I have a stupid question....any trouble with your molds deforming under the pressure of the vacuum bagging? Maybe not since there's an equal amount of pressure on both sides of the mold?

John

flugzoid,

Yes, that can happen as the air is sucked out at different places at different times.

Made your mold strong!!!!!!!!!

Darrin C

Yes, good point. I'll have to keep that in mind to try and make them strong AND figure out how to prevent leaks. Thanks for the reply Darrin.

My mold is pretty strong, but I think it could be better. I've feared coming out the next day to see a crack in it. It also depends on the vacuum applied. I generally use less than 10" for everything, including most of my molds. 5" or 6" is plenty (more than enough!) for white foam.

Leaks are a major problem as the edges of the mold seem to puncture the material very easily. My homemade vacuum system cycles whenever it senses a 2" drop in vacuum. This bag (brand new) is leaking and making the pump cycle every minute. This bothers me as it is bad for the pump to do so a lot and potentially shortens its lifetime. Generally, I can get 10 to 15 min cycles. I think there are some small leaks in my system, but the bag is the most noticeable.

Michael

Mluvara

Did you trim the excess fiberglass flush to the parting line while it was wet before vacuum bagging it?
Also is there any problem with the bag sucking down at the firewall? That seems like a long pull.
I am going to pull out my plugs from my Edge molds today. The top removable hatch was finished yesterday.

Didn't cut the glass. It hangs over and then I can trim it before joining. I've got it down now where very little is hanging over.

Not a problem near the firewall. Hardest part for it to pull down is the scoop.

Hopefully, this will be my lightest fuse yet. I used only 11 oz of resin in layup and the best combination of glass/composites that I feel will work. We'll see. Probably won't even join the fuse till later in the week. I have three midterms in my engineering courses this week. Gotta lay off the models.

Michael

Nice job Michael. Good luck on the midterms too!

What weight cloths did you use, and how many layers did you use?

Layup from outside surface inward-

primer/3oz/misc reinforcement around wing mount, tail, firewall, & other areas/aeromat/3oz

Basically it's two layers of 3oz with carbon near the firewall, and areas of reinforcement. There's a strip of glass near the stab area, some on the fuse near the te of the wing, etc.

Michael

Mike,

just came across your thread. I am another one of the people you sent the reflex airfoil to. I am in the process of making plugs for a Q-500 using a thinned MH 18-B and a Q-40 design of a Caudron 460 with your reflex.

The guy that taught me how to mold doesn't bother to bag the fuse. It's a very similar process to what you have documented here, but we just lay up glass and CF in each half, trim the overlap while it is still green, with the exception of an inch or so all the way around on the second half to be layed up. This inch is then used to secure the two halves together once the molds are bolted together (wet lap) (instead of using tape). It's a much faster process since it all gets layed up molded and bolted together in one (long) sitting.

TiGuy
aka V-Raptor

TiGuy, What are the chances of getting some pics of your Caudron? I have been modeling that plane for many years. I even have a 15QMidget wing built, and a fuse plug made that I have never put to use (fuse plug is probably of too poor quality to use).
I would really love to see your Caudron, and would be interested in possibly getting a fuse and wing from you someday.

Matchlessaero

www.geocities.com/matchlessaero/

[email protected]

PS. Mike-wonderful info!!!! I have really enjoyed looking at your pics even though I will probably never be capable of doing what I have seen in them

TiGuy-

Let me know how it goes with the airfoil. I'll be interested to see how it does.

I've done wet layups on the Tsunami. It comes out good, but the benefit of using the composites and bagging is that I need NO other formers except for the firewall in the fuselage. Once the stab is mounted, that is it. Makes life simple. Granted the bagging takes a little longer, but seems to have some benefits.

matchlessaero - It's not as difficult as you would think. I only learned how to do it in the past two years myself. I caught on pretty quick. It's almost addicting.

Michael

matchlessaero,

All I have right now are the plugs in semi-primed form for the fuse, and the wing needs to be re-done (I made a big mess on the first one). The biggest problem right now is that I am in the middle of packing to move into a new house (where I get a 300 sq foot shop all to myself...woo hoo!) I'de love to show off what I have right now, but it is going to take some imagination to envision it in final form.

It is being built to qualify for approval for AMA 422 racing, so I have kept as much of the scale shape as I can. I blew up 3-view drawings to the fuse length I want (33") and then stretched the wing planform out to cover the needed 400 sq" required.

I just had my hands on it last night as I rearranged some things to go into "fragile" storage so it's not burried. Give me a day and I'll take a couple of pictures with a sheeted foam core wing that was the first prototype (I'm now on my third before it has even flown once).

As far as your fuse plug is concerned that you mentioned is probably too poor to use, as long as it is symetrical, it would probably be a great first venture into mold making, and once you get a fuse out of the mold, you can then massage that one for a second generation plug. I think this is an easier way than trying to get a complex design perfect the very first time. It may take longer this way...but it gives a more instant gratification rush! And you don't have to worry about ruining that plug that took months (years) to shape!

Go ahead and give it a shot...what do you have to lose?

Thanks for the encouragement ya'll!!

I may have to just break down and do it. I think I will wait until we (wife and I) get into a house first, a single bedroom apartment is a pretty awful place to glass the center section of a wing. I can't imagine how bad creating a mold and then using it would be.. I can't wait until I have a garage again!!!!! : )

I pulled the plug and wing out of storage back at Christmas. Even took some pics of it, I will post them if I can get them developed soon.
The plug is fairly symmetrical. I have some tools that will allow me to check that for sure.

I think a q500 fuse might also be a good experiment for learning plugmaking and layup because of the relatively simple shape.

Thanks again Mike for the neat posts, I know we all look forward to seeing the end results.

www.geocities.com/matchlessaero/

Just had to put up some pics of my plug. Carved it from solid balsa, and then resin'ed the heck out of it. The wing is from another Qmidget (15sized).

Ya'll take care......

Sorry for the lack of updates guys.. I went on a building spree when construction began two weeks ago because I had the time. Both my brother and I got very busy last week. So far this weekend we have mounted the stab and wing on the Tsunami. Still hoping to have it done for the race in Sacramento in three weeks. Hopefully, this will be a good week to make progress...

Michael

Lets see what this looks like posted. This is the plug for my Q-40 design.

Here's another sinister look at the nose. I designed this to allow the Nelson Q-40 muffler to be partially enclosed by the fuse down the centerline.

....as you can see better in this photo.

Tiguy, your Caudron looks great! Much closer to scale than the one I started. I cannot wait to see how yours comes out. Good luck in the move.


Mike, I also anxiously await seeing your Tsunami. I hope your finals have gone well!

No finals yet.... That's May! I took three midterms in the course of 4 days last week, so I halted all work. We're gonna go full throttle at it this weekend. I've mounted the stab and filled it in, along with doing minor filling in the last few days. will have photos this weekend.

Michael

Michael,

Looking forward to find out how the tsunami runs for you.

Matchless Aero,

If I had the option, I would do more non-scale shaping to get the fuse thinner at the tail, and a more streamlined canopy, but since my intentions are to get this AMA approved, I am very limited to what I can do and still get it to pass the commitee's scrutiny.

Once I get the plug completely sanded smooth and primed, I can send drawings/photos of it in for approval, along with 3-view drawings etc.,and if it passes, then I can make the mold. Then If I want, I can further shape the plug and resubmit it for approval.....and on and on until either I am satisfied, or the commitee says I've gone too far.

In the meantime of all that back and forth, I can fly the snot out of the first design and play with different airfoils, dihedral's etc.

The prototype will be flown with a Jett 50 which will give me throttle control and still give me a good idea of how it handles at speed (I'm guessing 140-150mph). That speed is well below Q-40 speed, but I need to start somewhere.

After all this talk about my pet project, I am all fired up to get back at R & D on this and get it in the air.

TiGuy,

I wouldn't worry too much about scaleness for Q40. The Sidewinder (aka TRC-1) was never even built in full scale. Take a look at the license taken with the drawings for the proposed full scale aircraft versus the Small Creations rendition.

Also, the P-51 variants are NOTHING like the full scale planes. If they were, any Miss Ashley/Vendetta would have a big nose designed for that huge Griffon motor with the contra-rotating props.

Make your plane look nice and sleek, and somewhat like the full scale plane and you'll be closer that the current dominators of the event.

Update from the Tsunami... here are pictures as of 3-10 at about 4:00 PST =).

Paint should go on next weekend

Race on the 24th, the clock is ticking!

another pic...