Aloft Forums
Welcome to Aloft Forums. Register a free account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members through your own private inbox!
Hobie Hawk Restoration
- Thread starter Konrad
- Start date
Glenn Beer
Active User
The original paint prep was to sand the pod in order to bring out a faint fuzz. Then to quickly singe the fuzz to melt back the tips of the fuzz into balls. That provided the tooth for paints to stick.
As to fitting the wing root. If the gaps are small, I’d likely sand the root to fit the fuse, instead of trying to move the rods/holes.
As to fitting the wing root. If the gaps are small, I’d likely sand the root to fit the fuse, instead of trying to move the rods/holes.
Konrad
Very Strong User
Actually the flame polish is to set the electrical charge on the surface. This is lost very quickly like in 15 minutes or if the surface is touched (grounded). If one is looking for mechanical teeth for the paint it would have been best not to the flame polish the surface. But that is generally not the issue with Polypropylene
With the age of my pod the fuzz did not melt (ball up) with the torch until the base material distorted.
Moving the wing rod is done to maintain the fuse to wing root wrap around we love in the HobbieHawk look. And to remove some of the gross nose down rigged into the original fuselage.
I want to maintain a bit of nose down rigging as this defines the esthetics of the Hobbie Hawk in flight. While I think Nolan's mods are a move in the right direction for a performance ship. The Hobbie Hawk is the wrong ship to try to turn into a performance ship. His mods appear to have lost some of what I think make up for the Hobbie Hawk esthetics and that is the wing to fuse junction. I think the aft fuselage kink will allow me to keep the esthetic wing root and get rid of that gross 6°+ decalage. I still think I'm carrying far too much at 2°.
All the best,
Konrad
With the age of my pod the fuzz did not melt (ball up) with the torch until the base material distorted.
Moving the wing rod is done to maintain the fuse to wing root wrap around we love in the HobbieHawk look. And to remove some of the gross nose down rigged into the original fuselage.
I want to maintain a bit of nose down rigging as this defines the esthetics of the Hobbie Hawk in flight. While I think Nolan's mods are a move in the right direction for a performance ship. The Hobbie Hawk is the wrong ship to try to turn into a performance ship. His mods appear to have lost some of what I think make up for the Hobbie Hawk esthetics and that is the wing to fuse junction. I think the aft fuselage kink will allow me to keep the esthetic wing root and get rid of that gross 6°+ decalage. I still think I'm carrying far too much at 2°.
All the best,
Konrad
Last edited:
Konrad
Very Strong User
Seeing how Wayne's orange Hobie Hawk was fly at Sunset reminded me how much I like to see the Hawk fly and at the same time how much I don't like how the Hawk flies.
Last time I picked up this project I was filling in the low spots with epoxy filler (blue). I tried to flame polish the front pod without damaging the filler. I wonder how the OEMs did this as they used a lot of filler to blend into the tail cone and to fill in the belt sander marks from the removal of the mold part lines.
I put down a coat of Shop Line PPG primer and let it stabilize for close to a year.
(That's my story and I'm sticking to it!) I block sanded this coat to the state you see now. The primer has stood the test of time and my sanding block. I still have a few low spots to build back up with primer.
I'm wondering with the OEM filler issue how much validity to give the flame polish process.
As this PPG Shop Line primer is a catalyzed product I'll wait until I have some of my other F3F ships ready for primer before mixing up a batch.
Last time I picked up this project I was filling in the low spots with epoxy filler (blue). I tried to flame polish the front pod without damaging the filler. I wonder how the OEMs did this as they used a lot of filler to blend into the tail cone and to fill in the belt sander marks from the removal of the mold part lines.
I put down a coat of Shop Line PPG primer and let it stabilize for close to a year.
(That's my story and I'm sticking to it!) I block sanded this coat to the state you see now. The primer has stood the test of time and my sanding block. I still have a few low spots to build back up with primer.I'm wondering with the OEM filler issue how much validity to give the flame polish process.
As this PPG Shop Line primer is a catalyzed product I'll wait until I have some of my other F3F ships ready for primer before mixing up a batch.
Last edited:
Glenn Beer
Active User
The method I used to fit wing to fuse was to apply a light weight epoxy putty to edges of wing root. Wrap fuse in Saran Wrap, attach wings to fuse and press to extrude most of putty. Wait for putty to kick. Trim flush to faces of airfoil.
Konrad
Very Strong User
The serpentine wing root does fit the fuselage rather well. It is just that the alignment pin places the wing at a higher angle of incidence. So much so that the trailing edge of the wing is hanging below the fuselage. The curve of the wing root does not match the curve of the fuselage at that angle setting.
Moving the front alignment pin up in the wing will allow the wing trailing edge to come up against the fuselage. A big benefit is that this will allow me to lower the decalage from 2° to 1° maybe even 0.5°. (Recall that with the kinked tail housing I've lowered the decalage from about 6° to about 2°. For a modern set up I'd like to see a decalage of 1.5° maybe even down as far as 0.5°)
I'm hoping this keeps the classic Hobie Hawk root junction, high tail stance. All at the same time allowing me to set the CG aft enough to minimize the trim changes as the speed changes.
Moving the front alignment pin up in the wing will allow the wing trailing edge to come up against the fuselage. A big benefit is that this will allow me to lower the decalage from 2° to 1° maybe even 0.5°. (Recall that with the kinked tail housing I've lowered the decalage from about 6° to about 2°. For a modern set up I'd like to see a decalage of 1.5° maybe even down as far as 0.5°)
I'm hoping this keeps the classic Hobie Hawk root junction, high tail stance. All at the same time allowing me to set the CG aft enough to minimize the trim changes as the speed changes.
Konrad
Very Strong User
Working on more cannon fodder for Sunset.
WOW, What slowed me down on this was having to move the alignment pins to fit the wings to the fuselage. Some of you might recall that some Hobie Hawks had the TE of the wing draging down below the fuselage. This was just gross and very draggy!
Here I've moved the alignment tubes in the wing about 0.7mm up the wing root. This is looking great. The trick was how to remove the factory installed tubes. I find that this is best done with a hole saw. What was nice is the the kerf of the hole saw allows the alignment tube to move up. As I'm sure there is some damage to the blue foame core of the wings I glued the alignment tubes in with expanding polyurethane glue.
As we all know the Hobie Hawk is rigged with gross decalage. This can only help to cut this down. It's only about a degree but anything helps!
WOW, What slowed me down on this was having to move the alignment pins to fit the wings to the fuselage. Some of you might recall that some Hobie Hawks had the TE of the wing draging down below the fuselage. This was just gross and very draggy!
Here I've moved the alignment tubes in the wing about 0.7mm up the wing root. This is looking great. The trick was how to remove the factory installed tubes. I find that this is best done with a hole saw. What was nice is the the kerf of the hole saw allows the alignment tube to move up. As I'm sure there is some damage to the blue foame core of the wings I glued the alignment tubes in with expanding polyurethane glue.
As we all know the Hobie Hawk is rigged with gross decalage. This can only help to cut this down. It's only about a degree but anything helps!
Konrad
Very Strong User
WOW, again I'm destroying the mystique that is the Hobie Hawk! Ether they really where poor models or mine was built (sold) from parts that failed QA testing. As you will recall my wing had voids in the TE foam. The skins where bonded on top of the root rib recess (not in the recess)!
Here I show that the through holes for the wing joiner and alignment rods are grossly out of parallel! No wonder the right wing was showing all the crash damage! it looks like the right wing was held at a lot higher angle of incidence than the left. this resulted in any stall falling sharply to the right!
Here I show that the through holes for the wing joiner and alignment rods are grossly out of parallel! No wonder the right wing was showing all the crash damage! it looks like the right wing was held at a lot higher angle of incidence than the left. this resulted in any stall falling sharply to the right!
Konrad
Very Strong User
Paint is a process!!!
With this plastic, one is trying to maintain a positive charge while painting. But as to the paint I'm using catalyzed PPG Delfleet Essential custom mixed red.
Last edited:
I think we will announce a vintage flying time frame each day.. ?
I don't recall, did you figure out what company built yours? I have heard some say the ones built by Midwest were pretty bad. The one we gave away at Sunset a couple of years ago was an original Hobie. Not sure who made more of them, Bob Martin, Midwest or Hobie?
I don't recall, did you figure out what company built yours? I have heard some say the ones built by Midwest were pretty bad. The one we gave away at Sunset a couple of years ago was an original Hobie. Not sure who made more of them, Bob Martin, Midwest or Hobie?
Konrad
Very Strong User
Then there is the OEM Ross. No, I don't KNOW for sure who the OEM of mine is. I think it is a late Hobie.
But ether way if it isn't clear, I don't like the engineering that is the Hobie Hawk. It was interesting in the 70's but let's be frank, they should have stayed in the 70's along with the bell bottom jeans! Who came up with the idea that these jeans are feeling a bit tight, so we need more room in the ankles!
Marketing and fashion, things I can't comprehend!
But ether way if it isn't clear, I don't like the engineering that is the Hobie Hawk. It was interesting in the 70's but let's be frank, they should have stayed in the 70's along with the bell bottom jeans! Who came up with the idea that these jeans are feeling a bit tight, so we need more room in the ankles!
Marketing and fashion, things I can't comprehend!
Konrad
Very Strong User
That just might draw me in/out. Any definition of Vintage?
Last edited:
I have to disagree with you about the engineering that is the Hobie Hawk. For their day they introduced a number of new technologies to the hobby. I may be wrong here, but if some of these existed prior, they were probably very limited in use:
Hobie spent a lot of time and money to develop this model. No one doubts that, and the model is still a rather high performance sport plane. You may not like some of the choices they landed on, but the plane was far beyond anything else on the market at the time. I dare say I do not know of a hotter rudder elevator plane today!
Yes, I admire the Hawk. And let's face it she is a beauty in the air. I imagine more then a few choices were picked simply for better presentation. The plane could have had simple dihedral, but that would have been boring.
Hobie has a track record for changing the sports he was involved with. Surfing, sailing and then the Hobie Hawk. All of his products pushed the owners to a much higher skill level. He took big heavy and lazy surfboards and made them into light weight high reaction boards. You don't just sail a Hobie 16, you wear that boat and it will make you work! Same for the Hobie Hawk.
- 1/64" plywood sheeted foam core wings (1/64" on one side, 1/32" on the other)
- Almost Ready To Fly and I also think you could buy them complete with radio.
- While I imagine some others were using fiberglass, I doubt others were using rotomolding, vacuum forming and casting acrylic (or was it ABS?) and bonding the three together. That lone is a lot of engineering.
- And let's not forget about the rocking chair dihedral. Like it or hate it, it did its job despite complexity.
- Full flying elevator and rudder was probably rather unique at the time.
Hobie spent a lot of time and money to develop this model. No one doubts that, and the model is still a rather high performance sport plane. You may not like some of the choices they landed on, but the plane was far beyond anything else on the market at the time. I dare say I do not know of a hotter rudder elevator plane today!
Yes, I admire the Hawk. And let's face it she is a beauty in the air. I imagine more then a few choices were picked simply for better presentation. The plane could have had simple dihedral, but that would have been boring.
Hobie has a track record for changing the sports he was involved with. Surfing, sailing and then the Hobie Hawk. All of his products pushed the owners to a much higher skill level. He took big heavy and lazy surfboards and made them into light weight high reaction boards. You don't just sail a Hobie 16, you wear that boat and it will make you work! Same for the Hobie Hawk.
Konrad
Very Strong User
I'm no hobby historian. Now let's remember that the Hobie Hawk was a mid 70's creation (1974?). Back then we had foam wing cores . Most European manufactures (Graupner, Simpro, Robbe, etc) where using a hardwood (Obeche)for lamination of the skins. I think Hal DeBolt or Ed Kazmirski is credited with the foam wing core for our RC planes in the late 50's or early 60's. So nothing really new in the wing materials.
The use of Fiberglass fuselage was well established even by the early 70's. I recall a firm Glass-crafter (?) making heavy junk with polyester resins.
Vacuum molded ABS was again standard in kits at the time. Injection molded parts where standard such as spinners, wheel hubs, bell cranks, radio parts, etc. Now the Rotomolding, I'll give it to Hobie for our models. Now part of engineering is cost per unit. I think here, the Hobie Hawk was a failure with the high cost of the fuselage and the delicate nature of the ass end. Poor engineering when looked at from a material and cost to manufacture perspective.
Hobie used a press to form the wings. I do like that idea. But there isn't anything new in the final shape. In1972 1970 Mark Smith's Windfree had you soak the upper wing structure when dried we got a nice upturned curved dihedral. So again nothing really new in the Hobie Hawk wing.
Staying with the wing In the late 60's Graupner taught us with the Cirrus that we don't want the banana style airfoil, that the flat bottom was far superior when hunting and coring thermals. (BTW: I see alot of injected ABS front fuse. parts in that 60's kit). What we have with the Hobie Hawk, is a model that is set up like the Zaic free flight Thermic series sailplane with a free flight airfoil and decalage. Basically a gross RC ship for the time frame of the mid 70's.
As an ARF the Hobie Hawk was a neat looking but poor performing model that was way too expensive as a result of poor engineering choices. If looked at against the Hobby Shack Sprit of 76 it was fantastic, that is a low bar. Assuming cost was no object and that you felt comfortable comparing a 72" glider against a 99" glider. As a RTR Hobie was a bit ahead of his time, in that a 2 channel radio was too expensive and limiting for the market segment. Again a market failure.
By the late 70's I was actually flying against the Hobie Hawks on the flat fields and on Green Mountain just west of Denver. I can unequivocally say that my 1972 design Windfree would out fly the Hobby Hawk every time we flew together! This was with a model that was 1/10 the cost. The Windfree had full flying stabs and rudder. Now were these a good idea? That is for another discussion!
Hobie (Hobart Alter) like Steve Jobs was a great marketer and changed may fields. But to the RC world he was but a short flash that really didn't change the landscape much. His influence did last for a while with the durathane fuselage we saw with the Bob Martin gliders.
What I think we see is Hobie's great marketing in the press. I still recall lusting after a Hobie Hawk after seeing the RCM ads. But having see them and flown against them and now trying to set one up they don't live up to the hype. I'm all but positive that flying one will not change my opinion of the them, be it their engineering and or flight performance. Like I said The Hobie Hawk and the idea of the Hobie Hawk should best be left in the 70's.
The use of Fiberglass fuselage was well established even by the early 70's. I recall a firm Glass-crafter (?) making heavy junk with polyester resins.
Vacuum molded ABS was again standard in kits at the time. Injection molded parts where standard such as spinners, wheel hubs, bell cranks, radio parts, etc. Now the Rotomolding, I'll give it to Hobie for our models. Now part of engineering is cost per unit. I think here, the Hobie Hawk was a failure with the high cost of the fuselage and the delicate nature of the ass end. Poor engineering when looked at from a material and cost to manufacture perspective.
Hobie used a press to form the wings. I do like that idea. But there isn't anything new in the final shape. In
Staying with the wing In the late 60's Graupner taught us with the Cirrus that we don't want the banana style airfoil, that the flat bottom was far superior when hunting and coring thermals. (BTW: I see alot of injected ABS front fuse. parts in that 60's kit). What we have with the Hobie Hawk, is a model that is set up like the Zaic free flight Thermic series sailplane with a free flight airfoil and decalage. Basically a gross RC ship for the time frame of the mid 70's.
As an ARF the Hobie Hawk was a neat looking but poor performing model that was way too expensive as a result of poor engineering choices. If looked at against the Hobby Shack Sprit of 76 it was fantastic, that is a low bar. Assuming cost was no object and that you felt comfortable comparing a 72" glider against a 99" glider. As a RTR Hobie was a bit ahead of his time, in that a 2 channel radio was too expensive and limiting for the market segment. Again a market failure.
By the late 70's I was actually flying against the Hobie Hawks on the flat fields and on Green Mountain just west of Denver. I can unequivocally say that my 1972 design Windfree would out fly the Hobby Hawk every time we flew together! This was with a model that was 1/10 the cost. The Windfree had full flying stabs and rudder. Now were these a good idea? That is for another discussion!
Hobie (Hobart Alter) like Steve Jobs was a great marketer and changed may fields. But to the RC world he was but a short flash that really didn't change the landscape much. His influence did last for a while with the durathane fuselage we saw with the Bob Martin gliders.
What I think we see is Hobie's great marketing in the press. I still recall lusting after a Hobie Hawk after seeing the RCM ads. But having see them and flown against them and now trying to set one up they don't live up to the hype. I'm all but positive that flying one will not change my opinion of the them, be it their engineering and or flight performance. Like I said The Hobie Hawk and the idea of the Hobie Hawk should best be left in the 70's.
Last edited:
Konrad
Very Strong User
I pickle forked one. Maybe that's why I don't like the Hawk. I'm subconsciously blaming Hobie for the rigging burns on my chest and thighs!
In good hands (not mine) the Hawk is still a good performer. Your Windfree probably did outclass the Hobie for thermal, it was probably half the weight too, but put your Windfree on the slopes of the Pacific and compare them. That is a different equation.
I have seen the Hawk thermal exactly once and I was impressed with how well it did off a high start in a flat field. I have always considered them a slope machine.
Surprised you have not flown one. For the average pilot the handling is horrible. There are 2 types of pilots, those that can fly a Hobie and those that can not (or have not). At this point with my 30 minutes of Hobie time I'll fully admit I suck at flying one of these smoothly.
Winfield on Youtube is known for flying rudder elevator ships in a super smooth fashion and what seems like a magical slope for his planes. Go watch his Hobie Hawk video.. You will see he was struggling with the handling of the plane.
If you can fly a Hobie well, then you can fly anything with a rudder better than most. It forces good stick technique into the pilot.
I have seen the Hawk thermal exactly once and I was impressed with how well it did off a high start in a flat field. I have always considered them a slope machine.
Surprised you have not flown one. For the average pilot the handling is horrible. There are 2 types of pilots, those that can fly a Hobie and those that can not (or have not). At this point with my 30 minutes of Hobie time I'll fully admit I suck at flying one of these smoothly.
Winfield on Youtube is known for flying rudder elevator ships in a super smooth fashion and what seems like a magical slope for his planes. Go watch his Hobie Hawk video.. You will see he was struggling with the handling of the plane.
If you can fly a Hobie well, then you can fly anything with a rudder better than most. It forces good stick technique into the pilot.
