_2826_1240kv_Brushless_Outrunner_Motor.html). This motor performed very well with a number of props (see below), and I recommend it or something like it. 



9X4.5SF - This is a floppy SF prop, and worked adequately well, but led to a lot of vibration, so it was noisy and a bit sloppy. 

8X4 APC - this worked ok for sedate flying. 

9X6 APC - I thought this was going to be overkill, but it worked VERY well when used with the third motor. Makes for a nice quite flight, with huge amounts of power. Can go fast if you want, but also makes for nice slow flights too. 



This is a 3S system, but to keep the weight down I used 1300mAh batteries. These are fine and give 10-12 minute flight times (with the crazy vertical spins featured in the movie you get around 10 minutes, but I have never actually killed the battery). I also used a 1500mAh and it worked about the same with expected longer flight times. 

A nice tip is to put an elastic on the skewer to hold to in place, and at the same time you can use it to hold the battery in place.  



The whole point of this is to make an 800mm plane with excellent flight characteristics, so lets break this down. 

C of G. The Centre of Gravity should be right under the wing spar. This works well with the battery (1300 or 1500mAh) placed about even with the firewall, so nothing unusual. I put Mobius and HobbyKing Wing Cams on periodically and they were fine. I made the Messerchmitt tail heavy with the heavier HK camera once and it flew about as badly as you would expect (the vide of flying with Eagles is like this), but gave no real problems except landing was very poor. The Mustang seemed more sensitive, but this was maybe because it had the smaller motor. 

Take off. Easy hand launch at 50% throttle and a gentle throw at 45 degrees. I discus throw from the wing, but underhand also works. I tried a vertical take off from stationary and it worked too, but I don’t know why you would bother. My planes needed a little trim because I make the tail really badly crooked. 

Calm flights. These planes are easy to fly at low speeds or scale speeds. They are typical bank-yank controls, and I mixed a little rudder in with the ailerons to smooth it out even more. They do nice wide banking turns, or can come around very tight in a small area. If you dial down the ailerons a bit (say 80%) then you have power to climb out of any trouble without loosing it. They look nice on low passes.

Aerobatic flights. I was shocked at how nimble these planes were. They have great roll rates and very scale loops. Rolls are very nice, without a huge loss of altitude (just a little pulse of down in the middle is all you need). With the power of the 9X6 and a decent motor one of the funnest things i found to do was high speed vertical spins! Check out the movie. They just love doing this and climb out of the spin nicely. Pull out of dives well and do a nice job with snap rolls, hammerheads, and other basic moves I can do. I have not tried actual 3D stuff, but that is not the point.  

Gliding. This is an acid test for a small plane. Kill the throttle and what happens? The answer is, nothing much happens. Check out the movie for a couple of glides. It is smooth and steady - no inclination to stall or tip stall from the Messerschmitt in particular (did not test the Mustang so much). You can glide the Messerschmitt across a soccer pitch without much altitude or effort, and when you hit the throttle it recovers from the glide very nicely and jumps right back to normal flight. 

Wind. Another acid test for small planes. Often the wind bashes them around like crazy and tips catch the wind badly on turns. These planes maidened on a windy day as it turned out, and they flew fine. They bump around as you expect, but importantly they stay level and self correct very well. They have flown in very windy conditions, including regular gusts of around 15k or more and it was nothing that the power could not compensate for. 

Landing. Kill the throttle and glide, since with the 9” prop you get a lot of leverage against the firewall if you hit it spinning. give it a little flair right as it hits the ground, and you are good (see the movie). 


There are examples of most of these things in the video linked above, so if you are interested have a look. Its short and I tried to make it amusing. in summary, I have flown a lot of 800mm or so planes because I want one badly, but they are all pretty crap. I built these plans hoping that they would be tolerable at best. So I have been very very pleased. In fact, these are my goto planes now for any reason. They fly better then the full size ones, so why not? 



Below are plans for the 800 series Mustang and Messerschmitt. The wing and the fuselage are shared (the front of the Mustang fuselage is actually slightly different, but it's trivial so I did not bother with two different plans. If you want just freehand the difference). 


Powerpod for 800mm series


Messerschmitt Wing & V Stab  (also Mustang Wing)

Messerschmitt Fuselage & H Stab  (also Mustang Fuse)

Messerschmitt Formers

Messerschmitt Decks


Mustang Tail & Formers

Mustang Scoop & Canopy

Mustang Decks


For full build instructions, please see the original posts (and also linked below)

Mustang Build Instructions:


Messerschmitt Build Instructions:





Foam Addict on April 8, 2014
Great article, nice...nice... Oh who am I kidding, ME-262!!! When might the plans for that beauty be coming out?

JK, excellent content as usual. I might put one of these together for college!
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Balu on April 8, 2014
Wow. That's great. FT should make an episode for these.
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PeterGregory on July 13, 2014
I agree with Balu - the FT guys had mentioned they were going to do more warbirds, and on a recent podcast said they got busy in the summer and got away from it. A caller on the podcast asked for other than allied planes to round out the field. Ultramicrobe, I think you have the solution they should use. I've heard from Flynn that these fly really great and have put them on the list for my builds.
Great job on breakthroughs in 800mm flyable swappables, and your finishing is even great - nice artistic touches. Thanks for sharing with the world and me.
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ultramicrobe on July 18, 2014
Thanks for the nice comments. I agree, it would be good to have more variety. I wonder sometimes if enemy planes are just not as popular, but I mostly just build ones I think are interesting. I also posted plans for the larger bf109, and also the Stuka is a surprisingly good flier that I would suggest for slightly harder build (but it drops bombs, so that's gotta be worth something).
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Flying Penguin RC on April 8, 2014
Nice work. They look like they fly great. What's the big white one in the back of the car?
behind the painted planes.
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ultramicrobe on April 8, 2014
I see my secret project is out of the bag! ha ha. I am making a ME262 with swappable EDF power pods. I test flew the air frame the same day I maidened the complete 800s, so it was in the car too. Unfortunately one of my EDF units had a dud motor, so I am waiting for a replacement to see if they are going to be powerful enough. So the airframe test used the power pods from my Mitchell bomber (it flew just fine by the way, and looked pretty cool in the air). I will post it all in good time, and plan to make an adaptor to install standard prop-powerpods for the EDF-adverse.

But seriously, this 800 Messerschmitt flies way better - its my #1 right now.
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andre on April 8, 2014
Great stuff.

Right now the only plane in the hanger that will fit in my small coupe is the FT-Racer.
All the other birds have a wing span that just wont work. Fine in the daily driver...

And while I love the racer it is a touch big so a smaller bird would be perfect.

That said I have the BB training project to get under way first ;) So many ideas so little time :)
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andre on April 8, 2014
BTW I've been using TGY Slow Fly 9x6 props. Takes a lot of glue to get the hub to balance but other wise they are really nice.
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andre on April 8, 2014
And 3rd comment. Ditto on the foam. I hold onto most of my scraps until the pile is overwhelming.
My son has been using bits to make his own gliders to experiment with as well.
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andre on April 8, 2014
BTW do you find air brushing makes the paper feel more brittle?
I've not seen anything to make me feel it is lessening the strengthen but it feels brittle compared to the stock white?

I've taken to simply adding accent colours and leaving the base of the plane white.
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nerdnic on April 8, 2014
I have the same issue and also looking for a solution.
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ultramicrobe on April 8, 2014
I never spray before varnishing (because I only use water based paint), but the varnish gives that hard shell feel. But I believe it makes them stronger. Here, waterproof is essential so I would do it anyway, but I think varnishing is the single best thing you can do for all around durability.
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Jaxx on April 8, 2014
This is great work! What software do you use to create your plans?
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ultramicrobe on April 8, 2014
I don't use much software except for the actual drawing of the plans at the very end (Illustrator). I was thinking it might be useful to do a post on a simple 'software-free' way to design a plane. It works for me, do you think people would find that interesting?
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Jaxx on April 9, 2014
Definitely! That would be great for those of us who can't seem to find the time to learn how to use design software, but would still like to create our own designs. I would love to see how you go about coming up with the awesome designs you have shared with us.
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chadrat on April 9, 2014
Great project Patrick! I really like the 800mm solution you have... Great weight to power ratio. Everybody - I am the guy that catches the plane in the video, and I am really impressed with how the slightly smaller size of the power pod concept from FT really solves the problem of making small planes fun to fly. Strongly encourage FT to try some smaller designs - could be a good kit for them to cut out of all the spare foam from the full size builds!
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nerdnic on April 9, 2014
@ultramicrobe Just finished the Messer and this part "My planes needed a little trim because I make the tail really badly crooked." is by no coincidence. The plans are off for the tail section by a good amount. One side of the tail fuse is significantly larger than the other.
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ultramicrobe on April 9, 2014
Hi, Wow, you work fast! I had a look at what you found in the plans. sorry - I hate making plans. I think I see the problem. The ends of the fuselage were probably not meeting up right because the angle of the bottom wedge was not exactly the same on both sides. When I glue the tail together I just slide the sides up or down until the tail is in line with the wings, but this is hard if it is really crooked. What I did was re-post the fuselage page and in the new one I have copied the upper half and made the lower half by mirror imagine the upper, so the plan should now be perfectly symmetrical and less adjusting should be needed when gluing the tail. In any case, it made little difference to the flying, which I think is very forgiving. Thanks for the pointer, hopefully the fix works.
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nerdnic on April 11, 2014
I went out flying this morning and overall it does great in the air. It was very picky about GC, though. Once I got that sorted out I had a great time doing tight loops and acrobatics. I'm running a 29g motor with a 8x6 prop and it had enough power to do anything I wanted but I'm going to order a 50g like you've recommended.
Great job!
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ultramicrobe on April 12, 2014
Mine was also more finicky when I had the smaller 24g motor (that I burned to a crisp after one battery). Then with the bigger motor and 8X4 it was better, and now with the nice 9X6 APC and bigger motor, it does not care much. I put a heavy HK wing cam of Ed's on behind the cockpit making it WAY tail heavy and it still flew sufficiently well (the movies of it with the eagles was like that), but not well enough. Now I put a mobius over the back of the canopy, its slightly tail heavy but only a problem on landings. If I did THAT with the little motor, I would have smashed it for sure I think. I find anywhere even close to the wing-spar is adequate, but bang on the spar seems best (though I have to admit, maybe I have not tested this as well as I might). Go for the bigger motor and let me know how it goes. Love to see it in the air if you can post something.
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nerdnic on April 18, 2014
My messer took a heli pilot to the leg on a crash and ruined the wing. I decided to retire her and build a 800mm spit. I modified the ft plans using your to guide me. I also ordered the motor you suggested. It looks like your 9x6 might be too much prop for this motor though. I tested and got 16a and 180w on a static wot with an 8x6.

I'm taking the spit out today and also trying the new motor and I'll let you know how it goes!
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Drezed on April 9, 2014
Funny you should post this now, as I planted my 800mm FMS BF-109 this past Sunday. While it's one of the better fliers of the first generation line of planes, it can still be a demanding plane to fly. It's my guess the under-camber wing tips are playing a big part in your success, as tip stalling is the main issue with the "commercial" birds of this size. I run a 2826 1400Kv motor on 2s, with a 9x7.5 GWS prop on my FMS 109, with great results. What's the AUW of your plane?


P.S. Great work, by the way! :-)
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ultramicrobe on April 9, 2014
What is AUW? Weight? They are about 360g (without the battery). I did not remember to weigh them before I first flew and they have some extra glue already from the odd fix up.
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Drezed on April 9, 2014
Yup, "All Up Weight". The total weight of the plane, with battery. :-)

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randall_l on April 9, 2014
Great article ultramicrobe. Bigger isn't always better

All my swappables (FT and scratch) are between 560mm and 710mm and fly awesome compared to similar sized manufactured foamies.

It's mostly a matter of finding the right airfoil. Experimenting with KFm (KFm-7 and KFm-8 mostly) airfoils has allowed me to build a fleet (12 so far) of small planes that behave like much larger aircraft.

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ultramicrobe on April 12, 2014
Yes, I am sure that you are right (I really don't know anything - I just try stuff out and see what happens), and I would love to see some of your planes - have you posted any designs and how they fly. I am sure lots of people would like to see these even smaller ones that out-fly bought versions. When I started this one of my flying buddies said "small = bad flying", which I had sort of come to believe as well. I finished thinking of going smaller still to see what happens, but you already have ! Love to see the results and know what kinds of motor/prob combos they use and stuff like that.
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randall_l on April 13, 2014
I'm no better than you, I just happened to stumble on something that works for me.

I use traditional plans (mostly from Hip Pocket Aeronautics) and pencil them up for the power pod and Depron. My RC Groups blog (http://www.rcgroups.com/forums/member.php?u=362109) has most of my planes as well as the details of my power setups. I just finished a ~700mm swappable Junior that I'm hoping to maiden this weekend.

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Flynn on April 20, 2014
Great idea Ultra! I've been looking for a nice flyer to put some 800-1000mah batts in. Do you think these will work? Thanks for the post!
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ultramicrobe on April 22, 2014
I think that won't be a problem as long as you have a good motor/prop combo and these are 3S batteries. It was OK but anemic with a Hextronic 24g motor and 8x4 prop, so I am actually loving what seemed like an overkill combination outlined above. With your batteries you might save some weight if you can balance it ok and have great but shorter flights.
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ultramicrobe on April 22, 2014
I test flew the ME262 with EDFs last night in a brutal wind. Seems to work, but the conditions were awful, so it was a very short flight since i did not want to smash it up just yet. I did learn it's probably a mistake to maiden a new design and fly EDF for the first time in gusting 28kph winds, so that is a plus. Going to finish it off and try to find time to do a post about it.
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Oatman on May 14, 2014
Fabulous work! ... again. Thanks, I'm totally inspired. BTW have you tried the FMS 800mm series? (most of which are now actually 750mm wingspan for some reason)

The V1 desert paint 800mm (actually is 800mm) BF-109 by FMS is one of the best flying warbirds I've ever come across. It is a vice-less dream to fly. Twitchy in the wind, but no worries it is all bark no bite there. Won't tip stall, I tried. Glides forever. Just ditch the stock electronics at first opportunity. Once I bent the shaft rather than repair I just got a turnigy 200 watt 1400kv 2210 and a 25amp plush with proper 3.5mm bullets. Stupid power.

I'm torn between your 800mm 109 or the new FT Mustang... perhaps that one scalled down to 800mm as I love that size (for all the reasons you mention) ... great work and thanks again!
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Oatman on May 14, 2014
Oh, BTW ... the photo of the front looks like your thrust angle to the right is pretty extreme. Is that just a perspective exaggeration or did you really need to dial in that much right thrust?
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ultramicrobe on May 14, 2014
I'm not biased at all, but I would definitely build my mustang - ha ha. Seriously, I have not made or flown the FT mustang, but the one I posted (the full size one I posted last year) flies great and looks good too - check it out before you decide. I particularly like the fact that it makes a high pitch screaming sound when you dive.

Interesting to hear about the FMS, because two friends have them (Zero and Spitfire) and they were awful. So awful they threw them out. Maybe the 109 is just an easy shape to adapt to the size.

As for the thrust angle - yes it is the same as I use on larger planes (I use nylon washers as spacers between the firewall and motor mount - two on the upper left bolt, and one each on lower left and upper right to get down and to the right). I flew the 109 without any spacers and it was really going up and to the left. Put in some spacers and it flew straight as an arrow. I think the momentum of the 9" prop on that little airframe is pretty substantial.
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ultramicrobe on May 14, 2014
I just looked at the picture and the perspective does make the motor angle look crazy. It's not crazy, just angled like I said and like you would expect.
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Oatman on May 27, 2014
FYI ... The rulers on all these plans seem to still be 80% so 1 inch doesn't equal 1 inch but rather 0.8 of an inch. I measured the width of the power pod, motor mount template and fuselage and all seemed to be the expected 40mm. It also seems rather awkward to mix and match your units ... inches here and mm or cm there... come on, lets lose the english/imperial crap already, we're engineers no?
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ultramicrobe on May 27, 2014
Yes, they plans were shrunk and I never bothered to unshrink the scale bars, I thought it was not a problem but I you're right that would have been better. As for inches and mm, the whole design is already an awful mishmash of both - my guess is Josh does imperial and David does metric? so the spitfire was a mishmash, and everything derived from it more so. I do metric (because I am Canadian), but I don't want to put off readers who do Imperial. I guess if the International Space Station can function with both (NASA only went metric in 2007), we'll just have to live with it as well. All my plans from now on (I posted some today) are going to have both scale bars, metric grids, and the designs are metric. Either way though, the plane still flies, right?
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Hack73 on September 22, 2014
When I print out the plans, they look too small. What is the proper setting in order to print them out at 800mm? Mostly the fuselage.
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ultramicrobe on September 22, 2014
They are probably right. When I scaled them down, I forgot about the scale bar, so they should be 80% size too (so the 5 inch bar should be 4 inches)
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Hack73 on September 23, 2014
I was wonder if anyone can use these printouts to make more 800mm or FT planes?

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allenfr on October 28, 2015
I finished two of these planes. One was a P51 the other was the ME109.
I flew both yesterday and I used a take off dolly to run down the runway.
Both planes flew beautifully with no problems. Club members were very happy with the flying and I landed both in the grass with no probems. I used the 9 x 6 prop and they were fairly fast.
Thank you for the plans. Allen
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ultramicrobe on January 24, 2016
Hey, that is great to hear. These planes are still flying great for me. The smaller size is more durable. My 109 is particularly good, and they are really fast with a 9X6, which is what I used for all the vertical in the video.
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nicksta rc on March 25, 2017
could i shrink the 109 plans so i can have about a 24" ws 109 to chase my friends mini mustang?
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ultramicrobe on March 25, 2017
If you try it remember to take into account the thickness of the foam does not shrink, so that needs to be kept 100% in the shrunk plans. I think you will hit a size where performance starts to be sacrificed, and I think it is right around 800mm. These are only 6" larger, so I would either just build one like the plans say and fly it with your friend, or better yet, you could both make one of each! Good luck!
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nicksta rc on March 25, 2017
Ok Thanks for your imput!
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800mm Swappable Warbirds (that actually fly)