Tamecat

I have aquired a set of Model Airplane New Glasair plans. I size is o.k., but I am going to blow them up by 50%. I have never built a giant scale airplane before and would like suggestions, and advice from you model masters.

AmishWarlord

My Feedback: (5)

Hey if you can handle it go for it. But you might want to stick to the plans as is for the first one so you can gain some experience. After you build and test out your plane you can sell it to finance the building of 1/2 scale plane.

Keep in mind that this plan is for a plane with a 71" wing and using a 1.20 size engine. Your going to have to make a lot of structural changes to the plans for it to handle a big gas engine and it's tork and vibration. You don't build Giant scale planes like you do .60 size ones.

Tamecat

Actually the plans call for a .75 or .90 sized engine. This is not outside of my capabilities and I've built planes in this arena before from twins, trainers and sport planes. But something that is slightly over 50% in size over what the plans called for got my attention. Yes, you are right about the gas engine. That totally slipped my mind. I guess I'm looking at the building of such a plane. Two questions comes to mind I need answered: 1) how much does the averge giant scale airframe cost to build? ( forget radio equipment, engine, fuel tank & lines, etc.) 2) Are we getting into the area of building like a full scale plane?

Flyfalcons

Tamecat,
Are you saying the plane will be 50% larger than the plans call for? I think A.W. is confused, thinking you are building a 1/2 scale plane. If you are looking into a 100" wingspan, you are still in the 'comfort zone' of traditional construction techniques, though you will want to make sure the plane can comfortably handle a 60-70cc gas engine. Have a look at the plans in MA for the 35% Extra to get some insight as to the differences in construction between a standard model and a giant scale. Hope this helps.

AmishWarlord

My Feedback: (5)

Nope I'm not confused. You see the plane he's talking about is a small home built that has a wing span of 20 or so feet. So the model with a 71" wing is between 1/4 and 1/3 scale starting off. If Tamecat enlarges the plans 50% then the models wing span will be 106.5" or 8.875 feet. This will make his model just shy of 1/2 scale!

One thing is for sure, what ever size he builds it will be fast!

Tamecat

So guys are we getting into building a small fullscale aircraft?

Flyfalcons

The glasair has a 23 ft span. If he builds one around 8 ft or so that's just a little bigger than 35%. Either way it should not be confused with a 50% Extra or something. 100" is still model airplane territory.

Tamecat

Let's say for agrument sakes that the overall wing span is 8 feet plus (Don't know how the numbers will work out, but it will be damn big!) I'm wondering about the construction techniques. I read the article in MA. The wing platform is based on the full scale dimensions. But the fuse build up seems different. Solid but different. I don't know if I could use the techniques on this plane.

Tamecat

Flyfalcons

To answer your question a little better than I did previously, when going from a 72 inch span to roughly 100, you would be best off by taking the outline and redesigning the actual construction design. The Glasair is relatively easy because you can make a box fuselage and add a turtledeck to the top. In addition, you will want to make an engine box instead of using the standard firewall mount. This will allow you to transfer the load of the engine back a ways into the fuselage. As far as wings, you can cut foam versions or build up some using basswood spars of 3/8".

AmishWarlord

My Feedback: (5)

Yeah I agree. 100" isn't too bad. I'm thinking along the lines of going to a bigger eninge and ofcorse keeping that planes speed in mind.

Tame, I've looked at some construction pages of the full size aircraft and it looks like that thing is built more like one of our models than a "Real" airplane.


Oh did you see this tread on the Byron Glasair?

Byron]

Tamecat

Nope. I didn't even know there was a Byron thread. How do I get to that it? As for construction, Will I be alright if I use the blown up plans to construct the fuse? Or should I go the Extra route? The wings will be foam core. (As I aways say, Come home to foam!) I find that foam cores are easier and faster to construct than built up.
I'll have to study the engine box. Never did one of those before. I'm less hesitent on trying to do it now but I still need prodding. I'm concerned about the forces on the tail surfaces and how they would be attached to the fuse. On a smaller model, it wouldn't be a concern. On something this big, everything is a concern. Don't want to make a 25 pound plus bullet bomb!(flies really fast, comes apart in fight then crashes.) That's too much money to waste.

Tamecat

Flyfalcons

If you are making foam wings, then just go with foam tail surfaces as well. I have a couple NWHT planes that are all foam, and there has never been a problem with their tails. Just because your plane is big doesn't mean it's going to be a rocket.

AmishWarlord

My Feedback: (5)

Tame just click the link named "Byron" on the botom of my last post.

Tamecat

I never considered foam tail surfaces. Did your planes have sheeted over lighting hole?

Flyfalcons

My planes have solid foam wings and tail, capped with 3/8 balsa, sheeted with 1/16 balsa, and capped again with 3/8 balsa. The second cap allows sanding of the leading and trailing edges without compromising strength. They also have no dihedral brace and have held up well.

Tamecat

Wow and Double Wow!! To fly this plane, you have to fly it like a real one! I'm getting goose bumps. That's a great link. Thank you. I will do a little redesigning of the fuse. I like the Glasair III and if memory serves, the nose was lenghten just a bit. That would solve my trigear problem also. (I hate tail dragger!)
If there is anything else you think I really need to know, please don't hold back. I'm about to cut wood!

Flyfalcons

Since those plans were created Stoddard-Hamilton stretched the tail as well. www.newglasair.com will help get you started; have a look at the planes and see how they have stretched some. Pitch instability plagued the early versions, but the new ones fly very well. The stretch also makes them look better. Remember, there will be a number of differences between your plane and the Byron version, so you could end up with a totally different handling plane altogether.

GlasairRG

As a pilot of a Glasair IRG (well, sold now, but...) and currently building a Glasair III, just a quick question: WHAT pitch instability? Have you ever flown one? It's a high-performance plane, pitch stability is up to pilot ability to handle a short-coupled plane. Ain't nothing wrong with that aircraft. And they have all been built identical, from the first kit to the last.

Flyfalcons

Speaking with Ron Wantajia in person, he said to me how the early 1 model he flew was not easy to trim in pitch, and that the alt. hold autopilot could only maintain a 500fpm+/- ride when trying to hold altitude. That is what the S in the Super II-S model stands for; a stretch in the nose and tail. At least that's what I was reading in the factory of these planes. So to say that the plane is unstable in pitch may not be the best wording on my part, but S-H recognized a need for improvement in subsequent models.

GlasairRG

Well, and that all depends on your a/p. Century probably did have problems with Glasairs, but S-tec sure did nail-'em. Heck, I didn't even have an autopilot on mine but I had more trouble with yaw (see any airplane with no wing/fuselage break on the belly) than with pitch.

Flyfalcons

Did your plane have the larger rudder or original one? I'd have to say that behind the Beaver (of course), the II-S or III is definitely my dream plane.

Tamecat

Now now guys, let's not squabble over minor technical point of view. Like all new anything, there are always teething problems in the beginning. We all heard at one time or another never buy a new model car. Why, because they haven't worked out all the bugs. So we wait till the next year when those problems are addressed and fixed. This is all it adds up too. The Glasair was and still is ahead of its time and with each mod the plane improves dramatically. So there's no point in arguing over the beginning, let's look at where it is now. A great plane.

(OH MY GOD!! I'M LOSING MY CAFFEINE HIGH!! COFFEE, I NEED COFFEE!!)

Flyfalcons

It's all good; sharing of info is what debates are all about. I didn't view it as us at each other's throats. If you want squabbling, check out the AMA forum. You'll find plenty of it there.

GlasairRG

My Glasair had the original rudder

Tamecat

I read the article in AMA. Now is that plane built much like a homebuilt? Or a better question would be if I was to build my Glasair a little over half scale, the way they built the extra 300XL, would it be structually sound.