My 9 year old wants to build her own plane, so we started on a SPAD trainer today. I am building it sort of per the BUHOR 25 plan, but enlarging it a bit. I am also adding a coro fuselage to hide/protect the radio gear and fuel tank, and to raise the wing up a little higher for better stability. Make sense?

So far we have the coro fuse, aluminum channel, engine mount, and wing pretty much fabricated. Right now, the wing span is 72", but the spar is shorter, so I'll probably trim the wing by 6-8". I'll see how stiff it is after it's all done and mounted. The wing is 2mm and the fuse & ailerons are 4mm. The tail will be built per the BUHOR 25 plan using 4mm.

I'm thinking that we will power it by a .32 BB engine, maybe a Magnum. Maybe even a .40LA. I am shooting for a nice, slow, stable flyer, suitable for training a 9 year old.

I am going to swipe the servos from the SPA3DT I started. I'm going to shelve that thing for a while.

I think you're going to need something bigger than a .40 LA. I know you started out with the plans for a .25, but you've made the wing bigger, added a fuse, and I'm hoping you enlarge the tail feathers as well. It will take at the minimum a .46. If you make the wing bigger, the fuse needs to be longer and tail feathers need to be bigger. All that adds up to extra weight. I have an excel spreadsheet called design.xls that I use when I'm enlarging plans. You can look it up on the net or e-mail me and I can e-mail it to you.
[email protected]

that looks good. you will probably need the 46 size engine. I am flying the debonair. it has a smaller wing. but it sure is indesctructable. have fun, Im forgeting about balsa right now.

first.... If your going to enlarge the wing, you need to enlarge the tail, and fuse length proportionally. Second, on the fuse - pick one. You don't need both the angle and the corofuse, its overkill. Third, the difference in stability of a high wing coro fuse, vs the aluminum channel is negligible. While there is some pendulum effect, the difference isn't enough to be noticable.
I'm not trying to be negative, but, your changes, while looking good on paper will most likely result in a plane that won't fly nearly as well as one built by the plans.

Thanks for the input. The larger engine does make sense, and there really isn't much of a price difference. I did scale up the tail a bit as well.

Here is everything dry-fit to show it's proportions. I'll weigh it after all of the gear is installed, minus the engine, and then we'll decide which engine to put in it. The way I'm mounting the fuse onto the rail, I can slide the whole assembly to correct for CG at the end.

Chris,

Thanks for your input. If you don't think the coro fuse is worth the bother, then maybe we'll ditch it. So far, following plans have worked out much better for me than making it up as I go

I appreciate the advice.

It might be the angle of the pic, but that fuse looks kind of short. A typical trainer with a 60" wing span should have roughly a 40" fuse. According to my excel program, a 72" wing would call for a 50.4" fuse, a 19.5" horizontal stabilizer and a 9" vertical stabilizer. It says a .45 will fly it. a .46 LA with a 11X5 prop would drag it around just fine for a trainer.

Yes, the fuse is too short for that wingspan. I need to pick up another piece of channel and cut a longer one, and I am going to shorten the wing to 60 inches.

Thanks.

Just build to the debonair plans. You'll be very satisfied. That's what learned on, and the plane is still flying. I use it for AP now.

Brad

i love my deb!!

Check out this site for design calculators. I find them very useful when designing and building from scratch.

http://www.geistware.com/rcmodeling/model_calc.htm

Nice wing! that size is close to a SPADET wing. take a look at those plans and modify your fuse to match. I think you are spot on in the wing. I have built a simular one for my nieces. I used the fuse building method That a SWIZZLE stick has and spad wing almost like yours. Here is a pic and it flys very slow and gracefully as you would want it to for a youngster. This plane has 2 pine door strips for fuse and a 1/4" balsa wing box with all the goodies in it. conventional balsa monokote tail for lite weight. the wing box wasn't glued to the rails until balancing time just like most spads.

Thanks. Progress has been a bit slow lately. It's hard to motivate a 9 year old to finish a project that she won't be able to use for 5 months.

We have mostly been gathering pieces, and we pretty much have everything now. I decided to try a Super Tigre 40. I have had good luck with my ST 45, and the ST 40 is only $49.99 and I had a $10 coupon code for Tower. I picked up a radio yesterday, JR Sport S400, same as in two of my other planes. I went with JR Sport because their servos are slightly narrower than Hitec and Futaba, and will fit into the 3/4" channel. I also have 3 other JR boxes to buddy with.

I have extended the fuse to 42". I am leaving the wing as-is for now. I'll bring a pair of scissors to the maiden flight, and I can trim a few inches off each wingtip if need be.

I'll post some pictures when it gets closer to finished. Thanks

We have made a little more progress on the trainer. We are going to leave the coro fuselage on for now. It only weighs a couple of ounces and we like the way it looks. It balances right on the spar as-is. We just need to install the radio gear. The only thing I don't like right now is the center of the wing. I think I am going to replace the yellow strip with a wider one that covers the whole rubber band area and wraps under the front of the wing.

I don't have a scale that can wiegh it, but it's definitely lighter than my Alpha 40.

Seeing these pictures, the horizontal stab seems a bit narrow. I think I need to make a bigger one.

it looks like you need a 45 degree cut off the bottom of the rudder to allow the elevator to come up fully.

Thanks. I'm sure I would have noticed that while setting up the linkages . Good eye.

Here is the finished trainer. All we need to do is break in the engine and fly it. We are hoping to get it in the air this weekend.

My daughter designed the trim scheme. The underside of the wing has diagonal blue stripes.

I still haven't been able to weigh it properly, but I think it's between 5 and 6 pounds. Just about the same weight as my Alpha 40.

Mclina:
Nice looking SPAD - I like the bright colors. Best of luck with the engine and with the maiden flight.

Smooth

great job mclina!! i bet it flies better than expected! you might make that horizontal stabilizer a little wider and flex your ailerons upwards slightly.. when i did that to my spad it made it a completely different plane! it was overly touchy and i couldnt get it trimmed properly, almost like the cg was off, but when i shortened the aileron pushrods slightly to where the ailerons pointed up slightly it now flies like a dream!

your plane looks super! i hope you can get her hooked so y'all can have many happy hours together! if she gets hooked, keep her interested in planes as best as you can afford, thats the best way to keep her away from the boys is keeping her interested in something such as this where you can spend time together! a daugther needs her father close, when he is there with her everyday she isn't out looking for a male to be in her life cause she already has the most important one right there.. sorry some of those psychology classes i have been taking are shining through.. good luck with the plane!

Thanks fozjared. I do probably need a wider stab, but I'll see how it flies first. Yeah, I am hoping to keep her away from boys for a few more years.

I just ran a couple of tanks of fuel through the engine. It runs great. We are supposed to have 50 degrees on Sunday, so that's the planned maiden. I already added a set of skis. It has been in the single digits for a few days, and this weekend is supposed to be beautiful.

I don't know how many rubber bands you're planning on using, but in the pictures you only have a couple. Make sure you use at least 12-14 rubberbands to hold the wing on.

If you haven't already, you may want to glue some bamboo skewers into the leading and trailing edge of the wing wrap. This will keep the flutes from crushing, which they will do when you get that many rubber bands on.

Brad

Yeah, there are about 10 on it in the pictures. It will get at least 14 at the flying field. I have pieces of coat hanger in the flutes of the doubler.

The plane looks good. If your CG is setup right, I see no reason that it shouldn't fly great.

Here's someting I've learned about rubber band wings. Never put any fewer rubberbands on the wing than you plan to fly with. I once put 4 bands on my DPS just to hold the wing on for a CG test. Two days later I took it to the flying field that way and actually took off and flew it with only 4 bands. I realized I had a problem when I could see the fuse slap back up against the wing at the bottom of a loop!

We maidened the SPAD trainer yesterday after our winter fun fly. It flew just like a trainer. I need to make some adjustments to the control throws, since she is using a non-computer radio, but other than that, it flew very smoothly.

I was a little worried that the ST40 would not be enough engine, but that is not a problem. I was using the recommended break-in prop, 10x5, and it was climbing at 1/4 throttle. On the first landing pass, I had the idle set about 1-2 clicks high, and it floated right past me like it didn't want to come down. I lowered the idle on the second pass and it settled right down.

Unfortunately, we didn't get a video of this flight, but we'll get one next time.