I have a GMS .25 engine do you think it could fly (sport like) the kobra?

I had a OS 25LA in mine at the start. Really long take off runs but once in the air it was fine. Replaced it with a ST G34, what a difference! Lept off the ground and plenty fast for me in the air.

Dan

So maybe the gms is adequate, at least in paper seems to run stronger than the .25 LA.,

Thanks Dan

I have a Kobra I modified into a tail drager. I used a Thunder Tiger Pro .36. The plane jumps off the grass and is faster than you want it to be at times(I must learn to throttle back)! lol

The fit is sort of tight but, it did not require any modifications to the plane to install.

I would recommend the Pro .36 for a Sig Kobra to anyone. [8D]

Beowolf, you think the .25 might be a bit wimpy? ,the reason for asking is that I already have that engine (.25) but I think I could try to get a tiger .36

The .25 should be just about right. This is one of those little planes that people tend to do engine over kill with. I built one for a friend for racing with a WEBRA .55 in it. You think wolf had a tight engine fit in his. I had to mount the engine, build the cowl around it then cut enough away so the engine could be removed if needed. It came out OK but it was a lot of work to get that engine in there. Then came the CG problem!!! When the pilot did the maiden on that little buzz bomb all he could say was, mite twitchy!!! Took a while for his knees to quit kinocking too.

I shoe horned a OS46 in, Grey Beard helped me with making it a tail dragger. This little plane would probably do fine with a hot 25, would be more balanced and light. BUT-a 36 to 46 or even that Webra 55-well smokin!! Gene you never said how that plane flies with the Webra??

I had an O.S. 40 in my Kobra. It was a rocket!. It was a lot of fun until the wing folded!

Just checked the sig website, they have norvels .40 for 75 bucks, they weight with muffler around 10.5 oz,light and strong Ill tryt one of those!!

I'm in the process of building a kobra and have a Norveel Ax-40 to put in it. A Fox 40 would be even be bit lighter.

We're talking about the Kobra, not the Kougar, right? 46 inch span, 3 pounds. I don't understand why anyone would think a strong .25 was too little. And I'm sure the GMS is a strong .25. Last I looked the AX-40 was close to 14 oz with muffler.

I always assume that people who have to ask have limited experience. And my response is always the same - what's wrong with the designer's recommendation? The guys who go out and happily fold the wings with a .40 aren't asking...they already have the experience to tell them when they are pushing it. Nothing wrong with doing that, but not the best starting point. Jim

Mark, it is a mite twitchy!!!!!! The .55 does tend to over power it a little. That little plane lifted off in a couple of feet and went straight up, needed a little trim then it took a bit of getting used to. Glad I'm not the pilot. My fear was it would go real fast on the straight and not turn around the pylons but just skid. It turned very well though. This is the first race plane I have built for this pilot that he ever has put EXPO in the radio. He takes off and lands on high rates but fly's on low rates. I did talk him into using the muffler like you have to remove some of that weight up front. The plane fully loaded came in at 3 pounds until I installed the engine then it hit 4 pounds. { I think, been a while} If I built one for me I wouldn't go any bigger then a .32, I say that because I have several of them and a few .25s under my bench doing nothing.

I agree Gene, I would do the same-32 or 36. Mine came in at 3lb-5 1/2 oz so it's within limits. I take off and land on high rates and fly on low just like your bud. Amazing little plane-Thanks again for the help with the tail dragger conversion.

I am about to start a Kobra build and have an Enya 40BB ready to go into it. (But then, I put Enya 40's in everything!) Should be a rocket. I had the same size engine in a Midwest (Foam) Attacker - which is a little smaller and lighter than the Kobra. A lot of fun!


My rule is look at the recommended size (19-25 or 19-35) and then stick in an Enya 40. Pretty simple rule.

Gotta remember, there's no such thing as too much power! Well, actually there is, a .90 would be a bit much!

I'm building a Sig 1/3 scale Spacewalker and with the 5.2 HP DL-50 I'm putting on it will be way overpowered, especially compared to the scale power to weight of the full scale. At a little over 2 HP it would have the same P/W as the max engine recommended for the full size (150HP).





Mike

Too much power is just about right!! On this build the problem was finding room to mount the engine, it gets a mite narrow on the fire wall!! Then the cowl has to be built around the engine and cut so you are able to do things like remove it if needed. It's the little things you have to think about. In this case I figure the pilot will be able to just walk out and pick the engine up after he digs it out of the hole!

Hi I just got a king kobra and cant seem to balance it.Can any of you guys tell me where it balances with a os 60.I know the plans say 3 3/8" but it is way to tail heavy.
thanks Fred