MARK JR

Hello, I have a sig kadet senior with no engine. I'd like to know if I can put a 15 cc gas engine on it.

jetmech05

Yes I'd think so

52larry52

My Feedback: (1)

MARK JR, You had better check (measure) the cowl length on your Kadet before commiting to shoe horn in a large engine. For the overall size of the plane the engine compartment is on the short side. As others have correctly told you the Kadet doesn't require a big engine to fly well, however it will need nose weight to balance so a slightly larger and heavier engine is fine. By "slightly larger" I am saying .91 four stroke , .60 to .75 two stroke, or 10cc gas. In any case, you will be limited by what will fit inside the cowl. Your idea of using a Saito 1.20 or a 15 cc gas is a bad idea, rethink it !

MARK JR

Thank you

MARK JR

How about a Norvel .40 gas

52larry52

My Feedback: (1)

Another issue that will come up if you go with an over the top too large engine will be prop clearance. A larger engine will REQUIRE a larger diameter prop and at some point it won't work without a different (taller) landing gear/ wheel combo. Do a lot of measuring and thinking before you decide.

52larry52

My Feedback: (1)

Not at all familiar with a Norvel .40 gas.

egldriver

I put a DLE 20 RA on mine to test 3 blade props for my 94 inch span P38. A master airscrew 15 7 turns 8000
A 16 8 turns 6300. Both seem to perform about the same. The maple mounting rails go all the way back to the cabin bulkhead. 1/8th lite ply bulkheads with balsa triangle reinforced. Originally it had a .46 glow then .61. Had a pound of weight to balance. Balance now perfect with 20 RA and no nose weight. Receiver and ignition battery under rudder elevator servos. Weighs 9lbs. Replace the nose strut with a Fults dual strut. 4 1/2 inch main tires. 3 inch nose wheel
Make sure the wing bolt block ine fuselage is glued good. Mine was loose.
A 16 7 or 8 2 blade will work on the,20. A smaller gas engine would work fine too

egldriver

Here it is buttoned up. Didn't bother with the cowl. It could be done though. A 15 with mount s to the firewall would be easier. Reinforce the firewall with triangle

MARK JR

It looks great

MARK JR

Egldriver, how do you reinforce the fire wall with triangle? Thanks

egldriver

Notice in the,first picture the small pieces of triangle balsa glued to the beams and firewall. Cut pieces of triangle balsa the full height and width of the firewall. Glue these with epoxy to the inside corners of the firewall and fuselage sides to make the firewall strong enough to support the gas engine and stronger nose wheel strut.
I just cut a hatch open like u see. The windshield is secured with screws to allow the hatch to be removed. Two screws at the front of the hatch hold it.
The ignition module is in front of the tank on foam rubber

egldriver

This photo shows the hatch support rails on each side. The small plywood blocks in the front corners for the hatch screws. Note that I used long maple rails to mount the engine. If you use mounts similar to the stock ones,that is where you would reinforce the firewall from the inside corners described in previous post.

2walla

My Feedback: (10)

An evolution 15cc is the same size as a 60 glow motor. I have an early one on my flying king. the pumper carb should have fixed most of the issues... The early versions relied on muffler pressure and the muffler was a p.o.s. and would vibrate apart every 2-3 flights causing a deadstick. I ended up putting an os 91 muffler on it and no problems since. I would go with the dle20re and move the servos aft if it looked like it would be nose heavy. With the 78" wing it will carry the weight. And you can always run a three blade prop. The re motors are a very clean install and u would end up with the upper cowling unmolested and the exhaust dumping well below the fuse. I wouldnt go wild "beefing" it up. The sig airframe is plenty strong to begin with and you most likely would just be adding unnecessary weight. Good glue joints and a small bit of tri stock is enough

2walla

My Feedback: (10)

Another note. I would stay away from the smaller say 10cc gassers as the rod bearing is relly small and most need 25:1 or more oil. Saitos are the same way. Lots of oil. If you only have ome plane it isnt a big deal, but i dont like having two cans of gas with different mixes.

JohnBuckner

My Feedback: (1)

Yes off course you can and as I noted on your other thread of the same subject It is an ideal combination for the cadet senior wheels or floats.

In my case I built it from a cadet senior kit and use the OS 15cc spark ignition version a superbly reliable engine to date.

John

52larry52

My Feedback: (1)

Gentlemen, I would like to retract my earlier thumbs down on using a 15cc gas engine in a Kadet Senior. As 2walla points out, a 15cc gas is equal to a .60 size glow engine. My brain must have been "out of gear" at the time as I was thinking it was equal to a 1.20 glow engine. I had it wrong. The extra weight of any of the discussed oversized engines is not the problem. The Kadet Sr. is inherently tail heavy and needs lots of weight up front to balance, so the old theory of adding nose weight with a bigger engine works here except most of them won't fit in the cowl. If you're going "cowless" then it works. If you are like me and must have that finished look of a nicely done cowl, then fitting bigger engines into a cowl limits how big you can go. For sure, a stock Kadet Senior will fly very well with a good .46 two stroke. Just last month, I passed on my stock Sig Kadet Senior ARF, that was flown for years with an O.S. .46 FX, to one of my fellow club flyers that needed that airplane to match his flying level. He returned my .46 FX and is powering it with a .55AX. It still flys great and he is a happy camper. To replace my missing Kadet Senior, I went to the boneyard in my shop and dug out a rejected Nitro Planes Super Senior ARF (Kadet Sr. knockoff) that I got from another Club member after he striped off the covering and realized what a POS it was. He was smart, he dumped it ! I was stupid, I followed through and reinforced, repaired and modified it. Lots of time, glue and additional balsa and plywood. Anyway, I completed it this past weekend and will maiden it next Sunday. How does that tie into the Kadet engine size question? I have a large inventory of .60 to .90 two strokes and .52 to 1.20 four strokes to pick from building this project. Yea, I wanted something more powerful than the .46FX in this one as I knew it was going to be heavier and I will add floats in the future. So, the only engine in this group that would fit inside the cowl (length was the problem) was an old K&B .61 with a slimline pitts muffler that I had. It fit in over 90 degrees with the cylinder head sticking out the right side for cooling just as nice as the O.S. .46FX had in my old "real" Kadet. My old Sig kadet weighed somewhere around 8 lbs RTF. The knockoff with reinforcements and mods came in at a whopping 11.0 lbs RTF. It's a TANK ! It required 1 lb 3 oz of lead to balance at 30% of MAC. Wing loading is still only at about 21 oz/ft2, so it should still fly well with that big flat bottom wing. Yes, I could have benefited from a heavier/larger engine but the K&B .61 was the best physical size for the finished goal of the project. The maiden flight this coming Sunday will tell me if struck a good compromise on this plane or if I missed the mark and it is underpowered. I'll let you know.

MTK

The OS 15 cc gas engine would make a good combo. It is super runner and is very quiet on its muffler. It puts out decent power turning a14x8 APC at about 8800. That should do fine for a KS. I have mine on a tclip but had to stretch the tail to accommodate.

it tends to be a little on the heavy side so make sure you can balance the model with minimal or no extra weight added.

another possibility is a 10cc gas engine. I read that the Evolution 10 cc, current vintage, runs well and is quite a bit lighter.

Gas mileage of the OS is terrific. I have an 8oz tank in the tclip and it runs at least 20 minutes. I have yet to run the thing dry. I also use and highly recommend the Tech Aero IBEC to power the ignition.

JohnBuckner

My Feedback: (1)

Larry I have had considerable experience with the clone 'Super Seniors' which occurred when Sig had their problems with CMP and for some time Sig could had nothing to sell but CMP sold considerable numbers of the Super Seniors with a much cheaper hardware package including useless pushrods and etc.

It was during this gap for perhaps a year and a half that I was running a popular series of pylon races (I think there were six over three years) Just for Senior Cadets any version kit, Sig ARF or the clones Super Senior and the world models Super Frontier version.

The Super Seniors were drastically cheapened and started to come in heavier and heavier with the heaviest I ever weighed was 11.5 pounds. I actually had the opportunity one time to weight the tail feathers (fin, rudder, horizontal stab and elevator with no hardware) but covered just as you would remove them from the box, of both the replacement Sig arf when they got going agine and the feathers of a Super Senior. I do not remember the numbers but do remember the Super's weighed in over twice as much as those from the Sig!

Now rest easy Larry I think you will be happy with your Super even with the extra weight they all flew fine and the sixty one is a good choice. There were a large number of them at one time in our club and none could be called anything other than a cadet even with the extra weight.

Heck I think I have powered senior cadets with just about everything from an OS 35AX all the way to 13 pound thrust Kingtek turbine and loved them all.

John

JohnBuckner

My Feedback: (1)

Now this is an overweight Cadet Larry

Engine OS 55AX, payload eight pounds of deadweight sandbags at the center section. While it was no aerobat the airplane flew controllably in a reasonable fashion, a successful experiment.

MARK JR

How much runway did you need for takeoff

JohnBuckner

My Feedback: (1)

Mark that required about 400 feet with a light winds down the centerline, runway length is 900 feet.

Here is another variation that required no runway for take off, No landing gears at all just some balsa strips taped to the bottom for landing:



John

born2build

Why would you want to put a 15cc gasser in this airplane? I have this kit in my inventory along with a Saito .62. The recommended engine size is a .29 to a .40 2-stroke glow. or a .35 to .45 4-stroke. This bird is designed to fly on the wing, not on the prop. I've looked at the replies to this thread and am amazed at what some of you are doing to this wonderful airplane. For comparison, a friend of mine had a Senior Telemaster (nine foot wingspan) with a Saito .91 for power. He asked me to test fly it for him as he was too nervous to fly it himself. The airplane flew great (of course!), The engine preformed flawlessly (again, of course!), but there was a problem. I could not slow the thing down enough to land! We tried lower pitched props. We tried adjusting the idle as low as we dared. The only way to get the thing down was to kill the engine on final. Unacceptable. The solution was to swap out the .91 for the Saito .82. That did the trick. A perfect match of airframe and power plant! Loops from level flight were effortless. Verticals were tall enough for nice stall turns and wingovers. And landings were a thing of beauty. Remember, this was a 9-foot Telemaster! It could maintain altitude with the throttle cracked open just above idle. Touch-and-go's were especially fun. Low and slow fly-by's down the centerline took forever. One guy even complained (with good humor) I was tying up the runway for too long. I guess what I'm trying to say is, you could do better than to simply stuff as much power as possible in an airplane, especially something like the Kadet Senior.

MARK JR

John, do you launch that plane?

MARK JR

15 cc engine is a .60 right