CA2677126A1 - Bottom blade type vehicle - Google Patents

Bottom blade type vehicle Download PDF

Info

Publication number
CA2677126A1
CA2677126A1 CA2677126A CA2677126A CA2677126A1 CA 2677126 A1 CA2677126 A1 CA 2677126A1 CA 2677126 A CA2677126 A CA 2677126A CA 2677126 A CA2677126 A CA 2677126A CA 2677126 A1 CA2677126 A1 CA 2677126A1
Authority
CA
Canada
Prior art keywords
vehicle
leaf
adjusting
plates
blade type
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
CA2677126A
Other languages
French (fr)
Inventor
Key Dong Choi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to CA2677126A priority Critical patent/CA2677126A1/en
Publication of CA2677126A1 publication Critical patent/CA2677126A1/en
Abandoned legal-status Critical Current

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B64AIRCRAFT; AVIATION; COSMONAUTICS
    • B64UUNMANNED AERIAL VEHICLES [UAV]; EQUIPMENT THEREFOR
    • B64U30/00Means for producing lift; Empennages; Arrangements thereof
    • B64U30/20Rotors; Rotor supports

Abstract

A bottom blade type vehicle includes a fixed screw-pitch leaf horizontally mounted taking a center axis as the center; a power part mounted above the leaf; a controlling part mounted under the leaf; a first and a second fixing plates and a first and a second protecting plates being crossed each other in a cross-shape taking the controlling part as the center, one end of the first and the second fixing plates and the first and the second protecting plates connected to the controlling part and the other end of them connected to a round frame; a bridge plate vertically fixedly mounted under the round frame; and a first and a second adjusting controlled by a controlling device of the controlling part, wherein the first and the second adjusting blades are mounted on the first and the second protecting plates respectively.

Description

SPECIFICATIONS

BOTTOM BLADE TYPE VEHICLE
BACKGROUND OF THE INVENTION

5Technical Field The present invention relates to pilotless rotary-wing aircrafts, and more particularly, to a bottom blade type vehicle.

Description of Related Art Conventionally, a bottom blade type vehicle comprises a rotor and leaves l Opowered to rotate taking a center axis as the center, and also includes a power part, a controlling part, fixing plates, and adjusting blades. Among the known approaches to controlling the flight direction and achieving the flight stability of the existing bottom blade type vehicle, it is a popular one to implement a variable screw-pitch rotor that has plural leaves whose helix angles are to be repeatedly 15adjusted for controlling the flight direction of the vehicle. In another common approach, a transverse shaft are provided at the bottom of the vehicle for holding plural adjusting blades so that the flight direction of the vehicle can be controlled by adjusting the adjusting blades.

However, in the former approach relying on the variable screw-pitch rotor, the 20way to control the flight direction of the vehicle is to separately adjust the helix angle of each of the leaves. Thus, the adjustment is complicated and power loss tends to happen due to the variation of the helix angles. In the latter approach where the transverse shaft mounted with adjusting blades is utilized to control the flight direction of the vehicle, air eddy is prone to form around the adjusting blades 25and adversely affects the stability of the vehicle. Moreover, this approach requires complex adjustment and controlling device, thus increasing the size and weight, and reducing power efficiency of the vehicle.

i The aforementioned variable screw-pitch rotor also facilitates stabilizing the vehicle in flight. That is, when the vehicle loses its balance, the screw pitch of the rotor can be adjusted to rebalance the vehicle. However, the adjustment of the variable screw-pitch rotor needs complex mechanism, and has the problem of 5reduced power loss caused by the variation of the helix angles.

Furthermore, the fixing plates and adjusting blades adjusted by the controlling device of the controlling part serve to remain the vehicle stable and to control the vehicle to rotate left or right. The components provide the same function as the tail rotor of a normal helicopter. By offsetting the semi-torque generated by the rotation 10of the rotor, the downward wind generated by the rotation of the blades can make the vehicle to rotate clockwise or anticlockwise.

Conventionally, plural sets of fixing plates that are mounted under the leaves and plural sets of adjusting blades are further mounted under the fixing plates.
Thus, the adjusting and controlling devices have complicated structures. As a l5result, the size and weight of the vehicle are increased due to the adjusting device, thereby reducing power efficiency.

SUMMARY OF THE INVENTION

In view of the problems of the prior art, the objective of the present invention is 20to provide a bottom blade type vehicle that is simple in the structure and adjustment. The bottom blade type vehicle implements a fixed screw-pitch leaf having fixed helix angles and a fixed shape, rather than a variable screw-pitch rotor or a transverse shaft assembled with holding adjusting blades. The bottom blade type vehicle of the present invention thus can perform stopping, rotating left, 25rotating right, flying forward and flying backward by simply adjusting two adjusting blades.

The bottom blade type vehicle of the present invention is characterized in a fixed screw-pitch leaf horizontally mounted taking a center axis as the center; a power part mounted above the leaf; a controlling part mounted under the leaf;
a bridge plate vertically fixedly mounted under a round frame, wherein the a first and a second fixing plates and a first and a second protecting plates being crossed each 5other in a cross-shape taking the controlling part as the center, one end of the first and the second fixing plates and the first and the second protecting plates connected to the controlling part and the other end of them connected to the round frame; and a first and a second adjusting blades controlled by a controlling device of the controlling part, wherein the first and the second adjusting blades are mounted on l Othe first and the second protecting plates respectively.

As described above, the conventional bottom blade type vehicle uses the variable screw-pitch rotor that needs to be repeatedly adjusted on the helix angles or the long adjusting blades that are mounted in the transverse shaft for realizing the balance and stability of the vehicle during its forward or backward flight.

15Besides, for maintaining the vehicle balanced and stable, the installed variable screw-pitch rotor needs to be adjusted. The adjusting blades are installed and adjusted to offset the left or right rotation of the vehicle. However, the structure and the adjusting device are complicated and have the problem of reduced power efficiency. On contrary, in the present invention, the weight of the vehicle is evenly 20distributed so that the gravity of the vehicle is aligned with the center of the leaf.
Thereby, the present invention allows the vehicle to offset the semi-torque and to perform directional change, e.g. stopping, rotating left, rotating right, flying forward and flying backward by simply using the fixed screw-pitch leaf and the two adjusting blades.

25 Therefore, the bottom blade type vehicle of the present invention is simple in the structure and adjustment and is capable of achieving the optimum design of the fixed screw-pitch leaf of the vehicle, thus decreasing its size and weight in comparison with a variable screw-pitch blade type vehicle, and improving power efficiency, thus prolonging the flight duration of the bottom blade type vehicle.
BRIEF DESCRIPTION OF THE DRAWINGS

FIG. I is an oblique perspective view of a bottom blade type vehicle of the 5present invention;

FIG. 2 is another oblique perspective view of the bottom blade type vehicle wherein a part of components in FIG. 1 is removed;

FIG. 3 is a schematic drawing showing the weight distribution of the vehicle of FIG. 1;

FIG. 4 is a schematic drawing showing the vehicle inclined;

FIG. 5 is another oblique perspective view of the bottom blade type vehicle wherein a round frame and a bridge plate are removed;

FIG. 6 is a top view of FIG. 5 showing the blades posed to make the vehicle fly forward;

FIG. 7 is another top view of FIG. 5 showing the blades posed to make the vehicle fly backward; and FIG. 8 is a sectional view of the essential components of the bottom blade type vehicle of the present invention.
BRIEF DESCRIPTION OF THE REFERENCE NUMERALS OF MAJOR

1 center axis 2 leaf 3 power part 4 controlling part 5 round frame 7 controlling device 8 connecting wire 11 first fixing plate 12 second fixing plate 21 first protecting plate 22 second protecting plate 31 first adjusting blade 32 second adjusting blade 51 first bridge plate 52 second bridge plate 53 third bridge plate 54 fourth bridge plate 61 power source 62 power device 63 power gear 64 external gear DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Please refer to FIGS. 1 and 2 for the entire structure of a bottom blade type vehicle of the present invention that achieves the aforementioned objective.

In the present invention, a fixed screw-pitch leaf 2 is horizontally mounted Staking a center axis 1 as the center. A power part 3 is mounted above the leaf 2 while a controlling part 4 is mounted under the leaf. In addition, a first and a second fixing plates 11, 12 and a first and a second protecting plates 21, 22 are crossed each other in a cross-shape taking the controlling part as the center.
The cross-shape assembly is vertically connected inward to the controlling part and 10connected outward vertically to a round frame 5 and bridge plates 51, 52, 53, and 54. A first and a second adjusting blades 31, 32 controlled by a controlling device of the controlling part 4 are mounted on the first and the second protecting plates 21, 22, respectively.

As shown in FIG. 1, the round frame 5 of the present invention is a round-15shaped frame of the vehicle serving to transmit the wind generated by the rotation of the leaf 2 downward and to hold the fixing plates 11, 12, the protecting plates 21, 22, and the bridge plates 51, 52, 53, and 54.

Referring to FIG. 8, the center axis 1 is a circular hollow tube acting as a channel connecting the power part 3 and the controlling part 4 of the adjusting 20device of the vehicle. Shafts of the leaf 2 rotated anticlockwise by the power device are affixed to the exterior of the center axis 1.

The first and the second fixing plates 11, 12, as can be seen on the first fixing plate 11 in FIGS. 2 and 6, have their lower portions jutting out of the center axis 1 extending outward to form a ladder-like, forward bent body, so as to present an 25enlarged area for receiving wind as much as possible.

The first and the second protecting plates 21, 22 as well as the first and the second adjusting blades 31, 32 are shown clearly in FIGS. 2 and 5. The first and second adjusting blades 31, 32 are mounted on the first and the second protecting plates 21, 22, respectively. In addition, slots and hinges are implemented to attach the rectangular first and second adjusting blades 31, 32 to the first and second protecting plates 21, 22, respectively, so that the first and second adjusting blades 531, 32 can swing with respect to the first and second protecting plates 21, 22. The first and the second adjusting blades 31, 32 installed on the first and second protecting plates 21, 22 can be independently adjusted by the adjusting device.

The bridge plates 51, 52, 53, 54 protect the first and the second fixing plates 11, 12, the first and the second adjusting blades 31, 32, as well as the first and the l Osecond protecting plates 21, 22 during lifting and landing of the vehicle.
The bridge plates 51, 52, 53, 54 also ensure the wind coming downward from the leaf 2 can be well transmitted to the first and the second fixing plates 11, 12, the first and the second adjusting blades 31, 32, as well as the first and the second protecting plates 21, 22.

15 Furthermore, the first and the second fixing plates 11, 12 and the first and second protecting plates 21, 22 are such mounted on the controlling part 4, the round frame 5, and the bridge plates 51, 52, 53, 54 that they are firmly fixed to each other in a cross-shape. Thereby, the need of additional supporting base to support the vehicle can be eliminated.

20 FIG. 2 is another oblique perspective view modified from FIG. 1, wherein the round frame 5, the bridge plates, and the first protecting plate 21 are partially removed for illustrating the first protecting plate 21, the first adjusting blade 31, the controlling part 4 and the first fixing plate I 1 with enhanced clearness.

The present invention provides an approach to balancing and stabilizing an 25aircraft without using any variable screw-pitch rotor. The present invention implements the principle of balancing and stabilizing the vehicle by, taking the leaf 2 as shown in FIG. I as the vertical center, evenly distributing the weight of the vehicle to portions above and below the fixed screw-pitch leaf. The fixed screw-pitch leaf 2, as a rotator, is innately capable of maintaining level and balanced during rotation. The present invention substantially employs the capability of maintaining level and balanced as the resources of balancing and stabilizing the 5vehicle.

Meantime, the capability of the fixed screw-pitch leaf 2 for maintaining its levelness and balance is referred to as the "righting force" in the present invention.
FIG. 3 is a schematic drawing of the vehicle showing the weight evenly distributed to the upper portion and the lower portion located above and below the 10fixed screw-pitch leaf 2, respectively. FIG. 4 shows the flying vehicle of FIG. 3 inclined because of an external factor such as uneven weight distribution during flight or irregular airflow acting on the fixed screw-pitch leaf 2 and the vehicle swings in the horizontal direction of the fixed screw-pitch leaf 2 under the righting force "f'.

15 As shown in FIGS. 3 and 4, there are the force "e" causing the vehicle to swing and the righting force "f' facilitating the vehicle to maintain horizontally level during the rotation of the fixed screw-pitch leaf as the rotor. If the righting force "1' surpasses the swinging force "e", the vehicle maintains horizontally balanced and stabilized.

20 On the contrary, when the righting force "f' is smaller than the swinging force "e", the vehicle remains swinging. In addition, the swinging force "e" is associated with the weight of the vehicle. The heavier the vehicle is, the stronger the swinging force "e" is. Therefore, reducing the weight of the vehicle helps the righting force "f' to maintain the vehicle horizontally balanced and stabilized. In other words, 25reducing the weight of the vehicle facilitates maintaining the vehicle balanced and stabile during flight.

However, since the vehicle needs at least a power source, the power part and the controlling device to operate, the approach of reducing the weight of the vehicle has its limitation.

For addressing this problem, as shown in FIG. 3, the vehicle is such configured that the overall weight of the entire vehicle is distributed to the upper Sand the lower portions that take the fixed screw-pitch leaf as the center 2.
Thereby, the balance and the stability of the vehicle can be realized with a relatively small righting force as long as the swinging force equal to the weight difference between the upper portion and the lower portion of the vehicle can be offset. Thus, the swinging force can be minimized by reducing the weight difference between the I Oupper portion and the lower portion.

Herein, the gravity center is at the intersect between the center axis 1 and the fixed screw-pitch leaf 2, as the point C or G in FIG. 3.

Therefore, if the weight of the vehicle is evenly distributed to the upper portion and the lower portion so as to make the gravity of the vehicle aligned with 15the horizontal center of the screw-pitch leaf 2, the stability of the vehicle can be achieved with a relatively small righting force, thereby reducing power loss.

As described above, when the total weight of the vehicle is evenly distributed to the upper portion and the lower portion located above and below the screw-pitch leaf 2, only a small righting force is enough to maintain the vehicle balanced and 20stable during flight, and in turn the fixed screw-pitch leaf is competent to replace the variable screw-pitch rotor that is used in the prior art and is complex in the structure and adjustment.

Besides, without using the variable screw-pitch rotor that is used in balancing and stabilizing device in the existing bottom blade type vehicle, the present 25invention minimizes the power loss caused by the variable screw pitches by implementing the fixed screw-pitch rotor, so as to simplify structure and adjustment of the disclosed vehicle. By using the simple fixed screw-pitch leaf to replace the variable screw-pitch leaf, it is achievable to realize the optimum design of the fixed screw-pitch leaf of the vehicle, thus simplifying the vehicle in the structure.

FIG. 5 is provided for illustrating the operation of the vehicle, including stopping, left rotation, right rotation, flying forward and flying backward.
As 5compared with FIG. 1, the round frame 5 and the bridge plates 51, 52, 53, 54 are removed to show the locations and installation of the first and the second adjusting blades 31, 32 so as to clearly provide the structure of the first and the second fixing plates 11, 12 as well as the first and the second adjusting blades 31, 32. In the drawing, the first and the second fixing plates 11, 12, as well as the first and the 1Osecond protecting plates 21, 22 where the first and the second adjusting blades 31, 32 are attached, are fixed in a cross-shape to the controlling part 4.

First, please refer to FIG. 5 for the stopping and left and right rotation of the vehicle. When the fixed screw-pitch leaf 2 is powered to rotate anticlockwise and flies the vehicle, the vehicle rotates clockwise according to the semi-torque 15generated by the rotation of the leaf.

At this time, for offsetting the semi-torque generated by the rotation of the leaf 2 and preventing the vehicle from rotating in either direction, what is needed to do is to pose the first adjusting blade 31 "s" and pose the second adjusting blade 32 at "y". At this time, the downward wind generated by the rotation of the leaf 2 acts 20on the first adjusting blade 31 and the second adjusting blade 32, thereby offsetting the semi-torque of the vehicle and restricting the vehicle from rotating.
Thus, the vehicle is stabilized and stops.

Similarly, when the first adjusting blade 31 is posed at "t" and the second adjusting blade 32 is posed at "z", the expanding angles of the blades are enlarged.
25Thus, the downward wind generated by the rotation of the leaf 2 acts on the first adjusting blade 31 and the second adjusting blade 32, thereby generating a force greater than the semi-torque of the vehicle so as to make the vehicle rotate anticlockwise and then complete its left rotation.

On the contrary, when the first adjusting blade 31 is posed at "r" and the second adjusting blade 32 is posed at "x", the expanding angles of the blades are reduced.
Thus, the downward wind generated by the rotation of the leaf 2 acts on the first 5adjusting blade 31 and the second adjusting blade 32, thereby generating a force smaller than the semi-torque of the vehicle so as to make the vehicle rotate clockwise and then complete its right rotation.

Please refer to FIGS. 5, 6, and 7 for the forward and backward flight of the vehicle. The vehicle can be set to fly forward or backward by changing the angles 10of the first adjusting blade 31 and the second adjusting blade 32. For example, if it is desired to move the vehicle toward the first protecting plate 21, what is needed to do is to set the first adjusting blade 31 at "t" and set the second adjusting blade 32 at "x". By merely adjusting the angles of the adjusting blades to make the wind only acts on the first adjusting blade 31, the vehicle is set to fly forward.

15 FIG. 6 is a top view of the blades. Please see the adjusting blades 31, 32 in the drawing for learning the principle whereupon the vehicle flies forward.
Therein, the first adjusting blade 31 is expanded to take a relatively large horizontal area while the second adjusting blade 32 is retracted to leave the horizontal area therearound vacant.

20 Therefore, since the first adjusting blade 31 resists the semi torque more than the second adjusting blade 32 does, the vehicle inclines toward the first adjusting blade 31. Besides, the leaf 2 corresponding to the second adjusting blade 32 receives less resistance induced by the wind and tilts upward due to the relatively large lifting force while the first adjusting blade 31 inclines downward due to the 25relatively small lifting force, so that the vehicle flies toward the first protecting plate 21, as indicated by the downward arrow in FIG. 6.

Moreover, if it desired to fly the vehicle toward the second protecting plate 22, under the same principle, the first adjusting blade 31 is placed at "r" and the second adjusting blade 32 is placed at "z". By merely adjusting the angles of the adjusting blades to make the wind only act on the second adjusting blade 32, the vehicle is set to fly backward.

That is, as shown in the top view of the adjusting blades in FIG. 7, the second adjusting blade 32 is expanded to take a relatively large area therearound while the firs adjusting blade 31 is retracted to leave the area therearound vacant.

Therefore, since the second adjusting blade 32 resists the semi torque more than the first adjusting blade 31 does, the vehicle inclines toward the second adjusting 10blade 32. Besides, the first adjusting blade 31 receives less resistance induced by the wind of the leaf 2 and tilts upward due to the relatively large lifting force while the second adjusting blade 32 inclines downward due to the relatively small lifting force. As a result, the vehicle backs toward the second protecting plate 22, namely along the upward arrow in FIG. 7.

As described above, the stopping, progressing, backing, left rotating and right rotating can be achieved by independently adjusting the first adjusting blade 31 and the second adjusting blade 32, causing the vehicle simple in structure.

Referring to the above embodiment and FIG. 8, taking the fixed screw-pitch leaf as the center for mounting a power source 61 on the power part 3, the power 20source 61 is allowed to transmit power downward by means of a connecting wire 8 passing through the tubular center axis. The rest parts of the vehicle, namely an external gear 64, a power device 62, a power gear 63, a controlling device 7, the first and the second fixing plates 11, 12, the first and the second adjusting blades 31, 32, the first and the second protecting plates 21, 22, and the bridge plates 51, 2552, 53, 54 can then assembled below. Thereby, the total weight of the vehicle is distributed evenly above and below the fixed screw-pitch leaf 2. Herein, the power part 3 and the controlling part 4 are installed according to weight balance and design so as to have the gravity of the vehicle aligned with the fixed screw-pitch leaf 2 and the center axis 1.

The operational principle of the present invention is as shown in FIG. 8. The connecting wire 8 connected to the power source transmits power to the controlling 5device for controlling the power device. When the power gear 63 fixed center axis to the shaft of the power device rotates, the external gear 64 engaged with the power gear 63 from outside rotates at the same time, thus making the fixed screw-pitch leaf 2 rotate and in turn flying the bottom blade type vehicle.

Claims (4)

1. A bottom blade type vehicle, comprising:

a fixed screw-pitch leaf horizontally mounted taking a center axis as the center;
a power part mounted above the leaf;

a controlling part mounted under the leaf;

a first and a second fixing plates and a first and a second protecting plates being crossed each other in a cross-shape taking the controlling part as a center, each of the first and the second fixing plates and the first and the second protecting plates having one end connected to the controlling part and an opposite end connected to a round frame;

bridge plates vertically fixedly mounted under the round frame; and a first and a second adjusting blades controlled by a controlling device of the controlling part;

wherein the first and the second adjusting blades are mounted on the first and the second protecting plates respectively.
2. The bottom blade type vehicle of Claim 1, wherein the vehicle has a weight of an upper portion equal to a weight of a lower portion, wherein the upper and the lower portions take the leaf in a horizontal position as a center, and wherein the vehicle has a gravity located at an intersect between a horizontal of the center axis and a vertical of the center axis.
3. The bottom blade type vehicle of Claim 1, wherein the vehicle is set to offset semi torque, or to perform stop, forward, backward progress, left rotation or right rotation by adjusting the fixed screw-pitch leaf and the first and the second adjusting blades.
4. The bottom blade type vehicle of Claim 1, wherein each of the first and the second fixing plates has a lower portion jutting out of the center axis expanding outward to form a ladder-like, forward bent body.
CA2677126A 2009-09-22 2009-09-22 Bottom blade type vehicle Abandoned CA2677126A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CA2677126A CA2677126A1 (en) 2009-09-22 2009-09-22 Bottom blade type vehicle

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CA2677126A CA2677126A1 (en) 2009-09-22 2009-09-22 Bottom blade type vehicle

Publications (1)

Publication Number Publication Date
CA2677126A1 true CA2677126A1 (en) 2011-03-22

Family

ID=43781858

Family Applications (1)

Application Number Title Priority Date Filing Date
CA2677126A Abandoned CA2677126A1 (en) 2009-09-22 2009-09-22 Bottom blade type vehicle

Country Status (1)

Country Link
CA (1) CA2677126A1 (en)

Similar Documents

Publication Publication Date Title
JP5549019B2 (en) Mitsuha Lower Wing Aircraft
EP2340880B1 (en) Dual-rotor model helicopter control system
KR101217804B1 (en) Bottom propeller control type vehicle
CA2956117C (en) A propeller assembly with at least two propeller blades
AU2004240870B2 (en) Rotor and aircraft passively stable in hover
US8186615B2 (en) Rotor head of remotely-controlled helicopter and remotely-controlled helicopter
US20110024553A1 (en) Bottom Blade Type Vehicle
WO2017175410A1 (en) Helicopter rotor head, multirotor helicopter, and helicopter
CN108602559A (en) Hybrid more rotors and Fixed Wing AirVehicle
KR100901755B1 (en) An apparatus for steering a tailwing of remote-controlled bird mobile with weight-reduced tailwing
US5381988A (en) Tethered model gyroglider
CN101417182A (en) Toy helicopter having a stabilizing bumper
US7134840B2 (en) Rotor system for a remotely controlled aircraft
CA2677126A1 (en) Bottom blade type vehicle
JP2012180050A (en) Flapping flight device
KR20080058188A (en) Bottom blade type vehicle
EP2279944A1 (en) Flying platform with a lift rotor
CA2958632A1 (en) Toy helicopter and balancing device therefor
JP4702882B2 (en) Small rotorcraft
JP3154400U (en) Bottom winged vehicle
EP2969750B1 (en) Automatic pitch change rotary wing rotor system and method of rotor control
KR20100094056A (en) Two propeller type vertical take-off and landing vehicle
CN112693605A (en) Flapping wing aircraft
WO2020125523A1 (en) Foldable multi-rotor unmanned aerial vehicle
JP3111012U (en) Structure of the main rotor of helicopter type rotor blade

Legal Events

Date Code Title Description
EEER Examination request
FZDE Discontinued