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Aerobatic weight
- Thread starter F1 Rocket
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swaneymj
Active Member
From the assembly manual:
2.2.2 Aerobatic Maneuvers
Aerobatic maneuvers are permitted within the following limitations:
Aircraft weight not to exceed 2000 lbs, G limits are +6/-3
Aft C of G limit not to exceed 97.4? aft of datum (where datum is 80? fwd of wing leading edge)
2.2.2 Aerobatic Maneuvers
Aerobatic maneuvers are permitted within the following limitations:
Aircraft weight not to exceed 2000 lbs, G limits are +6/-3
Aft C of G limit not to exceed 97.4? aft of datum (where datum is 80? fwd of wing leading edge)
I?ve been told those limits are not correct and are in fact much less. I?ve been told that since the sport wing is based on a RV4 the limits should be based on that wing, adjusted for the reduced span. I believe the RV4 is limited to 1375 lbs. it?s the ?adjusted for the reduced span? number I?m looking for. I was told I would need to do the calculation myself but I?m not a structural engineer. I?m hoping someone has done this calculation and is willing to share this info. The person who I spoke to has the info but does not want to be sued by publishing it. I understand his position. I just want to operate my aircraft safely.
Keep in mind the RV4 G limits may have been based on factors beyond just the wing. I know that with the original Harmon Rocket a full engineering analysis was done. The wing is not just shortened, it retains the same number of internal ribs as the longer wing with a different center section and on the F1 I believe the skins are different. When the F1 kit was put together I am told another analysis was done by Czech engineers. Hopefully those involved will chime in. I am not aware of any wing strength issues or failures on a F1 or Harmon Rocket. The tail has been a different story but issues have been minimal on the Harmon and the two F1 I know that had a flutter issue were well beyond design speeds.
G
G
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swaneymj
Active Member
Here are a few comments on aerobatics copied from the old F1 Forum archives just for reference and safety:
1. Also note if you?re going to be doing aero work on a regular basis it would be prudent to make inspection of the outer .040 skin adjacent to outer #8 attach screws of the firewall attach brackets part of you?re preflight. The reason would be the skin picks up some load in that area, understandable since Rockets have monsters engines in them as compared to the RV?s.
2. Vne is a TAS in thse planes ? do a bit of math and re-figure this number if you are doing high-altitude maneuvers. Do not exceed Vne ? if you do, reduce power and G up the plane ? (2-3Gs should be OK). In allowing a rear seat PAX to do some maneuvering, I found myself in a split-S entry at 180KIAS @ about 5000?MSL. I said ?I?VE GOT IT" as soon as I figured out this was not a hesitation roll (we were vertical at this point), and I simply reduced power. The plane slowed to 200MPH indicated, and appeared to want to continue to slow, but it was time to pull to level.
3. in reality, you have 2 different planes: one that flies nicely when solo, and another that flies with very light pitch forces when flown dual. When you do acro 2-up, be sure to use the stick as a control device, not a wing-removal lever.
4. IMHO, Flying a Rocket is very different to flying a typical acro aircraft.
Most traditional acro aircraft have high drag and low power to weight compared to a Rocket.
What this means is that everytime you point it at the ground it is going to accelerate faster than you might expect.
When starting out, go to idle on all down lines. Even on basic stuff like loops, go to idle once you pass the inverted. Once you know the aircraft characteristics, you can fly high speed acro with higher exit powers but I would not start there.
Mark is very correct, of course, speeds aren?t that important. Fly a loop from 110 kts or 240 kts both are possible. In general start slow, you are less likely to get in trouble on the exits, so for the loop, start at 140 to 150, 3g and idle on the down hill. Get the idea?
Small steps is my advice and be careful taking advice from people who have only flown acro in stuff like Decathlons and even older Pitts ? they don?t bite with over speeds like your Rocket can!
5. When doing a hammerhead in a rocket make very sure that the plane has quit flying. If the wing is developing any lift you will be in an inverted spin in the blink of an eye. This isn?t a problem, just use normal spin recovery techniques. It happens fast enough it will take you by surprise the first time. The same recovery for a normal spin. (see #6.) Stand on the rudder to stop the rotation and ease out of the dive. Rockets spin real fast. If you can spin one and come out on a chosin heading you?re doing real well. If you like to wind things up the rocket will turn you on, but make sure you have a lot of space between you and mother earth.
6. I noticed that in a previous post someone wrote that recovery from in an inverted spin is "the same" as an upright spin. This is not true. For an upright spin, opposite rudder and forward stick is used to break the yaw/stall. If forward stick is used in an inverted spin, you very well could remain stalled and not recover. AFT stick must be used to break the stall when in an inverted stall. Rudder alone may not be effective enough to stop the yaw.
Inverted spins are very disorienting. It is very hard to keep "it" together when suddenly and unexpectedly you find yourself hanging upside down and flailing around. Plumeting to the ground, it would seem counter-intuitive to pull back on the stick to break the stall, but that is what is needed. Being proficient in normal spins does not mean you are competent to recover from an inverted spin.
ALL airplanes spin differently, and spin characteristics in a particular airplane are very dependent on CG, fuel on board (moment of inertia), power setting, control position, etc. Aft CG (rear passenger) can make spin recovery more difficult for a number of reasons, upright or inverted. A recovery technique that works in one airplane may well not work in any or all.
How do you get in an inverted spin? The easiest way I have seen is in the recovery from an upright spin. If forward stick is held too long, the transition from an upright spin to an inverted spin is alarmingly fast and easy. Can?t tell you how many of these I saw teaching? What?s another way to get in an inverted spin? Hammerheads, immel"spins", or simply inverted stalls.
I have spun my F1 "sport" wing several times, (up to two turns and at varying fuel weights) and have found recovery to be very straight forward with conventional recovery inputs. Spin entry and rate are relatively timid. I have NOT spun it with a back seater, nor have I attempted inverted spins. I have not heard of anyone who has, but would be interested to hear details. I would expect recovery from an inverted spin to be very positive with full aft stick.
Hope this generates some discussion, or increases the level of awareness of spins. The F1 is a fantastic aerobatic airplane, but is very different from a decathlon or a pitts.
BOTTOM LINE: Don?t attempt aerobatics without competent instruction. Even a simple "aileron roll" can put you at risk.Aerobatics courses generally start with unusual attitude recognition and recovery and spin recoveries. Go do it with a pro first?this is one area not to be "experimental".
1. Also note if you?re going to be doing aero work on a regular basis it would be prudent to make inspection of the outer .040 skin adjacent to outer #8 attach screws of the firewall attach brackets part of you?re preflight. The reason would be the skin picks up some load in that area, understandable since Rockets have monsters engines in them as compared to the RV?s.
2. Vne is a TAS in thse planes ? do a bit of math and re-figure this number if you are doing high-altitude maneuvers. Do not exceed Vne ? if you do, reduce power and G up the plane ? (2-3Gs should be OK). In allowing a rear seat PAX to do some maneuvering, I found myself in a split-S entry at 180KIAS @ about 5000?MSL. I said ?I?VE GOT IT" as soon as I figured out this was not a hesitation roll (we were vertical at this point), and I simply reduced power. The plane slowed to 200MPH indicated, and appeared to want to continue to slow, but it was time to pull to level.
3. in reality, you have 2 different planes: one that flies nicely when solo, and another that flies with very light pitch forces when flown dual. When you do acro 2-up, be sure to use the stick as a control device, not a wing-removal lever.
4. IMHO, Flying a Rocket is very different to flying a typical acro aircraft.
Most traditional acro aircraft have high drag and low power to weight compared to a Rocket.
What this means is that everytime you point it at the ground it is going to accelerate faster than you might expect.
When starting out, go to idle on all down lines. Even on basic stuff like loops, go to idle once you pass the inverted. Once you know the aircraft characteristics, you can fly high speed acro with higher exit powers but I would not start there.
Mark is very correct, of course, speeds aren?t that important. Fly a loop from 110 kts or 240 kts both are possible. In general start slow, you are less likely to get in trouble on the exits, so for the loop, start at 140 to 150, 3g and idle on the down hill. Get the idea?
Small steps is my advice and be careful taking advice from people who have only flown acro in stuff like Decathlons and even older Pitts ? they don?t bite with over speeds like your Rocket can!
5. When doing a hammerhead in a rocket make very sure that the plane has quit flying. If the wing is developing any lift you will be in an inverted spin in the blink of an eye. This isn?t a problem, just use normal spin recovery techniques. It happens fast enough it will take you by surprise the first time. The same recovery for a normal spin. (see #6.) Stand on the rudder to stop the rotation and ease out of the dive. Rockets spin real fast. If you can spin one and come out on a chosin heading you?re doing real well. If you like to wind things up the rocket will turn you on, but make sure you have a lot of space between you and mother earth.
6. I noticed that in a previous post someone wrote that recovery from in an inverted spin is "the same" as an upright spin. This is not true. For an upright spin, opposite rudder and forward stick is used to break the yaw/stall. If forward stick is used in an inverted spin, you very well could remain stalled and not recover. AFT stick must be used to break the stall when in an inverted stall. Rudder alone may not be effective enough to stop the yaw.
Inverted spins are very disorienting. It is very hard to keep "it" together when suddenly and unexpectedly you find yourself hanging upside down and flailing around. Plumeting to the ground, it would seem counter-intuitive to pull back on the stick to break the stall, but that is what is needed. Being proficient in normal spins does not mean you are competent to recover from an inverted spin.
ALL airplanes spin differently, and spin characteristics in a particular airplane are very dependent on CG, fuel on board (moment of inertia), power setting, control position, etc. Aft CG (rear passenger) can make spin recovery more difficult for a number of reasons, upright or inverted. A recovery technique that works in one airplane may well not work in any or all.
How do you get in an inverted spin? The easiest way I have seen is in the recovery from an upright spin. If forward stick is held too long, the transition from an upright spin to an inverted spin is alarmingly fast and easy. Can?t tell you how many of these I saw teaching? What?s another way to get in an inverted spin? Hammerheads, immel"spins", or simply inverted stalls.
I have spun my F1 "sport" wing several times, (up to two turns and at varying fuel weights) and have found recovery to be very straight forward with conventional recovery inputs. Spin entry and rate are relatively timid. I have NOT spun it with a back seater, nor have I attempted inverted spins. I have not heard of anyone who has, but would be interested to hear details. I would expect recovery from an inverted spin to be very positive with full aft stick.
Hope this generates some discussion, or increases the level of awareness of spins. The F1 is a fantastic aerobatic airplane, but is very different from a decathlon or a pitts.
BOTTOM LINE: Don?t attempt aerobatics without competent instruction. Even a simple "aileron roll" can put you at risk.Aerobatics courses generally start with unusual attitude recognition and recovery and spin recoveries. Go do it with a pro first?this is one area not to be "experimental".
vfrazier
Well Known Member
The text in bold is a typo or other editing error that crept into the manual previously. There is NO way that those 2 statements are correct when stated together. The aircraft gross weight is 2000 lbs, but at that weight the +6/-3 is NOT correct. Please keep reading.
The Harmon and Team Rocket wings are based upon the RV-4 wing, which has a 23' wing span. The Rocket wing is shorter, with a total span of 21' 10" or about 14" less than the RV-4. However, the Rocket's slightly wider fuselage means that the wing panels are even shorter on the Rocket, by almost a foot per wing (when you exclude the center section).
The same number of ribs are used, with slightly tighter spacing. The tighter rib spacing reduces skin oil canning a small amount, but does not appreciably increase the strength of the wing.
However, the shorter wing results in a stiffer wing in bending. In addition, the shorter wing also uses .032" skins along the entire span, if the builder used the optional one piece skins, as most did. The .032" skins helps marginally in bending, but also results in a torsionally stiffer wing.
Team Rocket supports John Harmon's statement, as mentioned by Danny Melnik in the post above, that aerobatic weight should not exceed 1550 Lbs. At this weight, we recommend +5/-3 G. The lower weight is not only for wing spar considerations, but is also to minimize inertial loads on the tail and fuselage, and to have a more consistent pitch response.
Furthermore, the laws of physics are true and inflexible. Doing acro with a passenger moves the CG aft. An aft CG has a large effect on stick forces in a bad way. It is all too easy to pull far more G than expected with an aft CG. In other words, stick force per G is very low. A very light pull can result in a large G load. Aft CG is detrimental to spin recovery also.
So, unless you and your passenger are horse race jockeys, there is no acceptable way to do dual acro in a Rocket. And don't forget that parachutes are also required, and so is fuel. Dual acro simply isn't feasible or recommended.
Team Rocket recommends solo aerobatics only, and only after proper training has been received. What Mark Swaney said above about aerobatics is spot on. However, the manual entry claiming a 2000 lb gross weight and +6/-3 Gs is incorrect and should be removed from any POH, builder's manual, or any other document, that you may have.
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swaneymj
Active Member
Maybe we can get F1 Boss to chime in. The oldest copy of the F1 Sample Flight Manual I have is REV 2.17, 4 Jan 2002, but it has the quoted limits. Agree it doesn't make sense. For normal operations the manual says the CG range is 87.7" to 97.4" at all weights. So physics says it should be less than the Manual has in the aerobatics section that was quoted:
"Aerobatic maneuvers are permitted within the following limitations:
Aircraft weight not to exceed 2000 lbs, G limits are +6/-3
Aft C of G limit not to exceed 97.4? aft of datum (where datum is 80? fwd of wing leading edge)". Using John's numbers, 1550# and +5/-3 G, limits you to about 30 gal of fuel with a 200# pilot (assuming 1200# empty). My F1 is heavier than that (and so am I unfortunately) so other than solo aerobatics looks like a BIG risk!!
"Aerobatic maneuvers are permitted within the following limitations:
Aircraft weight not to exceed 2000 lbs, G limits are +6/-3
Aft C of G limit not to exceed 97.4? aft of datum (where datum is 80? fwd of wing leading edge)". Using John's numbers, 1550# and +5/-3 G, limits you to about 30 gal of fuel with a 200# pilot (assuming 1200# empty). My F1 is heavier than that (and so am I unfortunately) so other than solo aerobatics looks like a BIG risk!!
