Chris7

hey,
i was wondering how much difference it would make, or how it would affect flight if i put a .25 in a .40 sized plane.

Chris

novabill

What plane is it.

Chris7

i was thinking of the SPADet

novabill

I think that would probably be too much plane for a .25. If you want a trainer, try an SSR with landing gear and add ailerons. There are also many inexpensive .46 size engines for under 100 bucks if you want to go with the spadet or deb.

William

Tattoo

On a calm day with a long runway it would fly if the .25 was a good strong bearinged engine. It would work for training as long as the trainer was skilled and didn't stall the airplane on take-off. Yes it would work, but not enjoyably. If it's an old weak or bushed engine, I would recommend not even trying it, as you would only be dissapointed.

Cajun

Tattoo, I've been helping a new pilot with a Deb look-a-like Spad flying with a OS.25 and I was amazed at how well it flies.

Personally I would never have tried it either, but I test flew it on it's first flight and now I would have no problem reccomending it if the plane was not way too heavy. A low wing loading is a necessity. As a trainer it's pretty good as the speed is slower but it still has enough power to get one out of a bind.

After flying the SSC combat class with .15s for a year my opinion on some of our old parameters has changed. Flying a plane on the wing is fun.

Cajun[8D]

Tattoo

I can agree with a little experience, as I flew a BUHOR at 5 pounds even with a Mag .25 Xl and I was shocked at it's performance! However, it took a lot of runway to get off, and I really had to hold back on the climb out to not stall it. Once to altitude, it was a dream to fly and would be a GREAT trainer. Although it flew good, it could have gotten a beginner in trouble, especially on a windy day on a take off turn down wind. Also, the engine had to run strong or forget it. So yes it can be done. Even aerobatic were possible, but, experience and power managment had to be used. I will add one very positive note to this, and that is gas mileage. The Mag .25 would run for almost 45 minutes on the 10 ounce tank I had on the plane[8D] I based my answer on this experience, as the Spadet ready to fly weight will be approx 5 pounds with roughly the same wingloading as a BUHOR (although the Spadet is a MUCH better looking airplane)

rlt55

My GMS .32 is the same size as a .25 but runs more power.
I put it on a SPA3D and cut the wings down to 30" with about 34" of fuse.
It ZOOMs, so I'm almost sure it would fly normally/slower with a .25 on it.
Like the man says, you never know until you try.
Weight is 3.6 lbs.

FrankC29

Interesting thread. Usually the queation is "Can I put a .90 on a Spadet"?[X(]

If it's a lightness issue, and you do not have an engine yet, you could try one of the .30 size engines, which weigh the same as a .25. I think a OS32 or TT36 or similar would do the job well and save you a good 5-6 oz. A good strong .25 like an OS25fx or Mag 28, maybe, but I can't imagine it would be a whole lot of fun. A .25 LA forget it.

Cajun

Frank, I agree, it has to be a good .25.

The ship also has to have a low to med. wing loading, and dihedral. A 5 lb. plane with a 24 oz wing loading and a flat wing sure wouldn't qualify.

Cajun[8D]

3d-aholic

My Feedback: (7)

In my experience you cannot compare a .32 to a .25...especially if the .25 is bushing and the .32 is BB. Not sure what kind of .25 this is. I've put those little .32 BB engines in .40 sized planes, dropped the overall weight, and proped the engine to outperform any bushing .40. If this is a bushing .25...they tend to be much lighter on the power side....and even if you whine out more RPM, they won't pull a very big prop.

Just look at the stats though for a .32.
[hr]
GMS .32 BB
Output: 1.2 BHP at 18,000 RPM

OS SX .32 BB
Output: 1.2 BHP at 18,000 RPM

GMS .40 BB
Output: 1.25 BHP at 15,000 RPM
(a mere .05 BHP increase and a loss of 3,000 impossible to get RPM's)

OS LA .40
1.0 BHP at 15,000 RPM
(a loss of .2 BHP as well as a drop of usable RPM's)

Most .25's are half of the .32.

So, you see that there is very little power increase going from a good .32 to .40, and sometimes, there is a loss. And, I realize these stats are untainable circumstancial...but everyone is cheating equally so they are comparable.
[hr]

Most planes will fly with less power...but there is an eventual cross-over point where the "less power" requires "more skill" to keep the plane flying and out of trouble. Harder is good....too hard is a pain. I'm building a Spad3d-40...but I'm not sure I would put a 25 in a 40 sized plane....and I'm on record as not power crazed (most of the time). I'm sure it will fly...but it will take a lot of unnecessary work to keep it so.

Chris7

the engine in question is an O.S. MAX 25FX

3d-aholic

My Feedback: (7)

I can't believe I'm arguing for more power.

So its also an older engine then too...and probably no longer running at peak performance....that makes it even harder.
Your looking at around .80 BHP at 18,000 RPM at around 9 ozs. spec'd and you probably won't come near that.

A new OS 40 FX is rated at 1.36 @ 16,000 at around 13.6 ozs. Nearly twice as much. That plane actually suggests a 40-46....

You have to build extra light (the wing is suppose to be using 2mil coro anyway). You have to set your control rates very low and milk-it most of the time. Use all the runway, don't make any sharp turns, do all acrobatics with a running-start..and only simple ones at that. No climbing in turns. Don't fly in a stiff wind. It would probably stall in a heartbeat. To many folks, these issues would be described as miserable (un-fun)......but I don't know your budgetary conditions or what your threshold for "pain" is.

If this is your first plane, I wouldn't do it....you might get a bad taste for the hobby and give up. When your starting off, there are too many things stacked against you anyway....adding a very unpowered plane....makes a steep curve. If it were your 10th plane, then maybe your pushing the envelope and trying to see how low you can go. I've built planes who's primary purpose was to see how fast it would go until it disengrated, how slow it could be before it could be called a glider, etc....but then I get bored easily.

(BTW, this is only an opinion...there is never but one way to find out)

ChrisSpad

the other consideration is balance. Chances are, you put a 9 oz engine on the nose of a plane designed to have a 17 oz engine on the front, your gonna need 8 oz of lead in the nose to balance. Your weight advantage disappears. You could lengthen the nose out 2 or 3" to help compensate, but, your adding weight that way as well (but nowhere near as much as adding 8 oz of lead to it).

Long story short, can it be made to fly on a 25? Probably. Will it be fun? nope. Will it work as a trainer? not very well.

Cajun

2much, your puttting way too much emphasis on HP. HP is meaningless in this issue. In fact it's meaningless for any purposes other than mfg. hype.

I just returned from the field where my new pilot had his OSFX.25 powered deb look-a-like
Spad out and I am still amazed at what it will do. Overproped with a 10x5 prop it was turning 10,200 RPM and was very quiet. Now I don't know what the HP of this combo is, and don't particularly care. Take-off runs in too tall grass were about 60', with great climbout. He did big open loops, rolls, inverted flight, and tried a knife edge, but didn't have enough fuse side area. All of this with a low time pilot.

Normally we wouldn't use a 10" prop on this engine, but he was out of 9". So we discovered something.....an OS.25 will pull a 10" prop with authority.[X(] Yep, blew my mind, and it sounded great. Will all FX.25s do this,,,damedifino

Just goes to prove, we never know till we try something. We can read HP figures all day from a book, but untill you have strapped the engine on a plane and flown it you know nothing.

I'm not saying ALL 25s will successfully fly ALL five lb. planes, cause they won't. But don't be afraid to try some of these smaller engines on larger planes. If the planes are designed right, have good clean airfoils, and low wing loadings you might be surprised. Now, if your flying 3D, forget it. But some of us have better things to do)WHOOPS,,,BETTER NOT GO THERE BILL[>:]

Like Frank said, this is an interesting thread as most of us are usually going the other direction and overpowering our ships. I guess this is why after 40+ years I still enjoy this hobby There's always more fun things to learn

FrankC29

Chris makes a point. I'm not sure where components are usually located on a Spadet, I haven't built one, but you might end up either adding nose weight or having to put everything under the fuel tank![X(] Remember this is a Spadet, you can't just move the wing around!

novabill

chris7
If you like the spadet, just scale it down a-bit and figure out ways to save a bit of weight. Try 75% or 80%. Take all the dimensions and multiply by 80% and make a drawing of each peice. Make sure the scaled down fuse has enough room for your radio equipment (if not, make it wider). Use super-light foam wheels and watch the weight every step of the way. If you have'nt already bought your radio equipment, buy lighter servos like GWS Mighty Micros and a AAA NiMH battery. You can probably get it down to less than four pounds(maybee 3.5). This would be a fun project for you and if you need any help with the dimensioning, I would be happy to help.

WILLIAM[8D]

red_guy

good question,

i asked the same thing a few weeks ago and the answer was the same.

i want to put a magnum 28 xl (NEW and with ball bearings) in a spadet.

but, since my time is so limited it took me quite some time to build it. fortunately it will be airborne on sunday. my plane came just over 5 pounds (2 or 3 oz) and i am planning to hand lounch it down the hill. at my flying site there is a steep hill, so that should solve the LOOOOOOOOOOOOOOOOONG runway problem

well, a 28 is a little better than the 25 engine and has the same weight, but a 25 should do as well.
the magnum is very cheap, but if i were to buy a small engine for the spadet i would definetly go for a thunder tiger pro 25 (the tt pro will smoke the magnum, but the magnum is low on price)

hope i helped in some (any) way

Chris7

Thank to everyone for all your help. William, I think i will give scaling it down a go and will give you a yell if any help is required.

thanks again

Chris

Chris7

One other thing, does anyone know of any spad cessna's or plans for them?

Chris

Throttle

Hello, I been flying a 40 size plane with a OS 25 FX for about six months. I call it the Debsulator. The dimensions are the same as the Deb except for the wing which is a RNAF and is 2 inches wider cord wise having no dihedral the tail fins and wing are mounded on a rail. The rail is made of electric fence insulator post. When I started this project I found the insulator post would bow where the wing was mounted and it would also warp in the sun light. So I got with Cajun to help me solve both problems. If you look at the photos you will see that we inserted a T beam which Cajun made from a yard stick into the fuse. While this add some weight to the plane it stopped the warping and bowing. The only holes that were add, were for the dowels and where the engine mount attached to the insulator post. There were no opening cut for the battery or receiver. The Debsulator has the receiver mounted internally in the fuse the yard stick falls about 4 inches short of being full length and leaves a space up front just behind the engine. The batteries are mounted externally just behind the engine, underneath the fuse. All wires are run internally in the fuse except for the ailerons wire, which was not long enough to reach so I had to run it externally. While the yard stick did add some weight the small amount of drag offered by the insulator post more than made up for it. This plane makes a great floater. The weigh was about 5 lb. On it maiden flight I let Cajun take her up (believe it or not he is my test pilot). He did slow roles flew inverted and did an out side loop. Yes it struggled on the outside loop but it made it. I enjoyed this plane and now have move on to a Debut using the electric fence insulator post for a fuse and the fuse is the same length as the Deb. But everything else is Debut. with landing gear added. A report will be up Coming for the modified Debut.

I hope this information helps encourage trying new ideas etc.... I want to thank Cajun for his countless hours of help and encouragement.