BVM T-33 Build
05-15-2013, 08:41 AM
#76
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RE: BVM T-33 Build
ORIGINAL: sideshow
Has anyone bought the composite wings? I'm looking at either getting the new wings or modifying what I have. The last time I called BVM they didn't have a price. Any info on price or how they fit would be appreciated.
Has anyone bought the composite wings? I'm looking at either getting the new wings or modifying what I have. The last time I called BVM they didn't have a price. Any info on price or how they fit would be appreciated.
Since my post above, my T-33 experienced some non-destructive outer wing LCO flutter at approx 120 mph. The wings are old vintage with balsa skins. It caught me off guard as it was a medium speed pass, but the flutter commenced after I initiated a slight bank...meaning the aileron stimulated the wing flutter at that speed. I immediately landed without incident and there was no apparent damage to the wing, and the wing stiffness felt to be unreduced. However, the classic T-33 wing is not very stiff in torsion, say compared to a Composite Bandit wing, and has tip tanks at the tips to keep aligned against the aero forces. I have since improved the torsional stiffness of the wings with adding 2oz fiberglass cloth over the outer skins with the grain of cloth on 45 deg to the span. After finishing, this added approx 3 oz in weight to each wing, but has significantly increased the stiffness. Also, the wing tubes were a little sloppy in their housings, which could have also contributed to the problem. After speaking with Bob V, he wanted me to buy new wings and to paint the wing tubes with primer to slightly increase the diameter to remove the slop.
All this work is done (added 2 oz cloth and eliminated slop with the tubes), but I haven't flight tested it yet. I will let you know how it works out.
Cheers,
05-15-2013, 03:03 PM
#77
RE: BVM T-33 Build
OROGINAL: JDjetjock
I will let you know how it works out.
I will let you know how it works out.
ORIGINAL: JackD
I havent started the build (finishing other project right now) but I soon as I start, we should compare notes
Later
jack
I havent started the build (finishing other project right now) but I soon as I start, we should compare notes
Later
jack
05-15-2013, 04:33 PM
#78
RE: BVM T-33 Build
ORIGINAL: sideshow
Sounds great Jack. My kit has the old plastic retracts which I'm going to replace with the new purple ones. I was going to put a solid carbon spar attached to the wing tube in. Looking forward to hearing about your method.
Sounds great Jack. My kit has the old plastic retracts which I'm going to replace with the new purple ones. I was going to put a solid carbon spar attached to the wing tube in. Looking forward to hearing about your method.
Tell me about the carbon spar. Where are you putting it? One of the issues to solve is that the tube can come loose inside the wing. SO that is why I want to "sandwich" the tube with the 2 balsa/carbon stringers on top and bottom. that will create a more solid continuity between the wingtube and the wing.
And i meant using 2oz cloth, not 1.5Oz (i dont even think that exists...)
05-15-2013, 06:29 PM
#81
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RE: BVM T-33 Build
You may want to double check the main wing spar center section. The wing flutter could have started there. Remember, that vintage of kit was designed well before the first turbine jet flew. The main wing spar if I remember has an open hoop design that went around the ducted fan but was left open on the upper half. Like on the F-16 BVM put a hoop section on the top of the spar to complete the hoop so to speak. Picture a horse shoe upside down, there would be a carbon former made to connect the two open ends of the shoe. This will greatly reduce the amount of wing flex.
05-15-2013, 06:47 PM
#82
RE: BVM T-33 Build
ORIGINAL: JackD
Tell me about the carbon spar. Where are you putting it? One of the issues to solve is that the tube can come loose inside the wing. SO that is why I want to ''sandwich'' the tube with the 2 balsa/carbon stringers on top and bottom. that will create a more solid continuity between the wingtube and the wing.
And i meant using 2oz cloth, not 1.5Oz (i dont even think that exists...)
Tell me about the carbon spar. Where are you putting it? One of the issues to solve is that the tube can come loose inside the wing. SO that is why I want to ''sandwich'' the tube with the 2 balsa/carbon stringers on top and bottom. that will create a more solid continuity between the wingtube and the wing.
And i meant using 2oz cloth, not 1.5Oz (i dont even think that exists...)
05-16-2013, 03:39 PM
#83
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RE: BVM T-33 Build
ORIGINAL: Kelly Rohrbach
You may want to double check the main wing spar center section. The wing flutter could have started there. Remember, that vintage of kit was designed well before the first turbine jet flew. The main wing spar if I remember has an open hoop design that went around the ducted fan but was left open on the upper half. Like on the F-16 BVM put a hoop section on the top of the spar to complete the hoop so to speak. Picture a horse shoe upside down, there would be a carbon former made to connect the two open ends of the shoe. This will greatly reduce the amount of wing flex.
You may want to double check the main wing spar center section. The wing flutter could have started there. Remember, that vintage of kit was designed well before the first turbine jet flew. The main wing spar if I remember has an open hoop design that went around the ducted fan but was left open on the upper half. Like on the F-16 BVM put a hoop section on the top of the spar to complete the hoop so to speak. Picture a horse shoe upside down, there would be a carbon former made to connect the two open ends of the shoe. This will greatly reduce the amount of wing flex.
Hi Kelly,
Good idea...I'll double check the centre section. I do know that it was originally a BVM configured one for a JPX turbine and has the carry through structure in the upper fuse, but will check it anyway. Thanks.
05-17-2013, 03:27 PM
#84
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RE: BVM T-33 Build
ORIGINAL: Kelly Rohrbach
You may want to double check the main wing spar center section. The wing flutter could have started there. Remember, that vintage of kit was designed well before the first turbine jet flew. The main wing spar if I remember has an open hoop design that went around the ducted fan but was left open on the upper half. Like on the F-16 BVM put a hoop section on the top of the spar to complete the hoop so to speak. Picture a horse shoe upside down, there would be a carbon former made to connect the two open ends of the shoe. This will greatly reduce the amount of wing flex.
You may want to double check the main wing spar center section. The wing flutter could have started there. Remember, that vintage of kit was designed well before the first turbine jet flew. The main wing spar if I remember has an open hoop design that went around the ducted fan but was left open on the upper half. Like on the F-16 BVM put a hoop section on the top of the spar to complete the hoop so to speak. Picture a horse shoe upside down, there would be a carbon former made to connect the two open ends of the shoe. This will greatly reduce the amount of wing flex.
BR
Jesus A. Serrano
05-17-2013, 10:58 PM
#86
RE: BVM T-33 Build
ORIGINAL: AVIOJET
You are refering to this one? I built this T-33 for a customer more than 10 years ago. He flew it with a P-60 and no issues with flutter.
BR
Jesus A. Serrano
ORIGINAL: Kelly Rohrbach
You may want to double check the main wing spar center section. The wing flutter could have started there. Remember, that vintage of kit was designed well before the first turbine jet flew. The main wing spar if I remember has an open hoop design that went around the ducted fan but was left open on the upper half. Like on the F-16 BVM put a hoop section on the top of the spar to complete the hoop so to speak. Picture a horse shoe upside down, there would be a carbon former made to connect the two open ends of the shoe. This will greatly reduce the amount of wing flex.
You may want to double check the main wing spar center section. The wing flutter could have started there. Remember, that vintage of kit was designed well before the first turbine jet flew. The main wing spar if I remember has an open hoop design that went around the ducted fan but was left open on the upper half. Like on the F-16 BVM put a hoop section on the top of the spar to complete the hoop so to speak. Picture a horse shoe upside down, there would be a carbon former made to connect the two open ends of the shoe. This will greatly reduce the amount of wing flex.
BR
Jesus A. Serrano
05-19-2013, 03:12 PM
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RE: BVM T-33 Build
ORIGINAL: argyris
Mr Serrano how it flew with P-60?how much was the total weight dry and wet?Thank you!!
ORIGINAL: AVIOJET
You are refering to this one? I built this T-33 for a customer more than 10 years ago. He flew it with a P-60 and no issues with flutter.
BR
Jesus A. Serrano
ORIGINAL: Kelly Rohrbach
You may want to double check the main wing spar center section. The wing flutter could have started there. Remember, that vintage of kit was designed well before the first turbine jet flew. The main wing spar if I remember has an open hoop design that went around the ducted fan but was left open on the upper half. Like on the F-16 BVM put a hoop section on the top of the spar to complete the hoop so to speak. Picture a horse shoe upside down, there would be a carbon former made to connect the two open ends of the shoe. This will greatly reduce the amount of wing flex.
You may want to double check the main wing spar center section. The wing flutter could have started there. Remember, that vintage of kit was designed well before the first turbine jet flew. The main wing spar if I remember has an open hoop design that went around the ducted fan but was left open on the upper half. Like on the F-16 BVM put a hoop section on the top of the spar to complete the hoop so to speak. Picture a horse shoe upside down, there would be a carbon former made to connect the two open ends of the shoe. This will greatly reduce the amount of wing flex.
BR
Jesus A. Serrano
Till to day has loged more than 60 flights performing all kind of aerobatics and no issues. Tomorrow I will attach some pics
06-17-2013, 07:01 AM
#88
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RE: BVM T-33 Build
ORIGINAL: JDjetjock
Since my post above, my T-33 experienced some non-destructive outer wing LCO flutter at approx 120 mph. The wings are old vintage with balsa skins. It caught me off guard as it was a medium speed pass, but the flutter commenced after I initiated a slight bank...meaning the aileron stimulated the wing flutter at that speed. I immediately landed without incident and there was no apparent damage to the wing, and the wing stiffness felt to be unreduced. However, the classic T-33 wing is not very stiff in torsion, say compared to a Composite Bandit wing, and has tip tanks at the tips to keep aligned against the aero forces. I have since improved the torsional stiffness of the wings with adding 2oz fiberglass cloth over the outer skins with the grain of cloth on 45 deg to the span. After finishing, this added approx 3 oz in weight to each wing, but has significantly increased the stiffness. Also, the wing tubes were a little sloppy in their housings, which could have also contributed to the problem. After speaking with Bob V, he wanted me to buy new wings and to paint the wing tubes with primer to slightly increase the diameter to remove the slop.
All this work is done (added 2 oz cloth and eliminated slop with the tubes), but I haven't flight tested it yet. I will let you know how it works out.
Cheers,
ORIGINAL: sideshow
Has anyone bought the composite wings? I'm looking at either getting the new wings or modifying what I have. The last time I called BVM they didn't have a price. Any info on price or how they fit would be appreciated.
Has anyone bought the composite wings? I'm looking at either getting the new wings or modifying what I have. The last time I called BVM they didn't have a price. Any info on price or how they fit would be appreciated.
Since my post above, my T-33 experienced some non-destructive outer wing LCO flutter at approx 120 mph. The wings are old vintage with balsa skins. It caught me off guard as it was a medium speed pass, but the flutter commenced after I initiated a slight bank...meaning the aileron stimulated the wing flutter at that speed. I immediately landed without incident and there was no apparent damage to the wing, and the wing stiffness felt to be unreduced. However, the classic T-33 wing is not very stiff in torsion, say compared to a Composite Bandit wing, and has tip tanks at the tips to keep aligned against the aero forces. I have since improved the torsional stiffness of the wings with adding 2oz fiberglass cloth over the outer skins with the grain of cloth on 45 deg to the span. After finishing, this added approx 3 oz in weight to each wing, but has significantly increased the stiffness. Also, the wing tubes were a little sloppy in their housings, which could have also contributed to the problem. After speaking with Bob V, he wanted me to buy new wings and to paint the wing tubes with primer to slightly increase the diameter to remove the slop.
All this work is done (added 2 oz cloth and eliminated slop with the tubes), but I haven't flight tested it yet. I will let you know how it works out.
Cheers,
So, all is to say, that after adding 2oz glass cloth over the outer wing skins (on the 45), removing the wing tube slop, and reinforcing the tip tank fin assemblies, my 17 year old BVM T-33 flies great over a wide speed range.
All the best,
06-17-2013, 11:11 AM
#89
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RE: BVM T-33 Build
Here's the fix that BV gave me for my very old ex-ducted fan T-33.
The attached photo shows the position of the full depth 1/8" plywood spars.
The wing is much stiffer now, and the weight gain was minimal.
One Saturday I took my T-33 over to the shop, as BV had been asking about it. It was almost ready for paint, and any modification that I needed to make to the wings wouldn't be a problem.
He had suspected that the wings were probably too weak for a turbine conversion, and he was correct.
I added these spars in the locations BV determined. They are full depth, and rest on the upper wing skin inner surface, and the forward face of the aft spar socket.
The blue tape shows the position of the new spars, and the dimensions are shown. The wings have a base coat of white paint, in preparation for the yellow color to follow.
The forward spar should fit snugly between the root rib and the servo box liner.
The attached photo shows the position of the full depth 1/8" plywood spars.
The wing is much stiffer now, and the weight gain was minimal.
One Saturday I took my T-33 over to the shop, as BV had been asking about it. It was almost ready for paint, and any modification that I needed to make to the wings wouldn't be a problem.
He had suspected that the wings were probably too weak for a turbine conversion, and he was correct.
I added these spars in the locations BV determined. They are full depth, and rest on the upper wing skin inner surface, and the forward face of the aft spar socket.
The blue tape shows the position of the new spars, and the dimensions are shown. The wings have a base coat of white paint, in preparation for the yellow color to follow.
The forward spar should fit snugly between the root rib and the servo box liner.
10-25-2014, 09:22 AM
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I just bought a key-ready BVM T33 few days ago. The airplane looks very good, and it's very nicely built. Its powered by a jetcat p80se with kerostart. Im very exited
Its built from a old kit with glassed balsacovered wings. Seems like the wing is very strong, but i still have som conserns by reading about some issues on this thread. The airplane has flaps and airbrake and the wing has the scale underchamber. Do i need to fill this or does it preform well as it is? I know it flies well at high speeds, but i heard problems may occur at low speed and its easily bounce when it touch the ground. What do u guys think, do i need to modify?
Its built from a old kit with glassed balsacovered wings. Seems like the wing is very strong, but i still have som conserns by reading about some issues on this thread. The airplane has flaps and airbrake and the wing has the scale underchamber. Do i need to fill this or does it preform well as it is? I know it flies well at high speeds, but i heard problems may occur at low speed and its easily bounce when it touch the ground. What do u guys think, do i need to modify?Last edited by ole.foll; 10-25-2014 at 09:55 AM. Reason: f
10-25-2014, 09:58 AM
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10-25-2014, 05:24 PM
#94
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I just bought a key-ready BVM T33 few days ago. The airplane looks very good, and it's very nicely built. Its powered by a jetcat p80se with kerostart. Im very exited Its built from a old kit with glassed balsacovered wings. Seems like the wing is very strong, but i still have som conserns by reading about some issues on this thread. The airplane has flaps and airbrake and the wing has the scale underchamber. Do i need to fill this or does it preform well as it is? I know it flies well at high speeds, but i heard problems may occur at low speed and its easily bounce when it touch the ground. What do u guys think, do i need to modify?
Its built from a old kit with glassed balsacovered wings. Seems like the wing is very strong, but i still have som conserns by reading about some issues on this thread. The airplane has flaps and airbrake and the wing has the scale underchamber. Do i need to fill this or does it preform well as it is? I know it flies well at high speeds, but i heard problems may occur at low speed and its easily bounce when it touch the ground. What do u guys think, do i need to modify?- fill in the undercamber as described on the BVM website.
- incorporate crow on the ailerons (I deflect approx 1/4" to 3/8" up). The wing tends to tip stall, so adding crow is like adding washout to delay tip stalling.
- ensure no slop on the aluminum wing tubes (build up tubes with primer until nice fit). Otherwise you may have trim changes in flight.
- do not move CofG behind what is recommended. It tends to be very pitch sensitive on landing.
- replace the landing gear with the new mounts and purple gear (see BVM web site for mod kit). Any side loading on your old gear will break the mechanisms, and the turbine T-33 is much heavier than this version.
- do not fly with more than 30 deg crosswinds
- check if the oleos bottom out with a full fuel load. If so, BVM can provide additional springs to raise the jet up. Mine had this problem.
It's a beautiful flying aircraft.
Cheers,
10-26-2014, 04:36 AM
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I've owned and flown a couple older BVM T-33s and had much success. To ensure success, I recommend the following:
- fill in the undercamber as described on the BVM website.
- incorporate crow on the ailerons (I deflect approx 1/4" to 3/8" up). The wing tends to tip stall, so adding crow is like adding washout to delay tip stalling.
- ensure no slop on the aluminum wing tubes (build up tubes with primer until nice fit). Otherwise you may have trim changes in flight.
- do not move CofG behind what is recommended. It tends to be very pitch sensitive on landing.
- replace the landing gear with the new mounts and purple gear (see BVM web site for mod kit). Any side loading on your old gear will break the mechanisms, and the turbine T-33 is much heavier than this version.
- do not fly with more than 30 deg crosswinds
- check if the oleos bottom out with a full fuel load. If so, BVM can provide additional springs to raise the jet up. Mine had this problem.
It's a beautiful flying aircraft.
Cheers,
- fill in the undercamber as described on the BVM website.
- incorporate crow on the ailerons (I deflect approx 1/4" to 3/8" up). The wing tends to tip stall, so adding crow is like adding washout to delay tip stalling.
- ensure no slop on the aluminum wing tubes (build up tubes with primer until nice fit). Otherwise you may have trim changes in flight.
- do not move CofG behind what is recommended. It tends to be very pitch sensitive on landing.
- replace the landing gear with the new mounts and purple gear (see BVM web site for mod kit). Any side loading on your old gear will break the mechanisms, and the turbine T-33 is much heavier than this version.
- do not fly with more than 30 deg crosswinds
- check if the oleos bottom out with a full fuel load. If so, BVM can provide additional springs to raise the jet up. Mine had this problem.
It's a beautiful flying aircraft.
Cheers,
Is there anything else i should be aware of? What do u recommand for servo throw on the rudder, ailerons, elevator, airbrake? Do i need to add expo?
10-26-2014, 07:35 AM
#96
i just got one as well, did not get the tank winglets and thought leaving them off would be better. thanks for the advise on the crow programing JD since im going EVF it will be a lot lighter so I'll do Harley's mod but avoid the 2oz top and bottom and just do bottom after the spars are in
10-26-2014, 09:52 AM
#97
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Thank you for the good advises. The oleo legs bottom out very easily, so i have to add additional springs to raise it up as u says. I hope this undercarriage is strong enough. Its too expensive to buy the new purple one. My plan was to fly it with the orginal underchamber first for testing, but maybe its best to fill the underchamber in advanced. Adding washout to the ailerons sounds like a good idea. I will do that Is there anything else i should be aware of? What do u recommand for servo throw on the rudder, ailerons, elevator, airbrake? Do i need to add expo?
Is there anything else i should be aware of? What do u recommand for servo throw on the rudder, ailerons, elevator, airbrake? Do i need to add expo?BVM's CofG and control throws are in his website: http://www.bvmjets.com/Pages/CG.htm.
For expo, that's a pilot preference. For jets with a large speed range I use considerable expo (up to 60%) as I prefer not to be constantly changing rates by switches.
For the crow settings, I meant to also say that this is recommended when full flaps are deployed.
Cheers,
10-27-2014, 06:13 AM
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BVM's CofG and control throws are in his website: http://www.bvmjets.com/Pages/CG.htm.
For expo, that's a pilot preference. For jets with a large speed range I use considerable expo (up to 60%) as I prefer not to be constantly changing rates by switches.
For the crow settings, I meant to also say that this is recommended when full flaps are deployed.
Cheers,
For expo, that's a pilot preference. For jets with a large speed range I use considerable expo (up to 60%) as I prefer not to be constantly changing rates by switches.
For the crow settings, I meant to also say that this is recommended when full flaps are deployed.
Cheers,
Here is a few pictures of the retract mecanism in my tbird. Does'nt look very solid to me, so i dont know if this is strong enough?, Maybe its for the best to buy the new purple retracts from BVM even if i hope not to spend more money on this aircraft. What do u guys think? Is this the first generation bvm retracts? Last edited by ole.foll; 10-27-2014 at 07:05 AM.
10-27-2014, 08:05 AM
#99
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Those are first gen retracts. I would bite the bullet and get the newest versions and have peace of mind when I'm coming in for that first landing. Also do be sure to do the undercamber fill-in mod or you'll be sorry.
10-27-2014, 08:25 AM
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Yepp, thats what i thought. Im afraid its another 500$ for the retracts and the carbon mounts, but this model deserves it. It is in perfect condition and have never been flown yet. I hope i can use the legs and break system as it is. Im gonna make sure everything is perfect before the first flite. I will also fill the underchamber. What servos do u recommand ? Mine has jr8411 servoes on the elevator, ailrons, rudders and flaps. 13kgs tourqe at 6v. Hope this is enough. I consider to change the elevator and rudder to Hitec 7955 servos (tourqe 24kg) but i dont now if its necesarry.
Last edited by ole.foll; 10-27-2014 at 08:49 AM.
